Silicon die analysis: Inside an op amp with interesting “butterfly” transistors


An excellent in-depth look at theTL084 op amp by Ken Shirriff:

Some integrated circuits have very interesting dies under a microscope, like the chip below with designs that look kind of like butterflies. These patterns are special JFET input transistors that improved the chip’s performance. This chip is a Texas Instruments TL084 quad op amp and the symmetry of the four op amps is visible in the photo. (You can also see four big irregular rectangular regions; these are capacitors to stabilize the op amps.) In this article, I describe these components and the other circuitry in the chip and explain how it works. This article also includes an interactive chip explorer that shows each schematic component on the die and explains what it does.

See the full post on Ken Shirriff’s blog.

DIY Arduino FM radio


Nick over at shared detailed instructions of how to build this DIY Art Deco style FM Radio project using Arduino:

Let’s see what we are going to build today! As you can see, we are going to build an Art Deco style FM radio receiver. The design of this radio is based on this spectacular 1935 AWA radio. I discovered this old radio while searching online and also in this book about the most beautiful radios ever made. I loved the design of this radio so much that I wanted to have a similar one. So I devoted a month of my time to build my own.

Full details at

Check out the video after the break.

App note: Capacitive sensing: Direct vs remote liquid-level sensing performance analysis


Capacitive liquid level sensing method comparison discussed in this app note from Texas Instruments. Link here (PDF)

Capacitive-based liquid level sensing is making its way into the consumer, industrial, and automotive markets due to its system sensitivity, flexibility, and low cost. With using TI’s capacitive sensing technology, the system flexibility allows designers to have the choice of placing the sensors directly on the container (direct sensing) or in close proximity to the container (remote sensing). Each configuration has its own advantages and disadvantages. This application note highlights the system differences and performance of direct and remote sensing to provide guidance in how capacitive-based liquid-level sensing is affected.

App note: Measuring liquid levels using hall effect sensors


App note from Infineon on methods used in liquid level measurement and how contactless hall effect sensors are the right choice for the job. Link here (PDF)

This application note is dedicated to liquid level sensing using non-contacting magnetic sensor technology. First, an overview of some liquid level sensor application requirements are given. Next, we will introduce some of the solutions that are employed today and are researched for future systems, including both contacting techniques as well as non-contacting methods. Magnetic sensing turns out to be a comparably easy and robust solution to tackle the problem and Infineon’s linear Hall sensor portfolio is presented. Different design aspects of a magnetic liquid level sensor, including magnetic circuit designs, are discussed. The last section introduces some of Infineon’s Hall effect sensors that are suitable for use in fuel level sensing.

3D printed stirling engine gas burner and flywheel

Stirling Engine

The 3D printed Stirling Engine with its new gas burner and heavier flywheel from Do It Yourself Gadgets:

Take a look at my upgraded Stirling Engine with its new gas burner and flywheel!
If you take a look at my previous post you’ll see how I built a 3D printed holder for my Stirling Engine kit. Since I needed a constant heat source I added a small gas burner salvaged from an old BBQ lighter and attached it to the engine.

See the full post on Do It Yourself Gadgets blog.

Check out the video after the break.

LoraDunchy Arduino Nano pin-compatibile LoRa module with power management


Mare writes:

Lora board with Arduino nano compatibile pinout and simple battery management
Small board with arduino nano compatibile pinout with power management and Murata ABZ LoRa module with STM32L0 microcontroller
-LoRa module: Murata ABZ
-Single cell LiPo cell charger on-board with charging signal internally connected to PA11 (via jumper)
-Buck/Boost switching power supply for delivering stable 3,3V regardless of the batterz voltage
-Battery fuel gauge on-board to control the real status of the battery

See the full post on Mare & Gal Electronics blog and the GitHub repository here.

A touch numeric keyboard for Arduino or Teensy


Giovanni Carrera blogged about his touch numeric keyboard for Arduino or Teensy:

Very often, for our programs, we need a system to set parameters, usually of a numerical type. A 4×4 keyboard requires some space and then we also need a display. Here is the idea of using a touchscreen display to do both. I have then written the GetNum function that allows you to print a prompt message and to type an integer number. To test this function I wrote a simple analog data logger program that required two parameters, the first is the sampling period and the second the number of samples. In this example the number of channels to be scanned is set to three, but the program can be modified to request a third parameter with the number of channels.

See the full post on ArduPicLab blog.

Ethernet Relay board


Boris Landoni from Open Electronics writes about a new open source project Ethernet Relay board:

The project we are introducing in this article wants on to take on that task by creating, through dedicated connections, the possibility to remotely control your entrance gate, your fish tank, the garden lights, the watering system and so on, using numerous examples. It is an ethernet-controlled relay board, which can be used as an actuator to directly control 220 V loads, to command 0V ÷ 5V digital signals or to read the status of digital or analog inputs; everything can be done remotely by using an Internet capable LAN.

Full details at

EEPROM rotation for ESP8266 and ESP32


Xose Pérez over at Tinkerman writes:

The Arduino Core for ESP8266 and ESP32 uses one SPI flash memory sector to emulate an EEPROM. When you initialize the EEPROM object (calling begin) it reads the contents of the sector into a memory buffer. Reading a writing is done over that in-memory buffer. Whenever you call commit it write the contents back to the flash sector.
Due to the nature of this flash memory (NOR) a full sector erase must be done prior to write any new data. If a power failure (intended or not) happens during this process the sector data is lost.
Also, writing data to a NOR memory can be done byte by byte but only to change a 1 to a 0. The only way to turn 0s to 1s is to perform a sector erase which turns all memory positions in that sector to 1. But sector erasing must be done in full sectors, thus wearing out the flash memory faster.

How can we overcome these problems?

Full details at