Classic Computer Magazine Archive ANTIC VOL. 8, NO. 5 / SEPTEMBER 1989


Op Amp CAD

Super Disk Bonus designs circuits
by David Hayes

This month's Super Disk Bonus is Op Amp CAD, a tool for designing operational amplifier circuits. The integrated circuit Op Amp is the workhorse of linear amplifiers used in most audio equipment. Its low cost and high performance has made it the amplifier of choice among professionals, students, and hobbyists alike.

To use Op Amp CAD properly you need to have some familiarity with operational amplifier circuit design. This lengthy, but useful, BASIC program makes it cesy for you to experiment with different component values onscreen, because your Atari works out all the mathematical computations. Each time you enter a new value, the program works out new values for all the affected circuit elements. You'll see the results of each change immediately, and you can print out the values for reference.

This program was written by David Hayes of Huntsville, Alabama. Op Amp CAD requires an 8-bit Atari with at least 48K memory and disk. Op Amp CAD supports these basic circuit configurations -- inverting, non-inverting, Schmitt trigger, integrator, differentiator, and adder circuits.

Choose a configuration from the main menu and the program displays a complete schematic of the op amp circuit. Op Amp CAD then allows you to [SELECT] the design components, input new values, and instantly see the results. Some circuit configurations can be changed by pressing [OPTION]. To return to the main menu, press [RESET].

If your printer is on, the name of the circuit and the various component values will automatically be printed, as well as displayed onscreen. Turn off the printer if you don't want the values printed. This program should work correctly with just about any 80-column printer.

Help files are built into the program and can be accessed by typing [H]. Highly informative error messages also provide help. For example enter too low a resistor value and the program will warn you that you are risking a short circuit.

An extensive manual for Op Amp CAD is also on this month's Antic Disk. This manual provides detailed information on using the program and lists references for additional information on op amp design. If you are familiar with op amp basics, the program is so user-friendly it hardly needs documentation.


Op Amp CAD should be run from drive 1, on its own disk. To create an Op Amp CAD disk, first format a blank disk (Atari DOS command [I]) then write DOS files to disk (Atari DOS command [H]). Then use Atari DOS command [C] to copy all the files with one-letter and two-letter filenames from this month's Antic disk.

Files L, T, R, P, C, and W are Atari BASIC programs for Op Amp CAD. The rest are HELP files. Copy AUTORUN.CAD to your disk and rename it AUTORUN.SYS. Turn the computer off, put your Op Amp CAD disk in Drive 1, and turn the computer on-with BASIC. (XL/XE owners don't hold down [OPTION]). Op Amp CAD should load and RUN automatically.

Your September 1989 Antic Disk -- featuring Op Amp CAD plus a second Super Disk Bonus as well as every type-in program from this issue -- will be shipped to you within 24 hours after receiving your order. Just phone Toll-Free to the Antic Disk Desk at (800) 234-7001. The monthly disk is only $5.95 (plus $2 for shipping and handling) on your Visa or MasterCard. Or mail a $5.95 check (plus $2 shipping and handling) to Antic Disk Desk, 544 Second Street, San Francisco, CA

Files: All files in directory