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[Thaelin]

   As usual, it didn't post with the message so here is the drawing I am referring to

thaelin

[nievesoliveras]

   Hi Jesus:
   I quoted this message as it has the circuit in point. I hope it comes through with the post.
As I look at it, you are using NPN transistors and the emitter is tied to positive on the batteries.
This is reverse to how it would be. The emitter should be negative. The best rule of thumb is to
see movement from negative to positive and should always flow against the arrow direction. I have
used 3055's to switch both the negative and positive side, just have to be sure the emitter is towards
ground side.

thaelin

Thank you @thaelin !

You know on the "jule thief" topic, a member called @jeanna made a test last year with an npn transistor, using it with the emitter and collector on the wrong polarity and it worked for her.
So taking that test into account, I used the npn transistors on that circuit as a relay for the positive current.

The idea is that when the joule thief transistor is on, two transistors will get on at the same time. One allowing the positive current from one battery to the joule thief to be used as source current, the other allowing the emf current from the joule thief collector diode to charge the other battery.
Then when the transistor is off, its emitter side diode should trigger the other two transistors, which will reverse the batteries chosen for source and charge.

I discovered on my tests that the joule thief has no positive current to start the oscillations.
I am looking for a solution.

I made another logic circuit, but the same problem showed up. The joule thief does not have a starting voltage.

Will you post the circuit you did with the 2n3055s?

Jesus

[Mk1]

@jesus

On my Jt i work both ways npn in reverse it is still npn , and also my mk4 has 2 jt on it with one npn and on pnp , both circuit are the same but one is feeding fro the positive rail and the other negative battery rail.
Only on half of the circuit need to be powered for both circuit to be lighting led.

Keep the good work !

I am fallowing and hope to be able to help!

Mark

[nievesoliveras]

@jesus

On my Jt i work both ways npn in reverse it is still npn , and also my mk4 has 2 jt on it with one npn and on pnp , both circuit are the same but one is feeding fro the positive rail and the other negative battery rail.
Only on half of the circuit need to be powered for both circuit to be lighting led.

Keep the good work !

I am fallowing and hope to be able to help!

Mark

Thank you @mk1 !

You confirmed that the npn could be used with the emitter to the positive or the negative.
The only thing that cannot be changed is the base connection to the positive.

The same way with the pnp transistor, you can connect the emitter and the collector on either pole,
but the base will work only with a negative pole.

Jesus

[nievesoliveras]

@all

On my logic circuits study I learnt that this circuit added is a sure oscillator. But I get the same problem I had with the other one and is that the joule thief does not have a starting voltage to oscillate.

Any suggestions?

Jesus