[sdiy] Negative voltage references

Tom Wiltshire tom at electricdruid.net
Sun May 20 12:02:01 CEST 2012


On 20 May 2012, at 02:34, David G Dixon wrote:

> I use 79L05 all the time for -5V regulation, particularly with linearized
> 2164 VCA circuits.  It works great.  Those will source up to 100 mA (but
> they do get pretty warm at that current).  I only use bandgap references in
> VCO circuits.  I've never used the big 7905s (the ones with the big hunk of
> metal on the side) so I can't comment on those.  The 79L05 comes in a TO-92
> package.

As I said, I'd have used a 79L05 if I'd had one. The chunky 7905 isn't doing the job without enough current pulled out of it.

> What's it for, anyway?

I'm working on a digital oscillator based on the new PIC 16F1847. I need -2.5V to cancel offsets for bipolar CVs coming into the PICs ADC channels.

T.




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