Lasersaber strikes again. A joule thief king ?

[TinselKoala]

This one is powered by the CR2032 or other 3v battery. The transistor is a very sensitive, high input impedance FET, a field effect transistor. The ambient electric field (DC from a charged piece of plastic, or AC from a Tesla coil or Slayer Exciter type circuit) is picked up (charges or discharges) by the Gate of the transistor which opens the channel from Drain to Source, lighting the LED with power from the battery. The field just switches the transistor, it doesn't power it.
So this is different from the electrosmog harvester, which is actually powered by resonating with the electromagnetic field of the smog source. The electrosmog harvester needs its power source to be AC RF at its resonant frequency. The Electrostatic Field detector  isn't powered by the field, and works best with a DC field produced by a static charge, either positive or negative, but it will respond to an AC field too but not as strongly.
It's a neat little circuit and should work with most any high-impedance FET. A CMOS logic gate can also be used but doesn't give the graded quasi-linear response to the field strength the way the FET does.
It's pretty  neat to be able to control the brightness of the LED by wiggling a piece of charged plastic a meter away. The charge can be from rubbing a comb thru your dry hair, or acrylic plastic against cloth, or the E field of a tesla coil, or etc.  The actuating charge builds up on the gate so this distance will change as the gate charge leaks onto or off of the gate. I tried a 10 meg resistor as pullup or pulldown for the gate, didn't work, must use at least 100 meg I guess.

[scratchrobot]

This one is powered by the CR2032 or other 3v battery. The transistor is a very sensitive, high input impedance FET, a field effect transistor. The ambient electric field (DC from a charged piece of plastic, or AC from a Tesla coil or Slayer Exciter type circuit) is picked up (charges or discharges) by the Gate of the transistor which opens the channel from Drain to Source, lighting the LED with power from the battery. The field just switches the transistor, it doesn't power it.
So this is different from the electrosmog harvester, which is actually powered by resonating with the electromagnetic field of the smog source. The electrosmog harvester needs its power source to be AC RF at its resonant frequency. The Electrostatic Field detector  isn't powered by the field, and works best with a DC field produced by a static charge, either positive or negative, but it will respond to an AC field too but not as strongly.
It's a neat little circuit and should work with most any high-impedance FET. A CMOS logic gate can also be used but doesn't give the graded quasi-linear response to the field strength the way the FET does.
It's pretty  neat to be able to control the brightness of the LED by wiggling a piece of charged plastic a meter away. The charge can be from rubbing a comb thru your dry hair, or acrylic plastic against cloth, or the E field of a tesla coil, or etc.  The actuating charge builds up on the gate so this distance will change as the gate charge leaks onto or off of the gate. I tried a 10 meg resistor as pullup or pulldown for the gate, didn't work, must use at least 100 meg I guess.

Nice little gadget, I will make one too.


Thanks for sharing.

[TinselKoala]

You're welcome. By fiddling around and touching the circuit with fingers (gate-drain and gate-source) you can "tune" the thing so that it will either light up, or turn off, the LED in response to the same kind of charge. It seems to prefer having the LED on when the charged plastic is far away and progressively dimming the LED as the charged plastic is brought closer to the Gate resistor, but this can be reversed by "precharging" the Gate with finger-resistor pullups/pulldowns. I think. The thing is interesting to play with. It makes a great charged ping-pong ball detector!

[pavqw]

My result is 3 hour runtime with 2 LEDs after some experiments with lasersaber circuit.
With some modifications I have even achieved overunity for couple of seconds!

It seems I've found very interesting phenomenon where overunity is achieved. I am not expert so it could be something very normal.
Simply it is in overunity for cca one minute where voltage is increasing (multimeter or any external source is not charging capacitor).
To get into this "mode" it is needed to add additional load into circuit so capacitor is discharging faster and after for example drop from 18V to 13V (additional load is unplugged) voltage starts to increase as in logarithmic curve (mostly it is cca +0.5V per minute). There is only one capacitor in circuit.
How is possible capacitor is charged on its own with LEDs on even for relatively short time? (measurement tools are unplugged)

I've not measured runtime of latest version because all my transistors are burned. Fortunately I've captured video but not so good, so I'll try it again with new transistors.

[TinselKoala]

Yes, it is very normal. Electrolytic capacitors have a dielectric recovery effect where they will recover charge after heavy discharges. With supercaps this effect can be very strong, definitely strong enough to cause the voltage to rise even when driving small loads. I've demonstrated this myself in videos, I think there is one posted earlier in this thread.