This symmetrical power supply uses two old filament transformers. The circuit was obtained in a documentation from the 80's and the diodes can be 1N4002.
This circuit was published in an English magazine from 1980. The magazine no longer exists, but...
Found in a 1990s Motorola documentation, this high voltage circuit uses a PUT that is not a common...
This proximity sensor was found in a 90s Popular Electronics. The base is a PLL567 that operates...