Salvador12
Full Member level 4
Hello,
So I have taken a existing schematic that I have built already and it works and I decided to modify it for some of the higher power amplifiers that I have because they have DC rails exceeding +-80VDC and I thought that in case of a DC fault in the output the mechanical relay might weld short circuited and so the speakers would get damaged. So I approached the idea of using a solid state relay made from bidirectional MOSFET switches, I replaced the original relay in the schematic with the mosfet's and I plan to use a recently developed MOSFET driver exactly made for this purpose, an IC namely Si8752. It is isolated of course and works based on RF power transfer within the chip instead of the more traditional optocoupler/photovoltaic IC's which are slower to charge and discharge the gate capacitance.
I also added a varistor in the output or one can use a TVS diode or other means to short the output + to GND after the MOSFET switch has disconnected the amplifier output in case of DC fault because due to various filters coils there is expected to be a inductive spike of voltage across the speaker terminals which needs to be dissipated safely in order not to cause breakdown within the MOSFETS by exceeding their safe Uds.
What do you think , can this circuit perform as expected?
I am planning to build one.
So I have taken a existing schematic that I have built already and it works and I decided to modify it for some of the higher power amplifiers that I have because they have DC rails exceeding +-80VDC and I thought that in case of a DC fault in the output the mechanical relay might weld short circuited and so the speakers would get damaged. So I approached the idea of using a solid state relay made from bidirectional MOSFET switches, I replaced the original relay in the schematic with the mosfet's and I plan to use a recently developed MOSFET driver exactly made for this purpose, an IC namely Si8752. It is isolated of course and works based on RF power transfer within the chip instead of the more traditional optocoupler/photovoltaic IC's which are slower to charge and discharge the gate capacitance.
I also added a varistor in the output or one can use a TVS diode or other means to short the output + to GND after the MOSFET switch has disconnected the amplifier output in case of DC fault because due to various filters coils there is expected to be a inductive spike of voltage across the speaker terminals which needs to be dissipated safely in order not to cause breakdown within the MOSFETS by exceeding their safe Uds.
What do you think , can this circuit perform as expected?
I am planning to build one.
