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

[Feynman]

Okay here's my toroid!  Red white blue windings for home country 'US and A' !!

[amigo]

More photos from my latests tests; I have taken my own advice from couple of posts back where I suggested to explore why 2N2222 works better than 2N3904.

The configuration now is similar to the original Joule Thief schematic except that the LEDs are not grounded but connected to the + of the source battery like in the Bedini circuit. Left side of the photo is using 2N7000 N-FET while the right side is using 2N2222; both circuits have 7 LEDs each of the same kind (generic super bright white).
When connected to the batteries (~1.3V 2300mAh NiMH) the circuits consume about 10mA of current each (the right circuit was adjusted to consume 10mA by using two resistors in series: 4K7 and 2K to the base of the transistor). The left circuit does not have any resistors - top of the coil on the driver side is directly connected to the base.

Very important note that I have observed is that a DMM connected to measure current will skew the oscillating frequency and boost it up which is obviously inaccurate and should not be done. Have the DMM connected, measure the current, then disconnect it from the circuit and then run the circuit normally with the scope connected.

Judging by the photos, the left side is brighter than the right which shows we should do more experiments with the FET transistors...

[Feynman]

Thanks amigo, great work.

The fact that your circuit is only consuming 10mA is remarkable.  I'm sure these sorts of power supplies will be useful as emergency flashlights, as they operate using an otherwise "dead" AA battery.

Here is a picture of the output, measured at the cathode (+) of the LED, using the groundloop version (trifilar) of joule thief.  I will also attempt amigo's and zon's versions as well.  Anyway, with groundloops version and a 23.5mm toroid with 30AWG (0.2540mm) wire trifilar drilled, I am getting just under 20khz as the circuit frequency.



EDIT:  V/div = 0.2 , T/div = 10us  .. but those transient peaks are real high, anywhere from 2V - 18V depending on where in the circuit you attach the probe.

[turbo]

Yeah, I agree.  We don't know if it's OU .   But strange enough to warrent ... EXPERIMENTS!!!    

Hi

I have played with many of these types of devices a couple of years ago and as they are presented here they are not OU devices.
But they can be.
For this to be, you only need to put in a verry small spark gap and make sure the voltage is sufficient.
Im not talking about millimeters sparkgap but rather one hunderth of a millimeter.
Much like when you use two pencils and the tips are almost touching each other.
The miniature spark will imediatly push up circuit performance.
It is in the disruptive discharge.
You also need a couple more diodes of the ceramic HV model to redirect energy back into the battery/capacitor.
A combination of capacitor / neon bulb will also work verry well.
In that case it runs on bemf and the voltage produced is many times higher as the pulsing voltage.
No need to use galvanic coupling, it can be done wit a simple primary coil only.
The capacitor builds up a charge ,and this charge will keep building up untill the voltage has reached a certain value and it will discharge itself thrue the neon bulb.
Mechanical switching works best.


M.

[amigo]

Feynman,

I totally agree that these could be used as emergency lights and that is the whole idea for me to explore this because just recently we had a power transformer blow up in the neighbourhood and everyone was without electricity for several hours (late afternoon in winter, dark and cold...). Having lights that would last for hours and hours at full brightness would be a good step towards making one feel better about power outages (if there's anything good about them).

I have driven my circuits up to 100KHz but in general they operate from 50-90KHz although depending on the core I use they go down to 25-35KHz as well. There's lots more experimentation needed with different core sizes and wire gauges to find the optimal configuration between maximum brightness and minimum current.

Now if only we could somehow plug in some capacitors in there and have them replace the battery during operation so that we only use the battery to start the process...