???Relay Switch Module???5pcs 1-channel photocoupler isolator with stable performance, triggered by DC 12V and 1mA current. ???Signal Voltage???Positive phase amplification with high-level trigger. Output equals input. ???Level Converter???Opto-isolators can be used as level converters (NPN-PNP, PNP-NPN), signal input to MCU in isolation, or MCU-controlled device output in isolation. ???Control Transformer???Optocoupler isolation board provide isolation between low and high-voltage circuits when used with other electronic devices. ???Functional Application???Devices for microprocessor Input/Output switching, DC/AC power control, communications equipment protection, and power supply regulation.