Author Archives: DP

DIY long lasting voltage regulator circuit for Raspberry Pi

via Dangerous Prototypes

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

via Dangerous Prototypes

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

via Dangerous Prototypes

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.

App note: Grounding techniques

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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

via Dangerous Prototypes

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

via Dangerous Prototypes

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.