How do you increase the amps from a joule thief?

          I'm working on a project using the joule thief circuit and when I put multiple LEDs in parallel they all get really dim. Is there anyway I can increase the amps going to the LEDs so they can all shine brightly?                                                                                                                                                                                       I was thinking a more powerful transistor or a larger transformer toroid with more windings. Any suggestions?                                                                                                                                                                                                                                                                                                                                        Here is a link to the circuit diagram:                                                                                                                                                                                                                                                                                                                                                                                  Thanks!

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Re-design7 years ago
You're pulling power out of a "dead" battery. Anything you do to pull more power may just make it quit working since the battery can't put out much power. But you might be able to make the circuit more efficient by using a better toroid or wire. If you can't do the math then you'll have to just experiment and see if you can make it better.
+lots. Fed up of seeing this question. Its bordering on attempting perpetual motion.
so...can I make a joule thief work without the battery? :) (/satire)
Yes, we can stick dissimilar metal spikes....somewhere dark and inhospitable....
I can't find any toroids. Can I use a plastic ring I have instead?
best reply evar. win. one free internets too.
transistorguy (author)  Re-design7 years ago
I was thinking of using multiple dead batteries in parallel as to be able to draw enough current from them... Instead of putting them in parallel, do you think it would work to put the batteries in series and the LEDs in series as well? This way they would still draw the same current, but just require a higher voltage....
use a resistor for each led 20ma each.
make sure that the your toroid is well winded.
transister won't matter unles you want more thant 15-20leds.

take care

robwasab4 years ago
In my experimentation with the jt, the jt works bc the inductor, once its current shuts off - from the transistor, starts creating a voltage to keep the current through it. With the led in the way, the inductor sees a open, voltage will keep rising bc no current is flowing through it. Once voltage his risen above the led forward voltage, current flows and voltage stops rising - the led allows current to flow. Now, the actual current is small so parallel isn't a good choice because each led has to have its own individual current to function properly. and the jt doesn't do current, it does high voltage. With leds in series, the forward voltage increases to say 9 volts. the inductor will reach 9 volts for a split millisecond, enough to send current through it, bright enough to light all the leds, and its the same current as lighting one led because its series. The jt is good for jumping the gap interms of voltage. Thats why you can create sparks bc an inductor will increase its voltage to keep current flowing, and you can get it so that it can get current to flow through an open - with the right set up.
lemonie7 years ago

More power-in for a start.