The problem of low-noise hand-held cameras was remaining still relevant in the USSR, in connection with which the MKBK (Moscow Cine Equipment Design Bureau) continued to work in this area. So at the end of the 70’s a new 3KSR model camera (chief designer L. Z. Kaplan) was developed, which was equipped with a mirror shutter with opening angle of 180°, a synchronous electric drive with quartz (crystal) stabilization, built-in exposure meter, with a 6kg (about 13.2lbs) weight, and had a noise level of about 42dB. This unit was manufactured in small batches by the MOSKINAP (Moscow Cine Equipment Factory) during 1980-1983.
An electric motor unit 1 located on the shaft of which a toothed pulley 2 is used for driving mechanism. The mechanism of the camera is covered by one toothed belt 3, which provides a constant tension roller 4. Through the rotation of a toothed pulley 5 is transmitted to the claw mechanism shaft 6, on which there is a screw gear 21 for transmitting the rotation through the helical gear shaft 20 of the shutter 7.
The unit linked kinematically to the magazine mechanism by means of a cylindrical toothed wheels 8, located on the shaft of the toothed pulley 9.
Magazine mechanism is set in motion when the clutch spur gear 8 with the spur gear 10 located on the shaft retarding sprocket 11. The entire magazine mechanism covered by a toothed belt 12, which provides constant tension to the tension rollers 14. From sprocket 13, rotation is transmitted through a gear pulley shaft 15 pulling the sprocket 16 and 17 through the pulley – winder shaft 18. Supply roll 19 is inside the magazine location and the braking device.
Photoelectric sensors mounted at one end of the motor shaft and the rotational speed of the motor mechanism stops in the viewing position. The speed sensor is mounted on the motor drive shaft 22 with a diameter of 40 at 100 mm radial slits intersecting the path of the rays by the rotation of the photo coupler formed by the light source 24 and a photo-detector 23. The photo-detector signal, worked out by a finite number of electrical pulses per unit time, is a feedback signal for the automatic control system of the motor speed. To stop the mechanism in the viewing position, adjustable dimension on the motor shaft is set to the shaft angle with the shutter angle of 60°, crossing the path of the rays while rotating the second optic-coupler, the signal from the photo-detector 25 which defines the operation of the motor control after the pushing the trigger button.