Abstract: A speed governing system utilizing a magnetic pickup for sensing speed with a frequency-to-voltage transducer of the type in which each input signal initiates a counting cycle by a digital counter receiving relatively high, constant frequency input pulses to measure off a predetermined time interval, and characterized in that the output signal from the counter itself forms a variable duty cycle squarewave signal whose dc. or average value varies according to changes in the input signal frequency. The counter output signal also controls termination of each counting cycle. The transducer may include means for converting the transducer output signal to a failsafe level in the event that sensed speed and the input signal frequency become so great that there is an erroneous attempt for the system to stabilize at twice the set point speed.

Abstract: In electronic flash apparatus having a flash trigger switch and a flash termination switch, protection against damage from large negative gate voltages is provided. The gate of the flash trigger switch is connected to the cathode of the flash termination switch, and the gate of the flash termination switch is connected to the cathode of the flash trigger switch.

Abstract: In electronic flash apparatus having a flash trigger switch and a flash termination switch, an RC network is provided to apply current to the control electrode of the flash termination switch when the flash trigger switch is in a conductive state.