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Newbie Project

Discussion in 'General Electronics Discussion' started by Gibran Gibran, Oct 4, 2016.

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  1. Gibran Gibran

    Gibran Gibran

    Oct 4, 2016
    Greetings all,

    My son 11 and I (the dad) decided to embark on this project while eating lunch at my friend's restaurant. The idea stemmed from the restaurant's POS system and the kitchen printer, an order is sent to the printer without any other indicators (blinky light or sounds).

    The printer is connected via an ethernet cable with an IP address, standard IP network. My thoughts were to insert a coupler between the printer and the network switch and with external magic to either a light or a buzzer. When an order is sent to the printer the cook is aware if he did not see the printer.

    Here's the problem, or problems. First I have no electronics background, but my 11-year-old love this stuff and we do simple projects with breadboards and Raspberry Pi :). The other problem is I am not sure if the voltage on ethernet cable changes depending on the amount of traffic is traversing the wire, this is something I need to confirm.

    Any suggestions, pointers, is this doable and where do we start?

    Thanks a bunch,

    Gibran and Gibran
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    One solution is to monitor the power to the printer. It probably draws more current as it prints. A fairly simple circuit could detect this and sound an alert.

    On the network you could sniff packets and sound an alarm when significant traffic is designed for the printer. The drawback here is that you may raise an alert if something interrogates the printer.
    Last edited: Oct 5, 2016
  3. Colin Mitchell

    Colin Mitchell

    Aug 31, 2014
    The best thing is to use a piezo to detect vibrations from the printer and turn on a 120dB siren for 5 minutes.
  4. Audioguru


    Sep 24, 2016
    Use a car alarm powered from a 12VDC wall-wart.
  5. AnalogKid


    Jun 10, 2015
    Your basic premise about sensing printer commands on the Ethernet cable almost certainly will not work without a significant programming effort. The "sniffer" mentioned above is a real thing, but not a beginner's project.

    There is constant Ethernet traffic going to the printer, and it is the internal NIC that decides what to use and what to ignore. Letting the printer handle this task and sensing the results is much less effort and a more reliable approach. As mentioned, you can sense a change in power draw, vibration, audio emissions, etc. Or you can open the printer and electrically sense current to the printer motor or some other internal signal that changes when printing. Make and model of the printer would help.

    davenn likes this.
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