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Response time of an LDR

A project log for SEELablet : Instrument Cluster For Laboratories

Minimal, yet powerful combination of control and measurement tools integrated with an SBC running Python based UIs for science & Engg. Expts

JithinJithin 07/12/2016 at 08:420 Comments

Light dependent resistors are known to be slow to respond. We'll find out just how slow they are by using an LED connected to a square wave, and measuring the resistance of the LDR using the scope.

Response to an LED driven by a 47Hz square wave. The resistance is measured by connecting the LDR, and a 5K1 resistor in series between 3.3V and Ground. By monitoring the midpoint of the two, and using the known values of either ends(3.3 , 0 ) as well as 1 resistor(5K1), one can calculate the resistance of the LDR.

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