Joule Thief

[jadaro2600]

We're nearing the 10K post..amazing.  Now, I would like to make a simple request of the posters here...

I've come and gone here for a while, and have had a thought about posting circuit diagrams and the various 'individualities' regarding each - to each his own though:

Would it be possible for future posters to include the ohmic resistance of their custom wound coils, for instance, I've hacked an old DSL filter up for the inductors there and used them in a Helmholtz configuration on several of my posts - the ohmic resistance of those coils is 3.8ohms.

This resistance can usually be measured the same way that a resistor is tested; in fact, in future posts I'll be giving actual resistance of resistors and coils alike.

Hopefully this will...

Doing so would give a greater indication of the statistics of each winding - they are indeed relativistic - therefore, it may be possible for me to replicate your circuit with a different toroid if I can at least match the ohmic resistance, the chances of a successful replication or reproduction of results may increase if we document every aspect of the circuit.

[edit] ..this particular request goes out to the die-hards, as I realize that the ohmic resistance can be very low and almost negligible, it requires a persistent designer to document these things and may not fall into the realm of the hobbyist.

@jeanna,  when you say 48ohms to base, is this from + to base across coil and all?

[Pirate88179]

Its there. The Anode is on the collector. The cathode is on the emitter with the negative. I also think its a toroid problem. I may get some of the smaller ones and try those out. Ill try to lower the resistance as Xee2 suggested and see what happens with the other two toroids also.
Frank

Frank:

That yellow toroid is not ferrite it is powdered iron.  Now some folks here have been able to get them to work, but some not so much.  I think the standard, if there is a standard, is the 5 for $1, 1"OD x 1/2" ID ferrite toroids from electronic goldmine.  I have also salvaged some ferrite toroids from computer power supplies that work well too, although I have no data on the permeability of those toroids.

Thanks for posting your circuit.  I see you have already received some helpful suggestions.  You will get it going on 1.5 volts for sure.

Bill

[Pirate88179]

G'day all.

@ Bill,  nice work with the flashlight. Given there are various levels of "deadness" in your batteries how much longer do they last , on average?

Ian:

Thank you.  Most of those batteries are from my digital camera from my business and they appear to stop working and are declared "dead" at between 1.1 and 1.2 volts.  I will keep everyone posted on the longevity of this new light but I have not done a test like that yet.  We can almost roughly guess what it might be however.  The light called for 4.5 volts and I am feeding it about 6 volts or so now with the JT.  LEDs, we have found, will light on mostly volts with very little amp draw so, my guess would be at least 3 times longer but, we will see.  When I lit those 400 leds from the Fuji, that was putting out mostly volts from the single AA battery.

This modification is very easy for anyone here to replicate.  The hardest part is finding a flashlight body that has enough room for the AA battery and the 1" OD toroid.  After that, the rest is easy.  So easy, even I could do it.

Bill

[jeanna]

@jeanna,  when you say 48ohms to base, is this from + to base across coil and all?

Hi jadaro,

The pot goes from the base of the transistor to one end of the coil. (so, not across the coil but in series, if you will.)

In the past, we have agreed to call this the 'base resistor'.

I hope I didn't just make it worse!

jeanna

at the end of the pointer

[gadgetmall]

Hi pirate . Nice Mod .I see your thinking like me when i see three and 4 batteries powering an led . I wanted to let you and everyone else that you dont have to use a big torroid . I have these tiny Small little bitty ferrite beads that work just as good with  8 to 11 turns and a 1 k ,2n3904 or an Msp darlington . you can slide 5 of them on one leg of a transistor . I use # 32 wire and they can mod even the tiniest light .
ANd one more thing . I just got lots of FREE supplies from 7 different electronics companies . all the led transistors backlights light tubes and pipes torroids  ics you name it all for free .I got what should have cost over 200 bucks worth of stuff all delivered with in 2 -3 days UPS . I have a list if anyone is interested . Its too big to post here .
Take care all .
Al