Using 12v trigger to run accessory fans

[cmr15]

I've got a 1067 which runs rather hot, and I'm aware that that's the norm. I'm about to place it in a custom wall unit and need a little info regarding the use of fans and a 12v trigger.

What I'd like to do is use 2 accessory computer fans to circulate the air. One would pull in air from the basement below, and the other would pull air out of the cabinet through a ventilation slot above the AVR.

The only problem is that I don't know what to buy and how to set it up. I read an earlier post which suggested hooking a fan/fans into a power supply which was then put into the "switched" outlet on the back of the 1067. The problem is that it doesn't have one.

Can I use the 12v trigger to somehow turn off/on a power strip that is then hooked up to the fans?

I spoke to a guy at Radio Shack who said I could (and he has set it up for other customers) if the Rotel 12v trigger is the kind that just pulsed on/off rather than actually supplying power.

Do any of you know if the 12v trigger is that kind or does it supply 12v power. Any suggestions would be very helpful.

Thanks,
Craig

[soundhound]

I believe it's 12 vdc, 200 ma.

[Andrew Pratt]

Sears sells a power strip like device that's more like a square then a strip but what its intended for is to power on exhaust fans or vacuums when other dust generating devices are turned on like table saws. They're located in the tools area and are pretty cheap. You could use on of those to toggle fans on that are plugged into the unit if you had them running from a wall adapter to downstep the current to 12 volts etc. I wouldn't try powering fans directly from the 12Volt triggers...not that you were suggesting that just warning others not to try it.

[DelRay]

One of my 12 volt triggers from the 1068 turns on the amps via the delay outlets and the other turns on the switched outlet of my Monster 3500. My fan plugs into the switched outlet. Has about a 10 second delay. My fan is 12 volts dc and has a variable (1.5,3,4.5 etc) switch on the transformer. I set it to 4.5 volts. the fan is really quiet.

[PiDD]

You can do exactly what you want. Its pretty easy but you have to do some reading.

I have a couple fans on my 1095 that are controlled by the amp trigger on the 1098.

First get a PC power supply... an ATX one is easy to jumper to stay on.

Wire a relay that gets triggered from your pre and powers the fans.

Check this out for a bit of a description.

[DOUGAL]

You can do exactly what you want. Its pretty easy but you have to do some reading.

I have a couple fans on my 1095 that are controlled by the amp trigger on the 1098.

First get a PC power supply... an ATX one is easy to jumper to stay on.

Wire a relay that gets triggered from your pre and powers the fans.

Check this out for a bit of a description.

Love the above ground swimming pool :W
Very very nice HT set up.
how do you keep your AMPS cool in the rack.

cheers

[cmr15]

Thanks for the info.

I must admit I'm hardly an electrician, but the above suggestions should do the trick.

Craig

[miagi]

Hmmm....why not use the 12v dc ?? - If it can provide 200mA, then there is alot of fan´s on the market??

[Bostonears]

If you've got a Motorola cable TV set top box, check out this post http://www.dvrchatter.com/viewtopic.php?pid=1070#p1070 about a clever way to power a fan by plugging it into the unused USB port on the set top box.

[cmr15]

Hmmm....why not use the 12v dc ?? - If it can provide 200mA, then there is alot of fan´s on the market??

How would I do that, do I just plug the two leads from the computer fan into the trigger output on the receiver?

Craig

[w6000]

Russound Makes a 12v trigger switched outlet. You would plug the fan into the outlet then run the the 12 volt trigger to the 1067. Fan would go on and off with the 1067.

[Kevin D]

Hmmm....why not use the 12v dc ?? - If it can provide 200mA, then there is alot of fan´s on the market??

Careful with that! I don't know of many affordable 12v fans out there that could provide enough flow to do any good and draw less than 200mA.. Especially when you usually need two for a push/pull system..

Kevin D.

[soundhound]

Go to Radio Shack, find a low current (400 ohm or higher coil) 12vdc dpdt relay with descent contacts, 120vac @ 3-5 amps, and fire the relay with the trigger and let contacts switch the ac fans. I don't know what Russound gets for theirs but one could make one cheaply enough, and get some pretty descent cfm.

[PewterTA]

Need a little help...

Would this type of relay that soundhound mentioned, can it be used to do this...

What I want to do is have my 250watt Antec computer power supply turn on with the 12v from my 1098. I know I can bridge the connection of the power supply (green power on wire and black ground wire) and as soon as power hits it, it starts up. Now what I want to do is have the trigger from my 1095 amp go and cause the power supply to turn on. I don't want to leave the power supply on all the time, just have it turn on when the home theater is on. I'm going to use it to power some extra 80mm fans I have to help cool down the 1095 and 1098 since they are in some tight quarters.

Then later on I'd like to take the 250watt power supply and use it's 12v power lines to run LED strips to light up the glass shelving (which I don't have yet). I believe the 250watt PS should be enough to drive 3 - 6 80mm fans and also a couple LED strips...

Does this sound like a do-able thing? What do I need to get/buy to allow the 12vdc from the pass through on the 1095 trigger the Antec Power Supply to come on (and shut off when the amp shuts off)???

Thanks for your help!!!

-Dan

[soundhound]

Pewter,the power supply is 110vac @ x amount of wattage. Make sure the 12vdc relay you buy (turned on and off w/ 12 volt trigger) has contacts capable of switching the 110 vac for the pc supply. Power measured in watts = current x voltage. If you know 2 of these values you can figure out the third. Divide the power consumption on the power supply by line voltage (120) and this will give you it's current draw. Again, just make sure to get a 12 vdc control relay (high enough impedance to stay under 200ma draw)that has contacts rated to handle the voltage and current the power supply will draw as well . If you need a hand with specifics just email me.

[Clemo]

I had a similar problem with heat. I used a Furman PST-10D power conditioner which has 10 outlets of which 3 outlets are 12 V triggered off my processor. I plugged the amp (Rotel RMB985 mkII which has no trigger) into one outlet and a Radio Shack 3-12 volt Universal Power Adapter, (the one with switchable volatages), into another outlet. The Rat Shack adapter drives four 12 volt computer fans in my equipment rack in a push-pull configuration. The adapter is set to 3 volts which makes the fans run really quiet and gives me all the cooling I need.

[PewterTA]

Thanks for the info Clemo, that's what I'm going to do (basically).

Since I have a 250watt (basically brand new) Antec power supply (I replaced it after getting my case a couple years ago with a 330 or 430, can't remember which), that is just sitting in my closet, I figured I might as well put it to some good use. I have 4 80mm Blue LED computer fans that are also sitting around so why not use them. Then plus when I get my glass shelves I'll be adding blue LED strips to the back to light the glass up. All of which can be easily powered by this one single power supply.

So what I'm going to do (for the moment) is place some molding tape around the one side of each fan and just place them on top of the components until I figure out exactly where I want everything. This way it will cool and I will have an idea what kind of noise they are going to produce. Plus each fan has both a thermal control to it and a manual control so I can speed them from 1400 RPMs to 4800 RPMs. So hopefully they will run really quiet with the thermal control and I can limit how fast they can go.

Plus I can judge just how bright these fans will be when it's dark (see if they will be annoying or not).

[Stevebez]

Just to throw a spanner into the works here this is what I have done... but reading this thread it seems your system is a simpler and perhaps a more effective method.

Anyhow it goes like this ... I have hooked up a thermostat inside my cabinet which triggers a 12v relay to a power supply which in turn powers 5 ultra quiet fans ... 4 pushing from below and 1 pulling from above once heat inside the cabinet builds up to over approx 27deg C - which means often the fan system is on ... and then there is the little annoying issue of it switching on/off sometimes and the benefit of quiet operation while cold is of not much benefit... so if you were considering the possibility of a thermostat type system - I don't think its worth the effort.

But ...!! there are also some more sophisticated devices that vary fan speed with temperature - this is perhaps the ideal setup - but for some reason cannot get this device to work properly!!! If someone has please let me know...

More feedback once I have some time to tinker at home alone !!!

Rgds Steve.

[soundhound]

Steve, what type of device are you trying to use to get thermally varied (voltage)speed from. There are a few ways to do this. One would be to run a feedback loop to monitor rpm vs temp and an algorithym to set the rpm. This would take a processor/firmware. Most devices with 2 leads will be a thermal switch, not capable of an analog (variable) output.

[Woo Wooooo]

Just get one of these....... :T

http://www.middleatlantic.com/rackac...ng/cooling.htm :B

[Kevin D]

But ...!! there are also some more sophisticated devices that vary fan speed with temperature - this is perhaps the ideal setup - but for some reason cannot get this device to work properly!!! If someone has please let me know...
Rgds Steve.

You can do what I did, but it does take a lot of work. I'm an AMX programmer by trade, so I pick up a lot of the older stuff to use at my house. With my 1098 controlled by 2-way RS232, the system always knows what volume level I'm at.

I dropped a voltage ramp card into the system connected to some fans venting into the laundry room. At MIN-40 volume, the fans run at 4volts. 80-MAX runs at 13.8volts. 40-80 is a smooth ramp from 4-13.8volts up and down. That's for music sources for where the music will be loud enough to drown out loud fans at the higher levels.

For movie sources, the voltage multiplier gets lowered so that the fans max out at about 10volts. This keeps the fans from being heard during quite passages.

For those wanting more fans at a slower speed, look into getting a PWM power supply circuit (I built one from a kit). This always sends max voltage to the fans, but will turn the power on and off very quickly(100+ times a second). By varing the ON-VS-OFF times (determined by a reference voltage) you can simulate sending 2volts to the fans but actually be sending 12volts. Sending lower than 6 actual volts tends to have problems starting the fans from a stop and also can create 'growling' sounds from them not operating at normal power levels.

Kevin D.

[Stevebez]

Yep thats what happens to my fans when I tried to use a Pyramid V thermostatic variable fan control... fans dont start and they ... well... "growl" ... anyway to overcome this Kev with this device ? Maybe place the device at the hottest spot?

Rgds Steve.

[PewterTA]

Well I got mine all set up for what it is now since the rack isn't built yet and I don't have the glass shelves nor LED strips to light them... The pictures are up in the rotel gear thread with all the info...

Basically just used a 250watt computer power supply, hooked up 3 (for the moment) 80mm fans with blue LEDs that I had laying around and for a matter of $12 built my own 12volt trigger, so it powers them on. They are thermally controlled by sensors I dropped down into both my 1095 and 1098 to monitor the temp. The fans run at 1400 RPM moving about 22CFM at 17dBA, so they are virtually silent. Everything shut off in the room and my ear to the front of the cabinet and I can't hear them running. Plus they look cool as they are sitting directly on top of the units (until I figure out what my rack system will look like).

Many many thanks go out to Soundhound for pointing me in the right direction for what relay I needed, thanks bro!

[Kevin D]

Yep thats what happens to my fans when I tried to use a Pyramid V thermostatic variable fan control... fans dont start and they ... well... "growl" ... anyway to overcome this Kev with this device ? Maybe place the device at the hottest spot?

Rgds Steve.

I would imagine that the variable fan control outputs variable voltage. You could certianly use the kit I did or any other pre-built kit. It basically has 12v & ground in, 12v & ground out, REFERENCEv & ground in. You would place a clean power supply into the 12v input, hook the fans to the 12v output, and then hook the voltage wire coming from the Pyramid device into the REFERENCEv input. As the voltage drops on the reference line, it changes the pulse widths on the output to simulate the lower voltage (but always sending a full 12volts).

This is all simplified, and some electronic & circuit experience will be required. Google 'PWM fan controllers' and start reading..

Kevn D.

[PewterTA]

All you need to (manually control the fans) that is cheap is a rheostat hooked inline.