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.
The components used in this National Semiconductor circuit are not common today, but the...
This 2001 circuit is used with transceivers to increase the gain of a microphone and thus obtain...
In the figure we have the configuration of a variable voltage regulator with two transistors and a...