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.
With this simple tester you can measure the gain of an NPN or PNP transistor. The instrument can...
I found this circuit in an old Argentine publication from 1973. The components are no longer...
Used with telephones at the time, this circuit was found in Popular Electronics from the 90s. The...