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Electronic component type (what would do this?)

  1. Jan 30, 2016 #1
    I was going to make a modem uninteruptable power supply, and I was thinking (possibly over complicated) that I could have a relay with the solenoid that has a potential over the battery bank and the power supply, so there would be near zero volts potential when the power supply was on (and charge the batteries to the level of the supply ~12v), then when the power supply failed a potential of 12v or so would be over the solenoid and cause it to trip.
    I was wondering if there was a component that:
    When the input is a voltage, then the output is a open circuit, and when the input is open circuit, the output is a Short. Would there be like an Opto-coupler that goes open circuit when the diode is on?

    Or if there is a solid sate component that could do this all integrated, that I haven't thought of...
    Last edited: Jan 31, 2016
  2. jcsd
  3. Jan 31, 2016 #2
    charger ---Diode----Battery----Diode----Load
    charging circuit dimensioned for maintanence load of the battery
    or something like this
    http://www.ccareswa.org/resources/tips/061220.php [Broken]
    Last edited by a moderator: May 7, 2017
  4. Jan 31, 2016 #3
    yeah thanks, but I want to totally disconnect the battery from the load, while keeping it totally charged.
    I am also curious if there is a component that acts like that, like if there is an opto-coupler that is off when it's on and vice versa.

    Last edited by a moderator: May 7, 2017
  5. Jan 31, 2016 #4
    You wanted first an uninteruptable power supply and now it should be totally disconected? o0) You should know what You want.

    The Diodes in the link disconect either one line or the other line totally, as current does not flow back while charged. But when needed because of impact, current flows automatically to the load as You wanted first.

    Suplementary If You want to disconnect the battery while not loaded whats the sense of uninterruptable supply? You can introduce as many switches or relais or diodes You want to disconect whatever You want.

    The name of Your device that does that is diode or switch or relais and for some there are also more sophisticated electronic pendants as transistors and SCRs - use an image search engine and type something like "battery charger switch circuit"

    or use this link

    or consult a doctor - good reconvalescence!
    Last edited: Jan 31, 2016
  6. Jan 31, 2016 #5
    That's not what I meant, they're not mutually exclusive, I was intending on having a capacitor to bridge the small gap in time between the relay flicking over. I'm aware of issues with USPs that I'm trying to design around.
    And no, I'd be very surprised if there wasn't something much simpler like an opto-coupler with a NOT logic arrangement built in, however I'd like to know what other (higher rated) options there were, because I don't want to conceive capasitive or restive voltage dividers to drive a mosfets for something that should be simple for a solid state component now days.
  7. Feb 1, 2016 #6


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    what @scanvas is telling you is correct, You told us you wanted a UPS
    but what you then say, negates the purpose of a UPS

    NOTE carefully what the U in UPS stands for = Uninterruptible

    so do you really want a UPS or not ?

  8. Feb 3, 2016 #7
    Well if you have a capacitor to bridge the gap, the operation is still uninterrupted.
    I just wanted something that could recharge but wouldn't dissipate charge, I suppose it would look something like this:
    excuse simplicity and crudity.
  9. Feb 11, 2016 #8
    Sooo...no good?
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