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automatic switch

Aj_s87

Dec 15, 2012
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Is it possible to buy or build a switch that will turn on a switch automatically when it reaches 5V?
 

Harald Kapp

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Nov 17, 2011
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That was a short answer to a short question.

What exactly do you want to do? Do you want to supervise a voltage and turn on a signal when 5V is reached? Or do you want to turn on a circuit automatically if 5V are present? What is it the switch shall switch, e.g AC, DC? What power (aka current)?

Tell us your problem in detail and we may be able to find a solution - maybe even without using a switch.
 

Aj_s87

Dec 15, 2012
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It could be either, it's running of an AC dynamo which is then rectified to DC.
I have a regulator stopping it going over 5V so when reached is probably what I need.
Thanks
 

Harald Kapp

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Sorry, it is still a bit unclear.
Do you want the voltage from the generator to shut off the generator once the voltage exceeds 5V?
Or do you just want to limit the voltage to 5V?
If you measure the voltage on the AC side: do you mean 5V RMS or 5V peak?
What current do you need to switch?
 

Aj_s87

Dec 15, 2012
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Dec 15, 2012
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What it is, is I have a circuit attached to a dynamo on a push bike.
As you'd expect it takes a second or two to get up to 5V.
It needs to turn on the circuit when it gets to 5V and stay on till I stop moving
 
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