Joule Thief

[Pirate88179]

Dave:

Thanks for posting this circuit.  Have you built it?  If so, what is the amp draw with a cfl or gutted led bulb?  I am still working with 1.5 v (or less) inputs but I always have an eye open for something different.  It would be great to see a video of this circuit running something if possible.

Thanks,

Bill

[crowclaw]

If you look at the primary circuit there are two transistors, think in electron flow from neg to pos, the transistors each fire a pulse into the outside of the double primary, the bemf from each turn on the gate of the other this causes the oscillation.

The transistor symbol is setup to show conventional flow but is not the way electrons move.

Basically this system is pulsing two primary's use the two primary's to step up voltage on one and current on the other.

I'll mention this again, nothing special  other than a 12 volt DC to 220 volt AC inverter. The principle of operation and circuit_ plus description is  explained here:

http://homemadecircuitsandschematics.blogspot.co.uk/2012/02/how-to-make-simplest-inverter-circuit.html

I have built many of these for various purposes over the years. The output is not quite a perfect singwave but ok for powering basic stuff. These circuits are around 70% / 75% efficient and draw a few amps from 12 volt supply.
Regards Crow

[crowclaw]

@ Dave45

With respect,
I can't understand where you get this statement from  regarding your theory of how the circuit functions?
as you quote "Basically this system is pulsing two primary's use the two primary's to step up voltage on one and current on the other."

Just a corrective technical point... these are transistors having a base connection and not a gate unlike FET devices.

[Dave45]

The circuit function is not the main issue, although it needs to pulse two primary's, the zvs might be a better option since it uses fets.

I think the wire gauges are key, we have two primary's one secondary, one primary can be used to step up voltage (large gauge wire to small gauge wire) the other primary can be used to step up amps (small gauge wire to large gauge wire)

No I have not built it, just something Im working on an idea I thought I would put out there.
Im building a system that uses a multiple coil configuration so its a little slow, or Im slow I should say  finding the right size cores is a problem so I been experimenting with iron wire, winding them like a coil, Iv had plenty of fails but I finally figured it out.

When we do find the answer I would like to build it from scratch with readily available parts and not have to depend on a special component like a ferrite core, the only problem with iron is the frequency must be kept low.

Anyway good luck to everyone on their projects
dave

[Dave45]

One of the cores, pics are not very good sorry.
I used a fast drying spray insulation between each winding, Im thinking about using fiberglass bondo to coat the whole core then spraying another coat of insulation over that.