Circuit Project Electronic

care must be taken to ensure that R5 and RV2 are adequately rated. The current through these components is slightly greater than the sum of the output transistor base currents. The output transistor base current is the output transistor quiescent collector current (Ic) divided by the current gain (Hfe) of the device. The current through R5 and RV2 is therefore approximately equal to 4 x Ic / Hfe and this should be calculated for the chosen output transistor quiescent current and output transistor type. It is recommended that output transistors with a gain of 100 or more at the working collector current are used in this design to reduce the power rating requirements for R5 and RV2.

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