Convert Repeating Pulse to Alternate Pulse

Discussion in 'General Electronics Chat' started by martinwinlow, Nov 20, 2011.

  1. martinwinlow

    Thread Starter New Member

    Nov 20, 2011
    Hi - Title might be a bit confusing.

    I want to make a series of 50ms pulses (0VDC low, 5VDC high appears to be a small SM transistor output so <50mA drive capability I would guess) alternately switch on 2 relays. So, pulse one switches on relay 1 for 50ms (or so), pulse 2 switches on relay 2 for the same time, pulse 3 switches on relay 1 for 50ms, pulse 4 switches on relay 2 for 50ms and so on.

    Anyone got any ideas? If it can be done all with relays, fine. Otherwise...?

    Regards, MW.
  2. SgtWookie


    Jul 17, 2007
    50mS is really too short of a time for a relay to respond - unless perhaps they are reed relays. It would probably burn the dickens out of the contacts.

    Why don't you describe what the overall concept is? At this point, it's sounding like you need a semiconductor solution, as electromechanical will be hard-pressed to keep up.
  3. thatoneguy


    Feb 19, 2009
    I'm guessing Christmas lights, but no load is given, or where the pulses are coming from, so it is impossible to guess.

    A quick digital solution would be put the pulses into a flip flop and your outputs being Q and !Q which would toggle.
  4. martinwinlow

    Thread Starter New Member

    Nov 20, 2011
    Hi - Thanks for replying and sorry to be so cryptic... It's really not a secret!

    The application is to use a modern Silent Gliss electric curtain timer/controller (5092) with their older system (9011) motors - these are fabulously well built but now obsolete. I currently have each my curtains working off a 2 way non-latching switch in each room. So to open the curtains you press the switch momentarily one way and to close them ditto the other way. This is all mains power switching. The motors also have a mains power supply direct to each motor.

    The motors can be low voltage switched too but not both mains AND low voltage.

    Apart from the mains wiring to each motor and motor switch there is a daisy-chain of CAT5 cable running from under the stairs where the service area is, to each motor wiring box (embedded in the wall behind motor & curtain) currently unconnected.

    What I was hoping to do was use SPDT relays switched by low DC volts with mains rated contacts to parallel (override) the manual mains switches, controlled by the 5092 timer to open (or close) all the curtains together.

    I can't get any info on what the output of the timer is or how it *should* be wired other than basic 'plug this plug into that socket'-type instructions from SG. However, I have managed (without destroying anything) to reverse-engineer the timer to the point where I can power it up. It takes 5VDC and uses an MCU and SM components into 2 RJ11 sockets, one is for the light sensor and the other for power and output. The power takes 2 wires leaving 2 for the actual switching output.

    I have measured the 50ms 5VDC pulses on one of the output wires every time either one of the Open, Stop or Close buttons on the timer is pressed. It also produces the same pulse on the same wire when one of the timed or light-sensed open/close events occurs. I am surprised it is not more complicated than that - at the very least an 'open' pulse on one output wire and a 'close' pulse on the other - which would make it very easy to do what I want. But as I say it seems to be both open, stop and close pulses are on the same wire, hence the need to 'separate' them. I will not need to stop the curtains but note that with the mains switches, if you initiate an open or close event, just by momentarily switching in the opposite direction it stops the curtains. So maybe it really is that simple.

    The flip-flop idea would work, wouldn't it? I'd just have to have a fairly chunky relay driver on the FF outputs...? Thanks agin for your interest.

    Regards, MW.