Adjustable reference (CB21540E)

We found this circuit with 5.3V zener in a Philips publication from the 60s. The op amp could be a modern equivalent.

Astable Timer 555 (CB9369E)
This circuit was obtained in a Hands-On Electronics from the 90's. The circuit turns on one LED at...
Giro Counter (CB19870E)
This circuit makes use of an integrated LM2907. The circuit is from an old documentation being...
Unijunction Dimmer Simulated (CB23966E)
This circuit simulates a unijunction transistor with two bipolar transistors. We found it in the...