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Opto-Isolator Coupler Circuits
Opto Isolators:   #'s - N      M - Z
 

Last Updated: October 24, 2017 02:55 PM


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

Opto (Analog) Isolator -  This is a circuit to use a standard, low quality opto isolator to transfer an analogue signal with reasonable linearity and without complicated feedback loops to monitor and linearise it.  The circuit was designed to interface a mains driven thryristor motor controller to low voltage analogue circuitry.  In this application you could isolate the thyristor controller with a transformer and earth one side of the motor, but you still have a potentially high voltage situation if there is a wiring fault or component failure.  Also motors and thyristor controllers are potentially good generators of noise: in a system which used several motor controllers it was considered essential to isolate the input signal!  __ Designed by Richard Torrens

Opto Compressor/Limiter Side Chain with Gain Reduction Metering -  Circuit Diagram Only __  Contact:  info @ forsselltech . com

Opto Gerbers -  Circuit Diagram Only __  Contact:  info @ forsselltech . com

Opto isolated 1-Wire bus -  When building a 1-Wire MicroLAN, you can run into some difficulties in the way of safety and realibilty.  Reason is that the whole network has a galvanic coupling __ Designed by T. Rudolphi

Opto Reflective Sensor -  Here is a simple optoreflective sensor circuit based on TCRT5000 module.  It is ideal for projects like robotics, position sensing, proximity sensing, detection of reflective materials and many more.  Its range...__ Electronics Projects for You

Opto Stereo Link -  Circuit Diagram Only __  Contact:  info @ forsselltech . com

OptoCoupled Gate Detects Motor Operation -  02/02/98 EDN Design Ideas:  Most applications require redundant system checks to ensure that devices are operating as expected.  The circuit in Figure 1 detects when a PWM-controlled servo motor is running.  You can monitor the motor-running signal output with a CPU or tie the output to hardware that indicates a fault if the motor is running when it should be off.  The motor's output connects to input resistors RIN1 and RIN2.  The use of two resistors protects the motor or servo amplifier in the case of a short circuit.  RIN1 and RIN2 also serve as current-limiting resistors for the LED in the opto gate, IC2. __ Circuit Design by Malcolm Watts, Wellington Polytechnic, Wellington, New Zealand

Optocoupler extends high-side Current-sensorto 1 kV -  03/01/01 EDN Design Ideas:  The task of sensing dc current at high voltage is often problematic.  Most high-side current-sensing ICs available off the shelf are good only to 30 or 40V.  Combining an optocoupler with such an IC yields a sensing circuit in which the only limitation of the high-side voltage is the optocoupler's standoff voltage (Figure 1).   __ Circuit Design by Roger Griswold

Optocoupler isolates shift registers -  01/20/00 EDN Design Ideas:  Conventional shift registers, such as the 74HC595, require data-, clock-, and strobe-logic signals.  The circuit in Figure 1 needs only two logic signals to isolate and control shift-register devices.   __ Circuit Design by Jim Hartmann

Optocoupler simplifies power-line Monitoring -  10-Jan-02 EDN Design Ideas:  The use of a linear optocoupler and a capacitor-based power supply yields a simple, yet precise power-line-monitoring system.  The circuit in Figure 1 converts the 110V-ac power-line voltage to an ac output voltage centered at 2.5V, covering 0 to 5V.  The circuit isolates the output signal from the power line __ Circuit Design by Alfredo del Rio and Ana Cao y Paz, University of Vigo, Spain

Optocoupler speed-up also reduces power consumption -  EDN Design Ideas:  09/01/2014     Optocouplers tend to be sluggish, unless you have this circuit up your sleeve. __ Circuit Design by Marian Stofka

Optocouplers -  Find out more about optocouplers/optoisolators and their uses.   __ Designed by REUK-Renewable Energy UK website

Optocouplers are handy for Motor drive -  06/13/02 EDN Design Ideas:  Difference amplifier uses digital potentiometers - Figure 1a shows a latching circuit based on an optocoupler, IC1.  If the off switch remains closed, pressing the on switch powers the LED in the optocoupler.  Thus, the transistor in IC1 turns on.  You can now release the on switch, and the transistor remains on.  You must adapt the current-limiting resistor, R, to the power-supply voltage and the optocoupler's characteristics __ Circuit Design by Jean-Bernard Guiot, DCS AG, Allschwil, Switzerland

Optocouplers in intrinsic safety applications -  EDN Design Ideas:  02/16/2015   Intrinsic safety applications defined in IEC 60079-11 require careful selection of isolation components __ Circuit Design by Avago Tech Note

OptoElectronic Horizontal VBB Seismometer Figures -  xxx___ Designer?

Optoelectronic position control simplifies Motor Movements -  29-Apr-04 EDN Design Ideas:  The optoelectronic technique for achieving position control provide as an inexpensive, easy- to-design method of achieving simple, repeatable movement using fixed index points with linear- or rotary-motion components.  The simple, basic design in Figure 1 for sequential position control exploits the quick response time of a power op amp, working in tandem with a pair of photodiodes __ Circuit Design by Marie Rivera, Apex Microtechnology Corp, Tucson, AZ

Optoisolator Block Occupancy Detector -  This page is about a block occupancy detector that uses an optoisolator to electrically separate the track from the detector output. Four variations of the detector are shown. __ Designed by Rob Paisley

Optoisolators Compute Watts & Volt-Amperes -  02/21/08  EDN Design Ideas:  Relying on the dynamic conductance of optoisolators' junctions, simple optoisolator bridges compute the watts and volt-amperes of an ac load __ Circuit Design by W Stephen Woodward, Chapel Hill, NC

Phone wire, RJ-11 jacks & optocouplers build a bus -  12/07/04  EDN Design Ideas:  Although cutting-edge technology reaps publicity, the real world often runs on modest hardware that's just "good enough" for home automation, alarm systems, and equipment-monitoring applications.  Figure 1 shows a low-speed, multidro __ Circuit Design by Ernie Deel, EFD Systems, Marietta, GA

Photoelectric-FET Optocoupler as a Linear Voltage-Controlled Potentiometer -  01/19/12 EDN Design Ideas:  The circuit takes advantage of an identical photo-FET as a feedback element.  You can use a photoelectric FET as a variable resistor or a potentiometer in combination with a fixed resistor.  The H11F3M photoelectric FET has an isolation voltage of 7.5 kV, enabling you to safely control highvoltage circuit parameters.  The nonlinear-transfer characteristics of these devices are problematic, however (Figure 1).  To correct the nonlinearity, using a simple feedback mechanism as a potentiometer yields a linear response (Figure 2).  This circuit uses two photoelectric FETs—one for feedback and the other for applications requiring an isolated potentiometer.  You connect the inputs of the two photoelectric FETs in series to ensure the same amount of current for the input LEDs.   __ Circuit Design by Sajjad Haidar, University of British Columbia, Vancouver, BC, Canada

RS-232C circuit has galvanic isolation -  04-Feb-99 EDN Design Ideas:  NOTE :  File has several circuits, scroll to this one.  Galvanic, or electrical, isolation is a well-established technique for noise reduction and works best in computer and industrial systems in which noise can seriously affect data transfer.  Isolation removes ground-loop currents and their associated noise voltages from data lines __ Circuit Design by Design Idea byIoan Ciascai, REI Data, Napoca, Romania

RS-232-to-RS-232 Port Powered Optical Isolator -  Brochure with schematic in PDF format__ BB Electronic

Signal-Powered Linear Optocoupler Provides Isolated Control Signal -  23-Jul-09  EDN Design Ideas:  The circuit in Figure 1 provide as an isolated control voltage, such as 0 to 10V.  In the low part of the range, 0V to approximately 2V, the controlled device is off.  Therefore, the upper part of the range must be as linear as possible.  You can meet this requirement using a linear optocoupler, such as Vishay’s IL300 or Avago Technologies’ HCNR200 or HCNR201.    __ Circuit Design by Mitja Rihtarsic, ?kofja Loka, Slovenia

Simple Circuit Measures Optocoupler's Response Time -  09/08/11  EDN Design Ideas:  Measure the response speed of optocouplers in order to select matching devices.  You can use the circuit in this Design Idea to measure the attack and release times of photoresistor-type optocouplers (Figure 1).  Such devices often find use in audio compressors or volume-control circuits.  The design uses an oscillating Schmitt trigger with the optocoupler DUT (device under test) in the feedback loop.  The photoresistor and resistor R1 form a voltage divider that controls the input of the Schmitt trigger.   __ Circuit Design by Peter Demchenko, Vilnius, Lithuania

Smart gate-drive optocoupler with integrated flyback controller -  EDN Design Ideas:  03/13/2015   A smart gate-drive optocoupler for FETs & IGBTs is ideal for distributed power supplies, power inverters, motor drives, and more __ Circuit Design by Avago Tech Note

Temperature Sensor Uses I2C Isolator -  6-Jun-96 EDN Design Ideas:  You can couple an LM75 digital output-temperature sensor through an isolated I2C (interintegrated circuit] interface (see Reference] as shown in Figure 1.  Electrically isolating the sensor allows operation in situations prone to high common-mode voltages; it's also useful in breaking ground loops.  IC1 and IC2 comprise a bidirectional isolator __ Circuit Design by Jerry Steele, National Semiconductor, Tucson, AZ

TV/Radio Antenna Cable Galvanic Isolator -  A ground loop in your AV system caused by antenna connection or TV cable is very common if you have your computer connected to the same system.  This type of ground loop problem can be solved by using suitable isolation between your AV system and the antenna cable.  The simplest way to get rid of the hum is to disconnect the antenna cable from the AV system.  If you still want to watch cabe TV or listen to your radio an keep the system hum free then you have to install isolators to all those antenna cable connections your system has __ Designed by Tomi Engdahl

Use a Photoelectric-FET Optocoupler as a Linear Voltage-Controlled Potentiometer -  01/19/12 EDN Design Ideas:  The circuit takes advantage of an identical photo-FET as a feedback element.  You can use a photoelectric FET as a variable resistor or a potentiometer in combination with a fixed resistor.  The H11F3M photoelectric FET has an isolation voltage of 7.5 kV, enabling you to safely control highvoltage circuit parameters.  The nonlinear-transfer characteristics of these devices are problematic, however (Figure 1).  To correct the nonlinearity, using a simple feedback mechanism as a potentiometer yields a linear response (Figure 2).  This circuit uses two photoelectric FETs—one for feedback and the other for applications requiring an isolated potentiometer.  You connect the inputs of the two photoelectric FETs in series to ensure the same amount of current for the input LEDs.   __ Circuit Design by Sajjad Haidar, University of British Columbia, Vancouver, BC, Canada

Variable HV power supply employs photovoltaic optocoupler -  07/14/14 EDN Design Ideas:  This unusual topology saved the day when a higher-voltage variable supply was needed.   __ Circuit Design by sajjad Haidar

Widen Opt coupler’ Response -  12/21/95 EDN Design Ideas:  Isolation amplifiers provide insulation for low-frequency analog signals at a high cost.  Optocouplers cost less and are widely used with digital signals.  However, you have to factor in limitations from distortion and bandwidth restrictions when using optocouplers.  The bandwidth limits result from a declining current-transfer ratio as a function of frequency.  You can use feedback techniques to improve the linearity, but the circuits are usually complex.  The circuit in Figure 1, which applies current drive to the optocoupler diode, improves bandwidth and allows easy frequency-response equalization. __ Circuit Design by Ferran Silva, Marcos Quílez, and Ramón Bragós, Universitat Politècnica de Catalunya Barcelona, Spain


Opto Isolators:    #'s - N      M - Z

 


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