[Nemo de Monet]

I am, for kicks and giggles more than anything, intending to play around with a discrete preamplifier design from 1967 to see how well it may work as a headphone amplifier. I'm replacing the long-obsolete 2N404s with BD140s, and making a few other changes to allow the use of modern parts. One of the stranger things about the design is that it runs on a single-sided supply (I know, I know, boo hiss) - but a negative supply.

Now, they thoughtfully provided a power supply design, which is all fine and dandy, and while I understand how it works and what it does, I don't have any Zener diodes on hand, doh, but I do have a number of regulated power supplies in the appropriate voltage range. As long as they're isolated - which they are - is there any reason I can't just use a normal power supply here, albeit with the hot and ground leads inverted?

I mean, voltage potential is all relative, and "ground" is just an arbitrary concept here, right? And since it's capacitor-coupled, nothing should go terribly wrong if I cheat a little bit... right?

Crazy power aside - it feels very wrong to keep putting electrolytic caps on the breadboard with the "+" side towards "ground" - it seems like a moderately interesting design, and was alleged to measure pretty decently way back in the day....

 

[jcx]

schematics are meant to be understood by us, conventions make the job easier

current flow from Vplus at top to Vneg at bottom is pretty universally accepted today

now we rotate the PNP Q sysmbols


it is correct that with a isolated supply we get the chance to put the "gnd" symbol on any (one) node we choose