Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Electronics are a new area of interest for me (my skills lean toward
mechanical design and fabrication, although I'm relatively
comfortable with programming). A CNC project has forced me to dive
head on into this world, and I'm in need of some tips to start out.

For example, I have a need to route the output of my drives on the
basis of a three-position switch: e.g. "Off | Mill | Lathe".
When "Mill" is selected, one group of output terminals become "live",
when "Lathe" is selected, a different group becomes live.
I could almost handle this if all outputs were 5V TTL signals.
Unfortunately, only 7 of the 9 are. The other two drive the motor at
up to 80VDC @ 20A. This is clearly beyond simple signal switching,
and I don't have the experience in power circuit design to figure out
how to proceed.

Another, perhaps simpler puzzler for me is how to take a 17VDC, 4A
unregulated signal and produce both a 5VDC & 12VDC regulated signal
from it. Presumably, it's a matter of finding suitable voltage
regulator ICs, but even approaching a simple circuit like this
completely solo has me a little nervous.

I realize this forum might not be the right place to post such
questions, so what is the appropriate place? While I'm open to book
suggestions (and am plowing through a ton right now), I really
appreciate the human interaction and practical advice that are best
found on forums. Any suggestions? Are there professionals out there
who offer design services for simple stuff like this at reasonable
prices?

Thanks in advance for any tidbits you're able to throw my way.