5823 optical trigger? tube

[Opcom]

Taking apart a quite old photoflash slave unit to get the trigger transformer for my laser, I found a very interesting tube inside.

The tube is a 5823. It is 7-pin miniature. It is mounted behind a phenolic disk upon which the flashlamp is mounted. the disk has a few small holes to admit light to strike the tube's photocathode(?). The element I am calling the photocathode looks just like the photocathode in an old "electric eye" phototube. The "anode" on this tube however, looks heavy duty and is shielded by a nonconducting-looking cylinder of some kind, except at its end.

The tube is in series with a 0.1uF 400V orange drop and the trigger transformer primary. It's obvious this is a switch to dump the cap into the trigger transformer to produce the HV pulse necessary to initiate the flashlamp discharge.

I did not find the specs for this interesting tube and would like to experiment. Does anyone have a line on the spec or application?

[Pete, WA2CWA]

Easy to find:

http://tubedata.milbert.com/sheets/137/5/5823.pdf

[Opcom]

Thanks! That makes the whole thing even more mysterious. Other voltages such as the grid voltage must have come from the power pack. I'd like to see the tube ionize anyway since the anode is a semicircle. 20uS ionization time, snazzy!

Maybe before I disassemble any of the circuit, I'll try it out. No reason the tube and circuit couldn't be used as intended. The laser pump is just a flashlamp too and I did not design the trigger for it yet so why invent the wheel?

[Rob K2CU]

Sounds like this is the photo detector/trigger driver that fires when it "sees" the flash from a "Master" photo flash unit. You might not be able to look at it if ambient light makes it conduct. Then again, if you had it in a darkened room, the primary flash would probably temporarily blind you so you couldn't see it anyway.  Yet another neat special purpose vacuum tube. You could use it anywhere that modern day circuits use photo cells or photo diodes. 20uS sounds faster than photo cells but much slower than photo diodes.

[Opcom]

It seems to be billed as a thyratron-like tube, grid-tiggerable. I could go that route. or, perhaps use a small 100mW laser to try triggering it.