I need a 88 mhz generator

Projects General Guidance
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and I was hoping that an arduino could handle it.
The reason that I need it, is because I am trying to repair an AM/FM tuner.
I have the AM portion fixed but the FM is still not working.

I was going to use the same technique that I used for the AM portion.
I injected a 1KHZ signal into the tuner and checked each step in the path to see if it was there. Eventually the signal made it out to the speakers.
I am no good at reading a schematic but I imagine that somewhere in the FM signal path, the tuner will filter out or discard signals that do not fall within the FM frequency band. 88mhz ~ 108mhz.

thanks

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Get yourself a cheap Analog Devices DDS chip like an AD9850 on eBay

(sp. "MHz")

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[quote author=Perehama date=1535649680 link=msg=3858044https://www.arduino.cc/en/Tutorial/DueSimpleWaveformGenerator[/quote]

void loop() {
  // Read the the potentiometer and map the value  between the maximum and the minimum sample available
  // 1 Hz is the minimum freq for the complete wave
  // 170 Hz is the maximum freq for the complete wave. Measured considering the loop and the analogRead() time

That is going to fall a little short of the desired 88 MHz. :slight_smile:

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johnwasser:
That is going to fall a little short of the desired 88 MHz. :slight_smile:

Now that you have my head thinking straight, Arduino isn't a good fit for that high of a frequency. It's crystal is traditionally 16 MHz, but can be clocked up to 20 MHz. Any signal generation would be based on that clock speed, or a slower clock, but not higher.

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I was hoping that an arduino could handle it.

Wishful thinking, and I doubt it.

I was going to use the same technique that I used for the AM portion.
I injected a 1KHZ signal into the tuner and checked each step in the path to see if it was there. Eventually the signal made it out to the speakers.

If you were really injecting a '1KHZ signal' then presumably its a square wave, then that could produce enough harmonics to make its way through a AM receiver to the speakers.

I am no good at reading a schematic but I imagine that somewhere in the FM signal path, the tuner will filter out or discard signals that do not fall within the FM frequency band. 88mhz ~ 108mhz.

This is not the place to be discussing fixing radio tuners

There is a good reason why a low frequency square wave generator will get through a typical (low frequency) AM receiver to the speakers, but that will be of no use whatsoever for tracking problems in a (high frequency) FM receiver.