This circuit is from a Radio Electronics magazine from February 1992. The circuit has the effect speed dependent on C1 and adjusted by R3.
This tuned circuit was found in a 1966 Electronic Circuit Handbook. The transistor can be any...
This TTL circuit has a well-known configuration, having been found in a Radio Electronics magazine...
In the figure we have the way to implement a 5 to 45 V zener diode with 50 mA of maximum current...