Delayed Car Door Alarm

Opening car’s door is very simple activity, and off course it’s just a daily activity which require no special skill. Almost nothing can go wrong, but forgetting to close the door when we doing or thinking on many tasks is a common thing. This can lead to many consequences, from as simple as air conditioner inefficiency to as dangerous as […]

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Burglar Alarm Works for Both N.O and N.C Contacts

Unlike other alarm circuit that provide normally-open only or normally-closed only configuration, this alarm circuit work for both configurations. The mechanism of this alarm circuit is very simple, that the output will be active (Q1 transistor will be conducting) if IC1 or IC2 “high”. If R2 is open, then IC1 output will be high since the non-inverting input voltage will […]

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Dual Tone Single IC Siren

This circuit is a double tone Police sound and Single tone old ambulance sound. This circuit is usually installed on a on battery powered cars, motorcycles, and bicycles for fun kid not only that, this circuit also used in  models and other games. The oscillation of IC1A and IC1B gates produces the typical dual tone sound of Fire-brigade  or Police […]

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Bug Zapper

This circuit is used to exterminate bugs. This circuit needs high voltage but low current to do that. To attract the flying bugs this circuit use lamp. But be careful, these device exterminate all bugs, although that are useful and friendly bugs. This circuit uses the principle of voltage quadruple which supplies a direct current output voltage which is four […]

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