Joule Thief

[freepow]

@ crowclaw, This circuit works great !

Input voltage around 3.5v
When I put the switch on, the red-LED comes on (this shows the power is on for charging)
at this point we -1.5v approx for the red-LED, so we are left with about 2.0v going to the green-LED (full charge light), now I have a diode then the supercap and we have about
2.0v -.25v approx for the diode, which leave's us about 1.75v filling the cap.
The only reason I put the diode here is so when I use the cap for my joulethief, the supercap wont leak its power into the green-LED (full charge light).

Now as soon as the supercap charge rises to around 1.25v, the green-LED comes on to show the supercap is kinda full, you see the green-LED is getting 1.5v at this point because of the  -.25v for diode.
when really the supercap should be getting 1.5v and the green-LED would then light up because its getting the same,

The thing is the voltage going direct to the green-LED and to the supercap would have been
equal, which is what I want, but adding the diode before the supercap stop the supercap lighting the green-LED when I put the charge switch off.

I just want the supercap to charge up and the green-LED to come on when its full, but now I have only 1.75v charging up the cap and 2.0v going to the green-LED, I need both to be the same, and still keeping the diode where it is !

sorry for the long reply.

[crowclaw]

The thing is the voltage going direct to the green-LED and to the supercap would have been
equal, which is what I want, but adding the diode before the supercap stop the supercap lighting the green-LED when I put the charge switch off.

I just want the supercap to charge up and the green-LED to come on when its full, but now I have only 1.75v charging up the cap and 2.0v going to the green-LED, I need both to be the same, and still keeping the diode where it is !

sorry for the long reply.

That's ok I need to clarify how you are using your circuit. So your source is charging up the supercap as indicated by your red LED. When your cap reaches is fully charged point the green LED has to illuminate to show a charge condition exists...do you then remove the power source knowing that the cap is charged, as indicated by the green LED. in which case the supply current for the green LED can come from the source, I can then devise the best way to achieve the result you are after. Or do you have a preset time period to charge up the cap after which the supply source turns off and you want to rely on the green LED to indicate this state has been achieved? or may be a circuit that terminates the charge cycle when the cap is "full"

[FatBird]

Great drawing Groundloop.

[FatBird]

What software package do you use to make your drawings?

[Groundloop]

@FatBird,

Thanks for the nice words.

Well, my ratnest proto type build looks like a mess, so I prefer to post clear and
to the point circuit drawings. The software I use to make simple circuit drawings
is Windows Paint. I use Eagle CAD (form www.cadsoft.de) in more complex drawings
where I also want to make printed circuit boards.

I'm currentely running my circuit for test, charging and desulphating a 12 volt 7 ampH
gel cell battery. The battery is slowly coming back to life now.

Groundloop.