Timer Switch for Washing Machine
Switching on command
Published in issue 350, January 2006
Many households have a utility supply with a separate day/night tariff, where the electricity board delivers cheaper power during the night and weekends. It can be economical to use, for example, the washing machine at that time. That is, as long as you’re actually there to turn it on at the right time, because modern electronically driven washing machines cannot be delayed with a simple timer switch. But with a handful of components you can build yourself a circuit than can actually do this!
Resistors:
R1,R18 = 1k
R2 = 100
R4-R7,R9,R10,R12,R13 = 150
R8,R11 = 470
R3,R14-R17 = 10k
Capacitors:
C1 = 47µF 16V radial
C2,C3,C6 = 100nF
C4,C5 = 100pF
Semiconductors:
B1 = B40C1500R bridge rectifier (40V piv, 1.5A)
D1-D6 = 1N4148
D7,D8 = LED, red, 3mm diam.
IC1 = 78L05
IC2 = PIC16F84, programmed, order code 050058-41
LD1-LD4 = 7-segment display, e.g. Fairchild type MAN4710A
T1 = BC547B
T2-T5 = BC558
Miscellaneous:
F1 = fuse, 100mAT (slow) with PCB mount holder
K1,K2 = 2-way PCB terminal block, lead pitch 7.5mm
K3,K3' = 3.5mm stereo jack plug with socket
R1 = 12V relay (e.g. Siemens V23057-12V)
S1,S2 = pushbutton (e.g., ITT D6-R-90)
Tr1 = mains transformer, 230V primary, secondary 9V @ 1VA (e.g. Block VB1,0/1/9)
X1 = 32.768kHz quartz crystal
PCB, order code 050058-1
PIC source and hex code, code 050058-11
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Click below to download a PDF copy of this article from Elektor magazine. Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.
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