PICAXE Sound Detector Circuit
The circuit above is how to hook up a microphone to a picaxe to either have it detect the presence of sound (using a digital pin) or the sound level (readadc). The question I have is in a couple spots it connects a capacitor to the middle of a resistor. Does this mean you connect it to both sides of the resistor?
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@ Sun, 2010-07-25 01:42
I have been trying and
I have been trying and trying but just can't get this circuit to work... I have breadboarded it alot of times and swapped out every single component. I know it is probably something easy that I just can't figure out or have understanded wrong. This damn circuit is bothering me like acid in my eyes.
@ Tue, 2010-03-09 22:02
C2 huh?
@ Wed, 2010-03-10 00:28
It's a pretty tiny cap, so
It's a pretty tiny cap, so probably just there to allow high frequency noise bypass the 100kΩ resistor. As you've already discovered, not critical at all =)
@ Sat, 2009-11-14 23:37
The resistor with an arrow
The resistor with an arrow in the middle should be a potentiometer, for tuning purposes.
If you know the value needed they could be swapped out for two resistors in a voltage divider setup.
@ Sat, 2009-11-14 23:40
After I posted it I figured
@ Sun, 2009-11-15 00:00
That's not how I read it
The sweeper of the pot is always in the middle of the schematic drawing of the resistor. I sweeps between Max and min. This drawing has the word Max in an unfortunate spot.
Min and Max are always the two "fixed" terminals on the pot. The sweeper is the variable one.
@ Sun, 2009-11-15 00:03
So max is the right, min is
@ Sun, 2009-11-15 00:31
Left/Right or V+/Gnd
Not sure about Left vs Right. As long as "Min" is connected to V+ (4.5 V in this circuit). "Max" connected to Q1's Collector. The pot does not really have a "correct side up". It's not polarized. So any side connected to V+ will do. After connecting it that way, you will consider it "Min".
Whatever that means for you. I don't get the working or application of this circuit well enough.
@ Sun, 2009-11-15 00:33
http://www.rev-ed.co.uk/docs/
http://www.rev-ed.co.uk/docs/picaxe_sound.pdf
Any idea of what the SET ZERO means on the other pot?
@ Sun, 2009-11-15 00:58
I think it's to adjust the
I think it's to adjust the output voltage. If sensitivity adjusts how well the mic can hear, Zero adjusts what voltage is output at what sound level.
Set sensitivity to MIN (i.e. the mic hears nothing) and adjust Set Zero so the output is 0 volts. Then bump sensitivity up until it can hear what you want it to hear (speech for example, but not the radio in the other room). If it then hears normal speech but doesn't output a high enough signal to trigger your micro's input you can tweak Zero up a bit to raise output voltage until the micro responds.
edit = What Rik said ;)