GM module evaluation report (module modification suggestions)

阿萨骨头

GM module evaluation report (module modification suggestions) [Copy link]

Recently, I asked the editor for the circuit diagram of this module. At first glance, I focused on the switching power supply design. . . The BOOST circuit does not consume much power, and it is a tiny power supply. It is a bit of a waste to use an MT3608 as a power chip. The maximum output voltage of this chip is 24V, the maximum current is 2A, the performance redundancy is relatively large, and the price of a single chip is about 1 yuan, which is a bit expensive. Our single-chip system usually has a 5V power supply, so it is not worth it to draw power from 3.3V to power the module.

Then there is the BOOST design. It is a common design to triple the voltage to 400V. The added feedback diode can also effectively reduce the heat generation of MPSA42, but the filter capacitor is too small. The 10nF capacitor will cause ripples in actual measurement. Here we usually use 1uF MLCC to suppress the ripples, otherwise the detection noise will be slightly large. I suspect that some higher count rates are caused by the fact that the MLCC is only 10nF. However, part of it is caused by the use of BOOST power supply. The nuclear detector part must not use the switching power supply as the power supply, otherwise it will increase some background noise.

Let's take a look at this 555 pulse width stretching circuit. There is an obvious problem that the pulse width stretcher is too wide. At high count rates, the buzzer will sound long. When I took the UF4 sample for testing, it almost sent me and my labmates away. It was too noisy. I suggest that the pulse width stretcher be shortened. Otherwise, the buzzer will not be able to distinguish the dose at high count rates. . .

There is another very important issue. Our circuit board design and shell design will cause half of the GM tube to be unable to detect radiation. The circuit board should have windows to allow rays to pass through, and the bottom of the shell should also be left empty in this place.

This is the end of the module modification suggestions. I hope the designers will consider them carefully.

Finally, the circuit diagram of this scheme is attached.

小生意

Xiaobai said that he was confused and didn't understand it at all. Just take a look