Power Supply Design 159driver transistors. This eliminates the distortion that might otherwise arise because
of breakthrough of signal components from the output transistor supply rail into the
low power signal channel. Similarly, use of a separate supply system for each channel
eliminates any power supply line-induced L–R cross talk that might impair stereo image
positioning.
5.13 Battery Supplies ....................................................................................................
An interesting new development is the use of internally mounted rechargeable batteries
as the power supply source for sensitive parts of the amplifi er circuitry, such as low input
signal level gain stages. Provided that the unit is connected to a mains power line, these
batteries will be recharged during the time the equipment is switched off, but will be
disconnected automatically from the charger source as soon as the amplifi er is switched on.
5.14 Switch-Mode Power Supplies ...............................................................................
Switch-mode power supplies are widely used in computer power supply systems and
offer a compact, high effi ciency regulated voltage power source. They are not used in
hi-fi systems because they generate an unacceptable level of HF switching noise due to
the circuit operation. They would also fail the requirement to provide high peak output
current levels.
Reference ..............................................................................................................
- Linsley Hood, J. L., Wireless World , 43–45, January, 1975.
- Linsley Hood, J. L., Electronics Today International , 24–31, June, 1984.