From my experience, if you plan to make temperature and light measurements, the sensors shall be placed outside the insulated nacelle at the end of a rod a few tens of cm away. If you let the sensors near to the nacelle's surface your measurements will be very disturbed by the thermal effects and the light reflecting on the nacelle.
Also, don't forget to get a radar reflector to make your system detectable by airplanes...
[quote author="BrentBXR"]I dont understand what the MAX232 is doing. It has the communication likes (both TIN and TOUT) going to one ultrasonic speaker? Is that perhaps to generate higher voltage? Also do you have more details on this? Non of the parts are marked, how do you know what resistors to use, caps to use, and so on.. Or even what voltage that VCC should be.[/quote]
Hello!
The MAX232 in US rangers is a "classical" trick. It's used as an amplifier to drive the piezo US emitter which ideally needs a differential "high" voltage swing to "ring" properly. The TTL signal from the PIC is converted by the MAX232 in a +-10V (Then 20V in total amplitude) voltage swing thanks to the charge pumps.
