# Bi-di sine

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#### Helix

##### New Member

Hi everyone!

I stumbled across one problem. I need the waveform displayed on the image for haptics purposes. I can generate it digitally, but this has limits by means of my sound card. If there is a way of generating the same waveform at 1MHz it would be a huge playground for me. input is one sine. I guess a shift register, logic gate and op amplifiers are needed, but I can't figure out how.
Any ideas?

#### rjenkinsgb

##### Well-Known Member
I'd use a zero crossing detector, eg. a suitable comparator, feeding the clock of a bistable such as a D type flip flop, so that alternates once each full cycle of the input, synchronised with the zero crossing.

Then use the output of that to control analog switches or an analog multiplexer, selecting either the input signal or an inverted version of the input.

That should give the alternating two positive + two negative peak waveform.

#### unclejed613

##### Well-Known Member
use an analog multiplier like an MC1496 feeding the X input with a sine wave, and the Y input with a square wave of half the frequency of the sine wave.

#### gophert

##### Well-Known Member
use an analog multiplier like an MC1496 feeding the X input with a sine wave, and the Y input with a square wave of half the frequency of the sine wave.
And don't try to generate the half frequency, just use a flip flop triggered by the rising edge of the sine wave.

#### kubeek

##### Well-Known Member
I´d ask you what is the purpose of such wave? I doubt any haptic repsonse from your fingers will react to anything at 1MHz or even above. Does the signal ned to look like that, or will some trapezoid approximation be enough?

#### ronsimpson

##### Well-Known Member
Here is a "Y6600 Digital 12-60MHz Dual Channel DDS Function Arbitrary Waveform Signal Generator Frequency Meter - 60MHz" that can make that wave form at 1mhz for $90.00usd. BangGood.com You can draw a wave form of any kind you want up to 8000 points. There is a 30, 50 & 60mhz versions. Here is a second option:$54.00 "DANIU FY3224S (FY3200S-24M) 24MHz Dual-channel Arbitrary Waveform DDS Function Signal Generator Sine Square Wave Sweep Counter "

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#### unclejed613

##### Well-Known Member
And don't try to generate the half frequency, just use a flip flop triggered by the rising edge of the sine wave.
you read my mind.... one other thing is that the square wave must be bipolar, not a logic level. logic level would only turn the sine wave on and off, you need to use a bipolar square wave to have it invert then not invert.

#### Helix

##### New Member
That was fast.
I have a Feeltech signal generator. There is an arbitrary waveform option. I have to learn how to get this wave.
MC1496 modulator is out of option. Only input signal is a sine wave. Flip-flop might just work.
For kubeek: First answer would be: hollow sounds move me on the dancefloor. Second one: I intend to test particles response to this signal. I can't wait to see how water surface or sand on the plate takes form to this signal. Just a big curiosity.
You know, everything nowadays is done with square wave signals disregarding matters natural response to harmonics. Did you know that matter and atmosphere are processing harmonics as the wave propagates through it. Some harmonics are more favourable than the others, leaving hollow sounding signal and suppressing anything fat and sharp. Don't think of an explosion, think of a continuous sound such as trains horn. It takes a good ear and strong sound from a far to spot it. Sound of Jupiter is a good example albeit vacuum of space haven't got much tangible matter. Very wide diapazone of hollowness. It sounds like a grinding blade. There's kind of a fractal-like property to it as you stretch out this wave.
Or am I just hallucinating.

#### AnalogKid

##### Well-Known Member
I need the waveform displayed on the image for haptics purposes.
generating the same waveform at 1MHz
i MHz haptics? Don't think so. Mass is essentially a low pass filter, and there is no way a rock (no matter how small) or a drop of water will respond to anything that fast, or even 10% of that fast. 1 MHz is the center of the AM broadcast band. If sand could respond to that, the dirt around broadcast towers would be jumping, and moisture in the soil would burst into steam.

The AM radio transmitter owned by OSU is in the middle of the golf OSU course. The sand traps don't move.

What are "hollow sounds"?

ak

#### Helix

##### New Member
I didn't think of 1MHz as operating frequency for haptic purposes, but rather as of absolute maximum.
Hollow sound sounds hollow like a didgeridoo or a square wave through low pass filter.

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