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HV measurement

A project log for Geiger counter

Radiation measurement device w/ Raspberry Pi Pico and STS-5 tube

florian-wilhelm-dirnbergerFlorian Wilhelm Dirnberger 11/12/2022 at 13:342 Comments

Simple HV measure arrangement: consisting of four 82V Zener diodes, one 10 MOhm and one 2.2 MOhm resistor (series connection). These are parallel to the tube Anode and GND.

The Voltmeter is parallel to the 2.2 MOhm resistor.

On the picture you see a voltage of some 11V, what means the HV amounts in this case to:

HVtube = 11 + (11/2.2)*10 + 4*82 = 390V 

(actually it is slightly higher since the Voltmeter has an internal resistance in the 10 MOhm range what affects the measured value)

Varying the PWM parameters in the SW would lead to higher and lower voltages, respectively.

The assembly described here could be the basis for a control loop design.

Discussions

biemster wrote 11/14/2022 at 17:04 point

That's a great way to measure the HV, I did not see this before. I never got around to building something that can actually measure this on my board, this circuit is now high on my TODO list! thanks!

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Florian Wilhelm Dirnberger wrote 11/15/2022 at 04:58 point

Thanks for your reply biemster, I appreciate it!

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