This amplified speaker is from a Radio Electronics from September 1988. The power integrated circuit is from that time and the other components are still common today.
This circuit can function as a light alarm by changing the sound when light falls on the sensor....
In this circuit the photo-transistor signal is amplified by a Darlington step and then applied to a...
This is a traditional complementary-output transistor amplifier sourcing 2 to 4 watts to a 4 ohm...