Tube Amps / Music Electronics
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|6/25/2003 5:42 PM|
I have a few little transformers without the copper wire, just the laminations. I need to wind some wire on one trannie to get a transducer with an impedance of 8 ohms. And another one with an impedance of 2250 ohms. I need them for the spring reverb.
Anyone have an idea how to figure out what length and gauge of wire to use in order to get those impedances??
|6/25/2003 6:44 PM|
Ask the guys on the pickup forum. (You might want to measure the winding area before you pose the question) But basically, there is a known resistance-per-foot or meter for the particular guage or wire. Calculate exactly how much wire each wrap requires. That gives you your DC resistance. AC impedance is beyond me.
|6/25/2003 7:34 PM|
Hm, It would be easy to figure out the DC resistance, I could simply measure it with a multimeter as I wind it.
First I thought that, in a pickup or a transformer, the DC resistance is the same thing as impedance. Then a friend of mine told me that the DC resistance of a pickup is NOT the same thing as it's impedance.
So, what's the deal with that? Yes or no?
|6/27/2003 6:36 PM|
DC resistance is simply the resistance per wind of wire times the number of winds.
Impedance takes into account the AC resistance; in this case due to the inductive properties of the coil and its core. The coil will generate a current in the opposite direction to an AC current that is applied to it. This opposing current impedes the AC signal. The AC impedance of a coil (in ohms) is the DC resistance plus the frequency of the signal (in Hertz) times inductance of the coil (in Henries) times 2pi.
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