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Nothing In Here

Three months bending a VTech Little Smart Super Sound Works, and the one thing in it worth having

This is a guide about not finding anything. I spent roughly three months poking at the board inside a 1996 VTech Little Smart Super Sound Works, and there are essentially no bends in it. I am writing that down because nobody else has, and because a negative result you can trust is worth more than another tutorial for a toy that was easy.

⚠ Before you start tap to expand / collapse

Probe on batteries, not a bench supply. Four AA cells cannot deliver much, so a slipped probe that shorts the rail is a dead battery rather than a dead board. A supply with real current behind it turns the same slip into smoke.

Some bends scramble the board, and that is not damage. One of the two described below leaves it confused enough that it stops responding properly. Pull the batteries, wait, and put them back; it comes up fine. Know that before it happens so you do not assume you have killed it.

Desoldering the crystal is the one step you cannot walk back. Everything else here is a probe touching a pad. Lifting the clock off the board is a commitment, so be sure you want the modification before the iron goes near it.

It is a children's toy, so the case is thin and the screws are soft. Take your time with a properly fitting driver, or you will round the heads and have a much worse afternoon than the circuit was ever going to give you.

Why this toy at all

The Super Sound Works is a 1996 children's keyboard: twenty-five keys, two speakers, four drum pads, a grid of about fifty instrument and animal voices, rhythms, a record and playback, and a Sound Creator section. It runs on four AA cells. They turn up secondhand cheaply and they get listed as "great for circuit bending", which is how I ended up with one.

The wider VTech Little Smart line genuinely is good bending material. There are writeups and videos out there for the Talk 'N Lights, the Talking Toy Shop, the Alphabet Desk, the Spelling Book. Every one of those is a different model. For this one there is nothing, and after three months I think I know why.

What I probed

All of it. Every capacitor, every resistor, the chips themselves. The usual method: a jumper with a probe on each end, power on, and work systematically across the board touching pairs of points and listening.

The result was the same nearly everywhere. Bridging two points fires off a sound the board already makes. Not a broken version of it, not a stretched or detuned one, just one of its own samples played at a moment you did not ask for. That is not a bend. That is a button you soldered on badly.

The two that did turn up, and why they are not in mine

  • Lights in time with the beat. One connection made the toy's lights flash along with the rhythm. It works, it is stable, and it is kind of lame. It does nothing to the sound at all, which is what I was there for.
  • Random crashes into songs. This one sounds more fun than it was. The toy would lurch into one of its demo songs unpredictably, which was unpleasant rather than interesting, and worse, it scrambled the board badly enough that the only way out was a full reset. A bend that needs a power cycle to recover from is not a performance control.

Neither was worth keeping, so neither one is in the instrument I built out of this toy.

The one thing worth having: the clock

What the board does have is a crystal, and it turns out that is the whole instrument.

A toy like this generates everything from that single clock. The pitch of every voice, the speed of every rhythm, the rate its recorded sounds play back, all of it is derived from the one part. So changing the crystal does not retune the keyboard. It makes the whole toy run fast or slow, with everything moving together, which is a far stranger and bigger change than a pitch control on a single oscillator would be.

There are two ways to do it. An LTC1799 is a programmable oscillator that replaces the crystal and gives you a knob, so the clock becomes continuously variable. Or you can fit several crystals on switches and pick between them.

I went with crystals, at first because I could not find my LTC1799s and I have hundreds of crystals in a drawer, and afterwards because I think it is the better answer for this toy. A sweep sounds great once and then you can never find that spot again. Switches give you settings you can come back to: mine has four, they are stable and repeatable, and one of the four is the crystal the toy came with, so the stock instrument is still a position on a switch rather than something I threw away.

Three switches, four crystals. One toggle chooses a bank, high or low, and then one toggle per bank chooses between the two crystals in it. Two fast, two slow, stock among them.

What to add instead

If the board will not give you bends, the honest move is to stop asking it for them and add something that will.

  • A line out. The noises this thing makes are genuinely good and they deserve a way out of the box. A switched jack means the speakers cut when you plug in.
  • An echo. I fitted a CD2399 module with depth, feedback and mix brought out to the panel. The way to modify one of those boards is Darren C. Shaw's PT2399 tutorial, which I mirror here with his permission. His guide is written for a PT2399 board and mine is marked CD2399, which is the same part under another name, so the modification lands the same.

Neither of those is a bend, strictly. The crystal swap is: that is the host's own circuit rewired. The rest is building the toy a sound it never had.

So should you buy one to bend?

Honestly, no. Not unless one of these is true:

  • you have an LTC1799 already, or
  • you have a bunch of crystals already, or
  • you just really like random barnyard sounds and silly songs.

That third one is not a joke. It is a charming toy and it makes wonderful noises on its own. There are plenty of demos of the stock unit on YouTube, so listen to one before you buy a donor. If you like what you hear, know that the clock is the only handle on it, and buy it for that rather than in hope of finding something else in there.

I would rather you spend your three months on a different toy than repeat mine.

Where mine ended up

In a keyboard I called the Super Sound Warps: four crystals on three switches, the CD2399 echo, a switched line out, and every stock voice, drum pad and rhythm still working. The listing has photographs of where all of it landed on the case.

Written by Onion Madder. The echo modification is Darren C. Shaw's work, credited and linked above.