Charge capacitor to a small voltage

[coolrox86]

Is it possible to charge a capacitor to a small voltage of 3mV with just current 5mA in 3 seconds? The capacitor is 0.667F. I want to fully charge back the capacitor every time after it has used 3mV for sending signal via a small radio module.

Any idea and help is well appreciated. Thanks!

[stj]

Re: Charge capacitor to a small voltage

0.667f?

[kikkoman]

Re: Charge capacitor to a small voltage

wait - what?
up to 3mV? you probably mean the voltage drops by 3mV.
you know that if you connect a cap to a voltage source its resistance goes to infinity (in theory) as it approaches full charge?
this means that all you have to do is hook it up to its desired charge voltage. the cap does the rest.
that voltage drop is a pretty impractical way of measurement. plus, as I suspect that cap is a Goldcap (or similar), you might get inconsistent transmitting power since those caps only can deliver very low currents.
they also are very unforgiving towards overvoltage.

hook that transmitter up to a stable voltage source and measure the supply current as a reference (and check against the cap supply). it's much easier to work with if you know the values of your circuit.