This is a high quality audio class AB amplifier in hi-fi applications. It has very low noise and distortion, wide bandwidth and good output current capability, enabling it to supply high power into both 4Ω and 8Ω loads. It has both short circuit and thermal protection, so is quite robust.

Component part list:

R1_____________ 150R
R2, R3, R5_____ 10K
R4_____________ 680R
R6_____________ 22K
IC1____________ TDA 7294
Heatsink

C1____________ 1u5F or 1u
C2____________ 2n7F
C3, C6________ 22uF 63V
C4, C5________ 10uF 63V
C7, C9________ 2200uF 50V
C8, C10_______ 100nF

AC adapter basics:
It seems that the world now revolves around AC Adapters or ‘Wall Warts’ as they tend to be called. There are several basic types. Despite the fact that the plugs to the equipment may be identical THESE CAN GENERALLY NOT BE INTERCHANGED. The type (AC or DC), voltage, current capacity, and polarity are all critical to proper operation of the equipment. Use of an improper adapter or even just reverse polarity can permanently damage or destroy the device. Most equipment is protected against stupidity to a greater or lessor degree but don’t count on it. The most common problems are due to failure of the output cable due to flexing at either the adapter or output plug end. See section below on repair procedure.

1. AC Transformer. All wall warts are often called transformers. However, only if the output is stated to be ‘AC’ is the device simply a transformer. These typically put out anywhere from 3 to 20 VAC or more at 50 mA to 3 A or more. The most common range from 6-15 VAC at less than an Amp.