This is a transistor flip-flop suggested by General Electric in a 1966 paper. The transistors are of the time and can be used equivalents.
This different astable configuration was found in one in a 1974 Ferranti transistor manual....
Alorium Tech XLR8 Application Accelerator & Development Board is an Arduino-compatible board that...
This filter is from the Linear Applications Handbook of the National Semiconductor of 1994....