Home automation project sending telemetry using a low-cost ISM-band (433MHz) transmitter.
This is a change of plan from what I originally intended to use (the RFM69HW modules), but with several home automation solutions easily available I decided to make use of these modules instead.
This is the bare transmitter module.
Here is the transmitter module wrapped in heatshrink and stuck on top of an Arduino Nano
Making the overall form factor even smaller by contemplating putting it on a Digispark board.
The benefit is that the ATtiny85 modules are fairly cheap and can hold up to 8kB of program memory. A quarter the size of the ATMega328 Arduino but probably still more than enough to send some telemetry.
This is the module fitted onto a custom PCB that has the ATtiny85 on the underside.
Source code: File:0139 remote 433MHz transmitter v0.5.ino.zip
0139 433mhz transmitter bill of materials -- PCB v1.4 R1 1206 20k R2 1206 4k7 R3 1206 1k R4 1206 10k R5 1206 10k R6 1206 4k7 C1 1206 1uF C2 1206 1uF C3 1206 1uF C4 1206 1uF U1 SOIC ATTiny85 U2 TO-92 DS18B20 U3 TSOT23-5 NCP718ASN330T1G T1 SOT23 (N-Ch FET) BSS138 or Si2302DS T2 SOT23 (P-Ch FET) NDS352AP or BSH203 T3 SOT23 (P-Ch FET) NDS352AP or BSH203 D1 1206 LED