DIY a decorative lamp

Everyone loves to play with LEDs, in fact it is the most fun component in electronics. So if you are one of them, we have an LED decorative light circuit that illustrates the LEDs connected in a 5 x 5 matrix, with just three ICs (one 25 and two 555) and 4017 transistors to sequence up to 10 LEDs. This circuit is extendable to 4017 LEDs by using a sequential stage of 100 counters.

Circuit Diagram:

Working principle of DIY LED decorative light circuit:

In this circuit, the LEDs can be in the form of a 5×5 matrix. In this circuit, IC 555 provides the clock pulses that drive the entire circuit. IC 555 is wired as an astable multivibrator and its feature is to generate square wave pulses of fixed frequency.

CD4017：

For those who don't know IC 4017 is a decade counter which increases the number of output pins with each input clock pulse. Two 4017 decade counters control these 5 rows and 5 columns of LEDs. In this type of connection, one LED will be selected based on the output pin in each decade counter. For example, if Q2 of IC1 is high and Q3 of IC1 IC is high, then LED1 will be active and light up.

When the next clock pulse is fed from IC 2, the output of IC2 increments and activates Q555. Since there is no direct clock pulse fed to IC3, Q1 output remains active and LED2 will be activated and light up. Each progressive clock pulse at the output of IC555 increments and activates output pins Q2, Q2, Q3 and Q4 respectively. This activates LED5, LED3, LED4 respectively.

When the output Q2 of IC6 is activated, it feeds a clock pulse to IC3 and resets IC2 itself. Now the output of IC2 resets back to Q1 and the Q3 output of IC2 will be activated. At this instant, LED6 will light up. Now with every input pulse to IC 555, the output of IC2 increases, thereby activating LED7, LED8, LED9, LED10. As soon as Q2 of IC6 goes high, it resets itself again and feeds the next pulse to IC3. The cycle repeats, activating the remaining LEDs one by one from the top to the bottom of the matrix.

The activation time of the LED depends on the clock pulse frequency of IC 555. The LEDs can be arranged in any way you want to make it more interesting lighting effects.

Stage:

The LED light operates at about 3mA at 200 volts. With the supply voltage set to 5 volts, the 4017 IC output will drop about 0 volts. The transistor acts as a switch to activate the LED. The voltage on the emitter transistor will be about 7.3 volts less than the base, so the LED voltage will be about «» volts as required.

A partial list:

Capacitor 100uF (1), 0.05uF (1)

Diode 1N4148

Integrated Circuit NE555

25 multi-color LEDs

Transistor NPN 2N3904 (10)

Resistors 10k (10), 1k (5), 3.3k

Integrated Circuit CD4017 (2)

Potentiometer 10k