Dim bulb tester

[TC Chris]

We all want to plug in our latest acquisition right away to see if it makes music, right? Now, I've been lucky, but it's not the best way to proceed. The real danger is shorted-out filter capacitors or some other major power-supply failure. With transformer-powered radios, a cheap capacitor can burn up a very expensive power transformer.

So what to do? It's easy. Make a dim-bulb tester. It's nothing but a 100-watt light bulb in series with the Device Under Test. You need a cord, a bulb socket, and a regular AC outlet. Remember, the bulb goes in series with the device. That means it limits the current that can flow, and better still, what the bulb does tells you what's going on with your new device.

Plug the device into the dim bulb tester and turn it on. The bulb may go bright very briefly as the capacitors in the device charge up but then it should go dim. If it stays bright, there is a short circuit. Stop the test! If it goes dim, you'll get sound if the device is working; maybe not if it has other problems. But at least you're not burning up expensive parts.

Cheapest way to make one? Buy a hardware-store extension cord for a couple bucks and a bulb socket. Cut one wire of the cord and put the socket in series. You can get fancier and use sturdy wall outlets and a switch in junction boxes and a ceramic bulb holder. But this is a basic and necessary tester to have.

Chris Campbell

[William]

Good advice Chris, and a good simple way to build a "dim bulb test" that could save one lots of time, frustration, and money.

Bill

[Firedome]

There's Chinese made variacs out there nowadays that are pretty inexpensive the would be a good way to power up old electronics but not sure how the quality is.

[electra225]

Let's please try to respect this as a non-discussion board. I'd like this to be a resource for "first timers" where we give our suggestions that they can check out and come to their own conclusions. We can talk about electronic test equipment on the appropriate board. Thank you.