🚀 go-pugleaf

In article <1992Oct6.151125.15989@cis.ohio-state.edu> fontana@dogwood.cis.ohio-state.edu (Mark Fontana) writes:
>What I'd like to do is position these tiny flashes all around the room,
>then fire the first flash manually.  The other flash circuits would detect
>this main flash and delay for a preset interval before firing. 

>I'm looking for advice on how to wire these up.  I figure I can
>just use an RC circuit on each one to get the desired delay.  The two
>main problems are:
>
>     2) discharging the flash capacitor (200uF?) without frying
>        components left and right.  Are there SCR's that can handle this
>        directly, or should I plan on using little relays?
>

No real help on the 1st question (triggering mechanisms) but you reallly
don't have a problem w/ the second... You don't need to discharge the
Cap through any components... the Cap discharges through the tube, and
is _always_ connected directly across the tube.  Now it doesn't 
discharge or leak across the tube when it is not firing because the
gas in the tube in a relatively good insulator.  What _does_ allow
it to discharge is ionization of the gas in the flash-tube.  Notice
that there are 3 wires going to the tube?  2 of those should protrude
through the envelope at the ends, and terminate in some short 
(usually dark) pegs.  If you measure the voltage on them when the
flash is fully charged, you'll find that they are direcly connected
to the Cap.  The third wire should be connected to a bit of foil
along the surface of the tube, or perhaps a thin wire wrapped around
the tube.  This will run almost the whole length of the tube, and
is the trigger for the flash.  you'll find it to be isolated when
the flash is charged.  Now to discharge the flash, what needs to
happen is the gas be ionized, which lets current flow, which ionizes
more gas, etc, and POP you get a flash.  That initial ionization
is caused by application of voltage to this third "mystery" wire.
Since the current flow through the trigger wire is low (only
enough to start ionization) you should be able to use just about
any switching mechanism that won't break under the full voltage
of the flash.

Hope that helps

Will Ray
ray@cis.ohio-state.edu