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Simple & effective inrush current limiter stops surges - 08/02/07 EDN Design Idea Active circuit and relay replace loss y
negative-temperature-coefficient thermistor. Offline power supplies that drive loads of 200W and more require
inrush-current limiters. Unrestricted inrush currents can reach hundreds of Amperes, which may damage the line
rectifier, open the fuse and input-filter inductors, and damage the PFC (power-factor-correction) filter
capacitors. A simple method of limiting the inrush current uses an NTC (negative-thermal-coefficient) thermistor
that connects in series with the supply line. . . [by Gregory Mirsky]
Simple and effective inrush-current limiter stops surges - 08/02/07 EDN Design Idea Active circuit and relay replace loss
negative-temperature-coefficient thermistor. . . [by Gregory Mirsky, Juno Lighting Group, ModuLight Division,
Des Plaines, IL]
Simple warning signal - Flashing LEDs can be used to create the impression that an alarm has been fitted. Or they
can be used in conjunction with a real alarm - to warn-off a potential thief. These three small circuits will
flash anything from a single LED - up to 90 LEDs and beyond - with a variety of speeds and patterns. . . .
[Circuit design by Ron J.]
Soft limiter for oscillator circuits uses emitter-degenerated differential pair - 10/12/06 EDN Design Idea Phase-shift network plus a few active components yields
low-distortion output - Most oscillator circuits include a nonlinear Amplitude control that sustains oscillations
at a desired Amplitude with minimum output distortion. One . . . [by Douglas Sudjian, Resonext Communications
Inc, San Jose, CA]
Soft Start - The circuit will limit the current through the supply wires to 5. 5A for about 1. 5sec.
After that time the relay will close and the current flow won't be restricted anymore. This is a very interesting
circuit if you have a large toroid with big electrolytic caps connected to the power supply, since these will act
like short circuits for a small amount of time if they start charging. . . .
Soft-limiter circuit forms basis of simple AM modulator - 09/03/07 EDN Design Idea Inserting diodes biased by reference voltages in the feedback
loop of an op Amp yields a soft limiter that you can use as the basis of an AM modulator. . . [by Herminio
Martínez, Encarna García, and Juan Gámiz, Technical University of Catalonia, Barcelona, Spain]
Stereo Broadcast Limiter - Circuit for the Ramsey FM10a/FM25 Transmitter. . . [G. Forrest Cook]
Stereo Limiter - Stereo Broadcast Limiter Circuit for Ramsey. . . .
Supercapacitor
Voltage Limiting Circuit - Supercapacitors are working
their way into more and more applications where electrical energy needs to be stored. These robust devices can be
charged and discharged 1000s of times and will typically outlast a battery . . . [Circuit by David Johnson P.E.,
03/27/10]
Thermocouple Temperature
Activates Relay - Voltage from a high temperature
thermocouple activates a relay when the sensor detects a temperature above 1000 degrees F . . . [Circuit by Dave
Johnson P.E., 07/09/06]
Threshold
Noise Reduction Using Models 32, 37 & 520 - Schematic
only, no circuit description included. . . [Application OpAmps Lab Inc.]
Ultrasound
Receiver-40Khz - A X100 transistor Amplifier is
followed by a zero cross detector circuit, using a voltage comparator. The output is a TTL logic signal,
corresponding to the received 40KHz signal . . . [Hobby Circuit designed by David A. Johnson P.E., 01/29/06]
Voltage Limiter Generates
Supplies That Improve Standard Diode Technique - Some
systems require a voltage limiter to protect the input circuit. Designers can connect diodes to V CC and Gnd to
create a simple solution (Fig. 1). This simplicity, however, comes at a. . . Electronic Design Europe 10.02.11
Yossi Barkan
Voltage Limiting sith a Supercapacitor - Supercapacitors are working their way into more and more applications where electrical
energy needs to be stored. These robust devices can be charged and discharged 1000s of times and will typically
outlast a battery . . . [Hobby Circuit designed by Dave Johnson P.E., 03/27/10] |
