Question: Building a Bi-Polar AC adapter

[Jason Myers]

I'm about to build a bi polar power supply to power some electronic
effects for electric guitar that I've built that I'm sick of putting
two 9v batteries in. The basic schematic and design is the one in the
Craig Anderton books. So, here's my first dumb question:
1. The power transformer should be mounted right on the chassis,
right? That's what I've seen in every other piece of equipment I've
poked my nose in, but I figured I'd get a second opinion here.
2. The voltage regulators I got from mouser (according to their tech)
require no heat sinks, as they're insulated with something. Is it a
bad idea to use these in a project that might be turned on for several
hours at a time? Should I get the "old" style regulators and use sinks
instead of these insulated ones? My concern is that while the
regulators may not be a danger to nearby capacitors, will they be
prone to shut down more quickly than the ones that require sinks? I'm
not going to put any caps too close to them anyway, but if anyone out
there has built this before mabye you could share your troubleshooting
experience with a less experienced builder.
Thanks in advance,
Jason Myers

 

[Art]

FWIW: I agree with your concerns and thoughts. I personally would go for the
older type of regulators and mount them appropiately on heat sinks using
transfer grease for each. Sounds as if you have most of the other factors
under control, just wondering what type of protection you are incorporating
into your product. Best to protect both the mains input and probably each of
the outputs. Good Luck

 

[Jason Myers]

Well, (for protection) I figured on using a heavy gauge wire for the
ground line and the supply lines, as well as building it in a
heavy-duty aluminum chassis, and, of course, one and only one common
ground point. Using heat shrink tubing on any exposed wire, especially
from the AC cable seems like a good idea. Also mabye running out of
the house fast as I can when I first turn it on, and carefully
re-entering if there's no smoke coming out.
Seriously, though, mabye I'll remove the insulator with a wire brush
and drill a hole in each one of the regulators and attach a sink to
it. Have you used these (new or old) regulators for anything? Do they
really heat up that much? Personally I haven't, so I'm curious about
that. Thanks for the tip!
Jason