Help on vlf circuit

[Gene L.]

Was a circuit posted a year ago or so,simple vlf.Does anyone have more information like pcb photo,frequency,pin #s,IB?.Was posted on page 14 of this forum. Thank-you Gene

[Gary]

Re: Help on vlf circuit

Is this the one you want?



Click Here

[Gene%20L.]

Re: Help on vlf circuit




I believe it was this one below .

[Pepso]

Re: Help on vlf circuit

I can do PCB layout in Eagle, but question is:
is it real working schema?

[Ned]

Re: Help on vlf circuit

Yes - it really work. I made copy from original PCB and used original search head. But it was unstable at high temperatures (above 35 C). Transmit frequency is around 15 kHz.

[Chris]

Re: Help on vlf circuit

Hi Ned,

what is the name of the VLF detector?

Chris

[Ned]

Re: Help on vlf circuit

No name - it is hobbyst work. I suppose that it can be improved in many aspects.
BTW sensivity with DD search head, each 18 sm is great - 1.8 sm coin at 28 sm in ground.

[G.Gueorguiev]

Re: Help on vlf circuit

This is one of Bulgarian famous "REBEKS", designed by Grozdiu Grozdev from Varna. The original have had "8" search head!
More information you could receive via [email protected]!
Good luck!
G.Gueorguiev

[Ned]

Re: Help on vlf circuit

It's not absolutely true. I have the original circuit designed by Grozdiu (Grozdanka)and there are few similarities between this one and the original. Most significant difference is in sinchronous demodulator. Grozdiu used for this small transformers, diodes and capacitors, where this design is based on 4011 and 4066 IC's.

[Chris]

Re: Help on vlf circuit

Hi Ned

Can you post the orginal circuit design by Grozdiu into the forum? I'm sure in the forum are many who are interested and want to have a look at the original design, like me.

Chris

[Ned]

Re: Help on vlf circuit

OK, but first I should redraw it - it will take take up some time.