A push-pull oscillator
Electronic

Once you finish the wiring connections, hold S1 down and listen to the sound from the speaker. Notice how feedback comes through the 0.047µF and 0.1 µF capacitors connected to the transformer's coil.

But see how each capacitor is connected at the ends of the transformer's coil. This means that when one capacitor is charging, the other is discharging. And this means...

...that when one transistor is off the other is operating. There's always one transistor operating.

Since the 0.047µF and 0.1 µF capacitors control circuit operation, try using different values of capacitors in their place.

Since the 47K and 22K resistors control the base-to-emitter current, try using different values in their place and see what happens. Be sure to keep notes of what you discover. What effects do higher and lower values have upon operation?

You'll find this information handy when you start designing your own oscillator circuits.