Running fans off a 12v trigger?

I take it that the triggers are always powered up when the receiver is powered up? That makes sense, but I never tested it.

Seems using one per fan is safer as the total draw is 100ma, and they are not really designed for driving loads.

I doubt the current in the 12v trigger will be enough to power the fans.

Fans are a nasty inductive motor load. That means big turn-on and turn-off spikes that your AVR's trigger outputs might not like even if the steady-state draw is low enough that your trigger circuit would power them. While you can design a little circuitry to protect the AVR, I personally would not hang a fan on the trigger circuit. It's just not the thing the trigger circuits are designed to drive. You couild get one of the power strips that take a trigger input instead if that's an option, then powre the fans off a cheap 12 V (or whatever) supply plugged into that. For that matter, I used an X10 transmitter that has a voltage input driven off my trigger circuit, then a pair of X10 receiver modules to switch on my subwoofers when the AVR comes on.

http://www.thehomeautomationstore.com/psc01.html
http://www.thehomeautomationstore.com/pam02.html

Because it is what it says it is. A trigger only, not a form of a continuous power supply. There are many options to do what you want and do it safely without the chance of damaging your current equipment. Go over to coolerguys.com and click on their section for HT cooling options. They have any configuration you want as far as fans and other cooling options go. Way less expensive than what may happen to your gear if you try what you want to do. Good luck and hope you find your answer.

No questions are here are stupid. Just need to be led down the right path. Not anyone here knows everything. Coolerguys does have the 1 or 2 fan solution for you. 120mm computer case fans draw the most heat from your equipment and are the quietest in doing it. Again good luck.

This is just an idea for you to look into where your are located. Also all you need to get in order to do it.



http://www.coolerguys.com/comcool.html

Over some years I've found different types of 12v triggers in assorted equipment I've owned.
More recent gear, if it's well thought out, should probably give you some kind of programming options, other then just setting them to on/off.

For example:

You may be givin the option to select a steady DC signal or pulse type.

If pulse is an option, a setting for the duration of the pulse is handy.

If more then one trigger is supplied or in use, you might be able to select whether or not they will all turn on/off at the same time or allow to be set sequentially.

If a sequential option is provided, a setting for how many seconds in-between before the next trigger is activated might also be available.

My old SSP had 4 - 12v triggers that were not programmable and set at the factory to be a continuous 12v signal, they were mostly useless to me as that type of signal would turn my 3 power amps right off, instead of taking them in or out of stand-by.

My power center (Monster type device) on the other hand requires a steady 12v signal to stay on.

Almost any power supply would work that is 12V and rated for the combined current draw of the fans (assuming you connect the fans in parallel and leave yourself some margin on the current rating). Virtually any power supply can handle the turn on spike current from such fans, worst case the voltage drops a bit which will still spin up the fan just more slowly but still within a couple seconds. This isn't infinitely expandable, i mean you may run into trouble with 10 fans but 4 should be fine.

Get fans that have a 'PWM input' rated for 12V. Feeding this with a constant 12V from the receiver output will cause them to run at full speed and draw very little current from the receiver.

This is exactly what the 'coolerguys' package mentioned above does.

a few thoughts:

1. Does your receiver have a switched power outlet? If so, you should be able to run a small power supply on it to power some fans. I have certainly read about people doing just this.

2. What receiver (make/model)? Maybe someone can lookup the specs of the trigger circuit, or has tried running fans off the trigger circuit of the same receiver.

3. How many fans do you really need? The true answer might be zero, in which case you can save yourself the hassle of buying anything and adding noise and system complexity. Consider measuring temps, with your own measurement equipment, or using a button code to show the internal temp sensor readings from the receiver's sensor(s). That way you can use real data to judge if you need fan and/or optimize the size / type / speed / placement of any that you do decide to purchase and install. It is easy to talk yourself into an apparent overkill solution, and then later realize that you can hear the fans after all, or that you just don't want the mess and complexity of extra fans after you've had the system for a while. Personally, I don't want any fans -- I prefer passive solutions such as a more open cabinet, or just accepting that some gear runs warm/hot -- it will probably be obsolete before it cooks itself anyway (if it ever really does cook itself).

-Max

There are dedicated 12 VDC power supplies, which are being used for powering HDs (computer hard discs). Even some 120 mm fans come already equipped with the corresponding Molex connectors. That's what i used.

I have the trigger option on my pioneer THX receiver. Does coolerguys have a fan or controller I can use as a relay? I have plenty of power 12v supplys laying around.

http://www.coolerguys.com/

The trigger output is capable of supplying 150mA at 12V...that's all the information required. You could run 3, 12v 50mA fans.

except for pioneer

would something like this work with a small 80mm fan with a 12v 500ma power supply? does it get wired like a regular automotive type relay?


http://www.radioshack.com/product/in...ductId=2062479

I don't think the OPis using a Pioneer, he gave the specs in th first post:





Maximum switching current is 500mA, coil voltage appears to be 5V.