Simple but effective VLF detector

[Ned]

L1,L2=30 turns, L3=80 turns, L4=120 turns
L1,L2,L3 = 18 sm, L4=18 sm
Search head – DD configuration.
Cx can be from 47 to 100 nf
Metter = center, +/- 50 uA;
Adjustment: Firstly switch meter to pos. A and with VR1 and VR2 tune it to zero. Then switch back and adjust ground balance.
From time to time meter must be switched to pos A, to check zeroing.
Disadvantages: Unstable when the temperature rise above 35oC.

[Gene L.]

Re: Simple but effective VLF detector

Does anyone have anymore information on this circuit? PCB photo,frequency, IB ?? This was posted a year ago or so. Thank- You Gene