Please read the description/textbox first. Circuit of a mini headphone Class A amplifier that works on Voltages between 3 Volt and 1.9 Volt. Thus also works when the two 1.5 Volt batteries in series (= 3 Volt) get very much depleted, say to 1.9 Volt.
It is a Class A amplifier. The constant current that it takes varies regarding the Voltage status of the 3 Volt battery source. Fierce or depleted.
When that voltage goes down from 3 Volt to 1.9 Volt, the current drops down to a very low level. Thus a very small current is drawn at 1.9 Volts.
It means that even with depleted batteries it keeps on working. Of course: not always, but the circuit has a quite good endurance.
Everything about the schematic is told in the video. The 2200 uF capacitor in the schematic also prevents the so called “motorboating” when the batteries get extremely depleted.
I tried to explain that again in the video, though that 2200 uF capacitor is or was probably enough.
That 2200 uF capacitor also is a kind of help when the batteries (2 x 1.5 V =3 Volt) get exhausted. Acts as a kind of buffer and stabilizer.
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Some persons try to find gold via my circuits. I take distance from all these fake claims. I cannot help that these things happen. Upload 16 July 2022.