• on Test & Measurement
  • Published in issue 1/2008 on page 16
About the article

CO2 Measurement

Stuffy air alert

CO2 Measurement
Carbon dioxide (CO2) is not just a threat to the environment, it is also an important and often ignored factor in determining air quality in the office and at home. Too high a concentration of CO2 leads to feelings of tiredness, disturbs concentration, and causes headaches. The CO2 meter described here makes it easy to determine the concentration of carbon dioxide in the air. A microcontroller monitors the measured value and can trigger an alarm or start up a ventilation system when a preset threshold is exceeded.
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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

Update February 22, 2008

New firmware and source code file in archive -11; change log in C file.

- content sorted and cleaned, bugs fixed

- added TODO list.

R1,R3 = 10kΩ
R2 = 1kΩ
R4 = 47kΩ
R5 = 33Ω
P1 = 10kΩ preset
C1,C2 = 10µF 25V radial
C3,C4,C5,C7 = 100nF
C6 = 10µF 25V radial
D1,D3,D4 = 1N4001
D2 = LED, low-current
T1 = BC547B
IC1 = 7805
IC2 = ATtiny26-16PC, programmed, Elektor Shop # 070802-41
L1 = 10µH
Re1,Re2 = 5V-Relay, SPDT, 250V/10A AC, e.g. Panasonic JW1FSN-5V
LC Display, 2x16 characters, e.g. Displaytech 162
Figaro CO2 measurement module type CDM4161 or CDM4161A (see text)
PCB, Elektor Shop # 070802-1 or kit of parts # 070802-71 (all parts, PCB, programmed ATtiny, and CO2 module)
Project software and PCB layout
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