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Voltage increase

Discussion in 'General Electronics Discussion' started by Tony P, Feb 24, 2013.

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  1. Tony P

    Tony P

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    0
    Feb 24, 2013
    I am new to electronics and have been messing around with 555 timers and 7 segment display drivers etc etc.

    I am currently trying to use an old remote control door bell circuit to set off a monostable timer.

    My problem is this:

    When activated, the remote circuit only sends out a 0.7v pulse to the sounder circuit.
    I would like to 'amplify' this pulse to approx 3v to trigger the 555 timer.

    Is this possible? Is this the way I should be looking at this or is there another approach?

    Many thanks in advance for any practical advice.
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    11,513
    2,651
    Nov 17, 2011
    Welcome Tony.

    One would like to know the schematic of that doorbell circuit.
    What voltage is present if the remote is inactive?
    A simple transistor switch might work. Read this.
     
  3. Tony P

    Tony P

    4
    0
    Feb 24, 2013
    Thank you for the prompt reply Harald.

    Unfortunately I do not have the schematic for the bell circuit.

    The circuit runs on 3v and there is a separate circuit board containing 7 led's that run in sequence for a visual output. This circuit has +3v, GND and a blue wire which I assume is the trigger (this is the wire that gives me the 0.7v pulse)
     
  4. EinarA

    EinarA

    28
    0
    Feb 11, 2013
    You can trigger a 555 with a small voltage if you couple it through a capacitor . At the input of the 555 use a pot to set the voltage to just below or above the threshold or tigger points, 2/3 and 1/3 of V+ respectively. Now the .7 V signal will push things over the line and trip the 555.
     
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