Slow-Mo Wired Transmission

[Douglas Beeson]

Hi all,

I want to set up a very simple communication system to allow two devices to propagate a digital signal (3.3 or 5V) across a wire that may be 10 meters long at the most. The speed is very low, only about 20 Hz max. The devices will be battery powered, so I want low power, but there is a little hitch: each of the two devices will be processing an amplified audio signal, single-ended, and tied to the local battery ground. I am concerned about tying the two device grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Thanks!

doug
--
Douglas Beeson <c.difficile@gmail.com>

 

[whit3rd]

On Tuesday, September 9, 2014 10:09:45 AM UTC-4, Doug Beeson wrote:

I want to set up a very simple communication system to allow two devices to propagate a digital signal (3.3 or 5V) across a wire that may be 10 meters long at the most. The speed is very low, only about 20 Hz max. The devices will be battery powered, so I want low power, but there is a little hitch: each of the two devices will be processing an amplified audio signal, single-ended, and tied to the local battery ground. I am concerned about tying the two device grounds together and getting noise into the audio.



Do I need isolation here? Any suggestions?

If your power is from batteries, and you have a ground wire between the devices, you HAVE
isolation. Don't make lots of extra ground connections!

A useful amplifier for low power might be the old LM13700; you can program the
power on this opamp-like device, down to a couple of microamps. Two per package,
with Darlington followers (if needed for power switching).

 

[tim]

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two devices
to propagate a digital signal (3.3 or 5V) across a wire that may be 10
meters long at the most. The speed is very low, only about 20 Hz max.
The devices will be battery powered, so I want low power, but there is a
little hitch: each of the two devices will be processing an amplified
audio signal, single-ended, and tied to the local battery ground. I am
concerned about tying the two device grounds together and getting noise
into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one for
each direction?

Isolation is probably a good idea, to keep the grounds separate if for no
other reason.

--
www.wescottdesign.com

 

[John Larkin]

On Tue, 9 Sep 2014 10:09:45 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

Hi all,

I want to set up a very simple communication system to allow two devices to propagate a digital signal (3.3 or 5V) across a wire that may be 10 meters long at the most. The speed is very low, only about 20 Hz max. The devices will be battery powered, so I want low power, but there is a little hitch: each of the two devices will be processing an amplified audio signal, single-ended, and tied to the local battery ground. I am concerned about tying the two device grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Thanks!

doug

Are the "local battery grounds" connected to any earth grounds of any
sort? If not, you won't have a ground noise problem.

20 Hz audio?


--

John Larkin Highland Technology, Inc

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

 

[Douglas Beeson]

On Tue, 09 Sep 2014 10:02:37 -0500
tim <tim@seemywebsite.com> wrote:

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two devices
to propagate a digital signal (3.3 or 5V) across a wire that may be 10
meters long at the most. The speed is very low, only about 20 Hz max.
The devices will be battery powered, so I want low power, but there is a
little hitch: each of the two devices will be processing an amplified
audio signal, single-ended, and tied to the local battery ground. I am
concerned about tying the two device grounds together and getting noise
into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one for
each direction?

Single wire with a ground return. I could also provide a power line to drive a digital isolator on the other end, if need be.

Isolation is probably a good idea, to keep the grounds separate if for no
other reason.

--
www.wescottdesign.com

--
Douglas Beeson <c.difficile@gmail.com>

 

[Douglas Beeson]

On Tue, 09 Sep 2014 08:13:02 -0700
John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 9 Sep 2014 10:09:45 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

Hi all,

I want to set up a very simple communication system to allow two devices to propagate a digital signal (3.3 or 5V) across a wire that may be 10 meters long at the most. The speed is very low, only about 20 Hz max. The devices will be battery powered, so I want low power, but there is a little hitch: each of the two devices will be processing an amplified audio signal, single-ended, and tied to the local battery ground. I am concerned about tying the two device grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Thanks!

doug

Are the "local battery grounds" connected to any earth grounds of any
sort? If not, you won't have a ground noise problem.

The audio going through each device will potentially come from different amplifiers. I guess I'm afraid of a difference in "common mode" voltages across those two amps. If I tie them together with a ground wire, isn't there a risk of noise?

20 Hz audio?

Very boring songs ;-). No seriously, it's not the audio signal itself that's 20 Hz, just the signal that drives a gate to enable/disable the audio.

--

John Larkin Highland Technology, Inc

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

--
Douglas Beeson <c.difficile@gmail.com>

 

[Douglas Beeson]

On Tue, 9 Sep 2014 08:25:34 -0700 (PDT)
whit3rd <whit3rd@gmail.com> wrote:

On Tuesday, September 9, 2014 10:09:45 AM UTC-4, Doug Beeson wrote:

I want to set up a very simple communication system to allow two devices to propagate a digital signal (3.3 or 5V) across a wire that may be 10 meters long at the most. The speed is very low, only about 20 Hz max. The devices will be battery powered, so I want low power, but there is a little hitch: each of the two devices will be processing an amplified audio signal, single-ended, and tied to the local battery ground. I am concerned about tying the two device grounds together and getting noise into the audio.



Do I need isolation here? Any suggestions?

If your power is from batteries, and you have a ground wire between the devices, you HAVE
isolation. Don't make lots of extra ground connections!

A useful amplifier for low power might be the old LM13700; you can program the
power on this opamp-like device, down to a couple of microamps. Two per package,
with Darlington followers (if needed for power switching).

Thanks for the suggestion. I'll take a look!


--
Douglas Beeson <c.difficile@gmail.com>

 

[John Larkin]

On Tue, 9 Sep 2014 11:44:36 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

On Tue, 09 Sep 2014 08:13:02 -0700
John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 9 Sep 2014 10:09:45 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

Hi all,

I want to set up a very simple communication system to allow two devices to propagate a digital signal (3.3 or 5V) across a wire that may be 10 meters long at the most. The speed is very low, only about 20 Hz max. The devices will be battery powered, so I want low power, but there is a little hitch: each of the two devices will be processing an amplified audio signal, single-ended, and tied to the local battery ground. I am concerned about tying the two device grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Thanks!

doug

Are the "local battery grounds" connected to any earth grounds of any
sort? If not, you won't have a ground noise problem.

The audio going through each device will potentially come from different amplifiers. I guess I'm afraid of a difference in "common mode" voltages across those two amps. If I tie them together with a ground wire, isn't there a risk of noise?

That didn't answer the question: do the different battery-powered
boxes each have local earth ground paths?

Even if they do, a ground wire will reduce noise.

20 Hz audio?

Very boring songs ;-). No seriously, it's not the audio signal itself that's 20 Hz, just the signal that drives a gate to enable/disable the audio.

For max paranoia, use RS422 differential. Or optocouplers.


--

John Larkin Highland Technology, Inc

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

 

[Douglas Beeson]

On Tue, 09 Sep 2014 10:08:26 -0700
John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 9 Sep 2014 11:44:36 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On Tue, 09 Sep 2014 08:13:02 -0700
John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 9 Sep 2014 10:09:45 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

Hi all,

I want to set up a very simple communication system to allow two devices to propagate a digital signal (3.3 or 5V) across a wire that may be 10 meters long at the most. The speed is very low, only about 20 Hz max. The devices will be battery powered, so I want low power, but there is a little hitch: each of the two devices will be processing an amplified audio signal, single-ended, and tied to the local battery ground. I am concerned about tying the two device grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Thanks!

doug

Are the "local battery grounds" connected to any earth grounds of any
sort? If not, you won't have a ground noise problem.

The audio going through each device will potentially come from different amplifiers. I guess I'm afraid of a difference in "common mode" voltages across those two amps. If I tie them together with a ground wire, isn't there a risk of noise?

That didn't answer the question: do the different battery-powered
boxes each have local earth ground paths?

Even if they do, a ground wire will reduce noise.

No local earth ground path from the boxes. The audio is single-ended and the amplifiers are powered by 12VDC power supplies whose DC side is presumably floating.

So my question really comes down to whether there is a risk of current flowing from one box to another along a local (not earth) ground wire if the boxes are connected to different amplifiers.

20 Hz audio?

Very boring songs ;-). No seriously, it's not the audio signal itself that's 20 Hz, just the signal that drives a gate to enable/disable the audio.

For max paranoia, use RS422 differential. Or optocouplers.

I was thinking optocouplers or digital isolators. By may be overkill, you are right.

--

John Larkin Highland Technology, Inc

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

--
Douglas Beeson <c.difficile@gmail.com>

 

[John Larkin]

On Tue, 9 Sep 2014 13:53:02 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

On Tue, 09 Sep 2014 10:08:26 -0700
John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 9 Sep 2014 11:44:36 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On Tue, 09 Sep 2014 08:13:02 -0700
John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 9 Sep 2014 10:09:45 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

Hi all,

I want to set up a very simple communication system to allow two devices to propagate a digital signal (3.3 or 5V) across a wire that may be 10 meters long at the most. The speed is very low, only about 20 Hz max. The devices will be battery powered, so I want low power, but there is a little hitch: each of the two devices will be processing an amplified audio signal, single-ended, and tied to the local battery ground. I am concerned about tying the two device grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Thanks!

doug

Are the "local battery grounds" connected to any earth grounds of any
sort? If not, you won't have a ground noise problem.

The audio going through each device will potentially come from different amplifiers. I guess I'm afraid of a difference in "common mode" voltages across those two amps. If I tie them together with a ground wire, isn't there a risk of noise?

That didn't answer the question: do the different battery-powered
boxes each have local earth ground paths?

Even if they do, a ground wire will reduce noise.

No local earth ground path from the boxes. The audio is single-ended and the amplifiers are powered by 12VDC power supplies whose DC side is presumably floating.

So my question really comes down to whether there is a risk of current flowing from one box to another along a local (not earth) ground wire if the boxes are connected to different amplifiers.

It won't work *without* a ground return wire.


--

John Larkin Highland Technology, Inc

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

 

[Tim Wescott]

On Tue, 09 Sep 2014 08:25:34 -0700, whit3rd wrote:

On Tuesday, September 9, 2014 10:09:45 AM UTC-4, Doug Beeson wrote:

I want to set up a very simple communication system to allow two
devices to propagate a digital signal (3.3 or 5V) across a wire that
may be 10 meters long at the most. The speed is very low, only about 20
Hz max. The devices will be battery powered, so I want low power, but
there is a little hitch: each of the two devices will be processing an
amplified audio signal, single-ended, and tied to the local battery
ground. I am concerned about tying the two device grounds together and
getting noise into the audio.



Do I need isolation here? Any suggestions?

If your power is from batteries, and you have a ground wire between the
devices, you HAVE isolation. Don't make lots of extra ground
connections!

The power is from batteries, but he's connecting the boxes to amplifiers
plugged into the wall, and presumably getting ground references from them.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[Tim Wescott]

On Tue, 09 Sep 2014 11:36:55 -0400, Douglas Beeson wrote:

On Tue, 09 Sep 2014 10:02:37 -0500 tim <tim@seemywebsite.com> wrote:

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two
devices to propagate a digital signal (3.3 or 5V) across a wire that
may be 10 meters long at the most. The speed is very low, only about
20 Hz max. The devices will be battery powered, so I want low power,
but there is a little hitch: each of the two devices will be
processing an amplified audio signal, single-ended, and tied to the
local battery ground. I am concerned about tying the two device
grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one
for each direction?

Single wire with a ground return. I could also provide a power line to
drive a digital isolator on the other end, if need be.

OK, you are VERY SLOWLY coughing up details, but you're not giving us a
big picture!!

* Yes, two conductors.

* Battery powered, but referenced to amplifiers that are plugged into the
wall

Well, that's a FEW details. I guess you don't really want your question
answered, but here: I'll make up a question for you and answer IT:

Since you'll only ever have two boxes, since one is a master and the
other is a slave, and since the communications is only ever one way, the
solution is simplicity itself: Put an opto-isolator in the slave, DO NOT
reference your master's return wire to your slave's ground, and just apply
a logic signal (capable of driving the opto) from the master.

There. Problem solved. If it doesn't happen to be _your_ problem, then
GIVE US ENOUGH DETAILS.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[Jim Thompson]

On Tue, 09 Sep 2014 16:24:16 -0500, Tim Wescott
<seemywebsite@myfooter.really> wrote:

On Tue, 09 Sep 2014 11:36:55 -0400, Douglas Beeson wrote:

On Tue, 09 Sep 2014 10:02:37 -0500 tim <tim@seemywebsite.com> wrote:

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two
devices to propagate a digital signal (3.3 or 5V) across a wire that
may be 10 meters long at the most. The speed is very low, only about
20 Hz max. The devices will be battery powered, so I want low power,
but there is a little hitch: each of the two devices will be
processing an amplified audio signal, single-ended, and tied to the
local battery ground. I am concerned about tying the two device
grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one
for each direction?

Single wire with a ground return. I could also provide a power line to
drive a digital isolator on the other end, if need be.

OK, you are VERY SLOWLY coughing up details, but you're not giving us a
big picture!!

* Yes, two conductors.

* Battery powered, but referenced to amplifiers that are plugged into the
wall

Well, that's a FEW details. I guess you don't really want your question
answered, but here: I'll make up a question for you and answer IT:

Since you'll only ever have two boxes, since one is a master and the
other is a slave, and since the communications is only ever one way, the
solution is simplicity itself: Put an opto-isolator in the slave, DO NOT
reference your master's return wire to your slave's ground, and just apply
a logic signal (capable of driving the opto) from the master.

There. Problem solved. If it doesn't happen to be _your_ problem, then
GIVE US ENOUGH DETAILS.

And here's an easy "opto" suitable for you application...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website.

It can even be made low-power... you only need to twang the
appropriate LED for as long as an edge transition, then back off to
zero.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Douglas Beeson]

On Tue, 09 Sep 2014 16:24:16 -0500
Tim Wescott <seemywebsite@myfooter.really> wrote:

On Tue, 09 Sep 2014 11:36:55 -0400, Douglas Beeson wrote:

On Tue, 09 Sep 2014 10:02:37 -0500 tim <tim@seemywebsite.com> wrote:

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two
devices to propagate a digital signal (3.3 or 5V) across a wire that
may be 10 meters long at the most. The speed is very low, only about
20 Hz max. The devices will be battery powered, so I want low power,
but there is a little hitch: each of the two devices will be
processing an amplified audio signal, single-ended, and tied to the
local battery ground. I am concerned about tying the two device
grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one
for each direction?

Single wire with a ground return. I could also provide a power line to
drive a digital isolator on the other end, if need be.

OK, you are VERY SLOWLY coughing up details, but you're not giving us a
big picture!!

* Yes, two conductors.

* Battery powered, but referenced to amplifiers that are plugged into the
wall

Well, that's a FEW details. I guess you don't really want your question
answered, but here: I'll make up a question for you and answer IT:

Since you'll only ever have two boxes, since one is a master and the
other is a slave, and since the communications is only ever one way, the
solution is simplicity itself: Put an opto-isolator in the slave, DO NOT
reference your master's return wire to your slave's ground, and just apply
a logic signal (capable of driving the opto) from the master.

Sorry about the lack of detail. I was trying to do this while attending a very boring meeting st work.

I want what you guessed: a master/slave relationship between the boxes where communication is uni-directional. I had imagined a solution as you suggest, with an opto-isolator on the slave, a signal wire and ground wire tied to the master (but not the slave). I had seen the ADUM 1246 part from Analog Solutions (http://www.analog.com/en/interface-isolation/digital-isolators/adum1246/products/product.html) and thought it looked promising as a one-component answer, as each box will need to be able to work as either master or slave (or both if daisy-chaining the boxes). In the case of the ADUM series parts I need to provide power on each side of the divide, so I can send 3.3 V over from the master. That would make

+++++ master VCC
_____ master signal
----- master grnd

three wires going to the slave.

There. Problem solved. If it doesn't happen to be _your_ problem, then
GIVE US ENOUGH DETAILS.

Thanks for your help, Tim. I think this is it.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

--
Douglas Beeson <c.difficile@gmail.com>

 

[Douglas Beeson]

On Tue, 09 Sep 2014 15:20:08 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 09 Sep 2014 16:24:16 -0500, Tim Wescott
seemywebsite@myfooter.really> wrote:

On Tue, 09 Sep 2014 11:36:55 -0400, Douglas Beeson wrote:

On Tue, 09 Sep 2014 10:02:37 -0500 tim <tim@seemywebsite.com> wrote:

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two
devices to propagate a digital signal (3.3 or 5V) across a wire that
may be 10 meters long at the most. The speed is very low, only about
20 Hz max. The devices will be battery powered, so I want low power,
but there is a little hitch: each of the two devices will be
processing an amplified audio signal, single-ended, and tied to the
local battery ground. I am concerned about tying the two device
grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one
for each direction?

Single wire with a ground return. I could also provide a power line to
drive a digital isolator on the other end, if need be.

OK, you are VERY SLOWLY coughing up details, but you're not giving us a
big picture!!

* Yes, two conductors.

* Battery powered, but referenced to amplifiers that are plugged into the
wall

Well, that's a FEW details. I guess you don't really want your question
answered, but here: I'll make up a question for you and answer IT:

Since you'll only ever have two boxes, since one is a master and the
other is a slave, and since the communications is only ever one way, the
solution is simplicity itself: Put an opto-isolator in the slave, DO NOT
reference your master's return wire to your slave's ground, and just apply
a logic signal (capable of driving the opto) from the master.

There. Problem solved. If it doesn't happen to be _your_ problem, then
GIVE US ENOUGH DETAILS.

And here's an easy "opto" suitable for you application...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website.

It can even be made low-power... you only need to twang the
appropriate LED for as long as an edge transition, then back off to
zero.

Thanks, Jim. I'll have a look.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

--
Douglas Beeson <c.difficile@gmail.com>

 

[Jim Thompson]

On Tue, 9 Sep 2014 21:41:42 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

On Tue, 09 Sep 2014 15:20:08 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 09 Sep 2014 16:24:16 -0500, Tim Wescott
seemywebsite@myfooter.really> wrote:

On Tue, 09 Sep 2014 11:36:55 -0400, Douglas Beeson wrote:

On Tue, 09 Sep 2014 10:02:37 -0500 tim <tim@seemywebsite.com> wrote:

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two
devices to propagate a digital signal (3.3 or 5V) across a wire that
may be 10 meters long at the most. The speed is very low, only about
20 Hz max. The devices will be battery powered, so I want low power,
but there is a little hitch: each of the two devices will be
processing an amplified audio signal, single-ended, and tied to the
local battery ground. I am concerned about tying the two device
grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one
for each direction?

Single wire with a ground return. I could also provide a power line to
drive a digital isolator on the other end, if need be.

OK, you are VERY SLOWLY coughing up details, but you're not giving us a
big picture!!

* Yes, two conductors.

* Battery powered, but referenced to amplifiers that are plugged into the
wall

Well, that's a FEW details. I guess you don't really want your question
answered, but here: I'll make up a question for you and answer IT:

Since you'll only ever have two boxes, since one is a master and the
other is a slave, and since the communications is only ever one way, the
solution is simplicity itself: Put an opto-isolator in the slave, DO NOT
reference your master's return wire to your slave's ground, and just apply
a logic signal (capable of driving the opto) from the master.

There. Problem solved. If it doesn't happen to be _your_ problem, then
GIVE US ENOUGH DETAILS.

And here's an easy "opto" suitable for you application...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website.

It can even be made low-power... you only need to twang the
appropriate LED for as long as an edge transition, then back off to
zero.


Thanks, Jim. I'll have a look.

...Jim Thompson

The posting...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website now includes the modified
"twanging" method.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Douglas Beeson]

On Wed, 10 Sep 2014 10:19:11 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 9 Sep 2014 21:41:42 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On Tue, 09 Sep 2014 15:20:08 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 09 Sep 2014 16:24:16 -0500, Tim Wescott
seemywebsite@myfooter.really> wrote:

On Tue, 09 Sep 2014 11:36:55 -0400, Douglas Beeson wrote:

On Tue, 09 Sep 2014 10:02:37 -0500 tim <tim@seemywebsite.com> wrote:

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two
devices to propagate a digital signal (3.3 or 5V) across a wire that
may be 10 meters long at the most. The speed is very low, only about
20 Hz max. The devices will be battery powered, so I want low power,
but there is a little hitch: each of the two devices will be
processing an amplified audio signal, single-ended, and tied to the
local battery ground. I am concerned about tying the two device
grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one
for each direction?

Single wire with a ground return. I could also provide a power line to
drive a digital isolator on the other end, if need be.

OK, you are VERY SLOWLY coughing up details, but you're not giving us a
big picture!!

* Yes, two conductors.

* Battery powered, but referenced to amplifiers that are plugged into the
wall

Well, that's a FEW details. I guess you don't really want your question
answered, but here: I'll make up a question for you and answer IT:

Since you'll only ever have two boxes, since one is a master and the
other is a slave, and since the communications is only ever one way, the
solution is simplicity itself: Put an opto-isolator in the slave, DO NOT
reference your master's return wire to your slave's ground, and just apply
a logic signal (capable of driving the opto) from the master.

There. Problem solved. If it doesn't happen to be _your_ problem, then
GIVE US ENOUGH DETAILS.

And here's an easy "opto" suitable for you application...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website.

It can even be made low-power... you only need to twang the
appropriate LED for as long as an edge transition, then back off to
zero.


Thanks, Jim. I'll have a look.

...Jim Thompson

The posting...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website now includes the modified
"twanging" method.

I don't see the twanging method on that file, but I do have another question:

It looks like the circuit provides a trickle of current (around 22 uA by my calculation) directly into the base of the 4AN25As. I was wondering why. Does this increase the switching speed?

Thanks,

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

--
Douglas Beeson <c.difficile@gmail.com>

 

[Jim Thompson]

On Thu, 11 Sep 2014 16:09:08 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

On Wed, 10 Sep 2014 10:19:11 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 9 Sep 2014 21:41:42 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On Tue, 09 Sep 2014 15:20:08 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 09 Sep 2014 16:24:16 -0500, Tim Wescott
seemywebsite@myfooter.really> wrote:

On Tue, 09 Sep 2014 11:36:55 -0400, Douglas Beeson wrote:

On Tue, 09 Sep 2014 10:02:37 -0500 tim <tim@seemywebsite.com> wrote:

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two
devices to propagate a digital signal (3.3 or 5V) across a wire that
may be 10 meters long at the most. The speed is very low, only about
20 Hz max. The devices will be battery powered, so I want low power,
but there is a little hitch: each of the two devices will be
processing an amplified audio signal, single-ended, and tied to the
local battery ground. I am concerned about tying the two device
grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one
for each direction?

Single wire with a ground return. I could also provide a power line to
drive a digital isolator on the other end, if need be.

OK, you are VERY SLOWLY coughing up details, but you're not giving us a
big picture!!

* Yes, two conductors.

* Battery powered, but referenced to amplifiers that are plugged into the
wall

Well, that's a FEW details. I guess you don't really want your question
answered, but here: I'll make up a question for you and answer IT:

Since you'll only ever have two boxes, since one is a master and the
other is a slave, and since the communications is only ever one way, the
solution is simplicity itself: Put an opto-isolator in the slave, DO NOT
reference your master's return wire to your slave's ground, and just apply
a logic signal (capable of driving the opto) from the master.

There. Problem solved. If it doesn't happen to be _your_ problem, then
GIVE US ENOUGH DETAILS.

And here's an easy "opto" suitable for you application...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website.

It can even be made low-power... you only need to twang the
appropriate LED for as long as an edge transition, then back off to
zero.


Thanks, Jim. I'll have a look.

...Jim Thompson

The posting...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website now includes the modified
"twanging" method.

I don't see the twanging method on that file, but I do have another question:

Pages 3-4... I reposted... refresh the page then try again.

It looks like the circuit provides a trickle of current (around 22 uA by my calculation) directly into the base of the 4AN25As. I was wondering why. Does this increase the switching speed?

Thanks,

[snip]

It's just a standard ol' cross-coupled NPN set/reset flop ;-)

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Douglas Beeson]

On Thu, 11 Sep 2014 16:42:57 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Thu, 11 Sep 2014 16:09:08 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On Wed, 10 Sep 2014 10:19:11 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 9 Sep 2014 21:41:42 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On Tue, 09 Sep 2014 15:20:08 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 09 Sep 2014 16:24:16 -0500, Tim Wescott
seemywebsite@myfooter.really> wrote:

On Tue, 09 Sep 2014 11:36:55 -0400, Douglas Beeson wrote:

On Tue, 09 Sep 2014 10:02:37 -0500 tim <tim@seemywebsite.com> wrote:

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two
devices to propagate a digital signal (3.3 or 5V) across a wire that
may be 10 meters long at the most. The speed is very low, only about
20 Hz max. The devices will be battery powered, so I want low power,
but there is a little hitch: each of the two devices will be
processing an amplified audio signal, single-ended, and tied to the
local battery ground. I am concerned about tying the two device
grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one
for each direction?

Single wire with a ground return. I could also provide a power line to
drive a digital isolator on the other end, if need be.

OK, you are VERY SLOWLY coughing up details, but you're not giving us a
big picture!!

* Yes, two conductors.

* Battery powered, but referenced to amplifiers that are plugged into the
wall

Well, that's a FEW details. I guess you don't really want your question
answered, but here: I'll make up a question for you and answer IT:

Since you'll only ever have two boxes, since one is a master and the
other is a slave, and since the communications is only ever one way, the
solution is simplicity itself: Put an opto-isolator in the slave, DO NOT
reference your master's return wire to your slave's ground, and just apply
a logic signal (capable of driving the opto) from the master.

There. Problem solved. If it doesn't happen to be _your_ problem, then
GIVE US ENOUGH DETAILS.

And here's an easy "opto" suitable for you application...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website.

It can even be made low-power... you only need to twang the
appropriate LED for as long as an edge transition, then back off to
zero.


Thanks, Jim. I'll have a look.

...Jim Thompson

The posting...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website now includes the modified
"twanging" method.

I don't see the twanging method on that file, but I do have another question:

Pages 3-4... I reposted... refresh the page then try again.

Ok, works now! It was my browser cache.

It looks like the circuit provides a trickle of current (around 22 uA by my calculation) directly into the base of the 4AN25As. I was wondering why. Does this increase the switching speed?

Thanks,

[snip]

It's just a standard ol' cross-coupled NPN set/reset flop ;-)

Right, ok, I see that now.

Thanks for your generous help as usual.

doug

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

--
Douglas Beeson <c.difficile@gmail.com>

 

[Jim Thompson]

On Thu, 11 Sep 2014 21:15:03 -0400, Douglas Beeson
<c.difficile@gmail.com> wrote:

On Thu, 11 Sep 2014 16:42:57 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Thu, 11 Sep 2014 16:09:08 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On Wed, 10 Sep 2014 10:19:11 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 9 Sep 2014 21:41:42 -0400, Douglas Beeson
c.difficile@gmail.com> wrote:

On Tue, 09 Sep 2014 15:20:08 -0700
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Tue, 09 Sep 2014 16:24:16 -0500, Tim Wescott
seemywebsite@myfooter.really> wrote:

On Tue, 09 Sep 2014 11:36:55 -0400, Douglas Beeson wrote:

On Tue, 09 Sep 2014 10:02:37 -0500 tim <tim@seemywebsite.com> wrote:

On Tue, 09 Sep 2014 10:09:45 -0400, Douglas Beeson wrote:

Hi all,

I want to set up a very simple communication system to allow two
devices to propagate a digital signal (3.3 or 5V) across a wire that
may be 10 meters long at the most. The speed is very low, only about
20 Hz max. The devices will be battery powered, so I want low power,
but there is a little hitch: each of the two devices will be
processing an amplified audio signal, single-ended, and tied to the
local battery ground. I am concerned about tying the two device
grounds together and getting noise into the audio.

Do I need isolation here? Any suggestions?

Do you mean one conductor, or a wire with a ground return? Do you wish
to multiplex all signals onto one "wire", or do you want to have one
for each direction?

Single wire with a ground return. I could also provide a power line to
drive a digital isolator on the other end, if need be.

OK, you are VERY SLOWLY coughing up details, but you're not giving us a
big picture!!

* Yes, two conductors.

* Battery powered, but referenced to amplifiers that are plugged into the
wall

Well, that's a FEW details. I guess you don't really want your question
answered, but here: I'll make up a question for you and answer IT:

Since you'll only ever have two boxes, since one is a master and the
other is a slave, and since the communications is only ever one way, the
solution is simplicity itself: Put an opto-isolator in the slave, DO NOT
reference your master's return wire to your slave's ground, and just apply
a logic signal (capable of driving the opto) from the master.

There. Problem solved. If it doesn't happen to be _your_ problem, then
GIVE US ENOUGH DETAILS.

And here's an easy "opto" suitable for you application...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website.

It can even be made low-power... you only need to twang the
appropriate LED for as long as an edge transition, then back off to
zero.


Thanks, Jim. I'll have a look.

...Jim Thompson

The posting...

PhotoCoupler-Fast.pdf

on the S.E.D/Schematics Page of my website now includes the modified
"twanging" method.

I don't see the twanging method on that file, but I do have another question:

Pages 3-4... I reposted... refresh the page then try again.


Ok, works now! It was my browser cache.


It looks like the circuit provides a trickle of current (around 22 uA by my calculation) directly into the base of the 4AN25As. I was wondering why. Does this increase the switching speed?

Thanks,

[snip]

It's just a standard ol' cross-coupled NPN set/reset flop ;-)

Right, ok, I see that now.

Thanks for your generous help as usual.

doug

[snip]

You are quite welcome! I hope this helps solve your issue!

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.