So I was thinking that since I have a fixed screen and don't need to use the 12v trigger on my Optoma 72 that there may be something else cool I could do with it. Maybe a "Theater in Use" sign or something just for general coolness. Has anyone done this? Any creative thoughts about what do with an unused 12v trigger jack?

Seems like a terrible thing to waste. :)

JayW

12v triggers are useful for alot of things... practical or not. I have mine turn on my ropelight and my sub amps from my receivers 12v trigger. (using a 12v to 120v relay, cascaded and time delayed so they all turn on in order and with enough time between to not drop a breaker)

Did you purchase the relay circuit, and if so, where can I get one?

If built from scratch, can you share the schematic? I want to light up an LED to indicate that the projector has been switched on, but am not sure what to do to ensure I don't draw too many amps from my Sony's trigger jack.

Did you purchase the relay circuit, and if so, where can I get one?

If built from scratch, can you share the schematic? I want to light up an LED to indicate that the projector has been switched on, but am not sure what to do to ensure I don't draw too many amps from my Sony's trigger jack.


It's pretty straightforward;

Go to Radioshack and grab something like this (http://www.radioshack.com/product/index.jsp?productId=2062569&tab=features).

I don't know how far you want go from the projector; you will want to size the wire you use accordingly. All you need is a pair of wires and the right jack to fit the projector. If you aren't into soldering you could connect the LED to the wires with a crimp connector or a terminal block.

You should check your owner's manual to be sure of the max draw of the trigger, but it is meant to trigger a relay, so it should be good for ~200 mA (milliamp). The LED in the link above only draws 15 mA, so it won't be an issue.

Also keep in mind that most LED by themselves only require ~2-5 VDC, so they won't last long if you connect them to 12 VDC. The LED above from RS has a built-in resistor that allows you to use 12 VDC.

With the right relay you can control pretty much whatever you want; I use the trigger from my reciever to turn on 4 20A circuits, which powers my amps.

That looks like exactly what I need! Thank you!

Digikey or Mouser also carry low current 12v LEDs. That way you don't have to construct the resistor network to drop the 12v provided by the projector to 2-3v the LED needs. Just get a 1/8" mono headphone plug and wire it up to that... simple. And you can get the LED holder if you want to mount it to a panel somewhere.

And yes, with the right relays you can control just about anything. (add in some X10 stuff and you can do it remotely!) I made my circuit using some relays i had when i renovated a radio station. They used 12-24vdc control high current relays for the on-air lights in the studios. They got replaced by some low voltage stuff when they renovated, but the relays go for around $70 each at Digikey. (they're rated for 120vac@20A, high current)

1. change the set back on the thermostat.
2. lock the door to the room :)
3. turn on an exhaust fan (thermostatic control is better however)
4. turn on an "On the Air" light outside your room
5. start the morphine injection pump so you don't wake your wife ....

So if I run a cord from my Onkyo 805AVR to my power distribution center for my amps, I could use that to turn the amps on correct? Do you use a regular 1/8 pin connection for this setup? The amp is a DJ style amp for the subwoofers that I have on a different circuit.

Thanks,
JJ

So if I run a cord from my Onkyo 805AVR to my power distribution center for my amps, I could use that to turn the amps on correct? Do you use a regular 1/8 pin connection for this setup? The amp is a DJ style amp for the subwoofers that I have on a different circuit.

Thanks,
JJ

That will work fine. You just need to make sure the current required by whatever relay you use doesn't exceed the output of your Onkyo's trigger port.

I don't have my receiver hooked up yet, but here is a picture of the relay box:

I use a regular 1/8" mono jack out of the reciever to trigger the relays. Since I didn't want to run the risk of overloading the trigger output, I am using a separate 12v automotive style relay with a separate 12v 750mA power supply to switch the 4 other relays. Overkill, but I don't have to wory about it and I will be able to add more relays later without doing anything else.

Each of the 4 large relays in the picture is a 30 amp 270 VAC relay with a 12 VDC coil. they each switch one 20A circuit.

I have them setup like this:

Relay 1 Sub amp (Nady SPA1400)
Relay 2-3 Behringer A500 amps (Mains)
Relay 3-3 Behringer A500 amps (Center and surrounds)
Relay 4-X-overs, Feedback destroyer, etc.

Picture didn't show up in the last post...



http://i83.photobucket.com/albums/j288/beemer533/IMG_0402.jpg

I was expecting to see a wall-wart providing the secondary 12v power at 750ma, but don't see a transformer in the box.

Did you build your own powersupply and is the circuit board at the right part of it?

Is the black expoxy box in the lower left the automotive relay?

I was expecting to see a wall-wart providing the secondary 12v power at 750ma, but don't see a transformer in the box.

Did you build your own powersupply and is the circuit board at the right part of it?

Is the black expoxy box in the lower left the automotive relay?

The lower left is the automotive relay. Looks to be a typical single pole, double throw.

The lower left is the automotive relay. Looks to be a typical single pole, double throw.

You're right, the lower left relay is the automotive relay. It's a SPST. I don't have the power supply in the picture; it is a wal-wart from Radioshack. It and the trigger plug into the top of the box with 2 1/8" jacks. You can't really see them in the picture.

The PCB in the box is my timer circuit which, when triggered by the reciever, starts a 10 second delay before turning on the amps. This is to prevent speaker thumps.

You're right, the lower left relay is the automotive relay. It's a SPST.
My bad, I thought I saw an extra pin (87a) in there.

Well, it is kind of odd, if you look at up close it looks like they just shaved that pin off flush. I'm not sure if the functionality is there, but since I only needed the SPST functionality I didn't really check.

Probably some sort of cost saving production method....

It was cheaper, at least!

great posts, thanks for the tips. im looking to do similar with some "cool factor". just out of curiosity, instead of using the 12v trigger from say a receiver, etc. to power on amps and other stuff in my rack, if have all my front end components plugged into a switched 120v outlet, and leave them always in the on position, would it hurt them in any way if i use a switch to turn the circuit on and off? this would basically be like pulling out the power cable from each component when they are essentially on. not sure if it will reduce any of the internals sooner. any advice would be great. thanks.

Won't be an issue; it is essentially the same thing I am doing, except instead of using a switch, I am using a relay to do it for me.

End result for both is the power gets disconnected from the amp.