The transistor output Z is to high to feed a speaker or headphone. One way to overcome this is to raise the collector current. A higher current will reduce the output Z but it cost power. I want a battery powered set that will not drain the battery to quickly. A BF2040 stage will feed a 50 Ohm load with 10ma current drain. I want to try and do a little better than that. We could use an output transformer but I want to use parts available off the shelf. While winding a transformer is not extremely difficult is not beginner level. I need 1 mv to drive my earbud. This circuit works faily well.
My favorite hearing aid amp is very good but it requires transformers.
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