Joule Thief

[freepow]

@ ALL,  Can someone who knows !, if they can tell me if its OK to place a SuperCap in a circuit "on its side"
instead of standing up ?

[crowclaw]

i have seen that on other explaernations but couldent make sence of it
could you explain what limiting the current would do
what i wont to happern is when the battery hits the charged voltage i wont the supply voltage to shut off and come on again when they batterys drops below the set level

i thoght the zener would of been on the positive rail so the voltage/current build up until it reaches the overflow point if you get what i mean that then saturated the transistor that then shuts off the flow of power

Hi, The current gain of a transistor is adjusted via the bias current applied to the base junction. If you don't limit the base current, the transistor will turn 'hard on' and can cause a corresponding heavy collector current to flow... resulting in the transistor overheating and failing. The best way to achieve the type of control your after is by using a comparitor circuit. Google 'comparitor circuits' for some ideas, these circuits offer  precise control action and use Op Amp IC's... cheap and simple, plenty of circuit ideas available to play with.

[crowclaw]

@ dasimpson

I meant to mention when working with semiconductor devices at very low voltages!
You have to take into consideration the voltage drop which occurs across semiconductor junctions... typicaly 0.7v for for silicone diodes and 0.2v for schottky diodes. Same applies with transistor junctions... may not matter to much at higher circuit voltages but at low levels for charging cap's you have to take these drops into account and adjust circuit values accordingly.

[altrez]

@ ALL,  Can someone who knows !, if they can tell me if its OK to place a SuperCap in a circuit "on its side"
instead of standing up ?

Yes it is fine.

[dasimpson]

i think i will just stick to trickle charge limits lol

@ dasimpson

I meant to mention when working with semiconductor devices at very low voltages!
You have to take into consideration the voltage drop which occurs across semiconductor junctions... typicaly 0.7v for for silicone diodes and 0.2v for schottky diodes. Same applies with transistor junctions... may not matter to much at higher circuit voltages but at low levels for charging cap's you have to take these drops into account and adjust circuit values accordingly.