I had some old Radio Shack/Archer speech processing chips lying around that I’d been wanting to play around with for quite some time. So, I began by bread-boarding them and then designed a PCB layout in Eagle. The chips used are the CTS256A-AL2 and SP0256. The data sheets for these chips are pretty old and hard to read but I was able to decipher enough out of them to get the circuit working.
CTS256A-AL2 data sheets:
- SP0256 Narrator Speech Processor
- Archer SP0256-AL2
I used Eagle to develop a schematic based on the data sheets but omitted the audio amplifier since I was using an external one and couldn’t seem to get satisfactory performance from the circuit used in the data sheets.