Joule Thief

[electricme]

@xee2

@ electricme

I thought it was to reduce radio interference? The resistor is always connected inside of the coil, there is no way to bypass it. I have always wondered about why they would put a resistor in the coil. I just do not know enough about cars to know for sure. Thanks for your feedback.

No, the resistor was not to reduce interference.
As the engine cranks, the starter motor draws almost all the energy (amps) from the battery.
As amps rises, voltage decreases, if the battery is weaker than normal, say in a cold climate for instance, the coil may not have enough power to make a spark to jump the gap inside the sparkplug.
So the 20watt resistor is bypassed only during engine cranking, the extra benefit is the coil doesn't run so hot, so lasts longer.

Then as the engine runs, the resistor is switched in series with the ignition coil primary, it drops the voltage to the ignition coil while the engine is running.

--------------------

The suppression of any spikes was done by 15,000 ohm resistors placed midway in the ignition wires, then special resistance carbon impregnated leads were developed.
Capacitors were placed across any other electric motor that ran in the vehicle, eg wiper motor, electric window winders, solenoids etc.

jim

[WilbyInebriated]

someone asked about modding a maglight to use a jt, i'm not even sure it was in this thread or another jt related thread. my apologies to whomever it was as i didn't have the time to respond when you asked it and then subsequently forgot about it. my bad. i hope you read this post and it helps.

here is a circuit for use in a maglight...
http://www.overunity.com/index.php?topic=6123.msg167898#msg167898

here is a picture of one of my battery replacement jt's. i told bill i would find a camera and post a picture of it some 600 pages ago... better late than never i guess. it is usually wrapped in electrical tape to look nicer but i removed what i could to make it more visible. the black piece of plastic is from a DMM probe. the transistor is inside the black plastic, the coil and core is just to the left of where the transistor is tucked inside.

[Pirate88179]

Wilby:

It does my heart good to see pictures like that.  I am starting to get quite a collection of devices designed to run on 3 or 4 AA's and now only use 1 plus the JT circuit.  If this keeps up, pretty soon we will have to bail out the battery companies, ha ha.

While you are digging around and have your camera, I would like to know more about your CCFL Light Beer device.  I still have my kegs (empty now) and have not done anything with them.  Do you think a Jeanna Light toroid circuit would light a CCFL?

Thanks man,

Bill

[WilbyInebriated]

Wilby:

It does my heart good to see pictures like that.  I am starting to get quite a collection of devices designed to run on 3 or 4 AA's and now only use 1 plus the JT circuit.  If this keeps up, pretty soon we will have to bail out the battery companies, ha ha.

While you are digging around and have your camera, I would like to know more about your CCFL Light Beer device.  I still have my kegs (empty now) and have not done anything with them.  Do you think a Jeanna Light toroid circuit would light a CCFL?

Thanks man,

Bill

actually heairbear brought his camera over a few weeks ago when he stopped over to chew the fat and took that picture. the circuit i powered the beerlight with was a royer oscillator running off a cell phone battery, i think he is stopping by later tonight so if there was something specific you wanted to see close up i can fire off a msg and ask him to bring his camera. last i recall reading was 2000+ V from jeanna's circuit? i think that would do it, that's close to what a bug zapper circuit puts out and those will light ccfl's.

i'll also see if i can get a picture of my high voltage circuit lighting up an incandescent bulb with one wire and no spark gap...

[Pirate88179]

Wilby:

Thanks, that would be great!  I am sure others here would be interested as well.

Bill