The Pentax Spotmatic series may all be ok (when they use a bridge circuit with Silver Oxide or alkaline batteries).
Originally Posted by wiltw
The Pentax K1000 series ditto (they use a dual coil galvanometer for similar effect)
But I'd use silver oxide in either myself, e.g. cept when stuck on Sunday, with dead battery and no shops.
The rest probably all need a Shockley diode to drop the Silver ovide 1.5 volts (nominal) to close to 1.33 volts.
Most of the time I remove battery and use sunnyside f/16...