This crystal oscillator is indicated for the calibration of IF steps of common radio receivers. The transistor admits equivalent as 2N2222 or BF494. The circuit is from an old American publication.
This circuit was published in Popular Electronics from the 90's. The components are common, as...
This circuit is from a 1982 documentation. It can be modernized using LEDs in series with 470 ohms...
The CMOS 4046 integrated circuit is not very common today, consisting of a very efficient PLL for...