fina

I am trying to wire a motion sensor (actually I belive it is a "beam break" sensor) to a portable Cd players remote control.
The idea is: someone walks by, breaks the beam the cd starts playing until done.
My intention was to wire it directly to the play/pause button on the remote but when I opened it up I found the button being mechanically triggered where a dome shape flattened out to make contact with an under lying outer circle.
Any ideas?

Nigel Goodwin

It's simply a momentary contact push switch, you simply need to arrange for a brief signal from your sensor - you might even find it works perfectly well with the button held down continually.

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fina

So if I glue the play button down and weld the wire to the momentary contact push switch, this should work?

Nigel Goodwin

?????

Just connect the contacts, preferably from a relay (to provide a floating switch, as it's probably multiplexed on the CD player), across the contacts in the CD player. The metal 'dome' is simply the moving contact of a switch, when you press it the 'dome' deforms (with a nice click) and shorts across the PCB, from the outer part of the 'dome' to the centre. You can't solder to there because it will prevent the dome switch working properly, just follow the PCB tracks to a clear area, and solder your two wires on there.

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Sebi

Be careful: this is a microprocessor input, not designed for long cable. 2...3m shielded cable should work, or use optocoupler to avoid disturbances.

-=GST=- Nemisis (cs/cz)

could u not have a NPN transistor to act as a switch and a schmit trigger to stop switch bounce? (although i should think the cd player has one built in) have a beam, when the beam break it gives an output (how u go about this is up to u) and the schmitt then resistor then NPN transitor?

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Nigel Goodwin

I suggested a small relay because the inputs will most likely be multiplexed, and not referenced to ground at all. Even if you use an opto-coupler, but you will have to ensure you connect it the correct way round for it to work - so such worries with a small relay.

If it's not a multiplexed input, and simply grounds an input pin, you could use a simple NPN transistor.

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PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

fina

The relay idea seems to be working, thanks for all your input