DIY Touch Screen Trimix Analyser

[stepfen]

2: you can see the buck converter on the main PCB - it's the component that outputs 3.0 volts.

Indeed, I was unaware of this particular board hence I didn't know/notice it can be supplied from the battery directly. My bad.

 

[stevetto]

Nice! I didn't look into ESP yet - the use of a touchscreen requires a lot of memory, which is a real issue using an Arduino.
Curious to see some screenshots. I have one of those touch screen display's but I think they're quite dim, colors are not bright and it's difficult to read the screen outside in sunlight.

2: you can see the buck converter on the main PCB - it's the component that outputs 3.0 volts.

ESP32 is much powerful than arduino nano but the lcd refreshing is still challanging.

 

[stepfen]

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[Jarek Andrzejewski]

Does volume (speed) of flowing gas impacts the helium reading or it doesn't matter?

 

[stevetto]

Does volume (speed) of flowing gas impacts the helium reading or it doesn't matter?

You are right! The speed of flow influences the reading of the thermal conductivity sensor.
And the pressure in your tank influence the flow rate.
To minimize the error you can:
- use low flow rate
- use a constant flow rate flow restrictor (flow is constant regardless of the tank's pressure)
- fix your flow restrictor at a certain position and always analyze full tanks (same pressure same flow rate)
(the flow rate is viscosity dependent, and viscosity depends on the mixture)
( calibration and analysis has to be made at the same flow rate)
- or you might can fill the chamber with gas, wait the readings to stabilize, stop flow, cover the exhaust holes, wait a bit and maybe you can get better results

I do not know how big the influence of these factors. It need to be tested.

 

[stevetto]

 

[stevetto]

3D printed and painted case

 

[stevetto]

It has not been calibrated to Helium.
For nitrox I use 3 points calibration.

 

[stevetto]

 

[stevetto]