I thought i'd post how i made my projector control my screen using the 12V trigger output and a £10 circuit from Quasar electronics - www.quasarelectronics.com/3084.htm My screen had a rocker switch that you pressed for up and down. The screen automatically stops at the top and bottom. I took the four wires from the screen (up, down, earth and neutral) and wired them into the circuit board. I also needed to wire in a 12V adapter plug (which i had from an old mobile phone) to power the circuit and connected up an wire to the projector. The main problem i had was that the supplied drawings of the cicuit board did not match the actual PCB! Therefore i've attached a picture of the circuit board with my wiring. It goes without saying you should be very careful doing this and i didnt test with the projector until i had it all working (instead of the projector i used another 12v adapter and plugged/unplugged it to mimic the projector coming on) I did it by a lot of trial and error (as i have forgotten my electronics degree!) so i might not be able to answer every question. Hope this helps others.