OA2s work much the same as Zener diodes but have a set of issues that I would think would make the Zener a preferred design means. One of them is that the tube makes noise when it fires (which is continuously) so you have to bypass them and isolate them from the regulator that is using it as a voltage reference.
Zeners make noise too but they are less problematic, plus you can choose zeners to make a variety of voltages. None of these issues present much challenge to a competent designer- consequently their use would be primarily for show (although they are functional) than anything else.
Zeners make noise too but they are less problematic, plus you can choose zeners to make a variety of voltages. None of these issues present much challenge to a competent designer- consequently their use would be primarily for show (although they are functional) than anything else.