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'[EE] sending a clock over DC power lines'
2007\03\09@170818 by alan smith

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Somewhere in the back of my mind.....I recall reading/hearing/seeing about sending data over DC power lines.  One example was for ham rotor controls, to eliminate the multiconductor cables, it just sent a serial data stream over the DC power.
 
 So, this application is to send a 65mS clock over the DC power lines (24VDC).  Anyone done this before, or have a link to a circuit?


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2007\03\09@171704 by peter green

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>   So, this application is to send a 65mS clock over the DC power
> lines (24VDC).  Anyone done this before, or have a link to a circuit?
not done it before but i belive the basic principle would be to modulate it onto a carrier and then couple that carrier to the line.

much easier if you control the other stuff on the line than if you don't.


2007\03\09@180038 by stef mientki

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peter green wrote:
>>   So, this application is to send a 65mS clock over the DC power
>> lines (24VDC).  Anyone done this before, or have a link to a circuit?
>>    
> not done it before but i belive the basic principle would be to modulate it onto a carrier and then couple that carrier to the line.
>
> much easier if you control the other stuff on the line than if you don't.
>
>
>  
I did it once to control about 20 trains on 1 rail system.
The trick I used was very simple, but worked great:
put a few diodes in series with the power supply
and put an mosfet across those diodes, now you modulate te DC power.
Maybe you also take a look at Power over Ethernet.

--
cheers,
Stef Mientki
http://pic.flappie.nl

2007\03\09@182519 by peter green

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sounds rather lossy.

the way i'd do it is put an inductor in series with the power and load (remember for noise sensitive loads to put a paralell cap after the inductor)

then couple your signals and and out of the line with capacitors.



2007\03\09@182837 by Jinx

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>  So, this application is to send a 65mS clock over the DC power
> lines (24VDC).  Anyone done this before, or have a link to a circuit?

Alan, this works well between two PICs. The original circuit was
from a Plessey handbook describing a 100 ohm twisted pair link
between an MV500 IR encoder/transmitter and MV601 receiver/
decoder. I used this at the time for wired 5-bit commands to motor
controllers, as well as wireless IR

Basically the Vcc for each chip is held stable by the electrolytics
and the bit in between carries the data. The receiving pin can be
a comparator or ADC input, or add another transistor to boost
the pulse to logic level. Components and practicality will depend
on what current is passing through the wire to supply the transmitter.
For short clicks though, the transmitter's reservoir cap should cope



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2007\03\09@210445 by Herbert Graf

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On Fri, 2007-03-09 at 14:08 -0800, alan smith wrote:
> Somewhere in the back of my mind.....I recall reading/hearing/seeing about sending data over DC power lines.  One example was for ham rotor controls, to eliminate the multiconductor cables, it just sent a serial data stream over the DC power.
>    
>   So, this application is to send a 65mS clock over the DC power lines (24VDC).  Anyone done this before, or have a link to a circuit?

Haven't done it, but have a look at DCC control used in model
railroading (i.e. http://www.dccwiki.com/Main_Page), might give you some
ideas. TTYL

2007\03\10@024139 by Vasile Surducan

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On 3/9/07, stef mientki <s.mientkispamKILLspammailbox.kun.nl> wrote:
> peter green wrote:
> >>   So, this application is to send a 65mS clock over the DC power
> >> lines (24VDC).  Anyone done this before, or have a link to a circuit?
> >>
> > not done it before but i belive the basic principle would be to modulate it onto a carrier and then couple that carrier to the line.
> >
> > much easier if you control the other stuff on the line than if you don't.
> >
> >
> >
> I did it once to control about 20 trains on 1 rail system.
> The trick I used was very simple, but worked great:
> put a few diodes in series with the power supply
> and put an mosfet across those diodes, now you modulate te DC power.
> Maybe you also take a look at Power over Ethernet.

Another way will be to supply the DC from a constant current generator
(high output impedance) and modulate either the current at the input
of the current generator or modulating directly in the line using a
series capacitor.
Depends how clean must be the 24V line at the load side, that should
be the starting point.

2007\03\10@073437 by Rich

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It could be sent over an AC or a DC line.  Many intercoms send voice over
the AC lines.  The thing you might want think about is capacitive coupling
your pulse to the line on transmit and also receive end.

{Original Message removed}

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