# Info on voltage level triggered circuit

Discussion in 'General Electronics Chat' started by professional88, Aug 3, 2009.

1. ### professional88 Thread Starter New Member

Aug 2, 2009
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I am a communication network sepecialist. However, I need a power supply in one of my projects. This power supply should trigger on a certain voltage level and then shuts down on a certain voltage level.

My solar cell can produce 5 Volts maximum. Its very small in size and this solar cell actually charges a 0.022F capacitor (5.5V) instead of a battery. The capacitor is then expected to supply power to a sensor circuit. The sensor circuit operates on 4 to 6 volts with a current requirement of 10mA.

So, I am in need of a circuit which allows the capacitor to get charge until it reaches a certain level (say 5 volts) and then it starts supplying power to the circuit. After that it should shut down the power supply when it discharges to 3 volts.

I am using capacitor because in my case I need only 3 or 4 readings from a sensor. This does not require much power. So, before taking the reading, I will charge the capacitor by directing light on solar cell. Then the capacitor charges to a certain level before supplying power.

I would be more than thankful if you could help me in finding the exact circuit or at least tell me some sort of a kit which can do this. Some keywords for searching on google would also be appreciated. My expertise is in communication networks. So, I have very basic knowledge of electronics. Please do not mind if I ask any stupid question.

Many thanks in advance.

May 11, 2009
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3. ### professional88 Thread Starter New Member

Aug 2, 2009
2
0
Thanks for your kind response.

Actually I need to power a pressure sensor for a fuel tank. I need constant output in the range of 5V to 6V. The solar cell will first charge the capacitor but if there is no trigger circuit then the capacitor would not be able to store enough charge to supply constantly to the sensor circuit (at least for 5 seconds).

That is why I need a circuit which will allow the capacitor to get charged to a certain level (say 4V) and then turns on a DC to DC converter to give me constant output for a couple of seconds.