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Lets say I have an amplifier with an unknown output transformer. The OT has 3 secondary leads (which a DC resistance test determines are all taps of the same secondary winding).
The common tap and one other lead are connected to an output labeled 8Ω. The 3rd is unconnected and floating Wait... I just figured it out! I think
What I'm trying to find out is the impedance of the unlabeled, unconnected tap. Since the voltage ratio is equal to the square of the impedance ratio, I should be able to calculate the impedance of the unknown tap by running a static AC voltage through the primary, measuring the RMS voltage(V1) at the known output impedance, and measuring the RMS voltage(V2) at the unknown impedance.
I connect the output of the known impedance to the appropriate load (8Ω in our example). I run a clean sine wave into the front end, or into the PI. Thee input amplitude is arbitrary; it's just to provide a clean voltage measurement at the 8Ω secondary. Then I measure the RMS voltage at the 8Ω output, which reads 15VRMS. Then I measure the voltage at the unknown tap, which reads 10.6
Zu(unknown) = Zk(known) / (V1/V2)2 = Zk(8Ω) / (15/10.6)2 = 8Ω / 2 = 4Ω
That's correct, right??
Okay, this may be obvious and incredibly simple for many of you. But keep in mind, I'm a recovering art student
The common tap and one other lead are connected to an output labeled 8Ω. The 3rd is unconnected and floating Wait... I just figured it out! I think
What I'm trying to find out is the impedance of the unlabeled, unconnected tap. Since the voltage ratio is equal to the square of the impedance ratio, I should be able to calculate the impedance of the unknown tap by running a static AC voltage through the primary, measuring the RMS voltage(V1) at the known output impedance, and measuring the RMS voltage(V2) at the unknown impedance.
I connect the output of the known impedance to the appropriate load (8Ω in our example). I run a clean sine wave into the front end, or into the PI. Thee input amplitude is arbitrary; it's just to provide a clean voltage measurement at the 8Ω secondary. Then I measure the RMS voltage at the 8Ω output, which reads 15VRMS. Then I measure the voltage at the unknown tap, which reads 10.6
Zu(unknown) = Zk(known) / (V1/V2)2 = Zk(8Ω) / (15/10.6)2 = 8Ω / 2 = 4Ω
That's correct, right??
Okay, this may be obvious and incredibly simple for many of you. But keep in mind, I'm a recovering art student
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