This high impedance headphone amplifier was found in American documentation from the 1990s. Any general-purpose FET can be used.
This is yet another simple LED driving game circuit that appears in several other versions on this site....
We found this circuit in a manual of optoelectronics from Texas Instruments. In it photodiodes or...
This interesting circuit is from a 1988 documentation. It is a matrix of diodes that converts...