This is the circuit of the commercial Japanese megaphone of the 60s model DM-218. The circuit uses a compression speaker (horn) and is powered by 4 large batteries. The output power is 2 W.
This circuit causes an LED to flash at a frequency determined by the capacitor. The circuit has an...
Found in American documentation from the 1980s, this circuit uses transistors from that time. It...
This very interesting project was obtained in a 1980 publication. It consists of a device that is...