This is 8 Channel 5-12 V Solid State Relay Module. A solid-state relay (SSR) is just what it sounds like; an IC that acts like a mechanical relay. They allow you to control high-voltage DC  loads from lower voltage DC control circuitry. They accomplish this by using infrared light as the ‘contact,’ a solid-state relay is really just an IR LED and a photo Triac sealed up into a little box. Solid-state relays have several advantages over mechanical relays.

A Solid State Relay is similar to a mechanic relay where it can be controlled through a digital signal. Solid State Relay generates no noise and has a much longer lifespan compared to the traditional mechanic relay.

When the input logic voltage is applied to the coil, the NC will disconnect from the COM breaking the conductivity between the two. At the same time, the NO will connect with the COM allowing conductivity between them. Depending on your wiring this will turn on or off the connected load.

Features:

1. Control 8 loads of up to 5amps each at 12 - 24V DC.
2. Home and industrial Automation 
3. Has been assembled, and the electrical test passed.
4. Led indicator for each relay.
5. Use it to control various appliances and other equipment with a large current.
6. It can be controlled directly by a Microcontroller

Input Parts :

1. Input  Voltage Vcc - Gnd  connected to VCC (Supply power according to relay voltage)
2. DC-: connected to GNd
3. CH1: relay module signal trigger point (Effective low-level trigger)
4. CH2: relay module signal trigger point (Effective low-level trigger)
5. CH3: relay module signal trigger point (Effective low-level trigger)
6. CH4: relay module signal trigger point (Effective low-level trigger)
7. CH5: relay module signal trigger point (Effective low-level trigger)
8. CH6: relay module signal trigger point (Effective low-level trigger)
9. CH7: relay module signal trigger point (Effective low-level trigger)
10. CH8: relay module signal trigger point (Effective low-level trigger)