Sometimes, electronics can offer a quite playful dimension. With 13 LEDs of various colors and a very simple circuit, we are able to create some colorful bright alternating patterns.
The electronic circuit of the LED - shapes flasher is shown in Figure 2. We use the 555 as a time base oscillator. It produces a clock signal at a frequency which is determined by the elements R1, R2, R3 and C1. The clock signal is then applied to the input of a 4017 counter. The 4017 is configured as a modulo 6 – counter (counts 0,1,2,3,4,5, 0, 1, 2 …..). Only one Q output of the counter is active at any instance and the Q outputs are used to activate some groups of LEDs. There are four groups of LEDs. These groups are:
Group 1 - [DL1]
Group 2 - [DL2, DL3, DL4, DL5]
Group 3 - [DL6, DL7, DL8, DL9]
Group 4 - [DL10, DL11, DL12, DL13]
By using the counter and the diodes D1-D5, the groups of LEDs are activated sequentially in an endless loop acording to the order: group 1, group 2, group 3, group 4, group 3, group 2.
The resulting LED shapes flasher can be seen in the animation – image 1.
You may notice that the D3 diode is not essential. However, since each diode causes a voltage drop of around 0.7V, we use D3 for voltage compensation, so that all groups of LEDs have the same brightness as possible. Resistors R4 and R5 also contribute to this compensation.
You can easily build the circuit on the printed circuit board of Figure 3 or on a breadboard. If you choose to use the circuit board of Figure 3, then you’ ll have to place and solder all the components to the circuit board according to the assembly guide of Figure 4. You need to be careful about the polarity of the LEDs because some of them are connected in series order an if you place one in a wrong polarity, all LEDs in the same group will be off.
You may also cut the board into two pieces, along the dotted line shown in Figure 4, if you wish so. Then you’ ll have to connect the two pieces with a multi-strand ribbon cable. This way you will be able to place the LEDs in a different place from the rest of the circuit.
All the resistors we use in this project are of 1/4W through-hole type. There are no critical values and you may experiment with different values in order to change the frequency range of the clock or the brightness of the LEDs.
The speed of the alternating shapes is determined by the trimmer potentiometer R2. The circuit needs a power supply from 9 to 15V and the average current consumption is around 15mA.