Joule Thief

[resonanceman]

  Gary:
  I'm wondering if by placing any Led between the C and E of any of theses JT type circuits as an indicator light etz...can limit the amount of juice that can flow through the whole system? Thus limiting the circuit to the usable voltage and current of that led diode, to some degree, even if there is a secondary.  Isn't it better to have less restrictions, like no resistors, diodes, pots, leds, etz.. but control the voltage by lowering it, so they are not needed? As they may all be consuming part of the tiny output current and dropping the efficiency of the circuits as well as the brightness of the light.
                                       NZ

Nick

No  I  don't think that will work.

With my voltage control circuit the LED is working in a pure DC environment .  I have tested it and white LEDs light up dimly starting at about 2V
The situation between the C a d E is very different .......It is strongly pulsing .......If the JT is running  you should  be able  to light a LED between the C and E with very little indicated voltage.
It would not  be uncommon to  light a LED with only half  a volt indicated by a DMM


gary

[dasimpson]

Dasimpson

It should be possible to use a zener diode as a switch to control the voltage.
Personally I do not like relays ,they are noisy and not very reliable.

Here is a circuit I started a while back......it is not perfected yet......but I have did some basic tests.
I use a LED where you may want to use a zener diode.
I chose a LED because I wanted a charge indicator light.
A LED switches on pretty slowly as the LED gets brighter.
Like a zener a LED will pass very little voltage below a certian voltage.


The schematic  is a little confusing.
It is intended on showing just the voltage control part of the circuit.......but the battery at the top should  also be used to drive the JT that is charging the U Cap.

The U cap is shown  with dots ( terminals ) on its ends.........the rectified output of the charger  would be connected at these points.

The coil shown in the drawing is not  for charging the U cap.......it is an extra winding added to the JT.
I am sure  you have tried many windings  that prevented the JT from working......that is how this  coil works........ before the transistor  turns on the coil has very high impedance and does not really effect the circuit much......as the transistor  starts conducting this coils impedance drops, in effect  sucking the power away from the normal secondary........this power is then fed back to source.

From my experience the white LEDs I have start conducting at just  under 2V.........the variable resistor there to allow adjustment of the final cut off voltage......

I like this circuit  because it is simple .......it gives me an indicator light  and it is completely passive until  the U cap is mostly charged


I hope that this helps


gary

i was thinking of a double terminal relay then i could also have a light indicator for charge but i guess a transistor and led would work i will have to have a play see what i find ty for that

the idea was to use with solar panels,hydro,wind or just hand crank a way to tell if the bettary is charged
but as you pointed out a relay at low voltage may not work so maybe swap that for a transistor?

ok im lost on how i would wire it so that when the voltage is reached (charge) how it would shut off the supply

[NickZ]

     @ Gary:
     Thanks for your reply.  What I was referring to is:
doesn't placing an led into the primary part of an Jtc restrict the amount of power that the whole circuit would otherwise be able to output? As the led may also act like a resistor, not allowing more current to pass through it, and will blink off. I'm not talking about current or voltage control, but instead, trying to maximized the output.
  When connecting a multi cap Captret to the Jtc, any resistance will affect it in a negative way, and so, I usually have to remove the resistor, trim pot, etz. in order to try unblock any unnecessary resistance.
  I'm still trying to devise a way for the Jt to self-run by using a Captret as a source. But it seams that the Captret-Jtc is still discharging the two or three 9 volt batteries, almost as fast, if using more than one led as a load.  I've had it lighting as many as 12 leds overnight, using 8 or 10 caps. But, will only last for a much longer amount of time if only one or two low voltage Red leds are used.  Blue or white leds don't work the same with the Captret-Jt combo. although the Flat Top white leds do work well, and have a much wider degree light spread.
  @ Conradelectro and All: I've noticed that when the run batteries of the Jt are totally discharged to 0 volts, and the device is allowed to rest for a second by disconnecting the batteries, it will again light the leds bright when reconnecting the same run batteries, even if only for only a few seconds. Kinda like the Joule Ringer.  But it can do this over and over, seamingly forever.  Similar to what happens when a discharged capacitors charge bounces back.  So, this leads me to hopefully think that there is additional energy being pulled into the device by both the batteries, caps, or by the whole system.  I feel this may be an important point, especially if the effect could be improved upon somehow, so that the led light would stay on permanently.  That's the trick I'm working on now.  Any ideas... are welcome.
                                                   NZ
 
                                                                   

[resonanceman]

i was thinking of a double terminal relay then i could also have a light indicator for charge but i guess a transistor and led would work i will have to have a play see what i find ty for that

the idea was to use with solar panels,hydro,wind or just hand crank a way to tell if the bettary is charged
but as you pointed out a relay at low voltage may not work so maybe swap that for a transistor?

ok im lost on how i would wire it so that when the voltage is reached (charge) how it would shut off the supply

Dasimpson

What kind of battery will you be using?

My design is for a JT type charger...... the transistor controls the circuit indirectly.....so  a large transistor should not be needed.

With a large transistor or mosfet you could run the power charging the battery directly through the transistor........controlling it directly



gary

[resonanceman]

     @ Gary:
     Thanks for your reply.  What I was referring to is:
doesn't placing an led into the primary part of an Jtc restrict the amount of power that the whole circuit would otherwise be able to output? As the led may also act like a resistor, not allowing more current to pass through it, and will blink off. I'm not talking about current or voltage control, but instead, trying to maximized the output.
  When connecting a multi cap Captret to the Jtc, any resistance will affect it in a negative way, and so, I usually have to remove the resistor, trim pot, etz. in order to try unblock any unnecessary resistance.
  I'm still trying to devise a way for the Jt to self-run by using a Captret as a source. But it seams that the Captret-Jtc is still discharging the two or three 9 volt batteries, almost as fast, if using more than one led as a load.  I've had it lighting as many as 12 leds overnight, using 8 or 10 caps. But, will only last for a much longer amount of time if only one or two low voltage Red leds are used.  Blue or white leds don't work the same with the Captret-Jt combo. although the Flat Top white leds do work well, and have a much wider degree light spread.
  @ Conradelectro and All: I've noticed that when the run batteries of the Jt are totally discharged to 0 volts, and the device is allowed to rest for a second by disconnecting the batteries, it will again light the leds bright when reconnecting the same run batteries, even if only for only a few seconds. Kinda like the Joule Ringer.  But it can do this over and over, seamingly forever.  Similar to what happens when a discharged capacitors charge bounces back.  So, this leads me to hopefully think that there is additional energy being pulled into the device by both the batteries, caps, or by the whole system.  I feel this may be an important point, especially if the effect could be improved upon somehow, so that the led light would stay on permanently.  That's the trick I'm working on now.  Any ideas... are welcome.
                                                   NZ
 
                                                                   

Nick

Sorry I missed the part of your previous post that explained your idea of controling the JT by reducing the voltage.
I have never tried that......many of mine have been 12V

So far my best attempts at self running  have involved using feedback.
Do you have any JT coils laying around?
If so  try connecting a leg of a primary to each leg of your secondary........then connect  the secondarys of these extra JT coils to a bridge. The bridge is then connected back to the JT battery.
The other end of the primarys of these extra coils has to be connected to a load of some kind........ or another coil with enough winds to create a high inductance load.


gary