Hi guys
Am hoping someone with more experience than me might be able to help point out where I might be going wrong with the little project I'm currently trying to do. I've attached an image showing the filter circuit design that I got from an online calculator, based on the bandwidth I want this to allow through (approx 900-2000hz), and have made up the circuit, and coupled it to a KY-037 microphone module, with the analogue output from that being the input to the filter circuit, the gnd joining the filter gnd, with 5v supplied to it from an arduino's 5v output.
The filter circuit is powered by a 9v battery direct to the LM348 op-amp, and the output from the circuit goes directly to a small speaker.
I hope that makes sense when you see the filter diagram! One important thing to note with the filter diagram is the figures all have been changed after that screenshot - I changed the influencing factor of the capacitor value from 0,01uf to 1uf (as I have loads of those), which caused the resistors to be 100th of the value shown on the image, so the 17k resistor is now 170ohms etc (sorry for confusing things!):
Basically apart from a slight crackle from the speaker when I power up the circuit I get no output from the speaker. When I test with a meter the output from the mic module (while in situ) it gives me just 12mv and does not vary when subjected to noise.
However! When I detach the mic module's analogue output from the filter circuit, and then test the output of the mic module I can see that it is now around 122mv baseline, but increasing according to noises, as I would expect.
I'm fairly new to building circuits like this from scratch, although when I was a youth about 25 years ago I used to etch a few basic circuits that I tried to make with components harvested from broken electronics at least!
This is the mic module I'm using:
If anyone has suggestions on what I might be doing wrong here I'd be really grateful, thankyou.
Cheers!
Am hoping someone with more experience than me might be able to help point out where I might be going wrong with the little project I'm currently trying to do. I've attached an image showing the filter circuit design that I got from an online calculator, based on the bandwidth I want this to allow through (approx 900-2000hz), and have made up the circuit, and coupled it to a KY-037 microphone module, with the analogue output from that being the input to the filter circuit, the gnd joining the filter gnd, with 5v supplied to it from an arduino's 5v output.
The filter circuit is powered by a 9v battery direct to the LM348 op-amp, and the output from the circuit goes directly to a small speaker.
I hope that makes sense when you see the filter diagram! One important thing to note with the filter diagram is the figures all have been changed after that screenshot - I changed the influencing factor of the capacitor value from 0,01uf to 1uf (as I have loads of those), which caused the resistors to be 100th of the value shown on the image, so the 17k resistor is now 170ohms etc (sorry for confusing things!):
Basically apart from a slight crackle from the speaker when I power up the circuit I get no output from the speaker. When I test with a meter the output from the mic module (while in situ) it gives me just 12mv and does not vary when subjected to noise.
However! When I detach the mic module's analogue output from the filter circuit, and then test the output of the mic module I can see that it is now around 122mv baseline, but increasing according to noises, as I would expect.
I'm fairly new to building circuits like this from scratch, although when I was a youth about 25 years ago I used to etch a few basic circuits that I tried to make with components harvested from broken electronics at least!
This is the mic module I'm using:
If anyone has suggestions on what I might be doing wrong here I'd be really grateful, thankyou.
Cheers!