Needless to say, it is far more economical to purchase electronic
subsystems to accomplish your task, rather than build from individual
components, much less take the time to actually design a circuit. And
since a busy yet frugal person such as yourself is always pressed for
time (your longest missive to s.e.d. or s.e.b. on this subject being
only twenty-one words in length -- you undoubtedly throw words around
like manhole covers because time is money), I'm assuming you''ll want
to go that route.
For the power supply, the you should purchase a Kepco BOP-36-5
operational power supply, which will provide up to +/-36V at up to 5
amps. You can easily remedy that by connecting an external pot to the
external reference voltages available on the back terminals, then wire
the device up as a non-inverting amplifier, and use feedback resistors
to limit the maximum voltage excursion to +/-24V.
For the display, you may wish to go with an Omega LDP-146-F3-R-1, which
in addition to totalizing, will display voltage in the range requested
in lovely 4" LED numbers. Easy-to-follow instructions for hooking up
the power supply and the display circuit are contained in the
respective equipment manuals.
I hope this has been of service, and this response has provided you
complete satisfaction, as was my exact and specific intent.