Low voltage relay??????

Discussion in 'General Electronics Chat' started by zeeshan007, Dec 31, 2011.

  1. zeeshan007

    Thread Starter New Member

    Mar 27, 2010
    4
    0
    HI, i m working on my semester project of password proected door lock using 4 bit comparator... when the two inputs or enterted combination and pre-set combination match, the comparator will send a high value of about 2V at its A=B port. i want to drive a relay using this low 2V voltage to trigger high voltage of about 12V. but i dont think so any relay exist that can work on 2V (Vmin = 5V is necessary to drive a relay).

    So i need a model number of relay or Solid state relay that can trigger high voltage using low voltage of 1.8 or 2V....

    i will be very very thankful if someone help me.....
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    Just use a transistor to drive the relay. A general purpose NPN such as a 2N2222 should work. Be sure to add a transient suppression diode across the relay coil (cathode to plus side).

    How much current is available from the 2V output?
     
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  3. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    What technology of comparator are you using? 2V is a very low level. A schematic of your planned arrangement would help people to advise you.

    Depending on how much current the comparator could supply, a bipolar transistor or an very low threshold FET might be suitable.

    Typically SSRs require some milli-amps of drive current. Their actual input voltage may not be much more than you describe, but for consistent operation they are normally run from a voltage via a current limiting resistor.
     
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