I am planning to rig up a battery box to power my Focuspot and to trigger the shutter through a Heiland solenoid. I'll be using a Norman electronic flash, so I won't have the batteries from the old flash units.

My question is, what voltage is the Heiland solenoid supposed to use? I've seen flash units with 2, 3 and 4 cells, so it would appear voltage is not critical. I tested my unit by touching the contacts to a 9v transistor radio battery and it worked - and touched it to leads from a 2-cell battery box and it worked. I might want to use the 9v because I've found a 9-24v LED bulb that will fit in the focuspot.

Will I cause any trouble by not using the right voltage - if there is a right voltage?

The Graflex Solenoid manual says the solenoid is tripped with the 3 cell synchronizer so that would make it 4.5V and the Graflite user manual says that the batteries must supply at least 7 amps of current.

A solenoid is a current dependent device and the current capacity of the power source is more important than the voltage. Too high a voltage may damage a solenoid as will too low a voltage or holding it engaged with the pull down current for an extended period of time.

E(voltage)=I(current)*R(resistance)
I=E/R
R=E/I

At 4.5V and 7 amps the coil resistance of a solenoid would be .64 ohms.

That's more amps than I anticipated. It looks like the 9v is out, and I'll have to revise my plans.
Thanks.

Don't give up yet.
2- 1 ohm resistors connected in parallel = .5 ohms.
.5 ohms in series with a solenoid's .64 ohms resistance = 1.14 ohms.
9V/1.14=7.89
New batteries read about 1.65V so three of them will be 4.95V
4.95/.64=7.73

http://www.mouser.com/ProductDetail/TE-Connectivity-Holsworthy/CBT25J1R0/?qs=sGAEpiMZZMuDPtTs5Gda2%2fwGMz2hofsMiGYdifYzSiI%3d

Connect the resistors in the negative lead from the power source to the solenoid and don't worry about it.

power supply-----resistors side by side----solenoid.