The unique Teddy Ruxpin was ingenious. To maintain the bear’s mouth actions in sync with the audio, it utilized cassette tapes. These tapes retailer stereo audio, which implies there are separate left and proper channels. One channel contained the audio, whereas the opposite channel managed the motor that moved Teddy Ruxpin’s mouth. I believed that was very intelligent, however that I could possibly be extra intelligent. So I constructed Useless E. Ruxpin, a Halloween animatronic ornament that has three motors all managed by a cassette tape and synced to that tape’s audio.
I got here up with this concept whereas researching our article about Erin St Blaine’s Figment dragon venture. The newer Teddy Ruxpin in that venture works in another way than the unique and easily follows digital directions whereas taking part in digital audio. However after I discovered how the unique Teddy Ruxpin labored, I used to be intrigued. I believed it will be cool to breed that performance, however with greater than only a transferring mouth. That led to this construct.
Useless E. Ruxpin has three servo motors that function independently: the mouth, the left arm, and the fitting arm. It strikes every of these in response to instructions recorded on one channel of a cassette tape and the opposite channel comprises the audio. As a result of one channel wanted to manage three motors, I could not merely translate your complete channel’s amplitude to servo place. As an alternative, I wanted a solution to encode a number of distinctive instructions on the identical channel.
The tactic I selected was to attach a particular frequency to every channel. For instance, 1000Hz is the frequency for the command that tells the mouth to open. To “learn” these instructions, I used the ArduinoFFT library working on a Seeed Studio XIAO RP2040 growth board. That runs a Quick Fourier Rework (FFT) algorithm to verify the amplitude of many various frequency ranges. If the amplitude of one of many command frequencies exceeds a set threshold, the corresponding servo motor strikes to the preset place.
I created the audio recordsdata in Adobe Audition by leaving the chosen audio on the left channel, then producing tones of the correct frequencies on the fitting channel. I then “transferred” these audio recordsdata to cassette tapes by outputting the audio from my PC’s headphone jack to a stereo receiver with a tape deck set to file. Useless E. Ruxpin performs the tapes by a transportable tape participant, with the fitting channel going to the XIAO and the left channel going to small amplifier board with a speaker.
The bodily construct was easy. I 3D-printed an inside skeleton construction, onto which the digital elements and servos mount. I then positioned a hand puppet bear “pores and skin” over that skeleton. Some paint and propsfrom a Spirit Halloween retailer helped to make it look extra sinister.
At any time when I need to give Useless E. Ruxpin new content material, all I’ve to do is combine and file a brand new cassette tape!