Sent by: Olin Lathrop >> Unfortunately, even at 100w, an 8:1 transformer only gets >> you up to 28v. You'd need 1250w @ 8 ohms to get to 100v with an 8:1 >> transformer! > >Assuming a prefect transformer for now, an 8:1 transformer in this context >will step up the voltage by a factor of 8. If 100V is desired at the >output, then 100/8 = 12.5V has to go into the transformer. Another way to >look at it is that the transformer changes volts and amps, but passes power >thru. In other words, to get 20W out you need to put 20W in. Since the >impedance has already been adjusted to appear as 8 ohms at the input, you >need an audio amp that can put out 20W into 8 ohms, which is readily >available. All correct. My problem is that I was using the incorrect Ohm's Law formula I nit-picked about! Stupid me: I was figuring out how much power an amp would have to put out to generate 12.5_A_ @ 8 ohms, not 12.5v! Yes, a 20w amplifier will work fine (ignoring efficency). >Of course a real transformer will dissipate some of the power, so you will >need to drive it with a bit more than 20W in. If you can find one rated for >audio frequencies then it shouldn't be too bad. A transformer intended for >60Hz power may not work very well at 10KHz. You'll have to experiment. Yes, this is also a bit of an obstacle, but one that can be tackled by supplying more power. You'll have to think about cooling the transformer: I don't know how hot it'll get. It too, though, is an area that needs caution. Tim Massey -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body