How to replace an 8051 by an AVR...

To update the software of a vintage microcontroller system you can simply replace the whole system or try to modify it. Replacing often means throwing away parts that work perfectly fine, which some people find hard to accept. If the old hardware is based on the venerable 8051 microcontroller then here's a way to replace it by a modern AVR micro while keeping all the rest. Immediate access to the wonderful world of Arduino is thrown in for free.

The simplest lab power supplies have an adjustable output voltage and (ideally) short-circuit protection, which is sufficient for an electronics enthusiast to get started. The better models also have adjustable output current limiting, and precise indication of the output voltage and current is a feature that should be present in any respectable lab power supply. This circuits adds another nice feature: a soft start.

Even though using the sun to recharge one or more batteries is nothing new, a simple circuit that can be put together quickly on a rainy afternoon always comes in handy. Here is such a circuit. It uses a little ATtiny13 microcontroller to keep things under control.

Invented about one hundred years ago the Theremin remains a popular electronic musical instrument. Commercially available high-quality designs are expensive making DIY projects extra appealing. However, it is not so easy to come up with a reproducible all-analogue circuit. Can you help?

The Joule Thief is a simple circuit that lets you use almost all the energy stored in a single-cell battery. Because it is so simple a lot of people like to play with the circuit. According to Wikipedia the idea dates back to almost a century now. Here is a complicated variant that doubles as a transistor thief. (Read the comments.)

With a Raspberry Pi, a touch screen and “some” extra effort like developing a high-voltage power supply, writing a graphical interface, and tooling metal you can come up with great results like this high-voltage curve tracer…

The Internet has loads of information on the past, from prehistoric to recent, yet I do not know of a system or tool capable of compiling all this information into a virtual reality like Google Street View, that lets the user stroll around in the past. I'd like to enter a date & place and get a feel of what things looked and were at that specific time, not just by watching a few photographs, but by actually walking around. Can you help me?

“James, one Martini please -- shaken, not stirred.” This project allows you to ask your personal assistant to prepare your favourite cocktail whenever you feel like it. When the cocktail is ready all you have to do is walk over to the machine and pick it up. You can easily understand why this project won the 2018 ESP32 Design Contest.

The winners of the Elektor ESP32 Design Contest 2018 are known! After many hours of wading through project descriptions, watching videos and reading source code, the top 10 of the best projects has been established. What a difficult task it was for the jury with so many high-quality projects contesting for the fantastic prizes. And the Grand Prize has been awarded to...

Besides small SUVs, crossovers are also filters used in audio to divide the audio signal into two or more frequency bands. A typical example is a home cinema audio system where a subwoofer handles the low bass frequencies while other speakers handle the mid and high frequencies. Here is an active 3-way crossover design with three or four stages based on state-variable filters.