Abstract: There is disclosed a battery-operated motor control circuit. An adjustable voltage reference (18, 26, 28) is coupled to the battery (10), with the output of the adjustable voltage reference being coupled to the positive input of an operational amplifier (34). The negative input of the operational amplifier (34) is coupled to ratio control means (60) for setting the gain of the operational amplifier (34) and thus setting the motor (54) to a selected speed. A transistor-pair amplifier (38, 40) is coupled to the output of the operational amplifier (34), with a negative feedback line (50) being coupled from the output of the transistor amplifier to the negative input of the operational amplifier. The motor is also coupled to the output of the transistor amplifier.

Abstract: Apparatus for applying a radiant beam against an opaque diaphragm (18) to melt an aperture in the diaphragm (18). Bracket means (12) are provided for positioning the diaphragm (18) at a predetermined position, along with a source of the radiant beam (20) and electric circuit means (21) for activating the source (20). Photocell means (52) may be positioned whereby a properly positioned diaphragm (18) initially shades the photocell (52) from the beam, and the beam strikes the photocell (52) when the aperture is formed. Means are provided to shut off the radiant beam responsive to the beam striking the photocell (52). The photocell (52) may be positioned in a pivotable switch arm (46), and the radiant beam source (20) may be a special filament-type light bulb (20) with a focusing reflector (24).