The traditional CD ignition uses a switching power supply to
 develop  the 300 volts used to charge the capacitor. That is the
 main reason  they are so expensive. I come up with one idea a day.
 Not always  new however. I spent quite a bit of time trying to build
 such  a switching supply with less than satisfactory results. It worked
  most of the time but not always.

  I used a chip called a half bridge driver that was supposed to do
 the job.  Every once in a while it would turn on both the high side
 and low side switches  with disastrous results.  When hooked to a
 car battery as much as 100 amps  could flow through the circuit.
 Not a good thing. Of course it literally  exploded. The early
 Aussie CD ignition had the same problems.

  My idea is use a cheap AVR board to do the half bridge driver job and
  things can be controlled down to several nanoseconds. Both
 switches can  never be on at the same time.  Also the AVR's A to D's

 can be used to monitor what is happening and shut the silly thing
 off if  things start to get out of hand.

  Way back in the 70's and 80's we used the circuit
  called "DC-power-supply" which was fairly reliable. I think Heath
 Kit was making  a CD ignition kit in those days. My use of CD's goes
 back further than that to the  days of the vacuum tube thyratron in
 the 1950's.

  Paul Lamar

 What is this thing you call 'vacuum tube?'

  John Duncan

 http://en.wikipedia.org/wiki/**Vacuum_tube<http://en.wikipedia.org/wiki/Vacuum_tube

 "In electronics, a vacuum tube, electron tube (in North America), or
 thermionic valve (elsewhere, especially in Britain), reduced to
 simply "tube" or "valve" in everyday parlance, is a device that
 relies on the flow of electric current through a vacuum. Vacuum
 tubes may be used for rectification, amplification, switching, or
 similar processing or creation of electrical signals. Vacuum tubes
 rely on thermionic emission of electrons from a hot filament or
 cathode, that then travel through a vacuum toward the anode
 (commonly called the plate), which is held at a positive voltage
 relative to the cathode. Additional electrodes interposed between
 the cathode and anode can alter the current, giving the tube the
 ability to amplify and switch."

 http://en.wikipedia.org/wiki/**Thyratron<http://en.wikipedia.org/wiki/Thyratron

 "A thyratron is a type of gas filled tube used as a high energy electrical
 switch and controlled rectifier. Triode, tetrode and pentode
 variations of the thyratron have been manufactured in the past,
 though most are of the triode design. Because of the gas fill,
 thyratrons can handle much greater currents than similar hard
 vacuum valves/tubes since the positive ions carry considerable
 current. Gases used include mercury vapor, xenon, neon, and (in
 special high-voltage applications or applications requiring very
 short switching times) hydrogen.[1] Unlike a vacuum tube, a
 thyratron cannot be used to amplify signals linearly."

 Paul Lamar

Vacuum tubes almost went the way of the Dodo, when transistors came out.
The silicone components are so cheap to manufacture and more reliable also.
Some audiophiles seem to prefer the sound from tube systems.  I have not
looked for tubes, but they must be difficult to find now.

Dale Davies


i just got an email about heathkit is just now getting back in buisness.

tom kimsey

Long time no hear from Tom. How's your rotary project coming?

Paul Lamar