The capacitor used in this circuit can have values between 5 and 30 uF. The circuit is of old documentation for radio amateurs. Observe the special source used in the supply.
This circuit was published in a 1977 English magazine, but it can be easily assembled since all...
This circuit, from a 1988 documentation, consists of an automatic temperature control using an NTC...
Figure bellow shows a ring oscillator using five inverters of a 4049. [The circuit operates only...