This is a collection of real-time, theory-based
interactive simulations of some simple electronic circuits for
use by students in a course I
used to teach called "Electronics for Chemists" at the
University of Maryland College Park, which was basically a
laboratory course in elementary practical instrumentation
electronics. I used them as homework assignments, while
the students were constructing and studying these circuits
in the laboratory, in an effort to deepen their conceptual
understanding. A Macintosh computer lab in the building allowed
all students access to these programs, and, once the Internet
became available to the campus in the early 90's, they were also
available on-line.
One of the problems in teaching electronics is
the difficulty students have in moving back and forth between
the static, two-dimensional symbolic representations of
traditional schematic diagrams and the real, 3-dimensional
circuits in the laboratory. My simulations help to bridge this
gap by allowing the student to work with representations that
look just like the schematic diagrams in their textbooks, yet
actually work and respond to changes just like the real
circuits. Using the mouse, you can drag sliders to control
voltages and resistances, open and close switches, and type in
the values of various components. The simulations use the laws
of electricity (Ohn's Law, Kirchoff's Laws, etc) to display
voltages and currents throughout the circuit dynamically in
real time as the sliders are moved.
Another problem is that so much is invisible. The
actual laboratory experiments show only the outer, macro-level
effects, leaving the student to imagine the inner workings such
as current flows and voltages changing at multiple points in a
circuit. Computer simulations can sometimes show these inner
workings in a way that real experiments can not. Still, these
computer simulations were not intended to replace
laboratory experiments and real-world experience, but rather to
extend and augment
textbook treatments. Real circuits display a host of other
effects that are not included
in these simulations, such as overheating, burnout, component
failure, poor shielding and grounding, intermittent and unstable
connections, noise, drift, and stray pickup.
Instructions
These simulations do not run on the Web; they are
self-contained programs that can be downloaded and run on
stand-alone machines. They were developed in HyperCard for
the Macintosh in the early 1990s, but there are also versions
for PCs and Unix machines.
If you have a old Macintosh model, you can
download and run the original Hypercard stacks. They are very
small and require little computer power or screen space; you can
have several of the simulations open at the same time in
separate windows. They'll even run on the old 9" monochrome Macs
such as the SE or Classic.
Click here to download the complete set of ElectroSim 2.0
modules in ".sit" compressed format (570 KBytes), including the
Hypercard Player application. Stuffit Expander will
automatically decode and decompress the downloaded file into a
folder containing the full set of ElectroSim modules.
Double-click on a module to launch it, or drag and drop it onto
the Hypercard Player.
PC users and others can run these
simulations via the free downloadable Revolution
Dreamcard Player, which is available for several
platforms. To download the complete set of ElectroSim modules
for a Windows PC, including the player, right-click on
this link and select "Save Link As..." to begin the
download (5.5 MBytes) to your PC. Then right-click on the
ElectrosimRevolution.zip file and select "Extract All...". Open
the resulting ElectrosimRevolution folder and install the
Dreamcard Player by double-clicking on
"dreamcardplayersetup.exe" and following the on-screen
instructions. Multiple simulations may be open at one time.
Thanks to Phil Odor (jpodor@f2s.com) for his excellent work in
converting my Hypercard stacks to Revolution Dreamcard format.
If you have trouble installing the DreamCard
player, you can also run these simulations with the free StackRunner
from http://www.sonsothunder.com/devres/livecode/downloads/StackRunner.htm.
Open each simulation by right-clicking on the
corresponding *.rev file in the ElectrosimRevolution folder and
selecting "Open with..." > "StackRunner...".
Multiple simulations may be open at one time.
On the left side of each simulation module
is a panel with several icons. Click on: 
"What do I do?" for quick instruction for that module.
"Explain" to pop up a series of text boxes that explain the
circuit operation (click again to hide the boxes).
"Show current flow" to see an animation of current flowing.
"Show
specs" to inspect and edit the transistor's characteristics.
Click this icon to view the next
simulation. Click this icon 
to return to this index page.
"I found your site last week and have already started using it
in two of my classes."
"Very nice! I think I can find good use for this at work, in
some basic electronic demonstrations during staff training."
" ... lots of useful stuff."
" ... your pages really helped."
"I have found your interactive simulations of basic
electronics extremly interesting."
" ...I'm writing to offer our thanks for your Hypercard models.
The transistor models have helped us dredge old knowledge back
to the surface...."
ElectroSim 2.0
This page was created
by Prof. T. C.
O'Haver , Department of Chemistry and Biochemistry, The
University of Maryland at College Park. Comments, suggestions and
questions should be directed to Prof. O'Haver at toh@umd.edu.
First version created in 1996. Last updated November 2013.