Posts tagged LEDs
Arduino Optical Fingerprint Sensor (AS608)

Optical fingerprint sensors take low-resolution snapshots of the tip of a finger and create arrays of identifiers that are then used to uniquely identify a given fingerprint. The AS608 is capable of storing up to 128 individual fingerprints. This tutorial will introduce the AS608 Arduino-compatible fingerprint sensor and how to validate and reject fingerprints based on the enrolled fingerprint information that will be given to the sensor. The fingerprint algorithm is handled by the AS608 and Arduino, so this tutorial will focus on implementation and putting the pieces together to make a working fingerprint sensor with Arduino.

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Controlling LEDs with A Multiplexer and Arduino

A demultiplexer will be used to control 8 LEDs using just 3 digital pins on the Arduino board. This method of demultiplexing frees up pins on the Arduino, but also makes control of multiple LEDs easier by consolidating the power given to each LED. This will allow us to use LEDs without resistors. In general, a demultiplexer uses N boolean outputs to control 2N switches. In our case, the CD4051 multiplexer will be used as a demultiplexer using 3 digital pins and boolean logic to control 8 individual LEDs. Several skills will also be developed, specifically with regard to programming in the Arduino programming language. Pulse-width modulation (or brightening and dimming) of LEDs will be explored, as well as randomization of LED blinks, along with the general selection process for boolean switching with the demultiplexer.

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A Guide to Metal Core PCBs by PCBGOGO

The use of LED based electronics has significantly increased in the past few years. They have proven to be more efficient and nearly 5 times cheaper than normal incandescent units. But with their use came one downside: heat. Some devices tend to use a number of LEDs that remain on for a long period of time and so can overheat. The LEDs are usually mounted on PCBs and can therefore cause significant damage. There is however one alternative to common PCBs i.e. metal core printed circuits (MCPCBs).

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Arduino SoftPot LED Meter (Membrane Potentiometer)

How to use a soft, circular-membrane potentiometer with an Arduino board. Potentiometers function by altering the voltage of a system by mechanically changing the resistance associated with a voltage divider. In a traditional potentiometer (think of turning a volume knob), we are physically changing the voltage of a system. In the case of a soft potentiometer (where the name SoftPot comes from), we are altering the resistance of the voltage divider by physically depressing the potentiometer, thereby changing the resistance at a contact point. The working principle is exactly the same, but in the SoftPot’s case, we are pressing, and for a knob we are rotating.

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