Question about tgsl

[waleed]

Thanks guys for the reply I really appreciated it.. yea now I'm sure that I have placed them wrong so I'll test them first for integrity then I'll placed them the right way and I'll see what will happen

[waltr]

Note: I used PN2222 instead of 2N2222 but I think that i have placed the two transistors on the tx coil wrong maybe i have reversed emitter with collector idk

Check all transistors for proper orientation. You have to also test them for integrity, as putting them in the wrong way could potentially cause damage.
Check the transistors for the voltage inverter.

Yes, different make transistors do have different pin outs.
This is a huge problem for beginners and persons with lots of experience. This has gotten me a few times.

A transistor tester, many DMM have this feature, or the diode scale on your Ohmmeter can determine the pin out. Look for the emitter to base diode.

The TGSL's oscillator will run with a wide range of coil inductances.
So issue is most likely the transistor pin out.

7.9V instead of exactly 8V is no problem as this is simply the tolerance of the 8V regulator's output.
The negative 5V MUST have the oscillator running.

First step is getting the oscillator running like you are trying to do.

[dbanner]

Check all transistors for proper orientation. You have to also test them for integrity, as putting them in the wrong way could potentially cause damage.
Check the transistors for the voltage inverter.

[waleed]

Note: I used PN2222 instead of 2N2222 but I think that i have placed the two transistors on the tx coil wrong maybe i have reversed emitter with collector idk

[waleed]

Hello there..well I connected the tx coil only (I don't know its inductance exactly but same n of turns and 24 ohm) but when I turned the device on nothing happened I mean there is no sound at all..I checked the 8v it was 7.9 I think no problem, but I don't have the negative 5v it was 0.79v. Also I checked the output of tx coil on the ac settings but it didn't give any output on the oscilloscope.
I think the problem with the tx coil Idk..and how do I measure its resonance frequency on the oscilloscope

[waltr]

Correct, you need at least a TX coil to have the TX oscillator running.
Then check the -5 (-6.2V) power.
Next check the outputs to the JFET switches.

I wound a 100mm diameter coil for bench testing these parts.
Use the coil calculator for number of turns to be close to 6mH.
This works for the initial testing.

[waleed]

no, you can not. you must connect a coil and then do a test. without coil the circuit does not generate negative voltage needed for the working.
thats specific feature of this circuit.

Yeah I read before that I should connect the coils to get the -5v but I thought I can do another tests rather than that..but anyway I'll go ahead and make the coils I hope today

[kt315]

no, you can not. you must connect a coil and then do a test. without coil the circuit does not generate negative voltage needed for the working.
thats specific feature of this circuit.

[waleed]

Hello everyone..well I got some time this week and finished the board. But before I make the coils I would ask if I can make some tests just to verify that everything is working well or at least the board doesn't contain any broken components

[Boadil]

Thanks!!!!!

[ripsdevala]

Yes. You can put threshold pot here as in pic. I did this mod and it worked very well. I had more control over the sensitivity. It is just the same with the pantera and silver sabre schemes. So now the first pot is called SENS and the new pot is called THRESH.

Thanks a lot dbanner

Will add to the neglected board.

[dbanner]

Anyone know how to add gain pot connection? Need to reduce gain for high mineralised soil... Beeping everywhere

Yes. You can put threshold pot here as in pic. I did this mod and it worked very well. I had more control over the sensitivity. It is just the same with the pantera and silver sabre schemes. So now the first pot is called SENS and the new pot is called THRESH.

[ripsdevala]

Anyone know how to add gain pot connection? Need to reduce gain for high mineralised soil... Beeping everywhere

[dbanner]

Good answer dbanner

Sometimes, on rare ocassions, I do get it right.

[waleed]

Thank you for the useful reply..I will post when I finish the board and make some tests..