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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49 views

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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34 views

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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1answer
164 views

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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1answer
53 views

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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1answer
23 views

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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4answers
766 views

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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1answer
84 views

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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1answer
67 views

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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3answers
186 views

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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46 views

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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1answer
60 views

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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2answers
204 views

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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2answers
61 views

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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4answers
952 views

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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1answer
80 views

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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3answers
124 views

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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0answers
49 views

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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1answer
120 views

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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111 views

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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1answer
98 views

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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1answer
203 views

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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3answers
2k views

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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3answers
330 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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1answer
268 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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2answers
941 views

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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291 views

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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2answers
314 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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183 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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2answers
135 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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1answer
184 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
65 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
61 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
109 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
613 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
308 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
721 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
326 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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3answers
1k 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
2k 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 ...
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1answer
275 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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118 views

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
3k views

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
444 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
1k 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
435 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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0answers
207 views

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
999 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
517 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
850 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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995 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 ...