The HC-SR04 proximity sensor is an inexpensive and widely-used ultrasonic device. Connecting one to an HC-SR04 to a Raspberry Pi is a common educational exercise, but getting accurate, repeatable measurement of distance in a real application is actually quite difficult. This article explains why, and what can be...

A simple and inexpensive shift register can be used to increase the digital output provision of a Raspberry Pi or microcontroller. This well-know technique is easy to apply, but has some limitations that require careful consideration.

Misrepresentations of scale are common in the literature of organizations that seek to deceive. However, it's sometimes difficult, or unhelpful, to draw diagrams to scale. This article tries to explain the difference between benign and pernicious distortions of scale. I'm picking on the flat-earthers for the...

It's common for hifi amplifiers and speakers to have a power rating expressed in terms of "RMS watts". Although RMS amplitude is an important concept in electronic engineering, it's meaningless here, and should be avoided.

The calculus of variations is a branch of mathematics that deals with finding functions that optimize systems. Although calculus of variations has its origins in the 18th century, it is still not widely taught, either to science or engineering students. This brief guide intends to explain the basic principles, with...

Many portable and automotive media players accept USB memory sticks or SD cards containing audio files. Very often, these players have no sorting logic, and display files and directories in the arbitrary order they appear in the filesystem. This article describes how to sort a FAT filesystem using Linux utilities,...

A number of reviews of the Leak Stereo 130 and CDT can be found online, but they are short on practical details. I've been using mine eight hours a day for several months; this is what I think of them.

Why are sales of vinyl records increasing, when digital streaming services provide access to almost any recording ever made, in superior technical quality?

Copying an audio CD -- perhaps to a portable music player -- is a common enough operation. There are strong opinions on how to do this, and what software to use. But does it really make any difference? Or is one bit the same as any other?

The availability of "better than CD" audio recordings is driving, and being driven by, more expensive and elaborate audio hardware, even in the consumer market. Is this a good thing?

You really can't improve your hi-fi system with a fancy mains cable. But why? And why do people think you can?

Bits are bits, right? If a CD transport just sends digital data to a DAC, is it even possible that different transports sound different?