Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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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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 with the microcontroller? I also need to detect…
m.Alin
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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 successful but is it advisable ? what other way…
iamgopal
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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 references or explain how you found out. Thank you!
Daniel Donnelly
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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, probably because I don't understand the datasheets…
Mark
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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 between low-to-high transitions using a…
TrivialCase
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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 Zero Crossing Detection. When the AC voltage crosses the zero, the Microcontroller will…
Mehrdad Kamelzadeh
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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 developing on an 8051-based SoC with RF circuitry…
Morten Jensen
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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 motor is an inductive load so the zero-crossing of…
m.Alin
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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 that the resistor needs to be quite large : CTR >…
Vorac
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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 resistor, and folks have suggested using…
Isaac Sutherland
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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 supply from Microchip's Application Note AN954: I'm…
BG100
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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 if I hook up my scope then I get the following…
ChThy
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Zero crossing detection and full-wave rectifier for non-AC voltage

Our control signal that ranges from -5 to 5 V needs to be split up such that the magnitude and sign can be send through different wires. So, for example, a -3 V input sends a 3 V signal through one wire, and a low signal through another, while a 3 V…
9sven6
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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 circuit : Circuit and Code Link Code which i…
Daniel Euchar
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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-crossing to control the heating element? I already…
Lukali
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