I'm fairly new to this so I'm not too good a reading the schematics like the ones Daniel provided in another post:
Here also is a nice diagram showing how to wire the two-pin variety of electret mics into your amplifier. Power is supplied through a resistor, and the signal is extracted from that by the capacitor.
D
My question is how do I wire a two pin electrets mic to an amplifier (I'm using an LM324). Where do I need resistors and capacitors and how powerful do they need to be?
I have failed to find any explanations (which gave sense to me) on the logic behind this on both Google and in O'Sullivan and Igoe's book on Physical Computing. So I had to give in and ask for help...
On the mic package there is one contact that is connected to the case of the mic. Connect that to ground. Connect the other pin to an analog input through a capacitor, as shown in that diagram. Finally, connect the mic pin (the one that is not ground) to +5 through a 5.6K resistor.
@akav: if youa re talking about a small "can" type electet mic (the type that is 5 or 20 mm across), then you have to use the internal amplifier, it won't work without it.
connecting these mics is easy, there are just three connections:
mic ground( the outside part of the blue shielded cable) >> Arduino Gnd
Arduino +5 >> 3.3K resistor>> mic positive pin ( mic yellow wire)
mic output (small wire inside of shielded cable) >> .1Uf capacitor>> Amplifier input
There is a schematic showing the same thing here, except their positive wire is marked red instead of yellow.
The only problem with these mics is that you usually get them without data, so you don't know what the best values are to use for Vcc and the limiting resistor... so it is a bit of trial and error. If you know someone with an oscilloscope, you can breadboard it and then adjust the Vcc and Vcc resistor value to get the best output... or you could ask the place you bought it for the manufacturer part number, and that would lead you to the datasheet, with all the pertinent info.
Thanks Daniel for trying out here I must admit though I'm still a bit baffled.
First
In the amplifier there are two inputs: one minus and one plus. From where do I get the two inputs?
Second
The pic is wrong sorry! I only have two outputs from the mic - the "blue" cable isn't shielded (I actually tried to buy some similar to the pic but they just gave me more with two outputs)
the two wire ones have the power supply wire integrated with the audio wire. Easy to connect, but if you want the quick solution, the one that lets you focus on the art or design rather than the signal to noise ratio , try one of these readymade amplifier boards:
If you want to do it yourself, the two-pin variety of electret mic gets hooked up as described above, although I had left out the amplifier in the earlier post. The mic only puts out a small signal, so you do need an LM324 or similar aplifier circuit.
Anyway, on a 2-pin mic package there is one contact that is connected to the case of the mic. Connect that to ground. Connect the other pin to an analog input through a capacitor, as shown in that diagram. Finally, connect the mic pin (the one that is not ground) to +5 through a 5.6K resistor.
There is a diagram on this page
What do you want to do, detect sound levels? There is a schematic here for that.
D
You are right I want to focus on the design and it gets frustrating when you realize you might be in over your head.. I need to detect sound level to set of a motor so especially thanks for the last link.
