6. Components

Table of components

Part Qty Value Function
IC1 1 ATmega88 main microcontroller
IC2 1 LM7805 voltage regulator (+5V)
C1,2 1 22 uF capacitors for LM7805
C3 4 10 nF key debouncing
C4 5 100 nF decoupling capacitors
D1,2 1 1N4004 diodes for power supply system
R1 1 4.7 kΩ current limiting resistor for PD0 line
R2 1 10 kΩ pull-down for PD0 line
R3 4 150 Ω used for input
R4 4 10 kΩ used for input
R5 4 4.7 kΩ used for output
R6 4 560 Ω used for output
R7 1 10 kΩ /RESET line pull-up
T1 4 BC457 npn transistor for LEDs
X1 1 32.768 kHz RTC oscillator
Bat 2 AAA batteries for auxiliary power supply
LED 1 LED stripe light source
H1 3 6-pin 6-pin headers for interconnection
H2 1 socket power supply socket
H3 3 14-pin nest for the microcontroller
H4 1 AAA battery holder
PB 4 push-buttons for input
SW 1 power switch for restarting

Useful links

No. Link
1. Colour-Temperature Relationship
2. Paul Burgess: "Variation of the colour intensity..."
3. Luminosity and Sunlight: Q&A
4. CIE Chromaticity Diagram explained
5. Chromaticity Calculator
6. More on the Chromaticity Diagram
7. Colour-Temperature Relationship
8. Using transistors for driving LEDs
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