8-Channel Signal Relay Modulebrand: SainSmart SKU: 101-70-114
- 8 Signal relay
- Interface definition:
- IN(x): High level. Low level cut-off
- This item has been assembled,
- Led indicator for each relay.
- FR-4 Fiber glass PCB ( Double Layer ).
- PCB thickness: 1.6mm.
- Size: 103 x 51 x 16 mm .
- Power Supply: 5V DC / 70mA (relay all ON).
Input control signal voltage:
- 0V - 0.5V Low stage (relay is OFF),
- 0.5V - 2.5V (unknown state).
- 2.5V - 5V High state (relay is ON).
Input control signal high state current:
- 2.5V: 0.1mA
- 3.3V: 0.18mA
- 5V: 0.35mA
- Voltage: 5V DC.
- Current: 8.3mA.
- Resistance: 2880 ohm +-10%.
- Contact Resistance: <0.1 ohm.
- Contact Capacity: 125V AC / 1A, 30V DC / 2 A.
I use this in a remote controlled preamp. Each relay provides one stereo switch. Easy to drive from an Arduino. The only thing that's not ideal is that it powers up in a random state, but I think that's more down to how it's controlled, and not a flaw in the board, which simply sets the relay based on inputs. Easy to wire up, robust, no problems.
This relay board needs to have a resistor change to drive it from 3.3 volts reliably. Other than that, it is good to go with a Raspberry Pi. I replaced the 1k resistor with a 680 ohm and removed the 10k ohm resistor since the Raspberry has it's own pulldown resistors on the GPIO bus. I2c port expanders like the MPC 23017 also have pulldown resistors.