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Can any one help me, I need to make a sine-wave of 455Khz for use in aligning a Super 7 - AM Radio.

I looked into buying a function generator but I have an Arduino UNO. Can this do the tasks?

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  • No, but realize you don't need a sine wave - a square wave will work too, as it's unlikely that the IF can be mis-tuned to the third harmonic (though you might be confused by that coming in through the front end). Also, you might be able to use an integer fraction of 455 KHz. If you wanted to be really, really, clever you could probably use an Arduino to make a sort of PLL synthesizer by dividing the internal oscillator to 455 KHz and having software adjust its calibration so a further division matches some other slow speed reference source. But there are inexpensive chips you can buy... Jun 13, 2018 at 14:28

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The Arduino does not has a DAC (digital analog converter), so you cannot make an output varying in voltage (except for 0V / 5V) by default.

The PWM outputs use 0V/5V with duty cycle but this is not a sine wave.

So you need additional hardware anyway.

Also, regarding speed if you have a DAC. Assume 16 MHz for the Arduino, having a 455 Khz sinewave, you have about 35 clock cycli per complete sine wave. The sine values you can store in a table, but you need probably at least 3 or 4 clock cycli per sine wave value (to fetch the value from the table and to send it to the DAC), this results in about 8 values which will give a very rough sine wave.

So I would go for a separate sine wave generator.

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    For example, AD9850
    – MichaelT
    Jun 13, 2018 at 9:24
  • Or ICL8038 if you want to go cheaper Jun 13, 2018 at 9:30
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If you don't want to buy a chip, and you do have a few other parts laying around, it would not be hard to do a simple oscillator with Op Amps and get a nearly true sine wave. Alternatively an inverter (74ls04, or any inverting gate chip cmos or ttl) with an R-C can be made into a square wave generator, and another RC or two could get it to approximate a sine wave.

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