Electronic Circuits and Tutorials
Electronic Schematics - D

Discriminator Circuits

Absolute-value comparator touts accuracy, size -  7-Mar-02 Issue of EDN  A typical window comparator uses two comparators and a single op amp to determine whether a voltage is inside or outside a boundary region. Figure 1 shows a typical implementation. IC1 is an inverting op amp with a gain of –1. VREF and –VREF create the window limits. When VIN becomes positive than VREF, the output of IC2A goes low..... [Design Idea by Teno Cipri, Engineering Expressions Consulting, Sunnyvale, CA]

Add hysteresis to a voltage comparator -  4-Mar-10 Issue of EDN  Positive feedback is a typical technique for distributing hysteresis around a comparator, provided that you have a resistive path between the comparator's output and the non-inverting input. Positive feedback forms two threshold voltages that have (or assume] fixed values. In addition, they depend on the saturation values of the comparator's output stage..... [Design Idea by Luca Bruno, ITIS Hensemberger Monza, Lissone, Italy]

An IC Voltage Comparator for High Impedance Circuitry -  National Semiconductor Application Note

AN-41: Precision IC Comparator Runs from +5V Logic Supply -  National Semiconductor Application Note

AN-87: Comparing the High Speed Comparators -  National Semiconductor Application Note

Applications of the LM392 Comparator Opamp Ic -  National Semiconductor Application Note 04-Nov-1995

Circuit Techniques for Avoiding Oscillations in Comparator Applications -  National Semiconductor Application Note

Comparator provides stable hysteresis -  03/18/99 EDN-Design Ideas Unless a voltage-comparator circuit is sampling an extremely  clean signal, the comparator  always requires some hysteresis.   Traditional comparator circuits ….PDF contains multiple circuits, scroll to find this circuit..... [Design Idea by Fernando Garcia, Lucent Technologies, Brownsville, TX]

Comparator uses Signal Dependent Hysteresis -  03/26/98 EDN-Design Ideas..... A project posed the challenge of replacing existing analog potentiometers (used to set brightness and contrast levels]in video monitors with digitally controlled potentiometers. The different brands and models of monitors presented widely varying voltages across the potentiometers..... [Design Idea by P Krehlik and L Sliwczynski, University of Mining and Metallurgy, Krakow, Poland]

Comparators Form 3 to 5 Volt or 5 to 3 Volt Translator/Transceiver -  09/02/96 EDN-Design Ideas.....In many recent systems, you often need to interface 3V signals with higher voltages within the system. In some cases, it's necessary to interconnect 3 and 5V open-collector transceivers.Figure 1 shows one example, in which multiple multidrop communications devices interconnect. In systems where no control lines are available for interfacing, the..... EDN is migrating links. This link is not verified.  Google the "title" EDN for new link.

Comparing the High Speed Comparators -  National Semiconductor Application Note

Design an efficient reset circuit -  1-May-03 Issue of EDN  When you work with microprocessors, you must ensure that when the power-supply voltage fluctuates to the minimum permissible level, VL, that the processor's ALU continues to operate normally. Also, when you switch on the power supply, the ALU must operate normally when the supply voltage equals or exceeds a certain high level, VH..... [Design Idea by Guillermo Bosque, Asesoría e Integracion de Tecnologías, Urduliz, Spain]

Design low-duty-cycle timer circuits -  22-Aug-02 Issue of EDN  Designing astable circuits using the industry-standard 555 timer is a straightforward process when duty cycles are 50% or greater. However, you must overcome the many pitfalls of low-duty-cycle circuits to arrive at a desired result. Using only ideal components eases the design, but the components themselves are hard to obtain..... [Design Idea by Phil Rogers, Texas Instruments Inc, Rockwall, TX]

Dual comparators stabilize proximity detector -  02/16/98 EDN-Design Ideas.....In the proximity detector of Figure 1, a 4-in.-sq piece of copper-plated pc board serves as an antenna that forms one plate of a capacitor. An approaching (grounded] person serves as the other plate, producing a capacitance.....File has many circuits, scroll to find this one..... [Design Idea by Arthur Harrison, US Army Research Laboratory, Adelphi, MD, and Joseph Stern, Maxim Integrated Products, Sunnyvale, CA]

Electronic fuse emulates fast- or slow-blow fuses -  11/09/00 EDN-Design Ideas.....The electronic-fuse circuit in Figure 1 combines the properties of a current transducer and a solid-state relay to disconnect low power at preset levels.Using this circuit lets….PDF contains multiple circuits, scroll to find the one of interest..... [Design Idea by John A Hasse, Colorado State University, Fort Collins, CO]

Expanded-scale indicator revisited -  8-Aug-02 Issue of EDN  The visualization aid that a previous Design Idea describes allows only the expansion of the upper end of the scale (Reference 1]. But what can you do if, according to your project requirements, you need to expand the middle region of the scale? Figure 1a illustrates the challenge. A voltmeter comprises a 100-µA dc meter and a series resistor..... [Design Idea by Abel Raynus, Armatron International Inc, Melrose, MA]

Fast Voltage Comparators with Low Input Current -  National Semiconductor Application Notes,28-Jun-1996

LB-12: Linear Brief 12 an IC Voltage Comparator for High Impedance Circuitry -  National Semiconductor Application Note

LB-32: Linear Brief 32 MicroVolt Comparator -  National Semiconductor Application Note

LB-39: Linear Brief 39 Circuit Techniques for Avoiding Oscillations in Comparator Applications -  National Semiconductor Application Note

LB-6: Fast Voltage Comparators with Low Input Current -  National Semiconductor Application Note

Light Sensor With Hysteresis -  It is quite a simple circuit but rather more effective than the one using the 741. It uses a simple comparator LM311 as the master piece.  This comparator is powered from a +12V DC supply and does not require negative supply to work efficiently. The feedback given to the comparator provides some hysteresis and the potentiometer allows to adjust the sensitivity of the detector for darkness. I am quite sure you could inverse R1 and R2 positions to inverse the action of the detector but I haven't tried it! …. [By Frank Rivard]

LM139/LM239/LM339 a Quad of Independently Functioning Comparators -  National Semiconductor Application Note 24-Feb-1999

Low Voltage Alarm -  NE555 Low Voltage Battery Disconnect Circuit… [design by Arron Cake]

MicroVolt Comparator -  National Semiconductor Application Notes first published 28-Jun-1996

Missing codes Tester checks 16 Bit ADC in 7 sec -  06/10/99 EDN-Design Ideas.....As the resolution of ADCs increases from 12 to 16 bits and higher, the difficulty in testing the"nomissing-codes"specification grows proportionately. To fully guarantee no missing codes for a 16-bit ADC requires testing all 2 16-1 possible output..... EDN is migrating links. This link is not verified.  Search the "title" + EDN for new link.

Missing Pulse Detector Basic -  This circuit is a one-shot that is continually retriggered by incoming pulses…. [Tony van Roon's circuit]

One-shot provides frequency discrimination -  1-May-03 Issue of EDN  You use a frequency discriminator to compare one signal frequency with another one. A functional feature, retriggering, of a monostable, one-shot 74xx123 multivibrator can yield frequency discrimination. Figure 1 shows a frequency discriminator that determines the relation of input-pulse frequency to a reference frequency..... [Design Idea by Victor Aksenenka, CSRI Elektropribor, St Petersburg, Russia]

Precision IC Comparator Runs from Plus 5 Volt Logic Supply -  National Semiconductor Application Note 04-Nov-1995

Schottky diodes improve comparator’s transient response -  21-Jan-10 Issue of EDN  Two Schottky barrier diodes clamp error voltages, cut output glitches..... [Design Idea by Marián Stofka, Slovak University of Technology, Bratislava, Slovakia]

Synchronized Window Comparator Eliminates Error -  05/11/95 EDN-Design Ideas.....Precision A/D converters need a window comparator. The window comparator in Fig 1a is synchronized to the clock signal.  This synchronization eliminates errors that could arise when the input signal crosses the high or low threshold (Fig 1b]unsynchronized to clock. In operation, comparator IC1A sets flip-flop IC2..... [Design Idea by Sergey Velichko, Consultant, Bosie, ID]

Two Buttons Provide Safe Start -  07/06/00 EDN-Design Ideas.....The circuit in Figure 1 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 relay'..... [Design Idea by Vincent Himpe, Alcatel Microelectronics, Desselgem, BelgiumVincent Himpe, Alcatel Microelectronics, Desselgem, Belgium]

Voltage Comaparator and Q Multiplier make a stable Sine Wave Oscillator -  It is a known fact that sinusoidal oscillators must rely on the action of some amplitude limiting mechanism in order to achieve good frequency and amplitude stabilities.  Likewise, accurate loop-gain control and high-Q tuned circuits are required for the attainment of low-distortion output levels.

Voltage Comparator -  This experiment only requires a single operational amplifier. The model 1458 and 353 are both "dual" op-amp units, with two complete amplifier circuits housed in the same 8-pin DIP package.

Voltage Comparator Forms Pulse Demodulator -  11/19/98 EDN-Design Ideas.....To process low-level ultrasound or radio-range pulses, you need a signal-conditioning amplifier followed by a pulse demodulator to translate the signals to dc pulses. Traditionally, you would use a diode-demodulator configuration (for example, the circuit in Figure 1a] with one stage of a single-supply op amp.....scroll to find this one..... [Design Idea by [Abel Raynus, Armatron International, Melrose, MA]

Voltage Comparator Switch -  This circuit will provide an indication whenever the input voltage differs from two defined limits, V1 and V2. The supply voltage, Vcc must be higher than the highest input voltage by at least 2 volts. One application here is to monitor a 12V car battery.

1us Light Pulse Discriminator Plus F to V Converter -  This circuit is designed to detect the narrow 1uS pulses produced by the above amplifier circuit. The clean logic type pulses produced by the discriminator are then sent to a frequency to voltage converter...... [Designed by David A. Johnson]

A Seven Nanosecond Comparator for Single Supply Operation -  AN72 Linear Technology AN72 is an extensive discussion of  causes and cures of problems in very high speed comparator circuits. A separate applications section uses  7ns LT1394 in V-to-F converters, crystal oscillators, clock skew generators, triggers, sampling configurations and a nanosecond pulse stretcher. Appendices cover related topics.

Absolute-value circuit delivers high bandwidth -  15-May-03 Issue of EDN  Most absolute-value circuits have limited bandwidth and high component count, and they require several matched resistors. The circuit in Figure 1 uses three fewer components than most absolute-value circuits require, and only two of the resistors must have 1% tolerance to obtain 1% accuracy.  This circuit's output voltage is an accurate representation of the absolute value of the input signal,..... [Design Idea by Ron Mancini, Texas Instruments, Bushnell, FL]

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