ldr engineer

Posted on Feb 7, 2014

LDR( Light dependent resistor ) Engineering is a technique of making several electronics circuits following thelogic of a simple light and dark sensor using transistors, 555 IC and 741 IC. Out of several optical sensors, light dependent resistor can beused for making light/dark sensors. A dark sensor switches on transistor or LED wheneverthe incid

ldr engineer
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ent light intensity is decreased, whereasa light sensor works in opposite way. In LDREngineering, we first understand the working principle of any circuit using LDR, and then we replace the LDRwith a fixed resistor or some other electronic component that makes the simple automatic light/dark sensor work as a completely different device. Making automatic light/dark sensor circuits using different methods can make you observe several electronics components. On the other hand, modifying those automatic light/dark sensor circuits to some functionally different circuits like touch switch, water level indicator, clap switch, etc. can make you understand about those circuits. In this article, we will see how we can use the concept of a dark sensor to make a touch and a clap switch. Light dependent resistor (LDR), also called as Cadmium Sulphide (CdS) cell or photoresistoris a resistor whose value depends upon the incident light intensity. In darkness, the resistance ofLDRbecomes high and in light, the resistance gets low. The resistance variation phenomenon of LDRhas been takenas a base for making circuits of LDR Engineering. The following circuit works as a dark sensor. If the light falling on LDRis blocked, it switches on the LED D1. It has been configuredin monostablemode of 555 timer which means that the circuit switches on the LED D1for a specific time. The switching time is determined by thecombination of resistance R1and...

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