Protect Your Speakers: Soft Start Circuit Diagram

Description

This is a safeguard circuit for speakers, safeguarding against excessive DC voltage potentially arising following damage within a power amplifier. Should a DC voltage appear at the speaker output, the relay RL1 immediately disconnects the speaker line, thereby preventing it from being subjected to unwanted loud noises. In parallel, a time delay of 3 seconds is implemented from the moment the power supply is activated, shielding the speakers from detrimental pops that are observed when the power switch is opened. The LEDs D4 and D5 furnish optical cues regarding the circuit's operation: D4 (green) signifies ‘OK,’ while D5 (red) indicates a delay or the presence of a DC voltage. The circuit's power originates from a dual ±12V supply, obtainable from a separate power supply or derived through subsequent voltage reduction of the main power source. It is advised to construct this protective circuit for each final amplifier you possess. Careful consideration must be given to the quality of RL1, as the contacts are intended to handle the current flowing through it.

Circuit diagram

Part list

TL071

The TL071 is a three-terminal JFET operational amplifier. This integrated circuit is often utilized in low-noise amplifier applications, as well as for instrumentation and general-purpose amplification. The TL071’s primary advantage is its high input impedance, making it suitable for sensitive measurement circuits. It operates over a wide supply voltage range and provides excellent stability. Its specific characteristics make it appropriate for the comparator function within the speaker protection circuit.