Haefely Apero, January 19th 1999

Click on the photos for bigger picture. 
The pictures were taken on the occasion of a TC demo, which I had the honour of
presenting to the almost complete HAEFELY development engineering team, in my home.
( This company is known as a world-class developer & manufacturer of HV test equipment )
Sparklength to ground rod was about d = 0.6m+

Kurt introducing his
small Tesla coil
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two terminals...
(...yes, that's me)
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spark production
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Andi has made
my first spark pic's
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spark gaps
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"jonic motor"
was demonstrated
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relaxed at apero
relaxed at
apero time
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Haefely engineers
...again the Haefely
engineering team
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The state of the Tesla coil, this time, was as follows:
  • Power supply: Neon sign transformer 9kV/100mA, fed via variac 10A
  • Protection Filter: 2 x (47mH+3kOhm) and 1nF bypass cap // NST
  • RQ-gap with 5 active gaps only, corresponding to 3.5mm gapwidth.
  • Capacitor: 16.8nF double layered epoxy-PCB in transformer oil
  • Primary: 15 turns 30deg. saucer (L ~90uH), tapped at 9.5 turns (L ~ 20uH)
  • Secondary: D=12cm (~5"), H=58.5cm (23"), 921 turns (L ~19mH)
  • Top terminal: dia.=25cm silver-plated metal sphere, 9cm above coil
  • Resonance at 275kHz (secondary: 373kHz without top load)
  • Input power not mesured 
  • Sparklength: within range of 0.5m...0.65m ( 20"...25" )
  • Click for circuit sketch