Safely swap SCSI disk drives:  09/30/99 EDN-Design Ideas / (added 11/05)

Safety Deviceuses GMR sensor:  07/10/03 EDN Design Ideas  /  (added 1/05)  This Design Idea presents a differential safety device to prevent risks arising from current leakages in household applications. The proposed circuit uses a new method for differential current sensing (Figure 1). The method entails the use of Helmholtz coils and a magnetic sensor based on the GMR (giant-magnetoresistive) effect....

Short circuit protected Power Supply from PC 12V supply:  (Electronic circuit added 4/05)

Short-Circuit Protection for Boost Regulators:  DN154 -  Design Notes (Linear Technology) (added 1/06)

Shunt Regulator Provides overVoltage Protection:  01/15/98 EDN-Design Ideas / (Circuit / schematic design added 6/06) The circuit in Figure 1 uses a typical technique for varying the output voltage of a power supply via a programmable control voltage. Although the topology and schematic details of the power supply are not critical, the protection technique is novel.

Simple Circuit Protects Systems from Overheating:  App Note 1126: Maxim IC  (Circuit / schematic design added 6/06)

Simple circuit safely deep discharges NiCd battery:  04/29/99 EDN-Design Ideas / (added 2/06)  Nickel-cadmium (NiCd) batteries can possess an undesirable memory effect due to partial discharges. The remedy is a complete discharge before charging again. Figure 1a shows a simple circuit that performs this feat. Although relatively straightforward in concept, the circuit has three redeeming features: It receives its power from the battery undergoing the discharge; after the battery is fully discharged, the current drain is only approximately 4 µA, which is usually...

Simple Electronic Circuit Breaker:  This circuit uses the on-resistance of the MOSFET as the current sensor. Reset it by removing the input power or the load. The circuit draws no current unless tripped.  Designed by Andrew R. Morris  (added 09/05)

Single Transistor provides short circuit protection:  10/16/03 EDN Design Ideas  /  (added 1/05)  In certain dc/dc-converter applications, on-chip, cycle-by-cycle current limit may be insufficient protection to prevent a failure during a short circuit. A nonsynchronous boost converter provides a direct path from the input to the short circuit through the inductor and the catch diode. Regardless of current-limit protection in the IC, when a short circuit exists in the load, extremely high cu......

Slic protection for both classical and New networks:  AN2053  (Circuit / schematic design added 6/06)

Smart switch cuts transformer turn on Current :  04/23/98 EDN-Design Ideas / (added 11/05) [Note:  File contains multiple circuits - scroll to find this circuit.]  Transformer-core saturation can cause inexplicable fuse blowing, system crashes, or premature switch and relay failure. When a core saturates, it loses its inductive characteristics; primary winding current can then reach extremely high values for several ac cycles. Turning on a transformer may seem fundamental, but in some power-supply designs and control applications, it can be a game of Russian roulette. Because transformers remain polarized when turned off, saturation occurrence is a function of the polarity and phase angle of the ac cycle when you switch the circuit on and off. The smart-switch circuit in Figure 1 eliminates saturation, improves relay reliability, and provides a tool for determining transformer and relay performance....

Spark gaps Provide ESD Protection:  09/01/97 EDN-Design Ideas / (Electronic Circuit diagram added 03/03)  

Speaker Protector:  (added 6/03)

Switcher improves overVoltage protection circuit:  06/10/04 EDN Design Ideas  /  (added 1/05)  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 one to provide a robust overvoltage-protection circuit.

Thermal Protection in Low-Cost Systems, Part 1:  App Note 961: Maxim IC  (Circuit / schematic design added 6/06)

Thermal Switches provide circuit disconnect:  09/04/03 EDN Design Ideas  /  (added 1/05)  A single temperature sensor can provide an interrupt to a microcontroller when the measured temperature goes out of range. You need multiple temperature sensors when you have to monitor more than one hot spot. A microcontroller implements the proper protective action when one of the temperature monitors detects an overtemperature condition....

Transient protection solutions : transil and #153 diode versus varistor:  AN1826  (Circuit / schematic design added 6/06)

Transistors offer thermal protection for Controller:  07/19/01 EDN - Design Ideas / (Electronic circuit added 10/03)  When a switch-mode power-supply controller, such as On Semiconductor's NCP1200, operates at a high ambient temperature, you should protect the entire power supply against lethal thermal runaway. The NCP1200 operates directly from the power mains without an auxiliary winding; therefore, the die in the IC dissipates power (Figure 1)..

TTL Power Supply with Crowbar Protection:  The regulator IC is the familiar fixed voltage type such as LM7805. The 7805 is a three-pin regulator which requires a minimum voltage input of 7.5V to sustain stabilization, which an absolute maximum input voltage of 35V. The maximum load current is 1A and the regulation against input changes is typically 3-7mV for a variation of input between 7.1V and 25V. The regulation against load changes is of the order of 10mV for a change between 5mV and 1.5A load current. The noise voltage in the band from 10Hz to 100KHz is 40-50uV, and the ripple rejection is around 70db. Maximum junction temperature is 215 degrees C, and the thermal resistance from junction to case is 5 degrees C/W. This stabilizer is used extensively for power supplies in digital equipments.... (Circuit / schematic design added 6/06)

Two Buttons provide safe start:  07/06/00 EDN-Design Ideas / (added 8/03) - This circuit provides a safety interlock that checks the actuation of two pushbuttons before enabling a relay. When you push both buttons, the circuit actuates the relay. At that point, you can release one of the switches without the relays switching off. The circuit was intended to lock out the engine of an underwater propulsion unit.

Undershoot Protection When using Bus Switches:  Pericom Semiconductor Application Note # 030 (added 2/05)

Understanding the Power Supply Requirements of PCI Bus Standard-How to Protect the Digital Components:  National Semiconductor - Application Note   (added 2/06)

Universal Pots Interface Lightning Protection:  Melexis Application Note  (Circuit / schematic design added 6/06)

Voltage Monitor Prevents Deep Discharge of Battery:  05/07/98 EDN Design Ideas / (Circuit / schematic design added 6/06)   contains multiple circuits - scroll to find this circuit

Watchdog Circuit Protects Against Loss of Battery Charger's Control Signals:  07/21/05 EDN Design Ideas  / (Circuit / schematic design added 6/06)  Hardware circuit keeps software-based charging within limits.

What is a Thyristor Surge Protector Device:  MicroNote 105 from Microsem - Reviews the basics of an avalanche voltage triggered thyristor designed for transient voltage protection, used largely for telecom signal lines - (Circuit / schematic design added 6/06)