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 Safety / Protection Circuits
Safety / Protection:  # - G        H - Q        R - Z


Last Updated: December 31, 2017 06:39 AM
Circuits Designed by Dave Johnson, P.E. :

Night Light from White LED -  As many of you know, I have a pet peeve with poorly made LED night lights.  Often, the light from the LED quickly fades, so within months, the light is useless.  I have posted several versions of modified night lights using higher quality components. . . Circuit by David Johnson P.E.-November, 2008

One-Watt White LED Night Light -  As many of you know, I have a pet peeve with poorly made LED night lights.  Often, the light from the LED quickly fades, so within months, the light is useless.  I have posted several versions of modified night lights using higher quality components.  This circuit is yet another version, which produces much more light than those other designs. . . . Hobby Circuit designed by David A. Johnson P.E.-November, 2008

Power Line Alarm -  This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac.. . . Circuit by Dave Johnson P.E.-July, 2006

Protects from Battery Polarity Reversal -  This simple circuit can protect a sensitive electronic circuit from an accidental connection of a battery with a reversed polarity.  The N-channel FET connects the electronic device to the battery only when the polarity is correct.  The circuit shown was . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2002

 

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747




Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

New 8051SBC -  Brown-out protection, WDT, 20x4 LCD BUS interface.  Simple scope using Nokia 3310 LCD __ Designed by Wichit Sirichote

Night Light from White LED -  As many of you know, I have a pet peeve with poorly made LED night lights.  Often, the light from the LED quickly fades, so within months, the light is useless.  I have posted several versions of modified night lights using higher quality components. . . Circuit by David Johnson P.E.-November, 2008

Night-Light Uses a Photoresistor to Detect Dusk -  12/15/11 - Design ideas - You can adjust this battery-powered circuit for different levels. __ Circuit Design by Chau Tran, Analog Devices, Malden, MA

One Transistor Provides Short-Circuit Protection -  10/16/03  EDN Design Ideas:  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 provide as a direct path from the input to th __ Circuit Design by Keith Szolusha, Linear Technology Corp, Milpitas, CA

One-Watt White LED Night Light -  As many of you know, I have a pet peeve with poorly made LED night lights.  Often, the light from the LED quickly fades, so within months, the light is useless.  I have posted several versions of modified night lights using higher quality components.  This circuit is yet another version, which produces much more light than those other designs. . . . Hobby Circuit designed by David A. Johnson P.E.-November, 2008

Open-collector output provides fail-safe operation -  4-Sep-03 EDN Design Ideas:  it is common practice to use digital open-collector outputs for control units in industrial applications.  Using these outputs, you can switch loads, such as relays, lamps, solenoids, and heaters.  One possible problem inherent to this type of output stage is a short circuit from the output to the supply voltage (often, 24V] __ Circuit Design by Susanne Nell, Breitenfurt, Austria

Over / Under-Voltage Protection Of Electrical Appliances -  This circuit protects refrigerators as well as other appliances from over and under-voltage.  Operational amplifier IC LM324 (IC 2) is used here as a comparator.  IC LM324 consists of four operational amplifiers, ...__ Electronics Projects for You

Over Voltage Protection -  Safety devices like fuses provide protection against excess current, but do nothing for transients and short duration spikes of high voltahe on the power supply lines.  This circuit uses the "crowbar" method and provides fast protection against transient voltage spikes __ Designed by Andy Collison

Overcurrent & Undervoltage Battery Fault Protection -  The LT6109 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and two comparators.  Two versions of the LT6109 are available.  The LT6109-1 has the comparators connected in opposing polarity and the LT6109-2 has the comparators connected in the same __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Overcurrent Battery Fault Protection -  The LT6108 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and a comparator.  Two versions of the LT6108 are available.  The LT6108-1 has a latching comparator and the LT6108-2 has a non-latching comparator.  in addition, the current sense amplifier __ Linear Technology/Analog Devices App Note, Sep 7th 2011

Overload & Reverse Currentry Protects Battery & Load -  03/01/96 EDN Design Ideas:  Battery-operated equipment is prone to the consequences of backward-installed batteries, accidental short circuits, and other careless use.  The effects of a reversed battery are critical.  Unfortunately, it's difficult to guard against a reversed battery.  To make __ Circuit Design by Dana Davis, Maxim Integrated Products

OverVoltage Protection for LM317 -  it is a voltage regulator that allows a 6v portable supply to be derived from the 12v car battery.  You can add a 6.2V zener diode and a LED to warn you when the input supply is overvoltage.  if you could find a relay that would operate from 6.2v right up to 12v that you could connect in such a way that if over voltage occurred,  __ Designed by submitted Adam

Overvoltage Regulator with 250V Surge Protection -  The LT4363 surge stopper protects loads from high voltage transients.  it regulates the output during an overvoltage event, such as load dump in vehicles, by controlling the gate of an external N-channel MOSFET.  The output is limited to a safe value allowing the loads to continue functioning.  The LT4363 also monitors the voltage__ Linear Technology/Analog Devices App Note, Jan 16th 2012

Overvoltage Regulator with Low Battery Detection & Output Keep Alive During Shutdown -  The LT4356 surge stopper protects loads from high voltage transients.  it regulates the output during an overvoltage event, such as load dump in automobiles, by controlling the gate of an external N-channel MOSFET.  The output is limited to a safe value thereby allowing the loads to continue functioning.  The LT4356 also monitors__ Linear Technology/Analog Devices App Note, Apr 26th 2010

PIC Speaker Protection -  This doesn't replace P33, but it is possibly the ultimate speaker protection.   __ Designed by Rod Elliott  ESP

Polarity Protector Outperforms Schottky Diodes -  02/06/03 EDN Design Ideas:  Oscillating output improves system security - The polarity-protection circuit in Figure 1 is a high-performance alternative to the usual series diode (often Schottky].  The circuit incurs a much lower voltage drop than even the best Schottky diode.  The circuit uses MOSFET devices because of their low on-resistance.  For the transistors in this design, the combined on-resistance is 0 __ Circuit Design by Mike Hovenga, BAE Systems, Austin, TX

Power Line Alarm -  This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac.. . . Circuit by Dave Johnson P.E.-July, 2006

Power Supply Transient Protection for MNA & VNA Amplifiers -  AN-60-027 Application Note__ MiniCircuits.com

Power-line outage flashes red alert -  06/13/02 EDN Design Ideas:  This design idea expands on a circuit in a previous one to configure a power-outage detector with a flashing alarm (Figure 1, Reference 1].  The circuit plugs into a mains outlet and uses trickle-charged nickel-cadmium batteries.  The green-LED monitors the presence of line voltage.  The BZV55-C4V3 zener diode, D1 protects the batteries against overvoltage __ Circuit Design by Vasiliy Borodai, Zaporozhje, Ukraine

Power-Supply Decoupler Protects Your UUT -  05/10/12 EDN Design Ideas:  Detect and shutdown reverse polarity or overvoltage before damage occurs.  You can install the bench-top accessory in Figure 1 between a variable-voltage bench power supply and a breadboard or UUT (unit under test) to protect against accidental overvoltage and reverse polarity.  it draws its power from the supply and pulses a 5V, two-coil latching relay to interrupt power to the load under abnormal conditions. __ Circuit Design by Raju Baddi, Tata Institute of Fundamental Research, Pune, India

Power-Supply Failure Alarm -  Most of the power-supply failure indicator circuits need a separate power-supply for themselves.  But the alarm circuit presented here needs no additional supply source. __ Designed by M.K. CHANDRA MOULEESWARN

Power-supply interrupter fights ESD-Induced Device latch-up -  21-Jul-05 EDN Design Ideas:  Optoisolator-based circuit protects digital components from ESD __ Circuit Design by Emerson Segura, Lifescale Global Diagnostics Inc, Toronto, ON, Canada

Prevent Deep Discharge of Battery -  09/26/96 EDN Design Ideas:  NOTE:    Page includes several designs, scroll to find this one.  mCs such as the 8051 and 8096 and UARTs such as the 82510 provide hardware support for a multiprocessor asynchronous serial-communication protocol (MicroLan].  This featu __ Circuit Design by Rolando Herrero, Instituto Tecnologico de Buenos Aires, Argentina

Prevention & Control of Electrostatic Discharge ESD -  AN-40-005 App Note__ MiniCircuits.com

Protect Against AC-Line Disturbances -  07/02/98 EDN Design Ideas:  NOTE:    FILE
has several circuits, please scroll to find this one.  The circuit in Figure 1 protects the ac line against disturbances.  it operates by switching off the power supply upon detection of undervoltage or overvoltage conditions.  The circuit thus protects refrigerators, washing machines, air conditioners, and other appliances from permanent damage that could accrue from working outside their specified power requirements.  The problem assumes particular importance in underdeveloped countries or regions where the ac-supply network is incorrectly configured, and the voltage frequently drops to levels low enough to damage coils and motors.  When the ac-line voltage returns to its nominal level, the circuit automatically resets a switch and reconnects the line voltage.   __ Circuit Design by Basilio Simoes, ISA, Coimbra, Portugal

Protect Bu from 5v Swings -  11/14/02  EDN Design Ideas:  The circuit in Figure 1 automatically detects voltage and protects a bus, such as a 3.3 V-limited PCI bus, from 5V signal-level swings.  You can also use the circuit to determine bus-voltage swings within one bus-cycle for setting ap __ Circuit Design by Said Jackson, Equator Technologies Inc, Campbell, CA

Protect Computer's Input -  05/26/94 EDN Design Ideas:  The circuit in Fig 1 performs input protection, level translation, isolation, and debouncing.  The circuit allowed the output of a relay driver to connect to a computer even though the relay driver delivered a voltage as  __ Circuit Design by Ang Tzu Seng, Halliburton Drilling Systems, Singapore

Protect Power-LED Strings From Overcurrent -  06/23/11  EDN Design Ideas:  Add diodes and a transistor to a current mirror to prevent LED damage.  A common method for driving multiple power LEDs is through two parallel strings.  This inexpensive and less critical driver circuit can provide a lower voltage.  However, the driver circuit must deliver twice the current of other methods and needs a circuit that halves the current in the two strings, regardless of the LEDsí forward voltages.  The LEDsí forward-voltage tolerance is as high as 20%, and the voltages change with LED temperature and aging. __ Circuit Design by Luca Bruno, ITIS Hensemberger Monza, Lissone, Italy

Protect system from overheating -  11/08/01  EDN Design Ideas:  The two-chip circuit in Figure 1 provide as fan control and overtemperature warning and shutdown signals to protect systems from excessive heat.  The circuit monitors the temperature of the pc board and the die temperature of a CPU, an __ Circuit Design by Kerry Lacanette, Maxim Integrated Products, Sunnyvale, CA

Protect your boost converter -  EDN Design Ideas:  01/10/2017    This Design idea addresses boost convertersí inherent short-circuit vulnerability while also providing reverse-polarity protection __ Circuit Design by T A Babu

Protected 1A Automotive Solenoid Driver with Overvoltage Shutdown -  The LT1910 is a high side gate driver that allows the use of low cost N-channel power MOSFETs for high side switching applications.  it contains a completely self-contained charge pump to fully enhance an N-channel MOSFET switch with no external components.  __ Linear Technology/Analog Devices App Note, Apr 5th 2010

Protecting & Monitoring Hot Swappable Cards in High Availability Systems -  DN360 Design Notes__ Linear Technology/Analog Devices

Protection covers a wide range -  07/17/97 EDN Design Ideas:  Even if you take all the appropriate precautions to prevent transient feedthrough from the main power source, voltage transients can sometimes bypass all the safeguards and damage products and equipment.  Protecting all products under test in a lab is difficult because of the many types of products and the associated multitude of biasing requirements.  For this application, a suitable overvoltage- and transient-protection circuit needs to operate from about 3 to 95V and from a few microamps to several amps, preferably without the aid of additional power supplies. __ Circuit Design by y Lee R Watkins, Motorola Inc, Phoenix, AZ

Protection for Your Electrical Appliances -  Here is a very low-cost circuit to save your electrically operated appliances, such as TV, tape recorder, refrigerator, and other instruments during sudden tripping and resumption of mains supply.  Appliances like...__ Electronics Projects for You

Protection from Overvoltage & Overcurrent -  The LTC4361 overvoltage/overcurrent protection controller safeguards 2.5V to 5.5V systems from input supply overvoltage.  it is designed for portable devices with multiple power supply options including wall adaptors, car battery adaptors and USB ports.  The LTC4361 controls an external N-channel MOSFET in series with the__ Linear Technology/Analog Devices App Note, Apr 26th 2010

Protection of USB Port from Overvoltage & Overcurrent -  The LTC4362 monolithic overvoltage/overcurrent protector safeguards 2.5V to 5.5V systems from power supply overvoltage.  it is designed for portable devices with multiple power supply options including wall adaptors, car battery adaptors and USB ports.  __ Linear Technology/Analog Devices App Note, Jul 8th 2011

Protects FPGAS from Killer Spikes -  04/23/98 EDN Design Ideas:  A project using Xilinx FPGAs brought an interesting problem to light.  When you turn on the board, one FPGA in three succumbs to this problem.  A lot of frustration and testing uncovered a negative-going spike (Figure 1) in the 5V li __ Circuit Design by Nelson Nguyen, Anritsu Corp, Morgan Hill, CA

Protects from Battery Polarity Reversal -  This simple circuit can protect a sensitive electronic circuit from an accidental connection of a battery with a reversed polarity.  The N-channel FET connects the electronic device to the battery only when the polarity is correct.  The circuit shown was . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2002

Provide Flexible Gain Ranges -  06/21/01 EDN Design Ideas:  Certain designs need a programmable-gain amplifier with a wide gain range and high accuracy and common-mode rejection.  Usually, itís wise to exploit a programmable-gain instrumentation amplifier, such __ Circuit Design by Luo BenCheng, Chinese Academy of Sciences, Beijing, China

Provide Reverse-Battery Protection -  12/21/00 EDN Design Ideas:  A universal problem in battery-operated devices is the threat of damage when an end user (never an engineer) inserts the battery backward.  You can avoid damage by inserting a single diode or by using a diode-bridge configuration, but those fixes waste power and reduce the supply voltage by adding one or two diode drops between the battery and the supply rail.  An alternative solution not only protects against battery-reversal damage, but also automatically corrects the reversal (Figure 1).   __ Circuit Design by John Guy, Maxim Integrated Products, Sunnyvale, CA

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Safety / Protection:  # - G        H - Q        R - Z


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