Single AA battery to light WHITE LED for long-long time

[amigo]

Here's my setup (for the past couple of months). I have taken several photos as I was adding more LEDs to the circuit tonight just for fun. Remember this is NOT the original setup as per OP but my modified version of the Joule Thief.

I'm adding the photos in sequence, and they are labeled as well, so it should be easy for you to follow. First one is the circuit schematics.

[zon]

@amigo

How long your "led circuit" lit on,  for drain that battery with load  one led.

May i know, how many turn bifilar coil to get oscilation between 30 Khz --- 350 Khz.

zon

[Feynman]

@amigo

Nice pictures! 

I will cannibalize a toroid asap.  Nice scope also.   Interesting wave!!!!   I don't see a SINE wave there, I see a sharp gradient! 


@zon

There is probably a formula you can use to get a rough idea of oscillation frequency.  I will post the formula if I can figure it out once I build your circuit.  You can also use a scope or frequency counter to see.  You can get good deals on these equipment on ebay sometimes. 

Thank you for the coil diameter ratio. That is a really good idea.  I purchased the closest ratio I could get (since I am in America all the measurements are different!). 

[amigo]

@ Feynman,

thanks, I believe picture is "worth thousand words" and if it helps others, even better

@ zon,

I have not really kept the circuit on for extended periods of time, I simply figured based on 12mA of current that it would last days, based on the 2300mAh battery I use. I guess I should do a real test, perhaps tomorrow night I'll keep it on and see what happens.

Below is the photo of the ferrite bead I used and the coil itself. The wire used is 30 AWG bi-filar wound to 20 turns. I might try with AWG 34 and 39 and see what happens, my guess is that the oscillating frequency would change. Right now with this coil you can see it start at 100KHz, but if you add more LEDs the frequency goes down...

[zon]

@groundloop

On my latest circuit's, after running more than 24 hours

Measurement at the led,  3mA,  2.7 VDC

at (-) battery 1.291 VDC, 13.85 mA

@amigo
I can't  figured how long it will drain, based on cureent at one point, because at certain time it will drain very slow...
It's like ridding bycycle, more power on the start but "less power" after on the road.



zon