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Depth modification of detector circuit boards.


New member
I was told that MDs are radio transmitters so are restricted to stop the frequencies getting out too far. This would definitely restrict depth.

I know a slow swing speed is an easy thing to do to improve depth.

On vintage detectors you can get onto the PCB and potentially modify them.
I remember the Fisher 1266 having PCBs with accessible components.

Any RF Engineers out there tried improving depth? Or can advise where to start?

Maybe its as easy as using a higher voltage to the circuit( I know this will drastically reduce the life of some components).

Perhaps it will be inductance to change or both resistance and inductance. When I get one it maybe it uses PWM and I can look there :)
There are plenty of MD’s out there that already get plenty of depth. It’s getting beyond the garbage in the ground too get the goodies that’s the issue. Who wants to spend their life digging deep holes when there is plenty of stuff to be found but is masked by trash. Something that can do that effectively is the answer.
The most profound topic on this I have read was written in the March issue in 2000 by Tom Dankowski titled Beneath the Mask written in Western & Eastern Treasures magazine.
Check it out before you change the guts of any machine and get yourself in Dutch with the FCC.
Wow, what an interesting read that was.
Thankyou for this informative reply.

For anyone interested in my thinking process on my first post..

I am in the UK, in Suffolk. There are fields around the Sizewell power station that are baron of anything including Iron. Very unusual in the UK.

The article has made me think a PI detector may get me past the top soil.

With new Sizewell building works, dozens of archaeologists over hundreds of top soil scraped acres are finding lots of early human activity.18 inches and deeper. Along with activity from later long- gone early industry judging by some of the dig sites.

Local Celtic gold finds suggest there was wealth here. Saxon boat burials and viking raids all around.

I enjoy speculative detecting, just me and the bewildered wildlife!

Back to Lidar and maps etc....
Think of a target as a bell. The soil as the atmosphere. The detector transmitter as the bell striker, and the receiver as your ear.
No matter how hard you strike the bell, the sound is only going to travel so far depending on atmospheric conditions and size of the bell.
The larger the bell (target size), the further from the source you can hear it.

You can have the most powerful transmitter on a detector, but the target will only retransmit the signal so far (depending on target size and soil conditions).
You can increase the sensitivity of the receiver, but that will amplify all noise. That makes it like trying to single out a single conversation in a crowded room full of people talking with loud music playing.
That is the limitation with the current tech.
Just as the CB'ers did in the past to exceed FCC rules and as Ham Radio Operators still do you could build an amplifier to place between the coil (antenna) and transmitter (detector circuit) to increase the output of a detector. Of course you can also increase your depth of detection by using the common known things; keep your coil to the soil, use lower frequency (mono), detect when the soil is moist/wet, GB, adjust detector settings.