Zero-crossing refers to detecting the point at which a sine wave reaches the zero point of magnitude. In AC circuits it corresponds to the point at which no voltage is present so switching at that point reduces interference.

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Zero-Cross detector problem

I am really in a tough situation and need very serious elaborative help with this. Almost like spoon-feeding. It's been days I've been trying to get my zero cross detector (and the triac dimmer) to ...
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Is a “self-bootstrapping” zero-crossing AC power switch possible?

As a follow-up to this prior question I'm looking for a zero-crossing mains (120V) power switching solution to mitigate the bounce-related EMI I'm getting using the "stock" traditional ON/OFF toggle ...
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Optoisolator, did I connected it right? (Arduino Uno)

Here is my connection for optoisolator, 2 wires, yellow and red are for AC current. Other 3 in my arduino, orange pin 2, blue ground and red 5V power. And ...
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149 views

How to test if zero crossing is working?

I used circuit like this: On led I get: 3.3 mA and 1.3V What is the best way to test if zero crossing works with arduino or multimetar?
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190 views

How Zero Crossing optoisolator to work with 220VAC?

I want to use a H11AA1 to detect Zero Crossing, but I am not sure how circuit should look like. How much voltage should LED receive inside H11AA1? Here is datasheet: ...
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70 views

Automotive alternator: zero crossing detection (frequency)

I need to detect voltage frequency of an automotive alternator (before rectification). Alternator is a 3-phase generator, I will be looking at one of the phases. The voltage frequency never exceeds ...
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83 views

Power Gating a Comparator

I am using a comparator (TS3021) as a zero crossing detector (ZCD). The ZCD toggles its output based on the zero crossings of a sine wave generated across a transformer coil. One end of the coil is ...
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131 views

Automatic calibration of a zero cross detector latency

I have a circuit similar to this one (different component values, different uC): I expect a large phase error in the ZCD. The load is purely resistive and of unknown value between 100W and 1000W. ...
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165 views

Would this lazy zero cross detector work?

Task: Design a ZCD for 230VAC to be interfaced to an atmega168, 5VDC. The pictured optocoupler is SFH620A-3. I have on hand 1/4W E24 resistors. I am extremely lazy and want to go away with as ...
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202 views

Using zero crossing detector for brightness control of several loads

Zero cross detector(IC H11AA1) generates a pulse exactly at zero crossing of AC wave. I am trying to control the brightness of several bulbs(nearly 48 loads). I have 5 different states for them. At ...
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159 views

Maximum voltage allowed in trigger pin of 555 bistable

I want to measure the frequency of a bicycle hub generator, consisting of a variable AC voltage output. Nominally, the RMS voltage is 6V, but with no load attached the voltage peaks can be tens of ...
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113 views

Step-down converter and ceramic minimum ESR capacitor

I'm building a step-down converter, based on the TI TPS5450, which provides a reference design and various considerations on the capacitor. Even on the minimum ESR required. But when states "The ...
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181 views

Live switching AC loads with TRIACs or SSR

I have been designing a system whose purpose is to provide high reliability to a set of outlets (8), it takes to inputs of diffrent phases mains current, now the purpose of the system is that if the ...
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790 views

Why do we prefer zero-crossing optotriacs for driving triacs?

I usually see a special type of optotriac which has internal zero-crossing detection circuit in it. This type of optotriac is generally used for driving triacs. But, I don't understand its necessity. ...
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383 views

How to correctly simulate Zero Cross Detector Circuit?

I am trying to simulate a circuit for Zero Cross Detection. The end goal is triac phase control. My simulation using proteus hangs up and with message "Simulation is not running in real time" and ...
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329 views

Arduino Dimmer Shield Schematics Interpretation

I've read so much about Thyristors, Triacs and Rectifiers on the last days that I'm almost understanding my schematic, but I'm not there yet - I need some help. Overview: I'm making a home automation ...
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279 views

Get the frequency of a three phase voltage without a PLL?

I would like to get the phase and therefore the frequency of a three phase voltage, and with using a simple transformation (Clarke). so I get a stationary alpha - beta voltages. Then I will use an ...
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3answers
856 views

Will this zero-cross detection circuit work?

I have a 10W SMPS circuit powering a home appliance like this: I need to extract a zero-crossing pulse from this circuit which would then be fed to a micro-controller. To this end, I am considering ...
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Do I need zero-crossing detection for controlling a heater?

I need to control a heater element (about 500W) using arduino. For switching part I would go with zero-crossing SSR or zero-crossing optoisolator and triac (the second seems to be cheaper). The ...
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488 views

What's the purpose of the 1M resistor in this comparator circuit?

I find this circuit from ON Semiconductor's LM211 datasheet. There is a 1M resistor from negative power rail to the 'reference' input. ON doesn't describe the circuit's function. I think it's a ...
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3k views

How to sense the zero crossing of current?

I am trying to sense the power factor angle using microcontroller. Now the mechanism that I have thought it that Measure the zero crossing of voltage When the voltage zero is sensed, start the ...
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Zero crossing detector: do I really need the 7W resistor?

I am trying to provide zero crossing detection to my controller. Using the schematic below, I managed to generate square wave signal, representing positive v/s negative half-period. The problem is ...
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Arduino 230v Light bulb dimming

Hey guys i have done a lot of research and testing on different circuits for 230v(50hz) or 220v light dimming, but i cant get my arduino to dim my light. This is the last thing i tried. made this ...
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How do I select an optoisolator to both provide zero crossing to a uC and controll a triac?

This application note states that zero crossing detection can be achieved in an AVR with just a couple of resistors. However, it forgoes galvanic isolation and this is not acceptable for me. I would ...
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4answers
9k views

TRIAC dimmer, circuit design help (resistive load)

Okay guys, I've been tasked with making a light-dimming control system for a 240V heat lamp dissipating around 250W. I need to adjust the heat output on the lamp by control from a microprocessor. I'm ...
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How to calculate the zero crossing offset in a capacitive transformerless power supply

I'm working on a circuit powered by a capacitive transformerless power supply, that is a microcontroller based triac-switching project for resistive loads. I've taken the basic design of the power ...
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26k views

Digital Dimmer With Microcontroller

I want to build a digital dimmer for resistive Loads. I have found this circuit for that: The input voltage is 220VAC 50Hz. The red box in the picture is for ...
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2k views

Zero Crossing Optoisolator in Multisim

I'm an electronics hobbist with relatively little experience and I'm playing around with Multisim to try to understand how to manipulate AC waveforms. Specifically, I would like to control the wave ...
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When should I fire the TRIAC's gate when controlling an inductive load (AC motor)?

I'm using a combination of opto-triac + TRIAC to control a 230V AC motor with a microcontroller. For detecting the zero-crossing of the voltage I'm using another optocoupler. I know that the AC ...
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2answers
2k views

What does 'random phase' means in a triac driver?

I'm using this triac driver to control a triac. In its datasheet it says 'provide random phase control of high current triacs [...]'. What does that mean? It doesn't have zero-crossing detection?
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Difference between Zero-Crossing Optoisolator and Regular Optoisolator

I am trying to find any documentation on what the purpose is of a Zero-Crossing Circuit TRIAC Optoisolator. The datasheets don't explain the concept well enough. If you do answer, please include ...
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1answer
9k views

How can I detect a power outage with a microcontroller?

I have the following power supply configuration: AC MAINS -> UPS -> 24V POWER SUPPLY -> 5V VOLTAGE REGULATOR -> PCB (microcontroller). What's the best solution to detect the power outage on the mains ...
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How do I read a datasheet for a solid state relay?

I'm looking to use several (12-18) solid state relays to control a set of water valves (24V AC solenoids, 20ma holding current, 40ma inrush current), and I'm having trouble finding suitable parts, ...
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How to use a phototriac coupler to trigger the main triac?

I have in my box of parts a phototriac coupler, namely a Sharp PC3SD21NTZ (datasheet), which is a zero cross type. I don't know how to use it, but I've been meaning to learn for a while. This part is ...
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7k views

120VAC 60Hz Zero Cross Detector

I'm designing a digital phase-controlled light dimmer, and I need a zero-crossing detector circuit. From what I've read, it's a bad idea to wire the AC main directly to the microcontroller through a ...
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5answers
3k views

detecting zero cross in ac?

I need to detect zero crossing for a soft starter. A long while ago, I have done it using a 1 Mega ohm resistor directly connected to micro controller at one side and live power at another side. I was ...