Lasersaber strikes again. A joule thief king ?

[pavqw]

What transistor do you recommend to do experiments with JT/SJR? I've used MPSA18 but all are burned now I want to order some transistor from Farnell but this one is not available in low quantity.
I am searching for something very efficient but available, cost is not relevant. I prefer NPN, it could be for low power.
Also do you have tip for ferrite core?

Thanks

[TinselKoala]

What transistor do you recommend to do experiments with JT/SJR? I've used MPSA18 but all are burned now I want to order some transistor from Farnell but this one is not available in low quantity.
I am searching for something very efficient but available, cost is not relevant. I prefer NPN, it could be for low power.
Also do you have tip for ferrite core?

Thanks

Most any NPN will work in a basic JT circuit. Most any combination of windings on most any bit of ferrite will work. Once you have a setup that works, you can start changing things around to get the best efficiency. Turns ratio, wire size, ferrite material, ferrite geometry, base resistor, capacitors, all of these and more are the variables that will determine your efficiency. Different transistors will work differently in different circuits.

Here's a video showing a bunch of different NPN transistors that will work, most of them obtained for free from CRT tv chassis.
http://www.youtube.com/watch?v=tuFWC-yyIyU

Here's another video showing my latest SooperLooper JT with some transistor data.
http://www.youtube.com/watch?v=BHI7LnVWBlY
Transistors tested in the above system, with "start" and "stop" voltages as described in the video:
2n2222a  0.436, 0.111
BC337-25  0.420, 0.102
2SC3198  0.443, 0.111
MPSA18  0.430, 0.123
2n3904  0.491, 0.177
2n3704  0.434, 0.109
1802 N711  0.425, 0.100
200-32 F340  0.427, 0.127
CEN PN3643  0.428, 0.135
9287 N710 EBC  0.436, 0.103
2n2219  0.434, 0.142
2n2219a  0.417, 0.134
2n3053  0.424, 0.127

My "Current" favorites for low voltage JTs are MPSA18, BC337-25, 2sc3198, and 2n2222a (metal can).
For high voltage (neon lights) use 2n3055 or 13003 or similar.

I have just started testing the 2sk170 FETs that I received a couple of days ago, in conradelectro's circuit.

[TinselKoala]

Two great Ebay sellers are "thaishine" and "utsource". Check them for small quantities of the desired transistors.

[pavqw]

Thank you very much! I've ordered some of them from Farnell, it should arrive in 1 day. I'll try 1F capacitor too

[d3x0r]

Charging a 3000F cap; never finished charging... moved down to 100F instead to experiment...

https://www.youtube.com/watch?v=AmABqSn9ocw


Lasersaber is using 11V 1F caps which are Nek/tokin; I found them for $6.99 at a Cute Digi... they had some components but not many.
Illinois Capacitor, Inc. makes 25F 2.7V I found at allied elec for $3.39.  put 4 in series and you get 10.8V, 6.25F for $12... slightly more than double the cost for 6x the capacitance   But these were clearance....