Joule theif : try out !

[mscoffman]

A Self Boostrapping Manual Start Circuit.

It might be fun to use a manual SPDT switch as a multipress trigger AC source
from a low voltage DC higher current supply to a small Crockroft Walton Voltage
Mutiplier. Once a client higher voltage Joule Thief starts running it could serve as
AC clock source for running the voltage multiplier itself.

This could serve as a stardard way to deep six carbon/zinc primary batteries from
"emergency" circuit designs for a crystal cell battery per spec.


:S:MarkSCoffman

[TinselKoala]

Two of my JTs:

The NE2HVJT lighting up six NE-2s in series from a depleted AAA battery, and another HVJT lighting up an incandescent bulb and a NE2 simultaneously, on 3V input.

So I'm going to say that "performance" depends on what you are trying to do. If you are trying to see how long you can get a visible glow in an LED or operate at the lowest possible input voltage that's one thing, or maybe two. If you are trying to get max voltage and fast rise-fall times in the oscillator's output, that's another. If you are trying to operate the transistor at its best efficiency (max gain for minimum base-emitter current) that is something yet again different.

The JT problem space was pretty completely explored back in the old JT threads where Jeanna was posting a lot of her research. People even stripped turns one at a time off coils to find optimum winding ratios for what they were doing. Some remarkable results were achieved, lighting up CFLs to very reasonable brightnesses on tiny input voltages and currents. Before anyone starts re-inventing the wheel, I suggest digging out those old threads and skimming over them, you might discover that the dedicated JT builders know more than you think, already.

[Vortex1]

Two of my JTs:

The NE2HVJT lighting up six NE-2s in series from a depleted AAA battery, and another HVJT lighting up an incandescent bulb and a NE2 simultaneously, on 3V input.

So I'm going to say that "performance" depends on what you are trying to do. If you are trying to see how long you can get a visible glow in an LED or operate at the lowest possible input voltage that's one thing, or maybe two. If you are trying to get max voltage and fast rise-fall times in the oscillator's output, that's another. If you are trying to operate the transistor at its best efficiency (max gain for minimum base-emitter current) that is something yet again different.

The JT problem space was pretty completely explored back in the old JT threads where Jeanna was posting a lot of her research. People even stripped turns one at a time off coils to find optimum winding ratios for what they were doing. Some remarkable results were achieved, lighting up CFLs to very reasonable brightnesses on tiny input voltages and currents. Before anyone starts re-inventing the wheel, I suggest digging out those old threads and skimming over them, you might discover that the dedicated JT builders know more than you think, already.

I agree it all depends on what you want to do. In addition to digging out those old threads, I suggest folks dig out some old books, because this subject was fairly thoroughly engineered before most of us were born, back when it was called an inductively coupled oscillator, saturating core multivibrator,  or blocking oscillator (and many more names) in the vacuum tube days.

I built my first miniature blocking oscillator using a CK722 transistor in the mid 50's,(when it went to $0.99) to make a portable 4' flourescent tube light and before that, several versions of a vacuum tube blocking oscillator.

The CK722 was the first low cost junction transistor available to the general public. It was a PNP germanium small signal unit. Developed by Norman Krim, it was introduced by Raytheon in early 1953 for $7.60 each; the price was reduced to $3.50 in late 1954 and to $0.99 in 1956.

[Farmhand]

Reading through old threads is unfortunately a good way to waste time and read a lot of misconceptions, these sites have lots of threads with lots of posts not worth the time to read and a few good posts in amongst them. Ever tried it ?

I just want a low part count easy to make setup that can drive some LED'S to get usable light from old AAA and AA alkaline batteries, as well as charge some odd tiny batteries with low current.

I take on board the diode advice.

Considering if I was to stick to under 4 volts input. Can I ask why it is that the base drive is inefficient ? Like what are the reasons, is the voltage applied to the base too high or is the current too high or too low ?

The circuit has been running for 24 hours now driving 4 x 5 mm LED's and trickling a pair of AAA 700 mAh, with two old 900 mAh NiMH AAA batteries as supply, now considering that the garden path lamps using one 5 mm LED deplete the 1 x 700 mAh battery before dawn, but in this setup the two 900 mAh AAA's are still at 2.44 volts which is still over the nominal 1.2 volts of the batteries, I think it is doing ok. Now I do realize that the solar garden lamps probably do not charge the battery well because it seems this circuit (like other pulsing circuits) apply a better charging voltage and it doesn't drop off like the sun so charging is not halted and the batteries gain some working condition, the tiny 20 mAh NiMH batteries I have responded well to charging by JT but not so well with DC.

I think the AAA NiMH batts I'm charging now will take a charge from the wall charger better after trickling on the JT for a day or two.

When I make the little PCB I'll use a connector to attach the load LED/s so it can be swapped out for the load battery or the load battery can be connected in series with other loads ect.

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[Farmhand]

One of the main problems as I see it on these sites is that the discussion and chit chat gets mixed in with the technical info. In reality the entire sites are a big "chat box" with "sub sections" of chat that may or may not contain "chat" that has information relative to the issue a person is dealing with.

There is an inherent problem with suggesting folks lookup old "chat" and that is that it is just that "chat" how does a new experimenter differentiate between "chat" and technical info when the technical info is stuck in the middle of thousands of words of chat ?

Until a solution is found people will just continue to ask new questions and chat, increasing the issue.

Along with oversized images it make reading the threads difficult and time consuming.

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