New Project

[Prospekteur]

....its time to start a new homemade project. Im looking for an high frequency vlf detector( something about (40-70 kHz). Is there some shematic out there?

[homefire]

I was going to try a 35Khz Lobo but got side tracked.

[homefire]

The TGSL would be a good candidate for the conversion. Well Documented. PCB in Place. Basic Coil Construction documented and proven. Has Grd Balance Provisions. Don't much care about the Discrim but it's there. Tune it up to 35Khz. 48Khz like the GMT and use those coils ? Go full blown 70Khz and use the Gold Bug Coil ?

[homefire]

What would be needed ? Retune the Filtering. Faster Op Amps ? Make some pin changes on the 4024 to get down the Threshold ?

[Koala]

....its time to start a new homemade project. Im looking for an high frequency vlf detector( something about (40-70 kHz). Is there some shematic out there?

There's a few around 20khz


Original Fisher Gold Bug. Schematics are published
Lobo is fully developed on the Russian forum and highly regarded.
Quasar ARM I believe go to 20khz





Can't think of anything with a higher frequency I have seen published

[Davor]

That would do it. Opamps are good as they are. Don't forget about Tx needing optimisation for a new coil.

[Prospekteur]

Thank you very much everyone for the good and interesting replys. Im very interested in shematic of Fisher goldbug 2. @koala.....do you talk about goldbug or goldbug 2. If everyone have shematic for goldbug 2 or other high frequency gold detector.....please share it ;-) .....ive already worked on tgsl to change frequency with changeable capacitors but quit this project on my tgsl........ I want to build something New from scratch;-) Is someone interested in build an high frequency detector. I have another new tgsl board here, but i need help in tuning this board up to high frequency;-) . my Favorite project i want to build would be something like goldbug 2.

Regards Prospekteur

[Koala]

Thank you very much everyone for the good and interesting replys. Im very interested in shematic of Fisher goldbug 2. @koala.....do you talk about goldbug or goldbug 2. If everyone have shematic for goldbug 2 or other high frequency gold detector.....please share it ;-) .....ive already worked on tgsl to change frequency with changeable capacitors but quit this project on my tgsl........ I want to build something New from scratch;-) Is someone interested in build an high frequency detector. I have another new tgsl board here, but i need help in tuning this board up to high frequency;-) . my Favorite project i want to build would be something like goldbug 2.

Regards Prospekteur

only seen the original GoldBug

[homefire]

I have a GMT so I have a few coils. It would be nice to do the 70Khz. Nothing but the old Gold Bug has been published I think. If the Op Amps are fast enough and good enough S/N then all that would be needed I think is changing the Caps on the Filters. This is how far I got on the TGSL/EDU conversion to 29Khz before loosing interest.

[Prospekteur]

@ Homefire

When thats all and when i can do with this little changes as you posted above the 29khz on tgsl.....then i will do this Modifikation on my ready build tgsl ;-) . Wich coil do you prefer for the 29khz?

[homefire]

It would be Concentric.

[homefire]

My plan was to build with the cap changes section by section and make any needed corrections as I went along. Only jumping it up to 29Khz I was thinking most of it would work.

[homefire]

Not Calculated out coil yet if that's what you asked. Original Coil with Cap Changes is what I was going to Try.

[Davor]

You missed the phasing capacitors. C9 is especially critical because it has a potential to drive U101b to saturation.

[homefire]

LOL ! That is why we have people like You. Thank You.