Why buy a $20 AC outlet tester, when you can build one for free?
The parts necessary are:
- 1 – old AC plug. I got mine from an old power cord.
- 3 – 100K Ohm resistors in parallel. This keeps the power dissipation down so they don’t get hot.
- 1 – LED. I chose red, size T-1 3/4
- some heat shrink tubing for electrical insulation between the leads
NOTE: this circuit will not detect reverse polarity of the AC lines, or missing earth ground, etc.