Introduction: Led Clock
This clock uses
150 Red 5mm Led (2 V/10mA)
61 Green 5mm Led(3.4V/20mA)
and a clock machine.
Step 1: Unregulated Capacitive Power Supply
For Red Led
We Use :-
1. 105K/400V Metallized Polyster Capacitor
2. 47E/2Watt Bleeder Resistance
4. 220 E/1Watt Resistance
5. 10uf/450Volt Electrolytic Cap
6. 1 M / 1/4 Watt Resistance
For Green Led
2. 10E/1 Watt Bleeder
4. 220E/1Watt Resistance
5. 10uf/250 Volt Electrolytic Cap
6. 1 M/ 1/4 Watt Resistance
Step 2: Circuit Diagram
The circuit is quite simple as it is the most common transformerless power supply.
The calculation for measuring current through Capacitor is given in the diagram itself.
Now we are calculating the power consumption by applying simple formula i.e. P= V x I
"The readings was taken when circuit is connected to A.C mains.
So be very careful about not to short circuit with multimeter wire pins."
The total potential difference across series of Red Led comes about 286 Volts with average current of 7 mA.
Power = 286 V x .007 A
= 2.002 Watt
and for Green Led same procedure applies,
Power = 182 V x 14.5 mA
= 182 V x 0.0145 A
= 2.639 Watt
Power loss through resistors is assumed to be less than 1 Watt.
Total power Consumption= 2.002+2.639+ loss in Resistors
= 4.641 + 1 watt maximum
= 5.641 Watt
Step 3: Board Dimensions
Square Card board has been used of side = 12 inch or 1 feet.
The radius of Clock Circle is around 12.5 Centimetre. Just arrange the led in a format of clock and you are done.
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