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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.

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.

Electrician Tool - Continuity Tester

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.

Continuity Tester

This article describes a simple continuity tester, based on an ATtiny85 and a piezo buzzer, designed for checking circuit wiring, or tracing out the tracks on a PCB:

Electronic Fifteen LED Roulette

The following was submitted on July 11th, 2007. Message: I want to combine Ne555 with 74154 IC.The indication of the outputs must be shown with LED’s but up to so far it need 15 outputs ,is it possible the way i did? if not i will need your assistance

Mail from CY

LED running lights are used to decorate Christmas Trees, Festival Surroundings and even  Buildings. A Clock and a counter are basically required. Many LEDs can be used in parallel with driver transistors. Upto 15 count is is good enough. Many colors can be used and with a PWM or VCO you can make it Audio or Music effects lights like strobe lights.

Electronic Fifteen LED Roulette

Electronique Réalisations РRoulette

Multi-Colored LEDs and drivers and even PIC microelectronics with Visual Effects in the form of ROM tables can make Alphabets and Numbers appear in LED arrays. Some have made Mini Ocillosocpes and Toy Spectrum Analyzers too in LED DOT Matrix Arrays.
LED Sequencer Circuit

The above circuit is another variation of a basic LED sequencer circuit. Note again the use of the 555 as a clock. The 555 is likely one of the most versatile chips ever invented. The output of the 555 is coupled to a 4017 Decade Counter Divider another very widely used chip

555 and CD4017 Running Lights