high voltage not working

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teus
Posts: 3
Joined: Mon Feb 08, 2016 7:48 am

high voltage not working

Post by teus »

Hi all,
I etched the board and assembled it with the correct parts. I programmed the AVR. When I short GND with TP1 I get a beep and a flashing LED. I don't get any HV, shorting the pins of the geiger tube does nothing. I checked and my 555 timer still works. I need some help to figure out what's wrong. I've never been very good with bipolar transistors, and I don't mange to figure out how the HV part works. I've spent quite a bit of time on this forum to figure out things.

I tried the circuit with other transistors for Q1, since the FJN3303F isnt tooe asy to get, this didn't work. I specially ordered FJN3303F's at another supplier, soldering in one of these didn't help.
When I remove U1 and short U1 socket pins 3 and 8 together, I measure the battery voltage on pin4.

When I remove U1 (555 timer) I get these voltages:
1 0v
2 0v
3 -0.059v
4 3.164v
5 0v
6 0v
7 -0.38v
8 3.192v

When I insert U1:
1 0v
2 1.423v
3 1.808v
4 3.157v
5 2.119v
6 0v
7 0.749v
8 3.181v
teus
Posts: 3
Joined: Mon Feb 08, 2016 7:48 am

Re: high voltage not working

Post by teus »

i figured it out, the coil's enamel wire got disconnected from one of the pins
it's working nicely now.
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