delabs Circuits

Showing posts with label Audio-Sound. Show all posts
Showing posts with label Audio-Sound. Show all posts

Friday, March 18, 2016

Hypersonic Speakers - Acoustic Heterodyning

i have been searching for any technical help regarding my project, hypersonic speakers,but my efforts were in vain. hypersonic speakers are interesting to work upon. kindly guide if if you have any knowledge regarding the topic. Mail from GA

This looks like something from the "Believe it or not", I cannot understand it well, but logging it here. - delabs

What Are Some Woody Norris Successes?

Hypersonic Speakers - Acoustic Heterodyning

Hypersonic Sound: Sound From Thin Air - Mix two signals in a nonlinear medium and you'll end up with four - two at the original frequencies....

"Acoustic heterodyning can be created by a single transducer or by a pair of transducers. A single transducer would be fed a signal at a "carrier frequency" and a second signal that would provide the desired (audible) difference frequencies when mixed with the carrier. If a pair of transducers were used, one would operate at the carrier frequency and the second at a frequency required to produce the desired output.

If the carrier frequency of the transducer were 200 kHz, an upward swing of 20 kHz - or just 10 percent - would cover the entire audio range. In theory, this should result in a response that is virtually flat across the audio range - something that no speaker"

Hypersonic Sound speakers are like Invisible headphones.

Sound technology turns the way you hear on its ear - Woody Norris, inventor of ultrasound technology,

Acoustical Society of America Lay Paper on Hypersonic Sound: -

HyperSonic Sound HSS from American Technology Corporation employs ultrasonics to create audible sound in the air. It works by using harmless ultrasonic tones that we can't hear

More from Woody Norris - HyperSonic Sound. speaker

"With conventional speakers, the sound is projected by moving the air containing the sound waves against a cone moving back and forth inside the box. But with Woody's speakers, it's a process that happens in the air itself. Sound is beamed at the wall and it comes off the wall where it is imbedded on top of the ultrasound. A process that happens in the air unimbeds it, or demodulates the two, so in essence, the room in which you are using the speakers is, itself, the speaker box. "

 Meet Woody Norris


Thanks for your reply for hypersonic speakers , but sir i am unable to have any positive feed backs as far as its making is concerned, i have contacted hypersonic industries also in this context, but they want me to buy a unit. i will see what i can do. thank you once again for your help.

Reply from GA

I dont know if this idea is good for college projects, but you can buy a Hypersonic Speaker and demonstrate an application in automation.


Tuesday, January 19, 2016

Speech Recorder and Sound Syntheizer

I needed some help with available ics to build a small sound recorder able to hold about 120 seconds of audio, preferebly voice. I managed to find one that uses an ISD25xx series ic, which is not available within this region.

mail from RT

Look at these pages......

Speech recognition using HM2007

"Isolated speech recognition systems can just handle words that are spoken separately. This is the most common speech recognition systems available today."

Speech Recorder and Sound Syntheizer

Paradoxical Sound Syntheizer

"The main property of paradoxical sounds is that their frequency do not change when you go an octave higher. This property is achieved thanks to an appropriate spectrum modelling."

A Digital Speech Synthesizer, the S3610 LPC-10

"Such sound-storing and playback chips are known as digital synthesizers, and they have been around since 1978, when Texas Instruments introduced the first single-chip speech synthesizer. TI's creation was first used in a company product called "Speak and Spell" - a toy that caused quite a stir and became very popular."


Tuesday, October 21, 2014

Graphic Equalizer Circuits

plz send me sound equalizer circuits. - email by AH
Search for ...... graphic equalizer circuits. You have many pages to see, and the navigation for all the pages is at bottom of every page. anyway, i did it for you,

Graphic Equalizer Circuits

10 Band Graphic Equalizer (sam)

"The circuit of graphic equalizer, allocates ten adjusting potesometer , that each one from them affects in a predetermined area of frequencies, the central frequency of which abstains a octave (double), from the central frequencies of her neighbouring regions."

3 Band graphic equalizer (andy)

This circuit is similar to ones that used to come in Philips audio books, so try this first. Now to design your own, learn the technique here ...

"Using a single op-amp this easy to make equalizer offers three ranges, low frequency,mid frequency,and high."

7 band Audio Graphic Equaliser

"The details shown are for a 7 band but the principle can be extended to almost any number of bands - if you can find accurate enough components."

Level, Tone and Balance Controls

Amplifiers, tone controls and other audio effect circuits at david's "Discover Circuits".


Friday, September 12, 2014

Noise and Hum in Audio Circuits

"I currently have a car stereo set that i use as an amplifier in my living room. but my main problem is that i a lot of noise hum when ever it is on especially when there happens to be a drop in the supply Voltage. i decided to use a voltage regulator and capacitor across (1600uF)...but it only reduced the hum a little. how can i completely eliminate the noise". - Question  by FP

Answer by delabs 

Ensure that the power supply has a full wave or bridge rectifier. If power supply transformer is say 12-0-12 two diodes must be there and a center tap ground OR If a square or round bridge is used with four leads or four diodes, then it is fine. Half wave rectification or a blown or leaky diode can cause this problem. Put all the filter caps you want and add a series choke as well the better the power supply the audio will be good.

Noise and Hum in Audio Circuits

The power supply transformer rating - voltage and current both may need to be boosted. Some very low budget transformers do not use CR-GO plates for lamination (i think it is Cold Rolled Grain Oriented ). They use plain thick metal plates without coating and hence hysteresis and eddy current both cause problems. Then you have ground loop hum and noise of semiconductors, the speaker ground and amplifier ground carry current and they should be directly connected to power supply ground, These you can understand by looking at these pages......

I am only aware of Phillips transistor based designs used 20 years back, but these have more...

Noise in Audio Amplifiers

"Noise has enormous nuisance value with sensitive (i.e. high gain) circuits, but the information provided by most IC and transistor makers.."

Avoiding Ground Loop Hum

"To solve the problem, the goal is to reduce the magnitude of the loop current. This is done simply by inserting isolation resistor(s) in series with the audio cable ground(s)..."

Audio, Power, and Control Lines

"The correct place for an audio ground is at the microphone connector entrance to the shield enclosure of the radio..."

Friday, May 23, 2014

Passive volume control

please if you don't mind I need to help to find a control circuit for volume of speaker 4 ohm or 8 ohm located in the another room far away of cassette or CD player by using only passive components with potentiometer without transformer.

mail from AD

i have attached to this mail a simple circuit you can build at home at low cost. This is the only alternative for the need that you have specified. it uses just a rotary switch and wire wound resistors.

Volume control circuit for speaker 4 ohm or 8 ohm located in the another room far away. by using only passive components. This gives limited control and helps reduce volume when a conversation starts. The resistors are very low value.

Passive volume control

Passive volume control with Potentiometer

A simple circuit you can build at home at low cost it uses just a rotary switch and wire wound resistors. Add more resistors and a rotary switch with more contacts for finer control.