EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: generatorny on April 17, 2015, 01:21:28 pm
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Hi guys,
I need some advice, I got cheap FG-100 DDS of Ebay and did not notice that it range is from 1 Hz to 20 kHz. For my application I need only range between 0.1 Hz and 1 Hz. Is it possible to make some changes internally or I just wasted my money. Any help is appreciated.
Cheers
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Hi guys,
I need some advice, I got cheap FG-100 DDS of Ebay and did not notice that it range is from 1 Hz to 20 kHz. For my application I need only range between 0.1 Hz and 1 Hz. Is it possible to make some changes internally or I just wasted my money. Any help is appreciated.
Cheers
If you just wanted a square wave, you could wire up an external divide by ten counter and feed the counter with the FG-100.
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This one looks like a µC (likely AVR) doing DDS in Software. Without a circuit plan it is a little difficult so say how to modify it. In Principle there are 2 methods to lower the frequency:
1) change the Hardware - e.g. change the crystal to a slower one.
2) change the software - there are man similar projects out there, and some even provide software including source code, so one could adapt it to a slightly different hardware (e.g. different pins used). However a first step for this would be finding the circuit. If the µC is in a socket you can start over with a new and keep the original as Backup. You also need a programmer Hardware - unless you have this, this wold be the hard way.
It is possible that the amplifier uses AC coupling, though 1 Hz is allready quite low. If so a larger capacitor may be helpful.
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:)
Yes lowering the frequency of oscillator did the trick. I went from 30Mhz to 5.0688Mhz and did not affect quality of sine wave much, and my output is proportional to oscillator change so it went from 1Hz down to 0.17Hz which is what I need.
Guys thanks for the input.
Cheers