Connecting a loudspeaker to a DC coupled amplifier without adequate protection can lead to failures that could destroy the loudspeaker and also pose a safety hazard to the user as its coil could overheat and start a fire.
The SP-DR1200 loudspeaker protection system allows an activation with a delay greater than or equal to 3.9 seconds (this time can be easily modified) as well as a disconnection of the loudspeakers used by the CDS-4700 amplifier with a time not greater than 13 milliseconds (without considering the stabilization of the relay in use).
Its operation is based on a first-order low-pass filter with an approximate cutoff frequency of 0.067 Hz and a comparator with a detection level no greater than ± 2V. Its design is achieved by discrete circuitry, which allows the operation of this board with a wide range of positive and negative voltages, from ± 18V to ± 35V.
The SP-DR1200 board is equipped with two channels to build a stereophonic system. Also, the PCB is prepared to accept two types of footprint for different relays.
The following are the main operating characteristics of the SP-DR1200 board:
- Relay activation at 12V or 24V
- Double footprint for different relays
- Normally open relay operation
- Power-up activation of 3 to 4 seconds to avoid thumps and other noises
- Disconnection time of 13 milliseconds when the power supply is switched off
- Approximate disconnection time of 28 milliseconds in the presence of an offset voltage in the output signal
- Relay on/off indicator LED
- Total harmonic distortion equal to 0.000097% @ 1 kHz and 2.47 Watts dissipated into an 8.3Ω resistive load. Tianbo HJR-3FF-S-Z relay driven at 12 Volts
- Total harmonic distortion equal to 0.000093% @ 1 kHz and 1.9 Watts dissipated into an 8.3Ω resistive load. Goodsky GZ-SS-112L relay driven at 12 Volts
- Detection is done with negative and positive levels
- Use of terminal blocks to facilitate interconnection with the CDS-4700 composite amplifier board output terminals
The PCB material used is FR-4, double sided, 1 oz. copper and the board thickness is 1.6 mm. Its approximate dimensions are: width = 6.6 cm, length = 10 cm and has a lead-free HASL type surface finish. It uses through hole technology for easier component assembly.
The published price is for the PCB only. Bill of materials and instructions are sent upon purchase.