Joule Thief

[innovation_station]

@ist gadgetmall

Young thief?

if you can help make it work im in i will build it ...


scratch the t tranny for now ... 

got another idea i have a transformer easly taken apart a bigger one just primary and secondary but

what if i wound on the bobbin that is already tuned ...  a tuned primary .... hook it up as a jt ... with a 3055 and tap the secondary .... it is a lamanited core...    ideas?

ist

i guess there is no way to tune it  unless i unwind the primary ... but does it really matter ...  it may not as long as it is LOW SELFINDUCTANCE  the primary i wind ... 

dont know this is why im asking ....

waite a min .....  at a closer look it is center tapped ................................................  hummmm    lol

so this means i have 5 out wires ...   jt on primary side ....   good stuff out the secondary ..   might this work ??

[Pardon]

@ All:

For some reason (ignorance probably) I can not get a handle on measuring amps (mA's) on any of my circuits.  Yes, the books all say as many of you have said, measure amps in series, volts in parallel.  Fine, I get that.  What I don't get is how to do that?  Every time I attempt this, it does not show the draw of the circuit, it shows the amps available to be drawn upon in the battery.  No matter which circuit I use, or how many leds I am running, the measurement is the exact same as the battery alone.  So, obviously I am not doing it correctly.

To put the meter into the circuit like the books say, the circuit has to flow through the meter right?  So, I take the red probe of my meter and insert it into my breadboard just after where the battery plugs in on the + side, and then take my black probe and plug that to where the power jumper would normally go to the + side of my circuit and....it is the same as the battery.  I did it on the - side and got same results.  So, can someone please give me some simple instructions on how to do this properly?  I keep getting 1.2 amps no matter where/how I measure, and on both the Fuji and the toroid it is all the same.  Once I learn this then I can join in and see what mA's my circuits are pulling now.  I really appreciate the help, thank you in advance.

Bill

just think of your meter as a wire and use the meter in place of a wire in any circuit to test amps

so remove a wire and replace it with your meter to measure amps

i hope this helps you out

[jeanna]

Hi all,

I just went back to page 1 of this thread and followed a couple of leads given one to amigo's thread on energetic forum which had a link to a page with some interesting info. I imagine folks coming here who are looking at 220 pages, don't bother to follow all the side paths.

This page
http://cappels.org/dproj/ledpage/leddrv.htm#Rusty_Nail_Night_Light gave a recap of stuff people wrote in and others experimenting. It is an easy review of the joule thief for anyone who has not built one yet.

The reason I am posting it is that there is a paragraph where the author states that the high gain transistors will have a slower switching rate. Those high gain transistors could need a small (max 22000pF- or was it 66000pF cap) to help speed up the switching time, and give a brighter light and better life.

Perhaps this is some of what we are seeing here in our differences.

I am using the 3904 which is NOT a high gain transistor - nor is the 2N2222. So, perhaps Gadgetmall's performance increase comes from the adding the cap because his transistor might be a little slower?

We can think about this. It is getting late out there on the east coast. Good night everybody back east. Good afternoon all you folks in aussie...

========

About the yellow leds. I have been using those yellows for a few trials lately. I have been reporting dim lights and it was all looking depressing to me, then just now, I switched 3 yellows for 3 whites. now, things are looking bright again.

The value of using the yellows, however is important. I hadn't realized this so much.

I saw the first yellow of a parallel array look much brighter than the next 2. they were decidedly weaker. When I replaced the yellows with the whites, I can no longer perceive the strength difference with my eyes.

So, even though I don't really want to use those less bright yellows, they give valuable information to us.

thank you,

jeanna

PS
The circuit that now has the 3 whites is one with 10k6r after the 454r at the base along with the 103pF cap for the tank. It draws 6.4mA which is 2.13mA per light. trez cool ne c'est pas? 

[jeanna]

@IST,

Whatever happened to those copper bobbins you wound over sewing bobbins in plastic and steel? I am very curious to know how well they worked as jt?

jeanna

[Mk1]

@all

First thing is what dose this means?

And ist how many coil on the transformer? Remember this?