FB3 "shutter" control

[h2so4]

Hi guys!

I was wondering about how FB3 controls shutter.
Is the assigned pin (ILDA standard) active for FB3? If so, how can I control the shutter from LiveQuick/LAStudio?

I am planning to put a shutter in my RGB projector. It does not need to be something "safe" eg. for CDRH. I will use my projector only at home and therefore I don't need to certify it. Anyway I would like to put a shutter in it to stop the beam from coming out when lasers are warming up .
Even if the shutter is slow it is good for me: I will use it only to stop the beam for the first minutes after turning the projector on. But I would like to control the shutter with FB3. But even an shutter controlled from an external switch would work...
What should I look for? Medialas actuator? LaserVisuals one?

Thank you very much!!!


Giovanni

[buffo]

Hi Giovanni;

The GM-20 actuator works well for a shutter. You can also use an STP-8 actuator if you want, though it lacks the spring-return feature that the GM-20 has.

The shutter is controlled automatically by the FB3 software. If you have a frame that is being displayed, the shutter pin on the ILDA connector (pin 13) will have +5 volts on it. As soon as you have no frame displayed, the shutter closes automatically.

It's important to remember that the shutter is *automatic*. You can't manually close the shutter from within the software.

Note also that even if you have a show playing, if there is a part of the show where you have no output (all tracks have no frames being displayed), then the shutter will close for that part of the show. It will open up again once you start displaying a frame again. But it's all automatic.

If you want to close the shutter while the lasers are still on, then you will need to add a switch in the line between pin 13 of the ILDA connector and the input to your shutter (either the STP-8 or the GM-20, or whatever else you decide to use). When this switch is closed, the shutter will operate under automatic control via the software on your computer. When you open the switch, the shutter will stay closed even if you have a frame displaying. This will allow you to warm up the lasers without displaying anything.

Adam

[h2so4]

Thanks Buffo for the reply! FB3 will automatically control the shutter as I get it, or will I need a driver? One last thing: where should I look to buy GM20?

Thanks!
Giovanni

[Stuka]

Hey, Giovanni -

Here's a thread you might want to check that discusses a simple driver circuit for GM-20 galvos -

http://www.photonlexicon.com/forums/...light=MechEng3

You might want to check the "Buy, Sell, Trade" section of Photon Lexicon for GM-20's - used ones show up periodically. You might want to start a "wanted to buy" thread and see if anyone here has any available for sale. Or, there's always E-bay...

An advantage to using an STP actuator is they can be driven directly from the shutter signal of the FB3 or other DAC cards. However, as Adam mentioned, they do not gave the spring return to center.

Here's a where I bought mine (but they might be available in the "Buy, Sell, Trade" section of Photon Lexicon as well) :

http://www.laservisuals.com/optact.htm


Good luck with your project!

Randy

[h2so4]

Thank you for the detailed information!
The shutter you bought at Laservisuals is directly controllable by FB3? How much did you pay for it?
About the shutter, as I mentioned, I don't need something particularly quick and safe. Only something to stop the beam...I could even control it with an external, manual switch. At the moment my only concern is money, as I spent almost everything on the other RGB projector components!!!

Thank you very much again!

Giovanni

[buffo]

Hi Giovanni;

As Randy posted above, the STP-8 actuator is very easy to use. There are three connections on it: +12 volts, ground, and signal input. The signal input terminal is the one you need to connect to pin 13 on the ILDA connector.

You'll need a 12 volt power supply inside your projector to supply the STP-8 with power. You'll also want to conenct the ground terminal of that power supply to ILDA ground (pin 25).

I bought a few used STP-8's from Fluff here on PhotonLexicon about a year ago. I think I paid $30 each for them, including shipping. Brand new I think they're less than $50 though.

Adam

[thesk8nmidget]

what is the benefit of the spring on the GM-20 and the lack of on the STP-8?

just faster recoil time?

[buffo]

In the US, if you want to get your projector varianced by the CDRH, you have to have a shutter with a spring-return. So an STP-8 by itself is not adequate. (Of course, you could add your own spring to the shutter arm if you wanted to.)

The GM-20 is the preferred shutter option here in the US, because it has a return spring built-in to the actuator. Unfortunately, you can't drive the GM-20 actuator directly from the +5 volt signal on pin 13 of the ILDA cable. You need a small driver circuit to make it work. (See the link in Randy's post above). Also, GM-20's are more expensive than STP-8's.

Another solution is to simply use a solenoid. You need to find one that is rated for continuous duty, and you'll still need to use a transistor to switch it on and off, but it would still be cheaper than even the STP-8.

As for the speed, that's not a huge issue. The GM-20 is probably the fastest actuator regardless. The spring doesn't have a significant impact on the speed; it's just there to pull the rotor to the closed position in the event of a loss of power. (Personally I think it's a dumb requirement, since on a loss of power the lasers turn off anyway!) I guess it would also protect you if the projector was mounted up-side down, since in that case gravity would tend to pull the shutter open, but who in their right mind would mount a projector like that?

Adam

[thesk8nmidget]

alright well if you added the spring to the STP could you still get it certified?

or does it need to be a brand that comes with the spring from the "factory?"

also how much are the GM's?

[h2so4]

Thank you all very much! You really know a mountain of things!!! About the shutter, I think I'll try the STP-8 because of the price, which seems pretty cheap. For +12V I'll use a computer PSU that will also power the fans in my projector. Thanks for the ILDA ground advice! One more thing: will gravity affect STP-8? Anyway, I don't think I will ever mount my projector up-side down, so it wouldn't matter...As for the speed, will STP-8 be fast enough to respond to FB3 signal? I only fear it didn't open fast enough...

Thank you very much guys!!!

Giovanni