DIY electric projector screen

[jdreier]

I am going to make my own HT projector screen with electric remote control roll up and down.

Requirements:
Aspect Ratio: 16:9
Width: About 9 feet
Material: White speaker grill cloth (To allow my speakers to transmit sound from behind the screen.) I will sew a black border around it.

Any way, as I am creating my control circuit I realized I do not know what the 12 volt trigger from most pre-amps is.

Can some one tell me...
When a 12 V trigger is turned on does it go to 12 V and stay at 12 V or is it just a 12 V pulse that goes back to 0 Volts after a few milliseconds?

Thanks

James

[ThomasW]

Depends on the device, some need to see a constant voltage or they shut off. Others use a pulse to toggle the device on and off.

[Kevin P]

Pre-amps and amps use a constant 12V signal. The signal activates a relay in the amp. When the pre-amp is shut off, the 12V trigger shuts off, causing the relay in the amp to shut off as well.

[Bent]

the 12 volt ouput trigger in the Panny '700 "may" not drive a a screen solenoid - they are apparently limited as to how much curent the can provide and may require an auxilliary relaY.

[cjd]

the 12 volt ouput trigger in the Panny '700 "may" not drive a a screen solenoid - they are apparently limited as to how much curent the can provide and may require an auxilliary relaY.

Goodness, yes. The trigger shoudl *only* ever be used as a trigger, and not as a current source for some specific action. In this case, you're going to need a timer anyhow, and it's going to need a voltage to roll the screen back up after you power down the amp, so I think it may be a given, regardless.

C

[ThomasW]

Pre-amps and amps use a constant 12V signal

Apparently some preamps are dyslexic.......:wink:

As a result my Ayre V5 (power amp) can be 'programmed' to function with either constant or pulse depending on the nature of the triggering source.

[Dennis H]

I can't help you with the electronics but I'm worried that grill cloth would be too stretchy for a rollup screen. For an acoustically transparent rollup, the commercial guys use a stiff fabric where the "threads" are PVC coated fiberglass and there is enough spacing to let the sound through. The stuff is similar to some commercial rollup blinds. Vutec and Draper will sell their woven acoustical material and there are many variations of the stuff available if you live in a big city. Here's a thread at AVS. It starts out discussing the Vutec in a fixed frame but gets into an errrr.... interesting argument about fabrics and how proprietary they are later on.

http://www.avsforum.com/avs-vb/showthread.php?t=557165

[cjd]

Oh my, I missed that part!

Speaker grill-cloth is going to be quite visually transparent as well as being transparent to sound! Not to mention the stretchy thing.

C

[jdreier]

Thanks for all the info so far

I come back from camping and, shazam, all this information is at my fingertips. Thank you everyone for your responses so far.

I guess I will wait to get my preamp and just measure the output of the trigger.

Dennis, you bring up a much more critical concern in my design.

I am only about 1/5 the way through the thread at avsforum it is very interesting and helpful.

Has anyone here done a DIY roll up screen with acoustic transparency here at HTguide? If so what material did you use?