Nixie Tube Thermometer

Retro temperature display

Nixie Tube Thermometer

In this article we describe the union of a modern microcontroller with a classic display technology to create a novel temperature indicator. In its transparent enclosure the device will set off any mantelpiece to advantage and what’s more, the unit even doubles up as a night light. An external sensor allows the temperature at any desired location to be displayed.

Extra info / Update

Features

Display range: 00 to 99 (Celcius or Fahrenheit)

Temperature sensor: Maxim-Dallas DS1820, accuracy 0.5 K

Power supply: AC power adaptor, 12 V to 15 V DC

Current consumption: 170 mA at 12 V

Tubes: Russian IN-16, 13-way solder connections

Microcontroller: Atmel AT89C2051 (available ready-programmed)

Firmware: BASCOM (source and hex files available for free download)

Options:

- choice of Celsius or Fahrenheit display

- tube illumination

- LED trend (warmer/colder) indicators

Component list

Resistors

R1 = 4.7kOhm

R2,R3 = 220Ohm

R4,R5 = 22kOhm

R6 = 10kOhm

R7 = 1kOhm

R8 = 150Ohm

R9 = 820kOhm

R10 = 5.6kOhm

Capacitors

C1 = 10μF 63V, radial, 0.1 in. lead pitch

C2,C3,C5,C7,C8 = 100nF ceramic, 0.2.in. lead pitch

C4 = 10μF 250V, radial, 0.2 in. lead pitch

C6 = 470pF, 0.2 in. lead pitch

C9,C10 = 100μF 25V, radial, 0.1 in. lead pitch

Inductor

L1 = 330μH, 1A, axial, DxL = 11x32.5 mm max., e.g. Epcos B82500CA8 or Fastron 77 A-331 M-00

Semiconductors

D1,D3,D4 = LED, 3mm, blue

D2 = LED, 3 mm, red

D5 = 1N4004

D6 = BYV26 (e.g. Vishay)

T1 = IRF820 (Vishay, International Rectifier IRF820PBF)

IC1 = AT89C2051-24PU, programmed, Elektor # 090784-41*

IC4 = DS18S20 (Maxim/Dallas)

IC5 = MC34063

IC6 = 7805 (TO220)

Miscellaneous

X1 = 12MHz resonator, 3-pin, e.g. AEL Crystals type C12M000000L003

JP1 = 2-pin pinheader, 0.1 in. lead pitch (optional jumper, see text)

K1 = 2-way PCB screw terminal, lead pitch 5mm

PCB # 090784-1