[SOLVED] RF Emission from Piezoelectric Buzzer

Audioguru said:

I wish you didn't remind me that my remaining days, hours, minutes and seconds of my life are running out since I am 70 years old. I hope I live well for another 20 years.

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I moved to live in the countryside where it is so boring one year feels like twenty.

Audioguru said:

I wish you didn't remind me that my remaining days, hours, minutes and seconds of my life are running out since I am 70 years old. I hope I live well for another 20 years.

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I hope I make it to 70.

Earlier in life conversation centred around work, then around family, now around ailments. We begin to know exactly what is likely to be the cause of our death.

With that knowledge, we can continue in the same old fashion, or use each second. Personally I find the concept of "micromorts" very helpful, especially comparing the micromorts associated with different activities with the micromorts of simply being alive.

Personally I like to help those who really appreciate it, and do for myself, those things I can and want to do on my bucket list, the rest , like Obama said to the whitehouse correspondents just say .. bucket.

SunnySkyguy said:

Personally I like to help those who really appreciate it, ...

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I get a great deal of satisfaction from helping those who will benefit from my help - there's a subtle distinction.

Trying to give help to those that will not benefit reduces the amount of help I can give to those who may benefit. My time is resource-constrained and therefore a zero-sum resource.

I think your contribution is valuable to everyone who understands and may benefit now or in future. The loss is only your time spent vs time saved of many, so I count it as positive sum if you enjoy what you share.

SunnySkyguy said:

Personally I like to help those who really appreciate it, and do for myself, those things I can and want to do on my bucket list, the rest , like Obama said to the whitehouse correspondents just say .. bucket.

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I have an answer to this one but no much point saying it because I'll just get the 'bucket'.

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tggzzz said:

I get a great deal of satisfaction from helping those who will benefit from my help - there's a subtle distinction.

Trying to give help to those that will not benefit reduces the amount of help I can give to those who may benefit. My time is resource-constrained and therefore a zero-sum resource.

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Most men when reach their 60's feel the urge to pass on their experience and wisdom. The truth is that what we have to give is mostly useless to the next generation. Beside why shouldn't they suffer from their mistakes like we did, bucket.

The best lessons are those we learn ourselves but the wisest learn from others.

Hello

Could these act as a receiving antenna for RF?

No, they are crimp connectors, I used 1000's of them when I was with Telecom
they wont act as antennas, but any wire can act as an antenna

you are still being very paranoid

davenn said:

but any wire can act as an antenna

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So you're saying they can be used as an antenna?

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I researched the Great Seal Bug and I suspect my bug operates on the same principle. I think the carrier wave is generated by the ringer IC.

Oddly enough the length of the positive and negative leads of the piezo transducer is the same length as the Great Seal Bug antenna - 9 inches.

What Dave is telling you is ANY conductive surface can be an antenna. That means mains wiring, the room lighting wiring, the filament in the light bulb, the spoon you stir you coffee with, the chair you are sitting on, handles on the desk drawer, the clip on your pen, jewelery, wristwatches as well as telephone related things. Just stabbing in the dark at anything you don't recognize will get you nowhere.

Paranoia about antennas is just plain silly, an antenna alone cannot radiate a signal, it needs a driving force, a "carrier generator" and a "modulator", the thing to add the audio to the signal. In order to carry information, mathematically, the RF has to be no less than twice the frequency of the information it has to carry so the two tone oscillator in the ringer IC would only be able to carry audio tones up to about 400Hz, if everyone in the office has very loud, very deep voices and hold their conversations only while the phone is ringing, it might work. But consider this: apart from being extremely muffled (human voice range is mostly between 300Hz and 4KHz), it would be like listening to a feather drop with your head in the back end of a jet engine and the antenna wires for say 800Hz ringer tone would be 375Km long!

If you are still convinced the phone is being tapped, wrap aluminum foil around it. Ringer sound will still get out relatively unhindered and you can leave a gap around the hookswitch and keypad so you can still make calls.

EricaS, you will never be safe until you use hammer and smash that ringer. Remains throw in a distant trashcan. Buy another of different brand and use it until you get convinced someone is spying on you. Then repeat the procedure.

Borber said:

EricaS, you will never be safe until you use hammer and smash that ringer. Remains throw in a distant trashcan. Buy another of different brand and use it until you get convinced someone is spying on you. Then repeat the procedure.

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That wont be sufficient, EricaS has to do the same to the handle of the drawer, the bulb filament and so on...

betwixt said:

In order to carry information, mathematically, the RF has to be no less than twice the frequency of the information it has to carry so the two tone oscillator in the ringer IC would only be able to carry audio tones up to about 400Hz, if everyone in the office has very loud, very deep voices and hold their conversations only while the phone is ringing, it might work.

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Is it feasible that the ringer IC was swopped with another IC then relabeled to look like the original?

As discussed verbosely before, the ringer IC is only powered while the high ring AC voltage is present on the line. Besides slipping a manipulated ringer IC, the offender must also provide a permanent power supply for the IC which could be detected.

I found something unusual.
I'm using an Icom IC-R20 communications receiver.
The receiver is set to 151 kHz AM.

Near the telephone I get a faint signal that is only static.
As I move away from the phone the signal fades, the closer I get to the phone the stronger it becomes.

The RF is surely coming from the phone but this is not clear room audio.

Incidently I switched my air conditioner off while listening to the static. When I switch the air conditioner on and off there is interruption in the static sound for the break moment when I switch on and off only.

I haven't found this on any other frequency.

Does this mean anything?

EricaS said:

The receiver is set to 151 kHz AM.

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Possibly a switch mode power supply.
https://www.onsemi.com/pub_link/Collateral/LM2596-D.PDF

A pulse and square edge current pulse by definition contain infinite frequencies in reality limited by rise time and EMI filters.

The death of a star implodes and creates very high EMI continuous spectrum of frequencies detected by satellites as high as gamma rays.

This is normal EMI from switching regulators or motor surge current on start.

eg lightning is limited in rise time to ~1us so it can be detected hundreds of km away on AM radio but less on VHF ham and not at all on FM.

Are you saying the EMI from the phone is creating that?

Yes thats what I said but low enough to pass FCC or Cispre or CE requirements for EMI unless it is a non-compliant chinese or indian phone.