Can pinpointer detecting thin chain?

[Fabian]

Is 33nf. I tried with lower and higher values and only the sound and the engine speed was changed, but kept running backwards.

[Nupi]

What is the value of C2?

[Fabian]

I put two 100k and then a 330k resistor in series with VR1, and always beeps continuously.

[Nupi]

mistake

[Nupi]

Put 2 from 100K or 3 en try

[Nupi]

*************** PP - UPDATE ****************
******************************************

[Fabian]

Hi Nupi.

With a 100k resistor constantly beeped all the way of VR2. I tried lower values and with 56k beeping stopped, but it works "backwards" as before

[Nupi]

Sorry, NOT parallel but in sequence with R1

[Nupi]

It all looks very good, excellent.
But I think that capacitor C2 is not a MKP but MKT (I hate mkt)
Put in series to R1 a resistance of about 100K if it does not workyou put two resistor 100K
series to R1.
Please try
nupi

[Fabian]

Hello Nupi.

I rotated the wires, (Once again, I had already tried) and not working at all ... I can not understand what is happening ... I did the coil rotating in the same direction, the values of the elements are fine ...

some photos

[Nupi]

Hi Nupi. I continue doing coils. I got the following values:

2.7 Ohms / 1.58 mH for L1

1.5 Ohms / .330 mH for L2

At the junction of R5 and C4 I measure 4.18v maximum

And the PP works "backwards". When it's working, approached a coin and stops ringing ... I suppose it's for the difference in resistance, Can that be the cause?. I think I need to get copper wire of different gauges to follow.

Any tips?

Regards,

Fabián

Swap with L1 and L2a and try again.
I wait
nupi

[Nupi]

Hello nupi,

This is a good instructional picture. Nice and clear. Is there anyway we could make it easier to find ? Maybe start a Nupi Pinpointer thread ?

Anyway thanks for your work.

I do not know what is better. To open as you say A new thread I have no experience. Maybe someone can advise me on this.(Qiaozhi?)

[Nupi]

which function of R1 and R2

"Simply explained" With R1 and R2 set you the bias point for the detection point in.
It is a class-C oscillator.Bias point moves as oscilation begins due to build up of
voltage across the emitter resistor.Bias point moves as a target whent too the coil.
The oscillator will draw more current and you get a voltage drop across R3 and is detected by the Ic.
There are several factors that play a role in the operation of the pp.
The theme (which seems) can you read on the page 34 of the interesting book "inside the metall detector"
from George Overton and Carl Moreland.
Maybe this picture better clarified.
nupi.

[Fabian]

Hi Nupi. I continue doing coils. I got the following values:

2.7 Ohms / 1.58 mH for L1

1.5 Ohms / .330 mH for L2

At the junction of R5 and C4 I measure 4.18v maximum

And the PP works "backwards". When it's working, approached a coin and stops ringing ... I suppose it's for the difference in resistance, Can that be the cause?. I think I need to get copper wire of different gauges to follow.

Any tips?

Regards,

Fabián

[Fabian]

Okay, Fabian Do not look at the old pictures, but only use this.
If you have any questions you can just ask.
nupi

Thank you very much, Nupi. I'm working on it. When the detector is running achieved, I will show the result.

regards,

Fabian