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Hi guys.I have a few little...


 
6/25/2003 5:42 PM
Igor
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Hi guys.I have a few little...
Hi guys.  
 
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??  
 
Please help!  
 
Igor
 
6/25/2003 6:44 PM
Skreddy
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Re:
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
Igor
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?  
 
Igor
 
6/27/2003 6:36 PM
Skreddy
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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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