Question about tgsl

[waleed]

Hello everyone,I just finished soldering everything (all components are new except the ICs from the old pcb) I made the EDU silverdog mod,and then I attached the coil and when I powered up the device it just continue beeping without stopping even when I connect the TX alone but it just continue beepin until I remove the TX coil it stops. I didn't test anything yet because the multimeter with my friend I'll get it soon, but what would cause this problem for now??, I'm really disappointed because it's my second time making this device without success :/

https://i.imgur.com/Dw4reO3.jpg

https://i.imgur.com/cvzOUqc.jpg

https://i.imgur.com/T2STfp8.jpg

[waleed]

Great. That is the PCB I bought to build the TGSL. Mine has been working great and have added the Roderico VDI graphic display. Spent four hours park hunting today with it.

Cool man I wish I get mine working as well.

[waltr]

Hello everyone, I'm just so happy cuz the TGSL-EDU pcb arrived , I couldn't shipping it to my country it wasn't on the list,so I had to shipping it to my cousin in Australia and she sent it to me via Australia registered mail, I'm glad that I got it today.
Anyway I'll start to make it once I get all the components and then I'll post feedback about it

https://i.ibb.co/dpp3D35/20200208-190303.jpg

Great. That is the PCB I bought to build the TGSL. Mine has been working great and have added the Roderico VDI graphic display. Spent four hours park hunting today with it.

[Nandor]

Happy soldering!

Use IC sockets, it's a very good metal detector to build.

[waleed]

Hello everyone, I'm just so happy cuz the TGSL-EDU pcb arrived , I couldn't shipping it to my country it wasn't on the list,so I had to shipping it to my cousin in Australia and she sent it to me via Australia registered mail, I'm glad that I got it today.
Anyway I'll start to make it once I get all the components and then I'll post feedback about it

https://i.ibb.co/dpp3D35/20200208-190303.jpg

[Nandor]

LOL do not try that stupid thing!

change the 2k2 resistor from the oscillator with a 5k trimmer and adjust the TX voltage as you wish!

[ripsdevala]

Thanks, will try it

[waleed]

Dbanner, is there a way to reduce Tx current by pot? need to adapt with high mineral terain

10ohm resistor parallel with 100ohm pot, connect it series going to the start of tx coil, you will not need more that 10 ohm to reduce the current.

https://i.ibb.co/XkHvRGY/paintastic20200104-124140.png

[ripsdevala]

Dbanner, is there a way to reduce Tx current by pot? need to adapt with high mineral terain

[waleed]

I really appreciated your help guys, you always give me inspiration to continue working up, I'll not give up until I get it to work, and btw I just purchased the TGSL-EDU from Silver,beside my old project I'll build another one with the edu mod also, btw do you have the 10" DD coil details?

[dbanner]

You have an intermittent connection from the coil to the pcb. Check the coil cable and the soldering. Touch the circuit all over the bottom side with your finger and see if you don't get a beeping response. I think your circuit is fine, just some poor connection somewhere.

Once you have sorted that out, the only thing remaining is to set the coils correctly (nulling and phase), then everything will fall into place quite nicely.

You must tap into your third eye and meditate. Take things one step at a time, methodically check things. Be meticulous.
This little circuit is a baby's food, you are big iron man. Are you gonna be defeated by such baby circuit, no way!
The pathway to success is littered with many failures.

I gave myself such pep talk, when I built my first TGSL, which took me one week to even get a single beep! I made horrendous self made PCB, and drilled hole in my finger too! When I finally got the thing working properly, I looked like a man who had been through hard times.
I'm glad I had those experiences, now I know the secret to a successful project is good PREPERATION. otherwise you may need PREPERATION H.

[waltr]

What you exactly mean by this and which pin of FETs to test to know if they are turns on ?

The FET GATEs.

Omg this device really confused me, I tried it just now in my home with my low battery (it needs to be charged) and the device just worked and it start to detect metals and 1 euro coin at 20cm and it was quiet (no beeping when touching), I played with the small loop and the depth increased a bit, but the disc didn't work, I don't have a ferrite slug yet to adjust the ground balance. Anyway I'll wait to sunday when I go to uni to make sure first I have the correct resonance and the deepest null with the correct phase shift between tx and rx, because I think disc channel won't work until I have the correct phase shift.

Something very weird is going on. Usually something very simple and explainable once you find it.
This does take lots of persistence and patience like any electronic troubleshooting.

Without ferrite use a silver coin. Adjust GB trimmer until silver coin not detected in AM mode, then back the GB trim until it is detected.
The GB trim is normally adjusted with both ferrite and a silver coin so that ferrite is rejected and silver is not rejected.

[waleed]

Oki I'm done with it, just tried now to test it again to see if it still working and the same problem back again (no sound at all when moving a target on the coil) only beeping when power on. Now I'm pretty sure that my coils are oki and the problem is with the board itself or maybe some joints are not soldered properly.
I may buy the TGSL-EDU pcb from Silverdog, and rebuild it again with a good soldering.

[waleed]

Omg this device really confused me, I tried it just now in my home with my low battery (it needs to be charged) and the device just worked and it start to detect metals and 1 euro coin at 20cm and it was quiet (no beeping when touching), I played with the small loop and the depth increased a bit, but the disc didn't work, I don't have a ferrite slug yet to adjust the ground balance. Anyway I'll wait to sunday when I go to uni to make sure first I have the correct resonance and the deepest null with the correct phase shift between tx and rx, because I think disc channel won't work until I have the correct phase shift.

[waleed]

The wave forms look fine. RX is noisy due to electrical noise in you shop. My RX signal looks worse than that but TGSL works great.
I have read that with a concentric the RX phase shift is about 200 degrees.
Again use both channels of your scope to compare when the FET switches turn on relative to the TX and/or RX signal phase.

Next is check the outputs of the next two amps, U103 pins 1 & 7, then U104-6 & U105-7.
These should be very near to Zero Voltages.

Did you try All Metal Mode?
I am guessing it still beeps when powered on.

It did take me a while of fiddling to get my TGSL working. Keep at it.

I'm really tired man but I'll not give up, I really wish that i can get it to work at any distance of detection I'll be satisfied, anyway yes I tried it in all metal mod and the device still beeps when power on and I'll check the poins you mentioned above when I back to uni because we are off until Sunday (I do test the device there because I don't have oscilloscope),

And I read this in the document "If the disc channel agrees with the ground balance channel at the
same instant, we have detection!".but how to know if the disc channel agrees with ground balance channel how to test that?,

Again use both channels of your scope to compare when the FET switches turn on relative to the TX and/or RX signal phase.

What you exactly mean by this and which pin of FETs to test to know if they are turns on ?