Ethan wrote:
> How does a resistive sheet computer work?
I wrote:
> Resistive sheets belong to a category of analog
> computing called network analyzers.
Oops, I need to correct this.
Resistive sheets belong to a category of analog
computing called passive element computers in which
network analyzers are probably the biggest and most
well known examples. But it also includes
* conductive sheets
* electrolytic tanks - create 3 dimensional simulations
* resistor networks
* pin and rod systems
* resistor and capacitor network
Passive element computers normally models a
physical system using only passive R-L-C components,
and solve equations in which dimensions in space
are the independent variables, rather than time.
Applications for passive element computers include
things like the simulation of
* reception patterns of a receiving antenna
* temperture, and pressure flow in a nozzle
* diffusion of material at a transistor junction
Here is an example:
You solder together a large two dimensional matrix
of resistors (all the same value). At each node where
the resistors are soldered together you solder a capacitor
connected to ground.
You then apply a voltage to one corner of this
resistor and capacitor network. As the current flows
through the network it begins to charge the capacitors.
You now have a computer that simulates the heat flow
across a metal plate the size of your matrix, both
over distance and over time. Without the capacitors
you are simulating only over distance.
A resistive sheet is a resistor matrix with a very
fine mesh. The finer the mesh, the better the simulation.
"Rubber-sheet computers have been used extensively
to study the trajectories of electrons and gas ions
in vacuum and gas tubes"
-Doug
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Doug Coward
_at_ home in Poulsbo, WA
Analog Computer Online Museum and History Center
http://dcoward.best.vwh.net/analog
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Received on Fri May 02 2003 - 17:12:00 BST