Looking for a schematic for a nitrox controller

[PhillyDave]

For under $250 I built a nitrox stick. What do you charge for one? I'm not going to put out $2700 and have to charge $15 per nitrox fill to make that cost up as a new shop. No one is trying to rip off your design. You aren't the only game in town. $2700 is the rip off. I'd rather spend the time partial pressure blending then over charge my customers for your over priced controller. That's all I'm asking on here. So if you are not going to help then stay off my thread.

 

[eternaljonah]

So guys have we found some Schematics we can share
Have started to build mine and there are some great Idea's out there but a detailed schematic would be great

 

[Asheron]

Just manually add it using a regulator, needle valve, and babysit I while filling tanks to make sure the nitric analyzer doesn’t spike over 40%. That’s all my local shop has been doing for the 20 years.

The rubber duckie one would be just as much work since it looks like it’s just a solenoid that opens full bore to wherever the needle valve after it has been set to(ie neeld valve that is manually set controls mixture percentage, so it would need to be manually adjusted every time a different percentage is desired)

 

[eternaljonah]

seems rubber ducki is also out of business I can't access their website, But want to build one, got a solenoid for 10USd

 

[Asheron]

Addition to previous post.

I made the assumption in the previous post that the rubber duckie one was a solenoid on/off valve. After looking at pictures I am unsure if servo/stepper needle valve is used with a PID loop for getting exact mixing percentage.