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    • February 14, 2020 7:01 PM EST
      • Southern Oregon
         
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      14 volts

      Hey guys,

      What is the easiest way to get 14 volts using two 9 volt batteries?

      Thanks for any input.

    • February 14, 2020 8:08 PM EST
      • Candlewood Valley, Connecticut
         
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      A diode in series will drop 1.5 Volts. Add them up to get the drop you need.  Some current is lost in the process.

       

      EDIT to add: Your batteries go in series, along with the diodes.

      This post was edited by Jon Radder at February 14, 2020 8:09 PM EST
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    • February 14, 2020 10:42 PM EST
      • Santa Ana, CA
         
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      Jon Radder said:

      A diode in series will drop 1.5 Volts. Add them up to get the drop you need.  Some current is lost in the process.

       

      EDIT to add: Your batteries go in series, along with the diodes.

       

      A diode in series is typically about a 0.7 volt drop.

    • February 15, 2020 7:34 AM EST
      • Eastern Massachusetts
         
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      There are different types of diodes, some drop .3 volts.  And 9 volt batteries are 9.45 volts when fresh.  lead acid batteries are never an even voltage output.  Cars are 12.6 volt batteries, not 12 volts even.

      You could use the LM317 device and I did assume low current and these are available as 100ma or 1.5 amp.  LM350 is 3 amp.  They only draw the load plus 4 ma.

      Note you need up to 3 volts more than the voltage programmed and fresh 9 volt batteries are more than 9 volts so 2 in series are over 18 volts/ almost 19 volts.

    • February 15, 2020 7:46 AM EST
      • Candlewood Valley, Connecticut
         
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      Todd Brody said:
      Jon Radder said:

      A diode in series will drop 1.5 Volts. Add them up to get the drop you need.  Some current is lost in the process.

       

      EDIT to add: Your batteries go in series, along with the diodes.

       

      A diode in series is typically about a 0.7 volt drop.

       

      Thanks Todd. Memory is failing; I probably used two for my 1.5V drop

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    • February 15, 2020 10:35 AM EST
      • Southern Oregon
         
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      Thanks for the info guys, all I have to do now is figure out what it means

      I'm just lighting one 14 volt bulb so I want to be just a little under the max volts to prolong bulb life..

       

    • February 15, 2020 10:52 AM EST
      • Vail, Az
         
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      Get a 12v wall wart to supply it, won't be the brightest, but will last.

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      John

       

      The older I get, the less I know, please don't make me prove it.

       

       

    • February 15, 2020 11:16 AM EST
      • Gig Harbor, WA
         
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      Rick,

      Does it need to be an incandescent bulb or could you use a led?  

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      Paul Burch

      Sierra Cascade & Pacific RR

    • February 15, 2020 6:51 PM EST
      • Southern Oregon
         
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      John

      What is a wall wart?

       

      Paul,

      Yea I could go the LED route but I prefer the color and look of the 

      bulb for headlights.

    • February 15, 2020 7:24 PM EST
      • Vail, Az
         
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      Wall warts are the plug in transformers that are very common now days, I have them all around the house and dang if I know what they are for... 

       

      Wall-Mounted AC Adapter - 12 VDC Power Supply - 12-36W

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      John

       

      The older I get, the less I know, please don't make me prove it.

       

       

    • February 15, 2020 7:31 PM EST
      • Southern Oregon
         
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      Ahhh, now I know what your speasking of, unfortunatly I don't think that will work in my application.  

      Did I forget to mention that this is for the headlight in my snowplow build

      But maybe with a long enough cord, hmmmm

    • February 15, 2020 7:37 PM EST
      • Vail, Az
         
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      Ah yes ...No.

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      John

       

      The older I get, the less I know, please don't make me prove it.

       

       

    • February 15, 2020 7:48 PM EST
      • Candlewood Valley, Connecticut
         
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      Try the bulb on one 9V.  You may be surprised that it gives a proper glow for an old light; and you will lengthen the life.

       

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    • February 15, 2020 7:50 PM EST
      • Eastern Massachusetts
         
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      Now knowing more info, why not just use a single 9 volt battery and a 20ma led.  Use the cl2n2 device to limit current to 20ma and voltage will not matter when the battery starts to fall down to 6 volts, the led will stay bright..  Also due to 20 ma the battery will last a lot longer!!

       

    • February 15, 2020 7:50 PM EST
      • Eastern Massachusetts
         
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      Now knowing more info, why not just use a single 9 volt battery and a 20ma led.  Use the cl2n2 device to limit current to 20ma and voltage will not matter when the battery starts to fall down to 6 volts, the led will stay bright..  Also due to 20 ma the battery will last a lot longer!!

       

    • February 15, 2020 7:55 PM EST

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      Rick Marty said:

      Hey guys,

      What is the easiest way to get 14 volts using two 9 volt batteries?

      Thanks for any input.

       

       

      Would have been easier if you wanted 13.5 volts!

       

      NO.. you have to make things difficult!

    • February 15, 2020 7:59 PM EST

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      Rick Marty said:

      John

      What is a wall wart?

       

      Paul,

      Yea I could go the LED route but I prefer the color and look of the 

      bulb for headlights.

       

       

      Shave the LED and diffuse it for color .....BTW clear LED's love sharpie colors like yellow and orange.

    • February 15, 2020 10:03 PM EST
      • Southern Oregon
         
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      Well to confess, I bought a package of 100, 14 volt bulbs from Alliance about 10 years ago, and still have about 80 of them left And I just hate to waste anything sooooo trying to use the bulbs

      Also I do like the look and affect of a bulb behind the glass lens.

       

       

      Dan,

      Thank you very much but the only word I really understood in your post was battery

    • February 16, 2020 8:22 AM EST
      • Eastern Massachusetts
         
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      Rick, the 9 volt batteries will not last long with the 14 volt bulbs, so it may be less dollars in the long run to use rechargable, depending of course on your run times.

    • March 12, 2020 3:02 PM EDT
      • Westborough, MA
         
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      Hi Rick,

       

      I assume those bulbs draw about 175mA, is that about right?  With any linear dropping approach, like a primitive diode string, or a linear voltage regulator, you're not going to get much life out of a pair of (relatively expensive) 9V batteries.  With a linear regulator like an LM7317 your setup will quit about 1/2 way through the batteries' life (about 8.5V each), and at that draw will only last a couple of hours.

       

      A much better approach is to use a small, switching, step-up converter, which you could run from one 9V battery, or any pack of 2 or more volts, and adjust the output to exactly 14V.  It will hold this voltage throughout the life of the batts.  It will run at greater than 90% efficiency.  

       

      Such a device is available on eBay for under $1 with free shipping from China (under 50 cents if you buy five), or under $5 from a US source.  

       

      Search for SX1308.

       

      Regards,

       

      jv

      This post was edited by John Visser at March 12, 2020 6:26 PM EDT
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