Auto-Pulse 1 coil

[Geophys]

Hi

I have used an Auto-Pulse 1 since 1976 and I would like to know if it is possible to add a coil of say 1m diameter (homebrew) in order to locate a buried aircraft at maybe 1m + depth. Will the circuit drive a large coil? Is it possible to get hold of a circuit diagram?

Many thanks

Geophys

 

[!-Rob-!]

The detector would work OK with a bigger Coil you just need to get the amount of wire turns right
I have a damaged 6" coil thats got 24 turns in it so if it was bigger you need less turns
Rob..

 

[Geophys]

Rob

Thanks for the info - that's useful to know how much wire was in the original coil (mine is still intact after 33 years!). I have seen large coils of about 1m square for use with other designs, they seem to be in the order of about 10 turns so I guess that may be a good starting point.

Cheers
Geophys

 

[Eric Foster]

Hi Geophys,

The only problem with a big coil is that the Autopulse did not have any earth's field cancelling circuit. Movement of a large coil with cause false signals to some degree. Coil inductance is 200uH. May as well give it a try. By the way, the original coils were unshielded. A shielded one would be better.

Eric.

 

[Geophys]

Hi Eric

Thanks for the info - I think I may see if the original 6" coil gives any response as the aircraft should be just under the ploughsoil and obviously consist of a large compacted lump of aluminium so we might get some response anyway. When I read further into this forum, I see that simply increasing coil diameter may not actually give much improvement particularly with low power detectors. We have successfully located steel water pipes below ploughsoil with the 6" coil so it might work without any modification although it would be interesting to see what happens with a large coil.

Many thanks
Geophys