Contactless Thermometer

Are you running an infrared temperature?

Published in issue 2/2011 on page 48

This thermometer measures at the same time both the ambient temperature and the temperature of any object placed within its ‘field of view’. And even though the ambient temperature range ‘only’ goes from −40 to +125 °C, the object temperature can be from −70 to +380 °C, and all with an accuracy of 0.5 °C and a measurement resolution of 0.02 °C.

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Products

Components

Resistors (0.25W 5%)
R1,R4,R6 = 10kOhm
R2, R5 = 100Ohm
R3 = 1.5kOhm
P1 = 10 kOhm trimpot, horizontal
Capacitors
C1,C3 = 100µF 16V, radial, lead pitch 2.5mm
C2 = 470nF 63V, MKT, lead pitch 5 or 7.5mm
C4 = 10µF 25V, radial, lead pitch 2.5mm
C5, C8 = 22pF ceramic, lead pitch 0.2’’ (5.08mm)
C6 = 100nF ceramic, lead pitch 5 or 7.5mm
C7 = 10nF ceramic, lead pitch 5 or 7.5mm
Inductors
L1 = 10µH, Panasonic type ELC08D100E (RS Components)
Semiconductors
IC1 = LT1300
IC2 = PIC16F876A-10E/SP, programmed, Elektor # 100707-41
D1 = 1N5817 (must-have Schottky)
D2 = 3.3V 0.4W zener diode
Miscelllaneous
Sensor type MLX90614ESF-BAA or MLX90614ESF-AAA (see text)
LCD1 = LCD, 4 lines of 20 characters, e.g. Displaytech 204A
X1 = 20MHz quartz crystal, HC18/U case
S1 = pushbutton, 1 make contact, ITT type D6 if fitted on PCB
S2 = swich, changeover, or wire link
DIL IC sockets: 1 pc 8-way; 1 pc 28-way
Pinheder pins, lead pitch 0.1’’ (2.54mm)
Pinheder sockets, lead pitch 0.1’’ (2.54mm)
PCB, Elektor # 100707-1