My son recently got his GCSE results – all ‘A’s and ‘A*’s. He outshone my 7 ‘A’s, 2 ‘B’s and a ‘C’ (in Art) that I achieved in my ‘O’ Levels and I’m really proud of him. It got me to thinking about my Electronics ‘AO’ level.
I got an ‘A’ (there were no ‘A*’s in those days) but it always bugged me that my practical project, a speech synthesiser based on the SP0256 speech chip from General Instruments (now Microchip) never worked. I blamed the PCB. It wasn’t a bad first attempt at etching but I had to repair some of the thinner tracks and eventually ran out of time.
After I got my Arduino Uno, I looked around for some projects and came across this gem at http://nsd.dyndns.org/speech/. I still had an SP0256 chip from the 1980’s and a 3.2768MHz crystal, so I set it up on the breadboard and, lo and behold, it worked!
So I was vindicated – it was the PCB at fault, not my software coding.
I went on to design a dedicated circuit on stripboard with an ATmega328P (the processor on the Arduino Uno) and a serial interface, so I could upload code from the Arduino IDE using an USB to Serial converter. Here are some pictures if you are interested: