Pitch Control For Cd Players

photo detector (optical pick - up) tracking servo pow2„../ _supply 01-D4 GND LO LM HE in - focus servo z r:disc - motor servo BBB 1111 1 hTirTT DRAM DD v a) in the absence of a headphone output ± 5V is adequate ozv• -ize 2z• E ..., servo circuits PITCH CONTROL FOR CD PLAYERS In general, only professional compact-disc players are provided with a pitch control. Domestic types so equipped are few and far between, and are also pretty expensive. A circuit is described here that makes it possible for a pitch control to be added to most CD players at a fraction of the cost of a professional unit. Correct operation of a CD player is en- sured by a central, crystal-controlled clock operating at 11.2896 MHz. In the block diagram of a typical CD player- see Fig. 1-this clock is contained in the digital filter chip (SAA7220), but the crystal is external to this IC. The clock controls not only the data processing, such as decoding, error correction, and digital-to-analogue conversio...