Tags Posts tagged with "Dark sensor"

Dark sensor

A multivibrator is an electronic circuit used to implement a variety of simple two-state systems such as light emitting diodes, timers and flip-flops.

Remote tester circuit also resembles the logic of a "dark sensor (using BC557)”. LDR has been replaced with IR sensor TSOP 1738. The circuit works as a remote tester. Pressing a remote control switch near the IR sensor, switches on the LED D2.

A Voltage divider consists of two resistances R1 and R2 connected in series across a supply Voltage Vs. The supply Voltage is divided up between the two resistances to give an output Voltage Vo which is the Voltage across R2. This depends on the value of R2 relative to R1: If R2 is much smaller than R1, Vo is small (low, almost 0V) (because most of the Voltage is across R1) If R2 is about the same as R1, Vo is about half Vs (because the Voltage is shared about equally between R1 and R2) If R2 is much larger than R1, Vo is large (high, almost Vs) (because most of the Voltage is across R2)

We can see how can we make heat sensor from dark sensor.

A breadboard is a device for testing temporary electronics projects. Components used to test a circuit can be reused for other projects. None of the components are damaged. Almost all people start to learn electronics using breadboard because it is the simplest way of making circuit. The photograph shows a typical small breadboard which is suitable for beginners building simple circuits with one or two ICs (chips).

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.

Automatic Light detector using variable resistor A light detector senses light. As the light level increases and LDR meets the lowest threshold resistance, the circuit automatically turns on the LED D1. We can adjust the sensitivity using the preset VR1-10K. LESS RESISTANCE(VR1)-> LESS DARKNESS TO SWITCH OFF THE LED HIGH RESISTANCE(VR1)-> MORE DARKNESS TO SWITCH OFF THE LED