This circuit was found in a documentation of the 80s, having didactic purpose. For R1 values between 10k to 1M can be used. Transistors are general purpose types.
This circuit is from a 1979 publication, using displays of 7 segments of common cathode. The...
This is one of many zero crossing detector that can be found in this section. It was found in...
This circuit can be used in physics experiments, in ionization and in several other applications. The...