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39 - Multifunction Digital VFO - Part 1: Hardware

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Nick M0NTV builds an Arduino-based, Si5351-powered multifunction digital VFO. This video (Part 1) tackles the hardware: the next video will examine the software.
HARDWARE USED
----------------------------
1) DIYmalls 1.8" TFT LCD Display Screen Module 4-Wire SPI Interface ST7735S 128x160 w/SD Card Slot for Arduino UNO Mega2560:
www.amazon.co....
2) KY-040 Rotary Encoder. Like these:
www.amazon.co....
3) Si5351 Module on Breakout Board. Like these:
www.amazon.co....
4) Arduino Nano. Like these:
www.amazon.co....
I've listed these items from one global supplier - clearly other sources are available! I hope this gives you an idea about what I've actually used myself in the construction.
DOWNLOADABLE RESOURCES
-------------------------------------------------
The Wiring Diagram is here:
drive.google.c...
The Board Layout is here:
drive.google.c...
OTHER VIDEOS THAT MIGHT BE HELPFUL
--------------------------------------------------------------------
The theory of how the VFO will work in the whole radio is here:
• 36 - Designing the Nex...
A simpler digital VFO (with full details on calibrating the Si5351) is here:
• 26 - Designing A Digit...
Thanks for watching and I hope this is helpful :)

Опубликовано:

5 сен 2024

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Комментарии : 45

@acestudioscouk-Ace-G0ACE Год назад

I found this absolutely fascinating! Not too long at all, except that the washing up still needs doing! Joking apart, as a beginner I found this easy to follow and loved seeing how the modules are linked up. I'm waiting to see the next, software video now. I will take your advice and tackle a more simple VFO first. Thanks for taking the time to make this Nick. Best 73!

@M0NTVHomebrewing Год назад

Thanks Ace! I'm pleased it wasn't too much of an ordeal! All the best with your own projects. 73 Nick

@N4HAY Год назад

Nick. The amount of work you have put into this video is really appreciated. Thanks. N4HAY

@M0NTVHomebrewing Год назад

Thanks very much Richard. 73 Nick

@antopiaaw Год назад

tips hat in Nicks direction

@M0NTVHomebrewing Год назад

Thanks very much! 73 Nick

@williamglew2851 Год назад

yes Nick a lot of interest waiting for the postman thanks and also the board layout icing on the cake

@M0NTVHomebrewing Год назад

Have fun!

@alanmacdonald65 Год назад

Fantastic bit of work there matey! I'm almost tempted to make one myself - if I can find room on the bench! Looking forward to the software video, which will be way above my level, but every day is a school day.

@M0NTVHomebrewing Год назад

Cheers Al! Fortunately you don't need to understand how every bit of the code works to use it quite successfully (otherwise I'd never be able to use it!). We'll have to make another pilgrimage to the establishment down the road before too long! Look after yourselves. 73 Nick

@tdumnxy Год назад

Congrats on putting the effort in to make this video. It was probably more work than building the project in the first place. Great job and appreciated. Before the Arduino organisation came along, this type of project would have been much harder and more daunting. (I know it could be done with PIC or other tools.) I hope people who want to build this might consider, just this once, buying a genuine Arduino board. It will cost a few pounds more but Arduino has contributed so much, from the boards themselves to the language and the IDE that ties it all together. Support the cause! And the community, the builders, makers, educators and experimenters. Thanks Nick - 73, Stephen 2E0FXZ

@M0NTVHomebrewing Год назад

Thanks very much Stephen. You're right - the Arduino was a complete game-changer and when you put that alongside the Si5351 then a whole world of possibilities were now in reach for homebrewing hams. There are several, far more powerful microcontrollers out there now and some projects will doubtless benefit from these. But for basic reliable functionality with great user support and tons of libraries etc then I think the Arduino has still got a big part to play in radio construction. Thanks again. 73, Nick

@andyash3079 Год назад

Great video Nick, really looking forward to you presenting the software and hopefully breaking down the code, not an easy task I know but please consider doing this. 73 Andy

@M0NTVHomebrewing Год назад

Hi Andy, Thanks. I'll do my best presenting the code but it's tricky doing it in a way that doesn't either bore people to death or just put them right off! Anyway, you'll have to be the judge of that when it comes out! 73, Nick

@andye2005 Год назад

Good intro Nick, For beginners in Micro controllers, it's really nice to have something with lots of LEDs, and a few switches etc already connected up. There is nothing like seeing your LED switch on and off under your own code. Pretty much all microcontrollers have development / demo boards available, which are also very very cheap. makes playing about with these things much easier. Currently I'm playing with the Raspberry Pi Pico and MMBASIC as a quick development system, works very well and brings back lots of memories of the early days of programming Soldering in the nano - not a good idea. Have a hunt for low profile IC sockets, there are even ultra low profile sockets available, and they only add about 2-3mm of height above the board. For your tuning tone, look at the PWM tone generation which I think the nano supports. Feed that through a simple LPF and you will get a very nice output. Andy

@M0NTVHomebrewing Год назад

Cheers Andy. I'll investigate low profile header sockets - sounds very useful! I have tried the PWM but it's still a square wave and so there wasn't much advantage. I will be playing with audio low pass filters though. Thanks very much. 73 Nick

@andye2005 Год назад

You don't use the PWM raw. It needs to be passed through a LPF, that converts the PWN into a sine wave etc.

@mfwwhelan7561 Год назад

Great video Nick. Very helpful for my experiments. Looking forward to the next video on the sketch. Mike, EI6AU

@M0NTVHomebrewing Год назад

Thanks very much Mike! 73, Nick

@radioguy19510 2 месяца назад

Great video. Thanks!

@M0NTVHomebrewing 2 месяца назад

Thanks very much. 73, Nick

@johnwest7993 Год назад

Excellent project Nick. I already have all of the parts to duplicate yours. I sometimes get bogged down in making software work, so it will be good to follow along with yours.

@M0NTVHomebrewing Год назад

Cheers John! All the very best with your own build. 73 Nick

@technishn Год назад

Great stuff. Ensure SI5351 is AC coupled if driving mixer direct. Additionally phase noise is improved, when the loading is high Z. Typically greater than 1 k.

@M0NTVHomebrewing Год назад

Thanks. That's interesting. I don't usually AC couple to the LO port. What is the advantage? The load is never going to be high with my double balanced diode ring mixers. It'll be 50Ω or thereabouts so I'll probably have to just live with the phase noise but I'd not heard that either. Thanks very much. 73, Nick

@technishn Год назад

@@M0NTVHomebrewing It is the SI5351 CMOS output stage driving a primary of a transformer, with one winding to ground.. It is just the switching action of the transistor that is probably preventing it from destroying itself. Re Phase noise...As just said the SI5351 has a CMOS output stage and has inherent limiting, which reduces AM noise. Driving low Z output pulls the amplitude down 3.3 to 1.6V p-p. Driving a switching mixer will reduce some of the noise, but it is probably better to drive a intermediate stage, such a logic gate, MMIC or transistor 50 ohm amplifier (with 1kohm series resistor). I have also seen an emitter follower used with lower values of emitter resistor in order to supply sufficient current

@t1d100 2 месяца назад

Because of the way the 5351 performs the math necessary to achieve different frequencies, it is not able to achieve certain radio frequencies when it is served by a 25MHz oscillator. The common 5351 modules come with a 25MHz oscillator. You need to change the oscillator to 27MHz. I have lost the link to the math proofs, but I did find it on the web. Maybe you can find it? HTH. Cheers.

@M0NTVHomebrewing 2 месяца назад

Thanks very much. 73, Nick

@jameslynes9647 Год назад

I wanted a quick audio source and had a 555, so I configured a 1KHz square wave generator. It was pretty hot, so I added four LC filter stages and had a nice sin wave at a more usable level.

@M0NTVHomebrewing Год назад

Hi James, that is similar to what I've tried. I used the Arduino for the square wave though and then sent it through 4 RC low pass filters. I ended up with a much cleaner and smaller audio signal for injection into the mic amp. In the past I've just built a dedicated 2 transistor oscillator that gave me a perfect sine wave around 1 kHz. I'm trying to optimise space this time though! 73, Nick.

@startobytes Месяц назад

done something similar but using an esp32 and a bigger 3.5 inch tft display

@M0NTVHomebrewing Месяц назад

Sounds great. I'm a big fan of the esp32 myself. It's a very versatile little MCU. I particularly love the embedded WiFi. 73, Nick

@walty28msn Месяц назад

Good evening, how are you, I'm starting an assembly, sorry for the question, the audio output, in this case you use the output from the esp32 itself, with an amplified speaker???/

@M0NTVHomebrewing Месяц назад

Hi There! I'm not sure I quite follow you. The microcontroller is an Arduino Uno and doesn't do any audio processing at all. The only audio function it has is the generation of the 1 kHz tuning tone which goes through a passive RC filter and then into a switching relay on the balanced modulator. The receive audio is completely separate - except for a tap off the audio preamp which goes into a basic envelope detector (a diode) + amp and into the Arduino for the digital S-Meter. Hope this helps. 73, Nick

@gradje74 Год назад

Great video Nick. Question: for what reason didn’t you use the I2C interface to communicate with the TFT screen?

@M0NTVHomebrewing Год назад

Thanks. My TFT screen uses an SPI serial bus - hence the connections. 73 Nick

@gradje74 Год назад

@@M0NTVHomebrewing Nick, apart from GND and VCC, on the wiring diagram you wrote the signals: CLK, SDA, RS, RST and CS However on the display in the fritzing schematic there are signals named SCK, SDA, A0, RESET and CS Also the pin lay-out seems to be different. Could you please explain which Arduino signal goes what display pin? My display is the same as in your fritzing schematic

@M0NTVHomebrewing Год назад

@@gradje74 Hi Gerard, I did mention this in the video itself. The only pin which has two completely different names is A0 which is also called RS. But just to be absolutely clear: SCK/CLK (clock) = yellow & goes to D13 SDA (data) = orange & goes to D11 RS/A0 = white & goes to D9 RST/RESET = purple & goes to D8 CS (chip select) = blue & goes to D10 Hope that helps. 73, Nick

@gradje74 Год назад

@@M0NTVHomebrewing Thank you for answering Nick. I've missed that naming remark. My wiring is OK now. The software compiled at once and after loading I measured bursts of nice pulses on the display pins. Unfortunately no light on the (Ali) display. Thanks anyway.

@M0NTVHomebrewing Год назад

That's annoying about getting no light on your display. Does it work with other sketches? I must admit I bought two of these 1.8" TFT displays from different sources: one works fine and the other is terrible - lots of lines all across the screen. If it doesn't work with other sketches then you could have a faulty screen. Hope you get to the bottom of it. 73 Nick

@multilecful Год назад

Nice work Nick, the screen looks like an ili9341 ?

@M0NTVHomebrewing Год назад

Hi there. It is not actually - it is an ST7735S. Thank you very much for reminding me of something I meant to do ... and didn't! I'll put a list in the description of what the peripherals are and where I got them. Cheers. 73 Nick