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previous: Huey Jackson I had the same idea about a year ag... -- 1/23/2004 9:08 PM View Thread

Re: active PU

1/26/2004 2:11 AM
Re: active PU
I do have some knowleges on that subject cause I'm actualy studying electronics and I have electromagnetics leson for that (but it's so theorique i'll need to work a little to aply this to anything real :c) )  
so for the "transformer effect" yes it will do, in the receiving coil (the one for normal PU) you will see the signal who feed the electromagnet but if this signal is a high frequancie (let's say aboud 200KHz) it would be very easy to filter it out as on electric guitar you have nearly nothing higher than 5KHz (and human can't hear higher than 20KHz) so not a problem for tone  
but it could be a probleme if the intencitie of the inducted signal is too high for the wire used (in that case the coil will heat and maybe burn...)  
we know that in a transformer the curent's and the voltage's ratio is the same as the number of turn ration, so if we use the same wire and put the same numbre of turn in each coil (PU's one and electromagnet's one) you will have at most the same voltage and the same curent, so if the first one don't burn the second one will not...  
aboud the magnetic strongness, it will depend on the curent that feed the electromagnet's coil so very easy to adjuste (we could even have a buton on the top of the guitar to control if)  
to determine this curent you can do the math(i think I will, don't know when but one day...) or you can just try (use a signal generator and a power amp and see what voltage is required to get the same magnet effect than your favorit magnet) maybe 9V is suficient but I personaly dislike 9V battery because of their very low capacitie (at most 200mA/H)  
anyway we'll have to enclose the wole PU in a magnetic shild to prevent agains magnetics radiation (I think this would be suficient to disarrange some clocks)  
so if you try some thing just let me know and I will do the same...