Published January 8, 2020 © CC BY-NC-SA

WiFi Controlled Audio Source Selector Switch (Wi-CASSS)

This WiFi module makes it convenient for the user to switch between two audio sources without the need to swap and insert the audio cables.

AdvancedFull instructions provided8 hours7,234

WiFi Controlled Audio Source Selector Switch (Wi-CASSS)

Things used in this project

Software apps and online services

Blynk

Hand tools and fabrication machines

Soldering iron (generic)

Solder Flux, Soldering

Solder Wire, Lead Free

Holder, PCB

Story

Introduction:

Most of the audio devices used even today, widely adopt the 3.5 mm or the differential audio jacks for the transmitting the audio signals via a cable. Though this concept is changing in mobile devices by shifting towards wireless audio, but most of the bulkier audio devices such as the TV or a bookshelf speakers, still use the wired medium for transmitting audio.

These audio jacks are usually placed at the rear end of the devices which are difficult to reach once they're set-up on a desk or a stand unit. So whenever the user wants to connect a new Audio Device like an iPod or a new set of speakers, the user always has to unplug and re-insert the respective cable for the device. This makes it very inconvenient for the user, especially when the cables have to be frequently swapped in and out.

So in this project I have designed a remote WiFi Controlled Audio Source Selector Switch (Wi-CASSS) which enables the user switch between two connected input/output audio devices over internet. Hence this removes the difficulty of swapping in the audio cables every time one connects a new device.

The Wi-CASSS Module

Design & Working Principle:

The circuit consists of a Double Pole Double Throw(DPDT) Relay which switches the Left & Right Channel of the audio signals into two separate channels. Since relays are just an electromechanical switch, they don't distort the audio signals and most importantly, they are bi-directional. So audio signals can be given from any direction.
For convenience, the whole circuit is powered by 5V which is easily accessible via a USB port.
The DPDT Relay used in this project is OMRON G6S-2 (5V) relay which according to its data sheet, is best suitable for Signal Switching.
For the Wi-Fi module, the requirement was to only switch a single relay which means only one GPIO was necessary. So I went with the 8-Pin ESP8266 ESP-01 module.
Now this Relay is switched ON/OFF (using a transistor switching circuit) depending upon the signal received by one of the GPIOs of the ESP8266 ESP-01.

In order to avoid distortions in the audio signals, the ground pin of the audio devices connected are ISOLATED from the ground pin of the 5V USB power source.

Components Needed:

1x ESP8266 ESP-01 Wi-Fi Module
1x OMRON G6S-2 (5V) DPDT Relay
2x 3.5mm Male Audio Jacks
1x 3.5mm PCB Mountable Female Audio Jack
DC Jack (2-Pin) For USB Power (5V)
2x 1N4007 Diode
2x LEDs (Different Color. One for Power Indicator & the other to indicate Relay State)
2x 330ohm, 1x 1Kohm, 1x 10Kohm - 1/4 watt resistors
1x BC547 NPN Transistor
Small Size Perforated Circuit Board
1x 1uf, 1x 10uf Capacitors
6pin Polarized Header Pin Connector Set.
Female Header Pin for Mounting ESP8266
1x AMS1117 3.3V Fixed Voltage Regulator

Fabrication Steps:

Check out the Circuit Diagram and place the components on the circuit board in such a way which would require the least amount of soldering traces. After finalizing, start soldering.

Placing of components

Now cut down 2x - 4pin female headers for the ESP8266. Verify the connections for the ESP8266 and mark its corresponding pins with a colored marker for convenience like on the image and start soldering. NOTE: ESP8266 works only on 3.3V. Hence it should only be connected to the 3.3V regulator pin.

Marking 5V rail, 3.3V Pin, Ground Pin, GPIO Pin on the circuit board.

At last mount the 3.3V AMS1117 Fixed Voltage regulator and complete the soldering.

After completing the soldering process and making connection traces.

Connect the 6 pin polarized header pin to the 2x 3.5mm male audio jacks as shown below.

The 6pin polarized connector is connected to two 3.5mm male audio plugs.

Programming the ESP8266 ESP-01:

The Arduino IDE installed in your PC must include board manager data for ESP8266. After that use a Serial to USB converter for programming your ESP-01. In my case I used an Arduino NANO to program the ESP-01.

An Arduino NANO being used to program the ESP8266 ESP-01 module.

Setting Up BLYNK Application in your Mobile:

In your mobile, install the Blynk App from the Play Store or App Store and create an account.
After creating an account, click on create a new project with board selected as ESP8266. Then you will get an authorizing code in your email. Keep the code copied in your clip board.
Now create a button as shown in the image below and select the pin number of GPIO.

Setting up the button widget on Blynk Application.

Now install the Blynk Library on Arduino IDE and take the example code of Standalone WiFi or take the attached code in this project. In this code, modify the Network Name SSID to your corresponding home network name and add the password on the next line. On the "auth token" space, paste the authorization code which you received from the email for the project and finally click on RUN.

Testing:

I connected an iPod and an iPhone as two source inputs to the Wi-CASSS. For the output I attached a 5-Watt 2.0 Channel Speaker.
The iPhone itself was used to operate the Blynk application.

Then Audio was played simultaneously in both devices and the speaker provided output only for one of the device depending upon the selection made on the Blynk application.

Testing

LEFTImage (1)- The audio source is selected from the iPod and hence the relay is inactive and the Green LED is off.

RIGHTImage (2) - The source is now switched from iPod to iPhone in the Blynk App and the speaker is now providing audio output from the iPhone only. So now the Green LED is turned ON and the Relay remains active.

Conclusion:

Using WiFi controlled switch provides more range of distance for switching (If internet is connected, the Wi-CASSS can be switched from anywhere around the world) and makes it easier to control via smartphone.

Depending upon the requirement, the user can replace the WiFi module with an IR Remote Control or Bluetooth Module, and mount it over the same Audio Switching Relay Circuit.

THANK YOU!

Code

ESP8266 ESP-01 Blynk Code

#define BLYNK_PRINT Serial


#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "YourAuthToken";

// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "YourNetworkName";
char pass[] = "YourPassword";

void setup()
{
  // Debug console
  Serial.begin(9600);

  Blynk.begin(auth, ssid, pass);
}

void loop()
{
  Blynk.run();
}

Credits

Govind

1 project • 1 follower

I am an electronics hobbyist & and a Do It Yourself Enthusiast.

WiFi Controlled Audio Source Selector Switch (Wi-CASSS)

Things used in this project

Software apps and online services

Hand tools and fabrication machines

Story

Introduction:

Design & Working Principle:

Components Needed:

Fabrication Steps:

Programming the ESP8266 ESP-01:

Setting Up BLYNK Application in your Mobile:

Testing:

Conclusion:

Schematics

Circuit Diagram

Code

ESP8266 ESP-01 Blynk Code

Credits

Govind

Comments

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WiFi Controlled Audio Source Selector Switch (Wi-CASSS)

WiFi Controlled Audio Source Selector Switch (Wi-CASSS)

Things used in this project

Software apps and online services

Hand tools and fabrication machines

Story

Introduction:

Design & Working Principle:

Components Needed:

Fabrication Steps:

Programming the ESP8266 ESP-01:

Setting Up BLYNK Application in your Mobile:

Testing:

Conclusion:

Schematics

Circuit Diagram

Code

ESP8266 ESP-01 Blynk Code

Credits

Govind

Comments

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