Arduino experience, someone?

[antimony]

Thanks for taking your time to reply to my post, onepowet and Chris. I am a (early) member of AU, but i havent been there for a long time.
I am not going to make a PWM controller unit at the moment, but i am trying to get myself firmiliar with radio "homebrewing".
I am making a Variable Frequency Oscillator, like these for example:
https://www.google.com/amp/s/aa7ee.wordpress.com/2018/05/11/yup-its-another-si5351-vfo/amp/

http://www.n6qw.com/Arduino_Nano_Si5351.html

I was reading Eric Dollards book on his "Crystal Radio Initiative" and the basic idea of the book reminded me of Dr Stifflers SEC's, and that got me interested in radio, and wanted to learn more, and what better way to learn then to make it yourself.

Have you guys any experience with this sort of thing?

I need to combine three (3) different "sketches" into one, or modify an existing one, but with a display like mine (OLED) instead of LCD.

[onepower]

Antimony

I was reading Eric Dollards book on his "Crystal Radio Initiative" and the basic idea of the book reminded me of Dr Stifflers SEC's, and that got me interested in radio, and wanted to learn more, and what better way to learn then to make it yourself.

Have you guys any experience with this sort of thing?

I have built many crystal radio's and I have the first version of Dr Stifflers SEC on a shelf above my bench. I had a few conversations with Dr Stiffler regarding open circuit topology and switching, he was a good man.

I also like experimenting with this kind stuff because it's cheap and easy with a steep learning curve. When I was young, before I got into all this FE stuff I noticed my crystal radio's would become supercharged when a thunder storm was approaching. Later I learned it was because the Earth/ground potential normally at 100v/m can increase by a thousand times. Here is Feynman's description of what happens during a thunderstorm...

https://www.feynmanlectures.caltech.edu/II_09.html#:~:text=The%20distribution%20of%20electrical%20charges%20in%20a%20mature%20thunderstorm%20cell.&text=The%20charge%20at%20the%20bottom,ground%20in%20a%20clear%20atmosphere.

If you can describe what you want to do and post some code we could probably help out.

Regards

[onepower]

bump in the night

[cheors]

You should use the PWM function to get a stable frequency :

For 418 Hz :

/* * Create  29/07/2016 (CHEORS)
* Processor: ATmega328P
* Compiler:  Arduino AVR

timer1 est un 16 bits
*/

void setup()
{
pinMode(9, OUTPUT);
pinMode(10, OUTPUT);

//16 bits timer
  TCCR1A = _BV(COM1A1) | _BV(COM1B0)| _BV(COM1B1) ; // Sorties complémentaires sur D9 et D10
  TCCR1B = _BV(CS10) | _BV(WGM13); //PWM, Phase and Frequency Correct, prescaler = 1

  ICR1 = 19139; // choix de la fréquence (2 < ICR1 < 65535, 16 bits)
}// Periode = 0,125 x ICR1 en microseconds (exemple F =418 Hz)
     
void loop()
{
OCR1A = ICR1 / 2; // Duty cycle D9 (1 <OCR1A < ICR1 - 1)
OCR1B = OCR1A; // Duty cycle  D10 (1 <OCR1B < ICR1 - 1)
// Here you can change the frequency with ICR1 and the duty cycle with OCR1A , OCR1B
}

[onepower]

cheors

You should use the PWM function to get a stable frequency :

PWM does not work well when generating or receiving radio frequencies other than PWM data because a radio signal is generally a sine wave not PWM. 

Note the PWM signal below, does that look anything like a sine wave?. So while a PWM signal could vary with time and invert periodically to produce a pseudo-sine wave it's just a very poor way of doing things. Antimony mentioned the better option which is to used a dedicated RF chip to manage AM/FM signal processing and modulation.

Regards