Commonly used audio circuits for color TVs: TDA1521

This circuit is taken from Changhong C2191 and is an OTL two-channel connection method.

TDA1521 pin function and reference voltage:

Pin 1: 11V - reverse input 1 (L channel signal input)

Pin 2: 11V——Forward input 1

Pin 3: 11V——Reference 1 (0V when OCL connection, 1/2Vcc when OTL connection)

Pin 4: 11V - Output 1 (L channel signal output)

Pin 5: 0V - negative power input (grounded during OTL connection)

Pin 6: 11V - Output 2 (R channel signal output)

Pin 7: 22V - positive power input

Pin 8: 11V - forward input 2

Pin 9: 11V - reverse input 2 (R channel signal input)