This circuit was found in the November 1974 Radio Electronics magazine. The voltage depends on the supply and the timings of R1 and R2 as well as C1 and C2.
In this phase shift circuit, the transistor can be any general-purpose transistor. The circuit is from...
This amplifier was found in Burr-Brown documentation from the 90's. The gain can be programmed by resistor...
This well-known configuration of the guitar effects pedal was obtained in an English magazine from...