Can't get sound detecting circuit to work with picaxe 28x1

Community General Discussions
,
1

Greetings from Finland

I am trying to build this sound detecting circuit from picaxes homepage to use with a picaxe 28x1. ( http://www.rev-ed.co.uk/docs/picaxe_sound.pdf )

 

 

 

 

 

 

 

 

 

 

I have breadborded the circuit and double checked every connection. The problem is that it won't react to sound in any way. I wrote this code:

main:
readadc 1, b1
debug
goto main

The reading (b1) I get from the debug window is changing when I turn the pots but it does not react to sound. I have swapped out all the transistors and the pots and tried another microphone without any difference.

I am not sure that I understand how the adjustment on this circuit works, but I have bean playing around with the pots a lot and at no point have I got this circuit to react to sound.

My setup:

 

Any help is highly appreciated!

 

***EDIT***

I breadborded the whole circuit from the beginning and the same problem. It is got to be something simple that I don't understand. This is driving me crazy! The only components I could have placed the wrong way is the microphone, diode and the transistors, but according to the datasheets they should be alright. hmm...

2

I got it working!!! :slight_smile: Now I

I got it working!!! :slight_smile: Now I can sleep again! I still don’t know what the problem was. I tested all components and they all was working. The eight time I breadboarded it it just started to work. One possible explanation could be that I have some junk in my breadboard that made a short.

Also this circuit is holding the output high for a few seconds every time there is a sound. This was not a good thing for my purpose so I changed the holding capacitor (c4) to a smaller value (104nF).

Administrators feel free to delete this post if you don’t think this post will benefit any readers.

Problem solved.