Full m/lab SD2000 schematics

[detecto]

"SD2000" (kinda)
-STM32F334MCU
-Digital version
-New power supply
-New front end
-ADC + comparator triggering time.

Weekends work in progress...

[detectormods]

Replace the 3 earth field adjustment trimmers with digital interface pots and auto null, then it will behave better if the frequency / pulse lengths are changed, also change manual ground balance to automatic, this is easy to do with a pump the coil to the ground detector. I have made this work and just by changing the pulse timing set the detector is as good as any out there if not better.

[Andrei]

"SD2000" (kinda)
-STM32F334MCU
-Digital version
-New power supply
-New front end
-ADC + comparator triggering time.

Weekends work in progress...

Cool! So maybe you can lay out a diagram, we'll discuss it.

[detectormods]

Manual or automatic ground balance?

[zohir]

Hi
when I measure the voltage of the power supply, I obtain -4.94v and +5.1v with a 2mhz quartz, but when I change the quartz with a value of 3mhz, I measure a voltage of -4.94v, and +6.7 v, the voltage values are normal..? and this shift between the (-) and the (+) does not disrupt the proper functioning of the op amps?

[detectormods]

By raising the frequency you are adding more pulse repetition and your feedback to control the on off ratio is not working correctly. The negative rail is linear regulated and seems to be working fine.

[kadir6141]

Max. Crystall 2.5 mhz
min.1.8mhz good working
power +- 5v stabill

[Andrei]

How do they make an automatic earth balance? You can probably do this by changing the width of the first sample(152us), but you can only configure one channel. Or additionally a microcontroller with an amplifier and two digital resistors? And where to get the measuring point? in front of a 2.2uF capacitor?

[Andrei]

Hi! I found interesting Fets DMP31D7LW-7 and DMN24H11DS (cheaper than ZVN4525G). Has anyone tried it?