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 sensitive electroscope uses a MOSFET 3N128 and can detect electrostatic charges of objects....
This three-chanel remote control transmitter uses a unijunction transistor as low frequency...
This relay circuit with a dual channel MOSFET (not very common today) was found in an old American...