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Electronics Make me a circuit to fire a +12v pulse when data is sent down the serial port

Discussion in 'Modding' started by xen0morph, 3 Dec 2008.

  1. xen0morph

    xen0morph Bargain wine connoisseur

    30 Jun 2002
    Likes Received:
    Hi all,

    I need a circuit - as simple as possible - to fire a momentary 12 volt pulse when data is received on the RS232 port.

    I don't mind using an external power supply, and it doesn't matter which data it actually is - basically if anything is sent down the serial port (using ECHO TEST>COM1 in DOS for instance), I want a 12 volt pulse to come out.

    What's the easiest way to do this?

  2. mvagusta

    mvagusta Did a skid that went for two weeks.

    24 Dec 2006
    Likes Received:
    When data is being transmitted on the serial port, there is going to be a heap of pulses on the data lines. You can use the data as a trigger to drive whatever you want via a transistor or some sort of gate and then up to anything else for example, but i'm not 100% sure if this will interfere with the communication of devices... i don't think it will, but i don't know alot about serial ports, maybe others have knowledge in this area?

    And do you just want a single 12v pulse to happen when data begins? And if so, how long before the circuit is reset, to detect the next pulse? Or should it be manually reset instead of automatic?
    Or do you want a 12v pulse for each an every bit of data that recieved?

    If you further explain what you are trying to achieve you'll probably get better feedback.
  3. cpemma

    cpemma Ecky thump

    27 Nov 2001
    Likes Received:
    There's one way of interfacing shown here. Not the simplest, but it has good protection of the serial port through the opto-isolator. The output end design (where they use a 5V hex inverter) depends on what you want to do with the 12V pulses - current needed, duration, etc.
    mvagusta likes this.

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