Joule Thief

[resonanceman]

@ Gary (resonanceman): I would like to ask you to explain your suggestion (see the above quote) in other words or with a drawing. It sounds very interesting but I do not understand it (may be because I am not an English speaker).


@ all the nice commenters: the design of the flash light is awkward and the thing is clumsy, one could do much better with a little care and diligence. It is more an experiment than a practical device. Let's call it a retro-flash-light from the Frankenstein era.


I found that a slowly diminishing battery poses a problem when designing a Joule Thief type circuit

My design idea was a secondary and the jumper to light 1 to 5 LEDs according to the remaining power and voltage in a slowly draining AAA battery.

There is huge difference between a JT that gets 1.5 Volt or one that should run on 0.6 Volt. With 1.5 Volt a lot is possible, up to lighting neons or fluorescent lights. But below 1 Volt the world becomes small, because not only the voltage is low but also the amperage that can be drawn from the slowly dying battery has diminished.

Air cores: I always succeed to get high frequencies with air cores (between 100 KHz and several MHz) and I achieve only low frequencies with toroids (6 KHz to 15 KHz).

Secondary winding: for a very low power and low voltage JT (e.g. 0.6 Volt, 0.3 mA, low power red LED) one should not use a secondary. But once sufficient power (at least 20 mA) and enough voltage (at least 1.2 Volt) are available one should use a secondary and the result will be a nice high voltage on the secondary to light many LEDs.


Another idea (see drawing): as long as two AAA batteries are still fairly strong (down to 0.9 Volt) one uses two AAA batteries in parallel, but once the voltage drops below 0.9 Volt, one switches the two AAA batteries to a series connection (with a toggle switch, not automatically).

Greetings, Conrad

Conrad

The whole point  I was trying to make is that the paper  tube that  you wound your coil on is probably not needed.
If you eliminate  the paper tube you can make your  unit much smaller .


Yesterday I was working on a bigger air core coil.
It did not  work out well.   I was shooting for something  along the lines of a Jeanna light .  At least 450 V and some power to back  it up.
I  ended up with lots of voltage but no power.
Probably  problems with the primary....my base primary was only 5 ft.
I was trying to decide  how to go about  fixing  it  when  I remembered your  jumper setup ........  Then I remembered  a coil I made years ago. ........this coil  had 10 taps ........It was intended  to help me  test for  how different impedances affected the circuits I was playing  with at the time.
After a while I found that I could pick  any 3 of the 10  taps  .... then  put the battery + on the middle one  and  use the other 2  for the  JT coil  connections.
Then  I decided   to make a test  primary wire....... I twisted  a  piece  of mag wire together  every 5 ft to make   my taps. ( first picture )

I numbered all the  taps.......20 of them
I then wound  the whole thing around my  coil.
The result is the second picture.
All i have to do  now is sand  the varnish  off the taps I want to use and connect them  with alligator clips  to my transistor,.

At 100 ft  this  primary is  probably overkill.......but...... if this coil works out  pretty well  I will replace this primary with a perminant primary and  try a bigger coil.

I was thinking  about your project.......if you want maximum versatility you might try adding  some taps and one of those jumper things  to your coil..... different  input voltages  need different  primary lengths.....also....... with or without a secondary changes  things.......without  a secondary  a longer Emiter  leg  on the primary  to maximize voltage.

Back to  my test primary.
I think I will start by connecting my  base  to tap 1  battery + to tap 10 and emitter to tap 20.......using all 100 ft of  my primary.
I will see where this puts me...... I will then  try moving the  battery +  closer  and closer to tap  1 ........when  the power  starts to drop off  the base leg is to short.
Then I will start shortening   the emitter leg one tap at a time until I get  the best  output I can get.


gary

[nievesoliveras]

@ Jesus (nievesoliveras):
...
Really strange way of switching the transistor and I do not see right away how the second battery can be charged without a diode.
...
Greetings, Conrad

The Led is a diode. But if it does not work with your circuit, just change it for a regular diode.

Almost all the electronic parts that I was originally using, adquired a blue moss when I left them aside for a long time. That blue thing corrodes the connections and the parts are useless now.

I am waiting for some controllers I sent for.

@resomamceman
Good air coil. Just it looks a litle strange.

Jesus

[Pirate88179]

Gary:

For what it is worth, on my replication of the Jeanna circuit, I used only 4 turns on the primary as did Lidmotor.  I know I had 330 turns, give or take, on the secondary but I can't remember how many on the collector coil...I think it was like 6 or 8 maybe.

Bill

[resonanceman]

@resomamceman
Good air coil. Just it looks a litle strange.

Jesus

Jesus

Yes it looks pretty strange now....... once I find out what length of primary I need I will replace the big primary with all the taps and it will look alot more normal.

gary

[resonanceman]

Gary:

For what it is worth, on my replication of the Jeanna circuit, I used only 4 turns on the primary as did Lidmotor.  I know I had 330 turns, give or take, on the secondary but I can't remember how many on the collector coil...I think it was like 6 or 8 maybe.

Bill

Bill

Yes that sounds right.

I am trying to use an air core where you used a big toroid.,......it is going to take  a little more wire.
This kind of coil seems  similar to  my LM coils in many ways.......If I remember right the LMs took about 8 wraps bifilar

anyway......time will tell if it is going to work.

I have been working on other things most of the day.,,,,,,, testing time is coming up soon




gary