Dark sensor on breadboard

The circuit is ready for testing. Connect battery terminals and see the output. As you block light falling on LDR(Light dependent resistor), the LED glows.

OUTPUT:

[youtube]http://www.youtube.com/watch?v=qmWAgoHwy3w[/youtube]

THIS CIRCUIT IS EXTREMELY SENSITIVE TO DARKNESS. EXPERIMENT THE CIRCUIT IN A HIGHLY ILLUMINATED ROOM.

LED GLOWS EVEN IN LESS DARKNESS. Use torch light if the LED glows in less darkness. You can adjust the sensitivity of the circuit using a variable resistor in place of R3-300Ohm. Try this circuit with other resistances as well, for example, 1K, 10K and 100K, etc.

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Experiments with LM358

Description: LM358 is also one of the types of operational amplifier. LM358 consists of two independent, high-gain, frequency-compensated operational amplifiers designed to operate from a single supply over a wide range of voltages. This module can also be used for testing an LDR, a phototransistor and a photodiode. You just need to replace an LDR with…

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Object counter using LDR and calculator

To make an object counter we can use a simple dark detector circuit and a normal calculator. Pole and NO (Normally Open) terminals of a relay have to be connected to the two pins which are used to activate ‘=’ key of calculator.
As we block the light falling on LDR, the calculator starts counting.
For the calculator to work as a counter, we first need to press ‘1’ and ‘+’ keys.

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