D.S. Copal Magnetic Shutter

[cyberjunkie]

Hi.
I just found on Ebay this Copal shutter:
http://cgi.ebay.com/ws/eBayISAPI.dll...m=120638087259
I have a shutter at home that t looks exactly the same!
I removed it from a very big reprocamera lensboard, with diaphragm scales and a huge bajonet attachment to exchange the lens.
Even the plug (with three pins) is the same, and on the shutter body there is the same engraving: D.S. Copal.
I am attaching a picture if the reader is too lazy to have a look on Ebay:-)

At first i didn't even know if it was for AC or DC, then i figured out that originally it should have taken the juice from a power adapter, so DC was more likely.
From the text of the auction i get that it needs 24V, while my guess was for 12V.
The simplest way to use it should be to find two rechargeable batteries with 12V output, connect them in series to get 24V, and use one of those pushbuttons used in electronics to control the length of the power burst with your thumb.
With a little of exercise, it should be as easy (or maybe as difficult) as operating those Packard shutter that don't come with the "instant" pin.
I can't foresee any possible problem, because the the rod that transmits the movement to the shutter blades has a spring, so when the electricity is cut the shutter should close by itself. That's theory, i'd like to get some input from somebody who actually did some experiment with this type of shutters.

The best thing would be to find some kind of DIY electronic project that would allow to control the timings.
It should be fairly simple for somebody who knows a little about electronic circuits, but i haven't found anything useful online.
Recently i have seen for sale a control box for Ilex Electronic Shutters, it's the first time i have seen such a device sold alone, but i don't have the slightest idea about its functionality and in which way electronic shutters made by Ilex were controlled.
In the end it didn't sell for too much, but my budget is too tight, so i refrained from buying something that MIGHT be useful (and that would require a 110V to 220V AC converter).
What's for sure: the D.S. Copal electromagnetic shutter could be a true lifesaver, for those (like me!) who own cheap process lenses in barrel... if there is some way to operate the shutter in a controlled and repeatable way

I have read somewhere that some electric shutters open and close the blades in rapid succession, when powered. That would make the manual release of the shutter a difficult task, cause only one time would be available, and the pushbutton should be operated very fast, to avoid multiple exposure!
Any first-hand experience with the D.S. Copal?

have fun

CJ

[domaz]

Making controllers for them is a little tricky because you have to provide an initial burst of high voltage power and then a lower voltage to hold the shutter open. This link details construction of a controller.

[Jason Greenberg Motamedi]

I have the same shutter, also pulled off a reprocamera. I showed it to my brother who is an electronic engineer, and he said that he could probably figure out how to run it and build a controller, but that it might take a while. Let me know if you figure it out, and if he ever gets to it I will let you know.

[BetterSense]

Making a controller would be a piece of cake. I would probably just use some small SLA batteries, some electrolytic caps, a darlington transistor or two, and a microcontroller.

[Ernest Purdum]

I don't think you can count on the solenoid voltage. I am away from home and don't have the info at hand, but my recollection is that they were available at different working voltages and perrhaps even either AC or DC.

I would try to find someone with a variable power supply to try it out.

The Ilex (and Compur, I think) high voltage opening and lower voltage holding arrangement is a way of reducing battery size for out door use. The DS Copal shutters (and similar shutters made by Prontor) were mostly used indoors.

[cyberjunkie]

I think that a test with a variable voltage power supply is the only way to go.
That way it is possible to find out which voltage opens the shutter, and at which (lower) voltage it closes.
I have contacted the talented technician who published on his personal site (http://www.chemie.unibas.ch/~holder/shutter/index.html) a project for controlling a Melles Griot electronic shutter (good also for Ilex).
He promptly answered my request for help, and gently provided a few basic advices.
The project he made is based on an integrate that isn't available anymore, other way it could have worked with some minor modification.
I guess i could be more than happy with a less sophisticated device, so a simpler solution could be the way to go.
I was given the advice to use a NE555 IC, a timer that could be used with a rather simple circuit. I have found some documentation on Wikipedia:
http://www.kpsec.freeuk.com/555timer.htm#monostable
The link refers to the "monostable" operation, that should be exactly what's requested to operate a shutter.
I have no experience at all about electronics, i even forgot the very little general informations i did learn at school. So if somebody with similar needs, and with some familiarity with circuits, can provide some help, it would be great.
Even better: a simple circuit, with a reference to all needed components, that could be made by any technician with a minimum of expertise.

I have seen many electronic shutters for sale on auction sites or forums (most of them sold without controller), and a few posts asking for some simple solution, so i'm not the only one looking for some help...


have fun

CJ

[Jack Dahlgren]

I think that a test with a variable voltage power supply is the only way to go.
That way it is possible to find out which voltage opens the shutter, and at which (lower) voltage it closes.
I have contacted the talented technician who published on his personal site (http://www.chemie.unibas.ch/~holder/shutter/index.html) a project for controlling a Melles Griot electronic shutter (good also for Ilex).
He promptly answered my request for help, and gently provided a few basic advices.
The project he made is based on an integrate that isn't available anymore, other way it could have worked with some minor modification.
I guess i could be more than happy with a less sophisticated device, so a simpler solution could be the way to go.
I was given the advice to use a NE555 IC, a timer that could be used with a rather simple circuit. I have found some documentation on Wikipedia:
http://www.kpsec.freeuk.com/555timer.htm#monostable
The link refers to the "monostable" operation, that should be exactly what's requested to operate a shutter.
I have no experience at all about electronics, i even forgot the very little general informations i did learn at school. So if somebody with similar needs, and with some familiarity with circuits, can provide some help, it would be great.
Even better: a simple circuit, with a reference to all needed components, that could be made by any technician with a minimum of expertise.

I have seen many electronic shutters for sale on auction sites or forums (most of them sold without controller), and a few posts asking for some simple solution, so i'm not the only one looking for some help...


have fun

CJ

There are a number of "pre-packaged" microcontrollers out there right now which include a microcontroller, power regulation, and programming interface and software. The Arduino is a good example.

http://www.arduino.cc/

Something like that is going to be a lot more flexible than wiring up a 555 timer and will be programmable to do a bunch of other things.

Using two of the ports, two transistors and two diodes you can easily trigger a high voltage pulse and then a lower voltage holding voltage of almost any duration you like. The circuit on the right side of the diagram on the site you are looking at would be what you would hook up to the microcontroller.

[BetterSense]

555 timer is one (old) way to do it. IMO, that's the way you would do it back in the '90s before good microcontrollers were cheap. For things like this, I use a microcontroller nowadays. I used Arduino for all my digital light meters and densitometers. Sparkfun.com is a good source for Arduino stuff.

[cyberjunkie]

555 timer is one (old) way to do it.

I use a microcontroller nowadays. I used Arduino for all my digital light meters and densitometers. Sparkfun.com is a good source for Arduino stuff.

I have already found references about Arduino and other programmable microcontrollers, that would be perfectly capable to do what i need, and much more.
Unfortunately i am in no way a programmer.
What's nice about Arduino is that it's open, and that there is a vast community of users.
My capabilities are very limited, so the only way out would be a stroke of luck, finding the solution already "pre-cooked" by somebody else!
What needs to be done is quite simple, even if you need a sync-flash (which i do not), so it should be a simple task, if somebody is a little experienced. Maybe there is even a chance that one of the forum user would choose tha tackle this problem, producing a ready-to-make project... who knows

have fun

CJ

[BetterSense]

A shutter-driving program should very simple to write. I could do it on lunch. I would be more than willing to write code for you, provided it stays open source. In fact, if this were a popular application we would write an Arduino library and submit it for others to use and modify. That's why I prefer using microcontrollers; the sky is the limit as long as it's open source. With some trial-and-error, a flash sync feature could be implemented handily, or intervalometer software, or a remote trigger, or...