LCD-LED DisplayLights and Display Board Circuits

Programmable LED indicator Schematic Circuit Diagram

Understanding LED Indicators in Electronics

One of the most widely used current-w indicator in the field of electronics is undoubtedly the light-emitting diode (LED). These LEDs are available in an array of colors, including red, green, blue, yellow, and even dual colors. Additionally, they come in various shapes, such as round and square, with some models featuring flashing functionality.

Challenges and Abuses Faced by LEDs

Despite their durability, these LEDs are often subjected to various forms of misuse and abuse. Common issues include excessively short terminals, excessively high current, and damage caused by a soldering iron, among others. To address these concerns, the circuit described in this context provides a solution. This circuit allows for the LED indication to be customized based on the specific requirements of the circuit being worked on. Users can adapt the LED indication to their preferences, choosing between flashing or non-flashing modes and selecting colors like red or green, among others.

Programmable LED indicator Schematic diagram

Dual-Color LED Indicator Circuit

At the core of this indicator circuit lies a dual-color diode, D2. The way this diode illuminates upon activation of the indicator input depends on the configurations of switches S1-1-3. Switch S1-4 facilitates the adjustment of the high or low level to which the input responds. Components R9, D3, and D4 serve as safeguards, protecting the input from potential damage in case the input voltage rises excessively.

Oscillator and LED Control

An oscillator, created by IC1a and IC1b, generates a flashing frequency that is regulated by R31. Based on the positions of switches S1-1-3, the oscillator signal is applied to the dual-color LED through multiplexer IC2 in a specific manner. For user convenience, the actions of switches S1-1-3 and their corresponding LED behaviors are summarized in Table 1. Similarly, the positions of switch S1-4 and the resulting LED status are outlined in Table 2. The indicator circuit requires a power supply ranging from 8 to 25 V, drawing a current of 30 mA in normal operation at 25 V.


Programmable LED indicator Schematic diagram

Programmable LED indicator Schematic diagram

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