How to use a rechargeable battery in a circuit?

I want to use a rechargeable battery in a circuit, but I'm having trouble understanding it. Let's say I want two switches... One to use an alkaline to charge a rechargeable battery, and another to power an LED using that charged battery... can some draw the absolute SIMPLEST way to do that using a AA battery and this battery:

(The LED works fine with 3.6V)

Remember, I'm very dumb, don't assume I know ANYTHING!


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perkinsb1024 (author) 10 years ago
Ok, well... right now I'm working on capacitors... I have a 25V 120uF capacitor that I'm trying to charge with two AA batteries... no matter how long I let it charge though, it never gets any much voltage, it won't even blow out a 3V LED which leads me to believe that it's only putting out as much as I put in... but I thought the whole purpose of capacitors was to build up lots of energy... what am I doing wrong? (I just have 2 AA attached directly to it...)
Have you looked at my instructable?

Capacitor LED circuit

Try the equations I give using your capacitor values to see how much energy you are storing.

Depending on what type of AA's you are using (alkaline, NiMH, Li-ion etc) you may not have enough voltage to meet the forward voltage of the LED. Does the LED light if you connect it directly to the batteries?
perkinsb1024 (author)  trialex10 years ago
Yes the LED lights, but that's not the point... the capactior should blow the LED away... it's 330V... you use a 5(.5)V capacitor with 5V USB, so that's not quite what I'm after... I need to know how to recharge my disposable camera capacitor... How do I do that?
If you'd have asked this question at the start, you would have got the right info sraight away! The circuitry between the battery and the capacitor steps up the voltage. That's why the capacitor on the camera flash is rated at 350V or higher.
perkinsb1024 (author)  trialex10 years ago
Uhh... what? I have a 330V capacitor, but it never chargers to that much, I can only get exactly what I put in... Let's put it this way, I have a 330V capacitor, two AA batteries, and some wire, and nothing else and let's pretend I want a massive shock. How do I do it with only what I have?
You don't. You need a circuit to raise the voltage. If you didn't need anything else, why would the camera have the extra circuit?
perkinsb1024 (author)  trialex10 years ago
To do all the other... camera stuff? Ok, I'm going to Radioshack tomorrow. NOW what do I need? Transistors? How many and what kind? Resistors? What? Thanks
capacitors only charge up to the voltage you apply to the; in your case 3V from the two batteries. The voltage on the cap is the MAXIMUM voltage that you can apply to the cap without breaking it. You need something like the circuit from a flash (which involves transistors and transformers) to charge a cap to 300+V from two AA cells.
perkinsb1024 (author)  westfw10 years ago
That's what I figures, what's the best way to find on of those (I mean to make it... I don't want to use one pre-made from a camera) Thanks!
Start by reading Sam's Strobe FAQ, since what you're looking for is the "inverter" circuit used in most electronic flashes and strobes.

How do you feel about taking apart a camera strobe and re-assembling the components to better fit your needs?
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