Or SCABRS for short (don't you just love Acronyms ? ). Several threads recently have inquired about Wireless remote sensors especially at the low cost end of the market. This is my take on how to do it really cheaply, total outlay around £20 ($32 ish). Its 2 parts, the home made Arduino clone which uses the same circuit as the Modern Devices RBBB ( http://moderndevice.com/RBBB_revB.shtml
) which is helpfully in the public domain (it has a pin 13 LED and resistor, which the RBBB doesn't have) , and its shield which contains a Dallas DS18B20 digital thermometer, a Seeed Studios 433 mHz transmitter ( http://www.seeedstudio.com/depot/433mhz-rf-link-kit-p-127.html
) and a LDR. Both are built on offcuts of stripboard with a few components I bought especially. If you're in the UK http://www.bitsbox.co.uk/
sells everything (they didn't have a 328 with a bootloader which I bought off ebay) they do sell a plain 168 if you're prepared to burn your own bootloader. The transmitter came straight from Seeed.
It measures the light level and temperature of anywhere in range of the receiver. The Main board has a standard 6 pin interface for a FTDI Cable or similar USB to TTL serial interface so it can be programmed without too much difficulty although if you really wanted it as cheap as possible, program the ATMEL 328/168 in a separate Arduino and plug it in.
The 'shield' , an even smaller offcut of stripboard with a socket for the transmitter (disn't fancy soldering it directly), dallas DS18B20 and its 4.7k pullup resistor, and an LDR with a 10k resistor in a voltage divider.The 8 pin shield cunningly straddles 2 Analogue pins, 2 Digital (3 including 13), 5v and ground altogether on one side of the chip. The transmitter and the Dallas use a digital each and the LDR uses an analogue - 1 spare for future expansion
. In true cheapskate fashion, the pins on the shield are resistor lead offcuts soldered straight into the stripboard using a socket as a jig. The brown and white wire is a 35cm long (half wave ;D )antenna for the transitter.
This is for the reasonably experienced, if you're struggling coming to terms with Blink and an LED, leave it alone.
Stripboard needs a steady hand to solder if you're used to nice solder resist commercial boards....
The transmitter uses the virtualwire library (linked from the Seeed page above) and onewire for the Dallas. If you're experienced enough to make the board, writing the sketch is easy.