Newby needs help with switching

Discussion in 'The Projects Forum' started by SteveB2108, Jun 10, 2009.

  1. SteveB2108

    Thread Starter New Member

    Jun 10, 2009
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    Hi, I hope I don't appear too dumb but I can't work out a solution to this (simple) problem.

    What I have is a mini 433MHz transmitter that I want to install in a panic button box. The panic button is a latching button (press in to turn on and twist to turn off) but the transmitter requires a momentary voltage to send a "turn me on" signal to the transmitter and a separate momentary voltage (on another pin) to send a "turn me off" signal to the transmitter when the latching button is released. So, there are 3 pins on the transmitter. One is common.

    I plan to use a 9V battery as the power source. The 433MHz transmitter will work betweeen 3v and 12v. Preferably I want to avoid draining the battery if the latching switch is left on.

    Any help with this design would be most appreciated. I am new to electronics so the more detail the better.:)

    Thanks
     
  2. hobbyist

    Distinguished Member

    Aug 10, 2008
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    56
    A oneshot multivibrator circuit, one for each of the 2 input pins, could be used.

    If the panic switch is a single pole double throw type.
     
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
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    Mostly speculation: Switch A,B,C; AC normally closed, when pressed mechanically latches to AB, in closing sends a +, 1ms pulse[ depending on input Z of transmitter] to ON transm. When switch is releaced, a pulse is sent to OFF transm. If momentary = 1ms, might work. To disable transm. if switch is not released the lower ckt added. Time delay, R5-C willcause a +pulse ORd with origional OFF pulse to shut off transm. When C charges to zenor diode break down V , sensitive gate SCR 2N5060 is triggered, The charge on C is dumped across R7,R8,& R9, giving a + pulse to transm.R5 should be as large as possible but still able to trigger SCR, as the delay cycle will continue untill SW is resft, battery drain is then R2 in parallel with R5 for a leak of around 5μA. It's a start at least.
    Some possible values: R1,R4, R8,R9 100k; R5 1-2M; R6 2X R5; R7 220Ω; C, about 1 μF/sec.[ 10μF ]., diodes 1N914 etc., un-labled cap another .01. R2,RR3 10M.
     
    Last edited: Jun 11, 2009
  4. Externet

    AAC Fanatic!

    Nov 29, 2005
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  5. koen

    New Member

    Jun 10, 2009
    1
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    Gibberish removed by moderator.

    Strongly suggested that the OP make replies in a more acceptable fashion.
     
    Last edited by a moderator: Jun 12, 2009
  6. SteveB2108

    Thread Starter New Member

    Jun 10, 2009
    3
    0
    Bernard said "To disable transm. if switch is not released the lower ckt added."

    I am not sure I understand the 2nd circuit. The 1st one seems simple enough but what would happen if the switch is not released?

    If the 2nd circuit is used, how does it connect to the switch?

    Thanks for the help.
     
  7. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    We need to know what the panic button looks like electronically. how does it deliver pulses to the transmitter, then maybe we can find a solution for the latch I was just speculatong on what it might look like.
     
  8. SteveB2108

    Thread Starter New Member

    Jun 10, 2009
    3
    0
    Thanks for the comments to date.

    The switch looks like the attached electronically. I hope its clear enough.

    Steve
     
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