The Model 140 Digital Power Control controls the electrolyte flow, the polishing voltage and current, the light source and photodetector shutoff circuit, and both visual and audible alarms. Digital displays allow precise setting and monitoring of the electropolishing voltage and current levels. 

The photodetector circuitry detects the first sign of light penetration through the specimen and activates both audible and visual alarms, independent of the position of the pump and polish switches. 

A switch activates current flow and controls the light source. The amount of light required to activate the photodetector shutoff can be adjusted to control the perforation size in the specimen. 

LEDs indicate which mode of operation is active. 

Pump Auto mode. Stops the electrolyte flow when light penetrates the specimen. 

Pump Continuous mode. Pump remains activated after light has penetrated the specimen and the photocell circuitry has activated the alarms. This feature allows polishing to be extended past the point of a small perforation in the specimen. 

Polish Auto mode. Stops the polishing current when light penetrates the specimen. 

Polish Continuous mode. The voltage remains activated after light has penetrated the specimen, allowing for continuous polishing while the switch is on. 

At any time during an alarm condition, the audible alarm can be silenced. The alarm indication light remains illuminated.