Finished Pieces

Grillo Drumbot

    casperelectronics Speak and Spell: Grillo Drumbot

    Click the above pic for an enlarged diagram.

    This is an Italian Speak&Spell with the standard array of modifications as well as an added timer module. The timer has several settings and applications. It can be used as an adjustable pitch modulation, as a rhythmic “hold” effect or as a rhythmic pushbutton trigger (any of the pushbuttons on the main touch plate can be triggered by the timer by dialing that button into the two selection knobs).

    casperelectronics Speak and Spell: Grillo Drumbot

    The drumbeat-like sounds are created using the “hold” effect. When this effect is on, the timer activates the “hold” effect every time the light blinks (once every cycle…at a 50% duty cycle).

    casperelectronics Speak and Spell: Grillo Drumbot


    • 1/4″ audio output jack with internal speaker switch
    • Volume adjustment
    • Power adjustment
    • Power reset button
    • “On” hold switch
    • Pitch adjustment
    • Stable glitch
    • Slow-mo glitch
    • Short glitch
    • Short loop/hold with adjustment and momentary off pushbutton
    • Long loop with adjustment
    • Long loop randomize with adjustment
    • Tone generator pushbutton

    Added Circuitry:

    • Timer circuit with relay and wave shaping components.
    • Power regulation board for providing adequate and stable power to the Speak&Spell and the timer board.

    Timer features:

    All of the following features are linked to the same timing circuit and can be used together or independently.

    • Rate adjustment
    • On/off switch
    • Pulse indication light
    • Pitch modulation on/off switch
    • PM depth adjustment
    • PM slope adjustment (fades from triangle wave PM to square wave PM)
    • Auto trigger on/off switch
    • Two knobs (a letter knob and a number knob) for selecting a button from the S&S touch pad to be triggered.
    • The “letter” knob has a setting labeled “loop.” This setting allows the timer to activate the “short loop” effect. Whenever the pulse indication light is lit, the short loop will be activated.

    casperelectronics Speak and Spell: Grillo Drumbot


    One Response to “Grillo Drumbot”

    • 1

      WSM said:
      October 5th, 2010 at 2:21pm #

      Hi casper,

      I love your work, all of your documentation is very helpful to amateur benders like me.

      I am bending my first S&S, and I think I may have killed the keypad by drilling through the battery compartment. The two rotational switches seem to be a great way to get around using the keypad, and I think I should be able to figure out how that works with a little experimentation.

      Question: how do you set up the LFO to trigger each letter? do you use a NPN gate of some sort or just by connecting the output of the LFO to the keypad?


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