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 circuit makes use of a low impedance microphone. The relay is according to the supply voltage...
The astable multivibrator shown by figura 1 has a very low current drain and can be powered from 6...
This step is also suitable for the AC188k and SK3004 transistors and was found in a 1980s...