Article

Electronic Knotted Handkerchief

A microcontroller-based notepad

How many times has the birthday of that rich uncle or that six-monthly appointment at the dentist slipped your mind? How many times have you forgotten to put out the rubbish? The solution is either a little mental training — or the idea presented here: an electronic knotted handkerchief.Key features– Space to store from 48 to 94 appointments (depending on the number of distinct events)– Schedule appointments up to 22 months ahead– Set times in steps of one hour– Advance notice period settable from 0 to 255 hours in steps of one hour– Appointments displayed for a period from 0 to 124 hours (without advance notice), settable in units of four hours– Battery life: one to two years using four alkaline AA cells (depending on duration and frequency of displayed appointments)

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Materials

020308-PCB.pdf

020308-11.zip

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

Download Gerber file: 020308-1.zip

Component list

Resistors:
R1 = 10k?
R2,R4 = 22k?
R3,R5,R14,R20 = 100k?
R6-R13 = 1k?
R15 = 3M?3
R16 = 15k?
R17,R18,R19 = 4k?7
R21 = 56k?
R22 = 180k?
R23 = 47k?
P1 = 100k? preset
Capacitors:
C1,C6 = 100µF 10V radial
C2 = 80pF trimmer
C3 = 82pF
C4,C5 = 100nF
C7-C10 = 1µF 10V radial
Semiconductors:
D1-D8,D11 = LED, red, low current
D9,D10 = 1N4148
IC1 = AT90S2313-10PC, programmed, order code 020308-41
IC2 = 4060N
IC3 = 4013
IC4 = 40106
IC5 = MAX232
T1 = BC338
T2,T4 = BC328
T3 = BC327
Miscellaneous:
BT1 = 4 AA or AAA batteries with holder
K1 = 9-way sub-D socket (female), PCB mount, angled pins
X1 = 32.768kHz quartz crystal
Disk, order code 020308-11 or Free Download