How do I measure output impedance?
Reply #4 –
You need: 60 Hz sine test signal, digital multimeter, dummy load.
Measure the voltage unloaded and with dummy load.
Calculate:
Zout = (Rload * (Vnoload - Vload)) / Vload
Example:
We measure 1V unloaded, 0.9V loaded and our dummy load is 30 ohm ==> (30 * (1 - 0.9)) / 0.9 = 3.33 ohm output impedance at 60 Hz.