Plans to make a tone generator for 1hz to 24hz

atferrari

Joined Jan 6, 2004
4,579
My Siglent function generator seems to be built based on the IC below.

Programming the micro to command it, seems to me the simplest part of this. I would be more worried about the filter required at the output (my stumbling bock at the moment).

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jpanhalt

Joined Jan 18, 2008
11,088
We used to refer to that in college as your plastic pants.

crutschow

Joined Mar 14, 2008
29,527
I would be more worried about the filter required at the output (my stumbling bock at the moment).
The output DAC resolution is 10-bits so there is 1024 steps per cycle and thus, for the lowest 1Hz output frequency, the DAC (step) frequency would be about 1kHz.
Then if you use a 3nd-order LP filter with a corner frequency of about 30Hz at the output, the sinewave should be quite acceptably clean for the desired output of 1-24Hz.
For a 30Hz, 3-pole LP filter (can be done with a single op amp), the 1kHz harmonic would be suppressed by >90dB, which should be well below audibility.
The harmonic (carrier) for the higher frequencies would be suppressed even more.

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Joined Jan 15, 2015
6,548
If I were to consider a project like this I might consider starting with a good or at least OK DDS Function Generator as you can get a relatively good clean sine wave with added features for about $100 USD and actually less depending on what you are willing to settle for. I am not trying to disuade roll your own but by the time it is designed and built on a board with all components and switches getting it right will take some doing. Here's the harder part for me, the left speaker must have a slight difference. Example: Headphones - left speaker is 8hz, right speaker is 8.1hz. That alone is not easy since now we have two channels. The entire concept of 3D sound is amazing and they are getting really good at it with virtual reality. Sub audio I can't speak for. Ron MisterBill2 Joined Jan 23, 2018 11,625 I haven't made many things but want to. I want to create a tone generator capable of binaural sound in the 1 Hz - Delta | Lethargic, 2 Hz - Delta | Deep Sleep, 3 Hz - Delta | Dreamless,4 Hz - Theta | Drowsy, 6 Hz - Theta | Fantasy, 8 Hz - Alpha | Relaxed, 12 Hz - Alpha | Conscious, 16 Hz - Beta | Focussed, 24 Hz - Beta | Active range. Here's the harder part for me, the left speaker must have a slight difference. Example: Headphones - left speaker is 8hz, right speaker is 8.1hz. What am I using this for? My own research to see if what Nikola Tesla and Albert Einstein believed really worked. Basically, this slight shift synchronizes the left and right hemisphere of the brain improving endorphin release, and creating Alpha waves better. Theta waves occur at a lower Hz (see the chart above). If someone can help me create this I would really appreciate it. I'm strictly a beginner electronics enthusiast. At 60 years old, I thought it was time to make this. Thanks! Mike What voltage do you hope to produce, and what sort of load impedance are you feeding the electricity to? And how accurate does the frequency need to be held.That matters quite a bit nsaspook Joined Aug 27, 2009 9,487 No idea what this would do to your brain as an audio signal but the visual is 'trippy'. MisterBill2 Joined Jan 23, 2018 11,625 The device to generate frequencies that low is normally called a function generator. Those low frequencies are seldom called "tones" because of being well below the recognized aurio range of frequencies. So you will need a direct coupled amplifier with DC response. But for such very low frequencies you may do better generating them mechanically, which can provide a lot more power and a true sine wave without much distortion. Consider that 1Hz equates to 60RPM, a speed that is easy to produce with even a cheap DC motor. Alec_t Joined Sep 17, 2013 12,744 No idea what this would do to your brain as an audio signal but the visual is 'trippy'. Since flashing lights in a similar frequency range can cause epileptic seizures in susceptible subjects, I wouldn't be surprised if pressure waves on the ear (its hardly 'audio') could have a similar effect. ebeowulf17 Joined Aug 12, 2014 3,274 The device to generate frequencies that low is normally called a function generator. Those low frequencies are seldom called "tones" because of being well below the recognized aurio range of frequencies. So you will need a direct coupled amplifier with DC response. But for such very low frequencies you may do better generating them mechanically, which can provide a lot more power and a true sine wave without much distortion. Consider that 1Hz equates to 60RPM, a speed that is easy to produce with even a cheap DC motor. Although producing two separate frequencies, deliberately different, but very close to one another, and with the tight tolerances described earlier, might be challenging with cheap DC motors. I'm not arguing against the concept of mechanical generation, but just saying it may not be as cheap and easy if the specs are tight. MisterBill2 Joined Jan 23, 2018 11,625 Although producing two separate frequencies, deliberately different, but very close to one another, and with the tight tolerances described earlier, might be challenging with cheap DC motors. I'm not arguing against the concept of mechanical generation, but just saying it may not be as cheap and easy if the specs are tight. OK, and of course, "cheap" is a relative term. Reading the frequency would be the more complex part of the project. But compare the price of two used DC motors taken from possibly discarded treadmills , and a simple DC supply, and a 100:1 reduction arrangement using belts and pulleys, versus the cost of two function generators, a fairly powerful stereo amplifier with response down to DC, and two of some sort of transducer able to handle that low a frequency, and the cost might look good. shortbus Joined Sep 30, 2009 9,328 The entire concept of 3D sound is amazing and they are getting really good at it with virtual reality. No idea what this would do to your brain as an audio signal but the visual is 'trippy'. Back in my 'partying' days, I bought a cassette tape that had separate sounds for each side of the headphones you had to listen to it with. It didn't work with the speakers. Smoke some illegal herbal substance and listen to the tape and WOW. Talk about trippy. Then there also was a pair of goggles that converted a different tapes sounds to lights flashing in the goggles and it was trippy too, but nothing like the sound tape. Both of these were developed by some psychology lab at some college that I no longer remember and sold in High Times Magazine. SamR Joined Mar 19, 2019 4,132 Sounds like something Pink Floyd would do... MisterBill2 Joined Jan 23, 2018 11,625 Back in 1974, in the sound and vibration lab of a major auto company, they did an experiment with a bucket seat mounted on flexures, and driven by a 100# force capability electrodynamic shaker. Naturally some techs did sit in it as the frequency was swept. At some frequencies the results were impressive as they emptied bowls and bladders. So no clue what if might do if it were just acoustic energy, but I suggest caution, and giving us a full report, after. One more thought, just now, is that a large cavity whistle may be a better way to generate the frequencies. Consider what happens in a car with only one rear-door window open at speeds above 50 MPH. In my car that produces a very uncomfortable pressure pulsation. Like an infrasonic whistle. danadak Joined Mar 10, 2018 4,057 Pretty trivial to do with PSOC, single chip solution. IDE, PSOC Creator, and compiler free. Debug board$ 10 for this.

As you can see most resources, as shown in right hand window, unused, available for other
functions.

Code maybe max 15 lines of code. Waveform out can be standard, sine, square, pulse, tri, saw, or any
arbitrary user waveform.

Regards, Dana.

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Audioguru again

Joined Oct 21, 2019
4,538
Recently on You Tube a very odd sounding video was posted similar to this one. It also has sound frequencies beating together but you hear them. Today I looked for it and found this better one. It has stereo sounds and also see the lissajous display on an oscilloscope in the video. I do not think it makes you sleep and also does not mess up your brain. It is interesting:

MisterBill2

Joined Jan 23, 2018
11,625
Pretty trivial to do with PSOC, single chip solution.

View attachment 198745

IDE, PSOC Creator, and compiler free.

Debug board \$ 10 for this.

As you can see most resources, as shown in right hand window, unused, available for other
functions.

Code maybe max 15 lines of code. Waveform out can be standard, sine, square, pulse, tri, saw, or any
arbitrary user waveform.

Regards, Dana.
Generating a waveform is the simple part. Amplifying it and converting it to sound is the hard part. You can buy a set of speakers that go down to 25 Hz if you have enough money, the challenge is that lower 1 to 20 Hz range. And the amplifiers that go down to DC are rare and expensive.

Joined Jan 15, 2015
6,548
Back in my 'partying' days, I bought a cassette tape that had separate sounds for each side of the headphones you had to listen to it with. It didn't work with the speakers. Smoke some illegal herbal substance and listen to the tape and WOW. Talk about trippy.
Been there and done that. Then before tape with vinyl there was the classic play Black Sabbath at 78 speed.

Ron

BobTPH

Joined Jun 5, 2013
4,779
And the amplifiers that go down to DC are rare and expensive.
Easily built with an op amp and push pull output stage. I could make one with parts on hand.

Bob