White Noise Generator

The one and half year COVID -19 restrictions and limitations created a lot mental problems for the affected by them people - especially the young people were most hit by all these measures. My son also was pained by them. He began to suffer from insomnia. The smallest noise was waking him up and it was unperturbed for him to fall asleep again for hours. We found in the Internet that the white noise can solve the problem in some degree. In the Youtube we found a long videos with recorded white noise played during the whole night. It seems that they worked for him.

Because playing the videos from Youtube during the whole night by the computers is energy consuming, and playing them by smartphone is mobile data consuming, I decided to build a white noise generator. It should be able to connect through Bluetooth to BT speaker, or could be connected through audio cable to the AUX input of some audio amplifier. The creation of this device is described in the instructable.

I decided to use as white noise generator a Zener diode working in avalanche mode. The circuit of the device is attached here. Because I did not want to wait long for the PCB production, I used an existing board which I had available designed for dual opamp. I modified it cutting some paths and bridging some nodes by wires. After finishing the project I created a PCB, which corresponds to the final schematic. It can be ordered or its design data can be downloaded from here.

The opamp used is LM358, but you can use practically each universal dual opamp in S08 package that you have.

To achieve the best results i tried few Zener diodes with different breakdown voltages. For me the best results came with 2V Zener diode. You can by such multiple values Zener diodes here.

The LM358 opamp has quite wide supply range, but I decided to supply the generator with 5V.

Somewhere I had a broken AC/DC USB dual charger - it was only the internal board - its case was damaged and thrown away. I decided to put this module together with the white noise generator in a small plastic box. I cut a ho;es for the USB ports and the power cable. After that I fixed the module with epoxy glue. The WNG board i put near the supply board and soldered its power cables to the DC output of the power adapter. I covered the WNG board with hot glue and over it I put copper band to reduce the EMI To the output of the WNG board I soldered a 3.5mm audio jack connected in mono mode - both channels shorted together. The jack was mounted on the front of the case. After finishing all these operation I closed the box gluing the cover with moment glue.

The design of the white noise generator was completed. Its operation can be seen in the video linked in the top of the instructable.

As seen there it can be used as white noise generator in two ways:

• The white noise generated by the device can be applied to the AUX input of audio amplifier using an audio cable
• A Bluetooth transmitter receiver can be used to connect with a Bluetooth speakers and the white noise can be applied to its transmitters input. The BT receiver/transmitter is supplied directly by the USB port of our device. Such Bluetooth transmitter/receiver can be obtained here.

Of course the such described device can be used also as a simple USB dual charger without inserting the BT transceiver.

Other application - you can use it to transmit music instead white noise from some source without BT function to your Bluetooth speakers. And finally - you can supply the BT transceiver by the device and use its receiver function - in this way adding to your amplifier or speakers Bluetooth functionality.

Thank you for your attention and remain healthy.