About the article

Cloud Altitude Meter

your head in the clouds with AirControl

Cloud Altitude Meter

This circuit was dubbed AirControl because it indicates the altitude of the clouds by measuring air temperature and humidity and then silently doing a mass of scientific calculations. It should make an interesting meteorological tool for people who keep an eye on the sky.


AirControl Reservation Form (Elektor Shop item 090329-91)

The module is not yet available in our online shop, we are first gauging the interest in this unique product. Please complete the form if you are interested in purchasing an AirControl module. If sufficient feedback is received the module will be taken into production.
To Reservation Form

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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Extra info, Update

* MCU: Atmega324PA-AU from Atmel, JTAG support
* SHT11 humidity sensor from Sensirion, 0–100 % RH, accuracy 3 %
* Powered by three AAA/R6 penlight cells
* Minimum battery life one week (with new batteries and without using the backlight)
* Works out the cloud base altitude
* 4 line × 20 character display
* Portable, sensor on detachable breakout board

Resistors (SMD 0805)
R1–R4, R7 = 10kOhm
R5, R6 = 1kOhm
R8, R9 = 10Ohm
P1 = 10kOhm SMD preset (Vishay TS53)
Capacitors (SMD 0805):
C1,C9 = 2.2µF 10V 10% tantalum (ESR 8Ohm)
C2–C8,C10,C11 = 100nF
D1,D2 = LED, red, 3mm, high efficiency
D3 = 1N4148 (SMD version: LL4148)
T1,T2,T3 = 2N7002, n-channel MOSFET
IC1 = LP2980AIM5-3.3, 3.3V / 50mA, regulator
IC2 = ATmega324PA-AU,programmed
IC3 = SHT11
X1 = 32.768kHz oscillator module, CL = 6pF (Epson Toyocom MC-306)
LCD1 = 4x20 characters (Electronic Assembly EA DIP204-4NLED)
BZ1 = miniature resonator (CUI CST-931RP/A)
S1 = micro slide switch (EAO 09-10290-01)
S2-S4 = pushbutton, SPNO, 12V / 50mA, 6x6 mm – 13 mm, Tyco Electronics FSM14JH
K1 = 6-pin SIL pinheader, lead pitch 0.1 in. (2.54mm)
K2, K6 = 6-pin pinheader, double row, angled pins, lead pitch 0.1 in. (2.54mm)
K3, K4 = 4-way pin receptacle, lead pitch 0.1 in. (2.54mm)
K5 = 6-pin SIL pinheader, lead pitch 0.1 in. (2.54mm)
Enclosure, Bopla type BOS400 Streamline with battery compartment for 3 AAA cells (Bopla # BS 401 F-7024 ) and decorative fixing (Bopla # BS 400 DI-D-7024)
PCB # 090329-1 [11]
Front panel design, to print and cover with plastic foil, # 090329-F [11]
Complete kit (with SMD parts soldered on board)

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