Electronics Projects: Simple 12 Volt Day Night Switch

Posted on Feb 5, 2014

At times it`s really very annoying to see the street lights kept switched ON even during broad day light. The present circuit of an automatic night light can very effectively put an end to this problem. Read here how to build it. We all know how important it has become tosave electricityin today`s circumstance where it is getting difficult to fulf

Electronics Projects: Simple 12 Volt Day Night Switch
Click here to download the full size of the above Circuit.

ill the power requirements for our cities. Today everybody along with the politicians and the official authorities are busy putting forth their own opinions regarding the issue. But ironically at times we find the street lights kept switched on even during broad daylight, and this clearly shows how irresponsible these men can be. So instead of depending on these officials, why not take some help fromelectronicsand find a solution to get the work done automatically A simple circuit of an automatic night light described in this article can very accurately switch ON a load (street lights for example) when darkness falls and switch it OFF when dawn breaks. A single NAND gate, a PNP transistor and few other passive components are the only things needed to construct this useful gadget. The circuit description can be understood from the following explanation: An LDR (Light Dependent Resistor) which is also connected at the input of N1 is used to sense a difference in light levels. A LDR is in fact a resistor which changes its value with a change in the intensity of light falling on it. In the absence of light or when its dark, the LDR offers an infinite resistance and thus the input of N1 is kept at logic high due to the voltage received through VR1. This means that at this instant the output of N1 is logic low, the relay is activated through T1 and the lights (load) connected to the relay contacts are switched ON. With an...

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