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  1. #1
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    Annunciator Switches?

    Hello:

    I've been researching techniques for building annunciators for a 737NG sim and have a question about the type of switch to use.

    Most of the web articles I've seen on constructing these annunciators specify pushbutton or "tactile switches." When I link to the spec sheets for the switch parts specifically mentioned they specify these are SPDT Normally Open momentary switches or SPST Normally Open momentary switches.

    Don't I actually want to use pushbuttons that click on or off and not momentary switches? My understanding is a momentary switch that is normally open would only complete the circuit (and light the annunciator) only during the time when it is being depressed - not what would seem to be called for in this application. Sorry if this is an extremely basic question but I'm puzzled by the specific switches that are being recommended in some of these writeups.

    Also, can anybody recommend a favorate switch (manufactuer and part no.) for this application?

    Thanks for any help you might be able to provide.

  2. #2
    500+ This must be a daytime job
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    Hi

    If you are hard wiring, ie not using I/O software then yes you need switches that have a permanent state. However, I assume that you will be turning the annunciators on/off when a certain condition is met - this is generally done through the software controlling the input and output ports ( to which the switches and warning leds are connected). In which case momentary switches are fine, as the software will remember the state and keep the output live to an annunciator led until the warning condition changes, according to your programme.

    Regards

    David

  3. #3
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    makes sense when you factor that I/O info in. Thanks so much for that info.

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