2-Channel PC817 Optocoupler Isolation Module - Voltage Converter & Signal Isolator

Specifications

• Channels: 2 Independent Channels

• Isolation Chip: Sharp PC817 (SMD)

• Input Signal Voltage: ~3.6V to 24V DC

• Output Voltage Range: ~3.6V to 30V DC

• Maximum Output Current: ~10mA to 15mA (Intended for signals, not driving heavy loads directly)

• Maximum Switching Frequency: ~4 kHz (Practical limit for PC817)

• Dimensions: 38.0mm x 29.2mm

• Connection Interface: Screw Terminal Blocks

Key Applications and Projects

• Industrial PLC Interfacing: Allowing fragile 5V hobbyist microcontrollers to communicate safely with 24V industrial Programmable Logic Controllers.

• Motor Noise Isolation: Separating the noisy, spike-heavy power rails of high-current DC motors from the clean power rails of your sensors and logic boards.

• Ground Loop Elimination: Breaking the physical ground connection between two separate audio or data systems to prevent humming and ground loop interference.

Unlock New Capabilities (Project Evolution) The Smart Factory CNC Upgrade: Are you retrofitting an old, heavy-duty CNC milling machine with a modern 32-bit controller? Old stepper drivers often operate on 24V logic and produce massive electrical noise. Evolve your retrofit! Place this 2-Channel Optocoupler module between your new 3.3V control board's Step/Direction pins and the old motor driver. You will simultaneously step up your 3.3V logic signals to the required 24V, while completely isolating your delicate new motherboard from the archaic, noisy power grid of the mill!

Package Includes:

• 1 x 2-Channel PC817 Optocoupler Isolation Module

• 2 x Yellow Configuration Jumpers (Pre-installed)

FREQUENTLY ASKED QUESTIONS (FAQ)

1. What exactly does this optocoupler module do? This module acts as an electrical firewall. It uses light to transfer a signal from one circuit to another without any physical wire connection, protecting delicate microcontrollers from high-voltage spikes and allowing you to convert logic voltages (e.g., translating a 3.3V signal to a 24V signal).

2. How does optical isolation work inside the PC817 chip? Inside the tiny PC817 chip, there is an infrared LED facing a light-sensitive phototransistor. When voltage is applied to the input, the LED turns on. The phototransistor sees the light and completes the output circuit. Because there is a physical gap between the LED and the transistor, electrical noise cannot cross over.

3. Why do I need optical isolation in my project? When controlling heavy inductive loads like DC motors, solenoids, or large mechanical relays, they can generate massive "back-EMF" voltage spikes. Without isolation, these spikes can travel back through your wires and permanently destroy your Arduino or Raspberry Pi.

4. Is this board bidirectional? Can signals flow from the output back to the input? No. Optocouplers are strictly unidirectional. The signal can only flow from the input terminal block to the output terminal block. Light cannot travel backwards through the chip.

5. Does this module work with 3.3V logic devices like Raspberry Pi or ESP32? Yes! A 3.3V HIGH signal is more than enough to trigger the internal LED and activate the optocoupler's output.

6. What is the maximum input voltage I can safely apply? The input circuit features onboard current-limiting resistors, allowing it to safely accept signal voltages anywhere from roughly 3.6V up to 24V DC without blowing out the internal LED.

7. What is the maximum output voltage range it can handle? The output side (phototransistor) is rated to handle switching voltages from approximately 3.6V up to 30V DC.

8. Can I use this module with AC (Alternating Current) voltage? No. The PC817 optocoupler and this specific module design are strictly for DC (Direct Current) circuits only. Applying AC voltage will damage the module.

9. Can I use this to drive a heavy DC motor directly? No. The PC817 phototransistor can only handle a tiny amount of current (typically around 10mA to 15mA). It is designed to switch signals, not raw power. To drive a motor, use this module to send a clean signal to a heavy-duty MOSFET or relay module.

10. How much current does the input side draw from my microcontroller pin? It draws very little current—typically between 2mA to 5mA depending on your input voltage. It is essentially the same as powering a standard small indicator LED, making it perfectly safe for fragile logic pins.

11. Should I connect the Input Ground and Output Ground together? Absolutely not. Tying the input ground to the output ground completely defeats the purpose of optical isolation. You must maintain two completely separate power supplies and isolated grounds to ensure your microcontroller is protected.

12. What do the IN1/IN2 and V1/V2 labels mean on the terminal blocks? IN1 and IN2 are the signal inputs for Channel 1 and Channel 2 (connect these to your Arduino). V1 and V2 are the corresponding isolated outputs (connect these to your 12V/24V PLC or relay).

13. Do I need to solder wires to this module? No soldering is required. The module features heavy-duty screw terminal blocks. Simply strip the ends of your jumper wires, insert them into the green blocks, and tighten the screws with a small flathead screwdriver.

14. What do the two yellow jumpers on the board do? The yellow jumpers configure the output side to be "pulled high" or "pulled low." Depending on how you orient them, the output can default to a HIGH voltage state and pull LOW when triggered, or default LOW and pull HIGH when triggered.

15. Does the module invert the logic signal? It can, depending on how you configure the yellow jumpers and wire your output load. You can easily set it up to act as non-inverting (HIGH in = HIGH out) or inverting (HIGH in = LOW out).

16. Can I use this for high-speed signals like I2C, SPI, or fast PWM? No. The PC817 is a relatively slow optocoupler. It works perfectly for basic on/off switching and low-frequency PWM (up to roughly 3 kHz to 4 kHz). For high-speed data, the phototransistor cannot turn on and off fast enough, and the signal will blur.

17. What is the maximum switching frequency? The practical switching limit for the PC817 chip on this module is around 4 kHz.

18. Can I use this to trigger a 5V solid-state relay (SSR)? Yes, this is an excellent use case. The optocoupler can send a perfectly clean 5V signal to the SSR, ensuring that no AC mains noise leaks from the SSR back into your 3.3V or 5V logic board.

19. What are the physical dimensions of the board? The printed circuit board is highly compact, measuring exactly 38mm in length and 29.2mm in width.

20. Why is my output not triggering even though my input is connected? Check three things:

1. Ensure you have not accidentally swapped the input polarity (positive and ground).

2. Ensure the output side actually has a secondary voltage supply connected to it (the output side does not generate voltage; it only switches the voltage you provide it).

3. Double-check that your input and output grounds are separated but correctly wired to their respective independent power supplies.