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ATWindsor's Avatar ATWindsor
12:44 PM Liked: 10
post #1 of 8
12-10-2013 | Posts: 350
Joined: May 2004
A 12V-signal via minijack from the projector to control a motorized screen is pretty normal. Almost all motors can be controlled by relays, so a relay which is controlled by a 12V-signal should be something that is highly useful. But I haven't found it, does anybody have a tip to where i can get something like this?
jpmst3's Avatar jpmst3
01:08 PM Liked: 215
post #2 of 8
12-10-2013 | Posts: 8,262
Joined: Dec 2005
Quote:
Originally Posted by ATWindsor View Post

A 12V-signal via minijack from the projector to control a motorized screen is pretty normal. Almost all motors can be controlled by relays, so a relay which is controlled by a 12V-signal should be something that is highly useful. But I haven't found it, does anybody have a tip to where i can get something like this?

It depends on how you want to implement it.

You just use a power sensing strip or an actual relay.
Try this: https://www.sparkfun.com/tutorials/119

Or a Niles box http://www.nilesaudio.com/product_detail.php?recordID=120Volt%20AC%20Power%20Switching%20Systems&categoryID=Switching%20Systems&catcdID=10

I have used the AC-3 for many years.
ATWindsor's Avatar ATWindsor
01:15 PM Liked: 10
post #3 of 8
12-10-2013 | Posts: 350
Joined: May 2004
Seems to me that an actual relay is best, an AC motor is usually controlled in the following fashion "line 1 connected, go up, line 2 connected, go down, if neither, stay still", so you can control the with 2 relays, that turns on or off line 1 and 2. Seeing that you could control almost any screen with this, it would suprise me if there is no relay that just drives the screen down (that is turn on relay 2) when the projector si on (when it receives 12V from the minijack) and runs the screen up again (relay 1), when the signal disappers. Or at the very least, a network connected relay or something I can't be the only one with this need? It would be great for all owners of an electrical screen without inbuilt 12V input?
SILVER TACO's Avatar SILVER TACO
12:23 AM Liked: 13
post #4 of 8
12-24-2013 | Posts: 6
Joined: Dec 2013

Its late but if I'm reading this right, you're looking for a relay for 12v dc input. If so this should work:

http://www.amazon.com/Metra-Install-E-123-Bay-Relay/dp/B000P61E36/ref=sr_1_2?ie=UTF8&qid=1387869669&sr=8-2&keywords=bosch+relay

It is a 12v dc relay used for automotive applications, but can be used in the household as well. Any auto part store should have them. They cost around $5 and are reliable as well.


SILVER TACO's Avatar SILVER TACO
12:26 AM Liked: 13
post #5 of 8
12-24-2013 | Posts: 6
Joined: Dec 2013

You should be able to use an automotive relay, assuming your input is 12v dc. They are rated for 30 amps. If you go to amazon, and search bosch relay, they will show up. They can also be found at auto parts stores as well for around $5.


ATWindsor's Avatar ATWindsor
05:35 AM Liked: 10
post #6 of 8
01-05-2014 | Posts: 350
Joined: May 2004
Quote:
Originally Posted by SILVER TACO View Post

Its late but if I'm reading this right, you're looking for a relay for 12v dc input. If so this should work:
http://www.amazon.com/Metra-Install-E-123-Bay-Relay/dp/B000P61E36/ref=sr_1_2?ie=UTF8&qid=1387869669&sr=8-2&keywords=bosch+relay
It is a 12v dc relay used for automotive applications, but can be used in the household as well. Any auto part store should have them. They cost around $5 and are reliable as well.

A relay has two downsides as i see it

1. The 12VDC is either on or off. So it will tell the motor to go down for the duration of the projector being on, and up for the duration of the projector being off. Seems a bit safer if something only sent signals to the motor for a limited amount of time. (that is only send the "run motor"-signal for maybe 30 seconds)

2. Is the 12VDC signal from the normal projector really enough to drive the magnet in a relay? They do use a bit of power.
SILVER TACO's Avatar SILVER TACO
09:03 PM Liked: 13
post #7 of 8
01-11-2014 | Posts: 6
Joined: Dec 2013
Regarding the first question, I'm not sure. I'm new to the home theatre game but I have an electrical background. I would have to have my hands on what you're talking about to give you an answer.

But for the 2nd question, these relays use very little power to operate, and I don't think you will have a problem with that.
AV Science Sales 5's Avatar AV Science Sales 5
10:11 AM Liked: 531
post #8 of 8
01-13-2014 | Posts: 8,373
Joined: Sep 2011
Quote:
Originally Posted by ATWindsor View Post

A 12V-signal via minijack from the projector to control a motorized screen is pretty normal. Almost all motors can be controlled by relays, so a relay which is controlled by a 12V-signal should be something that is highly useful. But I haven't found it, does anybody have a tip to where i can get something like this?

I use a lot of relays in my system. I have 120 volt mechanical relays for my power amps and I use an Opto-22 solid state relay mounted to a heat sink for a triggered relay for sequencing my amps off of the 12 volt trigger of my processor. The Opto-22 solid state relay is what you want, if you want to trigger your screen off of your 12 volt trigger, then this would work well for you.
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