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Project Timekeeper

Keep track of several projects at once using a PIC16F84

Project Timekeeper
This special timekeeper records individual time periods and adds them together to produce a total time. The circuit uses a real-time clock device, backed up by a ‘Goldcap’ capacitor.When working on a project the time spent in each individual work session often needs to be recorded. Written notes may be made as follows: Period 1: October 7 from 8:13 to 8:55 Period 2: October 7 from 8:56 to 9:32and so on. The differences between the recorded times must be worked out, and then added together to arrive at the total time spent. The device described here was developed to simplify this task. It can keep track of the total time spent on up to nine separate projects. Indeed, it can be used to measure time durations in any application as long as no great precision is required: for example, the duration of a competition, or the operating time of (household) equipment, or the length of an experiment.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor 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. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

R1 = 270Ohm
R2 = 1kOhm
R3 = 33kOhm
R4 = 22kOhm
R5,R6,R7 = 470Ohm
R8 = 10kOhm
P1 = 10kO preset H
C1,C2 = 22pF
C3 = 100nF
C4,C6,C7 = 10µF 25V radial
C5 = 100mF 5.5 V Goldcap
D1-D5 = 1N4148
T1 = BC557
IC1 = PIC16F84-10P, programmed, order code 020350-41
IC2 = DS1302
IC3 = 4011
IC4 = LP2950CZ5.0 (low-drop voltage regulator, 5V, TO92 case)
K1 = 14-way pinheader
K2 = 7-way socket strip
BZ1 = buzzer, 5 VDC
BT1 = 9V battery (6F22) with clip-on leads
X1 = 10MHz quartz crystal
X2 = 32.768kHz quartz crystal
S1 = on/off switch
2 x 16 character alphanumerical LCD Module
Telephone keypad (4x3 matrix), e.g., Conrad Electronics # 709840
PCB, available from The PCBShop
Disk (source & object code), Free Download
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