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Discriminator Circuits
Discriminators:  #'s - D     E - Z

 

Last Updated: December 31, 2017 06:48 AM

Circuits Designed by Dave Johnson, P.E.

1us Light Pulse Discriminator -  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.  The circuit is designed to process a pulse frequency . . . Hobby Circuit designed by David A. Johnson P.E.-March, 1999

40Khz Ultrasound Receiver 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. . . Circuit by David Johnson P.E.-January, 2006

AC Peak Detector that is Precise This unique circuit uses a very inexpensive voltage comparator to form a peak detector.  The DC voltage produced tracks the positive peak of the input signal.  It works from about ten millivolts to about 10 volts peak to peak.  The maximum frequency is about . . . Hobby Circuit designed by David Johnson P.E.-February, 2002

Acceptable Voltage Indictor I have used this circuit many times in custom test fixtures where a simple go-no go indication was needed.  The circuit can also be used to adjust a particular voltage be within specific high or low limits.  The three LEDs will indicate if the voltage is. . . Circuit by David Johnson P.E.-February, 2002

Amplifier for a Xenon Lamp Flash Detector  - This circuit has a very low standby current requirement yet has very high sensitivity toward the light flashes from a xenon lamp.  When connected to a flip/flop it can serve as an on on/off Controller. . . Circuit by David Johnson P.E.-February, 2002

Battery Charge Current Indicator This circuit turns on a LED whenever it detects at least 25ma of battery charge current. . . Circuit by David Johnson P.E.-July, 2006

Circuit indicates Battery Charging Current Anyone who has ever had a shocking experience on an especially dry day is acutely aware of the kinds of high voltage that can be generated from a simple walk across a carpeted floor.  Those same finger to metal sparks can destroy or disrupt sensitive elect . . . Hobby Circuit designed by David A. Johnson P.E.-January, 2011

Cooling Fan Thermostat (12v) This circuit will turn on a 12v DC powered cooling fan when the air temperature reaches a certain high temperature and will keep the fan turned on until the temperature drops below a second lower level.  Both the high and low temperatures are both adjustable . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2011

DC Current Indicator #4 The circuit below uses some common components to turn on an LED whenever DC current above a certain level is detected.  The circuit uses a very popular LM393 dual voltage comparator from National Semiconductor and a common 1N4148 signal diode.  The diode. . . Circuit by Dave Johnson P.E.-October, 2005

DC Current Indicator 6 The circuit below is a simple way to indicate when DC current is flowing through a wire.  The circuit is designed so it will turn on a LED indicator light, whenever the voltage drop across a shunt resistor exceeds about 0.1volts.  The value of the resist. . . Circuit by David A. Johnson P.E.-October, 2005

Detect Short Xenon Lamp Flashes This circuit uses a small 2.5mm square photo diode in conjunction with a 100mH coil to detect the short light flashes from a xenon lamp.  The coil makes the circuit immune to normal room lights.  Its 10mv sensitivity can detect light flashes from a range of over 100 feet. . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2002

Detect the narrow 1uS pulses 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.  The circuit is designed to process a pulse frequency. . . Circuit by Dave Johnson P.E.-March, 1999


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

1-Shot Provides Frequency Discrimination -  05/01/03  EDN-Design Ideas 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__ Circuit Design by Victor Aksenenka, CSRI Elektropribor, St Petersburg, Russia

1us Light Pulse Discriminator -  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.  The circuit is designed to process a pulse frequency . . . Hobby Circuit designed by David A. Johnson P.E.-March, 1999

2 buttons provide safe start -  07/06/00 EDN-Design Ideas The circuit in Figure 1 provIdeas 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'__ Circuit Design by   Vincent Himpe, Alcatel Microelectronics, Desselgem, Belgium

2-Wire Thermistor 0°C to 100°C Temperature Transducer with 4mA to 20mA Output -  The LTC1040 is a monolithic CMOS dual comparator manufactured using Linear Technology’s enhanced LTCMOS TM silicon gate process.  Extremely low operating power levels are achieved by internally switching the comparator ON for short periods of time.  The CMOS output logic holds the output information continuously while not consuming __ Linear Technology/Analog Devices App Note, Mar 30th 2010

40Khz Ultrasound Receiver -  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. . . Circuit by David Johnson P.E.-January, 2006

5V Powered Thermistor Heating/Cooling Automatic Thermostat -  The LTC1040 is a monolithic CMOS dual comparator manufactured using Linear Technology’s enhanced LTCMOS TM silicon gate process.  Extremely low operating power levels are achieved by internally switching the comparator ON for short periods of time.  The CMOS output logic holds the output information continuously while not consuming __ Linear Technology/Analog Devices App Note, Mar 30th 2010

A Seven-Nanosecond Comparator for Single Supply Operation -  Linear Technology AN72 __ Designed by Jim WilliamsMay 1st, 1998

Absolute Value (Full-Wave Rectifier) -  For negative inputs, the first section operates as a closed-loop inverter   (A=-1) and the second stage is simply a buffer for the positive output.  When the input signal is positive, the first opamp output remains saturated near ground and the diode becomes high-impedance, allowing the signal to pass directly to the buffer stage non inverted.  The composite effect is a full-wave rectified waveform at the output of the buffer.  __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Absolute-value comparator touts accuracy, size -  03/07/02  EDN-Design Ideas 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 wi__ Circuit Design by Teno Cipri, Engineering Expressions Consulting, Sunnyvale, CA

Absolute-Value Delivers High Bandwidth -  15-May-03 EDN-Design Ideas 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,__ Circuit Design by Ron Mancini, Texas Instruments, Bushnell, FL

AC Peak Detector that is Precise -  This unique circuit uses a very inexpensive voltage comparator to form a peak detector.  The DC voltage produced tracks the positive peak of the input signal.  It works from about ten millivolts to about 10 volts peak to peak.  The maximum frequency is about . . . Hobby Circuit designed by David Johnson P.E.-February, 2002

Acceptable Voltage Indictor -  I have used this circuit many times in custom test fixtures where a simple go-no go indication was needed.  The circuit can also be used to adjust a particular voltage be within specific high or low limits.  The three LEDs will indicate if the voltage is. . . Circuit by David Johnson P.E.-February, 2002

Add Hysteresis to a Voltage Comparator -  4-Mar-10 EDN-Design Ideas 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 noninverting 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__ Circuit Design by Luca Bruno, ITIS Hensemberger Monza, Lissone, Italy

Amplifier for a Xenon Lamp Flash Detector  -  This circuit has a very low standby current requirement yet has very high sensitivity toward the light flashes from a xenon lamp.  When connected to a flip/flop it can serve as an on on/off Controller. . . Circuit by David Johnson P.E.-February, 2002

AN72A Seven-Nanosecond Comparator for Single Supply Operation -  Linear Technology AN72 __ Designed by Jim WilliamsMay 1st, 1998

Battery Charge Current Indicator -  This circuit turns on a LED whenever it detects at least 25ma of battery charge current. . . Circuit by David Johnson P.E.-July, 2006

Circuit discriminates & recovers noisy pulses -  EDN-Design Ideas 09/29/2014     Noisy pulse trains with widely-varying amplitude are recovered with this DI circuit.  Think transducers…__ Circuit Design by Vladimir Rentyuk

Circuit indicates Battery Charging Current -  Anyone who has ever had a shocking experience on an especially dry day is acutely aware of the kinds of high voltage that can be generated from a simple walk across a carpeted floor.  Those same finger to metal sparks can destroy or disrupt sensitive elect . . . Hobby Circuit designed by David A. Johnson P.E.-January, 2011

Clock Tunable, Filter Based Sine Wave Generator -  A feedback loop enclosed resonator can be made to oscillate.  This circuit’s sine wave generator takes advantage of this and eliminates the need for an amplitude control loop.  This circuit, a mildly modified form of the Regan resonant bandpass loop, is clock tunable and produces sine and cosine outputs.  __ Linear Technology/Analog Devices App Note, Mar 26th 2010

Comparator provides stable hysteresis -  03/18/99 EDN-Design Ideas Unless a voltage-comparator circuitis sampling an extremely clean signal, the comparator always requires some hysteresis.  Traditional comparator circuits obtain the required hysteresis by using positive feedback derived from the ratio of two resistors.  The voltage at the noninverting input is the superposition of a fraction of the input and output voltages, each divided by its respective resistor ratio.  With an inverting comparator, the noninverting input usually connects to a voltage reference with reasonably low impedance, and you can choose the hysteresis-setting resistors without concern for loading.  __ Circuit Design by Fernando Garcia, Lucent Technologies, Brownsville, TX

Comparator uses signal-dependent hysteresis -  EDN-Design Ideas March 26, 1998    [ NOTE : File has multiple design, scroll for this one.]  Sometimes, you need to distinguish between two voltages, using some hysteresis in the decision. When the levels of the compared signals vary over a wide range (for example, a few orders of magnitude), the hysteresis width should vary similarly to ensure a constant ratio between hysteresis width and signal level__ Circuit Design by P Krehlik and L Sliwczynski, University of Mining and Metallurgy, Krakow, Poland

Comparators form 3 to 5V or 5 to 3V translator/transceive -  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__ Circuit Design by Robert Hanrahan,  National Semiconductor, Woodcliff Lake, NJ

Cooling Fan Thermostat (12v) -  This circuit will turn on a 12v DC powered cooling fan when the air temperature reaches a certain high temperature and will keep the fan turned on until the temperature drops below a second lower level.  Both the high and low temperatures are both adjustable . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2011

DC Current Indicator #4 -  The circuit below uses some common components to turn on an LED whenever DC current above a certain level is detected.  The circuit uses a very popular LM393 dual voltage comparator from National Semiconductor and a common 1N4148 signal diode.  The diode. . . Circuit by Dave Johnson P.E.-October, 2005

DC Current Indicator 6 -  The circuit below is a simple way to indicate when DC current is flowing through a wire.  The circuit is designed so it will turn on a LED indicator light, whenever the voltage drop across a shunt resistor exceeds about 0.1volts.  The value of the resist. . . Circuit by David A. Johnson P.E.-October, 2005

Design an Efficient Reset -  1-May-03 EDN-Design Ideas 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__ Circuit Design by Guillermo Bosque, Asesoría e Integracion de Tecnologías, Urduliz, Spain

Design low-duty-cycle timers -  08/22/02 EDN-Design Ideas 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__ Circuit Design by Phil Rogers, Texas Instruments Inc, Rockwall, TX

Detect Short Xenon Lamp Flashes -  This circuit uses a small 2.5mm square photo diode in conjunction with a 100mH coil to detect the short light flashes from a xenon lamp.  The coil makes the circuit immune to normal room lights.  Its 10mv sensitivity can detect light flashes from a range of over 100 feet. . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2002

Detect the narrow 1uS pulses -  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.  The circuit is designed to process a pulse frequency. . . Circuit by Dave Johnson P.E.-March, 1999

Double Dual Limit Window Comparator -  This window comparator circuit has 4 limints, 2 lower limits and 2 upper limits, which can produce up to 4 separate outputs, each dedicated to a warning, an alarm or a control condition.___ Advanced Linear Devices, Inc

Dual comparators stabilize proximity Detector -  02/16/98 EDN-Design Ideas (File contains several circuits, scroll to find this one)__ Circuit Design by Arthur Harrison, US Army Research Laboratory, Adelphi, MD, and Joseph Stern, Maxim Integrated Products, Sunnyvale, CA

Dual Limit Microvolt Comparator -  Low offset precision amplifiers make very accurate comparators.  This is a window comparator when an output LED indicates that the input is outside of the window.  Hysteresis to ensure smooth switching is provided to one of the offset nulling terminals with minimal impact on offset and therefore threshold accuracy.  __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Dual Output, Buffered Reference (On Single 3V Supply) -  The amplifier configuration establishes the reference voltage across the 75k resistor.  A fixed current is then forced into the 46.4k resistor and sets the lower output voltage.  The upper voltage output is greater than the lower voltage output by the reference voltage.  __ Linear Technology/Analog Devices App Note, Jun 21, 2011


Discriminators:  #'s - D     E - Z


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