Need a power supply design for STM32 based PI detector

[cristiano.sar]

I have found the problem. These breadboards have the power rails divided at the middle and that was the problem. Added some jumpers and now it works.

The Preamp output waveform:

[cristiano.sar]

Now I have another doubt, in the attached 2 images, the best preamp null should be when the DVM measures the most near possible around 0v?

Preamp null at 2.3v



Preamp null at 32mv



My doubt is just because in the first image, the wave form looks better than in the second case, in which the preamp null is near 0v.

Thanks.

[cristiano.sar]

Here is a small vídeo of it detecting for the first time, no my plan is to improve the code and use a better ADC than the 12 bits infernal one