Need help with relay for controlling electric projector screen, schematic included

[Picarro]

Hello fellow Electro-Tech members,


I have bought an electric projector screen. I cheaped out, and got the version without a 12v controlled drive. Now I've gotten tired of having to manually press the remote, and I want to make it controlled by the 12v port on my projector.


The screen came with a remote control, and I have opened this and want to use it. In theory it's simple enough. If I short the two pins connected by the switches the screen goes up or down, depending on which pins I short.
My projector puts out a 12v impulse when it is turned on, and an impulse when it is turned off. I want to create a system that "splits" the 12v impulses. The first impulse needs to go to a relay that shorts the "down" switch, and the second impulse needs to go to a relay that shortens the "up" switch.


My problem is, that I do not know which types of relays that I need. I think I need a bistable relay for "RLY1" in the drawing, and normal relays (2&3) that are "on" when power is applied, and "off" when the power goes off. This way I don't continously short out the pins draining the remote of power.


Looking at the schematic, the voltage that powers the first relay to change, also powers the second relays to change. This way, no secondary PSU is required for the voltage needed for them to shift.
The 1 and 2 on the "Remote PSU" simply denotes + and - poles.


Here is the schematic,

TLDR; what kind of relays do I need for 1 and 2-3?

 

[crutschow]

RLY1 could be an impluse type alternate action relay.

RLY2 and RELY3 can be any 12Vdc low current relay.

Does you projector output enough current to operate a relay? It may be only designed to trigger an electronic circuit that has a high impedance input. In that case you will need an additional power supply and a transistor buffer amp to drive the relays.