As part of a uni project i decided to take it upon myself to create a simple DIY Synthesiser based off a standard toy keyboard, routed through various circuits in order to modify the sound. In this case i opted to use existing circuitry within guitar pedals as i'm not by any means a competent circuit builder.
Step 1: Components / Materials
For this particular project a single keyboard and only two guitar pedals were utilised, although the amount of additional circuitry is completely optional.
The components / Materials required for this project were as follows:
-Functioning keyboard (Preferably sample based).
-Additional Circuitry in which you'd like to incorporate.
-Sheet of moderately thick ply and additional scrap wood may come in handy.
-1/4 Inch output Jack
-Suitable length wood Screws (between 15mm & 30mm)
-Drill (Including both drill bits to match screw size & screw attachment)
Step 2: Construction
In terms of construction, the process depends highly upon the desired aesthetic, and what is physically possible with the components you have. In this case i opted to create a plywood case in order to house the additional components, as the original didn't have enough real estate.
-Remove original keyboard and components from keyboard, measure required dimensions and then size your plywood case construction suitably. In this case i kept the case design simplistic, construction a very basic but functional rectangular prism.
-Decide which controls from the original instrument you'd like to remain, and discard the rest. For simplistic purpose i'd suggest removing anything unnecessary and gimmicky, in this case i only retailed the sample bank, volume, sustain and vibrato controls.
-Attach keyboard as necessary within casing, layout positioning of original keyboard circuitry and begin placing additional circuitry. In this case i utilised cheap distortion and flanger pedals purchased of gumtree, suiting the job nicely.
-Once layout is determined begin cable routing. Beginning with finding a suitable output from the keyboard circuitry, in this case i soldered a 1/4" TRS jack to the original speaker connection, then routing this via 1/4" leads through the guitar pedals.
-Once all connections are made and ensured to be functioning it's time to create the face plate, in this case i utilised plastic sheeting as it was easier to cut and shape the necessary holes, although plywood / balsa wood or similar would work just fine. Next cut the material to size, measure and cute the controls in relation to your layout, and mount via as many screws required being sure to pre-drill holes.
-Plug your DIY synth in and you should be good to go. The layout and additional circuitry depends entirely upon what you want to achieve / how much time or money you're willing to address. In my case i was on a budget and under a time restriction, thus leaving me without the chance to fix a few simple things such as mounting the on and in / out-puts on the outside of the case, although this does not affect overall functionality. HAVE FUN!!!