hooking 12v telegraph to walkie talkie

Discussion in 'The Projects Forum' started by cwtelegraph, Dec 22, 2010.

  1. cwtelegraph

    Thread Starter New Member

    Dec 22, 2010
    2
    0
    Here is what I'm looking to do..

    I have a KOB wired telegraph that runs off a 12 volt tractor battery
    (use for civil war reenactments)

    I want to eliminate running wire to operate the system but still make it look authentic for the 1860's by using the electromagnetic sounder and key.

    is there a way (possibly using a relay in a "black box") to have the key activate the send on a walkie talkie or family chat radio on one end and have the signal on the receiving radio convert the signal back to 12 volts to activate the electromagnetic sounder (sounder is 8 ohms)

    I would need to switch sending and receiving on both ends so communications could be had (with the apearance that a wire is actually run between the telegraph stations.

    Not sure what type of relay I would need, nor where I would wire into the radio (walkie talkie/ family chat radios) that would allow the relay to operate.

    Any help or suggestions how I can do this would be helpful.

    As with anything- cost is also important

    Thank you in advance for any and all suggestions!
     
  2. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    Keying the transmitter is going to be the easy part. At the receiver end all you have is a dead carrier. On the other hand if the HT has a squelch pot and the speaker makes white noise when a signal is absent, you may be able to utilize the absence of white noise (quieting) to drive the interface to the sounder.
     
  3. cwtelegraph

    Thread Starter New Member

    Dec 22, 2010
    2
    0
    Thats what I was kind of thinking of tring to do.

    Using the walkie talkie or family chat radio by

    keying the transmitter with the talk button.

    and on the receiver side with the speaker

    What I don't know is what type of relay would work to convert the 12v sounder to circuit to close the circuit to transmit

    as well as to hook to the speaker on the receiver end to close the 12V circuit to activate the sounder on that end

    I would just hate to rip apart a set of radio's to find out it won't work or just burn them up on the first try.
     
  4. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    Before you tear into these radios and go any further in this thread insure the following:

    (1) If the radio has PL or DPL squelch insure that this feature can be turned off and that it will work in a basic noise squelch mode. A pure noise squelch will produce a steady and quite loud white noise when the squelch control is adjusted below threshold and a carrier is absent.

    (2) These HT-s are quite small and rarely have any visible hardware that give clues to how it's opened. Most of them have hidden plastic snap tabs that are pried open but you need to know where they are.

    (3) Since they're very small you will need good soldering skills to tap into the PTT circuit.
     
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,779
    932
    make a little one transistor wein bridge osc, and send an audio signal.(4000Hz would be a good number)

    Rectify the AC wave at the reciever and use the output to drive the keyer, or if it is to low current use it to trigger a transistor to drive the keyer.
     
  6. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    Yes, he could do that but he won't need it if the radio can be switched to noise squelch.
     
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