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Need relay that operates with 3.8 VDC input.

Discussion in 'General Electronics Discussion' started by Sensor One, Jan 5, 2017.

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  1. Sensor One

    Sensor One

    1
    0
    Jan 5, 2017
    Hello,
    I have an input of 3.8 VDC and I am looking for a relay that I can use. I have seen only 5VDC relays and I am wonder if I can use the 5VDC using 3.8VDC as input.
    Thanks,
     
  2. Audioguru

    Audioguru

    3,114
    696
    Sep 24, 2016
    The datasheet for every relay shows its minimum pull-in voltage. I haven't used a relay for about 45 years so I cannot remember if it is a certain ratio of its nominal voltage.
     
  3. hevans1944

    hevans1944 Hop - AC8NS

    4,580
    2,142
    Jun 21, 2012
    If you can find 5 V somewhere (maybe the circuit from which your 3.8 V DC is derived) you can use it to power the relay through a transistor switch controlled by your 3.8 V DC. If the raw DC supply voltage is much higher than 3.8 V DC, you can use a relay with a higher coil voltage, still controlling it with a transistor. Either way, a diode across the relay coil is required to protect the transistor from coil back-emf that occurs when the transistor is turned off after conducting to energize the coil.

    You might also want to try this relay with a 3 V DC coil for reliable operation from 3.8 V DC, with or without a transistor switch.
     
    Last edited: Jan 6, 2017
  4. Alec_t

    Alec_t

    2,934
    799
    Jul 7, 2015
    What do you want to control with the relay? Have you considered using a solid state switch instead of the relay?
     
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