Electronics – Quad Me Up

Ohm’s Law for beginners

November 14, 2019November 14, 2019 Leave a comment

Yes, Ohm's Law for beginners, not for dummies. I do not want to offend anyone and if you are interested in things like Ohm's Law, you are clearly not a dummy.

In this video, we will talk briefly about what Ohm's Law is and how it influences everything connected with electricity. That it describes the relationship between voltage and current. That when you increase the voltage, you increase the current as well. And that voltage and current combined together give you power! And that doubling the volatge, you increase the power 4 times!

Low Pass Filter Experiments

June 13, 2019January 19, 2020 Leave a comment

All flight controllers we use in RC hobby (FlightOne, Betaflight, INAV, Pixhawk, dRonin, and all the other) use low pass filters. What does a low pass filter do? It passes low-frequency components of a signal (below cutoff frequency) but attenuates high-frequency signal components (above the cutoff frequency).

Since it’s hard to make a visualization of this process with a software LPF filter, let’s make an analog equivalent using a resistor and capacitor and connect all of that to signal generator and oscilloscope.

Impedance Matching 101

May 31, 2019January 19, 2020 Leave a comment

Why do we match the impendance? And what the heck the impedance really is? 50Ohm, 75Ohm, low impedance, high impedance, reflections and all that crap that normal people usually ignore. Nobody said that we are “normal” over here so let’s take a look at this whole input/output impedance matching business.

ESP32 and GPS with a help of TinyGPS++ library

August 31, 2018August 31, 2018 1 Comment

One of the first projects I did with ESP32 development boards is a simple GPS tracker. OK, it's not really a tracker since it does not store the position anywhere, more like distance meter with a UBLOX Neo-8M Beitian BN-880 GPS unit and small SSD1306 OLED display.

This ESP32 GPS Thingy as I call it uses one button to store current position and then report straight line distance, speed and altitude compared to "Home Point". GPS communication is handled by TinyGPS++ library.

Oh, one the best things about ESP32 is that you can map ports to almost any pin you want. It's not like on ATmega328 where UART and I2C are always the same pins. Here you can choose them. How nice is that?

Code is available on GitHub.

Getting started with ESP32 development boards and Arduino

August 30, 2018August 30, 2018 3 Comments

However fond of good old Arduinos based on ATmega328 and ATmega32u4 we might be, no one can now say they are state of the art. Sure, they might be the first choice to do something cheap and simple, but compared to most more modern designs, they are just too old and too weak. Slow, little flash memory, little RAM, no built-in connectivity: no Bluetooth or WiFi.

When a few years ago ESP8266 started to appear, everything changed. The tinkers finally got something small and cheap with WiFi. And then, the world has changed, since ESP32 it the market.

Soldering, rosin, flux and a Stannol x32-10i flux pen

July 19, 2018January 20, 2020 Leave a comment

If you really really want, you can solder without flux. But it is a painful experience. Almost all modern solders have flux integrated into its core. And as long as you do not try to solder anything big, it’s enough. Of course, sometimes it is not enough and you have to help yourself with additional flux.

My favorite solution lately is a flux pen. Like Stannol x32-10i

CC1101 868MHz Wireless Transciever Pinout

December 16, 2017January 19, 2020 Leave a comment

CC1101 is another example of modern radio modules. I might not have the receiver sensitivity or LoRa SX1276, but with proper antennas should give more than 1 km of radio transmission. Recently I got a couple of them, so expect some new projects with CC1101 and Arduino.

Now, something that took me some time to find out, so you will not have to: CC1101 pinout:

Arduino hygrometer with DHT11 and SSD1306 OLED display

December 3, 2017January 20, 2020 Leave a comment

One of the things I like about Arduino ecosystem is that you can prototype pretty decent device in very short time. It might not be pretty, but will work. Just like my DIY hygrometer built with DHT11 and SS1306 OLED display I’ve built few weeks ago:

Simple, efficient and runs on 4 AA batteries. The best part is that it can be powered all the time. Arduino does humidity measurement, display the result and then powers itself down to conserve power. Cool, right?

Code is available in GitHub repository.

Crossbow LRS, hardware

November 19, 2017August 17, 2018 2 Comments

Weather outside is bitchy. Period. It rains, then it's windy and then maybe there is some direct sunlight for 15 minutes. No way to fly or test my DIY RC radio link.

But, there is some progress after all. My latest changes seems to be working just fine. On a bench link was stable for almost 3 hours. Later I too it for a standard range test: 2.8km LOS. It also worked, I still had around 5dB of link budget left on a ground level.

Back to the topic. Crossbow LRS is open source and open hardware. Maybe open hardware is too much, since there is almost no hardware to build. After all, first iteration is based on LoRa32u4 II development boards and running good old Arduino.

RX module requires no additional hardware:

TX module is slightly more complex. It required voltage stabilizer and inverter/level shifter made with single 2N7000 FET transistor. I2C OLED display is an option:

Hands on: LoRa32u4 II 868MHz LoRa development board

November 1, 2017August 17, 2018 4 Comments

Idea for Crossbow, DIY LRS system did not appearned in my mind out of nowhere. All my previous LoRa attempts were aimed at telemetry purposes only. E45-TTL-100 are cool, but bulky. If I would want to use them, I would either have to attach Arduino to it or hack it open and reprogram onboard CPU (like Qczek LRS does). Somehow it was not something what suited me very much.

But then I came across Adafruit Feather LoRa32u4 RFM95. Awesome idea. ATmega32u4 and HopeRF RFM95 LoRa module on one PCB, Arduino compatible, reasonably small and light. As a bonus, can be LiPo battery operated and has own 1S LiPo chanrger. The only thing I did not liked (OK, not the only one, but that was the biggest one) was price tag: $34.95 is somehow slightly more than I'm willing to pay for ATmega32u4. Even with radio module. So, after some digging on eBay I've found something that looked like a clone of Adafruit Feather LoRa32u4 RFM95: BSFrance LoRa32u4 II.