Multi-color LED driver

Have you ever wondered how many different colors can illuminate a LED? One, two or maybe three? Constructing this simple circuit, you will find it much more. The key component in this design is a dual LED. One such accessory includes two inside the 'slices' of different diode LED, that each of them produces a different color (usually green and red). For the drive requires three pins, a common cathode and two separate roots. In this way each of the two integrated diodes can light up as independent of each other. There are only two colors that can produce this dual LED.
Multi-color LED driver - schematic

Setting appropriate percentage of the currents flowing through two separate channels of the POY is, we have other from pure green and red, orange (IR = 21G) and yellow (IG = 2IR). In this design, the anodes of the double LED driven by the outputs a six-point buffer tri-state technology CMOS. Unlike most integrated family of CMOS 4000, the 4503 used here, can provide a variety of loads on high currents of the order of 1O mA. The stream that goes to the two diodes is limited by the resistors R 1 to A6 whose specific values ??are those that achieve the different colors and changing brightness them. The circuit was originally designed to display three different situations, each expressed their the presence of logical '1 'in one of the inputs a, b, c. The entries are able to activate only one of each time, and if none of them were excited, a NAND gate (IC1c) made sure that the LED 'to produce fourth color. In the improved version we present today, the circuit has added another level oscillator (IC 1 a and IC1b), which produces about two pulses per second. The pulses are introduced at the entrance activation OA (pin 1) of 4503, resulting in colorful flashes. The oscillator is controlled by the of logical statements applied to the inputs 'd' and 'e'. If both are simultaneously logical '1 ', then both the oscillator and the buffers of 4503 remain inoperative. If e = O and d = 1, then all buffers are driven in a state of high resistance and the circuit absorbs the least possible current (standby). The power circuit was initially set at 12V, but all the components that are able to work equally well with any voltage between 5 and 16 V.

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