Home Community

Help with using transistor as both N.O & N.C Relays

Author Topic: Help with using transistor as both N.O & N.C Relays  (Read 1008 times)

h3rman

  • Newbie
  • *
  • Posts: 1
    • View Profile
Help with using transistor as both N.O & N.C Relays
« on: March 31, 2013, 12:36:57 AM »
I made a circuit (the finished circuit is going to have many more "contacts") that is supposed to replace a bunch of relays.

Question no 1 - Does this work for the N.O function?

Question no 2 - How can i make an N.C. function? (I cannot use the 60 VDC as power supply. The N.C function must be working when there is no input voltage, and do to the place where the circuit is going to be i cannot use a separate power line or ground.

Hero999

  • Global Moderator
  • Electronics God
  • *****
  • Posts: 2603
    • View Profile
Re: Help with using transistor as both N.O & N.C Relays
« Reply #1 on: April 02, 2013, 11:07:45 PM »
The NC function generally needs a permanently live powersupply but there are ways round it.

The simplest way is to is to use a depletion mode power MOSFET or a JUGFET driving a BJT being driven by a small pulse transformer.

Another trick involves using a small battery to bias a transistor on and use an opto-coupler to turn it off.