hand wash timer (digital logic)

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STD hand wash timer (digital logic)

License: MIT

Mode:

Editors' pick

Cloned from hand wash timer

Update time： 2021-11-15 03:02:58

Creation time： 2020-07-14 08:02:30

Description

This is a little timer you can put next to your sink in the kitchen or bathroom. When you wash your hands, wave your hand in front of the IR detector, and it will count down 20 seconds to make sure you wash your hands for long enough. Stay safe and healthy!

Design Drawing

schematic diagram

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Schematic
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PCB

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Logic on back
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Logic on front
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BOM

BOM download Purchase Parts

ID	Name	Designator	Footprint	Quantity
1	8.3uF	C1	RAD-0.2	1
2	10nF	C2	RAD-0.2	1
3	10uF	C3	RAD-0.2	1
4	1N4148	D1,D2	DO-35_BD2.0-L4.0-P8.00-D0.5-FD	2
5	NAR141SH	LED1,LED2	LED-SEG-TH_10P-L10.0-W12.9-P2.54-S7.52-TL	2
6	LED-TH-5mm_IR	LED3	LED-TH_BD5.0_RED	1
7	PT-TH-5mm_IR	PT1	LED-TH_BD5.0_RED	1
8	BS170	Q1	TO-92-3_L4.9-W3.7-P1.27-L	1
9	2N3904(TO-92)	Q2,Q3	TO-92-3_L5.1-W4.1-P1.27-L	2
10	2N3904	Q4	TO-92-3_L5.1-W4.1-P1.27-L	1
11	5.1k	R1,R13	R_AXIAL-0.4	2
12	100k	R2,R3	R_AXIAL-0.4	2
13	10k	R4,R5,R11,R12	R_AXIAL-0.4	4
14	4.7k	R6	R_AXIAL-0.4	1
15	220	R7	R_AXIAL-0.4	1
16	68k	R8	R_AXIAL-0.4	1
17	33k	R9	R_AXIAL-0.4	1
18	10k OR 15k	R10	R_AXIAL-0.4	1
19	1k	R17,R18,R19,R20,R21,R23,R24,R25,R26,R27,R28,R29,R30	R_AXIAL-0.4	13
20	150	R33	R_AXIAL-0.4	1
21	NE555P	U1	DIP-8_L9.8-W6.6-P2.54-LS7.6-BL	1
22	CD40192BE	U2,U6	DIP-16_L19.2-W6.6-P2.54-LS7.6-BL	2
23	SN74LS247N	U3,U5	DIP-16_L19.2-W6.6-P2.54-LS7.6-BL	2
24	USB4085-GF-A	USB1	USB4085-GF-A	1