Digital Racing

Arduino Nitrox Analyzer phase 2: ADC/I2C

2011-10-26T18:04:00.000-07:00

I was able to get reliable samples on the Arduino in the original post. I did it by amplifying the input voltage source by 43x which put it into a reliable range for the built-in ADC (analog to digital converter) of the Arduino. This is probably good enough. But things could be better- I could reduce the sampling voltage of the Arduino so that it compares to a smaller value instead of 5v. The problem with that is that pretty much limits anything else I'd want to sample to the same voltage range. I just got a bunch of sensors that are up to 5V- so I need those to be read over the 5V range.

John H helped me a lot in figuring this out- as he went through the same exercise I did before he came to this conclusion

The solution is to use an external ADC. Two big benefits to this:

I can use different voltages for each one
The resolution is much higher.

The second part is where it's really going to matter for me, because I have a long-term plan to use the Arduino to take care of several functions, and being able to read multiple sources- and accurately is the issue. The Arduino is 10-bit, which comes out to 1024 discrete values. At 5V, that's 5mv per step, which is far too large for something like a pressure transducer which goes to 10k psi.

Enter the ADS1115. It's a TI ADC with a ton of features including a comparator. This is an additional feature that let's me program a threshold where I could set an alarm- such as an overpressure switch. I should be monitoring the pressure via the Arduino itself, but this could be a hardwired backup to that. It also has 4 single-ended inputs, or two differential inputs.

I found a guy on Ebay selling this *tiny* (about half the size of a grain of rice) chip mounted on a nice PCB for $15. It's a well-done chip, but light on documentation.

The hard part about the ADS115 is how to wire it up! I was able to get this diagram off of the listing on Ebay. But, then I have to get it talking to the Arduino.

The Arduino uses I2C which is a serial protocol. There's only one set of pins on the Arduino that you can hook up I2C. But.. I2C is an addressable protocol, so you can have 127 devices on that set of pins. I'm hoping the 1115 can serve all my ADC needs, but I could get a second one easily.

This page was a good start- it talks about I2C and helped me get the next set of pins figured out. SDA and SCL are Serial Data and Serial Clock, respectively and map to pins 4 and 5 on the Arduino. GND and VCC were easy enough to get as well.

RetroLefty published a very nice test sketch which, by reading through the comments, allowed me to get it talking using differential inputs on Analog 0/1. And it worked! Even with the 'worst' resolution, each count is 0.18mV. Cranking up the resolution let me get accuracy to 0.02mV. And that's not even as high as it goes!

This solution is sounding a lot better than my amplified one. But, there may be a reason to use the op-amp yet. If I have enough inputs, I may need to use the single-ended counters (4 of them) instead of the pair of differential. And, this circuit lets me turn a differential into a SE if it doesn't work on its own. My initial attempt and single-ended without the circuit failed, but I'll revisit it.

It took a while, but slogging through the datasheet (btw, datasheets are your friend when dealing with ICs), I found that you can change the address of the ADS1115. It is normally 0x48, but by connecting one pin to either VCC, SDA or SCL, you can bump to 3 higher addresses (in that order).

(18 November 2011)

Last night was a success. I was able to run my compressor with the analyzer in the intake with some degree of confidence in the results. But the road getting here was complicated.

The test sketch I used above was solid- but subsequently a library was created to do I2C communication in a standardized way. I wanted to go down this route because there are other I2C devices I may want to add and I didn't want to write customer communication code for each of them. I already knew I might need more than one ADS1115, and unless I wanted all my pins on the Arduino taken up, I probably need an I2C LCD display. Fortunately, I2CDevLib was created. It builds on the Wire library for Arduino and simplifies some of the communication protocols by having a bunch of read and writebit functions because that's how you communicate in I2C. For the ADS1115, for example, you set a bit that you're going to do a read, and you can set the gain, the inputs, etc.

Except it wouldn't work for me. Only the simplest examples would work, and I was trying to use the ADS1115 as designed- I wanted several inputs and read between them. I would set the mux to read from input 0/1, and then I want to read something else (pressure) from 2/3. I would get bizarre values. I also tried to set the gain and it wouldn't take effect- and would then read a different input! It took a full weekend of debugging, but I finally found the problem. When you need to write to a 16-bit register, you have to write the entire register- you can't simply 'write this bit' because a byte (8 bits) is the smallest addressable space. So, what you have to do is read the existing 16-bits and update just those bits. This is done by using a 'bitmask'. You create a bunch of zeros/ones to 'mask' the values you want to reset. If you have 16x1s, and then do an 'and' function on the original, you'll end up with the original again because a '1' and a '1' gives a 1, but a 1 & 0 gives a zero. So what you do is build a mask with zeros in the spaces you want to wipe out. You then put in your values where they should like up and OR them together so that only new '1's you added get added to the register before you write it back. Here's the way it is supposed to work (setting a '010').

     //    xxx   args: bitStart=4, length=3
    // 11100011 mask byte

     // 10101111 original value (sample)

     // 10100011 original & mask// 10101011 masked | value

What happened instead was that the mask was set too large and was wiping out other values it shouldn't have. I contacted the author and he made changes to the base code.

What was missing in the base ADS1115 code was functions to read the differential inputs- it only had code to read the single-sided ones. I went ahead and wrote code for those and submitted them to the open-source project. And when I found that what I really wanted were voltage values for the different inputs, I wrote code for that was well.

What I ended up with was very simple code to get one input, change the gain, then get the other input. This way, I could read the oxygen sensor to a very high accuracy, and also get the pressure which had a much wider range of values, meaning I had to turn down the gain on it.

I did a successful run last evening reading my oxygen sensor while I pumped Nitrox. Oddly, though I was reading to a high accuracy, I also got pretty substantial variances in my reading. This had be worried because one of the concerns of building a nitrox stick to blend oxygen and air is to make sure that it is well mixed, otherwise, you could not know what you're really pumping. So I was thinking that my stick was defective. While I was pumping, the oxygen ran out- and yet the varied reading still continued. I think this might be because I'm reading the ADS1115 at a very high rate (800 samples per second), as well as 'single shot' mode. I should probably switch to continuous mode, and perhaps even do averaging to get consistent numbers if needed.

     

Compressor Monitor

2011-10-23T20:43:00.000-07:00

A java app I plan on writing is going to allow monitoring of a compressor from a BT-enabled java application. I may do the first version in Android for myself, but I'll probably have a desktop version as well.

Feature	Notes	Done
Monitor pressure		Table Cell
Time remaining until set pressure	Table Cell	Table Cell
Alarm for pressure level	Table Cell	Table Cell

Ideal Mix, an Android Mixer application

2011-10-23T20:40:00.000-07:00

I've written a small android application to help the mixer do various tasks. I'll eventually put it up for sale, but for now, I'm using it to do a couple of things that I need. I'll keep a list of the features I'm planning on adding and an update when I've done them.

I like doing things agile-based, so I'll keep a feature backlog.

Feature	Notes	Complete
Ideal Mix	Calculate the best mix for a particular depth	8/1/2011
Calculate O2 in air	This gets the humidity and temperature to find the free O2. Used for when you calibrate in air.	10/29/2011
	Table Cell	Table Cell

Arduino-based Nitrox analyzer

2011-09-24T23:18:00.000-07:00

In an earlier post, I described the common method of making a nitrox analyzer out of a typical digital voltmeter and an oxygen sensor. It works well, lots of people have made them.

But I just picked up a nice programmable microcontroller. It's called Arduino- and is cheap. Here's my plan for using it as a nitrox analyzer.

Be able to adjust to any type of oxygen sensor
Compensate for relative humidity (when you want to use it an an input to a nitrox stick)
Calibrate meter on 100% O2 and/or 20.9% (air)
Auto shutoff
Battery Meter

It was roughly possible to do this with a pure hardware-based system. You put a potentiometer on the reading circuit to change the voltage divider and you can adjust. Relative humidity, you had to fake it out by reading the RH and then adjusting down

For me, I'm going to try to have it all built-in. First thing is first- we need to read the value coming out of an oxygen sensor. I'm going to use the common sensor we see, which is a Teledyne R-17. In 100% O2, it reads 62mV, and in 20.9% (air) it reads around 10mV.

First thing's first- get a sensor, get an Arduino.

I got my Arduino for $25 at TechShopRDU which is a local hobbyist center. It is an amazing place, and it was great to pick up one of these off the shelf.

Looking at the Arduino, it can read analog voltage of 0-5V in 1024 increments, or 5mV per increment. Not enough detail! But.. you can reset that voltage. By setting the input range to 1.1, you get 1024 increments or each value is about 1mv.

This is done by:

void setup() {
Serial.begin(9600);

// Set the reference voltage to be 1.1V to get more resolution
analogReference(INTERNAL);
}

Except.. it didn't work. It should have reduced the range and increased the resolution. I tested my sensor in air and got 11mV. But when I let the arduino read it, I only get 7mV. That's pretty far off. One thing I'm considering is using an opamp to up the gain on the sensor. Something like this:

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1272911672/all

I don't know anything about op amps. But I found one on my desk. Weird, eh? It was leftover from when a local RadioShack was closing- I bought a lot of stuff, and this was like in the 10c bin. I need to see if it is applicable to my circuit.

One biggie that is going to interfere with my design is that op amps seem to require positive and negative voltage. Some designs just use a couple of 9v batteries, one flipped to give negative voltage. This page gives a history (the designer of the modern op amp retired at age 30) and sample designs, as well as a dual 12v power supply.

But I don't want dual power supplies. In the Ti link above, you can fake a negative power supply by using a single power supply and creating a virtual ground with a voltage divider.

Finally, after seeing that an LM324 is a commonly available quad op-amp (Radio Shack, $3), I found a project that used one... and it hooked up to an Arduino. Perfect. http://www.practicalarduino.com/projects/water-tank-depth-sensor

Off to RadioShack to get the the LM324, then time for some breadboarding.

(several days of design and breadboading)

This morning, I cam up with this circuit:

Stef says "that's the best circuit I've ever seen". I was quite proud! So tonight, I wired it up. I calculated the gain needed to be about 40x, so that my Rg (variable resistor) should be 800ohms or so. The LM324 is actually four op-amps in a single IC. You can wire it up a bunch of different ways, but I chose an instrumentation amplifier as it was close to the Practical Arduino book above. But it didn't work. I got 3.62v as the output when compared to ground. Which should have been nicely in range. However, the signal didn't vary as I blew on the sensor. I went and tested the voltage at pins 1 and 7 and got nice variance (about 300mv) between them, but for some reason actually amplifying that difference got me nothing. It could be that the feedback circuits were overcompensating and driving the difference down, or it could be simply that I was using cheapo 5% resistance capacitors and it was making my readings meaningless. Using a simple amp (one of the 4 op amps) could work, I'd get a lot of variance, but I'm bummed that my fancy circuit failed. So, I did research and found that they have ICs that have the three op-amps in them already with 0.1% resistors built-in. They're more expensive than the LM324 I paid a couple of bucks for, but they'd be far less than having to source fancy resistors. And even better, I found the AD623 off Ebay for $3 shipped. I chose the AD623 because it is a single-supply amplifier (like the LM324) and the only piece I need to do a 40x amplification is a 2.5kOhm precision resistor (and I can probably skip a high precision resistor as I'm going to have the arduino do the tare-ing of steady-state)

The AD623 experiment was a failure- I did not get the result I planned. I got a high voltage without even any input.

And then, last night I figured out what I was doing wrong. Let me help those of you who are playing with an IC. The pins are numbered starting next to the 'dot' as pin 1. This is on the side with the divot. And then, the numbers are COUNTERCLOCKWISE around the chip. Notice the ALLCAPS. They are not numbered top-to-bottom, left to right. On an 8-pin chip, pin 5 is across pin 4, not pin 1 (that would be pin 8). I feel pretty stupid.

I made a simple differential op-amp using a single amp from the LM324, but really any single-sided op-amp would work.

It only needs four resistors and I got a nice linear increase in my sensor. To make it really simple, just use Rg=Rf and R1=R2, and the gain becomes Rf/R1. The reason I went with a differential sensor is that my sensor isn't a voltage to ground, but rather a voltage difference.    I'm using 44k for my Rf and 1k for my R1 values which gives it 44x and my measured difference was 43.7. Close enough!

Since I learned to count again, I also rewired my single-supply instrumentation amp (AD623AN). And I got strange results. It only requires a single resistor, which at 2000Ohms would give it a 50x gain. But instead, it got a 27x gain. And it wasn't linear- at higher inputs, the gain went up to almost 40x. Something was very strange. And I used two different 623s and got the same results. I even built a voltage divider and tried to add in a reference voltage. Somewhere buried in the datasheet is probably the reason, and it has something to do with how much gain it can give close to the 'rails' (p.20). But it seems the issue only occurs <10mV of the bottom rail (which extends below zero) to 4.9V on the top end. But since it is really three op-amps in a single package, there's a table of min/max values. The max gain could be as low as 18x, and for my situation might top out at 49x. Hmmm. I may play with it some more, because the 623 sounds like the perfect chip!

The AD623 is a bizarre chip. I could not get it to amplify linearly.   The trick I tried was to force one of my sensor sides to ground (through a 10k resistor) so it didn't float. I got solid reliable readings on the sensor side. And at the low end of the scale, I got my expected 50x gain. However, when I upped the values coming from the sensor to 53mV, I only got a 29x gain on the high end. There was a blurb in the datasheet about a max gain in the 40s in certain situations, so I changed the gain to 35 by going to a 3k resister- and at the low end I got the expected gain, but at the high end, it went down into the 20s. I gave up.

I went back to the LM324, using only a single op amp as a differential amp.

Here's my final circuit:

I still have three op-amps available for use for something else if needed. And here it is on the breadboard:

Once I get my other components I'll move the design to a veloboard to make it somewhat permanent. I've ordered a temperature/humidity sensor and now I'm back to doing some coding for Android (in Java) while I wait on some components to arrive.

I just got a new sensor- a Teledyne R-17 clone and I wired it into my circuit. It reads 13.8mV in air, and I up it 44x to get it into a range usable by the analog read of the Arduino. I wrote Arduino code to wait for the user to sample air (assumed to be 20.93) and then press a button. I take 10 quick readings, then average the result.   This sample voltage becomes my calibration using math- no resistors needed!

After the calibration is set, the user can press the button again to get a reading (I do the 10x average again). I do a simple (readingV/calibrationV * 20.93) to get the percentage of O2.

Press button when sensor is in air
sensor value = 109.00:V = 532.23
Calibrated voltage is: 532.23
sensor value = 109.00:V = 532.23
Oxygen percentage:20.93
sensor value = 109.00:V = 532.23
Oxygen percentage:20.93
sensor value = 110.00:V = 537.11
Oxygen percentage:21.12
sensor value = 115.00:V = 561.52
Oxygen percentage:22.08
sensor value = 202.00:V = 986.33
Oxygen percentage:38.79
sensor value = 501.00:V = 2446.29
Oxygen percentage:96.20

I notice that my value at near 100% is only half the available range (1024), so I can choose a lower voltage (or higher amplification) to get greater resolution.

Cost of the project:

Arduino: $25
Veloboard: $3
Resistors: $2 (Radio Shack)
LM324:$3 (Radio Shack)
Sensor: $65

After speaking with another hobbyist about how he did his micro-controller sensor, he said you really need an ADC to do it right. The built-in analog-to-digital controller on the Arduino is simply too coarse to get good readings. I've ordered an ADS1115 for $15 to add to my Arduino to see if I can get better readings.

The next step is to hook up a display and give it an independent power supply (9v battery).

The new Nitrox Stick

2011-07-25T18:04:00.000-07:00

I sold my 2nd Nitrox stick when I sold my 8CFM Mako compressor, so it is time to create a new one.

(put in lessons learned from other sticks)

Here's a link to the actual filters used in the commercial stick: http://www.maradyne.com/marion/sumpfilters/dual_sump_filter.html

To get extra diffusion, the oxygen is injected into the top of the inner filter and passes into the outer, while ambient air goes from the outside the outer and joins with the drawn air of the inner. I'm not convinced this is the right design- I guess oxygen is forced into the stream in the space between the inner and outer and is unlikely to exit the unit. But my previous one simply had the oxygen below the filter intake and accomplished the same thing. Some thoughts I have right now are I wonder if a fine nozzle (think fuel injector) could help pre-diffuse the oxygen? Then again, having it pass through a filter element would distribute it well and not have a point source.

Here's a diagram of the dual-element filter. I've been trying to find one and it seems like a specialty part. I won't find it on the shelf of any auto-parts store. Looking at that link, I came up with 'SU-65-SF-32', which is a dual-element, 50GPM filter (no magnet), with a 2" port. It has 450 in^2 of surface area which sounds pretty darn large. I found one here for $70. Why 50 GPM? Well, each cubic foot is actually 7GPM of fluid!
Heck, 50GPM is only good enough for a 7CFM compressor. Upon which I throw out the 'bullshit' flag. The existing filter for the compressor is 3"x5" cylinder. That's only 60 square inches of filtration. Looking at my diesel suburban (6.5L engine), the filter is about 14"x6".

That's 320 square inches of surface area. Maybe the SU filter is including the inner filtration area, which means it is still going to be bigger than the Suburban. And let's see what 6.5L of displacement does at 1k RPM.... My calculation shows it as 1700GPM. Now, granted, I'm not breathing through my air intake, but I'm also not filtering it in my compressor either. Between the suburban air filter and the little one on the intake of the compressor should be fine.

Now the question to myself is: I see an advantage to a dual-filter design for the diffusion of oxygen. But why not just put one filter inside of another? I'm going to see if a big ole filter from say my Suburban and a smaller filter made to fit inside it would work.

Wiring the Bauer

2011-06-23T20:51:00.000-07:00

Jim suggested before I do anything that I understand the existing circuitry- I drew a very crude sketch and then put it into an e-CAD program. Which was actually an adventure- simple diagram drawing is hard to find. Everything is either digital circuitry (and most allow you to go right to a PCB) or not electrical in nature. I ended up with TinyCAD. I was happy with it see what you think?

I had a big white box at the top of the control box that I couldn't figure out- turns out it was a timer. I guess I should have known when it said on it "15 minutes, 6 seconds"

Now, this is a typical electromechanical way to control the compressor. Newer ones are computer controller, and I may go that route, because I want to learn to program an Arduino.

But before I think of that, I need to figure what all these 4 bundles of wires do. I'm guessing some of it is power. Then there is an overpressure switch. And an oil pressure switch. On the panel there's an oil pressure override. Maybe one is for the hour meter? Time to start tracing wires.

(in progress)

Panel revision

2011-03-30T21:38:00.000-07:00

I've tweaked the design yet again; if I use 4-way connectors, I can get rid of half the 3-ways, plus the connections between the. Of course, the 4-ways need to be less than twice the price of 3s. Not always the case.

The big question is to use tubing for the 'manifold' or to use NPT. If I use nipples to connect the manifold pieces, they'll be quite tight.

Ode to Denton

2011-03-29T20:13:00.000-07:00

I don't know Denton. But like a lot of other divers-with-compressors, we've used his website as a resource and inspiration for our own setups. He took a LOT of time writing up detailed instructions on how he set up his impressive mixing system.

It seems he announced the website in June of 2006, and later that month I start to see mentions of his funeral. I'm not sure of the details what happened, but the information is out there. I find a lot of similarities between he and I and it is interesting- and not surprising. He would have been 41 years old this year, was a computer engineer and loved to dive and travel. And he died while diving, apparently after a great dive, and apparently for no reason other than it was his time.

So, not only do I feel a kinship with him as a technical person doing technical diving, but I've got another reminder of him- some of my bank bottles and hardware came from his setup. From what was posted about him, I'm honored to be using some of his equipment in the way that he meant for it to be used.

Good Journey, Denton

Designing the mixing panel

2011-03-21T20:03:00.000-07:00

It's a curse to be an engineer. I've spent days and days trying to design a mixing panel for my compressor. First I had to figure out how to set up my bank bottles. I've sketched it all.

My goal was to be able to run the compressor and either fill a bank or fill a bottle. Furthermore, I wanted to be able to run the compressor and fill a bank... while filling bottles off a different bank. That is what made it interesting.

Initially, I had come up with doing it using 3-way valves. It made perfect sense- each bank could either be turned to the bottles or turned to the compressor (manifold). I could fill two banks at once, and still fill bottles off the third bank. Here's a sketch of that:

But then reality set in. I can buy needle valves for $12 up to $40 for nice panel-mount ones. The absolute cheapest ball valve I found was $90. And $170 for a 3-way panel-mount. Ouch. And then, every subject expert I spoke with said the same thing: ball valves aren't what you want. Besides the up-front cost, they leak, they are expensive to rebuild, and they 'shock' the system when flipping from one side to another.

So we're going to use line valves. I took a look at Gypsy Divers' setup and liked their big panel. It made sense walking right up to it. With that in mind, I came up with this. Unlike the 3-ways, any gas changing requires two knobs to be twisted, but needle valves also let you do flow control.

At this point, I need to decide on how all these are going to be plumbed. Flex hose is easy- but it isn't cheap. Steel tubing seems to be a popular design, so I'm going to look into it further.

Figuring out circuits for a Nitrox Analyzer

2009-09-14T13:55:00.000-07:00

I'm quite interested in building my own nitrox analyzer. I can always purchase one- and in fact, I own one- and have a second one in pieces.

The reason I'm interested is that I'd like to do more than just have an analyzer- I'd like to understand it- and modify it to suit some of my needs. For example, if the battery powering the analyzer starts to go bad, then the analyzer will read incorrectly, so you might not know it. Or what about if you decide to use a different sensor? You'd have to get new analyzer circuitry, as the output of an oxygen analyzer (the little fuel cell) varies from manufacturer to manufacturer.

Fortunately, the overall concept is fairly easy- an oxygen sensor gives a tiny voltage when exposed to oxygen molecules. Just having a sensor and a voltmeter means you've got a rudimentary analyzer.

I can expose the sensor to air, take a reading, then expose it to a nitrox mix, take that reading, get the ratio between the readings, then multiply it by my start percentage of O2 (20.9). Sensors- fortunately- are linear, so this works. If my voltage reading is 10mV when I read air, and 20 when I read my nitrox mix, then my percentage of oxygen is (20/10)*20.9 = 41.8% O2.

But who wants to whip out the calculator every time- oh- the cost of those nitrox analyzers. Well, what if you could use the guts of a multimeter to do the calculation for you?

That's what most of these home-grown analyzers are. You can find plans for building your own in the book The Oxygen Hacker's Companion. I've also found some plans on the net- the ones I've been studying a lot because they go into detail about what to do, rather than just 'solder this wire'- is here. The heart of any multimeter is the ability to take an analog signal (usually milliVolts) and turn it into a display of decimal digits. Each panel is probably different, but it looks like all of them use a standard IC called an ICL7106. It can take a signal up to 200mV and display it on its display. It uses a voltage divider (fancy way to say resistors powered with a higher voltage) to create a reference voltage and has circuitry to convert that into the digits.

Here's the circuit of this reference voltage. It is important, because this is what we actually need to modify to reset it to our needs for our particular fuel cell. That being- we could just read the millivolts- but that doesn't help us- we want it to read in percentage of oxygen.

A voltage divider is a way to precisely take a stock voltage- 3V in this example, and output a lower voltage.

The way a voltage divider works is by simply following Kirchhoff's Law. The law states that all voltages in a closed loop must sum up to zero. So in our circuit above, we start off with a 3V on the 'right' that must have -3V of voltage drops on the 'left'. There are a couple of ways to figure out how this works- we know that V=IR. V3=IR2+ IR3 + IR4. Since the resistance values are known, I can solve for I and get each voltage drop. But, I don't need to know I at all. I know the voltage is going to drop proportionally according to the resistor associated with it. A big resistor means a big drop. Voltage at 36 is going to be proportional to the maximum of 3V. In other words, it's going to be a ratio of the drop at the big resistor compared to all the resistors.

V36=V* (R2 / (R2 + R3 + R4))

Putting in values (assuming the center for the variable resistor), we get V36 = 3000mV * (30k)/(30k + 909 + 100). V36=3000 * (30,000)/(31009). This ratio gives us 2902.38mV. That big resistor eats up a bunch- so what's the value going to be? Just subtract the start voltage, which turns out to be ~100mV. This is meant to 'center' the reading on the scale. If you notice, the variable resistor allows us to tune the reading slightly from 0-200 on the denominator so that if some of the resistor values aren't spot-on, we can factory calibrate the meter to read properly with a known 100mV source.

The circuit uses this as a 'reference' when deciding what the input voltage is. So, in the example circuit above, the voltage at (36) is 100mV. Which would be great for us if our oxygen sensors used this range and it matched up to percentage O2.

At this point, there are a couple of choices. We could modify the input to raise it to our decimal scale, or we can modify the output to change the display. And there's another consideration. We need to be able to adjust the sensor reading each day we want to test our mixes. Sensors as they age can creep up or down. Also, humidity and temperature can have an effect on the sensor as well, so we'll need to be able to calibrate, so we need a rheostat (which is a potentiometer used as a variable resistor).

How do we do it? We need for 100 to show up when there's 100% oxygen. All we do is find the range of our sensor for air, knowing that it needs to show 20.9 on the meter and make what the voltmeter thinks is 100mV be the max mV. We're going to move the range down (or up if there was a sensor that read >100mV on pure O2). Whatever sensor you use will have a specification for what it reads in air, or pure O2. We'll take that value to calculate what the reference value needs to be in the panel display.

Let's say our sensor reads 13mV on air, which is 20.9% oxygen. Since the panel reads 100 for 100mV, we want it to read 20.9 when it is at 13mV by changing what it thinks '100' should be. We just get this ratio, so 13/209 = 62mV.

Now using our formula above in the current divider, we need 20.9 on the meter to be associated with our input of 13mV, which means at 'reference', or 100, it needs to be 62mV. Let's assume R4 (the built-in adjustment rheostat) is centered at 100.

3000mV-Vref=V * (R2 / (R2 + R3 + R4))

Vref is our reference voltage
3000mV is the input voltage
R2 is our 'big' resistor which knocks the voltage down from 3V to where our readings live
R3 is the value we're solving for
R4 is the built-in adjustment on the panel (100)

3000 - Vref= 3000 * (30000/ ( 30000 + R3 + 100))
2938mV = 3000 * (30000/ ( 30100 + R3))
R3=(3000mV * 30000Ohms / 2938mV) - 30100Ohms
R3=533 Ohms

So, let's plug in our value at what our sensor will read in air and see what the output will be. The voltage that it reads is 13mV and it compares it to 62mv. 13/62 is the ratio with the '100' reference. So it is a percentage of 100....drumroll 20.9!

Now you may ask yourself- well, you just adjusted our sensor for air- what about if I only know what it reads at 100% O2? Not a problem- the ratio for our target mV is exactly the same. If we want it to read 100 at 100% O2, we need to know what the sensor puts out. Check your specifications, but most list it in air (and guarantee the linearity). So, we'll say that our sensor which reads 13 in air, will read 62mV (100/20.9 * 13). See a pattern? That's what we just fixed our sensor using 20.9 and 13mV.

Note that we can also change around our reference voltage by changing the R2 or 'big' resistor. We could have left the other resistors and calculated for R2 instead. In our case, our oxygen sensor puts out <100mv,> 100mV on some sensors, in that case, we'd shift it the other way and choose a larger R3/4/5 or smaller R2.

The above is the modification needed to allow the use of any oxygen sensor with a panel meter. Just by changing the value of the voltage divider, we reset the 'percentage of 100' that we want to use. When we calculate what 100 should be, our voltmeter now translates it into percentage of oxygen.

Now we know what to pick for R3 (or R2) to meet our needs. The next thing we need to decide is how to adjust the reading. R4 is a screw-adjusted rheostat which is used at the factory to set the voltage reference level (especially if the other resistors are a little out of spec). We could use this resistor, except that it's only accessible inside the panel's enclosure. The reason we need to set the reading is that the oxygen sensor tends to drift its base value over time. We need to reset it on air before we do other readings. We've got two choices- change the R3/4/5 resistor value by introducing another rheostat (R3/4/5..6), or change the voltage level of the measured voltage by putting a voltage divider on it.

Since a voltage divider can only lower a voltage, it is better that our adjustment rheostat be in the centering circuit, since a value can be chosen which allows it to be adjusted up or down, instead of just down in the case of the input voltage. Therefore (and as is shown in the oxy hacker book), the R3 resistor we've chosen should actually be two- a rheostat, and a fixed resistor. A 100 Ohm rheostat will give enough adjustment, and can be put in series with equivalent resistors, or a larger rheostat could be used, with a finer adjustment ability.

A Lethal Slayer of Fish

2009-08-26T12:52:00.001-07:00

I've been fortunate to have a run of good weather, and accommodating friends which have allowed me a lot of diving lately. And either my luck is getting better- or my fish-finding skills are. I'm consistently bringing back big- and many- fish to the boat. To the point that I think I'm getting more invites because I've been generous sharing the fish.

I filled the boat's limit on grouper by myself recently- and managed to get the assorted other fish, sheepshead, triggers, and snapper to get the mixed-bag. Hogfish have eluded me, but I'm hoping to get another invite from Killer and Griller to fill that 'shelf' in the freezer.

I'm feeling a bit embarrassed with my run of luck lately, as I've been on the boat with a bunch of out-of-towners, who have been very complimentary of my fishing skills- to the point that one of them exclaimed I was a Lethal Slayer of Fish. A bit of hyperbole, but I'm very flattered.

The Compressor Saga begins

2009-04-13T20:43:00.001-07:00

SCUBA diving has now surpassed racing as a hobby. And to feed the insanity and the engineer inside me, I've taken the plunge and gotten a Mako KA-7 compressor.

List of what needs to be done:

Wire up 220V
Set up 3500 and 4500 banks
Build a mixing panel
Set up O2 cascade/bank

Here's an attempt at what the fill station should look like

A racing report from the past

2008-09-14T08:34:00.001-07:00

Billy, if you're out there, give me a shout (you wanker)...

From: Bill Brownsberger <bbrownsb@comsys-opg.com>
To: Motorcycle Roadracing Listserver <race@micapeak.com>
Date: Wed, 11 Mar 1998 09:21:20 -0800
Subject: A backmarker's view of the 200

Hey everyone!

I resubscribed to The List to tell you all what a horrible
time I had at Daytona this year! Let me start by saying that
the AMA just doesn't have the Average Joe in mind when they
run this event, which really pisses me off! Come on, this
is supposed to be the biggest race in the country, and if
it isn't open to everyone, regardless of their financial
backing, then something just isn't right.

My week started off well enough, after almost a year's
hiatus, I really felt like I was getting back into this
roadracing thing with the right attitude. Since I've sold
off all of the racebikes, I walked out to my garage to
peruse my possible mounts for the weekend:

'86 VFR 750 - nahh, I'd hate to scratch the paint while dueling
with Russell and Duhamel
'94 ATK 406 - nahh, I just rebuilt it, it needs more break-in
miles on the trails before I can flog it
'84 RZ 350 - nahh, it only runs with the choke on
'94 KDX 200 - this will have to do it, it'll give a little
away up on the banking, only making about 25hp,
but I should be able to make that up in the infield

Race prepping consisted of shaving the knobbies down bald,
and of course the obligatory safety wire. We're there.

The AMA officials gave me some weird looks as I headed out for
the first practice session, most of them told me that the
supercross practice didn't start until later in the week.
Idiots! The KDX is an ENDURO bike, far from a supercross or
even a motocross bike. The sheer ignorance of some people amazes
me. I saw Laura Hardy directing some bikes out onto the course, and
made a beeline for her. She must not have recognized me, because as
soon as she saw me, she looked the other way. Oh well.
Once past the officials and onto the track, I started
to really blow those cobwebs out, and quickly got up to speed.
My wife was my pit crew, and she would yell my laptimes through
a bullhorn as I went by. You can't imagine the sense of
accomplishment I had as my laptimes lowered. I started off
doing :58s, then :56s, and before I knew it, I was down around
the 4:50 mark. I'd always heard Russell talk of getting into
the "forties" and figured I wasn't far off, I just might have
something for these guys come Sunday. I did think it strange
that most everyone had at least 100mph on me on the banking,
and they even went by quickly in the infield, but I must be
making time somewhere. I was waiting for SOMEONE to come by who
I could race with, but I guess Zack Jones's truck must have broke
on the way to the track. A few of the guys on superstock bikes
stopped by my pit to congratulate me on doing so well in
practice, it seems they were really glad to have me around.
Everyone loves a winner I guess.

Rather than make the 45 minute drive home that evening, I
decided to sleep in my van that night, and hang with the superstock
crowd, I figured this would let them know that I'm just as
needy and deserving of a 200 entry as they all were. We
sat around, drank cheap beer and lamented the fact that none
of us had the money to buy big-rig bike haulers or those
fancy-pants slick tires that some of the top riders had,
but we knew deep in our hearts that Daytona is the place
for us, and you can keep all of those "support" races, we
ain't nobody's underwear! And NASB? Forget it, the 200 is
the ONLY race we need mess with, Go Big or Stay Home! Sam
Fleming and I did get into some interesting discussions about
what lines to take on a bike making less than 140hp... I was
surprised that Fred Fartzignewton didn't show up, but then I
remembered that those high-horse AMA elitists only want 'experts'
and pros in the race. I told them that 5 years of racing is more
than enough to make you an expert, but they still want that piece
of paper! I even called Fred and told him that he needs to come
and argue his point, but he declined, saying that he'd rather
not race against guys who have been on a racetrack before, especially
if he can't protest everyone who beats him... Andy Birko came by
all of the non-factory-guys' pits, and kicked sand in our faces,
telling us to get the hell out and "Stay the fuck off the track!"...
Other than that, he seemed a likeable guy, although his
190lbs looked pretty funny on a 125.

Well, to make a long story short, it turns out that I didn't
make the cut for the 200, and boy am I pissed! How can they
deny me the right to race? I know that I may have been a little
off the pace, but come on, I can't afford the expensive tires
or 3 brakes like those other guys! Just because I'm a little
low on funds doesn't mean I shouldn't be allowed to get out
there and mix it up a little! I know I would have impressed
some people in the race, I really come alive once the pressure
is on. I don't mean to toot my own horn, but I did win
my fair share of regional races ya know, so I know I've got
what it takes to run with these spoiled punks.

Next year...

Billy B.

PS: If that Scott Russell flicks me off 1 more time...

The Deathstick Tastes Blood!

2008-07-26T16:22:00.001-07:00

Carpooled down to Harker's Island with Pete, aka Silent Killer on Friday but we got a really late start, not getting the boat out until noon. I wolfed down a couple of hotdogs from the gas station when we were gassing up- and ended up with chilidogs instead of my mustard/relish/slaw. The chili looked a bit 'experienced', but I was hungry.

The seas were a bit rough on the way out- and overcast. But the forecast called for no wind, and maybe a chance of showers. We were worried about vis because for the past week or so, there has been a layer of cold green water on the bottom. Silent Killer sneakily suggested I drop first when we were out at Big 10. The water looked beautiful on top. I started down and at about 40' started to get vertigo because I could see- but not the bottom. Sure enough- at around 60 it was like diving into a greenish cloud. I aborted because vis was all of 10 feet. I did a quick bounce on another spot and found structure and about 15' of vis, but nothing but juvenile fish.

We decided to head further out with the hope of better visibility. Good choice! SK drops on some great structure- but says the vis was just okay. He comes back with his biggest snapper of the year. He said he found a hole with three spiny lobster, so I grab my old gun and clip a lobster loop and bag to it. I back drop the spot and vis was amazing compared to the soup I was on earlier in the day. I manage a good gag, but the big fish were keeping well out of the way. Never did see the lobster.

Due to the generousity of Ken Jones of Deathstick Spearguns, and Spearfishing Planet, I was lucky enough to win a recent contest and had a beautiful custom-made Deathstick with me. I really wanted this first dive with it to be a successful one, but didn't have it rigged yet to be able to carry my plethora of crap with me when I was lobstering. Yes, I'm one of those divers who has everything. Trust me, it pays off.

SilentKiller drops on the submarine wreck out there. There are big grouper on it, guarded by bigger sandtigers but he came back up having only seen one grouper, and none of his buddies. It was more of a 'gotta dive the sub' event than a spearfishing one. He said the vis on the sub wasn't as good as the ledges we were on, so we head back to where we were. We marked a bunch of spots while I was waiting for my surface interval. My nitrox mix was light for the depths we were diving so I was getting close to deco on my drops. If anyone wants giant amberjack, come to NC. Some of these were as long as I was. I used to think they scared the fish away, but I'm of the mind now that it makes the big fish curious. About every dive, we found ourselves in the middle of a swarm of them.

Remember that chilidog from paragraph one? I do. As I puked it up in dead-calm seas, SilentKiller gives me some words of wisdom: never eat anything that's two-for-two-dollars while diving.

I dive again with my old gun (still hoping to get a lobster), and nail a snapper and struggle with getting him on the stringer, so I load up my 2nd shaft hoping some big fish will come take a look at the commotion. I pull back on the band and the gun slips off my hip. I figure it must have been pressing against my computer or something. I try again- and it happens again. Talk about timing- my old 3-piece gun is so worn that the trigger housing is flexing when I load up the 2nd band. Great. My new gun is on the boat. Of course, I spot some big grouper so I go up and tell SK where they are. He drops in and grabs a nice scamp, but the big boys stayed in the sand. We're not far from a spot where we spotted some huge grouper, and I still have half a tank from the early drop in bad vis.

I decide I need to give the deathstick a chance- it's just been on the boat looking pretty while I screw around with my old (and now broken) gun. I drop in on the spot, but don't see much. I'm hanging pretty far off the bottom, trying to save air and deco. A few big guys are out there, but I don't have the time to play hide and seek. I'm very bummed- my new gun is going to come back unblooded.

I go up really slowly because of the earlier close-to-deco. The vis is simply amazing at 20 feet of depth- I can see forever. I look around at the amberjack swimming below, enjoying the last dive of the day (and the first dive day in a month!). And I look again. Some of those amberjack look funny. THOSE AREN'T AMBERJACK! Screw it, I'm going back down. At about 50' I get close enough to the swarm of Cobia. There were at least 9 of them flying in formation. My gun was unloaded since I was coming up, and I struggle to get the band pulled back. I only get one band loaded, even though I'm going to be line shafting a long shot. One of them way down is a monster, and the one closest to me is legal, but dwarfed by the others. I split the difference and dive bomb on the next biggest (and closest one). I stretch way out, take careful aim as the cobia are starting to swim away. I purposefully didn't go for a head shot, but just behind it to hopefully get a solid hit. I aim, and the laser-accurate Deathstick delivers as promised. I see the shaft go through the fish enough for the flopper to stick, and I go straight up, not wanting a fight at this depth and with my computer bitching at me. I wrap the line around the gun a few times so I have a solid lever to pull on and look down and see what the cobia were after. A huge stingray was just sitting on the bottom and the cobes were just milling around above him waiting for the next buffet line to start up. I go up to the boat (still relatively slowly) and the cobia cooperates by swimming in circles below me.

If he'd swim up, there's a chance he would throw the shaft, so I'm happy with the situation. I make it to the boat and yell for SK that I have a fish. He's looking at me kind of weird because all he sees is my gun. I slowly reel the fish up to me, grab the spear and the Cobia goes apeshit. I'm holding the spear and the fish is kicking so hard that the 5/16th spring steel shaft is flexing back and forth. I stick the tip of the spear out of the water and yell for SilentKiller to help get the big boy in the boat. He grabs the gaff and hooks him and the fish calms down. He asks me to take the spear out before he pulls it in the boat. I was really hesitant because if he kicked off the gaff, I could still have a chance of grabbing him with the spear. I pull the spear out, Pete hauls the fish in, and what ensues, I can only describe as some kind of nautical cage fighting. I'm still in the water, and I just hear Pete cussing and the fish flailing around. It reminds me of that scene in A Christmas Story where the kid describes his dad as a furnace-fighter. After what ensued, the fish not having a spear with which to toss around was probably a very good idea. The scuffle finally stops by the time I get around to the ladder. As I climb up, Pete is sitting on the fish cooler, a good third of the fish sticking out of it. He says to me "sit on this thing so this fish will die!" There is blood all over the boat. I'm not sure of the battle that ensued after the fish went up, but I'm glad it is only the cobia's blood. Pete goes to grab a brush and start scrubbing down the boat and I'm getting my tank off when the fish goes nuts again, jumps out of the cooler and thrashes around the boat. Cobias are well known for causing damage when they come on the boat 'green'. Pete's yelling "stick something in it!"- so I grab my stringer, which has a sharp point on it and jab it in the side, and step on it to pin it down, then grab the knife off my BC and stab him in the head, hitting off-center the first thrust and then sinking it between the eyes. That did it- finally. Just in case, we leave the knife in a good while. The boat is filled with even more blood. I ask for a photo op to show off the new gun, but we only have Pete's camera-phone. No matter, as you can see how thrilled I was to take home my second-even, and biggest Cobia.

Spearfishermen- heck, fishermen in general consider Cobia to be "the best-eating fish in the ocean."

Pete was on a mission to get his own Cobia after I explained that there were a large group of them just milling around the ray. He grabs my tank and BC, which had about 720PSI in it so he can take a look. I turn on the pony bottle for him, so if he does get something, he's not pressed for air.

I'm hopeful he'll get a fish, and I idle around following his bubbles, but he comes up empty-handed. The ray- and cobia-escorts had moved on. I've seen giant rays before, but I really need to concentrate on looking 'up' to see if there are cobia waiting for a meal. Apparently, when rays swim along the bottom, they stir up all kinds of creatures in the sand that the cobia love to eat.

We spend a little while cleaning up, but we've got a long way to go to get home. Fortunately the seas were beautifully calm. But, it wasn't going to help- even though we were running flat out in ideal seas, the sun was going down faster than we were going in. We get to the difficult channel run to the Harker's Island boat ramp, and hit sand. Pete jumps out and it's knee deep. I have too much gear with me as usual- but my pair of dive lights come in quite handy to spot the channel markers as we slowly make our way back. It was a late night, getting home but getting the cobia made the trip!

Cornerspeeding

2008-07-14T21:34:00.000-07:00

It's been a while, but I went back to the racetrack with Cornerspeed this year. I had an absolute blast with the students. I was a bit rusty myself, but by the end of the day I was back up to speed. However, the brake gremlins were still after me. Russell actually bought brand-new rotors for me to test out- and they helped with braking- but by the end of the day, the lever was coming back to the bar again. I don't know what else I need to do. My reputation for deep braking is ill-deserved, as it is because I can't get the bike slowed down!

Interstate Champion

2008-06-27T08:48:00.000-07:00

In the highstakes game of interstate cash-only, probably illicit spearfishing tournament, it's anyone's guess who ends up on top.

HOD

2008-06-18T05:10:00.000-07:00

The term 'HOD' is thrown around spearfishing websites a lot. It is one of those 'in the know' abbreviations that if you have the ask, you won't ever know. I figured it out without asking- and then brought one home.

I'd like to present my first 'Hoop of Death', or 'Hoop of Doom!', or a big stringer of fish shot on one dive.

It was unusual in that big fish are found in deep water. We were pretty shallow, diving on an artificial reef composed of big concrete pipes. It was a perfect habitat for the fish- and for the hunter as well because you could look through or in the pipes for fish. However, the site we were on apparently had very few divers on it- because the fish were not skittish. I 'back-dove' the site after the resident flounder expert Scotty cleaned up.

I started the dive swimming into a current and spotted one of my new favorite fish- a Tautog. I shot him and put him on my stringer, then swam towards the center of the pipes when I swam over a big flounder and scared him off the bottom. I added him to my stringer and continued to the center of the pipes. I see a nice grouper and shot him in the pipe he was hiding. The line I have on my gun is in disrepair, so instead of trying to pull him through the pipe, I shoot him again with my second shaft, swim to the other side of the pipe, then push him back through. The commotion that all this did brought several fish up who were curious. As I was stringing up the grouper- a second grouper shows up and I shoot him too. Wow! So far, I've covered very little ground, as the fish seem to come to me. I start to move to the end of the debris field when I spot a really big grouper on the edge of it. He's just lazily swimming into the current. I decide to drop my stringer behind him and make some noise to get him to investigate. I hid behind a piece of pipe and wait...

Two legal grouper come to take a look and I keep waiting for Mr. Fatty. No go.

So, I figure at this point that he's oblivious to the world; leave the stringer, and figure I'll go high above him and shoot down on him. Nope. Soon as I get up and behind him, but well out of shot range, he heads off into the bare sand ahead. I look and see there are only two pieces of concrete ahead, so I figure he'll be in those. I go back and move the string back to his exercise spot, hoping if he gets spooked back to it that he'll check out my other fish. When I'm done, I swing far to the right and swim about a 45 degree angle approaching the larger piece of pipe. I swim just high enough to look over it and see him in his shining glory. I drop to the bottom and army-man to the other end of the pipe that he's on. I start blowing bubbles- I think I had been holding my breath (bad scuba diver, bad!) on the approach. Sure enough, Mr. "I forgot about the sea monster chasing me 5 minutes ago" Grouper takes a peek into his new concrete pipe and just stares at me with 'who the heck are you?'. Mr. Spring Steel to you, buddy! I put one through him and he takes off- I'm worried about my line breaking so, instead of trying to take a second shot over the piece of pipe, I swim through the pipe, out the other side- and he wasn't as active as I thought. I grab him hard by the gills, grab my gun and swim back to the stringer.

I find my way back to the anchor and shoot a black sea bass- a small, but delicious fish. At this point, I have a mixed-grill of seafood and am ready to go back to the boat when I find I lost my extra spear I carry with me. I do a lap around where I thought I had been but never found it. But, this spot was so good, I think we'll be back and hopefully I'll find that spear again. Losing the spear was nothing compared to the achievement of my personal-best HOD.

New River Rendezvous

2008-05-21T09:04:00.001-07:00

The New River Gorge is one of my favorite places to climb- easy access, all kinds of climbing, and a great community. They have a celebration every year and I finally made one this year and had a blast!

Slaying fish!

2008-05-15T06:54:00.000-07:00

This is a first- I consider myself a novice spearfisherman. But, on a trip on Ken's new boat, I was slaying the fish.

He bought a fantastic dive boat for a project of his and wanted crew members for the move of the boat from Southport to Morehead city. And he mentioned that maybe we'd get some diving in.. was I interested? In a word... Yes! The seas were beautiful but since it was a new boat, we took a very conservative path relatively shallow along the coast. We tried to hit a 'rock' but ended up in the sand. We were still getting the feel of the electronics in the boat. We then hit a wreck on the way in which was really beautiful- but devoid of fish.

We decided to hit a spot called Big 10 Rock, which is really a large area full of coral mounds. It reminded me a lot of the middlegrounds- except on this trip it was filled with fish! The depths were pretty shallow and the fish somewhat scarce, but I ventured over where we anchored to the right where there was more relief. The fish were a bit frightened so I decided to look under the ledges- bingo! A big grouper was mine. I put him down hoping to interest other fish, but he was the only one I brought back- 32", though I'm not sure of the weight. On the way back, we hit a scary inshore wreck- vis was 8' and the water was pea-green, but I shot a big sheepshead.

The next day we went to an area Captain Leroy said was a 'half-moon'. I think we found it, but we were on the down-current side.

I swam up and down this ledge, not seeing many fish, but then out in the sand, a big grouper shows up, but turns around. Since there weren't many fish where I was, I decide to follow him. He led me to fish-paradise! There were so many fish swimming around, I thought I was in an aquarium. I was a terrible shot, missing a lot of fish, but I knew this is where we wanted to dive. We did a second dive on it and I got two grouper, and thought I hit a third one under a rock, but it was silted up- and my spear was stuck. I sent up a marker on the spot so I could come back and get my spear. I had to meet up with the boat since I didn't surface at the anchor. A few mechanical issues later, I back-dove the spot to get my spear- and fish- but there was nothing but a spear there. It was a very successful trip, and looking forward to more.

No Ice Needed

2008-01-20T08:32:00.000-08:00

With the newest kid coming in February, I wanted to get some fish home before I was relegated to daddy-duty. I tried going out the end of the year, and twice in the new year, but got blown out both times. Finally, the weather held enough in mid-January to give it a shot. When I called, I found out that the boat had three more on it, so we were a go!

I had been skunked, or almost skunked my last two times out, so it was important that I bring home some fish! The wife was complaining about the cost-per-pound of fish, so something had to be done. The problem was that there were a lot of men in gray suits hanging around most dives and they seem to like the same fish I do. I resolved to get some fish home regardless.

The day started out pretty dreary- snow was due back in Raleigh on the way home. Captain Leroy had the satellite picture, but it was incomplete because of the cloud cover the past few days. It did look like a patch of warm water was to be found on the 'east side', so we headed that way.

Since there were non-spearos on board (all but me actually), he decided to hit the Atlas Tanker first. The girls had done this dive with me before, plenty of big grouper, but it had some giant Sand Tiger sharks on it last time. I've gotten to the point of not enjoying going into the water without my gun, so I brought it with me even though I wasn't planning on getting fish. Unfortunately, the visibility was terrible. The water was cloudy on the surface, and it got darker on the way down. When I finally got to the wreck, I had trouble telling the hull from the walls of baitfish everywhere. I swam up and down the wreck for a while, not seeing many big fish, but some Tautog, and some big Black Sea Bass- not worth an encounter with the taxman. Finally, at the bottom near the bow of the wreck, I scare up two good sized sharks, and see a third one later in the dive. I thought I knew where the anchor line was, but couldn't find it. So I ascend nearby and find myself pretty far from the boat. It was a long swim back in some decent (3-4) seas, and when I get onboard, I decide to get rid of my Hardees breakfast. I was out of dramamine, so I had bought some Bonine at the shop and took it on the way out- too late, apparently. Ugh.

The captain was disappointed with the reports of visibility and temperature. It was 63 on top, and in the 50s on the bottom, with 10' of visibility. Captain Leroy was somewhat at a loss, because everywhere else should be colder and less vis. He mentioned that there was a small wreck not too far away where he could drop me (less shark potential) and then take the other guys back to the Atlas if they wanted. The wreck is called the Amagansett. I think everyone was tired and cold, so they all decided to jump in the water with me to get it over with.

I went down the line quickly this time and was greeted by an upside down wooden hull. I peer over the edge and see three decent sized (amazing how 'decent' moves upwards the more fish you shoot) grouper and immediately shoot the first one with my re-rigged line spear. I stoned him, which was good. I put my dud powerhead on the second spear, and sure enough, a big sand tiger comes by. I nail him with the dud and he swims off- I'm wanting to bring in some big grouper to take a look at their buddy, but instead a second sand tiger takes a look. I give him the same treatment and head to the surface with the fish dangling below me. I get to the boat and give Leroy the fish on a spear, but it won't come out- I hit the spine and the tip lodged there. He unscrews the spear, and takes the line off my gun and I go down with just my freeshaft. I move a bit forward and see a really nice (30+#) grouper at the edge of vis and follow him a bit and come up on some juvenile sand tigers who are just stupid. I poke one away with my speartip, then shoot another black grouper. I unhook my stringer from my gun- but forgot to shoulder my gun, and it goes shooting up the water column. I chase it for 20', then decide not being bent and coming back with a fish bonus should be worth the loss of the gun. I manage to find the uneaten and stoned fish on the bottom with my spear firmly through it and swim back to the anchor. Meanwhile, I'm feeling like I've got a shishkebab grouper and am tempting the gray suits. I see two of the guys on the dive with me and sign-language try to ask where the anchor is- they don't know either. It had come unhooked! The cold (50 degrees!) water has done a number on the LCD display of my computer- I can't read it- so I probably go up way too quickly. This time I'm closer to the boat, get back to it with my shark-bait, and ask if anyone's seen a speargun float by. Leroy spotted it, so I jump in and swim to it.. yay! I get back to the boat, tired, but not too tired to blow chunks again. The vis was better here- closer to 20', but the cold water was brutal- when my computer warms up, we'll see, but I think it was 50. I actually was warm enough in my new semi-dry 7mm with 5mm hood.

This trip would have been lousy- except I got some decent fish!

And the cold water ensured the fish were fresh- and the white stuff everywhere kept them cool while cleaning them.

No ice needed!

Winter Spearing

2007-12-14T12:53:00.000-08:00

After a stellar day diving with my daughter on Saturday, and the continued amazing weather (80 degrees), I called up Discovery Diving on a whim on Monday and found out there was a boat going out the next morning. I emailed Captain Leroy and he said he'd be able to drop me on a decent ledge between wreck dives so I could try for some fish.

Since the 'burban is acting up with the transmission, I dusted off the RX7 and drove down way early Tuesday morning. I was early and just hung around waiting for others to show (and took a nap). The others got there eventually and I grabbed some HP100s from the shop and we loaded up. I have ended up on the boat with some very cool people lately. I guess these cold(er)-weather divers are a lot more cool than the typical underwater tourists, because I've really enjoyed meeting them. The guys on the boat this time were three guys from Winston- a 20-something couple and a guy a little older than me. Considering we were all taking off mid-week to dive, there had to be a story- mine is that I have too much vacation left and had to burn it anyway. The guy of the couple was in a rock band, and his gf was in school. The third guy was a DOD employee trying to get some diving in before going back to Afghanistan and doing drug interdiction flights. He had flown his own plane down to Beaufort- and has invited me for future flights when he gets back- how cool is that?!

Our first dive is the U-352, a German U-Boat that was sunk by the coast guard. Those were some hard-core sailors in those days- that thing is tiny. Which meant that I didn't have a lot of opportunity to get fish because there's just not a lot of structure. There were some fat grouper about 20' off the sub, but no chance to get near them. There were also some big sand tiger sharks hanging out, of which we got a few pictures. I found out later that the secret is that in the bow, there are holes where the big grouper hang out. Next time.

Leroy dropped me off on a deep ledge that had a good show. I was hoping for some lobster to put in the freezer. The dive was looking like a bust- I burned a lot of air at 120' for 15 mins, with only small fish around.

On my lap back down the ledge I saw a decent triggerfish (he's featured in my post on trigger cleaning) and stoned him cold. I really didn't want that- I wanted a bit of a twitch to maybe bring out some more fish. The AJs (we don't eat them here) went crazy though and got the other fish interested. I was headed back to the anchor line and saw Mr. Hog. Sweet! I was pretty far off the bottom to save air, so I took a shot from too far up, I hit him, but it wasn't good at all. He goes beserk, and an 11#+ fish can move. But the jacks were my friends and they followed him to where he holed up, and I followed them. Then came a dilemma- a huge grouper comes out and is checking me and the fuss around the hog out. I had my second shaft loaded- but what to do - the hog was not dead, and I had plenty of grouper already in the freezer. I really wish Steff was with me because she's hit that big grouper while I dealt with the hog. "A bird in the hand is better than two in the bush" went through my head so I decided to put the second shaft into the hogfish. Well, he's not moving anymore- and I string him up- and I see two more big grouper come out... but my spear won't come out! I've got the big hogfish stuck to the end of my speargun and am running out of air. I switch over to my pony tank while I mess with it for a while, but no luck. I'm going to have to come back to the boat with a fish stuck to my gun, leaving some big boys behind.

I get back to the boat to find an 11# hog to go with my triggerfish and a mackerel we caught while trolling. A decent mix for sure!

I sit out while the rest of them drop in on the Spar. I'm kind of glad I didn't stick with them- they came up scared. Said they got swarmed by sharks, which started bumping into them. No chance for fish that drop for sure.

We get back to the dock and I drive Jeff to his very nice plane for him to fly home. That's a cool way to go. When he gets back in-country, we'll see about taking some trips!

Spearit Charter

2007-03-16T15:55:00.000-07:00

My buddies from Florida were doing a trip to the NC Coast because they heard about the big fish- and shark teeth that we have up here. Teresa, Wayne and John drove to Topsail Island and we met up with Captain Tom Collins

Powder in SaltLake

2007-02-25T18:29:00.000-08:00

We really lucked out this year- doing the annual Rougetide snowboarding trip to Salt lake City this year. We decided to hit Solitude- and were greeted with snow all day! It was the best conditions I have skied! More pics and updates to come!

Dry SCUBA diving

2007-02-15T10:45:00.000-08:00

It's a riddle. I'm going diving- but not getting wet. I'll be putting an entry into my dive log, but won't be near the ocean?

I'm participating in a DAN and US Navy-sponsored study called 'Flying after Diving' held at the Center for Hyperbaric Medicine. This research is important to me because I was in the Navy once-upon-a-time. These days, having to wait 24 hours before flying really cramps your vacation schedule.

The particular study was an aggressive one. We did a 60' dive for 2 hours- that's a decompression dive, so we 'came up' to 10' for 26 minutes for decompression. We then had a 3-hour surface interval, followed by a 4-hour flight.

The dive itself is pretty sketchy- I don't like being out of control. You're in the chamber- just hanging out- and air starts rushing in. You're having to equalize- and pretty often. I think I was doing it too often because only every-other pre-squeeze resulted in my ears clearing. The part I didn't like was that you don't have control of your descent- it is a controlled rate. When I'm diving, if I have problems equalizing, I'll just stay at that depth for a second or go up a little bit. This ride is straight down- though they told us to let them know if we can't equalize for some reason. The absolute weirdest thing was speaking- it was like we were on helium (Donald Duck voices)- but we were just breathing air. I was embarrassed to speak because the deeper your voice, the greater the effect. It was just because of the higher density of air. They told of experiments to 2000+ feet where divers couldn't understand each other from this effect. They actually had to use headsets to lower the frequency to communicate.

Once at depth, the lights went out and we watched a movie. Pretty cool- they hang a sheet on the far end of the chamber, and use a little projector through one of the portholes. The movie was 'The Big Blue'. It's French. Here's an excellent summary. It was actually not the best movie to see while testing for decompression sickness.

Anyway, we ate lunch during the surface interval (and used the head, sheesh!) walked around and such- and then back to sealab.

This was the 'dangerous' part of the experiment. They test shorter and shorter intervals at sea level before you fly. 12 participants had already done this dive without DCS. We nine were part of a study group to help finalize this test as 'passed'- the next test will be with a two-hour interval.

During the 4-hour flight, every 30 minutes during the flight they would use a doppler system to test for bubbles passing through your pulmonary artery into your heart. Since there's less pressure at 8000 feet, a gas (Nitrogen) will come out of solution faster. Nitrogen in your tissues first starts showing up in your blood as the blood circulates around the tissues. In the case of flying, the lower pressure might cause it to come out of solution in the form of bubbles instead of a controlled off-gassing. The painful part is when it shows up in your joints (hence, the bends). About 1.5 hours into the flight, I started having bubbles observed- as did pretty much everyone else. They use a fancy stethoscope (doppler ultrasound) which transmits a fixed frequency and listens for the return. Bubbles make a swishing sound a trained technician can detect. They rate the bubbles from 0-4 with 0 being nothing observed and 4 being the sound of bubbles is louder than the sound of the heart valves themselves. Doing some amount of physical activity forces bubbles out of your muscles and joints and into the bloodstream. We would flex each arm and leg, rotating the joints, while the technician listened. If bubbles were found, we then had a second test where a doctor used an ultrasound to examine the chambers of the heart. That was very interesting- watching your own heart. What they look for in that test is to make sure that no bubbles are seen in the left-chamber of the heart. The right chamber is what pumps the blood to the lungs where they do an excellent job of filtering the nitrogen. If any make it back into the left chamber- DANGER- that means bubbles are headed to the brain. For some reason, every time I flexed my left leg, I'd get bubbles of grade '3' every time, all the way to the end of the flight. I had to even get tested post-flight to make sure the bubbles subsided. I was back to zero on all the tests 10 minutes after the flight- but it was a real eye (ear?) opener to see the real effects of a gas coming out of solution. But, I- and everyone else- passed- because we didn't get DCS.

I got some good data for myself. Exertion really does make the bubbles form. There would be no bubbles at rest, but I would almost spike when I flexed my muscles. Take it easy on your surface interval and after your dive. Once bubbles form, they slow the off-gassing because the nitrogen clusters around the bubbles, rather than desaturate. I also learned that older (I was by far the oldest diver- bunch of college kids were the rest) male divers are more prone to bubble formation (but not necessarily DCS). And, it is known that fat absorbs much more nitrogen than lean body tissue- I'm happy that at 17%, I was less fatty than several of the 20-year-my-junior college kids. Probably the biggest risk factor is a condition (read the DCS link) where your heart has a hole between the chambers (left over from the fetus). Most of those that have had DCS had this condition. I'm pretty sure that my effervescence, but negative on the right-side-heart shows that I'm safe as far as that.

For me, it is going to make me a tad more careful about planning my trips (no fricking way will my 'passing' a 3-hour interval before flying make me try it).

There are a bunch of other studies coming up with that I might try as well- I really pumped the doctors and staff for information and got some good info. For example- the doctor kind of discounted the 'hydration' thing as a huge factor in DCS- compared to time and depth. On the other hand, if you are damn cold before you start a dive (everyone is cold at the end of a dive), you're much less likely to absorb nitrogen into your tissues during the dive.

Really cool bunch of guys to go 'diving' with- you get a little pocket change, you help the science of the sport you love, and you get to sit around, eat food and watch movies and BS with a bunch of divers- without getting wet.

Minibike madness!

2006-12-07T12:28:00.000-08:00

What do you do in the off-season? Well, make something an on-season. For motorcyclists, dirt bike riding starts in the Fall because the cooler temperatures make riding in the dirt fun- and on the street... cold!

I've got a dirtbike, but I rarely ride it- it is a lot more bike that I can handle, and I don't have a regular group I ride with because I'm often climbing- or lately scuba-ing on the weekend.

Cornerspeed is starting up a new training tool- Cornerspin. It is flat-track technique that all the biggest names in roadracing learned. Basically, you take an underpowered motorcycle (XR100), throw some street tires on it (Bridgestone Trailwings) and then ride it on a groomed track.

Aaron of Cornerspeed built a track North of Charlotte and had a curriculum- but wanted someone to test it on. So, the instructors of Cornerspeed were invited to a weekend of riding on his track.

The girls had an XR100 from last year (and never rode it), so I went ahead and prepped it for the event. The track is only two hours from the house, so the plan was to get up at 6 and drive straight there. Wrong. The fracking truck wouldn't start. Something is wrong with the batteries- because it has a new alternator on it. HOURS later, it finally charges and I get to Cornerspin at 2pm.

I was not in my element- the guys had lessons all day and were 'backing it in' to the fast corners, and spinning out of the slow ones. Wow. I rode around and got passed a lot. I also got lots of dirt in my mouth. The guys were beat, and we quit early. I got a few tips about body position and such and tried it for a little more, then we went into Charlotte and ate dinner at a fantastic Malaysian/Indian/Japanese restaurant (I'm not kidding).

The next day was more like it- we did drills in the morning which were to work on a technique, such as riding with the bike as LOW as possible. Then we worked on sliding around the corners. It was an absolute blast, now that I had some idea of what I was doing!

I fell down a half-dozen times, but was well-armored. I wore my old racing leathers, and my racing back protector, and my off-road kidney protector. Originally I wore my motocross boots, but they were so heavy- I wore beater roadrace boots the next time out and it was much bettter.

I'm still trying to put together if there's going to be a direct influence on racing, and I think.. not. Towards the end of the day, I tried to corner by hanging off- it was bizarre- and unsettling. Roadrace techniques don't work on the flattrack- and most flattrack won't carry over to roadracing. However, I believe it is the subconscious of feeling the bike slide that is going to help in the long run. Hopefully, I won't put my foot on the ground when I'm bent over at VIR!