Comparator for over-voltages

Description: To maintain an alarm condition when an overvoltage transient disappears, an SCR should be added to the comparator circuits. For SCR operation, the voltages to the comparator inputs are inverted. The triple-voltage monitoring circuit detects transient power-supply over-voltages. If excessive voltage momentarily appears at the 5V, 12V, and -12V inputs, the LED for that circuit lights up, and the beeper sounds for as long as the condition persists.

The described circuit employs a silicon-controlled rectifier (SCR) within a comparator configuration to ensure that an alarm condition is sustained even after the overvoltage transient has ceased. The SCR is a semiconductor device that can switch from a non-conductive to a conductive state when a gate signal is applied, thus maintaining the alarm state until the circuit is reset.

In this implementation, the comparator circuit continuously monitors the voltage levels at three critical power supply inputs: +5V, +12V, and -12V. These voltages are fed into the comparator, which compares them against predetermined threshold levels. When a voltage level exceeds the defined threshold, the comparator output transitions, triggering the SCR. The inversion of the input voltages to the comparator is essential for proper SCR operation, allowing it to latch and maintain the alarm condition.

The visual indicator for the alarm condition is an LED, which illuminates to provide a clear visual cue when an overvoltage condition is detected. Additionally, an audible alarm in the form of a beeper is activated simultaneously, alerting personnel to the potential hazard. The beeper remains active for the duration of the overvoltage condition, ensuring that the alarm is noticeable.

This circuit configuration not only enhances safety by providing both visual and audible warnings but also ensures that transient overvoltage conditions do not go unnoticed, thereby protecting sensitive electronic components from damage. The use of an SCR in this application adds robustness to the circuit, allowing it to handle rapid fluctuations in voltage without immediate reset, thus maintaining awareness of the fault condition until manual intervention is possible. To maintain an alarm condition when an overvoltage transient disappears, add an SCR to the comparator circuits. For SCR operation, voltages to the comparator inputs are inverted. (B) The triple-voltage monitoring circuit detects transient power-supply over-voltages. If excessive voltage momentarily appears at the 5, 12 and -12 V inputs, the LED for that circuit lights and the beeper sounds for as long as the