How to Make a Doorbell Circuit for Deaf People?

How to Make a Doorbell Circuit for Deaf People?

Doorbell for Deaf People.

When a deaf person is alone in a house, it would be very difficult to realize that someone is knocking on the door without any visual warning signal.

The main component for the Doorbell for the deaf circuit is the CMOS 4001 integrated circuit, which has four two input NOR gates

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How to Make a Current Flow Indicator?

How to Make a Current Flow Indicator?

This Electric Current Flow Indicator gives a visual indication that there is a current flow. Possible applications for this small circuit may be: a battery charger, a voltage power source, etc.

In order to achieve our objective we place 3 rectifier diodes in series, which in turn are in series with the load / battery.

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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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