It is possible it is a voltage divider, but it is also placed before the sub-circuit of the lamp, so I'm not sure this adjusts the voltage of the sensor. Probably the voltage to the lamp then?
@danj No it is not digital. It is the analog version with needle. Not much different from the 1-21 , except for the fact that 1-21 uses 2 batteries: 9V for low light measuring and 1.3 V mercury for bright light.(or vice versa perhaps).So the circuitry is also different. Spotmeter V uses only 3x 1.5 alkaline batteries (4.5V). I think the digital spotmeter is just called 'digital spotmeter'.The Spotmeter V has a grey casing.https://bwfilmdiaries.files.wordpress.co...
And indeed, there seem to be a black version as well, but mine is analog with needle.
And the bulb is incandescent, not led for certain. Because I'm looking for more information about it and a possible replacement, but it seems to be OEM.
My guess is that is comes perhaps from Honeywell as well, because Spotmeter 1/21 was made for Pentax by Honeywell in America, and perhaps my version also. Although this is pure speculation on my part.
I beg to differ about the model, mine has a needle, and the label on top says clearly Asahi Pentax Spotmeter V. But this one has as said, only one power source of 3 batteries, while the spotmeter 1/21 has two, and the circuit is different. You can check it on the site of Butkus: https://www.butkus.org/chinon/pentax/pen...
and https://www.butkus.org/chinon/pentax/pen...
And while I'm saying this, I notice that Butkus put a circuit diagram of the spotmeter 1/21 on his site.https://www.cameramanuals.org/flashes_me...
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