Abstract: A microprocessor controlled automobile security system provides several features for enhanced operability. The system allows a receiving unit to learn a plurality of operating codes from a plurality of uniquely coded transmitters with which it can operate, thereby allowing each transmitting unit to be sold separately from each receiving unit. The system also allows for an operator to personally set the threshold at which a signal detected by a shock detector will result in an alarm being triggered. The system is further selectively operable in either a manual arming mode or a passive arming mode. The system also allows selective operation in either a full current sensing mode in which either a detected shock above an absolute threshold or a .DELTA. threshold, or current flow above a predetermined level, will trigger an alarm system or operation in a shock and current integration mode in which if a detected current exceeding a predetermined threshold and a shock above an absolute or .DELTA.

Abstract: The motor speed control circuit senses average back EMF as a measure of motor speed. The back EMF charges a capacitor circuit which accumulates charge and develops a voltage indicative of the motor speed. A sample and hold circuit may be used to sample the back EMF when the motor is switched off during each cycle. This voltage is compared with a reference voltage indicative of the desired motor speed. An error signal is generated by comparing the desired speed with the actual speed and this error signal is used to generate a variable duty cycle pulse train which gates the power controlling transistor on and off to control motor speed. A logic gated or SCR gated voltage boosting circuit operates in synchronism with the gating pulse train to drive the power transistor hard into saturation. This lowers the resistance of the power transistor, causing less energy dissipation as waste heat.

Abstract: A non-isolated battery charger for direct connection to an AC source provides rectified DC current to the battery being charged. A thermostat in a heat conducting relationship with the battery senses battery temperature and discontinues the charging current when the temperature of the battery rises after attaining full charge. In one form of the invention, a trickle charge path is provided to the battery to maintain its charge state after the full charge has been attained. The trickle charge path is provided by an impedance shunting the thermostat and is operative as a current path when the thermostat is in its open condition. The trickle charge path can be a resistor where the thermostat is in the DC part of the charger circuit or a capacitor where the thermostat is in the AC part of the charge circuit.

Abstract: A waveform synthesizer for generating single or poly-phase waveforms of selected wave shape and frequency for driving AC machinery including, for example, single or poly-phase induction, synchronous or other type motors or the like, includes a plurality of controllable power-switching device pairs for selectively switching power from an oppositely poled DC source to the corresponding power utilizing circuits of the driven device. The swithching device pairs are controlled to provide switched pulses of selected widths, spacings, and repetition rates to generate the desired current waveform. The power switching device pairs are selectively switched by a control circuit that includes a microprocessor controlled memory that is divided into p addressable pages with each page including s sequentially accessible memory locations containing the switching device pairs control information necessary to synthesize the desired waveform.

Abstract: The multilevel inverter includes a voltage divider which when connected across a dc source E.sub.D, provides voltage at terminals having values between +E.sub.D to -E.sub.D. A first and a second set of thyristors pairs are connected between the positive or negative terminals, respectively, and a load terminal for applying selected voltage levels to the load. Any thyristor pair in these sets may be turned-off by firing the thyristor pair at the next highest voltage level. However, the main thyristors which are connected to the +E.sub.D or -E.sub.D terminal is turned-off by a commutation circuit. This circuit includes a single capacitor maintained at zero voltage and subjected to an oscillating voltage during the commutation cycle to turn-off the conducting main thyristor. Such an inverter can easily provide a waveform having a series of pulses at one or more voltage levels thereby eliminating harmonics in the output.