[sdiy] Voltage Regulators

[Ian Fritz]

At 01:15 AM 10/17/2008, Oakley Sound wrote:
> > Any opinions on LM317 vs LM723?
>
>I'll echo Ian's point of view on a good distribution being probably more 
>important than the mV detail of supply regulation. However, the one 
>advantage of the 723 and series pass transistor is that you can set 
>maximum load current pretty accurately - you can also give it some sort of 
>foldback protection if that is what is required.
>
>The three terminal types have some bizarre and often unspecified 
>behaviours under shorted conditions. For the standard 7805, a 1A device 
>will often take over 1.7A under shorted or near shorted conditions. It'll 
>shut down when the die temp exceeds 150C of course, but that could take 
>some time with a big heatsink. I've not tried a 317 in this same sort of 
>test, but I would guess that the maximum current draw could be 
>considerably more than your transformer is rated for.
>
>Also, the 723 can be configured for remote sensing which is useful if your 
>power supply is in a different box to the distribution set up.
>
>Tony

All good points.  This is just a matter of personal choice, but I use a 
large, central raw DC supply, which fans out to several cabinets, each of 
which has local regulators.  This keeps most of the digital hash fairly 
well localized plus I don't have to run the regulators real hot. And there 
is only one line-voltage connection, well away from the cabinets. The 
central supply is on a large chassis, where I can add more transformers, 
caps, rectifiers as needed.

   Ian