Jewel Thief Help

[team_nightstalker]

I'm attaching a picture of my board as i can't figure out why it is not working.

 

[ronsimpson]

A little information will help!
What do you want it to do?
Schematic?
Are you trying to light an LED with a 1.5 volt battery?
Transformer? 1:1 windings? Inductance?
That transistor? Is it a transistor?
I can clearly see from the photo that your battery ran down! LOL Help us help you.

 

[ericgibbs]

I'm attaching a picture of my board as i can't figure out why it is not working.

hi,
With the Joule Thief its very important that the transformer windings are in the correct sense, else it will not oscillate.

Looking at the pix, it appears you have the conenctions to transistor and LED ok, but I cant check the pin polarity.

 

[ericgibbs]

A little information will help!
What do you want it to do?
Schematic?
Are you trying to light an LED with a 1.5 volt battery?
Transformer? 1:1 windings? Inductance?
That transistor? Is it a transistor?
I can clearly see from the photo that your battery ran down! LOL Help us help you.

hi Ron,
Its a device called a 'Joule Thief' it runs on a 'flat' battery until it drains all the battery. Drives an LED.

Lotsa Googles

 

[blueroomelectronics]

It's actually called a Joule Thief
**broken link removed**
**broken link removed**

 

[team_nightstalker]

i also found this **broken link removed**
maybe my windings are off? crap man i have wound that thing 6 times now. i'll redo the whole thing and re upload a pic later.

 

[ronsimpson]

OK thanks Eric “Jewel Thief” did not mean anything to me. I should have researched it. Now that I am researching it, my searches lead back to this forum where I am the one in the dark. I draw the schematic (from the proto-board) but why when NightStalker had it.

Now I see it! EPE November 1999. I have those in a pile on the floor.

 

[Hero999]

The correct spelling is "Joul Thief"

Try swapping the connections to one of the coils.

Also bear in mind that this circuit is designed to power a white LED, not a yellow LED so you might want to think about adding a series resistor with the LED or it might overheat. Yellow LEDs have turn on voltages of around 2.1V and white LEDs have forward voltages of around 3.5V which is quite a large difference.

 

[team_nightstalker]

could it be because i'm using a 1K resistor?

 

[Hero999]

No, that's the value you're supposed to use!

 

[team_nightstalker]

ok here is the rewire. i do have a white LED as well. even swapped the coil wires a1 with a2. i know i have a1, a2, b1, b2 right.

 

[team_nightstalker]

ok the transistor is a radio crap 3906. that should not be a problem either should it. it's just basically a relay.

 

[ericgibbs]

could it be because i'm using a 1K resistor?

hi,
No, a 1K0 is required in the base circuit.

Disconnect the transformer and use an ohm meter to measure the transformer, to ensure that you have not got the windings crossed over.

When its connected, what dc voltages do you measure at the transistor base and collector?

Is the LED ok and the correct way round, if its been connected in reverse it could have died.

 

[Hero999]

I thought he was talkging about the 1k base resistor.

Have you checked the connectiond between the components using a multimeter?

Breadboard has a nasty habit of failing to make good connections.

EDIT:
Have you checked both the LED and transistor?

The transistor might fail if the LED becomes disconnected and the LED might fail if it's connected backwards.

 

[team_nightstalker]

ok just tried the 3904 NPN and a 2222a NPN as the 3906 is a pnp. man i'm all confused.

 

[team_nightstalker]

think i'm going to radio shack to pic up some new parts.

 

[ericgibbs]

ok just tried the 3904 NPN and a 2222a NPN as the 3906 is a pnp. man i'm all confused.

The transistor is a NPN type,,, some Joule Thief circuits use a BC547, so get an equivalent type.

Where are the voltage measurements we asked for?

Like to help.

 

[team_nightstalker]

will get you the measure ments later. my batter in my multi died. man what a day. when it rains it poors

 

[team_nightstalker]

where is a good place online to get components? i hate radio crap. over priced retialers. i'm in Central NY state. anything around me with quick shipping?

 

[audioguru]

Now that you have the correct NPN transistor you can try swapping the wires from one winding around.

Is the LED connected with the correct polarity? The wire beside the flat on the case connects to 0V.

Use a new alkaline battery cell, not a lousy old "heavy duty" carbon-zinc piece of junk.

Don't solder to a battery cell. Use a battery holder.