The circuit shown in the figure can be used to connect a loudspeaker to an amplifier only after the voltages in the circuit are stabilized thus avoiding the crack that, besides being unpleasant, could ruin the loudspeaker itself. The relay should be 50 mA for 6 or 12 V and the current according to the load to be controlled. The delay time depends on the resistor from 100 k ohms to 1 M ohm and the capacitor from 1 to 100 M ohm. The diode in parallel with the relay can be of any type.
