A circuit for generating the test signal is given in

fig. 19.

The load network consists of a 40

µF capacitor, in

series with a 1 ohm resistor. The capacitor limits

the current due to the 20 Hz signal to a low value,

whereas for he short pulses the effective load im-

pedance is of the order of 1 ohm, and a high out-

put current is produced.

Using this signal and load network the measure-

ment may be made without causing excessive

dissipation in the amplifier. The dissipation in the

1 ohm resistor is much lower than a rated output

power of the amplifier, because the duty-cycle of

the high output current is low.

By feeding the amplifier output voltage to the X-

plates of an oscilloscope, and the voltage across

the 1 ohm resistor (representing the output cur-

rent) to the Y=plates, it is possible to read on the

display the value of the maximum instantaneous

output power.

The result of this test applied at the TDA 2050 is:

PEAK POWER = 100W typ

Figure 19: Test circuit for peak power measurement

TDA2050

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