Relay Receiver
Overview
The relay receiver is a simple receiver-only device which accepts on/off/pulse commands to switch the four individual ports on and off. This circuit has four relays attached to it, but can easily be adapted to just one or any other imaginable circuit to be turned on and off remotely. It can be used to turn on/off lamps, open garage doors or remote control your sprinklers if you so wish. Be sure to size your relays accordingly depending on the load getting switched.
The circuits contains a regulated power supply by the means of a 7805 regulator — this can be skipped if a regulated 5V power supply already exists.
Worthy mentioning is the DIP switch attached to the MCU which sets the device ID for the wireless protocol (4 lines = 4 bits).
Required Hardware
The circuit uses the following hardware (links go to Sparkfun, you can also easily get this from Digikey, Mouser, etc):
- RES1: 16MHz Resonator
- MCU1: ATTiny2313-20, 5V
- IC1: 7805-style power regulator
- T1,T2,T3,T4: NPN transistor such as 3904
- R1, R2, R3, R4, R5, R6, R7: 470Ω
- D1,D2,D3,D4: Diodes such as 4148 to protect the circuit as we’re switching an inductive load (relay)
- R8,R9,R10,R11: 1kΩ
- C1: 100μF, C2: 10μF capacitors
- RFRecv: 2400 MBps SAW receiver module
- REL1,REL2,REL3,REL4: 5v relays such as this
All of the components can easily be mounted on a breadboard for prototyping.
Circuit
Grab the Eagle diagram or image thereof.
Firmware
The firmware is built around the common Catrpillr libary and can be found right here. See the software section for details around firmware and uploading firmware.