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little circuit problem

On a sunny day (Sat, 11 May 2019 07:27:22 -0700) it happened John Larkin wrote in :

This was my idea with DTMF, the 1MHz is FM

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Note the ebay link I gave for the encoder, that chip has serial in data and clock. Do not know if you have a processor at the receiver side. Those same chips also come with 4 bit parallel in (no idea bout the price) as drawn here.

I am not saying 'do it that way', but that system can do audio too.

If you have an ethernet link, and both systems run Linux, then if you install 'festival' speech synthesizer on the Rx side, this will listen for TCP audio messages on port 1234 (as example); while [ 1 ] ; do netcat -l -p 1234 | festival --tts ; sleep 1 ;done

and then all the Tx side has to do (replace 1270.0.1 with IP of receiver): echo "hello I am number one, all is OK here" | netcat -c 127.0.0.1 1234

Works worldwide... Understood by everybody ;-)

netcat is cool!

The 'sleep' statement is so you can simply abort the thing with ctrl C...

Reply to
Jan Panteltje
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Good. So few people who post to SED are interested in or skilled at electronic design. Or seem to ever do it.

Little circuit puzzles are fun.

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin

Why?

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin

Otherwise tr is passing uncontrolled current peaks c to e from the 0.1uF.

NT

Reply to
tabbypurr

High current yes but "uncontrolled" is debatable. There is intrinsic silicon resistance; capacitor esr; track resistance; limited base drive; hfe depression at high Ic; extreme short duration; etc etc which often means further resistance unnecessary. But by all means add a few ohms when you build this circuit :)

piglet

Reply to
Piglet

0.1 uF charged to a few volts is a microjoule at best. That's not going to fry any transistor.

The pumped 1n cap limits base current anyhow.

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin

one LED per Rx.

no tone = I'm not there= light off

continuous tone = I'm here = light on

tone pulseing 1 / second = I'm here and Rx data, = light flashing.

m
Reply to
makolber

This is slick, a minimal way to make two frequencies:

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The lowest pair is 17 and 34 MHz, which we can probably handle at the receiver.

Maxim and Silabs make silicon oscillators too.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

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