Light Operated Relay Circuit using LDR

Light Operated Relay Circuit using LDR

Light Operated Relay Circuit using LDR.

The LDR varies its value (ohms) depending on the amount of light that illuminates it. The more light less resistance and less light more resistance, The level of light that makes the relay activated is adjusted to the desired value with a potentiometer.

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12V Auto Turn-off Battery Charger with Current Limiter

12V Auto Turn-off Battery Charger with Current Limiter

12V Auto Turn-off Battery Charger

This 12V Auto Turn-off Battery Charger with current limiter, uses only 4 transistors, will stop charging the battery when it has 14 volts between its terminals and limits the charging current to a maximum of 2 amps.

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Car Burglar Alarm using two 555 timers

Car Burglar Alarm using two 555 timers

Car Burglar Alarm using two 555 timers

This is a simple Car Burglar Alarm circuit that uses a dual contact relay and two 555 timers, each of them working as a monostable multivibrator.

The alarm will activate the car horn, approximately 5 seconds after either door is opened and has not been properly closed.

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Delayed activation 15V voltage source using LM317

Delayed activation 15V voltage source using LM317

Delayed activation 15V voltage source using LM317.

This circuit uses the LM317 voltage regulator. This voltage source also uses a bipolar PNP transistor and an electrolytic capacitor, to achieve a delayed activation of the voltage regulator

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