Voice powered radios

[YT2095]

I do not think it has to be much more efficient than talking in front of a loudspeaker and measuring its output as a microphone.

 

actualy you probably wouldn`t get anything usable employing that method (too many losses), I was thinking that the pick-up device would be closely coupled with the mouth like a small gas/dust mask, trapping much more energy of airflow.

you still wouldn`t get a whole heck of alot of power, but it would be a usable

[DV8 2XL]

Correction: The David Clark voice powered telephone sets produce 20 microamps at 60 millivolts on average on a 600 ohm loop. This is actually quite a bit of power if you think in terms of fully integrated CMOS radios ('radio on a chip') type systems.

[YT2095]

Correction: The David Clark voice powered telephone sets produce 20 microamps at 60 millivolts on average on a 600 ohm loop. This is actually quite a bit of power if you think in terms of fully integrated CMOS radios ('radio on a chip') type systems.

Hmmm... according to my calculations that`s a Total RF output of 1.2uW Max discounting any losses.

not exactly the BBC is it

[DV8 2XL]

Or the CBC

 

I was just pointing out that there is a bit more energy available than we have been assuming to this point. The telephones after all are working into a 600 ohm impedance which is almost the equivalent of a dead short by CMOS standards.

 

Anyway I'm not looking to work skip with these things; 15-20 metres of range would be more than enough for my application.

[DV8 2XL]

'年代のＣＱ誌に、ラジオ放送の電波を受信、検波して電源とする製作例がのっていましたが、それとは違います。しかし送信機というからには何らかのエネルギー源が無い事には送信できようはずはありません。種明かしをすると、マイクに向かってしゃべる音声エネルギーを電源に送信するのです。もちろん音声エネルギーの一部は同時に変調にも使用されるので、振幅変調された高周波信号を発生できます。回路図をご覧ください。いろいろなマイクをためしてみましたが、いわゆるスピーカー、それも結構大方のものの方が音声を効率よく電気エネルギーに変換できる事がわかりました、但し、スピーカーのインピーダンスは８Ω'

 

"This is AM transmitter, using no power supply. It moves only by the voice power. Audio power is translated for electric power and it excite radio frequency oscillator. And by the way, audio power modulates the radio frequency signal. 8cm speaker is used for the microphone."

 

http://www.intio.or.jp/jf10zl/PLTX.htm

[YT2095]

ah yes! as I suspected

 

the 1`st part is a power Multiplier (diodes caps), the second part uses an N channel FET (also predicted). the step-up transformer is a novelty though, Good idea

[DV8 2XL]

Ok, I finally got the story. This OLD tech, dropped in the 80's.

Here is what I was told by a Health and Safety officer who answered an email I sent several days ago:

 

- They were used for Class 4 entries, which is a full suit with self-contained air working in a deadly and or explosive atmosphere situation.

 

- The comm units were integrated into the head gear

 

-They worked on a low frequency; around 200khz at the center.

 

-The link was asymmetric: a relatively powerful transmitter and sensitive receiver on the 'outside' end, passive receiver and transmitter on the inside.

 

-You had to shout your lungs out to drive the passive transmitter.

 

Apparently they were replaced by low power active comms running on watch batteries, and also entry protocols, and the design of these spaces has changed to the point where solo class 4 entries are rare events.

 

So I guess that's it