This circuit was obtained in an old Popular Electronics. It makes use of quite common components. The speed of the effect is set to R7. The circuit drives 20 LEDs.
This amplifier with complementary symmetry output and good sound quality was found in...
This circuit should be placed between the signal source and the input of a recorder or amplifier....
Found in an Electronics World of 1968 this circuit can use current SCRs and the diodes are...