SIMPLEST TEMPERATURE TELEMETRY

I've been asked to build quickly a small and cheap temperature telemetry tx for a friend of mine; i decided to use what i had laying around: some ic samples from Micrel and MAXIM.

This simple design used a Maxim temp. to freq. ic to modulate via OOK (on the enable+ask pin) a micrel ask PLL 433mhz ism band transmitter.

The other ic used is, in fact, a micrf113, which provides about 10mW of output power and is crystal controlled, hence very thermally stable in frequency. 

The open field tx range was great; this units had a suprising low power consumption and the downlink was just a matter of deciphering the frequency of a square wave audio signal.