A covox was a pre-adlib/sound blaster, cheap device that plugged in the parallel port and was released around at the end of 1987, before people massively adopted the adlib at first, then the sound blaster for their sound and music gaming needs. It provided low quality audio signals that occupied a sizeable chunk of the CPU, but sounded way better still than the default option that many people had back in those early days, the PC speaker with its even more primitive DAC. This would be ideal for early laptops with no room for an ISA sound card, but equipped with the obligatory parallel ports, before other more modern options came along and gave adlib FM synth small PCB through the same port.
I just stumbled upon a facebook post of someone building a 2016 SMD version of that thing. My eyes were looking for a DAC, an opamp chip or anything, but it's just a resistor network and capacitors. I guess I didn't immediately think that an analog signal can come out of the printer port (never messed with tinkering with those) to handle the needed periodic signal for musical tones.
More info here about the Covox: https://en.wikipedia.org/wiki/Covox_Speech_Thing
Simple version github: https://github.com/yeokm1/pcb-covox
Simple version on PCBWay: https://www.pcbway.com/project/shareproject/Covox_Speech_Thing_Sound_Card_SMD_version.html
More complex version with LM386 subcircuit for amplification: https://github.com/yeokm1/pcb-covox-amp/
I just stumbled upon a facebook post of someone building a 2016 SMD version of that thing. My eyes were looking for a DAC, an opamp chip or anything, but it's just a resistor network and capacitors. I guess I didn't immediately think that an analog signal can come out of the printer port (never messed with tinkering with those) to handle the needed periodic signal for musical tones.
More info here about the Covox: https://en.wikipedia.org/wiki/Covox_Speech_Thing
Simple version github: https://github.com/yeokm1/pcb-covox
Simple version on PCBWay: https://www.pcbway.com/project/shareproject/Covox_Speech_Thing_Sound_Card_SMD_version.html
More complex version with LM386 subcircuit for amplification: https://github.com/yeokm1/pcb-covox-amp/
