With an 18 V input, this regulator was found in Philips documentation from the 60's. The transistors are from that time. The power transistor must have a heatsink.
This is one of the many approaches we have on the site for this low power 0.5 W amp using the...
This circuit simulates an American siren and can be found elsewhere on this website and section....
This 80's amplifier delivers 6 W of 8 ohm speaker power without using an output transformer....