The Ocean Box simulates the sound of ocean waves on a beach with electronic white noise (and no crying sea gulls). A bonus feature provides pot-adjustable times for rise and fall of the waves. I mainly use headphones for white noise which is very directional. I tested a TDA7297 module with desktop speaker. It has more than enough power but 15khz is down 3db and that is not satisfactory.
Maxim DIP-8 DS1804-50 is an important component of the OB. It is a digital potentiometer with an analogue resistor array of 50k in 100 steps. The stepping is controlled by an Adafruit Metro Mini 328 which is an enhanced version of the original Arduino UNO, without the awkward footprint. Three GPIO are required for the DS1804 control and two GPIO to read the rise-time and fall-time pots. Therefore, almost any MCU could be used. For example, PIC12F675 shown here generating white noise could also be programmed for application control.
I reviewed electronic white noise in "Testing White Noise Generator Devices". I selected the PIC12F675 (from Electric Druid of Portugal) rather than abused transistors because the PIC has a deterministic signal level unlikely to blow the DS1804 input pins. I do not use opamps because gain is not needed. A buffer transistor is sufficient to protect the DS1804.
A Triad WAU12-200 powers the Ocean Box.
Maxim DIP-8 DS1804-50 is an important component of the OB. It is a digital potentiometer with an analogue resistor array of 50k in 100 steps. The stepping is controlled by an Adafruit Metro Mini 328 which is an enhanced version of the original Arduino UNO, without the awkward footprint. Three GPIO are required for the DS1804 control and two GPIO to read the rise-time and fall-time pots. Therefore, almost any MCU could be used. For example, PIC12F675 shown here generating white noise could also be programmed for application control.
I reviewed electronic white noise in "Testing White Noise Generator Devices". I selected the PIC12F675 (from Electric Druid of Portugal) rather than abused transistors because the PIC has a deterministic signal level unlikely to blow the DS1804 input pins. I do not use opamps because gain is not needed. A buffer transistor is sufficient to protect the DS1804.
A Triad WAU12-200 powers the Ocean Box.
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I designed and built a similar project in 1990. I used 74LS TTL. Just now, I dug it out of the closet - it still works! http://www.edgrochowski.com/electronics-museum/ocean.html
If I had to create the same functionality today, I would write a software synthesizer, run it on a PC, and play the sound through a genuinely good audio system.
Ed
If I had to create the same functionality today, I would write a software synthesizer, run it on a PC, and play the sound through a genuinely good audio system.
Ed
