An optoelectronic device which combines an optical transmitter and receiver in a single package; commonly used in galvanic-isolated control applications such as power supplies.
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1answer
121 views
Efficiently driving 8 low-current Optocouplers
I'm looking to drive a bank of eight FOD4216 random phase triac drivers. I'm looking specifically at the (insanely expensive, $3!) Fairchild FOD4218, which needs 1.3mA to switch. 8 * 1.3 = 10.4 mA ...
2
votes
1answer
108 views
VO2223A datasheet query — pin 5
This is a follow-up to a previous question, regarding the VO2223A opto-coupler/Phototriac. My understanding of the chip is that the IR LED triggers a phototriac, which in turn drives the gate of a ...
0
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2answers
341 views
i2c bus isolation using Si8400
I am currently working on optical isolation of the i2c bus in order to remove the risk of damaging the PI from outside noise.
I am using Si8400 optical isolator but I was so far unable to make it ...
0
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0answers
42 views
Using TLP280-4 with STM32F1xx MCU
This is a continuation of my previous question.
Olin Lathrop explicitly explained me the previous question, but also set thinking on the exact way of connection the optocoupler to a MCU input.
I ...
1
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2answers
70 views
How to use electrically isolated weak signal for Arduino interrupt?
I'm trying to use the signal generator from a DSO Nano v2 to drive an Arduino interrupt for testing purposes. I have measured the output of the signal generator at approximately 13mA @ 2V DC.
I have ...
0
votes
1answer
84 views
TLP280-4 Optocoupler on 12/24V inputs
There is a STM32 device which has to detect several signals from other devices. The voltage of these signals can be 12V or 24V. Also these signals can be positive (i.e. 12/24V) or negative (connected ...
1
vote
1answer
69 views
connection from an comparator to an optocoupler
I have the circuit below to decode a signal that is defined as Logic high >9.5 V and Logic low <6 V
To determine the ...
1
vote
2answers
63 views
how many resistance do i need to safe the LED of PC814?
if i have a input of 5v (arduino HIGH) on the LED of a PC814, how is the value of the resistance that i must use before that, so i don't burn the led?
...
0
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1answer
119 views
Optoisolator always on on the high-voltage side
I am building a simplified version of this circuit:
As far as I can tell, it is a pretty standard design. The load will be a dumb resistive heater (this is a sous vide project).
For now, the ...
6
votes
2answers
427 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 ...
3
votes
1answer
178 views
Criteria behind selecting pwm frequency for speed control of a dc motor?
I'm working on a speed control circuit for a brushed dc motor (24v, 500rpm, 2A, 4kgcm).
The main components that I plan to use are PIC16f873, 4n25 optocoupler, IRFZ44N MOSFET, BY 500 - 800 diode(for ...
6
votes
4answers
370 views
Validate Triac circuit
I'm designing a device to switch a heating device driven by mains power. I've done quite a lot of research and realize there's a lot of information out there but as i'm dealing with potentially deadly ...
0
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1answer
231 views
How do I select an optoisolator to both provide zero crossing to a uC and controll a triac?
This application note states that zero crossing detection can be achieved in an AVR with just a couple of resistors. However, it forgoes galvanic isolation and this is not acceptable for me.
I would ...
2
votes
2answers
304 views
Isolated MOSFET output stage calculations
I am a newcomer in this wonderful world of electronics trying to design my own PLC.
So far I have designed a single output stage that I think will work, but it would be great if i could have any of ...
1
vote
1answer
107 views
How to switch between a solar panel and battery?
A 12v battery is being charged from a solar panel. When battery is 12v solar panel is disconnected from battery and connect the load with battery. And again solar panel is connected with battery when ...
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votes
6answers
408 views
Optoisolate two ICs sharing same power supply
I have two ICs. The former acts like an ADC, measuring the voltage in a power outlet and transmitting the result to the last. Both ICs requires 5 Volts to work.
I ...
3
votes
1answer
64 views
Why is there a minimum Ic for a optocoupler?
I got confused when I saw this on a HCPL-181 optocoupler datasheet.
You can get the datasheet here: HCPL-181 datasheet.
So what would happen if the collector current goes below 2.5mA? (In fact I ...
2
votes
2answers
116 views
How to de-couple DMX512 with opto-isolators?
I'd like to build a DMX512 device.
The problem I have is how to decouple the device from the bus. I decided to use opto-isolators, but how should I wire the diode part of the isolator?
Since I need ...
5
votes
1answer
134 views
How to connect RS232 (“Opto-RS232”)
--Background--
I'm setting up a pretty standard RS232 interface from a digital caliper to a microcontroller, via a MAX232 chip (or in my case, MAX3222, which is the 3.3V-supply variant with 2 ...
2
votes
1answer
177 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 ...
0
votes
1answer
101 views
How to implement a delay OPTOcoupler input there by the circuit remain on for the next 1 second
I have another new project , the project is simple one when a call lands to the mobile an ac machine is triggered and it turns off when the mobile ring stop , for that i have used this circuit
The ...
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1answer
83 views
What is “Saturated CTR” of an optocoupler?
For example, in the datasheet of 4n27: .
So what is saturated and what is non-saturated CTR?
5
votes
3answers
252 views
An opto-coupler/triac oddity — is it a problem, and is there a solution?
I'm using VO2223A opto-coupler/phototriacs to drive some low-current mains lighting with a PIC controller. All are working fine, but when the (DPST) mains switch is first turned on during system ...
4
votes
1answer
172 views
how to design a switch which works when an input of 0.10 is applied
i have an alarm clock , it's output voltage to the alarm buzzer is around 0.15 volt ,
i need to attach an electrical appliance to make it operate on scheduled time ,
for that i had used this circuit ...
14
votes
4answers
505 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
3answers
1k views
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 ...
4
votes
1answer
382 views
Arduino Uno with 12V pump: transistor or optocoupler+12V relay?
I'm not a real expert in electronics but I'm going to start a new project that has completely captured me.
I need to drive a 12V pump with my Arduino Uno. The pump is "Dp0102" (12V, 0.7A). To power ...
0
votes
0answers
97 views
Controlling USB Power with External Voltage Source
I was trying to figure out a way to add a switch to the USB +5V wire, that could be controlled with another voltage source. I was thinking about using an optocoupler + mosfet to do it.
More ...
4
votes
1answer
365 views
Optotriac+triac: how do I calculate the gate resistor
I am building a small circuit to turn on/off a 200W heater. I am using a MOC3023 and a BT136. At the datasheet of the the optotriac, this circuit is recommended:
My question is how is the 180Ohm ...
5
votes
1answer
191 views
Using the VO2223A to switch a 230Vac LED lamp
I'm looking for something that can switch on and off a 230 Vac, 26mA LED lamp, under microcontroller control. Would a VO2223A, driven by (say) a PIC or Arduino, work as a low-current SSR? The load ...
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0answers
181 views
Ring detector circuit, transistors not fully activating
I am attempting to build a ringer interface circuit, and I’m running into problems that are over my head.
The purpose of the circuit is to buffer the output of a central telephone system that goes to ...
4
votes
1answer
123 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 ...
5
votes
3answers
250 views
Can LEDs or optocouplers be used without a resistor if PWM is used?
LEDs are often connected through a resistor and the purpose of this seems to be to lower the voltage across the LED to around 1.8V. Can PWM be used to lower the voltage instead of a resistor? If so, ...
1
vote
1answer
2k views
How to use a phototriac coupler to trigger the main triac?
I have in my box of parts a phototriac coupler, namely a Sharp PC3SD21NTZ (datasheet), which is a zero cross type. I don't know how to use it, but I've been meaning to learn for a while.
This part is ...
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1answer
180 views
Why do they add a TRIAC after an MCP3020 optocoupler?
I have a relay circuit (I use it instead of a relay) that uses a MCP3020, which I think does the physical separation of the two circuits (it's a LED and a photo cell inside a chip) and a BTA08 TRIAC.
...
4
votes
1answer
399 views
AC detection for microcontroller
I need to monitor the state of multiple relays carrying 110VAC and 60VAC using a microcontroller (I will probably use an Arduino) to ensure the relays are working properly.
To do this I have figured ...
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votes
1answer
86 views
Controling Digital I/O [closed]
I need to turn on an 12 V or 24 V equipment with an digital Output. What is the best way?
I already tried out with a optocoupler, but nothing happened.
I need the cheapest solution.
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1answer
185 views
Calculating max wattage load for opto-triac
Are there any guidelines?
Do the guidelines differ depending on resistive/inductive/reactive loads?
For example, the Vishay VO2223A is rated up to 1A. At 110V it seems it can switch up to a 1 A x ...
0
votes
3answers
252 views
Fast opto-isolation with open collector output without VCC
I have a two wire communication channel, with a data line and a ground line, with the data line being pulled high via a resistor on the receiving end. I am supposed to send information on this line by ...
1
vote
4answers
625 views
Did I use this optocoupler correctly?
I'm planning on using this optocoupler in a PCB I'm making. I've never used one before so I want to make sure I'm doing this correctly and got the right numbers off the data sheet.
The image below ...
0
votes
1answer
119 views
Triac datasheet values
I have a Triac that I want to use to control low voltage (~16 V) AC. The data sheet is found here. It specifies that the peak gate voltage is 5 V with a peak current rating of 2 A (which seems quite ...
4
votes
2answers
491 views
Optocoupler with phototransistor base lead
I'm thinking about using 4N25 optocoupler - it has a separate lead for base of phototransistor. How do I use it? I suppose I can't leave it floating?
1
vote
2answers
516 views
How could I create two separate ground areas with Proteus?
I need to design a PCB layout to a system using an isolated communication with optocouplers, what means that I need separated ground areas, each one on one side of the communication that I want to ...
0
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0answers
32 views
opto without specs [closed]
I have an opto IC with lenses (lenses are tiny plastic dimples on IC) on a shaft encoder, but no identifying numbers can be read on the part. I determined the LED using a DMM to read 1.6V and it ...
3
votes
2answers
728 views
Is a protection diode needed on a TRIAC optocoupler and what for?
Please refer to page nine of the Sharp S108T01 / S108T02 datasheet:
Is this diode needed - why/why not?
How do I choose the correct diode, if yes?
UPDATE: Thank you all for your educational ...
1
vote
1answer
224 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 ...
0
votes
2answers
560 views
What does 'random phase' means in a triac driver?
I'm using this triac driver to control a triac. In its datasheet it says 'provide random phase control of high current triacs [...]'. What does that mean? It doesn't have zero-crossing detection?
1
vote
1answer
854 views
How do I choose my optocoupler?
I need to drive a solenoid with a MOSFET. And this command have to be isolated with an optocoupler but I don't know how to choose it. What characteristics do I need to watch in the datasheet? What is ...
6
votes
4answers
522 views
Optoisolate 2MHz SPI communication
I need to isolate the SPI communication between two chips.
The bottleneck of the communication is on the slave, which apparently can handle up to 2MHz SPI clock ...
1
vote
3answers
544 views
I2C optocoupler separation - which IC?
I am designing a circuit which will have some external I2C sensors connected to it and thus I want to protect it from noise - via an optocoupler. I have to say that I am a complete novice to this all ...
