Power supply monitoring and protection circuits ( 28 ) :

• 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 �sec response time    Rate this link
• Detect Fan Failure With A Single Transistor   
• 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.
• Electronic Fuse for Power Supply - This circuit offers effective protection against overcurrent in power supply with output voltage through to 45V DC and output current form 0.1A to 5A.   
• 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   
• 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   
• Precision circuit closely monitors -48V bus - Ever-greater complexity in communications systems has spurred a need for power-supply management. POTS (plain-old telephone systems) obtain power from -48V supplies backed by arrays of batteries in central offices and distributed throughout copper lines. This article shows how to monitor the voltage on those -48V lines.   
• 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   
• 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   
• Switcher improves overvoltage-protection circuit - Overvoltage-protection circuits often protect electronic devices from power-supply transients, such as a rise from plugging in batteries or an external power adapter. Although these devices traditionally find use as hysteretic switching controllers, you can reconfigure the LM3485 to provide a robust overvoltage-protection circuit. You can program the IC to trip off at any level from 4.5 to 35V. The LM3485 also has an adjustable overcurrent-protection feature. In the sample circuit, when the current exceeds 1.1A, the LM3485 turns off the FET. After 9 �sec, the LM3485 turns back on the FET and begins sensing the current again through the FET's on-resistance.   

Soft starting circuits

• Series Lamp Limiter - connect a 100W lamp bulb in series with the supply to the equipment being repaired to avoid very nadty high short circuit current is something goes seriously wrong, useful for power supply testing and repairing   
• Soft-Start Circuit For Power Amps - This circuit reduces the current spike large transformers take when switched on.   
• Soft Power On Tester for Amplifiers - The worst thing that can happen is that when you turn an electronics device you are fixing on, it immediately pops a fuse - or worse yet a valuable part you've just installed! If you don't have a variac with a current meter so that you can make power on gradual, the next best thing is this widget. It can be whipped up from parts in your local home supplies store.   
• Time-delay relay reduces inrush current - A transformer switching onto a line can sometimes cause a circuit breaker to trip or a fuse to blow. This phenomenon occurs even if the transformer presents no load, such as when the secondary is open. The problem arises because of the heavy magnetizing inrush current in the transformer. This design solves the problem in one way.   

 back to : Links >> Electronic Circuits >> Power Supply Circuits