Re: [Leica] M6 electronics

["Don Ferrario" <don@ferrario.com>]

Ken,

I believe what you are describing is a simple
voltage regulation circuit.  The "ram chip" is
probably just a simple diode.

This is necessary because the battery voltage
changes as the battery gets old.  The cameras
from the 60's that used mercury batteries
did not have voltage regulation.  That was possible
because mercury batteries have an almost
constant voltage output, up to the time they
die completely.  Later batteries (alkaline, etc),
have a more gradual drop-off in voltage.  This gives
the operator more warning that the battery is getting
old, but of course it changes the reading of the
light meter.  

The voltage regulation circuit corrects for this problem.
The simple printed circuit you saw is just another form
of wires to connect the pieces. 

I don't have the exact dates handy, but I believe
printed circuits were invented in the 50's, and
solid state diodes were from the very early 60's.

Therefore, you can rest easy - your M6 does NOT have
a computer chip inside.

don ferrario

- -----Original Message-----
From: Ken Wilcox <wilcox@umcc.umich.edu>
To: leica-users@mejac.palo-alto.ca.us <leica-users@mejac.palo-alto.ca.us>
Date: Sunday, June 28, 1998 5:30 PM
Subject: [Leica] M6 electronics (was Leica and 15 year...)


>I have a complete meter circuit in front of me. I'm not an electronics
>expert but I'll describe what I see and perhaps the experts can identify
>the parts.
>