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Help Grandma Hear Her Doorbell!

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Salome2:
Please give me your ideas on how you experts would solve this problem.
  I am getting stuck on how to recognize the doorbell waveform to ring an extended doorchime.

(Should I post this as a new post?
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Granny is nearing 87 and  nearly deaf as a loaf of bread.

Her helper persons arrive at her apt building but often cannot get in because Granny can't hear the existing doorbell or even her Smartphone. She can't sleep with  her hearing aid on and often struggles to get them properly on her ears!

Her doorbell works 100%, it is  part of an intercom in the corridor of her apt, about 30-feet from her bedroom door, 70-ft to the kitchen. I would not like to try to mount the new doorbell ringer switch outside at the doorbell panel or tamper with in anyway the existing intercom/doorbell.

So I bought a much louder wireless door chime that works well, Granny says she can hear it well when it is placed next to her bed or even in the kitchen. It's even loud enough there for her to hear with the radio on.
Now, all I need to do is detect the old doorbell ring to ring the new extended distance door chime.

To do this, I need to build a circuit use as little power as possible to continuously monitor and detect a doorbell ring by using a small electrolet mic that will be glued to the doorbell/intercom near the front door of her apt.

I recorded the existing doorbell chime on my IPhone and played the sound back to the electrolet mic and got a good scope picture of the doorbell chime waveform.

I chose a PIC16F18456 chip to detect the doorbell sound signature because I have it on hand. This chip can run its 12-bit A2D peripheral while in sleep mode and the ADC has threshold detection to trigger an interrupt to awaken the MCU up at a set threshold value.

The idea here is to use the least amount of battery power possible, so that it would take many months to a year or so to replace/recharge the battery powering my design.

The electrolet mic uses only 133uA and the A2D by itself only uses 160uA running in MCU sleep mode.
I can use, for instance any small footprint battery, but I do have a 23A 9-V Lithium Roundcell 300mAH and also a 3.7V 2200mAH flat SmartPhone battery also on hand.

What I see viewing the chime waveform at the mic output:

Doorbell tones are bursts of a cone-shaped waveform showing a distinct chain of a 2-mSec period waveform, its highest amplitude peaks every 2-mSec (even with an async 4-th harmonic mixed in) to make a chime sound. Its just a continuous distorted 2-mSec sinewave.

The ring waveform chime is a continuous stream of a repeating 2-mSec waveform that slowly decays in amplitude until the 1/2 amplitude point is reached in about 1.8-Secs followed by a 300mS pause.

Two doorbell tones each button-press. Holding down the front door button keeps repeating the doorbell signal.

What can I write in embedded C code to accurately detect only the original ringtone without false triggering or missing any doorbell ring? With the lowest power used?

shabaz:
Hi,

Personally I would not even bother with a microcontroller.
I'd consider (say) a BJT amplifier for the electret mic, followed by an integrator (could even be as simple as a diode rectifier and a capacitor with resistor across it), or use a low-power dual op-amp for it all perhaps. And a CMOS Schmitt trigger gate.

The above would be aimed at just detecting any loud noise that lasts long enough for the Schmitt trigger to fire. If the mic is placed very close to the existing chime speaker (could experiment with a tube or something around the mic), then that should be the loudest sound picked up anyway.

AVI-crak:
An anecdote from childhood:
Petyka asks Vasily Ivanovich for money for experiments. Three days later, Vasily Ivanovich finds him drunk in the barn, a notebook with notes lying next to him:
“Experience one: take a cockroach, tear off two legs, whistle, the cockroach runs away.
Experience two: take a cockroach, tear off four legs, whistle, the cockroach runs away.
Experience three: tear off all the legs of the cockroach, whistle, the cockroach in place.
Conclusion: a cockroach without legs cannot hear.

SiliconWizard:

--- Quote from: AVI-crak on September 11, 2024, 07:33:57 pm ---An anecdote from childhood:
Petyka asks Vasily Ivanovich for money for experiments. Three days later, Vasily Ivanovich finds him drunk in the barn, a notebook with notes lying next to him:
“Experience one: take a cockroach, tear off two legs, whistle, the cockroach runs away.
Experience two: take a cockroach, tear off four legs, whistle, the cockroach runs away.
Experience three: tear off all the legs of the cockroach, whistle, the cockroach in place.
Conclusion: a cockroach without legs cannot hear.

--- End quote ---

Sounds like half of current scientific publication. :-DD

Salome2:
Tovarishch AVI-crak, Is cockroach Ukraine?   

Shabas..is your circuit for detecting cockroach also?

Your approach is maybe a possible solution, and my comment is not to offend you, but to add some humor.

Your circuit probably has many uses and it lacks power usage calculation and circuit detail, and the devil is in the details. I think a MCU-based solution is viable and can be precisely tuned to detect the first bell ring. From what I guess, the simpler no-MCU approach would require tuning.

I would have to hire a cockroach to go down and keep pressing the bell button to best test and tune your idea to work without fail.     

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