Spark (pulse) generators for HT igniters - UK Vintage Radio Repair and Restoration Discussion Forum

phildil · 29th Nov 2022, 11:00 pm

hi all

One of the components in an arc lamp igniter (in this case for cinema film projectors) is a HT spark or pulse generator like those shown in the photos (the one on the right in the two-shot is the duff one). These eventually wear out and I've just replaced one of ours by scavenging it from a 50 year old disused igniter unit. My question is, are these components still readily available new, or is there a modern equivalent?

cheers
phil

kalee20 · 30th Nov 2022, 11:08 pm

I guess it's a spark gap - a capacitor is charged from a mains transformer and diode (or possibly a low-voltage flyback converter) up to the breakdown voltage of the spark gap (around 1kV), and then discharges rapidly via the spark gap into a low-resistance winding of an impulse transformer to step up to several kV at a fairly low impedance, in turn to cause breakdown in your high-pressure Xenon lamp and initiate an arc.

Yes they're still available - the company I work for uses them in a similar manner, as part of jet engine ignition units!

A quick Google search for 'E2V spark gap' (used to be English Electric Valve) throws up several hits.

phildil · 1st Dec 2022, 1:48 pm

Yes - that's it exactly. thanks.

They're certainly not cheap though !! Carry on scrounging, I think.

cheers, Phil

29th Nov 2022, 11:00 pm	#1
phildil Pentode Join Date: Sep 2014 Location: London, UK. Posts: 115	Spark (pulse) generators for HT igniters hi all One of the components in an arc lamp igniter (in this case for cinema film projectors) is a HT spark or pulse generator like those shown in the photos (the one on the right in the two-shot is the duff one). These eventually wear out and I've just replaced one of ours by scavenging it from a 50 year old disused igniter unit. My question is, are these components still readily available new, or is there a modern equivalent? cheers phil Attached Thumbnails

30th Nov 2022, 11:08 pm	#2
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,082	Re: Spark (pulse) generators for HT igniters I guess it's a spark gap - a capacitor is charged from a mains transformer and diode (or possibly a low-voltage flyback converter) up to the breakdown voltage of the spark gap (around 1kV), and then discharges rapidly via the spark gap into a low-resistance winding of an impulse transformer to step up to several kV at a fairly low impedance, in turn to cause breakdown in your high-pressure Xenon lamp and initiate an arc. Yes they're still available - the company I work for uses them in a similar manner, as part of jet engine ignition units! A quick Google search for 'E2V spark gap' (used to be English Electric Valve) throws up several hits.

1st Dec 2022, 1:48 pm	#3
phildil Pentode Join Date: Sep 2014 Location: London, UK. Posts: 115	Re: Spark (pulse) generators for HT igniters Yes - that's it exactly. thanks. They're certainly not cheap though !! Carry on scrounging, I think. cheers, Phil