Magnum on steroids!

[Gwil]

Again, interesting. The Rx may not be tuned to the Tx frequency but I'm pretty sure the Rx coil and C1 form a series resonant circuit. If the coil inductance was 5mH the input current would peak at a little above 10kHz.
If I've got this wrong I hope someone will explain how. (it's been a long time since I studied AC theory)

[ivconic]

Thanks, very interesting. However is the Rx really untuned? Doesn't the Rx coil and the 473 capacitor form a series tuned circuit?

It is untuned obviously. At Golden Mask models you can change TX freq. by simply changing C in parallel with L. Rx remains unchanged and works almost the same.
Those are working at 7,8,12,15 and 18kHz just fine with the very same RX.

[Gwil]

Thanks, very interesting. However is the Rx really untuned? Doesn't the Rx coil and the 473 capacitor form a series tuned circuit?

[ivconic]

Can anyone tell me if there is an advantage (or disadvantage) in using a Magnum type common base amplifier as the first stage of the receiver, rather than an op amp?
Thanks.

I noticed interesting thing coincidently; even when TX is not connected; RX will still work!? It will detect ferrous objects at decent distance!
Iron pliers is detected at 40cm in air! With strong audio response!
RX is untuned, wideband. Tolerant. Low impedance input and high impedance output.
I guess it is much easier to make it work in diy arrangement. Very sensitive.
I would ask the same question to Dave Johnson about indeed splendid solution at 1225, 1235 and similar RX frontends.
At SMW exactly that part is taken and copied from 1225.
Later on i made version with opamp front end just to see the differences. Original 1225 version was superior in all the aspects.
Solid state rules!

[Gwil]

Can anyone tell me if there is an advantage (or disadvantage) in using a Magnum type common base amplifier as the first stage of the receiver, rather than an op amp?
Thanks.

[bandito]

Is this a surface mount board?

yes

http://www.geotech1.com/forums/attachment.php?attachmentid=37895&d=1479839866

[multieagle]

Is this a surface mount board?

[bandito]

Pcb for Magnum -13 euro+free shiping

[ivconic]

[bandito]

They are ready if someone wants to write

[scs]

I have noticed that when the detector is Hartley oscillator runs deeper. I can not understand why.

[Toros]

Yes.

Skinflint

[scs]

Yes.

[ivconic]

I have detector better "Deus".My construction, only for my hobby.

Excellent!
From your previous schematics and works i am sure that you are not talking empty talks here.
I guess you are not very ready to share it here?

[scs]

I have detector better "Deus".My construction, only for my hobby.