Electret Mic to Drive Logic (Clap or Whistle)

[Ike]

What is the easiest way to drive a logic high input pin on a
microcontroller with an electret microphone?

I want the microcontroller to be able to detect a clap or whistle or
any spike in sound pressure. Sound quality and frequency are not
important.

The catch is that the circuit MUST run from a single 3v lithium CR2
battery.

The microcontroller is a 12F675 and it has an ADC, so I could use the
ADC if it is not practical to get 2.5v to 5v for a digital input pin.
But I think I still need to boost the electret's output for the pin to
be able to detect a change.

 

[John Fields]

What is the easiest way to drive a logic high input pin on a
microcontroller with an electret microphone?

I want the microcontroller to be able to detect a clap or whistle or
any spike in sound pressure. Sound quality and frequency are not
important.

The catch is that the circuit MUST run from a single 3v lithium CR2
battery.

The microcontroller is a 12F675 and it has an ADC, so I could use the
ADC if it is not practical to get 2.5v to 5v for a digital input pin.
But I think I still need to boost the electret's output for the pin to
be able to detect a change.

---
View in Courier:


+3V>-----+-----------+------+-------+
| | | |
[3k3] [1M] | |
+----+ | | | |
| |--+--[0.1µF]--+------|------|+\
|MIC | | | | >--->Vout
| |--+ | [1M]<---|-/TLV
+----+ | [1M] | | 3701
| | | |
GND>-----+-----------+------+-------+----->GND

The 3.3k resistor might have to be changed depending on the mic you
use.

With no sound into the mic, adjust the 1 meg pot until Vout goes
high, (about 1/2 scale) then back off until Vout goes low. Then,
with sound into the mic, adjust the pot for the sensitivity you
want.

 

[Ike]

Hi John...

Wow, I really appreciate your post with this circuit! This will work
perfectly!

I can't seem to find a TLV3701. TI lists it as obsolete, and I can't
find a source at the standard outlets (Mouser, Newark, Jameco, etc.) or
on Google. DigiKey lists them, but they don't have the PDIP as a stock
item (I can't use SMD at this time).

Is there another device that can be subbed?

Thank you!

 

[John Fields]

Hi John...

Wow, I really appreciate your post with this circuit! This will work
perfectly!

I can't seem to find a TLV3701. TI lists it as obsolete, and I can't
find a source at the standard outlets (Mouser, Newark, Jameco, etc.) or
on Google. DigiKey lists them, but they don't have the PDIP as a stock
item (I can't use SMD at this time).

Is there another device that can be subbed?

 

[Ike]

Hi John...

Excellent! Actually, when I searched for your reference to "TLV3702IP"
I found the "TLV3701IP" which is not obsolete! I'm not sure how I
missed that one. I have ordered samples from TI.

Is there a way to achieve this functionality with transistors?

Thank you!

 

[John Fields]

Hi John...

Excellent! Actually, when I searched for your reference to "TLV3702IP"
I found the "TLV3701IP" which is not obsolete! I'm not sure how I
missed that one. I have ordered samples from TI.

Is there a way to achieve this functionality with transistors?

 

[Ike]

Hi John...

I just found this circuit...do you think this circuit will work?

http://www.csmrobotics.com/mic_amp_02.gif

Thanks!