The PX13 mercury cell used to be common in lightmeters and for powering exposure meters in several diverse cameras. The MRB625 is a direct replacement and being Zinc/air it is almost environmentally friendly. The problem is this Wein Cell is the only direct replacement I have found and they are expensive at £8.00p a pop delivered. I got to thinking and borrowed a 675 hearing aid battery.  These are much smaller in diameter about 4.5mm smaller and their voltage is 1.4v as against 1.35v. I had a root through Ken’s big box of small “O” rings and found one that was about 2mm diameter… citeste mai mult