- on Home & Garden
- Published in issue 6/2012 on page 14
Nixie Thermometer / Hygrometer
Tubes, sensors and a micro in a single design
Measuring temperature and humidity with a modern sensor and displaying the values on a retro display — it’s all described in this article. A calibrated, ‘digital’ sensor provides data via its I2C interface to a microcontroller driving four Nixie tubes and automatically alternating between temperature and humidity, while providing a nice fading effect. It’s a must-have!
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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.
The BOM (Bill of Materials) is the technically exhaustive listing of parts and other hardware items used to produce the working and tested prototype of any Elektor Labs project. The BOM file contains deeper information than the Component List published for the same project in Elektor Magazine. If required the BOM gets updated directly by our lab engineers. As a reader, you can download the list here.
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R1-R4 = 22kOhm
R5,R11,R12 = 10kOhm
R7 = 47kOhm
R8 = not used
R9 = 820kOhm
R10 = 330(
R13 = 5.6kOhm
R14 = 470kOhm
R15 = 4.7kOhm
R16 = 150(
C1-C4 = 100pF 2000V, 10%, radial, 5mm pitch (Farnell #1141797)
C5-C8,C11,C12,C16-C18 = 100nF 50V, 20%, pitch 5mm
C9, C10 = 33pF 100V, 5%, 2.54mm pitch
C13 = 10µF 250V, 20%, radial, 5mm pitch
C14,C15 = 100µF 25V, 20%, radial, 2.5mm pitch
C19 = 470pF, 100V, 10%, 5mm pitch
L1 = 330µH 1A, 20%, axial, D×L = 11×32.5 mm (0.43”×1.28”) max.
D1 = BYV26
D2-D4 = 1N4001
IC1-IC4 = 74141 or K155ID1 (?155??1)
IC5 = PIC16F876-20/SP
IC6 = 7805
IC7 = MC34063
IC8 = SHT21 I2C humidity and temperature sensor  (Farnell #1855468)
T1,T2 = MPSA42
T3 = IRF820
X1 = 6MHz quartz crystal
V1 = IN-19A, Nixie Tube (symbols)
V2-V4 = IN-14, Nixie Tube (numeric)
K1 = 2-way PCB terminal block, 5mm pitch
PCB # 110321-1