little circuit problem

[John Larkin]

Assume I have a transmitter box T. It drives four remote receiver
boxes R1 R2 R3 R4. There are four bidirectional AC-coupled (telecom
style) duplex fiberoptic links.

We only need to transmit from four ports on T to Rn, so the return
links are wasted. So we figured we could return a status indication
from each R box that could drive a couple of LEDs at each tx port of
the T box.

We'd send back three states from each R: I'm dead, I'm here, and I'm
here and receiving your signal. The tx ports would each have two LEDs,
called LINK and DATA or something. Cute little light pipe things.

So, how about some maximally simple circuits at each end to convey
those three states, available as two TTL levels at R, back to the LEDs
on the T box? The tosa/rosa things are all 3.3V differential CML logic
levels.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[DJ Delorie]

Maybe this is naive, but why not just put a red-green LED across the
rosa signals? That way you have red (off), green (on), and yellow
(toggling) options. You could AC-couple one of the directions to get
off/green/yellow or maybe off/green/red.

The next simplest circuit... is a pair of tiny PICs talking serial over
that link. Two chips

 

[John Larkin]

On Thu, 09 May 2019 12:51:40 -0400, DJ Delorie <dj@delorie.com> wrote:

Maybe this is naive, but why not just put a red-green LED across the
rosa signals? That way you have red (off), green (on), and yellow
(toggling) options. You could AC-couple one of the directions to get
off/green/yellow or maybe off/green/red.

The CML rosa sigs are too weak to drive LEDs directly, and are AC
coupled. These telecom links seem to not work well below about 1 MHz.

The next simplest circuit... is a pair of tiny PICs talking serial over
that link. Two chips

I don't think the ac-coupled links would send async ascii-type
signals. They could send square waves of various frequencies, or
dc-balanced NRZ or biphase or 8B10B data.

Someone here has suggested using a small FPGA in, at least, the T box.
But that needs design and per-unit programming somehow. The upside is
that we could probably feed the rosa CML outputs directly into some
FPGA differential input.



--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[DJ Delorie]

John Larkin <jjlarkin@highland_snip_technology.com> writes:

The CML rosa sigs are too weak to drive LEDs directly, and are AC
coupled. These telecom links seem to not work well below about 1 MHz.

Hmmm... could they be made compatible with a CANbus tranceiver? That
still implies MCU, plus the two CAN chips, but it's another option...

(or some other off-the-shelf tranceiver, like LVD-to-ttl)

 

[Chris Jones]

On 10/05/2019 03:47, John Larkin wrote:

On Thu, 09 May 2019 12:51:40 -0400, DJ Delorie <dj@delorie.com> wrote:


Maybe this is naive, but why not just put a red-green LED across the
rosa signals? That way you have red (off), green (on), and yellow
(toggling) options. You could AC-couple one of the directions to get
off/green/yellow or maybe off/green/red.

The CML rosa sigs are too weak to drive LEDs directly, and are AC
coupled. These telecom links seem to not work well below about 1 MHz.


The next simplest circuit... is a pair of tiny PICs talking serial over
that link. Two chips

I don't think the ac-coupled links would send async ascii-type
signals. They could send square waves of various frequencies, or
dc-balanced NRZ or biphase or 8B10B data.

Someone here has suggested using a small FPGA in, at least, the T box.
But that needs design and per-unit programming somehow. The upside is
that we could probably feed the rosa CML outputs directly into some
FPGA differential input.

or a serdes? You could wire up some of the parallel inputs of the serdes
so that it always makes AC.

 

[John Larkin]

On Fri, 10 May 2019 13:45:35 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:

On 10/05/2019 03:47, John Larkin wrote:
On Thu, 09 May 2019 12:51:40 -0400, DJ Delorie <dj@delorie.com> wrote:


Maybe this is naive, but why not just put a red-green LED across the
rosa signals? That way you have red (off), green (on), and yellow
(toggling) options. You could AC-couple one of the directions to get
off/green/yellow or maybe off/green/red.

The CML rosa sigs are too weak to drive LEDs directly, and are AC
coupled. These telecom links seem to not work well below about 1 MHz.


The next simplest circuit... is a pair of tiny PICs talking serial over
that link. Two chips

I don't think the ac-coupled links would send async ascii-type
signals. They could send square waves of various frequencies, or
dc-balanced NRZ or biphase or 8B10B data.

Someone here has suggested using a small FPGA in, at least, the T box.
But that needs design and per-unit programming somehow. The upside is
that we could probably feed the rosa CML outputs directly into some
FPGA differential input.


or a serdes? You could wire up some of the parallel inputs of the serdes
so that it always makes AC.

I'm thinking that an R box could send a square wave back to T. 1 MHz
means "I'm here" and 4 MHz means "I'm getting your data." That's some
simple oscillator with one TTL input from the signal detector. (The
other bit of the 3-state code is just Vcc.)

The T box now needs a discriminator for each return channel, driving
two LEDs.

It's a not-too-critical but cute problem to come up with minimal
circuits to do this.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Jan Panteltje]

4046 freq too low PC output high, freq too high PC output low sort of thing, 2 LEDs on that pin.
No signal at all maybe both light (would have to try that)?
You can use it to make the frequencies too.


PS
come to Sink of it:
one 4046 as FM mod at say 1 Mhz on the Tx side,
the other as FM demod PLL on the Rx side.
Now you can send any digital serial data you want,
or you can use a EPROM at the Tx side with a 4040 counter and R2R network to say:
'I am number one and things are OK here', etc,
'I am number two and am overheated'
and an audio amp on the Rx side with a small or BIG speaker.

Its easy, have done that, FM link with 4046.
PIC would work too, but programming,....

 

[Jan Panteltje]

On a sunny day (Thu, 09 May 2019 21:23:23 -0700) it happened John Larkin
<jjlarkin@highlandtechnology.com> wrote in
<nku9de9bqmgq6qbu0i76v1kum951o3af6k@4ax.com>:

I'm thinking that an R box could send a square wave back to T. 1 MHz
means "I'm here" and 4 MHz means "I'm getting your data." That's some
simple oscillator with one TTL input from the signal detector. (The
other bit of the 3-state code is just Vcc.)

The T box now needs a discriminator for each return channel, driving
two LEDs.

It's a not-too-critical but cute problem to come up with minimal
circuits to do this.

4046 freq too low PC output high, freq too high PC output low sort of thing, 2 LEDs on that pin.
No signal at all maybe both light (would have to try that)?
You can use it to make the frequencies too.

 

[John Larkin]

On Fri, 10 May 2019 08:34:51 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

4046 freq too low PC output high, freq too high PC output low sort of thing, 2 LEDs on that pin.
No signal at all maybe both light (would have to try that)?
You can use it to make the frequencies too.


PS
come to Sink of it:
one 4046 as FM mod at say 1 Mhz on the Tx side,
the other as FM demod PLL on the Rx side.
Now you can send any digital serial data you want,
or you can use a EPROM at the Tx side with a 4040 counter and R2R network to say:
'I am number one and things are OK here', etc,
'I am number two and am overheated'
and an audio amp on the Rx side with a small or BIG speaker.

Its easy, have done that, FM link with 4046.
PIC would work too, but programming,....

I'd forgotten all about the 4046... haven't used one in decades. The
transmit end (in an R box) could just use the VCO part. The HC4046 can
do up to 24 MHz at 3.3 volts.

As the receiver in the T box, the pll dc output could drive two
comparitors to light my two LEDs.

I was also considering a tachometer circuit, an HC123 one-shot and a
lowpass RC, to convert frequency to DC voltage, into that same dual
comparator. HC123 is a dual, so that's a slight simplification.

The receiver still needs a converter from the rosa's CML diff output
to TTL. I guess that can't be avoided.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[John Larkin]

On Fri, 10 May 2019 08:34:51 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

4046 freq too low PC output high, freq too high PC output low sort of thing, 2 LEDs on that pin.
No signal at all maybe both light (would have to try that)?
You can use it to make the frequencies too.


PS
come to Sink of it:
one 4046 as FM mod at say 1 Mhz on the Tx side,
the other as FM demod PLL on the Rx side.
Now you can send any digital serial data you want,
or you can use a EPROM at the Tx side with a 4040 counter and R2R network to say:
'I am number one and things are OK here', etc,
'I am number two and am overheated'
and an audio amp on the Rx side with a small or BIG speaker.

Its easy, have done that, FM link with 4046.
PIC would work too, but programming,....

In homage (apply French accent) to your graphic style, I submit as the
receiver and LED driver

https://www.dropbox.com/s/ty52a6xlj9e9taj/1M4M_Det.JPG?dl=0

which accepts the wimpy CML directly. If the transmitter is a 4046
VCO, the two frequencies can be whatever works best.

Oh, add a resistor to ground on the lower comparator input.

Adding two schottky diodes, comparator inputs to ground, would be
interesting. That allows cheap slow comparators to be used.

Too tricky maybe. I'm thinking HC4046 at the send end and the HC123
tachometer thing at the receiver. Just do the CML to TTL.







--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Piglet]

On 09/05/2019 16:40, John Larkin wrote:

Assume I have a transmitter box T. It drives four remote receiver
boxes R1 R2 R3 R4. There are four bidirectional AC-coupled (telecom
style) duplex fiberoptic links.

We only need to transmit from four ports on T to Rn, so the return
links are wasted. So we figured we could return a status indication
from each R box that could drive a couple of LEDs at each tx port of
the T box.

We'd send back three states from each R: I'm dead, I'm here, and I'm
here and receiving your signal. The tx ports would each have two LEDs,
called LINK and DATA or something. Cute little light pipe things.

So, how about some maximally simple circuits at each end to convey
those three states, available as two TTL levels at R, back to the LEDs
on the T box? The tosa/rosa things are all 3.3V differential CML logic
levels.

You could simplify two leds down to one. Off = no connection; solid-on =
connected; Flickering-on = connected and data traffic.

piglet

 

[Jan Panteltje]

On a sunny day (Fri, 10 May 2019 08:26:59 -0700) it happened John Larkin
<jjlarkin@highlandtechnology.com> wrote in
<am4bdehgep68lef14pfoqohea5ackkhsqu@4ax.com>:

On Fri, 10 May 2019 08:34:51 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

4046 freq too low PC output high, freq too high PC output low sort of thing, 2 LEDs on that pin.
No signal at all maybe both light (would have to try that)?
You can use it to make the frequencies too.


PS
come to Sink of it:
one 4046 as FM mod at say 1 Mhz on the Tx side,
the other as FM demod PLL on the Rx side.
Now you can send any digital serial data you want,
or you can use a EPROM at the Tx side with a 4040 counter and R2R network to say:
'I am number one and things are OK here', etc,
'I am number two and am overheated'
and an audio amp on the Rx side with a small or BIG speaker.

Its easy, have done that, FM link with 4046.
PIC would work too, but programming,....


In homage (apply French accent) to your graphic style, I submit as the
receiver and LED driver

https://www.dropbox.com/s/ty52a6xlj9e9taj/1M4M_Det.JPG?dl=0

which accepts the wimpy CML directly. If the transmitter is a 4046
VCO, the two frequencies can be whatever works best.

Oh, add a resistor to ground on the lower comparator input.

Adding two schottky diodes, comparator inputs to ground, would be
interesting. That allows cheap slow comparators to be used.

Too tricky maybe. I'm thinking HC4046 at the send end and the HC123
tachometer thing at the receiver. Just do the CML to TTL.

Yes, had to look at your 'graphics' for a while,
you use Q of LC to get high voltage on C to bottom comparator for 4 MHz.
But you may have a logic problem, would need 2 tuned circuits, one for each frequency?


Yes 74HC123 could work, has only 5 pF input capacitance.
Maybe sensitive to noise, false triggering.


4046 PLL and comparators on the control voltage should also work.

Will think about it

DTMF encoder - and decoder chips come to mind too, could be cheap,
but those use audio range frequencies, gives you more bits though.
Could use FM and the 4046 PLL to send and demodulate those frequencies.

I am sure there are many other possibilities

 

[John Larkin]

On Fri, 10 May 2019 16:56:44 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Fri, 10 May 2019 08:26:59 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
am4bdehgep68lef14pfoqohea5ackkhsqu@4ax.com>:

On Fri, 10 May 2019 08:34:51 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

4046 freq too low PC output high, freq too high PC output low sort of thing, 2 LEDs on that pin.
No signal at all maybe both light (would have to try that)?
You can use it to make the frequencies too.


PS
come to Sink of it:
one 4046 as FM mod at say 1 Mhz on the Tx side,
the other as FM demod PLL on the Rx side.
Now you can send any digital serial data you want,
or you can use a EPROM at the Tx side with a 4040 counter and R2R network to say:
'I am number one and things are OK here', etc,
'I am number two and am overheated'
and an audio amp on the Rx side with a small or BIG speaker.

Its easy, have done that, FM link with 4046.
PIC would work too, but programming,....


In homage (apply French accent) to your graphic style, I submit as the
receiver and LED driver

https://www.dropbox.com/s/ty52a6xlj9e9taj/1M4M_Det.JPG?dl=0

which accepts the wimpy CML directly. If the transmitter is a 4046
VCO, the two frequencies can be whatever works best.

Oh, add a resistor to ground on the lower comparator input.

Adding two schottky diodes, comparator inputs to ground, would be
interesting. That allows cheap slow comparators to be used.

Too tricky maybe. I'm thinking HC4046 at the send end and the HC123
tachometer thing at the receiver. Just do the CML to TTL.

Yes, had to look at your 'graphics' for a while,
you use Q of LC to get high voltage on C to bottom comparator for 4 MHz.
But you may have a logic problem, would need 2 tuned circuits, one for each frequency?

The LED states are: both off, one on, and both on. The LINK led should
light if any frequency is coming back from an R box. The DATA led
should light only on 4 MHz.



--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Jan Panteltje]

On a sunny day (Fri, 10 May 2019 11:37:07 -0700) it happened John Larkin
<jjlarkin@highland_snip_technology.com> wrote in
<o1hbdedokleuanb87bcvu95tr113g55ntr@4ax.com>:

On Fri, 10 May 2019 16:56:44 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:
Yes, had to look at your 'graphics' for a while,
you use Q of LC to get high voltage on C to bottom comparator for 4 MHz.
But you may have a logic problem, would need 2 tuned circuits, one for each frequency?

The LED states are: both off, one on, and both on. The LINK led should
light if any frequency is coming back from an R box. The DATA led
should light only on 4 MHz.

Ok, got it.

I just checked ebay for DTMF encoder and decoder chips,
the generators are about 29 cent:
https://www.ebay.com/itm/361785015081

The receivers about 47 cent:
https://www.ebay.com/itm/371082820810

Saves a lot of tinkering and is an universal system... 4 bits out.
Press 1, 2, 4, 8 (MOSFET in Tx side as key switch) for 4 LEDs?

 

[John Larkin]

On Fri, 10 May 2019 19:13:50 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Fri, 10 May 2019 11:37:07 -0700) it happened John Larkin
jjlarkin@highland_snip_technology.com> wrote in
o1hbdedokleuanb87bcvu95tr113g55ntr@4ax.com>:

On Fri, 10 May 2019 16:56:44 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:
Yes, had to look at your 'graphics' for a while,
you use Q of LC to get high voltage on C to bottom comparator for 4 MHz.
But you may have a logic problem, would need 2 tuned circuits, one for each frequency?

The LED states are: both off, one on, and both on. The LINK led should
light if any frequency is coming back from an R box. The DATA led
should light only on 4 MHz.

Ok, got it.

I just checked ebay for DTMF encoder and decoder chips,
the generators are about 29 cent:
https://www.ebay.com/itm/361785015081

The receivers about 47 cent:
https://www.ebay.com/itm/371082820810

Saves a lot of tinkering and is an universal system... 4 bits out.
Press 1, 2, 4, 8 (MOSFET in Tx side as key switch) for 4 LEDs?

The fiber links are AC coupled and some are useless below 1 MHz, so I
need to go fast.

HC4046 is 22 cents. Good suggestion.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[John Larkin]

On Fri, 10 May 2019 11:37:07 -0700, John Larkin
<jjlarkin@highland_snip_technology.com> wrote:

On Fri, 10 May 2019 16:56:44 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Fri, 10 May 2019 08:26:59 -0700) it happened John Larkin
jjlarkin@highlandtechnology.com> wrote in
am4bdehgep68lef14pfoqohea5ackkhsqu@4ax.com>:

On Fri, 10 May 2019 08:34:51 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

4046 freq too low PC output high, freq too high PC output low sort of thing, 2 LEDs on that pin.
No signal at all maybe both light (would have to try that)?
You can use it to make the frequencies too.


PS
come to Sink of it:
one 4046 as FM mod at say 1 Mhz on the Tx side,
the other as FM demod PLL on the Rx side.
Now you can send any digital serial data you want,
or you can use a EPROM at the Tx side with a 4040 counter and R2R network to say:
'I am number one and things are OK here', etc,
'I am number two and am overheated'
and an audio amp on the Rx side with a small or BIG speaker.

Its easy, have done that, FM link with 4046.
PIC would work too, but programming,....


In homage (apply French accent) to your graphic style, I submit as the
receiver and LED driver

https://www.dropbox.com/s/ty52a6xlj9e9taj/1M4M_Det.JPG?dl=0

which accepts the wimpy CML directly. If the transmitter is a 4046
VCO, the two frequencies can be whatever works best.

Oh, add a resistor to ground on the lower comparator input.

Adding two schottky diodes, comparator inputs to ground, would be
interesting. That allows cheap slow comparators to be used.

Too tricky maybe. I'm thinking HC4046 at the send end and the HC123
tachometer thing at the receiver. Just do the CML to TTL.

Yes, had to look at your 'graphics' for a while,
you use Q of LC to get high voltage on C to bottom comparator for 4 MHz.
But you may have a logic problem, would need 2 tuned circuits, one for each frequency?

The LED states are: both off, one on, and both on. The LINK led should
light if any frequency is coming back from an R box. The DATA led
should light only on 4 MHz.

Here's a CML (or ECL) to TTL converter for about 7 cents. That can
drive my HC123 tachometer, which can drive a dual comparator to light
the LEDs at 1MHz and 4MHz. 45 cents total maybe.

https://www.dropbox.com/s/el5dh5pm6g0r2a7/CML_to_TTL_1.jpg?dl=0

The FSK tx end is your 4046, another 40 cents maybe.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Piglet]

On 10/05/2019 17:31, Piglet wrote:

On 09/05/2019 16:40, John Larkin wrote:


Assume I have a transmitter box T. It drives four remote receiver
boxes R1 R2 R3 R4. There are four bidirectional AC-coupled (telecom
style) duplex fiberoptic links.

We only need to transmit from four ports on T to Rn, so the return
links are wasted. So we figured we could return a status indication
from each R box that could drive a couple of LEDs at each tx port of
the T box.

We'd send back three states from each R: I'm dead, I'm here, and I'm
here and receiving your signal. The tx ports would each have two LEDs,
called LINK and DATA or something. Cute little light pipe things.

So, how about some maximally simple circuits at each end to convey
those three states, available as two TTL levels at R, back to the LEDs
on the T box? The tosa/rosa things are all 3.3V differential CML logic
levels.



You could simplify two leds down to one. Off = no connection; solid-on =
connected; Flickering-on = connected and data traffic.

piglet

In the spirit of gray on gray sketches here is mine:

<https://www.dropbox.com/s/v18svcy5kre4ymi/ActivityBlink.jpg?dl=0>

The Mhz oscillator is gated off at a few Hz if there is a stream of data
pulses. Everything is AC coupled so a stuck high/ stuck low fault is
apparent.

The 50ms blink-on blink-off half shots could probably be tidied up into
a 74HC123

piglet

 

[Piglet]

On 11/05/2019 15:27, John Larkin wrote:

On Sat, 11 May 2019 09:26:51 +0100, Piglet <erichpwagner@hotmail.com
wrote:

On 10/05/2019 17:31, Piglet wrote:
On 09/05/2019 16:40, John Larkin wrote:


Assume I have a transmitter box T. It drives four remote receiver
boxes R1 R2 R3 R4. There are four bidirectional AC-coupled (telecom
style) duplex fiberoptic links.

We only need to transmit from four ports on T to Rn, so the return
links are wasted. So we figured we could return a status indication
from each R box that could drive a couple of LEDs at each tx port of
the T box.

We'd send back three states from each R: I'm dead, I'm here, and I'm
here and receiving your signal. The tx ports would each have two LEDs,
called LINK and DATA or something. Cute little light pipe things.

So, how about some maximally simple circuits at each end to convey
those three states, available as two TTL levels at R, back to the LEDs
on the T box? The tosa/rosa things are all 3.3V differential CML logic
levels.



You could simplify two leds down to one. Off = no connection; solid-on =
connected; Flickering-on = connected and data traffic.

piglet


In the spirit of gray on gray sketches here is mine:

https://www.dropbox.com/s/v18svcy5kre4ymi/ActivityBlink.jpg?dl=0

The Mhz oscillator is gated off at a few Hz if there is a stream of data
pulses. Everything is AC coupled so a stuck high/ stuck low fault is
apparent.

The 50ms blink-on blink-off half shots could probably be tidied up into
a 74HC123

piglet


Interesting. But the light pipes come in twos, and we'd have to
explain the single-LED blink patterns to the users. The two LEDs can
be LINK and DATA which is arguably clear in meaning. Maybe.

The data seen at the recever is GHz stuff, so that needs a separate
detector that supplies a TTL level to this link. That will already
drive a local DATA led on the R box.

No problem. I saw the network activity light on my modem/router which
indicates the same kind of thing: disconnect, connect, active.

You asked for simple and I enjoyed the challenge.

piglet

 

[John Larkin]

On Sat, 11 May 2019 09:26:51 +0100, Piglet <erichpwagner@hotmail.com>
wrote:

On 10/05/2019 17:31, Piglet wrote:
On 09/05/2019 16:40, John Larkin wrote:


Assume I have a transmitter box T. It drives four remote receiver
boxes R1 R2 R3 R4. There are four bidirectional AC-coupled (telecom
style) duplex fiberoptic links.

We only need to transmit from four ports on T to Rn, so the return
links are wasted. So we figured we could return a status indication
from each R box that could drive a couple of LEDs at each tx port of
the T box.

We'd send back three states from each R: I'm dead, I'm here, and I'm
here and receiving your signal. The tx ports would each have two LEDs,
called LINK and DATA or something. Cute little light pipe things.

So, how about some maximally simple circuits at each end to convey
those three states, available as two TTL levels at R, back to the LEDs
on the T box? The tosa/rosa things are all 3.3V differential CML logic
levels.



You could simplify two leds down to one. Off = no connection; solid-on =
connected; Flickering-on = connected and data traffic.

piglet


In the spirit of gray on gray sketches here is mine:

https://www.dropbox.com/s/v18svcy5kre4ymi/ActivityBlink.jpg?dl=0

The Mhz oscillator is gated off at a few Hz if there is a stream of data
pulses. Everything is AC coupled so a stuck high/ stuck low fault is
apparent.

The 50ms blink-on blink-off half shots could probably be tidied up into
a 74HC123

piglet

Interesting. But the light pipes come in twos, and we'd have to
explain the single-LED blink patterns to the users. The two LEDs can
be LINK and DATA which is arguably clear in meaning. Maybe.

The data seen at the recever is GHz stuff, so that needs a separate
detector that supplies a TTL level to this link. That will already
drive a local DATA led on the R box.




--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Jan Panteltje]

On a sunny day (Sat, 11 May 2019 07:27:22 -0700) it happened John Larkin
<jjlarkin@highlandtechnology.com> wrote in
<lkmdde1f8ch1gcavkv6nnj81lhed1di905@4ax.com>:

The data seen at the recever is GHz stuff, so that needs a separate
detector that supplies a TTL level to this link. That will already
drive a local DATA led on the R box.

This was my idea with DTMF, the 1MHz is FM
http://panteltje.com/pub/DTMF_1MHz_link_IMG_6915.JPG

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...