The difference between this circuit and the previous one is that it uses PNP transistors. The circuit is from Radio Electronics magazine from July 1968. The frequency depends on R1 and C1.
This indicator circuit used and game machines (arcades) to indicate that the machine is being...
If the reader still uses silk screen printing tables this is an interesting circuit found in a 1994...
This amplifying step was found in an old American publication. The transistor is made of germanium and...