Is it a Diode, or Zener or what

[PerdioPal]

I remember in the 70's Practical Wireless did a capacitor discharge ignition project. They had the forethought to include a switch to revert to Kettering (points and coil) in case of failure. That's faith in the design!

[`FRANK.C]

I guess the Fencers must be like an electronic flash gun circuit.

Yes the battery electronic ones are similar. The battery is usually 7.5 or 9 volt. A simple oscillator and transformer arrangement produces a HT in the region of 300 to 400 volts.
The higher the HT the lower the turns ratio of the output transformer. Which helps to keep the output impedance low.

Frank

[BusyBee]

I remember in the 70's Practical Wireless did a capacitor discharge ignition project.  They had the forethought to include a switch to revert to Kettering (points and coil) in case of failure.  That's faith in the design!

I have a Maplin design which I imagine was very similar.

Tracy

[Ed_Dinning]

Hi Folks, the WW electronic ignition was a good design that worked well, but was sensitive to mis-triggering and loss of scr sensitivity (always a difficult design decision).
I published a modification in the letters section a few months later that used opto-couplers (an odd device in those days) that overcame these problems.
I ran one of these units for several years on various cars. they gave a small improvement in consumption as well as reducing wear on points and hence better timing stability. I usually increased the plug gap to 30 thou as well


Ed