Meeting Cost Timer
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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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Extra info / Update
- 70 mm tall 7-segment displays
- Maximum total displayed: 9999.99
- Single switch operation using rotary encoder with press-button function
- Connections and operating control can be mounted on either the right or left-hand side of the PCB
- Controller: ATMega168-20PU
- ISP adapter for programming
- Power supply using 12 V / 800 mA mains adapter
Component list
(all 0.25W, 5%)
R1 = 220O
R2-R8 = 150O
R9 = 10kO
Capacitors
C1 = 330nF, ceramic, lead pitch 5mm
C2 = 10µF 16V
C3-C8 = 100nF, ceramic, lead pitch 5mm
Semiconductors
D1 = 1N5817 (Schottky diode, 1A)
IC1 = LM7805 (TO220 case)
IC2,IC3 = L293DNE, DIP16 case (Farnell # 1470423)
IC4 = ULN2803A, DIP18 case (Farnell # 1047761)
IC5 = 74HCT238, DIP16 case (Farnell # 382231)
IC6 = ATmega168-20PU, DIP28 case, programmed, Elektor SHOP # 080396-41
IC7 = PCF8583P, DIP8 case (Farnell # 403908)
LD1-LD6 = SA23-12SRWA (Kingbright), 7-segment LED display, red, common anode (Farnell # 1168639)
Miscellaneous
X1,X2 = 32768 Hz quartz crystal, cylindrical housing 3x8mm
K1,K2 (optional) = mains adapter connectors for PCB mounting
K3 = 6-way DIL pinheader, lead pitch 2.54 mm (Farnell # 1096984)
S1,S2 (optional) = EC11B15242 (Alps), rotary encoder for front panel mounting, 11mm (Farnell #1191733)
PCB no. 080396-1 from the Elektor SHOP
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