Hammer Head with 3 foot coil

[Rob in KS]

Rajesh
I changed the capacitor in the oscillator circuit instead of the resistors because I wanted a slower pulse rate. With 270K at R3, you won't get a very fast pulse rate. Here is how mine did. Changed C8 to .047uf

Freq 400-1818 Hz
Pulse 55-400 uS


With my larger coil, I had to use a lower pulse rate so the MOSFET wouldn't get too hot. I couldn't run it lower than 400Hz or the 5V supplies couldn't keep up. I've hit the lower limit of the pulse rate. Having the pulse rate driving the power supplies does have it's drawbacks.

I have thought that there had to be some power supply module that would work. I haven't researched it though. I'll bet somebody makes one that would have a wider input voltage range. That way you could use off the shelf batteries such as cordless drill battery pack.

I tried to use drill batteries (14V) but it made the circuit unstable.
Sorry I can't be of more help
Rob

[rajesh]

Hello Rob,

How many turns you have put in your 3 foot coil and which wire you have used means what is awg of wire?
And what is the fixed value of R1, R2, R3, R4 you have put?

[Rob in KS]

Those resistors are just as on the schematic
R1=56K
R2=100K
R3=10K
R4=1.5K

I wasn't very scientific on my coils. I used wire that I had laying around. My latest coil uses an old RS-232 serial cable. It had about 15 wires in it. I left it in its outer jacket. I cut the cable to the size of the coil support and then soldered the wires to make it a coil. I started with 12 turns, but I lowered it to 11. The wire was 12 or 14 AWG and had a polyethylene coating. The damping resistor is about 700 ohm and the coil is 446 uH. This coil is about 39" or about a meter.

Air tests show a 12" (30cm) cast iron dutch oven at 5 feet(1.5m)

[rajesh]

hh

thank you very much for reply i changed the C8 dear rob actually im planing to builta very high sensetive and powerfull pi without dicse mode................

[Agraz]

Hello Nelson:

You use PI for search meteorite (meteoritos) ? I build Hamerhead PI project in 2003, and I see two meteorites in some times, very near...,
but I dont use PI, only simple vlf, Is best use PI for this?

[apocalypto]

what about coil for delta pulse/snifer X71

[apocalypto]

what about coil for delta pulse/snifer X71

what about coil for delta pulse/snifer X71

[mesy64]

Greetings to all friends
What is Depth detector for detecting large metal loop 1 *1 ?
The sensitivity of this metal to metal copper and gold is how much?

[Krzychu_]

Hello Nelson:

You use PI for search meteorite (meteoritos) ? I build Hamerhead PI project in 2003, and I see two meteorites in some times, very near...,
but I dont use PI, only simple vlf, Is best use PI for this?

Hello!

"Simple vlf" - If it's not a secret, can you reveal any details?

Regards,

Kris