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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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Audiable pops when switching DC biased audio signal

In my previous question, I have asked how to DC bias audio signal for a crosspoint audio switching matrix (Switch array (crosspoint) and DC biasing of audio signal). I am using the following circuit ...
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59 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 ...
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HCPL3700 - 220V sensing circuit

I want to use HCPL3700 optocoupler for sensing 220V (line). I design a circuit but I want to ask some questions. HCPL3700 is an open-collector output so I pull-up Vout. In AC voltage sensing some ...
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Controling a Washing Machine AC Motor Using a Relay

I would like to control the motor of my washing machine using an Arduino. It's an old washing machine with a mechanical controller and an AC motor connected to a 12.5 uF run/start capacitor. According ...
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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 ...
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49 views

ZCD with PIC 18LF45K40

I want to implement phase angle control for a single phase ac fan. To achieve that we need a ZCD circuit interfaced with a microcontroller to get a pulse at zero crossing. As our circuit has some ...
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1answer
38 views

Zero Crossing Signal Timing

I have a zero crossing circuit for dimming lamps exactly like the below According to my calculations: \$ I_{R7} = \frac {V}{R} = \frac {3.3}{10k} = 0.33~mA\$. Considering TCMT1109 transfer ratio ...
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72 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 ...
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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 ...
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1answer
40 views

Static VAr Compensation

I have to design a 3 phase Reactive Power Compensation System with using only reactors, no capacitor is needed. Total capacity is 505kVAr, but 475kVAr will be done with contactors, rest (30kVAr) will ...
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1answer
67 views

Best TRIAC for zero cross detection

I already asked this question Triac BT 136 getting shorted when load is given to T1. When I referred this link, I understood rate effect is the root cause for our problem. To avoid this either we ...
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2answers
227 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 ...
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1answer
118 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 ...
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1answer
300 views

Arduino PID and AC controlling

I'm trying to make my own PID temperature controller using Arduino. Arduino PID library outputs a PWM signal. I need to control 230VAC using this PWM like a triac phase angle controlling. If I use a ...
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1answer
245 views

Zero-crossing signal inconsistent timing

I have an ESP-07 with NodeMCU firmware connected to a dimming module with a zero-crossing pin. The current frequency should be 50Hz, which means that the time between two zero crossing should be 10ms,...
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871 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-...
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3answers
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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 ...
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1answer
172 views

direct ac mains to MCU pin for zero crossing detection

to detect Zero Crossing of ac mains, can i connect an EFM8 pin configured as input directly to 220V ac via a resistor?
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What's the best way to detect zero crossing in this design?

The design that I am talking about: I want to be able to detect the zero point with an MCU of which pin can withstand only 3.3 V. I'll forgo optocoupler because A. I want everything to be as cheap as ...
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1answer
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Counting the number of zero crossing using arduino uno

will this code work to display the frequency of input signal of zero crossing detector? ...
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1answer
220 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 ...
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4answers
499 views

Zero Crossing Detection of ~ 400 kHz Signal with MCU

I want to measure the frequency of a signal using the digital input pins of the NUCLEO-F767ZI. The signal is sinusoidal with an amplitude of 5 V and a frequency ranging from 100 kHz to around 400 kHz. ...
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2answers
251 views

Can triac opto-coupler used as a simple optocoupler?

I had more than 50 pcs of MO3041 but in my circuit need operation like 817. I know i can use 817 for DC circuit but i am just want to know if i can use MO3041 in DC circuit. I know there is a simple ...
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Swap main terminals of zero-crossing triac

The question I have is maybe silly, but I cannot find strictly related info. When designing a mains switch with an optotriac driven triac (or discrete SSR for you), during layout I swapped the ...
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1answer
479 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 ...
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1answer
319 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
540 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 ...
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1answer
480 views

Zero cross circuit exploded

would like to get a feedback on a zero cross circuit as it does not work. Circuit is based on this. 240V AC, 50 Hz Expect that C2 is 50V. R1,R2, R4 are SMD. After connecting to mains and measuring ...
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1answer
170 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 ...
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1answer
524 views

Current zero cross detection circuit off of triac

I need help modifying the circuit below. The assumption in this circuit as it stands is that AC Hot would be common to GND and then MT2 of the triac would go through a light source to AC Neutral. ...
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1answer
78 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 "...
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4answers
598 views

Linear power supply + zero-crossing detection on transformer secondary

Having read this comment, I'm a bit concerned about whether one of my projects is going to work: simulate this circuit – Schematic created using CircuitLab The comparator is also inside the uC,...
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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 ...
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how to construct zero cross detecting circuit for line current? [closed]

I am constructing Optocoupler based Zero cross detection circuit for power factor correction.How to find zero crossing of current wave?please recommend the circuits with resistor calculations. ...
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602 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 ...
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5k views

Zero crossing detection and Light dimmer

I am confused by zero crossing detection of opto-triac. I know what is the zero crossing detection or switch. (ZCS) Zero crossing detects what is the point that wave is going to positive to negative ...
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199 views

Zero Cross TRIAC circuit for regulator fails on voltage spike

I am using a ZC TRIAC circuit to switch and regulate an electric appliance e.g. a table fan, a electric drill etc. I must confirm that proper SNUBBER circuit is used and everything works fine. I ...
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994 views

ZCD with LM358 not working

I've made this circuit to detect de zero cross but in out pin (pin 7) the voltage are about 3,7V fix. I've already measured pins 5 and 6 and the delta voltage ( vin+ and vin-) are inverting. I had ...
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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 ...
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4answers
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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 ...
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What is the best detection strategy for FSK and PSK demodulator

I am Modulating the bits using FSK and PSK modulators and sending them to the demodulator and the demodulator is using simple zero crossing detection to detect the bits. But the problem is, when I ...
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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 ...
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1answer
392 views

Problem in AC fan speed control(using ZCD and Atmega8A) when running on Inverter

I recently built an AC fan speed control circuit using Atmega8a,Triac,2 nos Optocoupler and ZCD method.I am attaching the necessary circuit regarding the triac firing and ZCD.The Atmega is configured ...
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2answers
1k views

Zero Crossing Circuit Input Resistor

I'm building a dimmer, and got some questions about the resistor in the zero cross circuit. My circuit is like the image above, and I'm wondering if in the case of 100V input the current is to small. ...
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2answers
1k views

Triac drivers with or without zero-crossing detection

I've been looking at this schematic for triac control by varying the gate pulse timing. The description states that the triac switches off automatically at zero crossing and when there is no gate ...
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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 ...
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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 ...
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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 ...
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1answer
253 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 ...
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3answers
847 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 ...