Linked Questions

4
votes
1answer
4k views

how to calculate resistor value for optocoupler - 230V [duplicate]

I am trying to implement the following circuit. I am trying to understand how the resistance values are calculated. I followed this - "how do I calculate resistor value" According to my optocoupler (...
31
votes
3answers
15k 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 ...
11
votes
4answers
37k 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 ...
7
votes
8answers
12k views

What is the easiest way to monitor a 120v line via software?

I'm wanting to count how often a water pump turns on, how long it's on for and when it turns off for an extended period of time. My plan was just to monitor the pressure switch, which is at 120v on 1 ...
6
votes
4answers
11k 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 ...
7
votes
2answers
2k views

connecting devices with two different power supplies

I wanted to know if this configuration is fine with two different grounds. the microcontroller is powered up with 3.3V and the transistor is powered by 5V. Both grounds are separate. My question is ...
4
votes
4answers
14k views

Optocoupler/relay type for isolating two DC circuits

I have recently started experimenting with an Arduino and would like to control a seperate circuit (for example, a small and cheap digital video camera powered by battery) from my arduino. Basically ...
8
votes
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 ...
5
votes
1answer
3k views

how to interface HCPL-3700 optocoupler to an input pin of ATmega16L

I want to detect logic of the mains supply (230VAC, 50Hz) and feed the output of HCPL-3700 into ATmega16L. I read through the datasheet but could not understand how to calculate the resistor values. ...
3
votes
4answers
723 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 ...
1
vote
3answers
169 views

Sensing 240V and converting to CMOS logic levels

I lab tested the circuit below, which Olin Lathrop designed in this answer. The problem is, on OUT (pin 4) of the optocoupler I get 1.7 volts when 240 V is applied to the high voltage (HV) side of ...
1
vote
2answers
209 views

What is optocoupler and how it is used? [closed]

Im curious about optocoupler. What is optocoupler,why and how it is used in electronic circuits ?
2
votes
1answer
126 views

How to isolate a zero-cross detector from phase-controlled simistor?

To control the average voltage, output by a triac, the controller needs to know the time of the zero crossing. But the circuit for detecting the zero-crossing is a sensor, vulnerable to noise; taking ...
-1
votes
1answer
74 views

240VAC signal to a 12VDC circuit

I have two light bulbs that one of them can be turned on and off from a switch. I want the other light bulb to be turned on when the first one turns on by the switch and stays on while the first one ...