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Problems with power supplies. Answered

i made a small circuit board which is a proximity sensor that turns on or off a small philips genie light(its a small white tubelight like light ).i tried powering it up with a 9v battery and it works fine and the relay on the circuit board switches the ac220v load and the light goes on ,however when i try powering it up with a 10vdc adapter the relay on the circuit board keeps clicking(here i have not used the ac load to switch the tubelight,i was just experimenting and came upon the problem) .what should i do .pls help me.
 

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Lectric Wizard (author)2013-05-10

If the above answers don't work you may be drawing too much current from the adaptor. What is the rating of your adaptor -will say xxx mA,someware on the case? Relays can sometimes draw fairly large current as they pull in.

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Josehf Murchison (author)2013-05-10

A lot of cheap adapters don’t have a cap on the rectifier so steveastrouk is probably right, I would add a single diode 1N5817 just in case there is a week diode in the adapter and as large of a 16 volt electronic cap.

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steveastrouk (author)2013-05-09

Put a good sized electrolytic capacitor across the power input to your board. 470uF should be ideal.

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Strontium (author)steveastrouk2013-05-09

does it act as an noise filter cap or as bypass cap ?can i use 100uf ?
oh and thanks for answering my question.

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steveastrouk (author)Strontium2013-05-09

Here its acting as a "reservoir" capacitor, and holding charge when the nominally DC (but probably actually only rectified AC) dips. 100uF might work, but if the relay takes too much current, it might not be enough - put another one in parallel !

Steve

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