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Kiddies Toothbrush Timer
The timer presented here is designed to look like and mimic a classic sandglass and should need zero explaining to your kids, the operation being intuitive. If they can switch on the TV and the WiFi router, surely they can operate this timer too. Press the button to start the timer. LEDs light in sequence to imitate sand grains trickling down, and (yes) a modest beep sounds every 30 seconds, as well as when “time’s up”. One LED equals 10 seconds.
Gerber file
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PCB
Extra info / Update
Note: Since the original publication of this project/article, some of the components, software elements, webpages and other elements might have been updated or changed.
Component list
COMPONENT LIST
Resistors
(SMD 0805)
R1 = 1kOhm 1%
R2 = 10kOhm 1%
R3,R4 = 75Ohm 1%
R5–
R16 = 120Ohm 1%
Capacitors
C1,C2,C3 = 100nF 25V, SMD 0805
Semiconductors
D1–D24 = LED, red, SMD 0805, e.g. Kingbright KPHCM-2012SURCK; Farnell # 1686067
D25 = LED, green, SMD 0805, e.g. Kingbright KPHCM-2012CGCK; Farnell # 1686075
IC1 = ATtiny13A-SSH, SO-8 case, programmed, Elektor # 120368-41
IC2,IC3 = 74HC164D, SOIC-14 case
T1 = BC850C, SOT-23 case
Miscellaneous
BT1 = button cell holder and CR2032 battery; Farnell # 2064725
BZ1 = piezo buzzer, Farnell # 1192551
K1 = 6-pin (2x3) pinheader, 0.1’’ lead pitch
S1 = pushbutton, side actuated, Farnell # 1761633
PCB # 120368-1
Resistors
(SMD 0805)
R1 = 1kOhm 1%
R2 = 10kOhm 1%
R3,R4 = 75Ohm 1%
R5–
R16 = 120Ohm 1%
Capacitors
C1,C2,C3 = 100nF 25V, SMD 0805
Semiconductors
D1–D24 = LED, red, SMD 0805, e.g. Kingbright KPHCM-2012SURCK; Farnell # 1686067
D25 = LED, green, SMD 0805, e.g. Kingbright KPHCM-2012CGCK; Farnell # 1686075
IC1 = ATtiny13A-SSH, SO-8 case, programmed, Elektor # 120368-41
IC2,IC3 = 74HC164D, SOIC-14 case
T1 = BC850C, SOT-23 case
Miscellaneous
BT1 = button cell holder and CR2032 battery; Farnell # 2064725
BZ1 = piezo buzzer, Farnell # 1192551
K1 = 6-pin (2x3) pinheader, 0.1’’ lead pitch
S1 = pushbutton, side actuated, Farnell # 1761633
PCB # 120368-1
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