This circuit uses components that are still common despite being from 1995 documentation. The circuit can be powered by 6 to 12 V voltages and the speed of the LEDs' sliding effect is set to P1.
This PNP transistor power stage was found in the May 1969 issue of Radio Electronics magazine. The circuit...
Apart from the speaker, this amplifier uses only 3 components: two transistors and a resistor....
We found this circuit in the 1960 Mullard transistor reference manual. The phototransistor can be a...