After a lot of experimentation and some frustration I feel like I am beginning to wrap my head around the Speak and Spell’s operation. This is by far the most complex toy I’ve attempted to bend and as such there has been something of a learning curve as I explored the circuit and began manipulating it. That being said because this is such a popular toy for circuit bending I’ve been able to find a wealth of information to supplement my own experimentation and give me direction as I delve into this project. Today I’ll take you through the addition of a pitch bend up knob and a hold switch to my Speak and Spell.
For the pitch up bend I actually used three points, I initially found and started experimenting with the pitch bend using the two points on the board above (The 2nd and 4th pins from the right on the synthesizer chip) but found I was able to get a greater range by connecting the third lug on the potentiometer through a resistor to the point shown on the smaller board on the right side. I used a 100K pot and a 15K resistor though I recommend experimenting with different values until you find what works best for you.
Hold and loop functions can be some of the most fun bends on any device as the allow you to create a constant repeating noise from the device which you can modify or play with in all kinds of ways and from my research into the speak and spell I understand it has a number of these type of bends available. Above is shown the first of these bends I was able to locate. If the switch is flipped while the device is making a noise it will continue to make that noise until it is flipped back down. You can then modify the noise output using the pitch bend.