Abstract: In an intermittent windshield wiper system in which the time between wiping cycles depends upon the degree of dryness of the windshield and upon the speed of the wiper blades on the downstroke of the wiping cycle toward the dwell position of the wiper blades, a circuit is provided to regulate the speed of the motor on the down stroke making use of the same transistor device that is used in controlling the energization of the motor to achieve intermittent operation. The motor is a three-brush motor and speed regulation is achieved by deriving signals from one or two of the brushes and applying it to the input electrode of the transistor device. The regulated speed of the motor can be manually controlled to provide a manual adjustment to the sensitivity of the system to the degree of dryness of the windshield.

Abstract: In a logic circuit, a transistor performs the function of a binary switching device and is controlled by the currents applied to the base thereof through differently weighted resistors. The resistors are connected to inputs to which signals representing different binary variables can be applied. The base of the transistor is also connected to a source of voltage through a variable resistor. By varying the value of the variable resistor, the logical function performed by the gate can be varied.

Abstract: A compensated differential amplifier connected to multiple analog ladder networks at each input which ladder networks are scaled with respect to each other and to the degree of possible compensation of the amplifier to provide a digital-to-analog converter which possesses characteristics of continuity and proportionality over the analog output range.

Abstract: The condition of a surface is sensed by cyclically moving two members having engaged surfaces relative to each other, driving the surfaces for only a portion of each cycle to set up a threshold kinetic energy level in accordance with the friction between the engaged surfaces, sensing the kinetic energy developed in one of the members due to moving the members relative to each other, comparing the developed kinetic energy with the threshold kinetic energy and controlling the cyclic movement of the members in accordance with the relationship between the kinetic energy threshold and the developed kinetic energy. The cyclic movement of the members is then used to provide a visual indication of the condition of one of the surfaces.

Abstract: Control apparatus for an electric windshield wiper motor to permit a plurality of desirable windshield wiper system features to be realized including continuous and intermittent wiping operation with variable dwell, and coordinated manual or automatic wash and wipe operation. Some of the circuits implementing the control apparatus include a Zener diode and require only a single capacitor.