Tesoro Golden Saber TGSL Problem with swinging

[Plappermaul]

Description of my problem with the TGSL circuit.

http://www.youtube.com/watch?v=K_mXZCPOCh0

When I try to "null" the coils and the RX singal is nearly 0 volts, the system start to swing around 2-3Hz after a piece of metal is moved in the near of the coils. I try out anything, but nothing helps. When the system is swinging the circuit don't react for ANY adjustment of GB, Sense or Disc. It's just beep beep beep..... arrrg.

Theese Things I already checked:

- the TX frequency ( currently at 14,45KHz )
- the RX frequency ( currently at 13,92KHz )
- try out with and without coil isolation
- try out other TX frequency
- try out a second circuit bord ( from my friend, he build the same )
- the connection cable

What me confuses is if I throw both coils on the table without any nulling and the RX signal locks terrible... the system run! and recognize on metal. But not well ( logic ;-) )

What do I wrong?
The second question is that's impoosible to get the RX signal nearly to 0 volts. The best result was 0,5volts AC. In a description it should be stay on 4mV ..??

Sorry for my bad english... in german we say I write in "Denglisch"

[paku]

nulling you coil is level same on table
dont put maskin tape and black tape
then put wire to you ground
TX have ground wire to you coil body
then on TX or RX try change wire right to left
try nulling again

[Plappermaul]

Thanks for information's.

I will try out and give a feedback as soon as possible.

Regards

[Plappermaul]

So, I followed your adwise but my problem is still present.

At first, my equipment is a voltage meter, a frequency meter and a double channel scope.

I exactly checked all cable configurations (TX, RX, both shields and all pot's connection's).

Equal what I tried, nothing has an influance of my problem.

My perceptions are:

-shields / no shields: nothing changed

+/- 5 windings: the same behavior

checked all power supply voltages (12v, 8v, -5v): in order

The pot's are working, but if the system shows the problem, I can turn the pot's in any directions but nothing changed.

After I performed setting of the coils to a minimum of 5 mv on RX with overlapping the coils, a ferrite is recognised. But i can't set the GB pot if the ferrite is rejected.

The most important notice of my test is, the system react on metal, but after a while it's starts to chattering by themself without any movement over the coils.

Further when i disconnect the RX coil during a tryout the system still beep beep beep... without the RX coil??? (sounds like video)

When I cut the power supply and reconnect, the circuit quiet a while and a few seconds later the problem starts again!!!

Maybe someone has an equal problem, or know an answer of my request, so please give adwise!

Pic's of scope or other measurements are possible.

Regards

[dfbowers]

Make absolutely sure that your batteries are good. Most often when I had that problem, believe it or not, it was the position of the speaker. Turn your speaker 90 degrees from where the coils are (not in the same plane), or just as a test, try replacing your speaker with an LED and 1K Ohm resistor in series. The speaker can sometimes act like a giant feedback loop.

[paku]

yea first check your battery then try replace IC/Chip one by one with the new
cos i have problem like that before
or without Coil Try Check You Voltage On TX And RX You Must Have Voltage on TX and RX

[Plappermaul]

First of all thanks for the quick support!

The batteries I have exchanged for new ones. Then I changed the position of the speaker (away from the circuit). Now, I replaced it with an LED.

The ICs I have all replaced with new ones. Unfortunately, without success!

The voltage (without coil) is on TX 7.55v, on RX 0.56v.

I have two TGSL EDU - Kits from Silverdog. Therefore the components should be the right.

But I'm not sure!

In both kits are TL071CN instead of the LM308. Is the TL071CN equivalent to the LM308?

I'm completely stumped!


Thanks for your patience.

[dfbowers]

TL061, TL071 or TL081 all work. Low noise, low power or low cost, take your pick. I think its the modern recommended replacement for the LM308s.
You say that you have two kits from Silverdog? Do both have the same symptoms?
Don

[Plappermaul]

Hello.

Yes, both circuits have the same behavior.

But we built these independently.

One from me, the other from a friend.

Now we have interchanged the parts ones more.

And we now know that the TL071 is the right component.

But the problem is the same.

When I try to null the coils, for example with a multimeter, like page 12 of

(http://silverdog.co.uk/shop/image/da...CoilMaking.pdf),

the circuit already starts to swinging.

But even without a connected rx coil.

Should this be so?

http://www.youtube.com/watch?v=EaI6eXReI3Q

If not, what could be my error?

Disc and shielding are not even involved at this time, I think.

An error in my setup?




I am thankful for all advice.

[Plappermaul]

Hello!

Does really nobody have an idea or a tip?

Regards

[Qiaozhi]

Hello!

Does really nobody have an idea or a tip?

Regards

You will need to debug this problem with an oscilloscope. There are just too many variables involved for anyone to deduce the cause of the problem from the information you've supplied.

[paku]

First of all thanks for the quick support!

The batteries I have exchanged for new ones. Then I changed the position of the speaker (away from the circuit). Now, I replaced it with an LED.

The ICs I have all replaced with new ones. Unfortunately, without success!

The voltage (without coil) is on TX 7.55v, on RX 0.56v.

I have two TGSL EDU - Kits from Silverdog. Therefore the components should be the right.

But I'm not sure!

In both kits are TL071CN instead of the LM308. Is the TL071CN equivalent to the LM308?

I'm completely stumped!


Thanks for your patience.

That Is The Problem Try Change Your IC LF353 And Check Your Voltage On RX Again

[Plappermaul]

Hello!

Thanks for the answers!

An oscilloscope is available, but I need to know at what point I should start with the troubleshooting.

So I have changed again the LF 353 with the other from the second kit.

But the voltage on RX is not higher than before.

Just 0.55v - 0,56v.

Can both IC's have the same error???

Regards

[paku]

yes change both other IC 308 or 393 358 Just Try And Test When You Get You Voltage On RX You have Fix That Error sound now Try Nulling Back You Coil Again

all tested without coil
when you have get voltage from RX then Try Connect You Coil And Nulling Again
make shure your coil dont have poblem
some time enamel insulated copper wire the insulated is torn with others

[Plappermaul]

Hello!


I'm still on troubleshooting and testing.


Until now, unfortunately without any new results.


What kind of voltage should be present on RX, AC or DC?


And how high they should be in the best case?


regards