Before LM3915 bar graph drivers were common, Elektor showed you how to build a 10-LED meter using just op-amps and diodes. Building this will teach you more about comparators than any textbook.

Logic probes and active RF probes to troubleshoot complex circuits. 3. Power Supplies and Chargers

But is it still relevant in the age of Arduino and Raspberry Pi? Here is why.

The designs focus on efficiency, showing you how to solve complex hardware problems using cheap, readily available components. Modern Adaptations: Bringing 304 Circuits into the 2020s

If you want to dive deeper into a specific project from this era, tell me:

Do not rush to manufacture a custom Printed Circuit Board (PCB). Build the circuit on a breadboard first. This allows you to tweak resistor or capacitor values to customize the circuit's performance to your specific needs. How to Safely Locate the PDF Archive

Whether you are looking at a classic 555 timer application or a specific configuration of the TL071 op-amp, a PDF allows you to search keywords and find exactly what you need in seconds.

Used in dozens of configurations here, from astable multivibrators (clocks/pulse generators) to monostable timers.

Published as part of Elektor’s famous "300 Series" (which includes 301, 302, 303, 304, and up to 311 Circuits), the 304 Circuits edition is a curated compilation of blueprints originally featured in the magazine's annual summer double issues.