Dilshan R Jayakody’s Web Log

If you are an audio enthusiast and if you have multiple audio systems and speakers, you may definitely need to have a speaker selector switch. These switches allow you to route a audio signal through a switching system and distribute it to various speakers. Using this listener can select single amplifier – speaker combination through the switch. We mainly design this switch to share our speaker system with multiple audio amplifiers. We design this switch to handle 6 stereo audio channels. Final view of 6 channel speaker selector prototype. This switch is based on PIC16F88 - 8bit MCU, ULN2803 Darlington transistor arrays and 12 DPCO relays. MCU is the core component of this switch and it control all relays, seven-segment display and store last channel in E 2 PROM memory and restore it during next power-up. In this system all audio lines are switching using 12 DPCO relays. To get optimal results we recommended to use good quality relays with thus switch. In our prototype we u...

When working with an expensive speaker system, speaker protector is an essential item to avoid any damages to speakers. In this project, we build a 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 the 24V relay. Prototype version of μPC1237 - 2 channel speaker protector system. PCB design of this project is limit to 90mm × 43mm and based on through-hole components. Depending on the supplied voltage and relay, the value of R7 resistor is needed to be changed. The specified value in the schematic is for 24V AC power source and for Omron 24V G2R-2 relay. Start-up delay of this unit can be adjusted by changing the values of R5 and C5. Schematic and PCB design files of this project are available to download at google drive .