Category Archives: Miscellaneous

Toggle Switch No.2

Pushing the button once will energize the relay. Pushing it a second time will de-energize the relay. Any simple momentary action push-to-make switch will do. The prototype has a single-pole relay. But you can use a multi-pole relay if it suits your application. The circuit will work at anything from 5 to 15-volts. All you need do is select a relay with a coil voltage that suits your supply.

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Repeating Timer No.8

This circuit energizes the relay repeatedly – at regular intervals. The length of the intervals depends on the setting of R4 – and the output pin to which the “Range” wire is connected. With the range wire connected to pin 3 – intervals of up to 24-hours are available. If you need longer than 24-hours – increase the value of C3.

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New CCO Metal Detector

Thomas Scarborough has designed a new embodiment of the CCO (Coil Coupled Operation) metal detector, a new genre which he invented in 2004. This is the first IC design to appear on the Internet (there is a transistor design on many websites, and IC designs were published by Elektor and EPE). It took me just eight minutes to design this — which illustrates the simplicity of the principle.

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Universal Ding-Dong

One frequently finds gongs or chimes for sale in antique shops or Eastern markets. But supposing one would want to wire these to a pushbutton at the front door to create a ding-dong doorbell? How would this be done? Or consider, for a moment, more creative possibilities. How would one e.g. cause wine-glasses or African drums to resonate when a doorbell is pressed?

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