I just invested $18 for the Newhobby ion locator circuit the other day (NH 61). The proprieter, Violin, told me as much they were a load of codswallop before I threw my money away. Made a box (has to be wood, as plastic causes static and metal will overload it), now just need to mount the speaker and switches, and design an antenna. It comes with a basic telescopic radio ariel, but after trawling the LRL website, I'm gonna try an aluminium dish (saucepan lid) hooked to pos. and neg. to the (insulated) antenna. Other experiments may be an earth wire to my hand, a coaxial copper winding loop antenna, or a square aluminium antenna made from old tv antenna tubing.
The indicator does flash and report on the speaker when I tickle the antenna wire. It has 2 as yet unknown switches and 3 as yet unknown pots.
If it detects the fridge at a foot, I'll be happy. If it can detect/discriminate black sands from ironstone at point blank, I will be ecstatic.
If it can even see gold, I'll have kittens, do a triple backflip and speak in tongues !!
Sorry my camera did just that the other day, so no pics 'til I get a new one.