BFO Pinpointer

[BKY1337]

Hello, i'm looking for an easy to build BFO circuit for a little Pinpointer.
I have already built one with two coils. But i saw that there are easier circuits with just one rod style coil.
9V if possible and without ICs.

[Funfinder]

look here:
http://www.geotech1.com/forums/showt...matics-Website

[homefire]

Try this one. LOW Parts and Fine for Probe. Pretty much any Quad Nand Gate IC will work. You could even just use 4069 inverter .

[BKY1337]

I need to check my stock, i have a lot of 741 ics and a lot of 4XXX to, but the 4069 is not 8 Pin so i think i dont have it.
Thanks, looks very good and easy. My BFO from easytreasure was built without ICs only 2N2222A Transistors.

[homefire]

4001,4011,4019,4069,4071,4081,7401,7402,7403 with the 74xx your limited to 5vdc but will do the same. The IC will run with less drift I would think. Both Osc are in same package.

[BKY1337]

Ok thanks, i think i have the 4011.

[homefire]

Figure out the Inductance of the coil they mention and just buy a off the shelf inductor to use in a pin pointer.

[BKY1337]

I dont know this things , i can make the coil like i want i my bfo. I have already thought about
using two fixed coils and a trimmer capacitor to adjust the frequenzy but i dont know if this is possible.

But my board is too big for a pinpointer, i think its better to make a new one. It works when both oscillators running with the same frequenzy
one needs to be a adjustable. Do you think this works with a trimmer capacitor? I just have a green one.

[BKY1337]

I just saw what a inductor is , very good. Do you think i can use one coil and one inductor with the same inductance and a potentiometer?

[homefire]

Yes you can use a switch to switch between one or the other.

[BKY1337]

I dont mean a switch. I have one coil (search coil) which runs at 104 kHz and i need another coil for the BFO which is adjustable from about 102-106 kHz
to adjust the sensitivity.

[homefire]

Why do you want the coil adjustable ? No Need. The Reference Osc is adjustable.

[homefire]

Going to make one to play with. Going to zip one on Strip Board.

[BKY1337]

I mean the reference coil and i want to remove it because its wound on a glue stick and its very huge.

[BKY1337]

It doesnt matter because i found 4 x HCF 4001BE , i have also one 4011 and 2x 4093.
Should i mix them or is 4x 4001BE ok?