4066 usage

Discussion in 'General Electronics Chat' started by mscreations, Aug 6, 2010.

  1. mscreations

    Thread Starter New Member

    Dec 14, 2009
    I have a question regarding the usage of a CD4066 bilateral switch. I want to know if it is okay to use the switch to switch a completely different circuit without attaching any kind of ground or anything to the other circuit.

    Basically, I'm trying to override a switch in a door lock circuit. I don't know what kind of voltage is being switched by the existing switch, but I do know that it is a battery powered circuit supplied by a 9v battery.

    Here are the connections I am figuring for the 4066.
    Pin 1/Pin 2 - Wires to either side of the existing switch on the other circuit (these are the only connections I want to make to that circuit)
    Pin 7 - Ground from uC side
    Pin 14 - +5V DC from uC side
    Pin 13 - uC pin with 1k pulldown. I'll pull this up in software when I want to close the switch.

    Is this okay, or will I run into issues? I've been using a ULN2003 with a relay to perform the same job, but I would rather use the 4066 to reduce the power requirements (keeping the relay closed for too long zaps the batteries in my circuit too fast).

    Thanks for any help.
  2. marshallf3

    Well-Known Member

    Jul 26, 2010
    The CD4066 (and less commonly used CD4016) are outstanding devices that have come to my aid in many unusual situations. They're disgnated as quad bilateral switches but I like to think of them as an old crossbar switch in a telephony office.

    If I recall they'll work on signals without their common ground being present, however it would seem advisable to include some sort of ground reference for noise considerations.