Difference between revisions of "PX625"

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The '''PX625''' (also referred to by other names such as PX13) is a small button-shaped 1.35 volt [[Mercury Cells|mercury battery]], whose case has a wider lip surrounding its negative pole.
 
The '''PX625''' (also referred to by other names such as PX13) is a small button-shaped 1.35 volt [[Mercury Cells|mercury battery]], whose case has a wider lip surrounding its negative pole.
  
Before the manufacture of mercury batteries was banned, A great number of cameras and light meters were designed to use PX625 cells. Mercury batteries produce a constant and reliable voltage, so light meters were often designed without any voltage regulation in their circuitry. Use of other battery chemistries (such as alkaline or lithium) do not provide the same constant voltage, and will give erratic meter readings and exposures unless preventative measures are taken.  
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Before the manufacture of mercury batteries was banned, A great number of cameras and light meters were designed to use PX625 cells. Mercury batteries produce a constant and reliable voltage, so light meters were often designed without any voltage regulation in their circuitry. Use of other battery chemistries (such as alkaline or lithium) does not provide the same constant voltage, and will give erratic meter readings and exposures unless preventative measures are taken.  
  
 
==Devices requiring PX625==
 
==Devices requiring PX625==

Revision as of 14:20, 11 August 2011

The PX625 (also referred to by other names such as PX13) is a small button-shaped 1.35 volt mercury battery, whose case has a wider lip surrounding its negative pole.

Before the manufacture of mercury batteries was banned, A great number of cameras and light meters were designed to use PX625 cells. Mercury batteries produce a constant and reliable voltage, so light meters were often designed without any voltage regulation in their circuitry. Use of other battery chemistries (such as alkaline or lithium) does not provide the same constant voltage, and will give erratic meter readings and exposures unless preventative measures are taken.

Devices requiring PX625

Many cameras and light meters were designed for and require a 625 mercury cell: list of cameras and list of exposure meters. Some cameras and exposure meters were designed for 625 sized cells but include voltage regulation circuitry and thus do not require a PX625 to function properly (list of devices), and so can use the higher-voltage (and less voltage-stable) alkaline (PX625A, 1.5v) or Silver-Oxide (S625PX, 1.55v) cells. Devices without regulation circuitry (or some method of compensating for other voltages) can use Zinc-Air type cells made especially - with the correct 1.35v potential - to replace the mercury cells.

External links

  • Suggestions from Rick Oleson (based on ideas from Leon Schoenfeld) to make classic cameras give acceptable meter readings using modern alkaline batteries.
  • The mercury cell problem and its solutions (PDF file) by F. de Gruijter. Also discusses PX675 and other mercury batteries.
  • Notes on using zinc-air hearing aid batteries to replace mercury cells part 1 and part 2 from Silverbased
  • The mercury oxide battery problem, at Konica SLR system, providing information about the PX625 and PX675 battery that is not specific to Konica models
  • VintageBatteries.com Seller of mercury replacement batteries including the WeinCell MRB625, a zinc-air replacement for the mercury PX625.
  • My Old Camera Source for 1.35 volt PX625 mercury replacement batteries that use zinc-air technology to acheive a steady 1.35 volts