Abstract: A sewing machine with spooling equipment. For a spooling operation, an armshaft of the sewing machine can be disconnected from a motor drive of the machine. Through a pulse generator for delivering pulses, the armshaft is coupled to a circuit for controlling the speed of the sewing motor. The circuit comprises an operational amplifier designed with a feedback network. To permit an automatic switching of the operational amplifier to regulation or control sewing and spooling, the feedback network of the operational amplifier comprises two resistance members connected in parallel, of which one can be disconnected by a switch which is controlled by the pulse generator. To simplify the switching, the switch is designed as an analog switch whose control line is connected to the output of a control circuit having one end connected to a starter resistor to which the operational amplifier is responsive, and its other input connected to the pulse generator.

Abstract: In a sewing machine with a universal motor, a speed control for the motor, a lamp, and a plug connection on the sewing machine housing for connecting the power supply and speed control lines to the motor and to the lamp, for equivalent replacement of the normal impedance starter by one with integrated phase angle control, a phase angle control is provided as a speed controller which comprises a rectifier bridge consisting of diodes for current supply to the phase angle control and to the lamp, as well as a rectifier bridge with semiconductor devices controlled by the phase angle control, for the control of the motor.

Abstract: A monitoring device for monitoring a low thread supply in a sewing machine comprises a light emitter and light receiver positioned on opposite ends of a rotary hook in the sewing machine. The sewing machine is equipped with the rotary hook, a bobbin case, a bobbin in the bobbin case for carrying the thread and a drive shaft for rotating the rotary hook or which rotates as a function of rotation of the rotary hook. A pulse transmitter is connected to the drive shaft which supplies pulses to a control circuit connected to the light emitter. The control circuit, responsive to the pulses, activates the light emitter only during intervals at which apertures in the rotary hook, the case and the bobbin are aligned. Light passing through the aligned apertures indicates whether there is a low supply of thread on the bobbin.

Abstract: A pulse generator of variable-speed drives, particularly sewing machine drives having a main rotatable shaft and a housing comprising a casing defining an inner space connected to the sewing machine housing, a generator shaft rotatable and synchronous with the main shaft and mounted for rotation in the casing, a pulse disc with light-dark zones connected to the shaft and rotatable within the inner space of the casing, a light transmitting module and a light receiving module connected to the casing, the casing including bearing surfaces on either side of the disc bearing against and bearing surfaces of the shaft for supporting the pulse disc for rotation. Bearing surfaces provide a seal against stray light and dust and the like and also accurately center and support the pulse disc.

Abstract: A speed control device for the motor of a home sewing machine, comprising, a comparator having one input connected to a reference voltage, an output connected to the motor and another input, a first control circuit with a variable resistor connected to the other input of the comparator and a second control circuit with a low motor speed constant resistor and a switch connected to the same other input of the comparator.