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previous: Tobias Karlsson Mr R.G said;....Feeding a c... -- 8/28/1999 7:57 PM

Re: Wah inductor source

8/29/1999 4:27 AM
R.G.	Re: Wah inductor source Not too hard. You rig up one end of the secondary to +9, the other to the collector of an NPN transistor. The emitter of the transistor goes through a resistor to ground. The base of the transistor connects to the base AND collector of a second NPN transistor with the same size resistor to ground. The collector/bases are fed a current through a pot. This is a basic current mirror, so a current equal to the current fed into the control transistor is pulled through the slave transistor and the winding. You could also use an N-channel JFET with a variable resistor from gate to source, gate grounded, and winding connected to the drain. Not as flexible, but simpler. You have to use a current to drive the secondary; a voltage will clamp the signal on the primary by transformer action.

8/29/1999 4:27 AM

R.G.

Re: Wah inductor source

Not too hard. You rig up one end of the secondary to +9, the other to the collector of an NPN transistor. The emitter of the transistor goes through a resistor to ground. The base of the transistor connects to the base AND collector of a second NPN transistor with the same size resistor to ground. The collector/bases are fed a current through a pot. This is a basic current mirror, so a current equal to the current fed into the control transistor is pulled through the slave transistor and the winding.

You could also use an N-channel JFET with a variable resistor from gate to source, gate grounded, and winding connected to the drain. Not as flexible, but simpler.

You have to use a current to drive the secondary; a voltage will clamp the signal on the primary by transformer action.