CurtPalme.com Home Theater Forum

ecrabb

OK, I need some help from you electronics boys... I'm getting close to getting my HT fully automated from my iPhone using Itai's (from AVS) iRule iPhone app... I'll start a new thread on that for anybody who's interested, but it talks to serial and IR devices over IP via a Global Caché GC-100 Network Adapter and to IP devices (like my prepro) directly.

One missing piece I'd like to resolve ASAP is turning the hush box on and off with the projector. The GC-100 has 3 dry contact relays... The quick start guide describes them like this:

Now, I've wired up a simple low-voltage circuit from an AMX controller for a 110V powered screen before... It was easy because the AMX controller has outputs that go high and low, and they're designed to drive a relay primary coil. Cake. The GC-100 is just a dry contact, so I don't know how to wire it...

The thing I'm concerned about... If I put, say a 12v wall wart in series with the GC-100's dry contact and the DC relay I bought, when the GC-100 closes the contact, it's basically a short-circuit, through the coil in my outboard relay right?

So, can somebody tell me how I can wire the wall wart with my relay so the dry contact won't just short through the relay coil.

Thanks!!!

If anybody's interested, I'd also be happy to start a new thread about iRule... I'm a beta tester and I'm really enjoying designing my own buttons and UI.

SC

**Curt Palme** · Posted: Sun Nov 29, 2009 12:05 am Post subject:

Huh? I don't quite get the question.

Sounds like you're doing it right.

Consider your GC 100 relay simply as an on/off switch. Wire the external relay coil, the AC adapter and the GC 100 contacts all in series with each other. That's all there is to it.

ecrabb · Posted: Sun Nov 29, 2009 1:48 am Post subject:

Oh, so it's not a short circuit? Is the resistance high enough through the coil on the relay that it's just a standard load?

I just wanted to make sure I wasn't going to fry the relay or short the power supply.

Thanks, Curt!!!

SC

**Curt Palme** · Posted: Sun Nov 29, 2009 1:50 am Post subject:

Just before you go blowing stuff up... Wink

Assuming you've connected the power supply right to your screen trigger relay and it works, then put the GC100 in series with the supply and external relay and you're good to go.

As long as the power supply is rated at the same voltage as your external relay coil, you'll be fine.

ecrabb · Posted: Sun Nov 29, 2009 2:02 am Post subject:

Yeah, I'll definitely test it before the throw the GC-100 in the loop.

The primary coil in the relay I bought is 12vdc @ 75mA. I was just going to scrounge up a wall wart around the house - 12v @ 200 or 300mA output. Maybe something from a cordless phone or something. The relay in the GC-100 is rated 24vdc@500mA, so I'm way good there. The switched circuit in my relay is 110vac@10A, and I'm just switching a Fantech fan that's probably only a couple of amps. So, I think I'm good to go.

SC

zaphod · Joined: 16 Jun 2006 Posts: 2002 Location: Cloverdale

when i put in the hushbox ventilation i used a thermorelay 110 switch that turned the fan on when the temp hit 40'

ecrabb · Posted: Sun Nov 29, 2009 2:23 am Post subject:

I had actually planned on a thermostat-based solution... But, since I have the automation anyway, I thought I'd just use it. It's simple... It'll come on with the projector, and go off with the projector.

I think I'll put a temp alarm on the box though - just in case the fan would ever fail for any reason.

SC

**Curt Palme** · Posted: Sun Nov 29, 2009 2:26 am Post subject:

Let me guess. The alarm will ring your Iphone. You'll then use your Iphone to correct things.

Your monthly data bill will be astronomical! Very Happy

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

Are you sure that primary is only 75ma? That's not much current .

ecrabb · Posted: Sun Nov 29, 2009 3:09 am Post subject:

zaphod · Joined: 16 Jun 2006 Posts: 2002 Location: Cloverdale

ecrabb · Posted: Mon Nov 30, 2009 2:12 am Post subject:

Hmm... I thought about the temp after shut-down, too... But, will the temp really spike that much if you're keeping it plenty cool when it's running? I mean, the fan and water pump in your car don't keep running after you shut off the ignition! Wink

Seriously, though... Assuming my machine is running cooler than when it's hanging in free air already, how much temp bump does the box see? 10 or 15 degrees, and for maybe 10 or 15 minutes before it dissipates?

I didn't think about it, but I could do it with my automation system... Just wait 15 minutes or whatever.

SC

zaphod · Joined: 16 Jun 2006 Posts: 2002 Location: Cloverdale

i don't know how much of a bump there is. good question. as for your car ... well if you have a model with guages, then after you turn off the engine, if you leave the key in the accessory position you will see the temperature guage rise before it starts to drop.

greg_mitch · Joined: 03 May 2006 Posts: 5321

The radiator fan will run on the car until the temperature is satisfied or the delay has been ran through.

I only know enough about relays and contacts to be dangerous but dry contacts are not meant to switch a power source. Is that what you are using it for?

You would normally get the contact from the controller to the auxiliary contact on the relay. When that contact closes (or opens) then it will actually switch the 120V to the fan. Maybe that is what you were talking about before anyway?

ecrabb · Posted: Mon Nov 30, 2009 7:43 am Post subject:

Yeah, I know the coolant temp climbs... There's a lot of mass immediately surrounding the cylinders that hasn't given up its heat yet when you cut the key...

zaphod · Joined: 16 Jun 2006 Posts: 2002 Location: Cloverdale

hey Greg,

yeah, i wasn't suggesting driving 120 through the relay Smile

i grabbed myself a 120 rated disk switch that closes at a specific temp. for the live of me i can't remember what they are called.. sigh. old timers disease.

mp20748 · Posted: Mon Nov 30, 2009 4:58 pm Post subject:

Person99 · Joined: 09 Mar 2006 Posts: 4901 Location: Flower Mound, TX