I was working on electronic part of pirani gauge a few weeks, so there were no new posts.. I moved the system from breadboard to the plastic box, added display and microprocessor. Measurement and control of the display is based on arduino.

I am not going to describe the function of pirani gauge, there is a lot of information on the web. All the electronic system is taken from this pages, I only added a pull-up resistor for wheatstone bridge, because after turning it on, the voltage on bridge stayed on 0 – both branches were equal, so now the static branch is slightly (xM ohm resistor) pulled up. I also added a atmega, low-pass filter on voltage reference, display..

Range of the gauge is from 3.3V (maximal voltage, atmospheric pressure) to somewhere around 0V. It is not calibrated yet.

Pirani gauge unit, on/off led, switch. The knob on the right is used to balance the output voltage to 3.3V – compensation of temperature and atmospheric pressure differences. The pirani gauge itself is in front of the box.

Back view, supply port on the left, pirani sensor port on the right.

inside..

I am going to place a PCB and scheme here..