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The X-Philes (2nd Revision)
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The X-Philes Number 1 (1995).iso
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paral.doc
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1995-03-31
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Begin PARAL 1.4 Larry Hoppis Elinel Consulting
--------------------------------------------------------------------------
The following HP48 program contains general 1% resistor utilities for
electronics technicians and hobbyists. The main program 'RPAR' will
find all combinations of parallel 1% resistors to obtain the desired
value within a given accuracy. This is useful in case you don't have
the value you need on hand, but also because the exact value you want
may not be a standard off-the-shelf value.
:USAGE:
RPAR: Put the value of the resistance you want in level 1 of the stack
and press RPAR. RPAR presents a list of standard 1% resistance
values which when paralleled will yield the desired value. The
accuracy of each combination is also displayed. The required
accuracy is specified by the variable 'ACCU'. Pressing ACCU will
bring the accuracy value to the stack. Left-shift ACCU will
store the value on the stack into ACCU.
RPAR displays 9 solutions at a time using the small graphics
font. Pressing '+' (or any other key) will advance to the next
page. Pressing '-' will return to the previous page. Pressing
the backarrow key (unshifted DROP) will exit the program and
return the original value to the stack.
NXT: Given any value in level 1, will return the first standard 1 %
value which occurs above that value.
PRV: Given any value in level 1, will return the first standard 1 %
value which occurs below that value.
->PAR: Takes any two values in levels 1 and 2 and returns the parallel
combination of those two values to level 1.
DSP: Takes any value in level 1 decimal adjusts it for k or M
scientific notation and returns it as a padded string to level one.
->BIN: Takes any resistance value in level 1 and returns a bin number n
such that when n is a positive integer it represents the nth
calculated 1% resistance value (starting at 1 ohm). For example
if there were a numbered drawer for every 1% resistor value
->BIN would return the drawer number for a given value.
->VAL: Inverse of ->BIN. Takes any bin value in level 1 and returns the
value that would occupy that bin. If the input is an integer,
an exact calculated 1% value will be generated.
NOTE: Both ->BIN and ->VAL work with the _calculated_ 1% values
which must be rounded to 3 significant places to correspond
with standard 1% values.
TONE: Signal sound. You can copy this to your home directory, then
purge it; it is useful in other programs too.
THEORY: RPAR uses an equation I derived with the HP48 from a list of
valid 1% values. This list was also created on the '48 using
the formula
INV(96)
X = X*10 for all values between 1 ohm and 1 G ohm
0.0239852613838*X
The HP48 found 0.976300098965*e
This Equation and its inverse form the basis of ->BIN and ->VAL.
Similiar equations could be derived for other resistor series such as 5%
or 10 %. Utilizing these equations RPAR is accurate to at least 4
decimal places for all values from 1 ohm to 9.76E499 ohms - now that's a
big resistor! *:-).
COPYRIGHT
PARAL is copyrighted and may not be distributed for money under any
circumstance except in the case of a user group which may recoup a
small duplication fee. PARAL may be freely copied and distributed as
long as this original documentation remains with it. Please use and
enjoy PARAL and contact me with any suggestions or comments.
Larry L. Hoppis | quality!hoppis@ucscc.UCSC.edu | Love that '48!!
240 Azalea Ave.
Ben Lomond CA
95005 408-336-3651