A darlington amifier is not designed for AF amplification due to the temperature drift which shifts the bias. Sometimes the power stages of an amplifier use darlington transistors in a very controlled way by using strong DC feedback.
It’s preferable to use a feedback amplifier stage as the ones I proposed in this forum.
A second disadvantage of the darlington is the uncontrolled gain.
A better solution is to use a very high gain transistor such as the MPS-A18 or the BC549C both having a Hfe gain of 500 when a single transistor stage is preferred.
- This reply was modified 3 years ago by LectronFan.