Earth Electrical Energy Datalogging Experiments

[sm0ky2]

Smokey:

All leds will not turn on with a single AA battery...hence the JT circuit.

Bill

even with my JT, it takes 2 batteries.... maybe i didnt make the JT "correctly"??  i followed this

http://www.instructables.com/id/Make-a-Joule-Thief/

seems to just be a joule-relay.. its not thiefing anything

[Pirate88179]

I have used a lot of super bright and ultra bright leds lately but, even the very small tiny leds I have (regular, not 10mm) need 3.5 volts and about 20 mA's to light.  Now, if you have not reversed the polarity on you JT circuit somewhere, which is very easy to do, trust me, a single AA bat. is plenty to fire even an ultrabright.

Try reversing the polarity on your led as these are diodes and will work only one way.  Did you use a 2n3904 transistor?  If not, you may have one that will not turn on with less than 2.5 volts or so and this could be the reason.  The 2n394 will work easily and so should the 3055...maybe some others too but I can't speak to them.  If you did not use the 2n3904 then I suspect your transistor requires too much juice to even operate at all.

Bill

[sm0ky2]

I have used a lot of super bright and ultra bright leds lately but, even the very small tiny leds I have (regular, not 10mm) need 3.5 volts and about 20 mA's to light.  Now, if you have not reversed the polarity on you JT circuit somewhere, which is very easy to do, trust me, a single AA bat. is plenty to fire even an ultrabright.

Try reversing the polarity on your led as these are diodes and will work only one way.  Did you use a 2n3904 transistor?  If not, you may have one that will not turn on with less than 2.5 volts or so and this could be the reason.  The 2n394 will work easily and so should the 3055...maybe some others too but I can't speak to them.  If you did not use the 2n3904 then I suspect your transistor requires too much juice to even operate at all.

Bill

i used the 3904s first, as thats what the instructions said to use, but i also gave it a go with a dozen or so others,
i tested the transistor, they're turning on, power is flowing through them, but its not enough for the LEDs...

not sure whats wrong with my JT..

i'll try re-winding the core with idencitle wire, as mine is currently using 30/32 awg from the crystal-radio kit, two different sized might be the problem.

[jeanna]

even with my JT, it takes 2 batteries.... maybe i didnt make the JT "correctly"??  i followed this

http://www.instructables.com/id/Make-a-Joule-Thief/

I had that problem with my first joule thief. I had bought a ferrite magnet from radioshack thinking it was ferrite.

The thing is if the transistor is not operating you will need the 3 volts.
So, something is wrong.
Maybe backwards, maybe wrong part, maybe the transistor was upside down when you identified the E and C.

1-Put the resistor onto the base
2- wrap the toroid with 2 different colored wires and connect the end of one to the beginning of the other. (I like the way they show this part in the Makezine video.)
3-Then you have 3 legs on the transistor (one has the resistor)
You have 3 wires on the toroid. BUT THEY DO NOT MATCH EACH OTHER.
The twisted pair of wires goes to the pos battery lead.
4-The Emitter goes to the neg battery lead.
5- Now you can match up the rest.
Resistor to one free toroid wire.
Collector to the other free toroid wire
Stick the led in to those last wires. (usually the short lead goes to the Emitter, but not always.)

Maybe one of those pieces will help. (I hope)

jeanna

i'll try re-winding the core with idencitle wire, as mine is currently using 30/32 awg from the crystal-radio kit, two different sized might be the problem.

Sometimes that kind of wire shorts out.
Do you have any tele wire cat/5, I think they call it?

[sm0ky2]

'bell wire' is what we call it..

i appreciate the concern, but im a computer engineer, i can do this blindfolded in my sleep....

wire shorting out, possibly, if it gets scratched or kinked..
i'll try with bell wire, i was using the magnet wire because i thought the insulation on the other would be too thick to activate the ferrite.

guess thats all i can do at this point is keep trying different things.