LV-0 Independent Logging Altimeter
Adept RA3A Logging Altimeter (Front)
Adept RA3A Logging Altimeter (back)
Thanks toJames Ward for lending us his Adept RA3A altimeter. Basically, the Adept uses a Sensym pressure sensor to make pressure measurements. The voltage coming out of the SCC15A is digitized using a cute little Harris 8pin 12bit Analog to digital converter (ADC) with serial output. This serial data gets eaten by a huge (64pin dip) Motorola 68HC11 which logs it on 32K worth of Microchip serial EEPROM. To increase the cuteness factor (but increase the weight and sillyness quotient), the board has an onboard LCD and buttons for an effective but heavy user interface. It's also got an RS-232C port to hook up to dump the logged data.
The altimeter requires you to "zero" the altimeter pre-launch, and then the altimeter converts the data to altitudes. At 12 bit resolution, it should get to a 9ft resolution. The launch detect is primitive but seems to work; a massive bar on a pivot which closes a microswitch. Their new generation ones have accelerometers which, frankly, makes more sense.
Although a fine board, it is clearly an older model and not that well designed. The new generation adepts are much better designed and I'm sure don't have the tendency to "pop" their 9V batteries. Ahem. Anyway, it worked great for us.
For more information on all of this junk, feel free to contact us at firstname.lastname@example.org!