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 1.2 to 32 V x 3 A regulator was found in an 80's EDN. The power components must be equipped...
This is a typical common emitter amplifier stage configuration. The transistor can be used...
This configuration was found in a publication for radio amateurs in 1975. It is a signal strength...