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 E2PROM memory and restore it during next power-up.
In this system all
audio lines are switching using 12 DPCO relays. Listener can change
channel by pressing the (J2) push button. To disconnect / mute the
channel, hold down J2 push switch for 5 – 10 sec.