The transistor used in this circuit is uncommon today. AC124 or equivalent such as AC188K and 2N2431 can be used. The circuit is from the 80's and makes use of transformers.
The oscillator shown in the figure can generate signals between 3 and 15 MHz approximately, depending...
Operational amplifier such as the CA3140 or the TL series can be used in this circuit from a 1982...
With the configuration shown in the figure, a single pulse for a counter can be obtained from a...