[sdiy] Power Supplies

[Rob Spencer]

I'll do some testing when I'm next in the workshop, but from memory I don't think I've seen exactly 12v, plus or minus, on either rail. Plus heat will also have an effect on the voltages.

The op amp supply example probably wasn't the best example, but where a design has a voltage divider biasing an op amp, for example, it may have an effect.

I'll do some testing and have a look what's happening.

My main question was how I would increase the current using a power transistor?

Cheers

Rob

> On 10 Oct 2015, at 11:38, mskala at ansuz.sooke.bc.ca wrote:
> 
>> On Sat, 10 Oct 2015, Tom Wiltshire wrote:
>> What's the evidence that drawing more current from a linear regulator
>> causes its output voltage to fall? I thought that was exactly the
>> problem regulators were supposed to solve?
> 
> If the output voltage doesn't decrease when the current increases, then
> the real part of the regulator's output impedance is zero or negative,
> which is very likely to create stability problems.  You want to to have a
> small, positive, and almost purely resistive output impedance.
> 
> -- 
> Matthew Skala
> mskala at ansuz.sooke.bc.ca                 People before principles.
> http://ansuz.sooke.bc.ca/