transistor switch problems

[lamnak]

Hey Guys, I need to discharge a capacitor into a battery, but the problem is i need a switch that will allow the transistor to build to 2v dc then discharge to .6 v dc then repeat. This circuit cant use any external voltage. any ideas?

 

[Roff]

Hey Guys, I need to discharge a capacitor into a battery, but the problem is i need a switch that will allow the transistor to build to 2v dc then discharge to .6 v dc then repeat. This circuit cant use any external voltage. any ideas?

What sort of power supply (battery?) is charging the capacitor?

 

[lamnak]

hey Ron, thanks for replying, ok i have made progress with what i am trying to do, to explain to you further i am trying to take the charge from a 2.5 volt 10F capacitor and store it in a battery. I have gotten to the stage where all i need is a circuit that is normally closed, that only turns on when the capacitor reaches 2 volts and turns off when it drains to .4 to .6 volts, then repeat the process. the only power that is comming in the circuit is from the shaking of the magnet through the coils,( the flashlights that dont need batteries). Is there a switch that will be normally closed and only open for to dump the capacitor and using only a small voltage from the capacitor to do so?

 

[Roff]

What is the nominal battery voltage?

 

[lamnak]

making progress

i need the circuit to run from a 3 volt cr2032 battery, this is waht i need it to do.
1. activate a normally closed relay at 2 volts
2. deactivate when the voltage drops to .8 volts
if possible maybe some potentio meters could be added to make fine adjustments.

 

[Grossel]

A relay would be a problem when you can't get higher voltage than 2V.

The problem you describe here seem to be similar to the problem by getting a DC motor to run from a solar cell that cannot provide enough power.
This problem can be solved using a quite simple schematic:
The T3SE type 3 solar engine by 2N3906,2N3904
basic solar engine schematic

 

[lamnak]

thanks

I will build this circuit and see if it works out for my project, thanks for the help. I will post the results.

Thanks again.

 

[lamnak]

The solar cells work perfectly after slight modification, thanks to all that helped.