Joule Thief

[TinselKoala]

@Bill: my build of this circuit uses 2 each 1 F, 5.5 V caps in parallel with the battery, which can be switched out so that the circuit runs on the caps alone. I just installed another one for a test, so that's 3 Farads of capacity.

@xee2: It's the clipleads, then ... I knew it all along.

[lasersaber]

Three Farads!  Wow that should give you some very long run times.  Did you see this video? : http://youtu.be/SdXAjT2QPiQ   That light ran all day long and was still going after I got home from work. That was on a 1 F capacitor.  Notice that at the start of the video the voltage is at 11.02v and later at 11.03v.

[TinselKoala]

Three Farads!  Wow that should give you some very long run times.  Did you see this video? : http://youtu.be/SdXAjT2QPiQ   That light ran all day long and was still going after I got home from work. That was on a 1 F capacitor.  Notice that at the start of the video the voltage is at 11.02v and later at 11.03v.

Not so long... I am only charging them to 1.3 volts, and they are old technology caps, not like the small 10F supercaps that LTseung is using.

Energy on a cap is proportional to the square of the voltage. So you are charging your 1 F cap to 11 volts or so.... your stored energy is then
E = (1F)(11V)²/2 = a bit over 60 Joules.
In my case,
E = (3F)(1.3V)²/2 = about 2.5 Joules.

I am not working with input voltages above that supplied by a single AA or AAA alkaline battery, sometimes two depleted ones in series, and lately I am using NiMH batteries that are about 1.3 V when fully charged.

Your results are remarkable. Unfortunately I just don't have the funds to reproduce them at the scale you are doing. Keep up the good work and thanks for the ideas!

[onthecuttingedge2005]

TK, do you think a 100F double cap like this one would help with your experiments?

http://www.hifisoundconnection.com/Lanzar-VCAP10000-Vector-100-Farad-16-Volt-Hybrid-Double-Capacitor-VCAP10000

I get my main job back at the courthouse on July 1st and get a rather handsome paycheck, I can try and get one for your lab if you need it?

Jerry

[tak22]

Robin Hood and the Joule Thief, Raiding the Rubbish to Help the Poor

http://zabaleen.blogspot.de/2012/12/robin-hood-and-joule-thief-raiding.html

I was experimenting with aluminum garbage  and a solution of lye made from wood ash from the Sherpa's fire (Potassium Hydroxide, used to make soap in the old days)  to create hydrogen (a chemical reaction I knew  about and used to show my students dating from when I taught Chemistry at Marlborough High School in 1989!).  Hooking a voltmeter up to the reactants to see what was going on I observed a voltage during the reaction of between 0.5 V and 0.9 volt.  So I lowered my concentration of lye to keep the hydrogen bubbling to a minimum and hooked everything up to a Joule Thief.

The reaction was astonishing -- I was able to light the LED to full brightness, just from one coke can tab and a piece of stainless steel.  I had, in fact, created an aluminum oxide battery. And I found that I could light not just one LED from this simple procedure, but 5, all super bright!

This meant that no matter I went in the world, as long as I had some aluminum can tabs in my pocket and could gather some hardwood or fruitwood ash from a fire and had my joule thief, I could run a flashlight indefinitely, never needing to worry about batteries again!  Each aluminum can tab lasted me up to 6 or 8 hours before needing to be replaced.

tak