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Well as you know, I gave up on the concentric. In my 'Rant' post I claimed that a coil ran at 10.1KHz before potting and 7.7KHz after. This was true but not my ideas as to why. It transpires that at that exact time one of the caps on my test osc changed value so every coil I made from then on was wrong. The test osc was thrown together with cheap disc ceramics caps...DON'T. My actual detector uses monolithic ceramics.
I thought I would measure all the points in the circuit and amazingly, all are spot on so then i decided to measure the null of my unknown coil; I found out is is a Barksas Pro-Edition (about 75 American bucks, 50 quid. Hmm). The null is 40mV (at the coil not after the pre-amp!!!
If I do not make a coil then my project is not really home-made. This AM in an hour or two I made a DD that Nulls at near zero - much better range etc. When the resin has set and I do more tests I will post result.
Menawhile I am doing a postal course in Necromancy with a hope to enter Hogwarts as a mature wizard. There I will major in Concentric Magic.
I thought I would measure all the points in the circuit and amazingly, all are spot on so then i decided to measure the null of my unknown coil; I found out is is a Barksas Pro-Edition (about 75 American bucks, 50 quid. Hmm). The null is 40mV (at the coil not after the pre-amp!!!
If I do not make a coil then my project is not really home-made. This AM in an hour or two I made a DD that Nulls at near zero - much better range etc. When the resin has set and I do more tests I will post result.
Menawhile I am doing a postal course in Necromancy with a hope to enter Hogwarts as a mature wizard. There I will major in Concentric Magic.
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