two box problem

[jskalitexnis]

HI,
i have one metal detector two box
tinker-rasor 711-T
https://reibert.info/threads/glubinn...htanga.363191/
And I have a problem with the receiver.
The variable coil is absent and not work.


I would like someone to have the machine say the coded coil to repair it.
else If someone has the circuit

The coil is something like this

[jskalitexnis]

https://www.google.gr/search?q=varia...8t3vkqp4REOzM:

[jskalitexnis]

nobody???

[Skippy]

You are not explaining your problem well.
Your google link shows 1000's of different variable inductors, big, small. Show us a photo of the inside of your machine, where the missing coil is situated.

I think your machine may be a variation / copy of a Fisher Gemini-3. You may be able to find information on this machine more easily.
https://www.kellycodetectors.com/catalog/gemini-3
http://www.fisherlab.com/hobby/fishe...l-detector.htm

I found this, maybe it helps?
http://forum.cxem.net/index.php?/top...sher-gemini-3/

[homefire]

Could this be your Machine ? http://www.bonanza.com/items/like/218400613/Vintage-Detectron-Metal-Detector-Model-711

http://www.tinker-rasor.com/detectron/

http://www.curtcass.com/detectron/index2.html

https://articulo.mercadolibre.com.ve...-t-anos-60-_JM

[Skippy]

Some more Gemini-2 stuff here, and Gemini-3 transmitter:
http://www.geotech1.com/forums/showt...rcuit-Gemini-2

There's a Gemini-3 receiver pcb photo here, I didn't look through the whole thread. It shows a 10mm TOKO coil (for the tuned amplifier) , and then there's the transformer for matching the RX coil to the receiver amplifier.
http://www.geotech1.com/forums/showt...0-2-boxxxx-%29

[jskalitexnis]

The problem is . This variable coil is corrupted. And I do not know the replacement code to replace it.




The machine operates at 12.5 kHz

[jskalitexnis]

The outer casing is almost identical to the gemini 3. But the circuit is different.My own does not have 1 ic
The outer casing is almost identical to the gemini 3. But the circuit is different.My own does not have 1 ic

[Skippy]

You have the coil, that is good. You just have to work out what is wrong with it (it may not be faulty) and repair / rewind it.

Often, the wires inside these transformers can fracture, as they are very thin. Corrosion can also make them break. Open up the transformer (remove the outer metal can) and examine the points where wires are joined to the main pcb pins. Use a multimeter to measure resistance between the pins, they are usually less than 20 ohms

If the transformer is really damaged and not repairable, a likely replacement would be a Toko 10PA series coil, custom wound.

[jskalitexnis]

The cables are cut off. Only 2 out of 5 I find. But it is different coil.
It makes me feel that no one has this detector

[homefire]

Novel Idea. Call them and ask ? http://tinker-rasor.com/products/det...ruments/505-2/

[jskalitexnis]

Novel Idea. Call them and ask ? http://tinker-rasor.com/products/det...ruments/505-2/

tnx homefire.I contacted. They claim they are old and they do not have the circuit

[Skippy]

How do you know the machine operates at 12.5 KHz ? Have you measured the transmitter output?

I think the reciever circuit is going to be similar to the Gemini-2 circuit. You are going to have to do some reverse-engineering to confirm this. You need to work out the connections to the coil on the PCB. If you took some good photos of the PCB near the coil it would help.

[jskalitexnis]

How do you know the machine operates at 12.5 KHz ? Have you measured the transmitter output?

I think the reciever circuit is going to be similar to the Gemini-2 circuit. You are going to have to do some reverse-engineering to confirm this. You need to work out the connections to the coil on the PCB. If you took some good photos of the PCB near the coil it would help.

I measured the output transmitter with the frequency meter. And I searched it in the radio. At 12.5kHz tuning.
the gemini-2 ciruit ?

[Skippy]

Sadly, it doesn't look like the Gemini-2 at all. It's going to be a hard job to get this working. One thing I see is 5 connections (or maybe 4) to the transformer, the Gemini has only 3. You could possibly take to pieces the coil windings, counting out how many turns there are - a difficult job. Don't do that yet, though.

The Gemini-2 operates at 82 KHz, the same as the Gemini-3, so that's another big difference. And I can't see any input transformer going between the receive coil and the PCB. ( The other transformer on the PCB is for the audio output, to the headphones / loudspeaker, I think).