The timing steps of this circuit are indicated by a 7-segment display. The circuit was found in documentation from the 90s. The capacitor next to the 555 determines the timing steges.
Using components from the era, this 90's EDN circuit is used in analog to digital conversion...
Found in an American publication from the 90s, this circuit allows the supply of 3, 6 and 9 V...
We found this circuit in an old Popular Electronics. The circuit is experimental, driving an LED...