Archived posting to the Leica Users Group, 1996/08/03

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To: leica-users@mejac.palo-alto.ca.us (leica-users)
Subject: Re: MR4 meters
From: ohtonen.2@swsgen01es.ntc.nokia.com (Ohtonen Pasi)
Date: Sat, 03 Aug 1996 21:54:51 +0300
Organization: Nokia Telecommunications


>From: "C.M. Fortunko" <fortunko@boulder.nist.gov>
>
>Frankly, I do not believe that any of the cameras using only a single
>mercury cell (SL, SL2, and M5) can be regulated. This is because there is
>not enough voltage to make a transistor work. I assume that the CL has a
>similar meter circuit to the M5, although it was made by Minolta.

For making the compensation work, it is enough, if there is one element
in the circuit that is not linear. It may be a diode or a non-linear
resistance such as a  light dependent resistor. Effectiveness of the
compensation is achieved both with the type of components used
and with correct design.
There are tradeoffs to make between meter accuracy, simple design,
power consumption, meter sensitivity, supply voltage and resistance to
battery wear.
I suppose the MR meter is a combination of simple components
and clever design. I'm waiting for your test results with great interest.

Best regards,

Pasi Ohtonen