greenhouse automatic blind closer project

[hairyhippy]

I would like to build a little control circuit that closes some blinds on the inside of the greenhouse roof when it gets too hot, ten opens them again when it cools down again. I'm thinking about motor, a couple of microswitches to stop the blind at either end and some sort of temperature sensor. I've googled but can't find anything like this. Does anyone have any ideas?

TIA.

[mike]

I've got one that opens the big flap in the roof of the greenhouse when it gets hot. I think it cost about 10 - 20 quid  from the garden centre.

[hairyhippy]

I've got 4 autovents for the windows, but I'd like to roll some shade over as well.

[mike]

aah..   Could you use a ram from an auto vent to pull a chain round a sprocket, opening  / closing the blinds?

[rogerzilla]

They must exist, because our office has hundreds of them in the atrium areas. 

They disabled the ones in the roof after people complained.  Flies were trying to escape through the glass roof, becoming trapped and dying, their dessicated bodies being caught on the blinds.  The next time the sun went in and the blinds automatically rolled back, people found dead flies landing in their coffee