Category Archives: Arduino

My second homebrew Arduino/si5351 Digital VFO-Controller

Back in February 2017 I scratch-built my first Arduino and si5351 VFO. Here’s my second one.  It is a generic Nano/si5351 module wired up to Farhan’s Raduino circuit. The si5351 is on an Adafruit breakout which includes a 3.3v regulator and crystal.  Everything else is as per Raduino other than the presence of a second 7805 regulator for the LCD (and a 1000uF electrolytic storage capacitor) which will allow testing of Pavel CO7WT’s scheme for saving the VFO frequency to the Arduino’s EEPROM when the power drops.

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DIYODE Issue 1 July 2017

DIYode, a new Australian DIY electronics magazine has just launched. I picked up my first edition from the Jaycar counter. It’s thick, glossy and oozes high production values. There’s an nostalgia in having a current electronics magazine on the coffee table. It takes me back to the 1980s when Electronics Australia, Silicon Chip and Electronics Today International bought circuits, components, kits and articles, not to mention ads and specials from hobbyist-focused advertisers like Dick Smith into our lives every few weeks.  Those days are gone forever.  Smartphones and the internet have put every circuit diagram and datasheet at our fingertips, and have spawned global communities which put world experts just minutes or hours away.  So in July 2017, where does a glossy DIY electronics magazine fit in this smorgasbord of information and community?

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Homebrew 40m SSB rig gets CW, keyer, break-in, AGC and metering

A couple of ‘solder sessions’ finished all the wiring, debugging and testing required to deploy my Arduino Nano keyer and SWR/power meter, and the LED LDR AGC and S-meter modules into my homebrew 40 meter SSB rig (MST Mk1 from OzQrp).  Before reassembly I sprayed the front and rear panels, and added my preferred DecaDry white lettering and a protective coat of  clear satin sealer. It’s now resplendent with all the expected features of a SSB/CW monoband portable rig.

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Saving an Arduino-controlled Digital VFO frequency over a power cycle

Following the success of My First DDS VFO, complete with Arduino script programming, I found myself interested in mimicking more of the features of the digital dials in ‘real’ rigs. Like dynamic incremental speed-tuning, where the tuning rate increases or decreases dynamically depending on how fast you spin the dial. More on this later. A more achievable feature is to have the band, mode and VFO come up on the frequency where you left it at the last power-down. This involves writing these parameters into the Arduino’s EEPROM, using the EEPROM library.

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Yet another Arduino Nano and si5351 Digital VFO/BFO

The second weekend in January 2017 afforded time to build something I’ve been wanting to build for several years, my first DDS VFO. I’ve built a kit DDS VFO with pre-soldered surface mount parts and burned-in firmware, but this was to be a scratch build with Arduino Nano, Arduino/C code with modifications, and a Silicon Labs si5351 on a breakout board. I used the wiring map and script from Tom AK2B. It is modified from one by SQ9NJE and uses Jason NT7S si5351 library. The script is elegantly simple, supporting a single push-button to cycle frequency increments, and dealing with encoder interrupts, contact debouncing, refreshing the LCD display, IF offset and VFO/BFO outputs. At the code level Jason’s si5351 library hides the gutsy device interfacing, giving you just a handful of common-sense functions to call… for example, set_frequency() takes as its argument the frequency in centi-hertz (1/100th of a hertz) and the ‘clock 0/1/2’ flag. It couldn’t be simpler. The Adafruit board contains the si5351 and a 25MHz clock (from local IoT supplier Core Electronics).  I chose Veroboard as the substrate for the controller proper, and it proved suitable. Here’s a video demonstration of the VFO’s features.

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