Using rechargeable cells for a joule thief? :shock:
Another joule thief.
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12th April 2009 03:34 PM #41audioguru
A lead-acid battery powering a Joule-Thief??
Originally Posted by Hero999
Rechargeable lithium batteries also do not like being discharged too low.
But the rechargeable Ni-Cad cell in each of my solar garden lights gets almost completely discharged every night for years without any problem.
The voltage stepup circuit is similar to the Joule Thief and a few of them do have the Joule-Thief circuit.0Uncle $crooge
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12th April 2009 03:45 PM #42forumlicker007
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12th April 2009 03:48 PM #43duffy
As long as we are on the subject - you can get a 1.5V to 5V step-up switching regulator out of an "emergency cell phone charger" that runs on a penlight battery. Quite small, reasonably cheap, and surprisingly well-regulated across a range of loads.
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12th April 2009 05:58 PM Thread Starter #44Sceadwian
I only made mine to finish off all the AA's I got floating around. Yeah, Lithium's go into a 'coma' if they're discharge too low, parts of the chemistry undergo a chemical change that renders the bulk of it inert.
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12th April 2009 06:29 PM #45Hero999
It's recharging severely discharged lithiums that causes problem. Electrolysis occurs causing highly flammable lithium metal to from from the salt.
This is why most battery chargers refuse to charge flat lithums and some batteries even have a protection circuit which disconnects the cell if it becomes too discharged.0
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13th April 2009 01:51 AM #46sPuDd
Its an addiction
Couldn't help myself.
I think the ferrite transformer I used was surplus from a MOSFET gate current drive setup. I think it has about a 100:1 turns ratio. Located what looked like the heaviest winding and used that for the base drive, and the other one for the collector winding. Used a BC639 first, then changed it to a BD139.
Both worked fine, with the BC639 getting about 0.5V min, and 0.6V for the BD139. Just goes to show, any old crap will work in this setup. Just vary the base resistor for the brightness range you want.
sPuDd..
RIMG2329.JPG RIMG2330.JPG0
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13th April 2009 03:21 AM #47colin55
These devices cost $30.00 in the local shops in Australia:
As long as we are on the subject - you can get a 1.5V to 5V step-up switching regulator out of an "emergency cell phone charger" that runs on a penlight battery. Quite small, reasonably cheap, and surprisingly well-regulated across a range of loads.
Here's a simple circuit:
You can now get them on the web for less than $5.00!!!0Last edited by colin55; 13th April 2009 at 03:48 AM.
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13th April 2009 03:35 AM Thread Starter #48Sceadwian
Apparently Colin doesn't know how to comparison shop
Emergency Mobile Phone Charger Battery Nokia Moto Power - eBay (item 280331403113 end time May-07-09 09:03:29 PDT)
$4.66 with free shipping in the US.0Last edited by Sceadwian; 13th April 2009 at 03:36 AM.
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