Battery solution for FC

JonR

JonR

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I am tempted to bid on a FC in mint condition at an auction site here in Sweden. But what about battery replacements for the FC since the batteries it was built for was discontinued many years ago. Anyone using the FC and having found a good solution who can give advice !?

Jon
 
My Canon FTb and EF were designed for PX625 mercury batteries, 1.35V. I have adapters made by a Dutch engineer out of empty shells with a Schottky diode soldered around the periphery. When a 1.55V silver dioxide cell is put into the adapter, its output is reduced to what is needed. I understand there are similar but rather more expensive adapters available. One alternative which many adopt is to use hearing aid cells, though these have a rather short life. Possibly the best solution is to have the circuitry adjusted -- if it can be adjusted -- to work with silver oxide cells. Silver oxide cells, like mercury ones, have a flat discharge curve. The voltage of the commonly available alkaline kind begins at 1.5 but drops throughout its life, making it next to useless.
 
OK thanks - but is really the voltage that important. For the Electro 35 there is a voltage adjustment curcuit as far as I have understood it so it is quit OK to put in a 6V instead of the desired 5,6V. Since FC is a later model I would have guess that it had the same setup, or !?
Jon
 
Jon,

You should be OK with 6v as (I think) the circuit has a Wheatstone Bridge that provides a constant voltage to the meter. If the battery is the same size as the Electro, a SR44 with some sort of adapter to fill the length should work just fine.

PM me your address if you would like one of my home-made adapters.
 
John
Many thanks for offer but unfortunately this one does not take the same batteries as the Electro GS/GT/MG models - instead it was built for two PX640A batteries, unfortunately discontinued by Duracell in January 2000. That´s the reason for my question - I know how to handle the normal Electro 35´s and I have the Yashica-Guy-adaptor but this one is a different story....

http://www.yashica-guy.com/document/chrono2.html

/jon
 
Jon

You can get alkaline subs for the HgO 640a, if you need the 1.33V you can make an adapter to take a smaller AgO cell, which live inside the 640 case, you will need two such adapters.

Noel
 
Jon,

Ahh, the dreaded PX 640 - I can make an adapter to replace this one. I made one a while ago for Kim Coxon that (I believe) works quite well. It uses the SR44 as power source and puts out 1.35v at 200mA, so should work any camera or lightmeter. Discharge characteristics of the Silver-Oxide cell is quite flat, until it dies - similar to the original Hg cell.

The other alternative is the alkaline version, but you will have 1.5v and a very steep discharge curve.
 
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