The Museum of HP Calculators

HP Forum Archive 06

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Re: HP71Voltages
Message #1 Posted by Tony Duell on 7 June 2001, 4:41 p.m.

According to the manuals I have (HP71 Hardware IDS, for example), it's not a 3 terminal regulator, it's a simple NPN power transistor. It's used in the standard zener diode + emitter follower circuit, and it's the zener diode that sets the output voltage. The transistor is not that critical. Alas the parts list in the manual simply calls it a 'Transistor, NPN' -- no equivalent is given. But I think that just about any small power transistor should work.

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