App note: Cable compensation of a primary-side-regulation power supply

Another tech note from Richtek on power supply regulation with cable compensation. Link here

Cable compensation has been used to compensate the voltage drop due to cable impedance for providing a regulated charging voltage in battery charger applications. This application note uses a novel cable compensation method, which called cable minus compensation, as an example to describe the concept and design criteria for the cable compensation of a PSR flyback converter. The analytic results are also verified by the simulation results.

App note: Analysis of buck converter efficiency

Tech note from Richtek on buck converter profiling. Link here

The synchronous buck circuit is wildly used to provide non-isolated power for low voltage and high current supply to system chip. To realize the power loss of synchronous buck converter and to improve efficiency is important for power designer. The application note introduces the analysis of buck converter efficiency and realizes major power component loss in synchronous buck converter.

The ArduINA226 power monitor

ArduPicLab published the details on how to build a current, voltage and power datalogger with Arduino and the INA226 module:

In the past I have developed various projects of ammeters based on Hall effect current sensors such as the ACS712, or on High-Side Current-Sense Amplifiers such as the MAX4080SASA or made with operational amplifiers. All these systems have an analog output which must then be digitized. The INA226 sensor has a digital output and incorporates a 16-bit ADC for which a high accuracy and precision is obtained.

MCP4141 based digital potentiometer

Dilshan Jayakody has been working on an open-source hardware project MCP4141 based digital potentiometer, that is available on GitHub:

The main objective of this project is to create an experimental prototype of a digital potentiometer using Microchip’s MCP4141 IC. MCP4141 is available with end-to-end resistances of 5KΩ, 10KΩ, 50kΩ, and 100KΩ. This potentiometer-module can drive MCP4141 with any of the above mention resistances.

DIY motion simulator

Bogdan Berg has been working on a DIY motion simulator:

As you may have seen from some of my other posts on this blog, motorsports and cars in general are one of my passions. I try to attend at least couple track days in a season, and enjoy circuit racing greatly. However, costs can add up quickly, and living in Seattle leaves us with a lot of rainy days through fall/winter/spring, somewhat limiting the time window for optimal conditions on the track. Although racing in rain as an art in itself… 😉

See the full post at

Check out the video after the break.

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Inside a Titan missile guidance computer

Ken Shirriff has written an excellent in-depth look at a Titan missile guidance computer:

I’ve been studying the guidance computer from a Titan II nuclear missile. This compact computer was used in the 1970s to guide a Titan II nuclear missile towards its target or send a Titan IIIC rocket into the proper orbit. The computer worked in conjunction with an Inertial Measurement Unit (IMU), a system of gyroscopes and accelerometers that tracked the rocket’s position and velocity.

See the full post at

DIY long lasting voltage regulator circuit for Raspberry Pi

Jithin @ writes:

Raspberry Pi is simple, handy and cheap yet powerful single board computers of all time. It has USB ports to connect hardware such as pen drive, keyboard, mouse, HDMI port for display out, 3.5 mm port for audio and several GPIO pins to work with embedded projects, all of which can be powered using a mobile charger. You can even make it portable by simply connecting the mini USB port to a mobile phone power bank so that you can use your pi on the go. But if you connect more USB devices and use the GPIO pins, the power bank will drain off quickly. In this post, I will tell you how i made my own power supply unit using a Lithium Polymer battery and a voltage regulator.

Project info at

Building my own 50Ah LiFePO4 lithium battery pack

Kenneth Finnegan posted his DIY 50Ah LiFePO4 lithium battery pack build:

Several years ago, I had purchased a 20Ah 12V Lithium Iron battery pack from Bioenno for my various 12VDC projects. To help protect it, I ultimately built it up into a 50cal ammo can with a dual panel-mount PowerPole connector on the outside, which has proven really nice as far as battery boxes go:
*20Ah is a decent battery capacity for a small load
*The packaged Bioenno pack left some space inside the box to also store the charger it came with, some PowerPole accessories, etc
*The fact that you’re able to close up the box and use the power connectors on the outside once you’re using it is real nice

More details on The life of Kenneth blog.

Low cost open source ventilator

Johnny Chung Lee writes, “In the event that COVID-19 hospitalizations exhaust the availability of FDA approved ventilators. I started documenting a a process of converting a low-cost CPAP (Continuous Positive Airway Pressure) blower into a rudimentary Ventilator that could help with breathing during an acute respiratory attack. If interested, follow along the Github Project

More details on Procrastineering blog.

Looking inside a vintage Soviet TTL logic integrated circuit

Ken Shirriff examines a 1980s chip used in a Soyuz space clock:

The clock is built from TTL integrated circuits, a type of digital logic that was popular in the 1970s through the 1990s because it was reliable, inexpensive, and easy to use. (If you’ve done hobbyist digital electronics, you probably know the 7400-series of TTL chips.) A basic TTL chip contained just a few logic gates, such as 4 NAND gates or 6 inverters, while a more complex TTL chip implemented a functional unit such as a 4-bit counter. Eventually, TTL lost out to CMOS chips (the chips in modern computers), which use much less power and are much denser.

More details on Ken Shirriff’s blog.

App note: Nonideality of ground

Ground in PCB design, another app note about grounds from Renesas. Link here (PDF)

Ground is supposed to be ideal. It should be a black hole for stray currents where the voltage is always zero. Unfortunately, those stray currents travel through some non-superconducting material, so small voltages arise. You may not notice small changes in ground potential, you may, instead, notice surplus noise or instability or other unwanted attributes in your system. We are going to discuss ground. Every circuit is unique and grounding paths are different for every device on your board and in your system. Therefore, we are starting with an intuitive approach to try and give you a feel for the paths currents choose to travel and how that affects the ideal assumption of ground being zero volts.

App note: Grounding techniques

Renesas detailed app note about grounds. Link here (PDF)

Ground is taken for granted. We stand on it, we dig into it, we make mud pies out of it. The ground isn’t supposed to move. We don’t have to think about it; it just is. When it comes to grounding a circuit, we assume that our connections are as solid as the turf below our scuffed shoes. Many times, this is a reasonable assumption-but not always. How do we know when there is a problem with a circuit’s ground? What practices will ensure we construct a good ground?

No longer to be taken for granted, we define ground in ideal and real situations. Ground configurations and printed circuit board (PCB) examples will be presented.

AVR high voltage programmer 2

Dilshan Jayakody posted an update on his AVR high voltage programmer project we covered previously:

AVR-HV2 is Arduino based high voltage parallel programmer for AVR microcontrollers. This programmer can read, write, and erase both flash memory and EEPROM. Also, this can use to set fuse bits of AVR MCUs. Compare with the previous version of AVR HVPP, this design is based on commonly available components with a simple schematic. In this release driver software is also rewritten to provide cross-platform support.

More details on Dilshan Jayakody’s blog. The design files are available on GitHub.

Rothko clock Nixie shield with 6 IN-17 tubes

Florinc writes:

This Nixie shield was designed by Tyler around 2013, as an open source project. A little after the successful kickstarter campaign, it just disappeared. I was one of the backers and I received a couple of PCBs for my contribution. I used them to built clocks and I even wrote some review blog posts. I also re-designed the PCB from a simplified schematic (so this is a little bit different than the original).
This is the smallest Arduino Nixie shield out there that has 6 Nixie tubes on the same board (together with the high voltage supply and the tube drivers).

See the full post on Wise time with Arduino blog.

Cassette Pi IoT scroller

The Cassette Pi IoT scroller project @

The Cassette Pi is a self-contained real-time notification scroller, all housed neatly inside a transparent cassette tape. A Raspberry Pi Zero is sandwiched between the two tape reels, retrieving Internet of Things notifications from the fabulous IFTTT service, delivered almost instantly to the Pi via an Adafruit.IO feed and a Python script. The whole cassette vibrates to alert you to the incoming notification, and the text is then scrolled clearly across a Pimoroni 11×7 LED display.

More details on Hackster and Instructables, and the code is on GitHub.

Check out the video after the break.

Continue reading “Cassette Pi IoT scroller”

Making an OBD-II solar trickle charger

Kerry Wong shows how to make a simple solar trickle charger:

On a few occasions my car struggled to start when I returned from my business trip and I had to charge the battery manually later on by hooking up a charger, which was quite inconvenient. So I decided to make a simple solar trickle charger that can be left inside the vehicle and charge the battery while the car is parked.

More details on Kerry Wong’s blog.

Check out the video after the break.

Continue reading “Making an OBD-II solar trickle charger”

App note: DC-to-DC design guide

DC-DC converter design guide from Vishay. Link here (PDF)

Manufacturers of electronic systems that require power conversion are faced with the need for higher-density dc-to-dc converters that perform more efficiently, within a smaller footprint, and at lower cost despite increasing output loads. To meet these demands, Siliconix has combined advanced TrenchFET and PWM-optimized process technologies, along with innovative new packages, to provide:
– lowest on-resistance for minimum power dissipation
– lowest gate charge for minimum switching losses
– dV/dt shoot-through immunity
– improved thermal management

App note: Torque recommendations for TO-220 devices

App note from Vishay on the impact of torque on thermal resistance of TO-220 devices. Link here (PDF)

When the TO-220 was first introduced, most applications required something less than the full power handling capabilities of this package. Hence, the TO-220 is almost taken for granted in terms of its excellent power handling capacity and ruggedness. Today, however, advances in semiconductor technologies are bringing application demands closer to the TO-220’s capabilities, so an understanding of these is more relevant than ever.

DIY 18650 Powerwall with onboard BMS

A DIY 18650 Powerwall with onboard BMS @

While I cannot afford a Tesla PowerWall, I’ve spent some time drawing up a PCB to house 7x 18650 cells in series. Each board has onboard Battery Management:
*Overvoltage Protection (per cell)
*Undervoltage Protection (per cell)
*Balance Charging
*Overcurrent Protection
*Main pack Fuse

The design files are available on GitHub.

The core memory inside a Saturn V rocket’s computer

A closer look at an LVDC core memory module:

The Launch Vehicle Digital Computer (LVDC) had a key role in the Apollo Moon mission, guiding and controlling the Saturn V rocket. Like most computers of the era, it used core memory, storing data in tiny magnetic cores. In this article, I take a close look at an LVDC core memory module from Steve Jurvetson’s collection. This memory module was technologically advanced for the mid-1960s, using surface-mount components, hybrid modules, and flexible connectors that made it an order of magnitude smaller and lighter than mainframe core memories.2 Even so, this memory stored just 4096 words of 26 bits.

See the full post on Ken Shirriff’s blog.