Questions tagged [zero-crossing]

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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29
votes
2answers
14k 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 ...
14
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5answers
5k 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 ...
12
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2answers
4k views

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, ...
11
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4answers
36k 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 ...
10
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3answers
14k views

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 ...
10
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4answers
17k 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 ...
8
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2answers
4k views

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 ...
8
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4answers
17k views

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 motor ...
6
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1answer
2k views

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 ...
5
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4answers
10k 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 ...
5
votes
3answers
911 views

Would I need a zero-crossing SSR for a reflow oven controller?

I'd like to follow this guide to create a reflow oven controller: https://apollo.open-resource.org/mission:resources:picoreflow But I am confused on the zero-crossing SSR. Does it need to be zero-...
5
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4answers
20k views

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 ...
4
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5answers
610 views

Will a low-pass filter make zero-crossing detection less precise?

In my application I need to sample a number of bipolar signals coming from piezo sensors, and detect their relative time difference (for multilateration based on difference time of arrival). I expect ...
4
votes
2answers
1k 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 ...
4
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2answers
3k 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?
4
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4answers
1k views

zero cross detector missing zero cross

I'm trying to make a zero cross detector. I used the schematic below as a reference.(schematic from http://microcontrollerslab.com/zero-crossing-detector-circuit-using-pic-microcontroller/) However ...
4
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3answers
10k views

A question on zero crossing versus random-fire SSRs

Figure 1. I have the above mechanism, where I control a single-phase fan motor's switch. I mean instead of a mechanical switch, an AC/DC SSR is switching ON or OFF from a remote place by a constant ...
4
votes
1answer
229 views

Why 2 zero-crossing detection circuits in heater?

I reverse engineered the power board of an electric heater. I think, I understand most aspects of this circuit. One thing is not entirely clear to me though: The circuit seems to have two distinct ...
4
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2answers
240 views

Art of Electronics zero-crossing circuit question

I'm trying to make sure I understand how this circuit works fairly well before I read on. Here is the diagram: Here are some of the things I am thinking about this circuit: Because input goes to ...
3
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2answers
5k views

Why is zero crossing detector is used in some AC control circuits?

Zero crossing occurs when the line voltage is changing its polarity, from positive to negative, or vice versa. What I understand is, to fire the triac properly the firing circuit and the AC line ...
3
votes
3answers
1k views

Zero-crossing detection

I'm doing a circuit that controls a charge for TRIAC, with zero detection. Whenever I tested the circuit, regardless of what I was sending from the microcontroller, TRIAC always sent all the current ...
3
votes
1answer
11k 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. ...
3
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3answers
3k 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 ...
3
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2answers
2k views

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 ...
3
votes
2answers
2k 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 ...
3
votes
1answer
553 views

Is it possible to use Microchip's ZCD (Zero cross detect) circuitry in an isolated SMPS?

Let's say you have a device which is fed by AC line voltage and features an isolated SMPS. The switcher outputs 5 VDC, and that powers a PIC micro. I'm curious how is the Microchip's ZCD (Zero cross ...
2
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5answers
1k views

DIY zero-crossing circuit, how crucial are component values?

I want to build this circuit, taken from here, and I'm wondering exactly how crucial exact component values are. I don't have any 220k, 22k, or 4.7k resistors. I'm wondering if I can substitute two ...
2
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6answers
8k views

Confusion with TRIAC firing and zero crossing point

The reason for firing a TRIAC very close to the zero crossing point is explained as to avoid RF or EMI interference. Below is an excerpt from a book: What I'm having trouble to understand is that, if ...
2
votes
1answer
9k views

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 ...
2
votes
3answers
2k 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?
2
votes
3answers
532 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. I ...
2
votes
2answers
6k 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 ...
2
votes
1answer
3k 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: http://www.vishay.com/docs/83608/...
2
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1answer
131 views

Zero-crossing in AC with DC offset signal

Introduction I have a project about measuring the voltage, current and power factor of an electrical system. I had designed a system that allows the microcontroller to measure the peak of an AC with ...
2
votes
4answers
583 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 little ...
2
votes
1answer
713 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 'zero-...
2
votes
1answer
76 views

zero-crossing detection: to optocouple or not to optocouple?

That is the question. Most of the diagrams I have seen on the interwebs are of the opto-coupling school of thought: But the AVR182: Zero Cross Detector application note just throws in the resistors ...
1
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2answers
91 views

Zero crossing detector inconsistency

I designed the following zero crossing detector using an FOD819S optocoupler (U5): The source of the optocoupler is connected to a MB6F full-bridge rectifier (D2) which is supplied by a 9V ...
1
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1answer
509 views

Are these BLDC waveforms making any sense?

I'm trying to drive a BLDC with a microcontroller, a discrete inverter and a sensorless network for feedback. Here's the model I'm using and what ultimatly is my PCBA: I'm driving this thing open ...
1
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3answers
870 views

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 ...
1
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1answer
63 views

Core-less transformer for Zero-crossing detection

If possible, what are calculations and precautions involved in making a simple transformer without core? The only purpose of this transformer is to trigger an opto-coupler for zero-crossing detection ...
1
vote
1answer
213 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 ...
1
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1answer
44 views

Tapping into a 5.1V transformer for a zero-crossing detection circuit

I want to make myself a reflow oven following more or less this guide: http://andybrown.me.uk/2015/07/12/awreflow2/ Here is the zero-crossing detection circuit diagram: Thing is I would like to cut ...
1
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1answer
178 views

Mains AC TRIAC offset circuit

I'm designing a fluorescent lamp dimmer circuit which will work with Arduino pro mini. The mcu will detect zero cross from mains outlet and will give out offset for TRIAC. I would just like to get ...
1
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3answers
1k views

How to create a zero crossing detector using a full bridge wave rectified circuit

Currently 1) I have a full bridge wave rectified ac waveform of 10Vmax. 2) I also have a potentiometer adjustable DC waveform. 3) My rail voltages are +12V and -12V. 4) I currently supply my full ...
1
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1answer
256 views

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 ...
1
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1answer
323 views

How to account for input noise on a zero crossing detector op amp?

To save potential confusion let me start by saying I just started learning opamp theory about a week ago. I'm currently familiar with inverting, non-inverting, summer, and difference opamps. My (...
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1answer
82 views

A problem regarding connecting the grounds within two seperate circuits

Figure 1 I am trying to design the above circuit for my project to create zero crossing detector as shown in the above figure. This configuration was proposed originally by the member named "...
1
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1answer
194 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 ...
1
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1answer
1k 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 ...