Class-A Multi-purpose Amplifier
The class-a multi-purpose amplifier can be used for anything requiring output power of upto a few hundred milliamps and approx 15 volt swings, in voltage or current drive mode. When in current drive mode true current sampling feedback is used rather than the more common and worse performing pseudo-current drive high impedance output. Of course, the output does not have to be class-a either. The level of quiescent current can be varied by changing the diode string, and with 4 component locations to choose from the range is quite flexible.
As shown, the component values on the voltage drive mode are suitable for a high power line driver or headphone amp, and the component values on the current drive mode are suitable for a loudspeaker test buffer for Thiele-Small parameter measurements (see the 'Articles' page of the website for more information).
PDF of schematic
PDF of copper side of PCB
PDF of component side of PCB
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