Timer for fans?

[Brian Kidd]

This really isn't for a CNC machine but it could be applicable if desired. Basically I am looking either a comercially avaliable or DIY timer that will turn a couple 110v fans off after a set period of time, say 30 minutes or so. What I am doing is mounting my Plasma TV above a gas fireplace. I am building a mantle that will be between the fireplace and Plasma and incorporating a box that has two fans that will blow air beneath the mantle to keep the hot air from rising up to the Plasma. The mantle will shield the Plasma somewhat but I want the extra safety with the fans. What I want to do is since the fireplace radiates heat for some time after it is shut off I would like to have the fans stay on for 1/2 hour or so longer then shut down. Basically I am either going to tie into the switch that turns the fireplace on with the power to the fans or I am going to have a seperate switch that turns on and off the fans. Many times we shut the fireplace down just as we turn in for bed so I don't want to have to wait around to turn them off later. I am thinking in might be possible with relays and a regular timer but not 100% sure of the logistics.

Thanks
B.Kidd

[mlaws1172]

just put a thermostat on the fans, alot of times things will heat up again after the fans shut off. the thermostat will turn things on or off as needed. You can use a line voltage stat.
mike

[DareBee]

Thermostat would be the cheapest, I built the same circuit for my VMC to shut down the air, chiller and spindle fan after the machine has been e-stopped for 1/2 hour.
It took some relays, a couple of Omron timer blocks and wiring, in your case you would need a panel as well, works great but pricey for your application.

[Brian Kidd]

Thanks guys, that's a hell of an idea and like mentioned would probably be the easiest and cheapest, plus probably the most practical. Sometimes you get an idea in your mind about how you want to do something and you spend all your time concentrating on the logistics of it and completely miss an easier better method.

Thanks again
B.Kidd

[ViperTX]

Brian.....look at snap action thermostats.....they are pretty simple.....darn I should be charging for all these solutions....