Last week I worked on getting familiar with the Emic2 text to speech module connected to and Arduino. This week I’m working on a way to get the mouth of my robot to move in sync with the words that Emic2 is saying. I realize that I could take advantage of the Arduino and write some code that would do just that, but I’d rather find a solution that takes advantage of the audio signal that Emic2 is generating. Since there is a rise and fall in sound signal amplitude, this could translate to a fluctuating voltage connected to a motor. By turning at variable speeds in proportion to the variable voltage of the audio signal, the motor could move a cam that opens and closes the mouth in sync with the words… sort of.
That’s what this circuit does in a sense. The signal enters the circuit through the two small transistors that serve as a switch and an amplifier. When a sound signal is present, the first transistor turns on and allows the second transistor to amplify the sound. This signal then goes to the gate of the MOSFET which in turn switches on and allows current flow across the drain and the source. This current flow can power a motor or servo to open and close the mouth on a robot. As you’ll see in the video, I managed to get a gear motor turning by inputting the sounds from the Emic2.
Next week I’ll tackle the code to generate random phrases. Still working on that one. Arrays? Switch/case? Time to learn more C.
Till next time….
keep on hackin.
Hey Dino. I have used this circuit to animate a plastic skull with a hobby servo. It works really well, fast to make, and cheap, too!
That’s a great board! Thanks for sharing the link. 🙂