More on Fav Designs

[D. Schouten]

> Power Supplies
> ===========
> 
> It's hard to beat a 723/D40xxxx pass transistor. 
> 
> 8< Snip! 8<
> 
> What about switching supplies in analog designs? Too much voltage and
> current ripple?

Voltage ripple, i.e. 100/120Hz ripple, can be reduced to an absolute 
minimum in switch mode designs. Just a matter of good controlloop 
design.
Current ripple can be reduced with proper output filter design 
containing extreme low ESR capacitors. But there will always be a 
couple of mV's high frequency ripple on the output.

For symmetrical power supplies, you have to use hf-transformers with 
multiple secondary windings, and in general, only one output voltage 
can be fed back to the PWM. In that case there is usually some kind 
of post regulation on the outputs necessary too.

So to be short, using a switch mode power supply for DIY projects is 
just too expensive. Besides that, these things are pretty complex to 
design.  

Bye,

Daniel Schouten
SMPS designer at TBS Electronics