There are a couple things a soundcard could come in handy for electricians. Dual channel oscilloscope and RCL meter/
The first circuit shows you a design for oscilloscope:
That circuit gives an impedance <500K on CH1 and CH2. R1 and R2 adjust the voltage range. R3 and R4 is for current limiting resistors for the pots and switching diodes. All diodes clip the voltage to a safe level for the soundcard. You can test the circuit by applying a voltage and see if it knocks it down to hundreds of millivolts. One direction of turning should increase the output while the other decreases. And don’t forget to check both polarities!
The RCL meter is simpler and easier. Although the software is shareware its worth a try. I talk to the daqarta team and they said after the trial expires the RCL meter won’t work. You must make resistor R1 removable, so that it can be calibrated.
Here's a calculator that will give you actual RMS or Peak-To-Peak voltage from the uncalibrated voltage.Uncalibrated Voltages(Separated by commas):
Actual Voltages(Must be in the same order as the uncalibrated ones):
Voltage to be measured:
Soundcard Scope Windows
Soundcard oscilloscope box