Overload protection and display circuit, particularly for sound radiators

An overload protective device for processing non-uniform program signals such as speech and music, from a high-power source such as an amplifier means, to at least one high-power electro-acoustic transducer means such as loudspeakers or sound radiators, said device comprising at least one protective circuit, including a first relay therein having a winding and at least one pair of back contacts;

• a first resistor, a rectifier and a capacitor in a first series chain connection:
• the sound radiator being in series with said back contacts, connected in parallel with said first chain connection;
• a reverse-operating Zener diode connected in parallel with said capacitor;
• a first circuit including in series an indirectly heated thermistor and said relay winding, said first circuit also being connected parallel with said capacitor;
• said thermistor including a filament winding connected in series with a second resistor;
• and a second circuit connected in parallel with said first chain connection;
• constituting means for sensing an overload condition at the output of the high-power source, means for temporarily interrupting full load to the sound radiator upon occurrence of the overload condition, means for immediately re-establishing the full load when the overload condition has subsided, and means for providing a predetermined time lag in the activation of at least one of said interrupting and said re-establishing means.