# Led Clock

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## Introduction: Led Clock

Hello everyone....

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
3. 1N4007
4. 220 E/1Watt Resistance
5. 10uf/450Volt Electrolytic Cap
6. 1 M / 1/4 Watt Resistance

For Green Led
We Use:-
1. 474K/400V
2. 10E/1 Watt Bleeder
3. 1N4007
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.
So,
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.

## Recommendations

Following points are responsible for the series connection.

1. The parallel array takes more current from source since current gets divide ,so we have to choose higher value of metallized polyster capacitor.

2. The value of Output Cap needs to be changed to higher since more current would filters out.

3. Comparatively Complex and Bulky Wiring which takes more time and resources.

4. Cost and Size of Circuit also becomes high.

At last the only advatange with being in parallel network is safer voltage level can be easily acquired which do not gives shock.
Also note that Only Voltage is high in this circuit , Current is in milli Ampere (around 35 to 60mA).So it is not so dangerous as it seems to be.

Thanks.