IC Chip Bipolar Power Supply Q

[Paul Marossy]

I've been wondering about this for the last couple of days...

How does it affect a signal if an opamp running on a bipolar power supply is supplied with an asymmetrical voltage? In other words, what if you are getting +15 and -12.5? What does that do to your sound? Will it make it sound "mis-biased" or a little out of phase, or does it matter?

[niftydog]

would depend on the opamp in question, but best circumstance you would simply have asymetrical clipping.

[Paul Marossy]

Yeah, I guess the individual opamp's characteristics would come into play, wouldn't they? Asymmetrical clipping is cool. What would be the worst case scenario?

[Peter Snowberg]

Because the op-amp really doesn't see the "ground" potential, it won't care about the asymmetry at all. Normally, bipolar circuits will be biased at ground to get equal swing in both directions. If your supplies are not the same and you still bias at 0 Volts, you'll run out of headroom in one direction first but if your signals stay within the reduced headroom there should be no real difference.

You might want to adjust your Vref to be 1/2 of the V+ to V- span to equalize the headroom, or you might want to accept the asymmetrical clipping too.

I've seen lots of circuits that used -5 and +12 for the analog rails and either ground or +5 for the Vref. (older stand-up style arcade games)

Take care,
-Peter

[Paul Marossy]

Hmm... that's interesting. That makes things pretty clear, thanks.  

[smoguzbenjamin]

Stand-up arcade games... wow. I want a stand-up arcade game! :mrgreen:

[Paul Marossy]

Oh yeah. When I was in high school in the early 80s, they were everywhere. They had video arcades everywhere with Asteriods, PacMan, Space Invaders and too many more for me to remember. They are virtually extinct today thanks to the PC...

[RDV]

Dig-Dug & Frogger & Centipede & Robitron!!!

Blip

RDV

[Paul Marossy]

I also used to like a game called Space Duel.
And then there was Tron, which was pretty popular for a while.

[Peter Snowberg]

I had the board for Atari's Lunar Lander for a long time, but finally ended up loosing it. (it was a 6502 based machine)

Defender..... Pole Position.... Marble Madness....

Take care,
-Peter