Switch power based on pulsed signal

Discussion in 'Power Electronics' started by NRC, Dec 14, 2016.

  1. NRC

    Thread Starter New Member

    Dec 14, 2016
    Hey Guys,

    First post so please be gentle with me, I only play with electronics so I am probably being exceptionally stupid..
    I am trying to create a circuit to switch on and monitor a digital output from an outboard motor. I have three signals I can connect to:

    +12v power (permanently on)
    a signal which is only active when the outboard is running and has an output of 12V 50% duty cycle and frequency of between 50-1000Hz

    To save on power I wanted to detect and respond to the signal to then power up the circuit which would ultimately monitor the signal and send it via wifi (ESP8266) to the boats central PC.

    I thought that I could use a resistor and capacitor (sort of low pass filter) to generate a voltage from the pulse signal (if i understand correctly think this will give me a voltage or around 6V) to operate an analog switch such as DG419, but on rereading the datasheet I think that my overall current draw is too much for that.

    My next thought is towards a solid state relay with a 6V coil voltage, but after advice if there is a more straightforward or appropriate solution that I could deploy.
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    Welcome to AAC.
    How much current can the 12V 'signal' drive? If only low current then you could apply the signal via a diode to the gate of a MOSFET used as a switch for your circuit. A capacitor and resistor in parallel between the MOSFET gate and source would smooth the 12V.