Power supply monitoring and protection circuits

• 220V Mains Monitor - With this circuit you will be able to monitor the quality of the mains. There are 4 distinct sections, each supervising a parameter pertinent to the quality of the supply line. There are sections for noise, spikes, voltage and flutter.
• Circuit breaker monitors leakage current - This residual-current circuit breaker continuously monitors the supply lines for any leakage current and immediately disconnects the supply if necessary.
• Circuit breaker has programmable delay - this circuit provides overload and short-circuit protection to a 5V power-supply output
• Circuit protects against ac-line disturbances - operates by switching off the power supply upon detection of undervoltage or overvoltage conditions
• Circuit safely applies power to ICs - Supervisory circuits normally monitor a microprocessor's supply voltage, asserting reset to the IC during power-up, power-down, and brownout. In this way, the circuit ensures that the supply voltage is stable before the microprocessor boots, thus preventing code-execution errors. This circuit works so that is connect power to sensitive ICs only when they are at safe level.
• Circuit senses high-side current - The accurate, high-side, current-sense circuit does not use a dedicated, isolated supply voltage, as some other schemes do.
• Comparator detects failed telecomm supplies - detects when telecomm power supply's 48V output drops below its nominal value, uses an isolated comparator to monitor two 48V telecomm supplies (of either polarity)
• Current limiter provides latch-up signal - current-limiting circuit both signals a latch-up condition and prevents latch-up-induced overcurrent destruction of a CMOS IC or group of ICs
• Current limit protects power bus - protects a power bus from a load short within a guaranteed 2 µsec response time
• Detect Fan Failure With A Single Transistor
• Double-ended flashing voltage monitor using LM10 - can detect an over and under-voltage condition and flash LED
• Electronic fuse emulates fast- or slow-blow fuses - The electronic-fuse circuit in this article combines the properties of a current transducer and a solid-state relay to disconnect low power at preset levels. Using this circuit lets you avoid the bother of stocking and replacing fusible links.
• Fuse Monitor / Alarm - a simple way to see if a fuse has blown without removing it from its holder
• High-current trip - electronic fuse circuit will quickly break the circuit when the current exceeds about 50A
• Mains power failure alert
• Microamps monitor dual-supply batteries - low-power circuit monitors two 9V batteries in a dual-supply configuration and turns on the Battery Low LED if either battery voltage drops below its limit
• Monitor high-side current without an external supply
• Optocoupler extends high-side current sensor to 1 kV
• Overload and reverse-current circuitry protects battery and load - there are numerous circuits can protect against backward installation of batteries and other overcurrent-causing conditions
• Over Voltage Protection - describes crowbar technique that provides a useful defence for fast over voltage spikes and transients that could cause damage to more sensitive components
• Power-Supply Failure Alarm - alarms with beep when mains power feed fails
• Protection for your Electrical Appliances - very low-cost circuit to save your electrically operated appliances from the effects of sudden tripping and resumption of mains supply, this circuit switches off the mains supply to the load as soon as the power trips
• Simple Current-Limiter And Power Switch Offer Overcurrent Protection
• Single LED indicates two power states - uses a single bicolor LED to indicate both power-on and blown-fuse conditions
• The fuse monitor - a neon glow lamp indicates by remaining lit that the fuse is in order, by blinking that the fuse has blown and by remaining off that there is no power
• The main voltage monitor - main voltage monitor that is simply a lamp that glows when the main voltage is present, designed for 230V AC, can be adapted to 110V AC operation
• Two-lead solid-state breaker resets itself - simple dc circuit breaker can protect a power supply from the ever-present screwdriver or even isolate a satellite's dual power system from a short circuit in one subsystem