Thermometer using Giant Gottlieb Displays

Original, self-sufficient, and readable from a distance in all weathers

Published in issue 4/2012 on page 56

In this unique project an electromechanical display recovered from a 1960s pinball machine and some modern programming techniques together form a water-temperature indicator for an outdoor swimming pool. Once the temperature is displayed on the 4 inch reels, the consumption of my circuit drops to zero, but the temperature display remains perfectly visible. There are no batteries (dry or rechargeable), adjustments, or maintenance.

 

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Products

Components

Resistors
R1 = 100kOhm
R2 = 470kOhm
R3,R6,R12 = 390Ohm
R4,R8,R13 = 470Ohm
R5.R9,R14 = 330Ohm
R7 = 10kOhm
R8 = 2.2kOhm
Capacitors
C1,C4 = 100nF (5mm)
C2 = 1000µF 35V radial
C3 = 1F 5.5V
C5 = 100nF SMD 0805
Semiconductors
D1–D5 = 1N4148
B1 = 100Vpiv 1.5A bridge rectifier, round
IC1 = 78L05
IC2,IC4,IC6 = S2S3ADYF (triac optocoupler)
IC3 = ATTINY2313-20PU, programmed, Elektor # 110763-41
IC5 = TMP100
Tri1,Tri2,Tri3 = T1235H-6G
Miscellaneous
AC power transformer, 40VA, primary 2x115V, secondary 2x12V (e.g. Block RK40/12)
F1 = fuse, 160mAT @240V (315mAT @115 V)
K1,K4,K6,K9 = PCB screw terminal (5mm)
K2,K3 = PCB screw terminal (7.5mm)
K5 = 3-pin pinheader
K7,K8 = 4-pin pinheader
K10 = 6-pin (2x3) pin pinheader
* pushbutton, 230VAC (USA: 115VAC) rated.
PCB # 110763-1