The device depicted here was my best shot at a solution. It's an
interactive realtime simulation of the behavior of charges within a wire.
Rather than explaining anything, instead it simply makes the electric
visible, so museum visitors can play with them. The motion of its pattern
of lights follows the actual motion of charges in the wires, and when the
device is connected into a real functional electrical circuit, it provides
a window on the true nature of "electricity." If all the individual
conductors in a complex schematic were replaced by a number of these
the operation of a complicated electrical device can be directly observed
and intuitively understood.
"Visual Electricity" is simply an amp-meter having a "chaselight" circuit
as a readout device.
A Chaselight is identical to a movie marquee
lightbulb border, with a pattern of on and off lights which advance along
and simulate motion. The input terminals of my device are physically
placed near the ends of a row of LEDs, and electric current passing
between the terminals is measured and used to drive some logic circuitry.
The current being measured does not drive the LEDs directly of course.
The logic circuitry lights every fourth LED, and by advancing this pattern
of LEDs, a row of glowing "electrons" can be made to flow along. The
direction and speed of chaselight action is proportional to the direction
and amperage of electric current inside the wire. To the observer this
device behaves as a wire which contains large, visible, movable electrons.
The above device is a wire with visible electrons. It also is an electric
current microscope, since it greatly amplifies the speed of electron
motion which occurs in wires. Contrary to popular belief, electric
current is a very slow flow of electric charge. At normal densities of
electric current, electrons move at speeds on the order of inches per
hour, like the minute hand on a clock. Even if individual electrons could
be seen by human eyes, their flowing motion would be invisible because
it's just too slow. Visual Electricity depicts this motion several
thousand times faster than it actually is.
The whole circuit could be made cheap and simple through use of a single
chip microcomputer having a A/D input, such as PIC16C7x. Right now the
price is very high. If the sales volume went up, I could change over to
SMT packages and automatic production; maybe get the production price down
below $10 each, so each student could have one, as opposed to a single
expensive device for one classroom as things stand now.
The next advancement is to make the LED pattern stop jumping. Electrons
in wires don't jump (they behave more like water molecules; moving along
smoothly but also jittering around with thermal/quantum vibrations.)
Also, one common misconception involves the (wrong) idea that electrons
jump from atom to atom. So I need to get rid of the jumping. Add a PWM
cross-fader algorithm, so the light pattern moves smoothly from LED to LED
A further advancement is to add a "visible voltage" function. This could
be done through use of red/green LEDs, by measuring the voltage on the
input terminals with respect to a third "ground" terminal connected to
conductive rubber legs, then driving the R/G LEDs with a pulse-width
modulated signal. If Visual Electricity as a "wire" is then connected to
a positive voltage source, the display turns red. If negative, it turns
green. If disconnected, it could either maintain an "electrostatic
charge" like a real wire and remain at its last color, or it could turn
yellow (50-50 red/green). The voltage and current on a single wire could
then be displayed simultaneously with "electrons" which change color, flow
along, or both. A square wave voltage signal would be a red/green
flashing. A sine wave signal would change smoothly: red/yellow/green and
- Bill Beaty, 6/28/95
Brief history: 1987 Brainstorm! While on a trip to Exploratorium in California, I realize that their displays with current meters could be replaced with schematics having "chaselight" LEDs, with current probes to move the LED-pattern proportional to the actual speed of electrons. 1988 I design an etch PCBs as "chaselight" current meters, and build a temporary exhibit: a motor-generator pair with green LED chaselights to indicate the electron-flow as one crank or the other is turned. I want to build a microprocessor version but don't know assembler language for the MC68705. I also want to build a version with rd/grn LEDs controlled by conductor voltage (with some sort of reference conductor, perhaps use metal magnets on the bottom and stick them to a metal board mounted on the wall.) 1989 Chaselight meters are built into two exhibits in the VandeGraaff Hall at Museum of Science (this just after I moved to Seattle.) 1990 At Dinamation Inc., I demonstrate the device to the company pres. I imagine building a hall-effect current sensor or clamp-on probe, so the LEDs will flow in the correct direction regardless of which way the physical device is oriented. 1992 I etch a long thin two-PCB version using bar-graph LED modules and rechargable batteries. TEKNOS Inc. sells a set of ten "chaselight current meters" to LLNL (or was it LANL?), delivered Jan/93. 1993 Arbor Scientific produces a less expensive version in a plastic tube using discrete LEDs and 9V battery, advertised in their '94 catalog. 1994 I learn assembler for MC68705 and microchip PIC, but *still* haven't got off my butt to build a one-chip version or a red/green version. 1995 I start a webpage; upload my schematics and PCBs so anyone can build the device. ?1996? Arbor Scientific starts a website store, so finally teachers on internet can buy my invention. 2004 I talk with D. Durlach, who uses the electric current chaselight idea in an exhibit for science musuem New York Hall of Science. 2005 Completely independantly, Kamata and Hara of Tokyo Gakugei University invent a much improved color-changing version with voltage/current sensing, based on a PIC microprocessor. See: https://iopscience.iop.org/article/10.1088/0031-9120/40/2/005/meta
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