gold gun al707 or 718

[abdou2014]

expert parameter, I need your diagram , don't stop searching

[Geo]

Until now i did n't find full schematic...
The only that i found is the frequency selector.
Varicaps have capacitance between 20 and 500pF (if i remember ok).

[abdou2014]

thank you very much, we are missing only the receiver circuit and meter

[Geo]

Here is what i found from true rms meter.
There is n't schematic for receiver but it is the same as prototype with the difference of ic's.
I don't remember other changes...

[abdou2014]

thank you, I will try to find time for its realization I want to know does your gold gun have a good reception from VLF stations ?

[Geo]

Yes... always it receives at least one VLF station with signal more than 200mv.
As i saw at original GG when signal was lower than 150mv it was noise so no ability to detect any object.
Also is indicated only for big targets...

[abdou2014]

does it receive when the antenna is pointed towards the transmitter or in width or in both cases ?

[Geo]

I don't know who is the transmitter that it receives, i only look the meter for high signal and a narrow zero.

[abdou2014]

thanks, what is the length of each ferrite rod , wire diameter , number of turns ?

[Geo]

I use only one ferrite 20cm.
Inductance is near to 10mH per section.
Wire 0.2mm diameter
Turns... i don't remember

[abdou2014]

what's te distance between the two windings ? and the total inductance ?

[Geo]

I don't remember. Ferrite is closed in a plastic tube...
Total inductance must be more than 30mH..

[abdou2014]

Thank you

[Geo]

Originally Posted by Geo

Until now i did n't find full schematic...
The only that i found is the frequency selector.
Varicaps have capacitance between 20 and 500pF (if i remember ok).

Today i measured the frequency of each band using this selsctor.
so i have

1. 24.6 .... 30.5 Khz
2. 17.8..... 25.5
3. 14.5.....19.7
4. 11..... 12.9
5. 9.7 ......10.9
6. 6.3 ......6.6 Khz

As you see it receives directly from 6 ... 33 Khz (-10db).
So with a good scan will find a strong vlf station inside one of all these bands.

[abdou2014]

very good method I need to know the position of the two potentiometers (tune and volume) thank you

[Geo]

What do you mean????

[abdou2014]

where i connect these two pots ( tune and volume ) in the diagram ?

[abdou2014]

excuse me the tune pot is for the varicap
it remains that the pot volume which is not on the diagram

[Geo]

You must connect the other half of TLC272 to pin 8 of TL071 via 100n. Draw the same schematic with the other half and connect a potentiometer at output (pin1). Audio ampl must be at different box and far from lrl. GG is very sensitive to self-oscillations. Usyally i don't use the audio, only the meter.

[abdou2014]

Thank you

[taxma1981]

What do you think for this point?

https://youtu.be/ioXUAYkFxRM

[Pahom]

Question to all who are in the subject. I understand correctly that there are two circuits, one on the TL084 is an earlier circuit and the second circuit is on the LM324.

[Geo]

LM324 and TL074 are similar ICs. No differences for this simple circuit...
Both are quad op amplifiers.

[Pahom]

Originally Posted by Geo

LM324 and TL074 are similar ICs. No differences for this simple circuit...
Both are quad op amplifiers.

Too noisy without a signal to the station. I'll try to bypass the remaining two unused channels.

[Pahom]

And I found why it was making noise, fixed it. Cool receiver.