Joule Thief

[PaulLowrance]

Here's my results of testing gadgetmalls circuit, or at least the closest I can presently get to it. I don't have his toroid, but I'm using a good toroid with high permeability.

The previous quick & dirty method that I used is not to be taken seriously, but this method has the potential of being very accurate. The method consist of using a resistor for the load, and measuring the R's temperature, which we'll call Tr. Then doing the control experiment, which consists of connecting the resistor directly to a power supply, and then increasing the current until the resistor temperature stabilizes at Tr.

An elaborate setup would use a closed system that maintains a fixed temperature. I did not go that far. Also I did not dig out the ridiculously sensitive temperature equipment.

A 100 ohm carbon resistor was used as the load. The voltage across the JT was 1.559 volts DC, and the current was 74.3mA DC, for a total of 116mW. The control experiment showed that it took only 93.3mW to bring the resistor to the same temperature.

This comes to 80.4% efficient.

This JT was about 80% efficient, but maybe there's some tweaks to improve this?

Regards,
Paul

[gadgetmall]

Here's my results of testing gadgetmalls circuit, or at least the closest I can presently get to it. I don't have his toroid, but I'm using a good toroid with high permeability.

The previous quick & dirty method that I used is not to be taken seriously, but this method has the potential of being very accurate. The method consist of using a resistor for the load, and measuring the R's temperature, which we'll call Tr. Then doing the control experiment, which consists of connecting the resistor directly to a power supply, and then increasing the current until the resistor temperature stabilizes at Tr.

An elaborate setup would use a closed system that maintains a fixed temperature. I did not go that far. Also I did not dig out the ridiculously sensitive temperature equipment.

A 100 ohm carbon resistor was used as the load. The voltage across the JT was 1.559 volts DC, and the current was 74.3mA DC, for a total of 116mW. The control experiment showed that it took only 93.3mW to bring the resistor to the same temperature.

This comes to 80.4% efficient.

This JT was about 80% efficient, but maybe there's some tweaks to improve this?

Regards,
Paul

I haven't hooked  a scope to it yet but  ground the grouns and use a 900k resistor . that should not load the jt at all . Also the Diode is converting half the spikes to voltage . If you read the Ce with a meter you only see about 2.5 volts . put the diode on and it should be about 21 volts , Put another diode on the emmiter and you should see about 25 volts  . put a bridge  on the Eb and you see about 30 volts . As i said before i read The current with a 1 ohm resistor in series with the battery and adjust it 13 ma to get the above readings . IF your toroid is close to the same permeability then you should see at least these volts if not higher @ 13 ma draw . ..  My lowest Jt is pulling 0.80 milliamps  @ 0.18volts and runs 4 white leds in parallel . This one runs all the time 24 7 now since i built it . It uses an obsolete transistor and a true museum piece  HEP 638 . I found one on ebay a few weeks ago in the original box and bid 50 dollars on it . it went for 220.00 Us    So this transistor is extremely Valuable germanium . Most of the germanium i sold to cheap . Some that Jeanna has are worth 100's of dollars i found out later ..  there is only one on the internet here http://www.mistersprockets.com/hep638-p-20142.html

Its a fake ,a cross no where near the value  or the guy has no idea whats its worth . you can easily make 5 times that
.
ALso It's so rare there is no spec sheet on the internet at all /
Gadget

[Pirate88179]

Paul:

Great testing idea.  Where were you getting the 1.55 volts from?  Was that the input from a battery?  If that was your output, it should be somewhere way higher than that.  The basic JT in its simple form should put out around 15-30 volts depending upon how you make it.  Input on this could be anywhere from 1.5 volts down to about .35 volts.

Bill

[jadaro2600]

The circuit goes into resonance rather quickly, it's working to its specifications.. I assume you are tuning it to optimum output?

The circuit will still be in resonance, I think what we're trying to assume here is that tuning is the key, not resonance.  The circuit will go into whatever resonance it's been adjusted for..

i.e. "Resonance at configuration X vs resonance at configuration Y" ...etc.

- - - - -

Is there a transistor that will open the Source-Drain channel when a voltage is applied?

[broli]

The circuit will go into whatever resonance it's been adjusted for..

This is true but it doesn't mean it's optimal, if you hit the toroid and record the sound with a microphone it might peak at a certain frequency this is its natural vibration that you would like to work towards. Electrical frequency of the circuit depends on saturation level of either toroid or transistor.

Is there a transistor that will open the Source-Drain channel when a voltage is applied?

I think you're looking for mosfets.