Abstract: An interface device 3 is used to couple a first 101 and second 201 bi-directional signal path, such as 12C. The first bi-directional signal path 101 floats at a logic high level. Stations 110 coupled to the first signal path 101 are capable of generating a logic low level on the first signal path 101. To avoid that the system gets latched in a low state, a medium logic level is used on the first signal path 101. The interface device 3 generates the medium logic level on the first bi-directional signal path 101 in response to a low logic level on the second signal path 201. The interface device 3 generates on the second signal path 201 a low logic level in response to a low logic level on the first signal path and, otherwise, generates a high logic level. The stations 110 on the first signal path 101 detect the medium logic level and the low logic level as LOW and the high logic level as HIGH.

Abstract: A bridged driving amplifier for driving a capacitive load comprises a first and a second output terminal, and a first and a second supply rail. A first driving section is coupled between the first supply rail and the first output terminal. A second driving section is coupled between the second output terminal and the second supply rail. A third driving section is coupled between the first supply rail and the second output terminal. A fourth driving section is coupled between the first output terminal and the second supply rail. The bridged amplifier is AC-driven such that the first and the second section, when driven, cause an output voltage across the capacitive load of a given polarity, and that the third and the fourth section, when driven, cause an output voltage across the capacitive load of a polarity opposite to the given polarity.

Abstract: A trigger control circuit of the kind wherein a load is supplied via a triac with current from an AC voltage supply source under the control of a triac control means in combination with a sensing element. In previous circuits the sensing element is energized by a current from a DC source which is derived by rectification and smoothing of the alternating current of an alternating voltage supply source. These circuits have limitations in integrated circuitry. The sensing element herein is energized by an alternating current to produce a sensed alternating current. The triac control means includes an integration element for producing a control signal which represents of the integral of the difference between a value corresponding to the magnitude of the sensed alternating current and a reference value. The triggering or otherwise of the triac is determined by a latch actuated in response to the magnitude of the control signal relative to one or more threshold levels.

Abstract: A circuit for detecting the crossings by an applied alternating voltage of two separate voltage threshold levels above and below a fixed reference voltage level. The circuit includes the series combination of two resistances (1 and 2) in an electrical path between the applied alternating voltage and a dc reference voltage. Two voltage comparators each having two logic output states compare the voltage at the junction (P) of the two resistances with the reference voltage so that the logic output state of the comparators at any instant is determined by the voltage at the junction relative to the reference voltage. A logic gate combines the logic output states of the comparators to produce a pulse spanning each instant of cross-over by the alternating voltage of the reference voltage. The pulse has a leading edge and a trailing edge which respectively correspond with the instants of crossing by the alternating voltage of the two separate threshold levels.