Sending & Receiving a sync pulse on top of a DC power supply rail.

Discussion in 'The Projects Forum' started by dkinfo, Dec 30, 2014.

  1. dkinfo

    Thread Starter New Member

    Dec 30, 2014
    I would like to send a single sync pulse "on top of" a 12V DC power supply rail. The pulse would be in the order of 500 nSec - 1 uSec at a 5- 10 kHz rate. Capture.JPG
    I would use this pulse to synchronize devices connected to the +12V power rail. My first questions would be, how do I "put the signal on" and "get it back off"?

    Would detecting the pulse be as simple as this: (VRaw is the +12V Rail with pulse, the divider scales the level to roughly 3.3V TTL and R10 limits the current to the target device.)

    As Captain Ramius says in "The Hunt for Red October": " Give me a ping, Vasili. One ping only, please."

    I do not need an extensive communication network, just the ability to sync several discrete devices meters apart at the same time. I am worried that this pulse also switches the DC energy being used at the time, somewhere in the order of 4 to 5 Amps. Is there another simple (read not many parts) method of placing and recovering a sync pulse on a DC rail?

    Thanks in advance for your ideas and comments.

    Happy New Year!
  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
    You won't need the voltage divider to pick off the pulse, just the capacitor and possibly R10.

    How you introduce the pulse depends on the design of the power supply i.e. It may be possible to achieve it within the PSU but, if not it, would have to be done externally.
  3. nerdegutta


    Dec 15, 2009
    That is a great movie. :)
  4. MrChips


    Oct 2, 2009
    How do you drive a signal into a 100mΩ load?
  5. MikeML

    AAC Fanatic!

    Oct 2, 2009
    You put a choke (inductor) with low dc resistance between the power supply and where you inject the signal. You might have to put chokes at the receivers, too, to keep the signal from getting swallowed by the power supply bypass caps in the receivers.