Yashica TLR battery voltage and size adapter

thingiverse

I made this adapter for using an SR43SW silver oxide battery in place of the mercury battery for the light meter of Yashica TLRs (and maybe some other cameras with similar battery bays). The adapter has a slot on the bottom (minus) side for inserting a Schottky diode to step the voltage down from the 1.55-1.60V of the SR43SW to the 1.35-1.40V of the mercury battery that the mater expects. Insert the diode into the slot, with the cathode leg of the diode (the one on the stripe side) twisted inside the adapter and touching the minus side of the battery, and the anode leg of the diode twisted on the outside of the adapter and touching the minus contact in the camera. Make sure the two legs don't touch (in the photo, they look close--I may want to readjust it a bit to make them further apart). On my Yashica 12, I then fitted the holder inside the battery holder cap, screwed the cap in place, and the meter matched the metering app on my phone pretty much right on. The diode I was using was pretty fat. If your diode is thinner, you'll need to tweak the scad file or else add some hot glue to keep the diode in position.