<html> <TITLE>Longer Lamp Life</TITLE> <head> <!-- Styles for body, H1, P, fineprint, menu, etc. --> <link rel="stylesheet" href="../MyStyles.css" type="text/css"> </head> <body> <table width='100%'> <tr> <td width="25%"> &nbsp; </td> <td width="50%" style="font-family: Arial,Helvetica,sans-serif;"> Original Hint & Kink: <span style="font-size:Large; font-weight:bold;">Longer Lamp Life</span> &nbsp; QST February 1999 pg: 64 <br> <span style="font-size:smaller;">modified: 09/13/2012</style> <div style="font-family: Arial,Helvetica,sans-serif;"> </div> <br> <br> <span style="font-size:larger;"> <a href="../index.html#TXT"> Return to KE3FL WebPage </a> </span> <br><br> Back in the late 1970s early 1080s I was working as an Electro-Optics Physicist. I used to design devices with miniature halogen lamps. There was a family of equations that would give the life of a lamp dependent on its rated and operational voltages. I could not find the book these equations were in, so I looked up Welch Allyn and found the following: <br> <br> Welch Allyn = <b>http://hi-lux.com/minihalogen/tec.html</b> <span style="color:red; font-weight:bold;"> This URL no longer works. -09/2012 </span> <br> I found a new page. <br> <br> The information and equations we want are now located in the <b><a href="http://www.welchallyn.com/documents/Lighting/OEM_Halogen_Lighting/MC3544HPX_Catalog_2_11_09.pdf"> HPX Light Catalog </a></b> on Pg 7. Still titled, "Miniature Halogen Lamps-Electrical Characteristics" page, so select: Electrical Characteristics. <br> <br> Va = Applied Voltage &nbsp; &nbsp; Vd = Design Voltage <br> <br> <span style="color:#995577; font-weight:bold;"> Rerated Life = [Vd/Va]^12.0 x Life at Design Voltage *** </span> <br> <br> Rerated Current = [Va/Vd]^0.55 x Current at Design Voltage <br> <br> Rerated Candlepower = [Va/Vd]^3.5 x Candlepower at Design Voltage <br> <br> Now readers, who are interested, can calculate how long (in general) a de-rated lamp will last. <br> <b>(NOTE: A 12V lamp run at 11 Volts will last ~ 2.8 times longer.)</b> <br> <br> 72 & 73 de KE3FL Phil K Consulting Engineering Physicist <br><br><span style="font-size:larger;"> <a href="../index.html#TXT"> Return to KE3FL WebPage </a> </span> </td> <td width="25%"> &nbsp; </td> </tr> </table> <!-- Main table 100% width --> </body> </html>