When working with expensive speaker system, speaker protector is an essential item to avoid any damages to speakers. In this project we build low cost speaker protector by using NEC's μPC1237 IC. The circuit in this project is based on μPC1237 datasheet and it is specifically modified to work with 24V AC power source and with 24V relay.
PCB design of this project is limit to 90mm × 43mm and based on through hole components. Depending on supplied voltage and relay, value of R7 resistor is need to be change. The specified value in schematic is for 24V AC power source and for Omron 24V G2R-2 relay. Start-up delay of this unit can be adjust by changing the values of R5 and C5.
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