Ilex electronic shutter question(s)

[Bob Fowler]

I've been seeing a lot of the Ilex #3 electronic shutters on the big auction site. The vast majority do not come with the control box and are selling for very little money.

My question(s): Does anyone know the correct control voltage to the solenoid? and: What were the fastest speeds that these were physically capable of?

I have a couple of lenses in #3 Acme Synchro shutters (the set & release type, not self cocking). One of them is marked up to 1/200th and the other (a newer model) to 1/150th - Both really top out at about 1/125th on my tester.

I went ahead and did a "buy-it-now" on one for $25.00 (including some unmarked glass) as a "let's see what this puppy can do" project. Making the timing circuit should be very easy, but I'd like to know the proper control voltage so I don't fry the solenoid.

Thanks in advance for any help ya'll can throw my way.

[Ernest Purdum]

The nominal voltage rating is 48VDC. Some Melles Griot (successor to Ilex) shutters operated on lower voltages, but as far as I have been able to find out, the Ilex are all high voltage. In operation, a pulse of 192VDC for a 3-5 millisecond duration is applied to open the blades quickly, then a holding voltage of 24VDC keeps the shutter open for the duration of the exposure. The shortest exposure is 1/125 second. The current used is indicated as 4 milliamp maximum. I suppose that refers to the holding voltage, not the pulse.



Ilex (but not Melles Griot) called their controller a "speedcomputer". There seem to have been several versions.



If you send me your mailing address, I'll send you some Melles Griot information on the subject.

[Ralph Barker]

Bob - I've been wondering about those, too. Sounds like a fun project. Let us know how it comes out.

BTW, I have a backpack frame that holds 4 car batteries, if you're interested. ;-)

[Conrad Hoffman]

My first job was working for the company that made these back in the '70s. I don't remember anything specific about them, but do remember that the timing circuit was a weird discrete affair using a neon bulb as the turn-off trigger at about 80V, and another neon bulb that shined on the first one so the trigger point would be stable (they're light sensitive). The thing was completely non-linear and not too predictable, so all the timing resistors on the speed switch were selected for each unit. We had a big hand made resistor box with a selection switch for each shutter speed. Today a 555 timer circuit would do the same thing far better and the same way every time. I'll assume that early circuit was abandoned as quickly as possible!

[Bob Fowler]

Ernest - Thanks, I'll send you my snail mail via email. I assume that they 192v pulse was just a capacitor being discharged. The circuit should be real easy to work out.

Ralph - I'll keep ya'll posted, and no - I ain't luggin' car batteries! :-)

Conrad - A 555 is just what I had in mind.

Everybody - When I get the whole shebang working reliably, I'll publish a web page with the project details (including circuit diagrams & pix).

Thanks for your help!!!