Article
Minimalistic Time Switch
A lot of features in a small package
A time switch lets you save a considerable amount of energy by switching off equipment when it is not being used. However, time clocks from building merchants tend to be bulky and not especially easy to use. The circuit described here provides a distinctly larger set of features and is very compact, so it can easily be built into an existing piece of equipment.
Materials
Gerber file
CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD 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.
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PCB
Component list
Resistors
all SMD 0805
R1 = 390Ohm
R2,R3,R4 = 4.7kOhm
R5,R6 = 22kOhm
R7 = 180Ohm
Capacitors
C1 = 2.2µF, SMD 0805
C2,C4 = 100nF, SMD 0805
C3 = 470µF 6.3V, or GoldCap 0.1F or 1F 5.5 V (see text)
Semiconductors
all SMD, except D3
D1,D3 = LL4148
D3 = LED, red, 3mm
T1,T2 = PMV45EN
IC1 = MAX1615EUK+T
IC2 = DS1337S+
IC3 = PIC12F683-I/SN, programmed, Elektor Shop # 090823-41
Miscellaneous
X1 = 32.768kHz (CL = 6pF!, e.g. Farnell # 1216227)
S1 = pushbutton SPNO, 6mm (MCDTS6-5N)
K1 = 4-pin SIL pinheader
K2 = 5-way SIL socket
K3 = 2-pin SIL pinheader
PCB, # 090823-1
Project software # 090823-11.zip (source- and hex code file)
all SMD 0805
R1 = 390Ohm
R2,R3,R4 = 4.7kOhm
R5,R6 = 22kOhm
R7 = 180Ohm
Capacitors
C1 = 2.2µF, SMD 0805
C2,C4 = 100nF, SMD 0805
C3 = 470µF 6.3V, or GoldCap 0.1F or 1F 5.5 V (see text)
Semiconductors
all SMD, except D3
D1,D3 = LL4148
D3 = LED, red, 3mm
T1,T2 = PMV45EN
IC1 = MAX1615EUK+T
IC2 = DS1337S+
IC3 = PIC12F683-I/SN, programmed, Elektor Shop # 090823-41
Miscellaneous
X1 = 32.768kHz (CL = 6pF!, e.g. Farnell # 1216227)
S1 = pushbutton SPNO, 6mm (MCDTS6-5N)
K1 = 4-pin SIL pinheader
K2 = 5-way SIL socket
K3 = 2-pin SIL pinheader
PCB, # 090823-1
Project software # 090823-11.zip (source- and hex code file)
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