Transmutascope: Electrical Systems
The Transmutascope's electrical block diagram is shown at left.   There are 2 main systems: motor control and the LED pulsing. 

In order to get the very bright flashes needed, the LEDs are pulsed at high currents: 3 amps per LED, times 8. (LED Pulsing described in more detail here)  The pulses are brief, and only on only a small percentage of time, therefore installing a power supply capable of supplying the full 24A peak load would be wasteful.   Instead, a large power buffering capacitor is used to supply this peak load.  The 1 ohm power resistor (left of cap) prevents the power supply from "dropping out" during the capacitor's recharge. It also effectively isolates the 2 circuit boards from major powerline noise caused by the LED pulsing.

The 1 watt white LEDs each have a 1 ohm resistor (not strictly necessary) to even out load sharing.  

The key element of the system is the LED Pulse Controller circuit (diagram below).  It handles the important task of making sure the LEDs don't stay on too long.  Keep in mind that unlike a typical LED circuit, there is virtually no current limiting resistance here. If the LEDs were commanded to stay on a bit too long, they would all be destroyed.  The LEDs are low-side-switched on for about 800uS each time a trigger occurs.  The trigger is provided by an optical slot sensor.

Motor control is handled by a CPM5 unit, reading a speed control pot mounted to the outside of the machine.
LED Pulse Controller circuit diagram.  Click for larger version in new window.
Transmutascope with media disk removed.

Note: shown gearmotor system was changed due to excessive acoustic noise.
Slot Sensor -
triggers flash
when pin
passes through
sensor wires carried in shielded cable to prevent false triggering
Urethane Belt
A close up horizontal view of the OPB817Z sensor (Digikey).  This type of sensor has a light transmitter on one leg, and a reciever on the other.  There are many shapes and sizes of such slotted optical switches" available.

The media disk rotates above and has pins aligned with each object.  When an object is aligned, its pin passes through the sensor, blocking light.  This is detectable by the LED Pulse Controller circuit.  The position of the pin when triggering occurs is accurately repeatabe.
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works of  Carl C Pisaturo