Open PCB Tesla coil

Very Simple Tesla Coil ... 3 components only = LED, BD243 transistor and 82K resistor

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I am inspired with this is much more easy, effective is far away from original

Manufactured in Manufacturing this type of board is not easy.
Boards form JLC works 
without problems and additional payments.

  • Input power 24V - 35V from 5V USB powered step up converter or notebook 19V power supply.
  • Frequency 2Mhz - 4Mhz
  • No special components, just LED, BD243 transistor and 82K resistor

Development status:

  • v1 7/7mill almost not working
  • v2 on video working, 100turns, no visible sparks
  • v3 on pictures 160turns, works much better but no sparks
  • v4 ready for manufacture 150x150mm PCB, 240 turns, I hope it can work much better


Hacked scrip to make bigger coils .... etc 350 turns :)

ulp - 23.17 kB - 04/13/2019 at 07:31


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Sophi Kravitz wrote 04/09/2019 at 12:56 point

Good comments @K.C. Lee I never looked for input capacitance on datasheet either

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Anton Bolabolchenko wrote 04/09/2019 at 12:03 point


And how about using several layers of pcbs? (not multi layer pcb, but stack of 2-3 pcbs)

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K.C. Lee wrote 04/09/2019 at 03:21 point

Gut feel tells me that your BD243 might be too slow for your '2MHz - 4MHz'

First clue:  they don't specifically say RF Power amplifier on the datasheet nor mention input capacitances.  It is listed as 'NPN SILICON POWER TRANSISTORS'

ton Turn-on time 0.3 µs (typ)
toff Turn-off time 1 µs (typ) 

i.e. it would switch at best at 1.3us period which is 770kHz.

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bobricius wrote 04/09/2019 at 05:56 point

Thanks for advice, I measure this frequency with multimeter, It is close to original project.

Which transistor you suggesting ? My schematic is same like on Chinese kits. Or is better use MOSFET+ driver ?

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K.C. Lee wrote 04/09/2019 at 11:48 point

It is not easy to switch MOSFET at MHz range because MOSFET have huge input capacitance.  Even a small device can have on order of 1nF. 
Homework: figure out the AC impedance of that at MHz range, what currents you'll need to drive that.  Use lTSpice

Rather than fighting the capacitance, people that make high frequency Tesla coils (HF-SSTC) use Class E drivers.

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K.C. Lee wrote 04/09/2019 at 12:08 point

You are playing with high frequency stuff, always consider the AC parameters and parasitics.  :P 

As for BJT selections, use the parameter table at digikey or browse the BJT manufacturers device trees usually sorted by end applications.

 Higher current parts have lower hfe and are likely more difficult to drive.
If the datasheet don't talk about input capacitance, Gain bandwidth, go else where.

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bobricius wrote 04/10/2019 at 20:10 point

Thanks for explanation, I try another transistor.

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