R1 may be 10k and R2 100k. The transistor can be the BC548 and instead of the small lamp we can use a series LED with a 1k resistor. D1 is germanium and C1 is 10 nF. C2 can be 47 nF.
This circuit was found in a 1995 documentation. It drives a set of sequential LEDs from the sound...
This circuit was found in a 1968’s publication and uses germanium transistors. Equivalents can be...
The integrated circuit used is equivalent to the 555 and the transistor can be the BC558. R1 and...