Covox Speech Thing
The Covox Speech Thing (also known as Covox connector ) was a computer accessory used to output digitized sounds. This is a primitive 8- bit - D / A converter (a R2R network ) in the form of an adapter plug coupled to the printer port of the PC is connected and an analog output so provides.
The circuit was marketed around 1986 for $ 70 each. Since the built-in parts only cost a fraction of the finished connector and the circuit is very easy to set up, Covox connectors were soon built by many hobbyists in various variations - one of them is shown here.
The connector was widespread until the 1990s, as real sound cards were still very expensive at the time. He was also quite popular in the demo scene .
The construction requires the use of precise resistors with a tolerance of ≤ 1%. Due to the use of the printer port, it is not possible to print and output sound at the same time. Conversely, loud creaking and crackling can be heard when printing, as the print data is output as a sound via the Covox plug. Nevertheless, the quality of the Covox connector is far superior to the system loudspeaker and still offers an inexpensive way of giving old computers good sound.