4N25 4N25M DIP-6 Optoisolator Transistor

Description

Tutorial: How to Use 4N25

The 4N25 is an optoisolator used to protect electronic circuits from electrical interference. Useful for beginners and intermediates in electronics.

What you need

• Test Lead
• 1 kΩ Resistor
• Arduino
• LED

Steps

1. Step 1: Connect the 4N25 to the Arduino. VCC to 5V, GND to GND, OUT to pin D8.
2. Step 2: Connect the resistor to the LED. One end of the LED to the OUT of the 4N25, the other to GND.
3. Step 3: Upload the following code to the Arduino.
4. Step 4: Turn on the LED with a square wave signal.
5. Step 5: Check the maximum current on the datasheet.
6. Step 6: Try reversing the VCC and GND connectors.
7. Step 7: Check the behavior of the LED when the signal is low.
8. Step 8: Try connecting another component to the 4N25.

Example code

void loop() {  digitalWrite(8, HIGH);  delay(1000);  digitalWrite(8, LOW);  delay(1000);}

Mini project

Create a simple optical switch that turns an LED on and off.

Common mistakes

• Connect GND to VCC.
• Use a resistor that is too low for the LED.
• Ignore the maximum current of the 4N25.
• Do not check the LED behavior with low signals.

Recommended accessories

• LED
• 1 kΩ resistor
• Arduino
• Test lead

Frequently asked questions

What is the difference between 4N25 and 4N25M?
There is no substantial difference. Check the datasheet for specific specifications.

Can I use a different power supply than 5V?
Check the datasheet for compatibility with other voltages.

How much current can the 4N25 protect against?
Check the datasheet for the maximum current.