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bht2010
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Join Date: Dec 2010
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12v Controlled Lens Covers

08/21/2012 8:44 PM

Hi all, am after some assistance to design a system of covering projector outputs.

I have four projectors that run simultaneously, to switch between each one I need to physically block the output from the other three, I have the control system and have 4 individual switchable 12V sources to operate some form of lens cover.

Its just the physical movement of a cover I need help with.

I was thinking along the lines of 4 linear actuators but these dont seem to retract when 12v is removed( has to be reversed polarity to pull the cover away),

Any ideas or assistance would be greatly appreciated.

Cheers bht2010

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SolarEagle
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#1

Re: 12v Controlled Lens Covers

08/21/2012 9:38 PM

How fast do the doors have to open and close? How do they open? What is the size of the doors? You could use a hydraulic setup....sounds pricey...I would spring mount one way...

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SolarEagle
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#2
In reply to #1

Re: 12v Controlled Lens Covers

08/21/2012 9:55 PM

Solenoids would probably work better....with some sort of rc 4 channel controller....

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bht2010
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#3
In reply to #1

Re: 12v Controlled Lens Covers

08/21/2012 9:56 PM

As long as they react within a second or two that would be fine. I was looking at car door lock actuators but they wouldnt retract and also didnt have the length of travel required to cover the lens,... you could be onto something with the spring mount to retract, might be able to put a pivot point to increase travel distance and put a spring on to return it to an open position..

The covers are approx 6" x 4" squares of black flet covered plastic to absorb as much light as possible

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SolarEagle
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#5
In reply to #3

Re: 12v Controlled Lens Covers

08/22/2012 12:00 AM

Perhaps something like this.....

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bht2010
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#6
In reply to #5

Re: 12v Controlled Lens Covers

08/22/2012 12:08 AM

Wholly giant meccano sets batman!!

Yeah pretty well what I had in mind, not too sure how I can mount it all but that should work with a car actuator , your addition of a return spring and a bit of luck...

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SolarEagle
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#9
In reply to #5

Re: 12v Controlled Lens Covers

08/22/2012 9:37 AM

or this...

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K_Fry
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#10
In reply to #9

Re: 12v Controlled Lens Covers

08/22/2012 1:37 PM

I agree. A spring-return solenoid would work well. (The actuator connection point on the door could be raised, and the linkage could be straight rather than curved. Then the initial leverage would be better and the assembly would have a better stiffness-to-weight ratio. Yes, I understand this is just a sketch. )

The door may have enough air resistance to damp the movement, preventing loud noises. If not, a pneumatic damper cylinder could be added alongside the solenoid.

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SolarEagle
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#12
In reply to #10

Re: 12v Controlled Lens Covers

08/22/2012 10:58 PM

Well if it is mounted vertically, gravity should close the door ok.....I would add some felt spots around the door for dampening....

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bigg
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#4

Re: 12v Controlled Lens Covers

08/21/2012 10:35 PM

Maybe you could use a solenoid? Here's one source (usual disclaimers) www.zorotools.com You have to specify AC or DC and you may have to adapt some dampening - they tend to be quick-acting.
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james denoil4
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#7

Re: 12v Controlled Lens Covers

08/22/2012 2:38 AM

thanks nice post
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Usbport
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#8

Re: 12v Controlled Lens Covers

08/22/2012 8:06 AM

I once used a rotary solenoid for a shutter to block a HeNe laser beam. Rotary solenoids can be extremely fast-acting and are very reliable, so they can actuate millions of times without much likelihood of a problem. You can easily machine a shutter out of black delrin or aluminum and attach it to the shaft. Depending on how big the shutter is, you might need to make sure it is well-balanced for rotary motion.

If possible, get a solenoid with 2 flats on the shaft 90 degrees apart and use 2 set screws to hold the shutter in place. You should be able to find ones spring-loaded for return when power is removed. Here is a link to some rotary solenoids.

http://w2s.solenoids.com/ledx/ds/LXEZR/LXEZR2e.lasso?pcode=L208

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bht2010
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#11

Re: 12v Controlled Lens Covers

08/22/2012 7:01 PM

Thanks Usbport, hadnt thought of rotary solenoid, found this one, looks like it will be perfect.

Many thanks all, will let you know how it all pans out..

Thanks BHT2010

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Nigh
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#13

Re: 12v Controlled Lens Covers

08/23/2012 5:00 AM

You could use shutters, either mechanical or electronic. Might be too expensive though.

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