Rapid braking circuit for small motor - short circuits machine for preset time and has two semiconductors of which second operates under control of timer

摘要

The motor (M) is under the influence of a controller (2) which either opens or closes the circuit through the motor by means of a semiconductor (Tr1). When in the off state the controller (2) brings into conduction a second semiconductor (Tr4) which short circuits the motor and thereby enhances its retardation. The second semiconductor (Tr4) is additionally controlled by a timing circuit comprising a resistor, capasitor, diode, and an amplifying transistor (R1,C1,D1,Tr3) which serves to maintain the short circuit for a predetermined time or until the controller switches the motor on again. The controller holds the timing circuit in the charged state but not conducting when the motor main circuit is closed. The connection eliminates the possibility of the braking circuit being switched on by a spurious signal.