Hey guys
I am working on a project to create a device which the program detects frequency.
the frequency detection was working fine until it is connected to Arduino, then the noise disrupted the signal.
Is there a way to silence the noise from arduino?
EMI problems have no general solution. You have to provide more details, diagrams, photos, etc.
here is the photo of the schematics.
it is a electret amplifier(pic1) connected to frequency detector (pic2 above)
I see no frequency detector. You say pic1 and pic2, but you only posted one fuzzy image.
I see no photos.
just done it
I still see no frequency detector. The first schematic is just a mic preamp. The second splits the signal into a peak detector and a comparator that squares the signal and converts it (crudely) to digital voltage levels.
You said that the "frequency detection was working fine", but there is no frequency detector anywhere in the circuits you have posted. What method did you use to test the circuit? How do you know that it doesn't work with the Arduino?
Also, your schematics mention a filter that I can't find. The first says, "OUT - to filter in", the second says, "IN - from filter".
What does your prototype look like? Have you followed proper layout and grounding procedures? Please show a photo of that.
I am working on a project to create a device which the program detects frequency.
What do you hope to detect the frequency of?
A microphone suggests it is a voice or instrument. It is very difficult to detect the frequency of a natural sound like this due to all the harmonics in the waveform. We get this one a lot and unless you are looking at detecting something with a simple waveform it will not work very well.
You can get the note, with a lot of computation that is A to G, but you will find it impossible to get the octave of the note.
So what are you wanting to measure and what do you want to do with the measure once you have it?
wjsdbf123:
here is the photo of the schematics.it is a electret amplifier(pic1) connected to frequency detector (pic2 above)
I would buffer the low-level signal before the comparator, otherwise there is a definite risk
of switching noise getting back to the microphone from the comparator or its supply.
Make sure the buffer opamp has decent decoupled analog supply, not raw Arduino 5V,
for best isolation.
You may also want to experiment with variable amounts of hysteresis on the comparator
with positive feedback, another reason to need a buffer before it.
MarkT:
I would buffer the low-level signal before the comparator
Well, that might be part of the yet to be posted "filter" circuit that is between the preamp and the comparator. I already pointed out that the schematics are incomplete, they don't show the actual supply connections so it is guesswork as to what voltage the opamps are using. This is a good example of how incomplete information can make it nearly impossible to help someone.
Also, the really basic questions I asked about what testing had been done to reach the conclusions that were reached, remain unanswered. It is really frustrating to deal with someone like this.
