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Randy Moe
8-Feb-2014, 23:29
My Packard shutter has a failed 120 volt solenoid. I need to find a cheap and simple replacement. I don't have a piston and bulb setup for it and my hands often fail with Packard bulb actuation.

I am looking for something modern and cheap. Looks like I only need 5 to 6 mm of pull with spring return. I have considered Radio Control model servos and all that entails, but that is pretty complicated for a simple linear solenoid replacement.

Has anybody found an available replacement? Amazon sells these in 24 volt for $15, but I prefer to hear of successful conversions. Lower voltage would be nice.

Since it is going on a stationary studio camera, a wired bulky solution is fine.

The worn out solenoid I removed has no source info and is big, 1.5x1x4". Overkill that doesn't work. I can use any voltage. Not 220...

The shutter control lever moves easily, heck, slight air pressure opens these ingenious devices.

I also will be adding a microswitch for flash sync, that's the easy part. Made in Japan parts delivered for $3. How do they do that?

110109

C. D. Keth
9-Feb-2014, 00:09
thesolenoidcompany.com (http://www.thesolenoidcompany.com) almost certainly has something that will work.

Randy Moe
9-Feb-2014, 00:32
They do have many options and I learned a permanent magnet latching solenoid will stay open without continuous power. Many solenoids I have seen elsewhere tonight have 1 minute pulled in duty cycles which would not be enough for my slow focusing technique.

But ordering one from UK may not be cheap.

Thanks for the link!


thesolenoidcompany.com (http://www.thesolenoidcompany.com) almost certainly has something that will work.

Jac@stafford.net
9-Feb-2014, 06:50
I have used Ledex solenoids, usually the rotor type. Making the offset disc to convert to push or pull is trivial.

http://www.ledex.com/

Amedeus
9-Feb-2014, 10:58
Randy,

I second the idea to use a rotary solenoid from Ledex, smaller footprint and easy to work with.

As for duty cycle, this is what I do with my electric Packard shutters.

I've converted all of them to 24 volt DC if they were not already working on that voltage. Some of them are rotary, others linear plungers with a return spring.

I actuate them with a pulse of 48 volt and keep them open with a voltage of 12 volt. The pulse improves opening time a bit and the lower voltage to keep the solenoid in the open position reduces the power through the solenoid 4-fold and minimizing the release time a tiny fraction ;-)

The pulse is generated by charging a capacitor through a resistor up to 48 volt coming from a power supply. The charging resistor is 3 times the value of the solenoid wire resistance in my implementations. The capacitor is a 63 volt electrolytic cap, I've used 220uF to 1000uF depending on the size (resistance) of the solenoid.

The solenoid is connected to the capacitor through a single pole switch. Upon contact the capacitor discharges the full 48 volt in a few milliseconds through the solenoid which opens and for most solenoids 1/2 rated voltage is sufficient to keep the solenoid fully open.

YMMV

Jac@stafford.net
9-Feb-2014, 11:45
I couldn't make what Amedeus described if my life depended on it. :(

But, for the last Ledex solenoid driven shutter I made I kept the shutter open for focusing using a straight rod to the actuator and simply locked it in place, and released it before exposure. Simple, not sophisticated. Might have a photo of it if you like.

Randy Moe
9-Feb-2014, 14:40
So easy to say, 'Yes please Jac', I would love a photo of it.

Thanks!


I couldn't make what Amedeus described if my life depended on it. :(

But, for the last Ledex solenoid driven shutter I made I kept the shutter open for focusing using a straight rod to the actuator and simply locked it in place, and released it before exposure. Simple, not sophisticated. Might have a photo of it if you like.

Randy Moe
9-Feb-2014, 14:55
Got it. Good ideas all around. The existing 117 volt solenoid also has a resistor and capacitor wired to it, for similar purposes, I think.

Magnetic latching seems to be a good idea. I am also looking into RC model servos like this. Not sure yet how to actuate them. I guess just hit it with juice. The opening speed is slow at 0.17 sec at 5 vdc, which will give me a fast shutter speed of ~1/3 second, with long exposures of any length. Cost is good. http://www.amazon.com/Sunkee-Tower-MG995-13kg55g-Torque/dp/B00D402FY2/ref=sr_1_2?ie=UTF8&qid=1391982620&sr=8-2&keywords=rc+boat+servo


Randy,

I second the idea to use a rotary solenoid from Ledex, smaller footprint and easy to work with.

As for duty cycle, this is what I do with my electric Packard shutters.

I've converted all of them to 24 volt DC if they were not already working on that voltage. Some of them are rotary, others linear plungers with a return spring.

I actuate them with a pulse of 48 volt and keep them open with a voltage of 12 volt. The pulse improves opening time a bit and the lower voltage to keep the solenoid in the open position reduces the power through the solenoid 4-fold and minimizing the release time a tiny fraction ;-)

The pulse is generated by charging a capacitor through a resistor up to 48 volt coming from a power supply. The charging resistor is 3 times the value of the solenoid wire resistance in my implementations. The capacitor is a 63 volt electrolytic cap, I've used 220uF to 1000uF depending on the size (resistance) of the solenoid.

The solenoid is connected to the capacitor through a single pole switch. Upon contact the capacitor discharges the full 48 volt in a few milliseconds through the solenoid which opens and for most solenoids 1/2 rated voltage is sufficient to keep the solenoid fully open.

YMMV

Jac@stafford.net
9-Feb-2014, 16:20
So easy to say, 'Yes please Jac', I would love a photo of it.

Thanks!

I must hook-up an old hard drive to find it, and I will tomorrow. In words, what I used is a model aircraft mech (those designers are amazing) and a simple hardware latch to hold it open.

I used it for a wide-angle 8x10 Sky Camera I built long ago.

Later!

Randy Moe
9-Feb-2014, 16:38
Sounds cool!


I must hook-up an old hard drive to find it, and I will tomorrow. In words, what I used is a model aircraft mech (those designers are amazing) and a simple hardware latch to hold it open.

I used it for a wide-angle 8x10 Sky Camera I built long ago.

Later!

Carsten Wolff
10-Feb-2014, 07:45
I went with a 485:1-geared 12V micro-motor (Faulhaber) which I picked up on the bay for 12 quid, (in my case to actuate a Prontor #1 on a 5x7" underwater camera). Works a charm and doesn't draw current between actuations, but I don't do timed exposures via the triggering mechanism.

Jac@stafford.net
10-Feb-2014, 08:56
So easy to say, 'Yes please Jac', I would love a photo of it.

Thanks!

The shutter is from an 8x10" research camera I made into a 90 degree angle camera for pictures of the stars. This shutter fit between the cells of a Metrogon lens, of which I have several, but no more shutters!

110216


110217

And the camera in operating position.

http://www.digoliardi.net/skc/skc1.jpg

I have many more pictures and can put up the whole web page if you like.

Gosh, I wish I had not sold that camera.

Randy Moe
10-Feb-2014, 11:17
Very interesting! Love that camera, all shiny and sleek.

The manual lever for the shutter is a good idea.

A website on your camera may be a good idea to show the whippersnappers how it was done.

Not sure where I'm going yet, so many projects...


The shutter is from an 8x10" research camera I made into a 90 degree angle camera for pictures of the stars. This shutter fit between the cells of a Metrogon lens, of which I have several, but no more shutters!

110216


110217

And the camera in operating position.

http://www.digoliardi.net/skc/skc1.jpg

I have many more pictures and can put up the whole web page if you like.

Gosh, I wish I had not sold that camera.

Randy Moe
10-Feb-2014, 11:21
Thanks Carsten, and I see there are many of this type on eBay.



I went with a 485:1-geared 12V micro-motor (Faulhaber) which I picked up on the bay for 12 quid, (in my case to actuate a Prontor #1 on a 5x7" underwater camera). Works a charm and doesn't draw current between actuations, but I don't do timed exposures via the triggering mechanism.

Randy Moe
12-Feb-2014, 01:18
Robot parts, duh!

Jac@stafford.net
12-Feb-2014, 10:32
Robot parts, duh!

http://www.robotshop.com/

My favorite source: http://www.servocity.com/

Randy Moe
12-Feb-2014, 10:57
I have not built a robotic device in many years, long before the Internet. Amazing stuff for cheap. This will be the way to run my Packard and sync.

I'm slow sometimes, but finally the LED lit up.

Thanks everyone for all the old school recommendations.

Is it LF if I run a shutter with a micro computer? That's rhetorical. Does not apply on this forum, but what would APUG say?


http://www.robotshop.com/

My favorite source: http://www.servocity.com/

Randy Moe
12-Feb-2014, 14:13
If you are interested watch this simple video demo of servo testing and programing.

https://www.youtube.com/watch?v=AqToEWmTVXA

Harold_4074
12-Feb-2014, 17:41
Little known fact: a brush-type DC motor operated under constant current becomes a torque motor.

So a hobby-shop 12VDC motor fed from a current source, with a piece of dial cord wrapped on the shaft, can be used to create linear motion. Loop the cord and put in a small spring to keep it snug, and you have a reversible linear drive with a zero-power position at each end of the travel. The same boost/hold idea can be used by simply using the current source to charge a capacitor during the idle time---the capacitor will deliver a real current surge (briefly) when the switch closes.

Randy Moe
12-Feb-2014, 18:31
I saw a video with a home wound motor doing just that.

I am hoping I can achieve variable shutter speeds with a little more than the controler in the video. The controller and servo cost $30.


Little known fact: a brush-type DC motor operated under constant current becomes a torque motor.

So a hobby-shop 12VDC motor fed from a current source, with a piece of dial cord wrapped on the shaft, can be used to create linear motion. Loop the cord and put in a small spring to keep it snug, and you have a reversible linear drive with a zero-power position at each end of the travel. The same boost/hold idea can be used by simply using the current source to charge a capacitor during the idle time---the capacitor will deliver a real current surge (briefly) when the switch closes.

Randy Moe
23-Feb-2014, 14:28
Still working on this.

Using RC servos I have very reliable 1/2 second shutter speed with adjustable flash sync.

I was hoping for faster, but not happening with this setup. however the flash will freeze motion, obviously...

I will install it and use it for studio work.