Robot design

[maxbrenner]

Hi All,

I'm trying to design a robot mouse thats "nose" would twitch when it hears a certain volume. for instance when V= 15V, it's nose twitches and when v=0V, it's nose stops twitching.
How would you build this circuit using analog circuitry?
Also, how do you sense average volume and check against a threshold?

Thank you!

 

[MikeMl]

If the twitching starts at 15V, your turn-on threshold is 15V .

If the twitching stops at 0V, your turn-off threshold is 0V.

Sounds like you need a Schmitt Trigger circuit.

 

[#12]

You sense volume with a microphone. To find average volume over a certain amount of time, you use an integrator circuit. To check against a threshold, you use a comparator. All of these things require decisions about frequency or time, and those depend on the environment. For instance, is your mouse goung to be sneaking around the christmas tree or fighting for his life in a public contest? How long do you want the surrounding how loud before the nose will start responding? Lots to consider.

 

[maxbrenner]

Thank you!

I'm new at this so pardon me if I make mistakes. So I have a micrphone that outputs a voltage signal in audio frequencies that can get large as +/- 0.1 V. these amplitudes have to be converetd in to a DC voltage level between 0 and 2 V that reflect the amplitude of the wiggles averaged over 1 s.
So I guess I need a gain stage, a band pass filter,a peak detector and a schmitt trigger for my circuit??

 

[#12]

Basically correct, except I wouldn't use a schmidt trigger because you can make a schmidt trigger out of an op-amp, but you can't make an audio amplifier (gain stage) out of a schmidt trigger. The bandpass filter can be done by sizing capacitors on the gain stage, so it doesn't need to be a seperate building block. The peak detector goes to the "fake" schmidt trigger, and viola...3 op-amps in a single package will get you where you want to go. (Get a quad op-amp, there's always a use for the spare.)