Scary Terry Audio Servo Driver Board, ST-425

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The Scary Terry board has been updated once again!

Scary Terry Audio Servo Driver Board

This circuit allows you to easily hook up audio to the circuit board to drive a servo for animating the jaw of your prop. Easily create a prop with that highly sought after animatronics effect.

Operates off of a 6 to 12VDC supply (9VDC @ 1000mA is recommended).

NOT JUST FOR DRIVING SERVO's ANYMORE!!! We have included a ULN2003 chip that allows you to drive devices such as relays, lamps, solenoids for pneumatics, etc. in sync with the sound you are playing.

The 3.5mm (1/8" stereo) style audio jack allows you to send input sound to the unit. It can driven by just about any CD player, Tape Deck, MP3 player, etc. (audio cables are not included, but are available below in our Accessory section). Use the 3.5mm (1/8" stereo) output jack to connect up your amplifier or amplified speakers.

Jumpers allow you to choose the Left or Right channel or both for the skull to follow. A passive mixer combines the two channels when you use both, instead of just shorting them together.

Two header pins are provided for easily attaching the LED Audio Eyes that come with the unit. They flash in sync with the sound you are playing. You can also set the LED Eyes to stay on all the time or have them flash with the sound!

Easily select which capacitor is used for shaping the circuits response to sound.

Power LED shows you in a glance whether the circuit has power or not.

Board size: 3" x 2.4" and 1/2" high (without connections attached).

Scary Terry's web site:

A free audio editor, called Audacity, can be downloaded from

Push Eject of the has created an excellent video of how he uses this circuit and an audio editing program to make the jaw movement on his Bucky more accurate. Click here for the video.

Manual for the ST-425

4 Reviews Hide Reviews Show Reviews

  • 5
    ST-425 Audio Servi Board

    Posted by Alex MacConnell on 13th Oct 2021

    Excellent, easy to install and use!!

  • 5
    Scary Terry Audio Servo Driver board (ST-425)

    Posted by Brian on 23rd Sep 2021

    Great addition to my talking skull! The components work flawlessly with my MP4 player, lights for eyes and jaw movement. Instructions were very detailed, specifically for dialing in the jaw MAX/MIN Regards Brian

  • 5
    Not bored with this!

    Posted by Alex MacConnell on 23rd Sep 2021

    Excellent, easy to use board with easy to follow instructions for hours of fun. Tip, use a mixer and microphone with windscreen in addition to a pitch shifter to create an ominous voice.

  • 5
    works great in my skull on my hareley davidson

    Posted by Mark R Slater on 15th Apr 2021

    would buy more if needed