This traditional circuit with the 555 was found in a 1984 documentation. In this oscillator, the signal obtained has much greater intensity and can be applied to a speaker or other similar device, such as a low impedance headset. With a supply of 6 V, we obtain a power of approximately 1 W and with a supply of 12 V this power approaches 4 W, so it is necessary to mount the transistor in a good heat radiator. The tone is continuous, and its frequency is adjusted in the pot. For a different range of frequencies, just change the capacitor. For a supply of up to 6 V, medium power transistors with collector currents (IC) typically between 1 and 3 A, such as BD135, BD137, BD139, TIP29, TIP32, etc., can be used. For a 12 V supply, transistors with currents from 6 A, such as TIP41, 2N3055, etc., must be used. The speaker must be 4 or 8 ohms, capable of withstanding a power of at least 10 watts.
