AVT 3233 Mounting Diagram & Instructions

Symmetrical Power Supply
kits for Audio Amplifiers
Amplifiers over a dozen watts require a power
supply that provides two voltages (i.e., symmetrical
voltage). This circuit is a simple power supply,
allowing it to work with audio amplifiers up to
100 W. The unit can complement a self-built audio
system. It allows to make a non-stabilised power
supply with a maximum output current of up to
6 A.
Circuit description
Schematic diagram of the device is shown in Figure 1.
This power supply is a simple two-voltage rectifier.
Two alternating, symmetrical secondary voltages of
the transformer with opposite phases obtained from
the two windings connected in series are applied to
the connectors AC1, AC2 and
GND of the power supply, and then go to Graetz
bridge made up of rectifier diodes D1-D4, where they
are two half rectified and smoothed by electrolytic
capacitors C5-C7 for the positive supply line and C8-
C10 for the negative line. This results in a positive
voltage at the output of the power supply and a
negative voltage relative to the GND of the circuit.
The 1N540x diodes are provided in the unit. Each
diode can rectify a current of up to 3A, and as there
are two diodes working in pairs in the bridge, the
maximum output current of the power supply is 6A. It
Features
• designed to power audio amplifiers up to 100 W
• symmetrical voltage supply
• integrated filter capacitors
• integrated rectifier bridge
• connection - screw terminals
• maximum transformer voltage 2×34 VAC
• board size 40×96 mm
is worth knowing that the specified value of 3A refers
to the rectified current, while the maximum current
pulse of 10 ms duration (one half-period of the
network) for the 1N5408 diodes can have as much as
200 A. The amplifier, with a continuous (sinusoidal)
output power of 1×200 W operating with an 8 Ω load,
draws just over 5 A of current at full drive. However, an
amplifier with an actual output power of 50W draws
just over 2.5 A, hence a 2×50 W stereo amplifier will
draw over 5 A at its peaks. With a 4 Ω load, a single
100 W amplifier draws more than 5 A. While a 2×50 W
amplifier with a 4 Ω load will draw at its peaks more
than 7 A of current. This is a current in excess of the
maximum output current of the power supply,
however, there is an advantage in a power amplifier
circuit because in practice the amplifier never runs
continuously at full, unchanging power. Audio signals
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