Question about tgsl

[waleed]

Those Electrolytic caps are simply the Input and 8V regulator filters. No way should they be hot even if there is a short some where on the board.

Did you connect power reversed????
They Will Damage electrolytic caps.

Can you check my above comment, I added to it, and yes I connected the battery the right way I'm sure, it's the rail at 100ohm that getting too much hot,not the caps

And do you know how much your circuit consumes current?,I put multimeter from the positive battery series to the input circuit without the coil and the current was 150mA,normal?

[waltr]

Those Electrolytic caps are simply the Input and 8V regulator filters. No way should they be hot even if there is a short some where on the board.

Did you connect power reversed????
They Will Damage electrolytic caps.

[waleed]

Oki I removed U106 and U107, again I measured the output's at the Tl's the voltage was like 6v and the caps still getting hot, I really think the problem is with the Tl's, I'll go tomorrow to the city and buy a new ones,

Addition: I removed the two Tls (didn't put a new ones yet) and I removed the coil, then connected the device to the battery,but the hotting thing didn't gone, I found that not the caps is causing the heat,but the 100ohm resistor near them at the rail which connected to the +12 battery (as the img below shows),I can't even put my finger there it's too much hot, that is not normal right?

https://i.ibb.co/tbYWHZW/20200228-145753.png

[waleed]

Oki I removed the diodes near the two Tl's and check them,they are working good, I also noticed that the caps in the img below are getting hot,I checked the current of the entire circuit it was 150mA, maybe there is a short or an IC got damaged idk, I'll continue checking

https://i.ibb.co/b19DCp7/20200228-124110.jpg

[waleed]

You are in luck. My TGSL is still open and the scope is on.
Yes, both outputs are 0V with a +-100mV 60Hz (due to AC mains interfere inside the house).

If I wave my ring near the coil signals go to several Volts.
The op-amps I used are TI TL081ACP. I also have some TITL081CP.

The TI data sheet has both CP & CN as plastic 8pin DIP package. One comes in 50 peice tubes the other in 25 piece tubes with no difference in specs.
The CP & CN have a max Vos of 15mV whereas the ACP's max Vos is 6mV.

Without the coil connected both have Zero Volts at output an no AC mains noise.

Re-check everything especially soldering. Use Ohmmeter and check for shorts and also connections to other part.
It must be something simple.

The -+100mV you measured is DC right?, waltr when I overlap the coils the device gives acontinues beeping at a specific point and when I move them a bit the sound is gone, do you know what, I believe that the problem is not with Tl's, the continues beeping that appears sometimes when overlapping indicates that the problem is with a certain diode, maybe I damaged a diode that near one of the Tl's when I desolderd them? I think I applied much heat when I was desoldering, is that possible?.

[waltr]

You are in luck. My TGSL is still open and the scope is on.
Yes, both outputs are 0V with a +-100mV 60Hz (due to AC mains interfere inside the house).

If I wave my ring near the coil signals go to several Volts.
The op-amps I used are TI TL081ACP. I also have some TITL081CP.

The TI data sheet has both CP & CN as plastic 8pin DIP package. One comes in 50 peice tubes the other in 25 piece tubes with no difference in specs.
The CP & CN have a max Vos of 15mV whereas the ACP's max Vos is 6mV.

Without the coil connected both have Zero Volts at output an no AC mains noise.

Re-check everything especially soldering. Use Ohmmeter and check for shorts and also connections to other part.
It must be something simple.

[waleed]

I tried checking some data sheets and can only conclude that one maker uses CN and other uses CP for the 'same' part.
What manufacture made these?

Opened the TGSL schematic and the outputs from U104 & U105 pin6, should be very close to Zero Volts. These I am sure of since they go to the compactor.

The Negative Voltage can only be there IF the TX coil is connected to have the Oscillator and then the Charge pump running.
If you have -5V without the TX coil check the oscillator.

Are you sue you didn't put these op-amps in backwards??
I did this when I first built my TGSL. The orientation on the PCB can be in any direction so easy to get chips in backwards.

I'm sure I placed them correct,I even put back a new Tl081 but CP not CN, but the problem is the same, I'll try the Tl081CN and I'll see, I have negative 6 volt when I connect the TX coil as normal, I checked everything on oscilloscope and everything was good (disc and GB channels and the oscillator and the changing pump), but I don't know why I have 6v and -5.4v on the output of the Tl's,when I disconnect the TX the output voltage becomes in millivolte.
Are you sure the output on the Tl's is zero volte when you connect the coil and without moving any target?, can you check it, btw I checked the ampere of the entire circuit it was 150mA

[waltr]

This is really annoying, I just want to hit myself, I don't know why I desolderd the two Tl081CN's and put Tl071CP, now the device give only single beep when I connect the coil but it give no reaction at all, before it was working and now it is not, I measured the voltage at U104 pin6 it was 6v and at U105 pin6 it was -5.35v, even if I remove the coil but these points voltages still the same, is that normal?, I even placed back another new Tl081 but the one ends with CP not CN as it was before,but the problem still the same, is there any difference between Tl081CP and Tl081CN?

I tried checking some data sheets and can only conclude that one maker uses CN and other uses CP for the 'same' part.
What manufacture made these?

Opened the TGSL schematic and the outputs from U104 & U105 pin6, should be very close to Zero Volts. These I am sure of since they go to the compactor.

The Negative Voltage can only be there IF the TX coil is connected to have the Oscillator and then the Charge pump running.
If you have -5V without the TX coil check the oscillator.

Are you sue you didn't put these op-amps in backwards??
I did this when I first built my TGSL. The orientation on the PCB can be in any direction so easy to get chips in backwards.

[waleed]

I swear if I can ship a metal detector to my country I would did that long time ago instead of making one,the government forbidding such devices here,I'm really tired, anyway, waltr can you check these points at pin6 with and without the coil and tell me what you get?

[waleed]

This is really annoying, I just want to hit myself, I don't know why I desolderd the two Tl081CN's and put Tl071CP, now the device give only single beep when I connect the coil but it give no reaction at all, before it was working and now it is not, I measured the voltage at U104 pin6 it was 6v and at U105 pin6 it was -5.35v, even if I remove the coil but these points voltages still the same, is that normal?, I even placed back another new Tl081 but the one ends with CP not CN as it was before,but the problem still the same, is there any difference between Tl081CP and Tl081CN?

[waltr]

Not sure...I took those from the beginning part of the TGSL 101. I now see later He states 99 for tx & 104 for rx.
Those are more likely the turns I used.

[waleed]

The second coil was built with a Double sided form like Dbowers uses and used the exact number of turns he stated (98 TX & 107 RX).

Are you sure?, because I read he said 99 for tx and 104 for rx, he said 5 turns is always the difference between them to get the 0.5mH difference, if you used the exact same pattern as he used with same dimensions then the turns should be the same also, do you actually remember if the difference was 5 turns or what?

https://i.ibb.co/hZ4nw7v/Screenshot-20200225-234453-Drive.jpg

[waleed]

https://sites.google.com/site/dbcoil...m-style-shells

He also has concentric coil design for TGSL as well as other useful info.

Thanks, I'll remake the coils the same way you did.

[waltr]

https://sites.google.com/site/dbcoilshells/clam-style-shells

He also has concentric coil design for TGSL as well as other useful info.

[waleed]

Dbowers has a file on his web site for coil template.
I did have to play with 'zoom' parameter in the 'print' dialog to get it the correct size.
I probably print three copies that size was not correct.

Can you show me link?