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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PWM signal generator circuit does not work in real life

I designed the motor soft start circuit in the figure below. I ran the circuit in simulation programs, but when I tried it on a breadboard in real life, I could not get a PWM signal. When I examined ...
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Fixing overshoot in current regulation of AC electronic load

My AC electronic load (previous question here) shall have a constant-current mode. It is being simulated in LTspice. @devnull helped design the circuit for AC loads, but for simplicity's sake in the ...
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How to guarantee clearance/creepage on mains side of an optocoupler used for 230VAC zero-crossing detection?

Update: Added a diode to protect optocoupler LED As stated in several safety standards (UL 60950 or UL 60750 for example,) we have to guarantee a minimum clearance/creepage between signals of opposite ...
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Zero-cross detector does not detect all the zeroes

I'm trying to do a zero-crossing detector but it is only able to mark half the number of zero passings. It seems to work fine with input voltages of 10-20V, but when using a +120VRMS it checks only on ...
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Suggestions to clarify comparator circuit

I'm confused with the next issue from school that I can't figure out and wasn't able to solve (this is homework already graded, but the teacher refused to explain me). I was asked to design and ...
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What are the disadvantages of using NZC Optocoupler as switch

I've bought some MOC3023 to use with a triac for turning some home appliance on/off using an EPS8266. The thing is.. every place that I search says that for on/off the best is a zero crossing detector ...
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Unexpected Crossover Distortion

I created and built the following circuit: When the SWITCH is closed, the audio amplifier works as expected, with no noticeable crossover distortion. When the SWITCH is open, the amplifier still ...
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Zero current detect circuit

I would like to make a primary side regulation (PSR) flyback converter, but I have one thing I do not understand. I read this document from ON Semi. If I want to do PSR, I need to detect the diode ...
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Unexpected voltage shift in zero-crossing detector circuit

I have designed following circuit of a zero-crossing detector, which is supposed to amplify small sine wave signal and convert it to (digital) square wave. It uses one single supply op amp for ...
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TRIAC phase angle control 120 VAC line ripple

I'm working on a phase angle controlled TRIAC dimming circuit (schematic attached below), and I'm seeing a lot of ripple/noise on the 120 VAC input as I near 50% power. I'm wondering what I can do in ...
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Does a signal that doesn't change polarity charge a capacitor?

I'm wondering if a digital signal that does not change polarity charges a capacitor. If the signal has a frequency of 1 MHz, does that charge the capacitor faster? And if so, is it possible to ...
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acs37800 zero-crossing signal timing problem

I'm working on a project that is using ACS37800 for measuring current and voltage and for detecting zero-crossing. However, there is some issues with the timing as the zero-crossing detection is off. ...
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Optocoupler 4N25 cut and saturation for zero crossing detector circuit

This is my first time working with an optocoupler and I'm trying to find the right resistors for a zero crossing detector circuit that has a 4N25 optocoupler, but the values I've calculated are not ...
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Resistors for zero crossing detector with optocoupler

I'm trying to understand how to calculate the right value for resistors R1 and R2 in this circuit using the 4N25 optocoupler, and with 12Vac. With 12Vac, Vp is 16.27v. In this case, the optocoupler ...
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AC zero Crossing detection with transformer

I am working on a circuit that requires zero crossing detection. I detected the zero crossings of the 230 Volt AC sine with the help of a full bridge rectifier and a 4N25 optocoupler with a pull up ...
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Detecting absence of current in transformer secondary

Beginner here. I'm trying to build a circuit which charges a capacitor to an arbitrary voltage in the shortest possible time. I want the high voltage part of the circuit to be galvanically isolated ...
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Zero current switching SMPS with common emitter or source

Is there any? Is it even possible that such arrangement could exist? Im interested in SMPS where both, turn ON and turn OFF processes of all switching elements happen at zero current through that ...
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Finding zero cross of AC signal digitally

I'm measuring 50/60 Hz with STM32 microcontroller. The signal comes from current transformer. I'm adding a DC shift to the signal equal to 1.65V. As the signal is riding in 1.65V, this will be my zero ...
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Generating a cross zero pulse wave

For a project I need a zero crossing wave like this Its generated by an inductive coil of a distributor of a car engine where that signal triggers a CDI (capacity discharge ignition) when it falls ...
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Switching Relay at Zero_Cross Point

I'm controlling 4 Relays(10A) with a controller. While randomly switching it without zero-cross my controller gets restart. To avoid this I'm switching relays at the zero-cross point, But my question ...
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3 answers
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Zero Crossing Detector Circuit

I am working on a zero crossing detector circuit. Can anyone please explain the function of highlighted circuit?
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Zero cross control for inductive loads

Is zero cross control acceptable for small motors? I know it is bad to have voltage and current out of phase for inductive loads but wanted to know if it would not be harmful to small motors (< 500 ...
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Doubt about zero-cross circuit

I have simulated the following circuit on MultiSim, and it seems to work well doing its job. The first element is a full wave bridge rectifier. At its output is connected the input of the zero-cross ...
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2 answers
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Using a behavioral voltage source as a zero crossing detector for inductance current in LTSpice

I'm trying to simulate a buck converter IC in LTSpice (MP4569) based on the functional block diagram from the datasheet using behavioral voltage sources to represent the logic from the block diagram. ...
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Zero crossing circuit

I have made a simlpe zero crossing circuit to control the speef of a single phase AC fan through conduction angle control with a Triac. The circuit looks like this with the use of 4n25, an optocoupler:...
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Tachometer IC that does not require zero-crossings?

I recently built the basic tachometer circuit in this LM2917/LM2907 Datasheet shown below using the 8-Pin version of the device. I realize this circuit requires a VR pickup sensor, and so the LM2907/...
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Zero Crossing Detector using comparator

I followed SNOA999 for a zero crossing detector using TLV7011 as a comparator. I am not sure about short-circuiting grounds between AC and DC power sources. My concern is creating negative currents on ...
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3 answers
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Zero cross detector output

I have realized what I thought was a classic zero cross detector circuit using an H11AA1 chip: https://www.digikey.com/product-detail/en/on-semiconductor/H11AA1SR2M/H11AA1SR2MCT-ND/2094174 My circuit ...
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Need help in zero cross circuit by using op-amp

I worked on zero crossing circuit by using opto-coupler.Circuit is It is working okay.Zero_crossing signal is There is a 2-3 ms of signal loss is happening with 50Hz of AC signal.I don't want more ...
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Undesired noise on isolated zero-cross

I have a prototype board which I'm currently testing the signals of its zero-cross circuit. This is the schematic of the PSU, the power supplies of the low voltage part of my circuit (12V, 5V, 3V3) ...
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LM741 Cross-Over distortion

Could anyone explain why I may see cross-over distortion in my output signal of this op-amp circuit? The input is a 1Vpp sine wave at a frequency of 10kHz, with no DC offset. I am definitely seeing ...
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Momentary overloading of a mains transformer at low duty cycle operation - what could go wrong?

I'm planning on using a 120 VA Hammond 1182P12 toroidal transformer to deliver 24 VAC to a 2.5 Ω resistive load (a JBC C245 soldering iron cartridge), implying 9.6 A RMS, 230 W if continously applied. ...
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Need help to design efficient zero crossing CURRENT detector : clamp diode solution

I try to design a replacement potter's wheel motor controller for an old potter wheel. I have solve my zero crossing voltage detector and TRIAC command. Now I begin to understand the importance of the ...
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11 votes
3 answers
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Very high precision zero crossing detection

I have a setup that is equivalent to a guitar string with pickup, with signals of similar frequency range. I have a simple zero crossing detector with a comparator and then just count the interval ...
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1 vote
3 answers
537 views

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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2 votes
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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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2 votes
2 answers
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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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1 vote
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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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2 votes
2 answers
425 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 ...
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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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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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2 votes
1 answer
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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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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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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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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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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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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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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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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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5 votes
3 answers
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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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