Lasersaber strikes again. A joule thief king ?

[MarkE]

I made a Joule Ringer with my big coil and a BC547C transistor which needs very little power (4.4 Volt at 2 mA --> ~0.01 Watt) to light up a 220V 0.7W LED lamp fairly bright. I could not find any good use for the third winding, so it is not connected to anything.

The LED lamp can be connected to the positive rail as indicated in the attached drawing, but one can as well connect it to the negative rail. I did not see any difference in power consumption or LED lamp brightness. (I guess that the BC547C should not be driven with 12 Volt. The aim is a 1 to 1.5 Volt circuit, but this will need thinner wire and more turns for the windings eventually.)

This is nothing new, just some low power Joule Ringer. But next week I will dismantle this coil and wind it again with the same wire and the same number of turns but with two copper strips as I indicated in my post above http://www.overunity.com/14591/lasesaber-strikes-again-a-joule-thief-king/msg401739/#msg401739

This should then show whether the copper strips change anything in an interesting way. I will lead out a wire from each of the two copper strips to be able to connect them in several ways to the windings. The first copper strip will be on the core, below the first winding (which is driven by the transistor). The second copper strip will be over the second winding (which drives the LED lamp and is connected to the base of the transistor).

I will omit the third winding at first (it can be added later, but might not fit on the core together with the copper strips, needs thinner wire).

If the copper strips are good for something they should help in any oscillator circuit. But this unfounded guess work might be wrong.

Greetings, Conrad

I am surprised that you are not burning out the transistor due to excessive reverse Vbe.  I would recommend either a series Schottky diode to the transistor base and a light pull down from the base to emitter of say 100K or so, or a series current limiting resistor and a signal diode like a 1N4148 with the cathode on the base and anode on the emitter.  The shunt configuration should allow a lower starting voltage.

[SkyWatcher123]

Hi folks, Hi nickz, nice to see you again, hope your devices are lighting up your life.
Since I've never built an air coil as big as this one will be when it's done, that's one of the reasons I'm trying it.
Just started winding, will take me a few days, since the wire is on rectangular wood formers, so slow going.
Here is a pic so far of progress and it is very close to the ideal brooks coil ratio.

peace love light

[d3x0r]

Lasersaber progress https://www.youtube.com/watch?v=6B79UJGoNJE 

[ramset]

Also Slider has an ongoing replication/modification
here [19 minute run time so far]

http://www.youtube.com/watch?v=3g5_x1TQsPA&list=UUFqtTvDJtJRQFdRxwiCAWXw

thx
Chet

[conradelektro]

I am surprised that you are not burning out the transistor due to excessive reverse Vbe.  I would recommend either a series Schottky diode to the transistor base and a light pull down from the base to emitter of say 100K or so, or a series current limiting resistor and a signal diode like a 1N4148 with the cathode on the base and anode on the emitter.  The shunt configuration should allow a lower starting voltage.

@MarkE:

In this circuit http://www.overunity.com/14591/lasesaber-strikes-again-a-joule-thief-king/msg401872/#msg401872 (which you seem to refer to) there is a LED with the cathode on the base and anode on the emitter limiting the reverse Vbe to -2 Volt. A 1N4148, as you suggest, would be better (Vbe of -0.7 V).

With a 100K resistor in front of the base of the transistor and a 1N4148 to limit Vbe (see the attached circuit and photo, I think you called it the "shunt configuration") I can now run the circuit with 1.2 to 1.5 V from a AAA battery. But the power draw is considerable, 20 to 30 mA at 1.2 to 1.5 V. The LED lamp gives useful light (although far from nominal brightness).

Higher Voltages cause even more power draw like 70 mA at 6 Volt. But this could be a nice flash light circuit with a single AAA battery.

Thank you for the suggestions.

I am waiting for the circuit diagram of Lasersaber's latest circuit http://www.youtube.com/watch?v=6B79UJGoNJE before dismantling the coil (in order to add copper strips), I want to do some tests too (without copper strips).

I think that Lasersaber's 2N1304 Germanium NPN transistor can switch with a very low base current, but the BC547C should have similar capabilities. But I did not understand from his video how he connected everything, therefore I have to wait for his circuit diagram. I am using a different coil core than he does, but that should make it interesting. Is it the core or is it the copper strips, which allows for such a low power consumption.   

Greetings, Conrad