Circuit-bending a Funky Furby #5: switches

Working directly on the circuitboards to find glitches was very difficult, especially since most actions involve, well, action and the Furby kept moving around.

Not a particularly effective solution...

Not a particularly effective solution...

Removing the feet again allows the Furby to stand fairly steadily on the base of the battery compartment without the leg cams reaching the surface it’s on to make the body move. However, this also means you have to down tools and pick the Furby up each time you need to turn him onandoffagain. With all the exposed mechanics and electronics, finding a safe place to pick him up by is a challenge in itself.

On-off switch

The on-off switch doesn’t appear to be directly connected to the battery compartment as in simpler electronic toys I’ve worked with, instead 3 wires come out from the back of the switch and join onto the circuitboard.

snipped wires from on-off switch

snipped wires from on-off switch

I just snipped the yellow, red and green wires about an inch away from the switch (enough to leave me room to solder back onto the wires going into the switch, if needed) and then extended the wires connected to the circuitboard and soldered a SPDT toggle switch onto the other ends.

Extensions to the on-off switch wires

Extensions to the on-off switch wires

Tickle me

I also wanted to add remote switches to the belly, mouth and back of the Furby. All these plug into the circuitboard and, thanks to the coloured wires, are reasonably easy to identify.

Wires from switches; old and new

These are actually connections for LEDs (see later) but the principle is the same for the switches

It’s also pretty straightforward to solder a couple of extra wires onto the leads of the plugs where they come out onto the front of the circuitboard. I’m just using some momentary push-to-make switches to trigger the Furby. It’s nice to have a few actions that are not in response to voice commands.

Audio jack, glitch switch and back trigger

Audio jack, glitch switch and push buttons for belly and back

I also tried to use a push-to-make switch to control the sound glitch, but found I was killing a lot of switches in the process. At first I thought I was over-heating them at the soldering stage and messing up some of the internal contacts, but I eventually noticed (with the help of my multimeter) that it was after a few pushes that the switch stopped working. I thought that the current might be too high for the switches and so added in a 10ohm resistor, but was still getting sketchy results.

Increasing the resistance had the effect of speeding up the sound (not particularly desirable) so rather than increase the resistance I eventually abandoned the push-to-make switches in favour of a chunkier toggle switch (also with 10 ohm resistor).

At one stage I tried a large latching push-to-make switch, but I struggled with this because it was never clear whether it was on or off. If you’re going to go down this route, I suggest maybe using one with an indicator LED…

All-in-all there’s now a significant number of wires coming off the Furby and the solder points are quite delicate – particularly those ones that connect directly to the circuitboard. In order to add some protection against accidental pulls, I tied a piece of nylon cord to some of the plastic structure of the Furby and added a few polymorph figure-of-eights. I then looped each wire through the figure-of-eights before then taking it to the switch box. The nylon is slightly shorter than the length of the wires and tied off inside the switch box so it should hopefully take the brunt of any excess force.

Cord stay to protect wires from being pulled off

Cord stay to protect wires from being pulled off

The switch box: main on-off switch and audio jack, glitch toggle switch and 3 buttons for belly, mouth and back triggers

The switch box: main on-off switch and audio jack, glitch toggle switch and 3 buttons for belly, mouth and back triggers

Flashy lights

I’ve also attached a few LEDs to various points on the circuitboard (again, the solder points on the other side to where plugs attach). These were initially soldered straight onto the board, but have now been added onto wires in series with a 1k ohm resistor.

Initial (temporary) location of LEDs

Initial (temporary) location of LEDs

As I write this, the LEDs have made it to the ends of his ears and mohican spikey thing, but I’m not quite satisfied with the result. More tinkering required – perhaps either to add more LEDs down the length of the ears, or to add some sort of translucent cover.

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