Electrician Tool – Continuity Tester

I had gone to buy some long wires at a electrician shop, when a terminal box had to be tested, he used a continuity tester.

Continuity Tester

When i used to buy electrical parts in the past, they used a tester box, made of wood. This had a bulb and a tubelight starter and two long wires (230v AC). The Continuity tester would light up a 40w lamp. Now he had a LED based one, so i got one for myself.

All it had, was two small cells in a plastic box with a LED, i was just flashing the LED as it looked nice thru the transparent box, it failed. The LED had burnt, the battery used. This product was not for monkeying around.

Now i performed a tiny design upgrade, I used a extra-bright 3mm Red LED with a 47 ohm resistor. Now it is robust, at least for continuity. The battery life can be good only if you make quick checks.

Improvements –

More protection may be needed to avoid damage to LED when this tester is applied across a battery by mistake. LED can flash to save battery power, one SMD – LM339 can be used for flashing and a more efficient short-leakage detector. A small oscillator with a neon may be more efficient and bright. This can also double up as a hidden Live wire or Mains AC detector.

Continuity Tester Circuit

A single chip metal detector with a range of a few inches. This is useful for detecting nails or screws in walls and floors, or for locating buried mains cable.

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