AC outlet tester

2005 September 11
category: Electronics
by Rob

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.

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11 Comments leave one →
2005 September 11
Melissa permalink

man, you are smart! I don’t even know what you need an outlet tester for!

hmm…after some analysis–is it for testing outlets?

Couldn’t you just take a lamp or an alarm clock around to each outlet and plug it in to see if it works?

2005 September 11
Rob permalink

Lol! The female mind constantly… surprises me. Just when I think something is self-evident… very good question. Yes, it’s to test outlets. Especially when you just move into a new place and there’s like 3 switches that don’t seem to turn anything on.

The alarm clock/lamp approach would work, true, but they are unwieldy. :)

2005 September 12
Jules permalink

Unwieldy????

2005 September 12
Rob permalink

“Difficult to carry or manage because of size, shape, weight, or complexity” (so says Dictionary.com)

:)

2005 September 12
Jules permalink

I guess I could’ve looked it up myself!

2005 September 12
Ciera permalink

Very cool. I would so totally hurt myself if I were to try that though…I’d be safer toting around the alarm clock!

2005 September 13
Jesse permalink

So…what do the resistors and LED cost if you don’t have them? I’m guessing it’s a “free” $10 outlet tester…or something like that.

Hope you’re doing well up there my friend!

2005 September 13
Evie permalink

:roll: What a great idea. I guess I would have to go with the other females in the room, I would have just carried around something and plugged it in. Wish I knew how to do stuff like that.

Miss you and hope all is going great!

2005 September 13
Rob permalink

Ahh, very good point, Jesse. :D Same could go for the soldering iron, solder, shrink tube, and solder sucker (when you mess up!). That brings the price up to, oh… about $150?

In that case, Evie’s, Melissa’s, and Ciera’s methods are much cheaper. ;)

2005 September 16
Sarah permalink

Funny stuff! I was interested in the whole method until you rang up the grand total…

2005 September 25
icerabbit permalink

Very sweet.

As I already bought a circuit alert pen & receptacle analyzer (open & reversed wiring & what not) and have some lamps :P I’ll stick to those ;)

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