Abstract: The present invention provides an HVAC fan control that includes a front fan switch, controller, rear fan switch, rear fan control circuit and a fan motor. The front fan switch and the rear fan switch electrically connect to the controller. Also, the fan motor is electrically connected to the rear fan control circuit and a front fan switch. Accordingly, the controller is responsive to inputs form the rear fan switch to operate the rear fan control circuit and select a desired fan motor speed when a logical ON condition is provided by the front fan switch.

Abstract: An electronic circuit board, together with the components, circuits, and wiring patterns thereon, is encapsulated by a single heat-shrink tubing layer, or the like for insulation from environmental factors. A method for the encapsulation is disclosed, as well as products incorporating the inventive approach.

Abstract: An adaptive knock control for a spark ignited, internal combustion engine is disclosed in which a signal indicating sensed knock induced and other bursts of engine vibrations is passed through a bandpass filter effective to tune the apparatus to a characteristic knock frequency which is variable with engine speed. The filter tuned frequency may be varied directly with engine speed to follow the characteristic knock frequency. Additionally or alternatively, it may be varied, at a particular engine speed, in a first direction away from the knock frequency avoid a strong engine noise component in the opposite direction from the knock frequency.

Abstract: An adaptive knock control for a spark ignited, internal combustion engine is disclosed in which a signal representing sensed knock induced and other bursts of engine vibrations is demodulated to generate pulses corresponding to the envelopes of such knock induced and other burst of engine vibrations. Discrimination apparatus responsive to pulses duration compares each to a discrimination reference and selectively discriminates in favor of those having a longer duration characteristic of knock induced bursts. The discrimination apparatus is responsive to engine speed to vary the discrimination reference therewith in the direction of shorter time durations with increased engine speed and longer time durations with slower engine speed. If the discrimination apparatus is a low pass filter, its corner frequency is varied directly with engine speed. If the discrimination apparatus is an ignore timer, the ignore time is varied inversely with engine speed.

Abstract: A knock control for a spark ignited, internal combustion engine including an AGC amplifier in which the amplified sensor signal is demodulated, processed and compared to a fixed reference level to generate a pulsed knock signal. An error signal is generated from the difference between the signal input to the comparator and a desired signal voltage level; and the error signal is integrated to create the AGC control signal. The integration rate is decreased during each knock indicating pulse of the pulsed knock signal output of the comparator to reduce the effect of knock on the AGC control voltage and thus stabilize the AGC control. In particular, the error signal is a current level signal; and the input to the integrator includes a series impedance with a bypassing switch controlled by the comparator output to force the input through the impedance only during knock indicating pulses.