He wants a butterfly valve installed in ear canal. He wants it to remain wide open til a certain db level is reached........the valve will close and remain so....til db level decreases.

 

Please find the attached document.
Thanks

 

He wants a butterfly valve installed in ear canal. He wants it to remain wide open til a certain db level is reached........the valve will close and remain so....til db level decreases.

Yes actually

 

@jagruti mahajan , Do you have any specifications that you need to meet, or do you just have to demonstrate some basic functionality.

I also noticed that you posted a hand-written list on another thread. I tried to read it but could not make out what you are trying to do there. Could you please explain it here?

I want to design product with those functionalities.

 

From the first description, what is asked for is an amplifier with very little distortion (Easy) that with a slight increase in input goes into hard limiting and saturation so that nothing gets through (Very difficult) The big problem is having the transition from linear to saturated happen with just a slight level rise, and happen instantly. The simple way, instead, to achieve that is to have an analog to digital converter hearing the input sound, and a logic circuit that constantly looks at the magnitude of that sound. The instant that the magnitude exceeds the limit value the connection is cut off, or possibly just an attenuator is switched in line.. But that would not offer much in the line of an AGC function. All it takes is a digital comparison circuit to monitor the A/D binary output. Not a trivial package, but entirely possible.

 

From the first description, what is asked for is an amplifier with very little distortion (Easy) that with a slight increase in input goes into hard limiting and saturation so that nothing gets through (Very difficult) The big problem is having the transition from linear to saturated happen with just a slight level rise, and happen instantly. The simple way, instead, to achieve that is to have an analog to digital converter hearing the input sound, and a logic circuit that constantly looks at the magnitude of that sound. The instant that the magnitude exceeds the limit value the connection is cut off, or possibly just an attenuator is switched in line.. But that would not offer much in the line of an AGC function. All it takes is a digital comparison circuit to monitor the A/D binary output. Not a trivial package, but entirely possible.

Thanks for your response.
But all I want to do is with analog electronics. No DSP

 

Have you investigated diode clippers?



This may be the easiest way to your basic functionality.

 

Hello,

The circuit Dick showed you is for hard clipping.
On post #29 I posted already a PDF with information on AGC circuit design.

Bertus

 

Thanks for your response.
But all I want to do is with analog electronics. No DSP

Using an analog to digital converter, and a binary comparator, is not DSP by any stretch. You could also do the same with a comparator and adjustable reference, BUT it would be a bit challenging to have it work fast enough. The problem is that the comparator wants to see a voltage corresponding to an average level, while you want to trigger on an instant value. Probably something close to a "Peak Limiter" used for recording would be a useful starting point. But since I have no clue about your technical background I don't know where to be more descriptive.

 

Diodes sorta look like butterflies. They open and close pretty fast. A little study might even make them adjustable.

Is personal protection the primary concern?......or is the audio quantity(cleanliness) of the switching, important?

A hearing canal amp with an adjustable clipper circuit might suffice.

 

I have played that game. Back in post #6 I mention what I use today and while they never would have been suited for my military days they work real well for things like gunshots. Time in service followed by time on flight decks over the years, combined with just plain old age took a toll on my hearing. These things work really well in that they can amplify normal sounds around me like conversation and totally clip gun fire on the range. I would think this ability could be built into any of the available hearing aids on the current market. On the firing range it is so nice not to hear the loud gunfire but yet be able to carry on a conversation. During conversation the loud sounds like gunfire are just clipped. You hear the shots but quietized.

Ron

They used to say, that with gun shots muffs where much better than in ear stuff. Said that a lot of the sound of a close shot was transferred from the bones of the checks to inner ear. Don't know if they still say that or not, don't shoot much anymore.

 

I agree with the ear "muff" approach. Don't care for insertion. The muffs give one more room for circuitry/battery too. And room for future communications.

I would also look into a mechanical device. Perhaps a multi film opening/closing diaphragm device on muff, that closes/collapses upon a certain db pressure.

Edit: one could also share your protection device without sharing earwax.

 

They used to say, that with gun shots muffs where much better than in ear stuff. Said that a lot of the sound of a close shot was transferred from the bones of the checks to inner ear. Don't know if they still say that or not, don't shoot much anymore.

They still get picked up by skull, facial bones, and cartilage and are conducted to the cochlea where they are detected. Very little of this energy, a negligible amount I was told, passes through the hammer, anvil, and stirrup -the three little bones that act as an impedance match for transferring energy from the eardrum to the cochlea. I was told that most of noise-associated hearing loss is due to damage to these three bones.

Edit:
Attached visually enhanced copy of jagruti mahajan's document. It looks like a sort of block diagram of her device. The file is large to preserve the details of the penmanship.

Edit #2: Special thanks to KJ6EAD for proofreading this post.

 

Using an analog to digital converter, and a binary comparator, is not DSP by any stretch. You could also do the same with a comparator and adjustable reference, BUT it would be a bit challenging to have it work fast enough. The problem is that the comparator wants to see a voltage corresponding to an average level, while you want to trigger on an instant value. Probably something close to a "Peak Limiter" used for recording would be a useful starting point. But since I have no clue about your technical background I don't know where to be more descriptive.

I will check what you suggested.
I completed my masters in electrical control systems. But feeling like lacking in basics now.

 

Have you investigated diode clippers?

View attachment 159477

This may be the easiest way to your basic functionality.

Yes I will go through it.
Thank you.

 

Diodes sorta look like butterflies. They open and close pretty fast. A little study might even make them adjustable.

Is personal protection the primary concern?......or is the audio quantity(cleanliness) of the switching, important?

A hearing canal amp with an adjustable clipper circuit might suffice.

I think both are important at the same time.

 

There is a problem with diode clippers that ham radio operators discovered many years ago. Diode clipping produces harmonics in large quantities at many multiples of the original frequency. And that is just for a sign wave. so while it can, at least in theory, clamp an amplitude, in reality it makes a lot of noise. Thus the development of DSP. MUCH more complex, but able to avoid that problem.
Not trying to discourage, just hoping to save you some effort. Seeing what others have done is a great way to determine what paths have not been taken. It may also serve to provide new insights into your process.