A new project

[Oliver]

Hi,

Sounds like a fun project.  I'm not sure exactly how you will do it, but can't you do this just with logic gates, and leave out the relays?  I think it should be simpler, smaller, and use less power.

[Oliver]

I haven't used parallel ports for much before, but I think they're not overly complicated.

I think your current plan is to switch some control signals for the remote via relays, right?  So probably this could be done using transistors instead.  I've only used relays when I've needed to switch fairly large currents, or AC currents.  You shouldn't normally need to use relays for digital control signals.  I think relay designs are generally bigger and more expensive than transistor designs, and can create additional electrical noise.

Maybe I've misunderstood your idea.  :-?

[Oliver]

Hi,

I would guess you could do the same design that you were thinking of, but use transmission gates instead of relays.  Do a search for 'transmission gate'.  There are other ways to tackle it, but I think this would match your original idea very closely.

You could have a look at this chip.  It has 4 transmission gates built in.  There should be a number of implementations, each of a '4066' designation.  The switch resistance is ~80 Ohms.  I think most relays will give much lower resistance than this, though.

I seem to recall there are also solid state relays available now (I've only used the electromechanical types).  I think internally, they are similar to photoconductors or MOS transistors.  These should be smaller, less noisy, and maybe have multi packaged designs, and presumably low activation currents.

Otherwise, you could have a look inside the remote control, and see what kind of signal is required internally.  Then, design the transistors to affect the signals as required.  This might be more of a hassle for you though.

edit- I haven't looked at this very closely, so take all the usual precautions.