TGSL beeping when touching

[Prospekteur]

Hello,

i have build an Tgsl and it works great. But one problem i couldnt solve. It is that annoying beeping when touching cables, pots, and the housing (metal).
I have seen that others had the same problem.....could anyone help me with that problem ?

I have tested connecting shieldingcable from coil to the metalhousing too....it didnt help.

[Prospekteur]

I want to update this post again. I diddnt solve the proplem in the first post. It seems that the main problem is ground. Have someone an idea how i could solve the proplem. When touching cables and pots, especially the ground pots the detector beeps. How can i get the Tgsl more stable???

Regards Prospekteur

[Sacchetti]

I want to update this post again. I diddnt solve the proplem in the first post. It seems that the main problem is ground. Have someone an idea how i could solve the proplem. When touching cables and pots, especially the ground pots the detector beeps. How can i get the Tgsl more stable???

Regards Prospekteur

Hi!

It is normal if you are using a plastic case.
In this case it is enough to connect all potenziometer metallic case to ground using one wire for everyone.
Putting all wires to GND in one point only.

But you have a metallic case then connect GND to the metallic case using only one wire.
Check you do not have a loop.
For example, you have connected the ground signal more of one time to the metallic case.
In this case remove all GND connection and try to connect metallic case to GND only in one point.

I hope you solve the problem.

Do you are using original tessoro coil or one made from you?

[Prospekteur]

Hello,

i have changed the metal potentiometers to plastic case potentiometers. Now i have no proplems when touching the metallic case or coil cable. Only when touchin directly the pcb components i have a slightly beep. But thanks for your help. Look at this post (at #2983).....its the same method at a Delta Pulse...i think you talk about this method;-):
http://www.geotech1.com/forums/showt...ht=delta+pulse

[Koala]

Sorry bit late to the party as I had no internet for the last few day.

Had a very similar problem on a IDX build

Also turned out to be a ground loop problem.

If the PCB and coil connector are both connected to a metal box then the detector became unstable to use and touching even the coil cable make the detector sound. I insulated the coil connector from the case and the detector becomes stable.

No idea why but the factory coil was not affected only my home made.

[Sacchetti]

Hello,

i have changed the metal potentiometers to plastic case potentiometers. Now i have no proplems when touching the metallic case or coil cable. Only when touchin directly the pcb components i have a slightly beep. But thanks for your help. Look at this post (at #2983).....its the same method at a Delta Pulse...i think you talk about this method;-):
http://www.geotech1.com/forums/showt...ht=delta+pulse

Hi,
this solution confirm the problem was the ground loop on potenziometers.
Using potenziometers with plastic case you solved the problem.
It is a good workaround.

It is normal you get noise or beeps when you touch components on board when the circuit is on.

Do you are using original tessoro coil or one made from you?

[Sacchetti]

Sorry bit late to the party as I had no internet for the last few day.

Had a very similar problem on a IDX build

Also turned out to be a ground loop problem.

If the PCB and coil connector are both connected to a metal box then the detector became unstable to use and touching even the coil cable make the detector sound. I insulated the coil connector from the case and the detector becomes stable.

No idea why but the factory coil was not affected only my home made.

Hi!
Do you connect the ground inside the coil at the beginning or at the end inside the connector or both in your home made?

[Koala]

Hi!
Do you connect the ground inside the coil at the beginning or at the end inside the connector or both in your home made?

Took an original Whites 8" coil connector apart. All core are kept separate no internal links just straight through. However there is a tag on the shield pin that goes to the metal shell of the connector.

Found by accident that if this was left off my detector ran much more stable. The only way to get my detector working stable with this connected was to isolate the chassis from the connector.

Believe Tesoro coils are slightly different with the earth end of the RX and TX connected to the shield within the coil its self.

Hopefully someone who has taken one apart will confirm this for you.

[Qiaozhi]

Hopefully someone who has taken one apart will confirm this for you.

This is mentioned on page 85 of "Inside the METAL DETECTOR", and shown in Fig. 9-2.

[Sacchetti]

This is mentioned on page 85 of "Inside the METAL DETECTOR", and shown in Fig. 9-2.

But in this book is also explaind how solve the problem?

[Qiaozhi]

But in this book is also explaind how solve the problem?

I was referring to the configuration of the Tesoro coil windings, not the beeping when touching.

[Sacchetti]

I was referring to the configuration of the Tesoro coil windings, not the beeping when touching.

I understood, but what do you think about the problem when touching?

[Qiaozhi]

I understood, but what do you think about the problem when touching?

It sounds like either a grounding issue. Does it happen with the coil disconnected?

[Sacchetti]

It sounds like either a grounding issue. Does it happen with the coil disconnected?

Hi Qiaozhi!

No, it happen with the coil connected to my selfmade Eldorado (5 pin).
If I use 11" original tessoro concentric all works perfectly.
But if I connect instead this original tessoro 9"x8" I will get this problem.
I bought this as used coil in internet (ebay).
I suspect it is faulty but the seller tell me that this type is only more sensitive.
I used plastic screw to fix it as before and also the shaft is of plastic material, it is long 50cm, I think it is enough.
I can not touch the coil or his cable, I hear any vibration inside the M.D. sound for about 3, even 6 seconds or more.
I measured the coil using LCR and I have 5.7mH and 25ohm for TX then 6.2mH and 27ohm for RX.
I must remove the hand from the coil.
Also reducing sensibility I have the same problem.
I have tryed to connect the coil pins in a different way inside my M.D., also to isolate the connector but without found a solution and I do not have ground loop.
At the moment it is unusable.

Trip?

[Koala]

Sacchetti Does it also sound if you gently touch the coil cable.

If so I think you are going to strip the board out of the metal case and test on the bench.

never found a reliable way to test the shield on the bench.

Shield fault tends to be more random chatter sometimes carries on for a few seconds after moving around the coil.

Ground loop problems tend to be more a single beep if touched.


Both can be quite bad in the house an not so bad out in the field.



My detector does not like my soldering iron or florescent lights on. I had a ground loop problem which affected my homemade coil but not a factory coil.


Trouble with these annoying stability problems you can chase yourself round and round in circles. If one coil work and another does not its easy to assume the coil is the fault which it might be. But not always.