0
votes
2answers
151 views

Debugging a garage door opener circuit with an optocoupler and mosfet

There seem to be many related questions, but I can't quite find the answer I'm looking for. I've got a garage door opener switch. There's 16V across the wires, and when you short them, the garage ...
0
votes
3answers
130 views

High frequency mains sensing

I want to sense mains voltage at a frequency faster than 5000Hz, with a microcontroller. The idea behind this is to visualize the actual shape of the AC voltage, and eventually to compare it with the ...
2
votes
2answers
126 views

Filter 5v pulse from micro input

I am monitoring an external system which sends out a 5v pulse every 2 seconds when in normal mode. When the motor is working, it sends out a constant 5v designed to power a flashing light or LEDs as a ...
0
votes
0answers
36 views

PCB design with 230VAC and 5VDC [duplicate]

I've developed a small circuit that aims to dim a lamp. Iit works fine on my breadboard, so now I'm building my own PCB. I never built a PCB with 230VAC on it and controlled by a 5V microcontroller. ...
0
votes
0answers
77 views

Optoisolation with make or break pneumatic contacts

The design I've been working on is based on the previous generation of the circuit that my customer has been using for many years. There are several pneumatic make or break switches that are triggered ...
4
votes
6answers
304 views

Does opto-isolation matter when there's only one power supply?

Optoisolators are often encouraged for isolating signals controlling higher voltage loads. The typical example is a low-voltage microcontroller controlling a motor or solenoid operating at a higher ...
2
votes
0answers
313 views

Using optoisolator and triac with mcu to switch light on/off--need low power alternative

I'm using the schematic below to control a lamp (light bulb) with a microcontroller and I'm running the mcu (and moc3010) off of AA batteries. I just realized the moc3010 has an LED in it that needs ...
2
votes
1answer
551 views

why does the microcontroller pin driving optocoupler is giving 2V even if it is set?

I have interfaced pin 1^1 of Atmel AT89S51 to optocoupler MOC3041 IC, I set this pin to logic high. I have connected 220 ohm resistor and red led and then pin 1 of the optocoupler and after that ...
2
votes
1answer
385 views

Controlling multiple triacs with microcontroller for light dimming: where to use optoisolators

I want to control (dim) multiple mains lights using triacs and a microcontroller. (One triac per light). I want to keep both the costs and component count as low as possible. Is it necessary to have ...
2
votes
1answer
612 views

Optocoupler with 220V DC

i need help from you. I want to use 220V DC input to microcontroller. For this purpose i have to use optocoupler, so how can i choose optocoupler with input for 220V DC? Thanks!
2
votes
1answer
1k views

how to put led to indicate the signal is functioning

I want to connect an input signal to pc817 and the output to a microcontroller. I don't know how to put the LED at the input to indicate that the input signal is working. For example my input is ...
6
votes
2answers
3k views

driving a relay with transistor and Opto-isolator

I am very new in electronics. I am controlling a relay with stm32 micro controller. For the isolation I have used a 4N33 opto-isolator. As my relay coil needs around 250 mA, I used a mps222 ...
17
votes
4answers
1k views

Why are relays so frequently driven by optocouplers?

Since the advent of the many microcontroller development boards, like Arduino, there have been a number of relay modules sold to drive mains AC loads. A lot of these seem to use an optocoupler, ...
4
votes
1answer
219 views

Multiples voltage on a optoisolated MCU input problem

The problem Handle digital inputs on a MCU, the input could be 5V, 12V, 24V or an open collector. My solution My approach is based on jumpers, given the fact that the inputs dont change behavior in ...
1
vote
1answer
305 views

Alternative to optocoupler? Other switching devices?

I have a part that classifies what kind of power I get on ethernet by presenting different loads. For example, the part needs to have a 100 Ohm resistor across two of its pins, and the part will ...
11
votes
2answers
4k views

opto isolated arduino input

I want to protect a pin with an opto isolator to get an external signal from an electrical meter (35VDC max, 50mA max, 240ms pulse width). The purpose is to count the pulses. Do you have some ...
9
votes
4answers
13k 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 ...
2
votes
1answer
845 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. ...
1
vote
2answers
251 views

Connect a microcontroller to a gadget

Although I have average programming skills, I'm not far from being an noob concerning electronics! I therefore want to kindly ask you to help me connect my (already programmed) Arduino Uno to the ...
7
votes
3answers
7k views

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 ...
1
vote
1answer
620 views

Is this galvanic isolation?

I'm doing a project which consists of 2 big parts: a control part (a microcontroller with I/O pins expanded, USART-to-USB, a RTC, an EEPROM, a LCD) working @ 5V and an actuators part (optocouplers for ...
8
votes
3answers
18k views

How to drive a MOSFET with an optocoupler?

What's the proper schematic for driving this MOSFET from a microcontroller pin through this or this optocoupler? The MOSFET will drive a motor @ 24V, 6A.