Author Topic: Are there any projects of the low-frequency signal generator based on the player  (Read 1103 times)

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Offline MegaVoltTopic starter

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A modern music player operates at frequencies of 384kHz and 32 bits and has a volume control and 2 output channels. This is quite enough for a good analog signal generator with low distortion and noise. It also runs on batteries for a very long time.

For example, you can record sound files with different frequencies and by selecting them to receive a signal. And adjusting the volume to get a change in the amplitude of the output.

Probably you can take the signal back and show, for example, the spectrum or something else ..

Has anyone seen oscillators based on audio ADCs? Is there anything that you can buy cheaply on aliexpress and change the firmware or some other projects?
 

Offline CountChocula

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I suspect that such a signal generator would be of limited utility, with the possible exception of audio work :)

It should be pretty easy to implement, though… you could use one of several cheap I2S decoders like this one in conjunction with some kind of MPU like an Arduino or STM32 and an audio amplifier to output waveforms up to ~45kHz on two channels based on whatever arbitrary data you can either synthesize in software or play back from memory.

The problem is that for about the same amount of cost and effort, you can probably put together a respectable signal generator for common waveforms (sine, triangle, square) between, say, 0.1Hz and 1MHz using a dedicated DDS chip like the AD9833 and a couple of cheap op amps like the LM318. With slight better parts and design, you could probably stretch it to 10-12MHz. You lose the ability to generate arbitrary waveforms, though.
Lab is where your DMM is.
 

Offline alm

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Sound cards are being used as low frequency signal generators / scopes / spectrum analyzers. Search around for software for that. Restrictions, other than frequency (the sample rate may be high, but how about the analog filtering and output stage?), are limited overload protection, only AC coupling and limited amplitude range.

They are most useful for what they were designed for: for testing audio devices. See RMAA.

I'm not sure converting a portable player and writing your own software would be worth it. Maybe if you want to use it as a very limited arbitrary waveform generator.

Offline MegaVoltTopic starter

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The problem is that for about the same amount of cost and effort, you can probably put together a respectable signal generator for common waveforms (sine, triangle, square) between, say, 0.1Hz and 1MHz using a dedicated DDS chip like the AD9833 and a couple of cheap op amps like the LM318. With slight better parts and design, you could probably stretch it to 10-12MHz. You lose the ability to generate arbitrary waveforms, though.

ad9833  Signal-to-Noise Ratio (SNR) 60 dB
Player   Signal-to-Noise Ratio (SNR) 100..120 dB

Quote
It should be pretty easy to implement, though… you could use one of several cheap I2S decoders like this one in conjunction with some kind of MPU like an Arduino or STM32 and an audio amplifier to output waveforms up to ~45kHz on two channels based on whatever arbitrary data you can either synthesize in software or play back from memory.
I understand this.... But I wanted to find a ready solution. Those. buy this box on aliexpress (this box has the best price-quality ratio) and update the firmware :)))
 

Offline MegaVoltTopic starter

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Sound cards are being used as low frequency signal generators / scopes / spectrum analyzers. Search around for software for that. Restrictions, other than frequency (the sample rate may be high, but how about the analog filtering and output stage?), are limited overload protection, only AC coupling and limited amplitude range.
I'm interested in easy portability and battery life. I understand that there are laptops. But they are big.
 

Offline alm

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Use an (old) cellphone. I'm sure there are tone generator apps.

Offline MegaVoltTopic starter

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Use an (old) cellphone. I'm sure there are tone generator apps.
A cell phone does not sound as good as a standalone player. But this is an idea. Thank you :)
 


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