Engineering in August: 8-Bit Arduino Sounds, a Simple Hybrid Amp, and More

Engineering in August: Arduino 8-bit sounds, a simple hybrid amplifier, and more

With the summer coming to an end, now is the time to take a look at some of the most iconic articles and engineering projects from the previous August issues of Elektor. Check out the following summaries and tell us what you think.

With the summer coming to an end, now is the time to take a look at some of the most iconic articles and engineering projects from the previous August issues of Elektor. Check out the following summaries and tell us what you think.

MIDI I/O Breakout Board (August 2019)

In the summer of 2019, after more than 35 years of standardizing MIDI, Clemens Valens introduced our readers to MIDI 2.0 and its new features, including two new connectors.

He wrote: “The new MIDI Breakout Board (BoB) that we offer here can be equipped with one of three connector types: DIN, TRS-3.5 or TRS-2.5.” Furthermore, the BoB supports RF grounding and 3.3V signaling, and the same PCB can be configured as either MIDI In or MIDI Out (or MIDI Thru, which is the same as Out).

Then it goes on to cover ground loops against EMC and MIDI in optocoupler calls, low voltage signal calculations, and more. Check out the article and dive deeper into the engineering.

Arduino on Course: Welcome & Arduino 8-bit Sound Generation (August 2012)

Elektor readers and engineers have been Arduino enthusiasts since the beginning. In the summer of 2012, the popular series “Arduino on Course” began with David Quarteles, co-founder of Arduino. The first article in the series presents everything you need to understand to power 1-bit audio from a digital pin on an Arduino board.

Arduino with Piezo - August Engineering

“We’ll start by looking at the easiest way to create sound with a simple piezo bell or speaker,” he explained. “I will then present an Arduino tone library, as a simplified way to achieve the same functionality. I will conclude by presenting an advanced technology that allows playback of short sounds stored in the form of .wav files. When it comes to theory, you will be introduced to a technique known as 1-bit Delta Sigma digital-to-analog conversion, but Don’t be afraid of the name, methods and techniques are given along with examples that you can easily reproduce with a small set of parts.”

Simple Hybrid Amplifier (August 2006)

Which is better – valves or transistors? Elektor author Frans Janssens asked this question back in 2006. It didn’t answer the question (leaving that up to you), but it went on to provide an interesting design. Its simple hybrid amplifier uses a “valve as the pre-amplifier and a MOSFET in the output stage. The strong negative feedback makes the frequency response flat as pie”.

Simple Hybrid Amplifier - August Engineering

Design features and specifications include: minimum gain = 12.3 x, maximum gain = 31.6 x, input sensitivity = 0.64 V at minimum gain, bandwidth = greater than 200 kHz, and low frequency inversion = 11 Hz.

Hygrometer (August 1997)

Do you need a hygrometer? If so, why buy when you can build? In 1997 we introduced a simple design for a device to measure – or generate an output signal proportional to – the ambient humidity. The design was suitable for operating a ventilator or dehumidifier in places such as the bathroom or kitchen where at certain times humidity can reach uncomfortable or unacceptable levels.

humidity schematic

“Usually, hygrometers use a humidity sensor; but the current circuit uses a capacitor whose capacitance depends on the degree of humidity.”

Car Battery Monitor (August 1991)

Before cars had hundreds of MCUs and sensors that monitored everything from temperature to tire pressure, engineers had to create their own DIY solutions. In 1991, Elektor featured a car battery monitor design that enabled drivers to monitor battery status using just a few LED lights.

car battery monitoring

Two LED lights installed inside the vehicle indicate whether the battery is charged or discharged with a large current, providing a reassuring check of alternator function. A third LED is provided to indicate a nice neutral area in which the battery is only lightly charging or discharging.”

Car Radio Alarm (August 1986)

In the summer of 1986, car radio theft was apparently widespread enough for an Elektor community member to design an alarm for his car. “The purpose of this single-chip circuit is to give an audible alarm in the event that a thief attempts to steal a car radio, which is generally considered to be an item of paramount importance to the driver’s well-being during any journey with his vehicle.”

car radio alarm

If someone tries to steal the car radio, the system will sound the horn for 30 seconds, which should be enough time to scare off the thief.

Engineering continues

In September, we will highlight more classic elector Articles, projects and tutorials. If you have any ideas, questions or feedback, please share your thoughts in the comments section below. Engineering never stops!

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