Stamp interface to Allegro Motor Driver

This is a very successful project David has underway that uses a UDN2916B motor driver IC out of a printer to control a bipolar stepper motor with a Stamp micro-controller. It demonstrates very accurate discrete control of the stepper motor via parametric changes in variables in the code. Our plan is to create a board layout and use an outside service to produce a printed circuit board. The next step is to scale the architecture with a two-level multi-Stamp model to control multiple boards.

Data from Air Cannon Velocity Timing Measurement

This is a very interesting graph of data we collected using the same cork as the pressure in the feed tank (bottom trace) declined with each firing. The time (count) pattern shows erratic performance and slower speeds at very high pressures followed by a dramatic increase in cork velocity at about 40psi. A fairly stable and smooth curve from 40psi to 20psi where the speed then falls off to a new regime at slower speeds. For perspective, 146 f/s = 100 mph. Double clicking on the graph will bring up a larger and more readable view.

Timer Update & Initial Success !

Completed assembly with with IR LED and photo transistors (two additional transistors tied with the photo transistors in a Darlington configuration drive negative pulses are on breadboard to the right) harvested from small circuit board position detectors (Omron) and mounted 24" apart in the PVC barrel seen at bottom of photo. Wiring between barrel and circuit board uses a standard cat5 connector that can be used for extension) Running the clock at 93Hz measured (end counts on display of 4 and 5) and 8106Hz calculated (end counts of 377, 433, etc), we fired a cork under human air pressure and found consistent results measuring speeds between 37 and 46 feet/second. We'll hook up the rest of the air cannon and air tank after lunch! Hard to see but the blue decoupling caps are from my days working at Raytheon....some time ago...

Timer Circuit Prototype

Early work on a timer circuit for measuring the velocity of a cork or tennis ball in our air cannons. A 74C926N counter is driven by a 555 timer running at a known (93Hz) frequency. A second 555 timer in monostable mode is used to start (trigger) and stop (reset) the clock generator (first 555) with negative pulses from photo transistor/IR LED gates located on the barrel.

Alta-Yellow Trail

Note the very small figure at the bottom right standing on the mound of snow without ski tracks......the parents took an easier route down....