Temp/Timing Circuit

[dtyrrell]

I have several 12 vdc exhaust fans in my Mobile Homes ceiling. Instead of turning each of these on/off individually I was looking for a possible circuit that could turn these fans on/off for a predetermined time (ie. 15-30 mins) but only when inside temperature reached around 80°F and then reset itself for a new cycle, until temp has dropped below the set temp of 80°F. Can anyone help me?

 

[ericgibbs]

hi and welcome,

Do you know the wattage or current rating of the 12volt fans

E

 

[MikeMl]

Do you have 120V/240V AC available?

 

[dtyrrell]

yes...120vac is available, but would prefer to use all 12vdc

 

[dtyrrell]

they have an approx. 4 amp draw

 

[MikeMl]

yes...120vac is available, but would prefer to use all 12vdc

Reason I asked is I have used used home heating/cooling thermostats I bought at Habitat For Humanity thrift store for $1 for a similar project. However, they operate on 24VAC; work fine on AC Wall-Wart.

 

[dtyrrell]

I have thought of using a thermostat as the temp sensing section of what I need, but as you said, they operate off of 24vac....and even 120vac is scarce as all my 120vac comes from an inverter off of solar panels

 

[ClydeCrashKop]

Maybe you could find an old thermostat with a mercury switch. It could operate a MOSFET.