Question about tgsl

[waleed]

Waltr, finally the device is working again,I changed some components to solve the problem, and I tested everything all seems good, I made the coils exactly as dbowers document (same template and turns) and the same way you did, then I connected the coil but the deepest null I reached was 0.20v I did it on multimeter not on oscilloscope, then I was able to reject ferrite then iron but I couldn't reject foil, maybe the difference frequency between TX and RX is not correct? Or the phase shift?, what would make foil not rejected?

[waltr]

Why would it not work on a perf board.
Only possibility is no load so just put a 1k-2k resistor across the harge pump output to provide a small load.

[waleed]

Waltr I removed all oscillator and charge pump components from the board, but before I replace a new components can I check for the negative voltage on a pref board?, I mean I want to test the oscillator plus the charge pump on a pref board,it will give me negative voltage? Or they should be connected on the board to achieve that?

[waleed]

?????
At this point I would need to have the circuit in my hands to troubleshoot.

The last thing I'll do is to change all oscillator and charge pump components,I'll see

[waltr]

So maybe the problem with the transistor itself?, but the the weird thing is that why TR8 and TR11 getting hot with and without the coil?, and there is no negative voltage

?????
At this point I would need to have the circuit in my hands to troubleshoot.

[waleed]

So maybe the problem with the transistor itself?, but the the weird thing is that why TR8 and TR11 getting hot with and without the coil?, and there is no negative voltage

[waltr]

The tx waveform kink is due to how the bias on the oscillator transistor changes.
There has been lots of discussion and alternate oscillators proposed in the original TGSL and IDX threads. This is why tou will see a two transistor or one transistor oscillator on various schematics. I can not explain the why.
It was finally determined that the original TGS had that kink and making a 'better' oscillator' did not improve the TGSL performance.

If you really want to know read those original threads (they are very long so will take some time).

[waltr]

Yes that what I mean, I had it earlier but I don't see it now, and I bought too many new components and replaced them but still have a problem, should I change the oscillator and charge pump components again for new ones?, I'm confused, let start step by step, first what is responsible for the little kink on the TX signal?,

The tx waveform kink is due to how the bias on the oscillator transistor changes.
There has been lots of discussion and alternate oscillators proposed in the original TGSL and IDX threads. This is why tou will see a two transistor or one transistor oscillator on various schematics. I can not explain the why.
It was finally determined that the original TGS had that kink and making a 'better' oscillator' did not improve the TGSL performance.

[waleed]

The little kink on TX waveform is what I have seen on two oscillators I built and what everyone else sees. You had this earlier, what changed??

Yes that what I mean, I had it earlier but I don't see it now, and I bought too many new components and replaced them but still have a problem, should I change the oscillator and charge pump components again for new ones?, I'm confused, let start step by step, first what is responsible for the little kink on the TX signal?,

[waltr]

But why U100 out didn't divide the oscillator frequency?, and TX shouldn't look as good as I have right?, it should have noise at top of the signal as in the img below

https://i.ibb.co/Z61fFdR/paintastic20200306-171233.png

The little kink on TX waveform is what I have seen on two oscillators I built and what everyone else sees. You had this earlier, what changed??

[waleed]

I responded two days ago but don't see my post now!!!

The scope pics show a 14kHz signal at both the TX and U100 out.
Odd the U100 is not dividing, pin 6 should have divided the Oscillator frequency by 16.

The TX waveform looks good too good as you said. The waveform out of U100 looks correct amplitude and square.

But why U100 out didn't divide the oscillator frequency?, and TX shouldn't look as good as I have right?, it should have noise at top of the signal as in the img below

https://i.ibb.co/Z61fFdR/paintastic20200306-171233.png

[waltr]

I responded two days ago but don't see my post now!!!

The scope pics show a 14kHz signal at both the TX and U100 out.
Odd the U100 is not dividing, pin 6 should have divided the Oscillator frequency by 16.

The TX waveform looks good too good as you said. The waveform out of U100 looks correct amplitude and square.

[waleed]

Waltr, today I tested TX frequency at uni, well there something wrong, see the img below, it look like a pure sinusoidal, and even at pin6 of U100 the waveform wasn't as normal, what do you think is causing this?, TR1 maybe? But I'm sure it is working good i tested it, what do you think?, and TR8,TR11 still getting hot.

https://i.ibb.co/qNwhsTK/20200305-122005.jpg

https://i.ibb.co/GQz90dr/20200305-122038.jpg

[waltr]

I checked TX frequency it wasn't normal,it was too big, maybe a cap is damaged??

Too Big as in Frequency is Too high? or as in Peak-peak amplitude too large?

For either, yes, a cap in the TX oscillator may be bad. It is not hard to damage the connection leads on many caps so a good possibility.

The charge pump trouble shooting STARTS with the TX oscillator. If this is not working properly then who knows what the charge pump will do.

As I mentioned before, I built the oscillator circuit on perf board to play with. I also wound a 10cm diameter 6.5mH coil to use for testing.
This smaller coil is easier to handle and good for just running the TX oscillator for testing.

[waleed]

I checked TX frequency it wasn't normal,it was too big, maybe a cap is damaged??