Automobile burglar alarm with battery voltage sensing means

摘要

An automobile burglar alarm including a battery voltage level sensor to be connected to the positive terminal of the automobile battery for providing an output signal level indicating the battery voltage level and responsive to reduction in the automobile battery voltage when an automobile dome light or trunk light supplied by the battery is turned on to provide a changed output signal level which persists for a predetermined time period, indicative of the reduced battery voltage level, a normally non-conducting transistor connected in circuit with the automobile headlight and horn relays to a supply voltage source to energize the relays when the transistor conducts, a timer circuit connected to the transistor to supply a timed output signal for causing the transistor to conduct for a predetermined short conduction interval, and an operational amplifier coupled to the sensor and the timer circuit for supplying an amplified signal adequate to cause the timer circuit to produce the timed output signal.