How to test crystal oscillators

This post is about a simple circuit to test crystal oscillators . They are found in most of the RF and processing circuitry as an external component to provide clocking, time reference for synchronization of internal system operations. testing them isn't that straight forward by connecting its terminals to a multimeter or an oscilloscope. This is an interesting test circuit for crystals in 1MHz - 30MHz range with 2 NPN transistors, Zeners, some passives, and thought of testing a few crystals.
When the DUT crystal oscillates, the signal passes through the 1nF loading capacitor to the two Zeners, thereby charging the 4.7nF capacitor and turns on the second transistor which in turn illuminates the LED, indicating that it's all good!

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Building a Robot Actuator with ESP32 and a 5010 BLDC Motor

Introduction Modern robotics demands actuators that aren’t just strong, but also smart — capable of precise control, smooth motion, and safe human interaction. Traditional servos are great for small robots, but they can be stiff, noisy, and limited in range or torque. This project demonstrates a custom robot actuator built around a 5010 360 KV brushless DC (BLDC) motor , controlled by an ESP32 running the SimpleFOC library. The goal is to create a compliant joint — one that can be moved by hand, but automatically returns to its home position with adaptive stiffness. 🧠 What Makes This Actuator Special Unlike a typical servo, this actuator behaves intelligently : You can turn it by hand — it feels soft and back-drivable. When you release it, the motor returns to its initial position smoothly. If you twist it harder (e.g., due to gear reduction), it becomes stiffer , resisting displacement more strongly. It’s powered by 12 V and controlled by a simple ESP32 boar...

How to Play a Sound After a Terminal Command Completes

Sometimes, while working on the terminal, especially during long-running processes, it’s useful to have an audible notification when the task is finished. In this guide, we’ll show you how to make your terminal play a sound after any command completes, ensuring you're alerted without constantly checking the terminal. Why Do This? This trick can save time and improve workflow, especially when: You’re running lengthy build processes or installations. You’re waiting for large file transfers. You're programming embedded systems and need confirmation when flashing is done. Let’s dive into how to do this on a Linux system. Step-by-Step Guide to Playing a Sound After a Command 1. Using paplay or aplay to Play Sounds On most Linux distributions, you can use paplay or aplay to play sound files directly from the terminal. Here's how you can append a sound notification after a command. Basic Command Structure : PC:~$ your_command && paplay /path/to/soundfile.oga Or, if...

How to Automatically Change Citation Color in Word (e.g., Blue) Using Zotero + Macro

Hi everyone 👋 I’ll be honest upfront: I’m not a huge fan of Microsoft Word — I usually work in LaTeX , where formatting and citations behave exactly the way I want without any hacks 😄 That said, we all occasionally find ourselves back in Word , whether for collaborations, journal templates, or institutional requirements. And when that happens, a few quirky tricks can go a long way. If you’re using Zotero with Microsoft Word and want to improve the visual style of your document, this small trick can be surprisingly useful. In many scientific papers and technical documents, in-text citations appear in blue , similar to hyperlinks. Unfortunately, Zotero does not provide a built-in option to automatically change citation colors in Word. The good news? You can achieve this easily using a simple Word VBA macro no need to abandon Zotero or manually format citations one by one. i originally found this in zotero forms this > Post < Below is a simple,...

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