« Back to Store
The front of a red Texas Instruments Speak and Spell, standing upright: the molded carry handle across the top, the black display window below it, and the yellow keypad with orange letter keys and the Speak and Spell logo. Completely unmodified.

Drone synth in a Speak & Spell · Made to order

Speak n Synth

Synth Made to order

A drone synth living inside a Speak & Spell, sharing its speaker. Nothing was bent to get it there: the toy's own board is untouched and it still spells, so you get two instruments in one case and neither one ruins the other.

  • TypeDrone synth added to a Speak & Spell. Not circuit bent
  • CircuitSynthrotek 4093 Chaos NAND - a CD4093 quad NAND gate
  • HostTexas Instruments Speak & Spell, still fully working
  • AmpLM386 with its own volume pot - the board will not drive a speaker without it
  • OutputThe toy's own speaker through a mini mixer, plus a line out carrying both
  • ControlsSix knobs and three toggles through the back, including a power starve on the synth
  • PowerTwo supplies: the toy on its own AAs, the synth on a 12V rechargeable pack with a charge port
  • AvailabilityMade to order on a donor toy
$225 free shipping Buy with Card Email First

Made to order. Buying starts the build rather than shipping a finished one - I source a donor Speak & Spell, fit the synth, and test it before it goes out. Email me first if you need it by a particular date, or if you want a particular era or condition of donor.

What it does

The synth is a Synthrotek 4093 Chaos NAND, built around a CD4093 quad NAND gate. Synthrotek describe what comes out of it as low pulsing drones, random robotic chaos and high-pitched laser sounds, which is where the two words on the tape come from.

The board will not drive a speaker on its own, so there is an LM386 amplifier with its own volume pot, and a mini mixer after it so the drone and the toy come out of the same speaker. Six knobs and three toggles come through the back.

What each knob does is not a question with a tidy answer, and I am not going to pretend otherwise. It is called Chaos for a reason.

Two of them are not a mystery, though. One is marked VOL on the case, and one is a power starve on the synth: wind it in and the drone's supply sags, which is where the sound starts coming apart. The rest belong to the Chaos NAND and they are the ones I cannot give you a straight answer about.

What is actually inside it

Five things share the case, and none of them replaced anything:

  • The original Speak & Spell. Untouched board, still spells, still does everything it did in the shop. It runs on its own AA batteries, the way it always did.
  • The Synthrotek 4093 Chaos NAND, a CD4093 quad NAND gate wired as the drone synth. This is the part that makes the noise.
  • An LM386 amplifier board. Not optional: the NAND board will not drive a speaker on its own, so without this the synth is silent no matter what the knobs do.
  • A power starve on the synth, on its own knob.
  • A 12V rechargeable battery for the synth side, with a charge port in the side of the case. So the two halves have separate supplies: charging the synth does not touch the toy, and flat AAs do not stop the drone.

Both halves reach the toy's own speaker through the mini mixer, and there is an OUT jack that carries the same blend, so a cable gets you the Speak & Spell and the synth together rather than one or the other.

Made to order, and what that means

The one in the photos is not for sale. It was the first one and it belongs to someone who was fairly clear about keeping it. Yours would be a new build on a donor Speak & Spell, with the same circuit, the same amplifier and mixer, and the same layout through the back.

Donor toys are secondhand and they vary, so no two of these will look identical. Shell color, keypad wear and the exact shade of red all depend on what I can find. If you want a particular era or condition, say so and I will look for it.

The full build is written up on the project page: Speak n Synth.

Demo

Demo filmed by Onion Madder on the first one.