Joule Thief

[Groundloop]

Yes, but I also had some problems with nonworking croco v´cables and contact problems...

Never work with these awfull crococables... but I now don´t find my wood plank, where I wanted to
use nails to solder it all on...

Have to go...

Hopefully Laserhacker will be still around today and will tell use the new exact circuit diagramm
with screwing it up again 2 times ! Lol !

Regards, Stefan.

Stefan,

I also is looking forward to a circuit drawing from LaserSaber.

I will test more this weekend................

GL.

[TinselKoala]

RE mosfets: they switch by charge (voltage) not base-emitter current like bipolar transistors. Most mosfets need at least 4 volts (but negligible current) on the gate to begin to turn on and 6 or more for solid turnon (logic level can switch fully with 5 volts on gate), and are easily damaged by HV (read 20 volts over the Source pin voltage) spikes to the gate. This means that they are not going to work as the primary transistor in a JT, I think. However it might be possible to use a mosfet, with a little fiddling with resistors, as the second, driven transistor in the 2-transistor designs above. I am going to have to confirm both these results experimentally, but that's what I'm thinking now.
My LED ring oscillator uses 2n7000 mosfets and sometimes acts strangely when I drive it with the JT but I haven't failed any of its mosfets yet. The 2n7000 is a great little mini-mosfet, it's the "2n2222" of the mosfet world. Since these are so cheap (about a dollar or less each) I'd suggest trying one of them first in a hybrid design, driven by the 2n2222 or 2n3904.
The body diode is a result of the manufacturing process; not all mosfet  _symbols_ show it -- most 2n7000 symbols don't-- but it's there to some degree in all mosfets I know about including the 7000.

[TinselKoala]

Yes, but I also had some problems with nonworking croco v´cables and contact problems...

Never work with these awfull crococables... but I now don´t find my wood plank, where I wanted to
use nails to solder it all on...

Have to go...

Hopefully Laserhacker will be still around today and will tell use the new exact circuit diagramm
with screwing it up again 2 times ! Lol !

Regards, Stefan.

Or use them as little as possible. They really are terrible. The ones you get cheaply at discount stores hardly have any copper wire in them at all, just thick insulation with a tiny bit of actual wire. The clips are crimped to the wire and it's easy to break the crimps, get partial or intermittent connections. I always take them apart and solder the wires to the clips, and do spend the money to get the ones with "real wire" instead of the tiny cheap stuff!

It is also very easy to make wiring mistakes, to get effects due to impossible-to-reproduce stray inductances, and to create really dangerous situations if you work with really really high voltages, as I do. I am always "shocked" when I see someone demonstrating, say, a flyback driver at 20 kV using clipleads. What are you gonna do if the cat jumps up onto the table?

[TinselKoala]

TK,

I understand what you are saying. That was also my conclusion.
But there is more to this circuit. I recommend that you build it and test it.
It is a fun circuit to play with and probably a very useful circuit when we want
to power LED lamps from batteries. I did try some ceramic capacitors over
the output and the light in the LED bulb did increase. Also the LED brightness
goes down when I connect an antenna to the collector of the power NPN.
Need to test more on this later on.

GL.

That is my plan for the evening, after dinner. I just discovered that I have a 2sd2539 that I pulled from an old TV set, also a 2sd870, plenty of 2n2222s and 3904s, even some 2n4234 and TIP42 PNPs,  and I have a box full of all kinds of mosfets. What I don't have is one of the 3 Watt, line-powered LED bulbs.

Does anyone know the power supply circuitry inside these mains-powered LED bulbs? Is there a schematic I could look at somewhere?

[wings]

That is my plan for the evening, after dinner. I just discovered that I have a 2sd2539 that I pulled from an old TV set, also a 2sd870, plenty of 2n2222s and 3904s, even some 2n4234 and TIP42 PNPs,  and I have a box full of all kinds of mosfets. What I don't have is one of the 3 Watt, line-powered LED bulbs.

Does anyone know the power supply circuitry inside these mains-powered LED bulbs? Is there a schematic I could look at somewhere?

http://www.powerint.com/sites/default/files/PDFFiles/rdr271.pdf