Build Your Own Class AB Audio Amplifier

[Dino Segovis] wrote in to tell us about his “hack”, making an AB Audio Amplifier. The advantage of this particular amp is that the transistors never turn off, which would cause distortion. A full schematic is given in the article as well as a parts list. A complete “bill of materials” makes any circuit building project easier, especially for the beginner.

Although this is by no means a new circuit design, (a similar setup is used in car audio equipment) [Dino] does a great job of explaining how things work in the article itself and in the video after the break. He also gives some great tips about transferring your drawn circuit to a breadboard in a neat and organized way at around 5:00 in the video. [Read more...]

Basic Animatronics Tutorial: PIC Based Servo Eyebrows

[Chris] writes in to let us know about his latest animatronics tutorial, this time on robotic eyebrows! The tutorial takes us through the process of using a fairly simple PIC  circuit to display various facial expressions. Since a wide array of facial expressions have unique and well understood eyebrow positions this simple hack can make even the most bland looking mask come to life . Animatronics is a subject near and dear to our hearts, but the simple actuation of servos can go much further than cardboard faces. This easy to follow tutorial can help you on your way to controlling all sorts of servo stuff like vent flaps or um…  fish, if you’d like. The software is not very deeply explained but it is commented and available for download from [Chris]‘s site.

From here [Chris] plans to expand the project with more tutorials that can help further animate the face. We are particularly interested in the one and two eye systems he mentions, as well as more complicated eyebrow mechanics. Also check out [Chris]‘s other servo based robotics tutorials like the Sharpie Spotifier and the Wooden Menace.

There is also a video of the eyebrows in action after the break.

[Read more...]

Understanding interrupts in PIC microcontrollers

Interrupts are the name of the game for more functional microcontroller firmware. [Rajendra] just posted a tutorial covering all of the interrupt types for the PIC 16F688 microcontroller. He gives an overview of all of the major points: what an interrupt is, what causes interrupts, how to read the datasheet (often overlooked) to set up interrupts, and finally he applies it to a test platform and a bit of code.

We’ve been playing around with an Arduino again over the weekend and are a bit frustrated with the restricted access to interrupts. That issue deals with AVR interrupts, a topic with which we’re already well acquainted. But we work with PIC hardware much less often and it’s fun to explore how the other half does things, both in hardware and in code.

Electronics tutorial two-fer: soldering skills and wires

electronics_tutorial_twofer_soldering_skills_and_wires

There is a plethora of electronics tutorials scattered about online. Sometimes it can be hard to separate the good ones from the bad, and the enlightening from the misinformed. We recently came across a pair that we found helpful, and thought they would appeal to anyone starting off in electronics.

In this video tutorial, [Dave Jones] at the EEVblog covers soldering, detailing good practices and common mistakes to avoid when working with through-hole components. As the second video in a series he picks up where part one left off, excitedly demonstrating the ins and outs of good soldering skills.

Hackaday reader [grenadier] is working on a series of beginner’s electronics tutorials, and this week’s entry covers wiring. He discusses wire types, gauges, and even provides a nifty self-computing chart that calculates power loss based on the length and gauge of the selected wire. Before wrapping things up, he briefly touches on fuses and the pitfalls of choosing wire that’s not up to the task at hand. While you’re over there looking over his tutorial, be sure to check out the Junkbox, there’s plenty of awesome stuff to be had!

Pulse Width Modulation with microcontrollers

Those following the ProtoStack tutorials will be happy to hear that there is a new installment which explains Pulse Width Modulation. If you’ve never heard of PWM before, it’s a method of generating a signal that is logic 1 for a portion of the time and logic 0 for the remainder of the time. It is the most commonly used method for dimming an LED, and that’s [Daniel's] example in this tutorial. But you’ll also find it used in many other applications such as servo motor control and piezo speaker control.

[Daniel] starts off with a brief explanation of duty cycle, then moves on to some examples of hardware and software PWM. Many of the AVR microcontrollers have a hardware PWM feature that allows you to configure a pin that toggles based on a target timer value. This is demonstrated using an ATmega168, but a method of using interrupts and your own code is also covered in case you don’t have a hardware PWM pin available.

A beginner’s guide to LED matrices

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[Rajendra Bhatt] wrote in to share a tutorial he put together demonstrating the basics of using LED dot matrix displays. While this subject might be old hat to many out there, his helpful walkthroughs are geared more towards beginners who are exploring various electronics concepts for the first time.

He explains the theory behind LED displays using a PIC-driven 5×7 matrix as an example. He discusses persistence of vision and how tricking the human eye can save you quite a bit of time and a whole lot of pins. Multiplexing is broken down into its most basic steps, which [Rajendra] illustrates by showing how a letter would be drawn on the LED display one column at a time. The use of a ULN2803A Darlington Array is also discussed, and he details why it is used when pulling the five columns of LEDs to ground.

The only portion of the tutorial we thought could be expanded upon was the programming section. While he does show how each letter of the alphabet can be displayed via a series of five hex values, he does not cover the “why” part of the process. Obviously while anyone familiar with binary and hex can figure it out in pretty short order, we think that it would be a great place to pause and expand the readers’ knowledge even more.

Overall it’s a useful tutorial, and most beginners would likely find it quite helpful.

Make presents: The Multimeter

This video falls under the category of things we want to send people when they ask “how do I get started with electronics”, and we get asked that a lot. For those of you who have been working with electronics for years at all, you can skip this entire video. That is, unless you really want to watch an instructional video on multimeters. In the video, which we’ve included after the break, they talk about the differences between different meters, the common uses and how to actually use the meter to get the results you need. Stuffed full of useful information, this video will get those of you who are still reading up to snuff pretty quickly. Now go use your multimeter to do some hacking!

[Read more...]

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