Surf PI Micro Var. 1.00

[dbanner]

Ah, now I see that there is an smd pcb version, which is why the schematic shows BAV99

http://smartelectronix.biz/publ/obnovelenie_prostogo_impulsnogo_metalloiskatelja_surfmaster_pi_micro/1-1-0-79

[Andi68]

Somewhat confusing with the diodes I find.

These -5V are tapped at the driver stage for the mosfet

Somebody should write something that has already built this device

[dbanner]

https://m.youtube.com/watch?v=akBC8-yazo4&feature=youtu.be

https://m.youtube.com/watch?v=IWbO_VDvZwo

[BKY1337]

Are you sure that this is the same circuit? I cant see a second 14 pin IC on the board.

I flipped my diode and i got -5V without coil. But the detector still does not work.
I dont have negative voltage with coil and without mosfet.
I need to check the other chips.

[Andi68]

Are the transistors properly polarized?

to the Videos " As the bell rings the maypole spins "

[BKY1337]

I dont exactly know what you mean with polarized. I can measure 0,64kHz at the Mosfet Gate to GND, so i think they are ok.
I also know that the one for the speaker is ok because i can hear the sound.
My microcontroller sound is not the same as the one in the videos.

Problem is that i only have 1,5V negative voltage with connected coil.
I also get a steady tone which disappears when i touch the MOSFET. (without coil)

I also forgot to check the MOSFET before i soldered it in.

[dbanner]

Check your PCB track at MOSFET between drain and source, the space is very narrow, make sure it's not shorted. Even with coil connected, with MOSFET removed, you should get -5V.

[dbanner]

Also check diodes D4,D5 raising off one leg and checking with meter.
You must have -5V with everything connected.

[BKY1337]

I saw that i dont always have 640Hz pulse.
I think thats why i had 1,5 Volts.

When i have pulse the everything looks fine (with coil connected, without mosfet)
Voltages are ok.

So i decided to put OP1 back in.

I get -8V negative and 11V positive voltage when i insert OP1 (NE5534) , i used a new one for this test.

I cant test the pulse with my DSO i think i got a faulty one, i can not adjust the picture and it doesnt work always.

[Andi68]

What is the voltage at the gate of the mosfet, what is the signal at the gate?
Personally, I do not like this driver stage for the gate, and it's oversized

[BKY1337]

22,28 Volts at the Gate without MOSFET and 0.64kHz

[dbanner]

Sorry to say, but it appears that you are going around in circles.
The project definitely works.

http://vrtp.ru/index.php?showtopic=19745&st=780

Here is discussion of Eddy' project. The entire thread is dedicated to surf pi, including microcontroller version.
Use chrome browser for translation to English.

[Andi68]

https://www.vishay.com/docs/91084/sihf9630.pdf

I agree with dbanner

[BKY1337]

The voltages are always different and sometimes the pic works and sometimes not without pulse.
I think i will put the pcb aside for now.

Thanks for the help.

[dbanner]

One more thing, there was a small error with the silkscreen for D2, so you have to assume that there could be other small discrepancies. I would check over the pcb, comparing it to the schematic. Make sure everything checks out OK.
Maybe I will try to make it myself, I think it is nice little project.