December 31, 2022 by Dilshan Jayakody
A DIY six-channel stereo speaker selector to share a pair of speakers between six stereo audio systems.
This project is a DIY six-channel stereo speaker selector based on STC15W201 MCU. The purpose of this electronic switch is to share a pair of speakers between six stereo audio systems. This is an improved and low-cost version of the 6-channel speaker selector which we developed a few years ago.
This new speaker selector uses STC15W201 MCU. This MCU is a low-cost 8051 MCU designed by STC micro. At the time of this writing, the STC15W201 can obtain for less than US$ 0.8. To drive the seven segments and to control the relays, this design uses the popular 74HC595 8-bit shift register ICs.
PCB of the 6-channel speaker selector.
To select each speaker channel, we use pair of 12V DPDT relays. These relays interface to 74HC595 through a ULN2001D 3-channel Darlington transistor array IC. This 3-channel Darlington driver IC is functionally equivalent to the famous 8-channel ULN2003 IC. This ULN2001D version is an 8-pin IC and is available in both DIP-8 and SOP-8 packages.
This new board is designed to work with a 12V DC power supply and in our prototype build, we use a 12V/5A SMPS unit to power the whole system.
To get the optimal results with this circuit, use an Omron G2R-2-12DC or an equivalent type of relay with a coil current lower than 100mA.
The functionality of the firmware is almost identical to the old PIC16F88 firmware. After powering up the system, the active speaker channel is displayed on the seven-segment display. To switch to a different speaker channel, press the button repeatedly with short intervals.
Finished prototype build.
The PCBWay sponsored this project. PCBWay offers high-quality PCB manufacturing and assembling services. Also, they offer CNC and 3D printing services. The Speaker selector PCB is available to order from PCBWay. Check out the PCBWay website for its manufacturing capabilities and pricing.
The PCB design, schematic, and other design files of this project are covered with a CERN-OHL-W 2.0 license. Firmware source code is released under the terms of the MIT license.
