El Cheapo II

[Warhammer]

I've seen comments on this unit on other boards, and the concenus is generally good. Since I'm in the market for an analyzer, I thought I'd ask my trusted buds. What's your opinion on this unit?

Here's the link:
http://www.oxycheq.com/

 

[Mario S Caner]

I can't really say that I have much experience with them. I need a sensor as well, so I guess we'll be learning about this together. I do know that plenty of people like the OMS unit.


The Mk15/CCR-1000 looks like a bargain! Closed Circuit Rebreather capable of 1000feet for $7000! By the way they advertise it with "analog electronics" which is an oxymoran that's new to me. LOL!

 

[Warhammer]

LOL!! Well, I know what analog electronics means in my line of work. You basically have 2 types of electronics, analog and digital. Digital being the newer of the two. With digital, everthing is done electronically but with analog some things are done mechanically. More confused? Me two. In my line of work, which is scales, it means it either has pods that you turn for adjustment (analog) or all adjustments are done through the indicator (digital). That's about the extent of my knowledge.

 

[joewr]

Warhammer,

I will talk to a couple of analytical chemists and see what they know about this concept. In principle, if you build something like an O2 analyzer using good plans and care, it should do just fine. I will check into the chemistry/physics that they are using, too.

By the way, "analog" instruments measure in a continuous fashion--like old fashioned speedometers, etc. They can also be "electronic"; e.g., ammeters (usually labled "BATTERY") in cars. "Digital" meters measure in discrete increments. They are sorta like little adding machines. Most pressure gauges on dive consoles are analog and dive computers are usually digital (There are analog computers, but I have never seen one in a dive console! But if there is, I will learn about it soon from the considerate members of this board!).

Before the true geeks get on my case, I will confess that the above is an oversimplification! But it is not bad for a guy who learned how to program when Fortran 4 was the state of the art!

Hey, Warhammer, do you stay up nights thinking up this stuff???? There is probably a place for you in Silicone Valley!

Joewr

 

[daylight]

Warhammer, you may have seen my comments on the "other" boards, so I'll provide you a different perspective.

I am very pleased with my El Cheapo II Analyzer. The directions were easy to follow and accurate. The guy at Oxycheq answered any questions rapidly and completely. It almost seemed like he was looking over my shoulder and coaching me along.

Cutting the case to accept the components was the most tedious, but the instructions are very accurate. i may have been oerly cautious but i didn't want to mess that up and make it look like a homemade kludge. The final product looks almost identical to a commercially assembled analyzer.

Use solder paste and wick to remove the surface mount resistor and solering the leads for the pot. This was the most awkard part of the assembly. The Oxycheq guy can't get discrete component circuit boards, so you have to work with the surface mount components. The second circuit board came out perfect after I ruined the first one.

I tested my final product against two commercial products and had identical readings when measuring two different mixes. All in all, I am vary pleased with the end result and like having my own analyzer.

 

[Warhammer]

Joe....Nope, but I do stay up rather late. Silicon Valley sounds good to me, more money = more diving!

daylight....Thanks for your input. I hadn't seen your comments elsewhere, unless you go under a different name elsewhere. Everyone I've heard of so far has liked it. Do have a question. I assume since it's user assembled that you can also change the sensor when it goes bad? I was also eyeing the OxySpy for that purpose.

 

[daylight]

Warhammer,

No, I don't use any other name for boards. Sorry, I have responded to some queries on other boards regarding the El Cheapo II and I mistakenly thought you may have been one of those.

Yes, the sensor can be changed. I also sprung for the coiled cord for connection from the box to the sensor. The one that comes stock with the analyzer is sufficient but the coiled cord give you a cooler analyzer and longer reach. The connection is phono mini-jack on each end.

Enjoy,

Larry

 

[Mario S Caner]

So... how much are we talking here? And would one of you capable one's care to build one for me?

 

[daylight]

You need to check their site at http://oxycheq.com
The best I can recall, I spent about $150 for the analyser with sensor, coiled cord, shipping, 9 volt battery, and a dry box to store it in. I think this is about 1/2 what they retail for. The sensors alone go for $85.00 So, I think it is a good deal.

 

[joewr]

Warhammer The Curious:

Well, I checked with some analytical chemist pals using the info supplied by "El Cheapo" manufacturer and they said that the Teledyne sensor is the same breed that many analytical labs use in commercial O2 analyzers. They use a special property of O2 that is based on its electronic structure (Do you want to hear about unpaired electrons? Probably not!)Further, from what they could tell, the plans look reasonable.

So, assuming the company is legit, the El Cheapo should do the job. One warning: it is not as robust as a commercial analyzer and will not take as much abuse. Also, be sure to calibrate it regularly.

Calibration is simple. Have your friendly dive shop make you up a "Pony" of the gas mix you normally use (e.g., 34%) and keep this sample in a secure place. If you use more than one mix, bracket the range with at least two samples. Prior to doing a test, check the analyzer with the known sample(s). Keep records in a note book and check to see that the sample analysis remains constant--so, if the O2 goes from 34% to 33% to 30%, you know the Pony is leaking--although how air would go from a low pressure environment to a high pressure one is not clear. However,if the analysis goes from 34% to 33% to 34% to 33% you just have statistical "drift". You should refill and reanalyze the Pony fairly regularly--say, once or twice a year depending on how much you use it.

Another thing...be a good craftsman when you build the kit--neatness counts!

Joewr