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Regulate from 12v to 3v?

Discussion in 'General Electronics Discussion' started by Crogdor, Nov 14, 2015.

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  1. Crogdor

    Crogdor

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    Jun 7, 2013
    I'm working on a little project to wire up my garage door remote to trigger when I flash the high beams on my motorcycle. My garage door remote is a small fob containing a 3v coin battery (DL2023) and a single button.

    I've bridged the connections of the button, so it's always on now. The challenge I'm facing is that I don't know how to get the voltage from the motorcycle's high beam wire (12v) down to 3v. I have one of these buck regulators:

    Pololu 5V, 300mA Step-Down Voltage Regulator

    But that only goes down to 5v. I thought of using a voltage divider, and figured out the resistors with an online calculator, but then I read that a voltage divider is a bad solution because the resistance will change when it's in operation.

    Pololu also makes a 3.3v regulator (I've seen many other 3.3v ones, but no 3v). I think 3.3v is probably still too high?

    What is my best option here?
     
  2. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    22.jpg


    [pic edited my Mod]
     
    Last edited by a moderator: Nov 15, 2015
  3. Tha fios agaibh

    Tha fios agaibh

    2,143
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    Aug 11, 2014
    Or, LD1117V33, or lm7803?
     
  4. Martaine2005

    Martaine2005

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    May 12, 2015
    Hi Crogdor,
    Tha fios agaibh has the answer for your existing 5v regulator. Put a lm7803 regulator in circuit too.
    Or use the 3.3v regulator and put a shottky diode in series to drop the .3v.
    Either way will work.

    But you don't know if your key fob will cause other problems by being constantly activated. You could kill that circuit within a very short time.
    Or funnier still, see hundreds of garage doors opening in your rear view mirrors!!:p

    Martin
     
  5. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    If you're loosing sleep over 300mV,.. don't. It's not significant enough.

    Chris
     
  6. Bluejets

    Bluejets

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    Oct 5, 2014
    I believe the idea was to power the fob from the high beam as it was flashed on.
     
  7. AnalogKid

    AnalogKid

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    Jun 10, 2015
    The coin cell can be 3.6 V, so 3.3V is right in the middle of a good range for anything powered by one. 3.3V is a common power regulator output value because it is one of the standard power voltage values for newer digital logic chips.

    ak
     
    Martaine2005 likes this.
  8. Martaine2005

    Martaine2005

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    May 12, 2015
    Oops, oh yes...
    Still be fun to go down the street flashing.........huh........:cool:

    Martin
     
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