Hello,

I will most likely have to place a Yamaha RX-Z1 receiver in a pretty tight cabinet, along with a couple of components.

My question is...I would like to mount a couple of 4" cooling fans to exhaust the hot air out in the back of the cabinet. Can I hook them up to the remote 12v trigger from the back of the receiver and not worry about them eventually popping anything within the receiver? The fans are 12v and each are rated at .49 amp. I just was not able to find any specs on the output voltage/amps of the 12v trigger from Yam's site and want to make sure this would be a safe way of doing it? Any possibility of fan motor noise returning through the 12v trigger circuit to pollute anything within the receiver?

My other option is to use 120v fans, but still would need to plug them into the back of the receiver so they can be activated automatically when the unit is powered on.

Thanks for your help and suggestions

CK

Trigger output often have 15ma of output, and some of the later ones 100ma. We connect a low voltage relay to the trigger output to protect it, and then trigger a 12v or 120 fan from that.

Exactly.

Since you do not actually know how much current draw will make your receiver into a boat anchor, even temporarily, do not even think of putting a real load on it.

The best and worst of this that I have seen is a Marantz projector that has 12volts out, but if you try to draw more than a couple of milliamps, it drops quite a lot. It acted like 12 volts with 50k ohms in series with it.

Even safer than having the trigger drive a relay -- the Marantz would not even do that -- is to make up a little control circuit using a 2N3904 transistor as a DC switch to trigger a relay. You get a power supply that will drive the relay, then connect the transistor as a common collector amp with the trigger voltage being the input through a 1K resistor. I can fax you a sketch if you like.

That GUARANTEES to isolate your real world loads from what might be a low-current source, or even worse, might have been designed by a well-meaning engineer who did not realize that the current output specs would not simply be published as part of the manual, and who did not bother to make it bulletproof....

Making your own interfaces is always an option if your handy with that kind of stuff, but Niles already has one put together in a nice little box called the OTI-512.THis wil take any 5-12v Low current output and turn it into a high current 12v output.

Had to use on on a B&K ref 50 a couple weeks ago... was trying to trip a standard relay with the output and didnt have enough current to even do that....

I am open to all and any suggestions. Of course the simplest way with the least amount of components is best. But one that works and has been used before is worth a look at.

Yes I would like a sketch of what you have mentioned and maybe some part numbers as well. Maybe I can pick up the things at Radio Shack easily enough. You can fax to me at 954-659-6085 ATTEN: Corey

>Making your own interfaces is always an option if your handy with that kind of stuff, but Niles already has one put together in a nice little box called the OTI-512.THis wil take any 5-12v Low current output >and turn it into a high current 12v output.

I hear your option as well....Is there a link to a page I can see and possibly order one of these if I decide to go this route?

One thing I found interesting, in reading some reviews regarding this receiver, one tester in particular had problems with the remote 12v trigger not being able to turn on a device or two. Does this mean the 12v trigger is a VERY low output and weak source to begin with? That's one thing that concerns me about driving even a couple of .50 amp mini cooling fans off of it directly. Still it would be so easy and convienent to attach the fans here and have them activated this way.

Any views on if this will introduce noise back in through the electric circuit to the reciever from the fan motor's? Or really not likely?

Thanks

CK

I normally use a 110v to 12v transfo plugged into the switched outlet of the receiver to drive a 12volts fan

The 12V Triggers on almost all Pre-amps and receivers are stricly designed to send Trip Voltage. None of them are designed (That i know of) to run a Fan. This is why you need some sort of relay to make the Low Current Run the high Current device.

the OTI-512 can be found HERE

I dont know of any online Distributors, You might need to find a local dealer

I looked at this Niles box. It would look to be one of the safer bets. I also like and may just use Stephane's idea of running of one the receiver's 110v switched outlets with a transformer to 12v and wire up the fans. Unless I use the proper gear as you mention, I won't mess around with the triggers.

Good info and solutions from all....Many Thanks

CK

Yeah, the Switched outlet thing works good as well.. Only drawback is that you cant control the Fan on/off independant of what the receiver is doing.... Meaning, the fan is going to be on whenever the Receiver is on... At least the 12v Trigger can be turned on and off independantly.....

Interesting problem pops up: the Niles unit requires 20 ma., but my pre/pro (B&K AVP-4090) is capable of only the same 15 ma. that Theaterworks mentioned.

To overcome this limitation, I used a relay with the lowest coil current I could find (11 ma.), which is a reed relay. Even then, it wasn't capable of the coil current of the contactor I wanted to use.

So, I did what any respectable engineer would do: use more parts; I cascaded relays. The reed relay controls a 5-amp relay, which in turn controls a 4-pole, 25-amp contactor, one for each of my switched circuits.

Just to mention them, they are 1) all the switched components and wall warts, 2) the stereo amp running my mains, 3) the 5-channel amp running the center/sides/rears, and 4) the two powered sub amps.

I used a small 'experimentor's PC board' to mount and wire the reed and 5-amp relays and placed the entire package inside a tough plactic pouch, and fit that and the contactor inside the 4-space/8-circuit sub-panel in my closet.

I mounted an RCA jack on the front of the sub-panel, mainly because the B&K trigger uses one, and wouldn't require a custom cable. A short RCA cable connects the pre/pro to the sub-panel.

Larry
www.fineelectricco.com

There is a really effective but hokey way to solve this, too -- Home Depot, out here, has a mercury-switch thermostat for about ten dollars that has a cooling switch as well as a heating switch.

I put one of these in a box that was really too small for the Mits XD300 running in it. I had to rotate it off level to get it to turn on at about 120 degrees, so proximity to the un-AC'd attic air would not start it on a hot day, but it would still work to cool the projector. It runs for about ten minutes after the projector turns off.

Meanwhile, the 12 volts comes from a wall wart, and nobody triggers nuthin nohow.

Darn,

Reading through this forum I thought Id be able to provide some insight but Ernie beat me to it. We use cooling stats that we buy from a local HVAC company and tie them in to the fan... set them at 85 degrees and were done.

This may seem like overkill but we often use a Nutone LS-80 model bathroom fan and duct it outside (lots of custom labor this way. The best part of this fan is that it runs at 0.8 sones (very quiet). Most of the AC 4" fans are screamers.

You also need to make provisions for air intake. We usually drill holes below in the toe kick to bring room air into the cabinet or change doors to screened material. It is very important to keep your equipmnet cool... we always make cooling a part of any proposal we do.

Thanks. I'm now feeling really pleased with myself this morning. Thinking of the thermostat was a kind of DUH moment....


Yeah, I wanted to do that, but I could not find a way to keep breezes from gently wafting their way back in. Since one of these is 3 feet directly above a bed, a tiny breeze would be really obvious. And I'm in Southern California; I REALLY don't recommend venting to the outside in Minnesota!