After reaching saturation point concerning Brexit and Covid, I thought I would escape for a while and concentrate my energies on a project in the workshop.
Most members might find it as interesting as removing wax from their ear with a hairgrip, but for the odd one or two I thought it might prove interesting and different, so I’ll post my progress…or lack of…
How to Build a working Metal Detector.…Hopefully!..
Before I jump into the technical stuff I must point out that building a metal detector is not a new thing for me, I managed to build a reasonably decent BFO (Beat Frequency Oscillator) detector back in the eighties.
Again, just last year, I found a decent drawing on the net that appeared to be more sensitive that my previous version, so on and off over the last twelve months I’ve been assembling it, unfortunately after extensive testing, studying the drawing until I went blue in the face, and fault tracing I’ve been unable to find what the problem was…
This was the circuit…
A metal detector needs a search coil…The bit that skims the surface of the ground and picks up any fluctuations in either RF waves or Magnetic waves when metal is located. In most cases it is the hardest bit to construct, so before I start this kind of project, I see if I can produce a good search coil, the circuit is usually the easiest bit for me…supposedly. This was the search coil for my first attempt…I was quite proud of it…
I couldn’t help noticing all the unused holes in your circuit board, Foxy. It seems such a waste. Can’t you think of anything to stick in some of them?
They (circuit boards) might look complicated Tabby, but when you break them down into the various stages they are fairly simple to understand. Sort of ‘Bite size bits’…
Ha Ha! That’s how you buy them Harbal, they are called ‘Veroboard’ and come in various sizes, just about any circuit you can mention can be adapted to fit those boards. I find it very engrossing working out how to layout the components for best effect. Like doing a puzzle…
That sounds brilliant Besoeker, back in the early days I would scrounge parts from old tellys, radios, and all manner of electronic equipment, I now have a very extensive range of components to work with, but you can never have too many.
On certain projects though where specified parts are required, like IC’s or semiconductors, I revert to buying them. The circuit described in my project requires a MOSFET and a couple of IC’s, but I will explain about those later. Thanks for your offer Besoeker…
Electronics, I once new a Wizard who could repair anything electronic, but, his self restricted him, just for ego, (or something to occupy the mind) he repaired stuff for folks FOC. That is stupid in the rationale extreme, but was rational in context…
It is possible to purchase circuit board without the holes Harbal. The board is covered with copper on one side and you can etch the shape of your circuit using acid to burn off the unwanted bits of copper, you can then drill just the right number of holes you need…So no wasted holes…
