rickman wrote:

Roger Hayter wrote on 11/18/2017 4:04 PM:
Stephen Thomas Cole wrote:



Gents, can you please **** off.

If you have nothing to contribute to the discussion why join in at all?

My personal theory as to why few commercial morse keys use reed switches
or optical switches is that that users like to able to connect their
morse keys to a wide range of voltages and impedances, especially if you
include traditional valve equipment. Both technologies are intolerant
of excessive voltages or current compared with a pair of solid metal
contacts. I don't think either speed, latency or debouncing are
significant factors or, at least, they could be designed out.

Not trying to be argumentative, but I'd like to understand the basis of your
point. Why would the three things above not be factors in using mechanical
switches in keys? Bouncing switch contacts do pose an issue for clean
keying of a transmitter, no? So the bouncing has to be smoothed out. That
means adding electronics which means interface specific again, no? I
supposed you could use a high voltage capacitor and no buffer. That would
be a simple RC with the R in series with the key to the controlled point.

But the debouncing is likely to be in the keyed equipment rather than
the key.

By the way, i meant jitter[1], latency and that debouncing was no more
significant than for mechanical switches. So I expressed myself rather
inaccurately.





Maybe I'm not grasping what you are saying. How do you see a simple
mechanical switch being used to control many types of equipment?

BTW, there are transistors available that will switch high voltages and
currents. So a simple interface circuit would serve for use with many types
of equipment and any type of key switch you wish to use.

[1] Not speed which is about the same as latency, but jitter due to the
analogue stimulus triggering switching at a variable point as someone
pointed out at above.

--

Roger Hayter

Roger Hayter wrote on 11/18/2017 7:59 PM:
rickman wrote:

Roger Hayter wrote on 11/18/2017 4:04 PM:
Stephen Thomas Cole wrote:



Gents, can you please **** off.

If you have nothing to contribute to the discussion why join in at all?

My personal theory as to why few commercial morse keys use reed switches
or optical switches is that that users like to able to connect their
morse keys to a wide range of voltages and impedances, especially if you
include traditional valve equipment. Both technologies are intolerant
of excessive voltages or current compared with a pair of solid metal
contacts. I don't think either speed, latency or debouncing are
significant factors or, at least, they could be designed out.

Not trying to be argumentative, but I'd like to understand the basis of your
point. Why would the three things above not be factors in using mechanical
switches in keys? Bouncing switch contacts do pose an issue for clean
keying of a transmitter, no? So the bouncing has to be smoothed out. That
means adding electronics which means interface specific again, no? I
supposed you could use a high voltage capacitor and no buffer. That would
be a simple RC with the R in series with the key to the controlled point.

But the debouncing is likely to be in the keyed equipment rather than
the key.

Is it? When you talk about working with a multitude of equipment, I would
doubt that is always true.


By the way, i meant jitter[1], latency and that debouncing was no more
significant than for mechanical switches. So I expressed myself rather
inaccurately.

My point is that no one has explained why there would be an more
jitter/latency or whatever with a reed switch than with the sort of
mechanical switch made home brew. In fact, reed switches have very short
debounce and latency times. In at least one spec sheet I found they use a
number which is a fraction of a millisecond.


Maybe I'm not grasping what you are saying. How do you see a simple
mechanical switch being used to control many types of equipment?

BTW, there are transistors available that will switch high voltages and
currents. So a simple interface circuit would serve for use with many types
of equipment and any type of key switch you wish to use.

[1] Not speed which is about the same as latency, but jitter due to the
analogue stimulus triggering switching at a variable point as someone
pointed out at above.

I have seen no reasonable explanation of how a reed switch is any more
analog than a mechanical switch. They are both analog movements of a
mechanism. The only difference is one adjusts a magnetic field while the
other applies pressure to a spring which bends (again in an analog manner)
until it begins to make contact with another spring. Which will have more
jitter? Only a measurement will say and the reed switch has a much lower
time of bouncing, so will not possibly have a noticeable jitter in time of
actuation.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

rickman wrote:

snip

I have seen no reasonable explanation of how a reed switch is any more
analog than a mechanical switch. They are both analog movements of a
mechanism. The only difference is one adjusts a magnetic field while the
other applies pressure to a spring which bends (again in an analog manner)
until it begins to make contact with another spring. Which will have more
jitter? Only a measurement will say and the reed switch has a much lower
time of bouncing, so will not possibly have a noticeable jitter in time of
actuation.

I agree that jitter is not a major issue, but I do think that with a
mechanical switch that human muscles and brain are directly part of the
analogue feedback loop controlling jitter in a way they may not be with
an intervening magnetic link. At least with a straight key, if springs
are part ot the system then your argument is more convincing. This is a
different issue from contact bounce, which occurs after the initial
contact closure.


--

Roger Hayter

Roger Hayter wrote on 11/19/2017 4:45 AM:
rickman wrote:

snip

I have seen no reasonable explanation of how a reed switch is any more
analog than a mechanical switch. They are both analog movements of a
mechanism. The only difference is one adjusts a magnetic field while the
other applies pressure to a spring which bends (again in an analog manner)
until it begins to make contact with another spring. Which will have more
jitter? Only a measurement will say and the reed switch has a much lower
time of bouncing, so will not possibly have a noticeable jitter in time of
actuation.

I agree that jitter is not a major issue, but I do think that with a
mechanical switch that human muscles and brain are directly part of the
analogue feedback loop controlling jitter in a way they may not be with
an intervening magnetic link. At least with a straight key, if springs
are part ot the system then your argument is more convincing. This is a
different issue from contact bounce, which occurs after the initial
contact closure.

Can you explain how the two differ? Just saying they are different isn't an
explanation.

Of course any key has to have a spring for returning the key to home
position. Every key I've seen had at least two adjustments, home position
(and therefore the travel to contact closure) and spring tension.

Bounce time is still and issue because most debounce circuits use a simple
RC to resolve the bounce time and this adds delay to the contact closure
time as seen by the equipment.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

rickman wrote:

Roger Hayter wrote on 11/19/2017 4:45 AM:
rickman wrote:

snip

I have seen no reasonable explanation of how a reed switch is any more
analog than a mechanical switch. They are both analog movements of a
mechanism. The only difference is one adjusts a magnetic field while the
other applies pressure to a spring which bends (again in an analog manner)
until it begins to make contact with another spring. Which will have more
jitter? Only a measurement will say and the reed switch has a much lower
time of bouncing, so will not possibly have a noticeable jitter in time of
actuation.

I agree that jitter is not a major issue, but I do think that with a
mechanical switch that human muscles and brain are directly part of the
analogue feedback loop controlling jitter in a way they may not be with
an intervening magnetic link. At least with a straight key, if springs
are part ot the system then your argument is more convincing. This is a
different issue from contact bounce, which occurs after the initial
contact closure.

Can you explain how the two differ? Just saying they are different isn't an
explanation.

A straight key is a simple proportional muscle movement with feedback
loop via the feel of the contact closure. A key that works via a spring
has a phase change to to the effective energy storage (inductance
analogue) of the spring. The brain is very good at correcting very
slight innacuracies if there is such simple motor feedback circuit,
musicians do it all the time. If there is a magnetic movement or an
optical circuit then a complex delay is included which is no longer a
very simple function of muscular position, Unless the magnetic reaction
of the reed switch is very reproducible or the optical link is very
fast. The human brain can probably have its otherwise very accurate
judgement of cadence harmed by a very few milliseconds of non-linearity.
I do agree it should be possible to arrange such circuits so they are
too fast to notice, but they would have to be very fast.





Of course any key has to have a spring for returning the key to home
position. Every key I've seen had at least two adjustments, home position
(and therefore the travel to contact closure) and spring tension.

The spring in a straight key varies the force but this is linear with
displacement and not out of phase as it is with a springy linkage.



Bounce time is still and issue because most debounce circuits use a simple
RC to resolve the bounce time and this adds delay to the contact closure
time as seen by the equipment.


Most debouncing circuits nowadays would be implemented by digital
device ignoring input for a certain time rather than a simple RC
circuit. Probably a microprocessor.


--

Roger Hayter

Roger Hayter wrote on 11/19/2017 6:27 PM:
rickman wrote:

Roger Hayter wrote on 11/19/2017 4:45 AM:
rickman wrote:

snip

I have seen no reasonable explanation of how a reed switch is any more
analog than a mechanical switch. They are both analog movements of a
mechanism. The only difference is one adjusts a magnetic field while the
other applies pressure to a spring which bends (again in an analog manner)
until it begins to make contact with another spring. Which will have more
jitter? Only a measurement will say and the reed switch has a much lower
time of bouncing, so will not possibly have a noticeable jitter in time of
actuation.

I agree that jitter is not a major issue, but I do think that with a
mechanical switch that human muscles and brain are directly part of the
analogue feedback loop controlling jitter in a way they may not be with
an intervening magnetic link. At least with a straight key, if springs
are part ot the system then your argument is more convincing. This is a
different issue from contact bounce, which occurs after the initial
contact closure.

Can you explain how the two differ? Just saying they are different isn't an
explanation.

A straight key is a simple proportional muscle movement with feedback
loop via the feel of the contact closure. A key that works via a spring
has a phase change to to the effective energy storage (inductance
analogue) of the spring. The brain is very good at correcting very
slight innacuracies if there is such simple motor feedback circuit,
musicians do it all the time. If there is a magnetic movement or an
optical circuit then a complex delay is included which is no longer a
very simple function of muscular position, Unless the magnetic reaction
of the reed switch is very reproducible or the optical link is very
fast. The human brain can probably have its otherwise very accurate
judgement of cadence harmed by a very few milliseconds of non-linearity.
I do agree it should be possible to arrange such circuits so they are
too fast to notice, but they would have to be very fast.

I have no idea what you are talking about with a "complex delay". The reed
switch is a switch just like any other. The mechanical switch has contacts
just like the reed switch. Trying to invoke the human body and nervous
system doesn't explain the difference in the switches you are picturing.

Why wouldn't the optical and reed switches be fast? I've seen optocouplers
that are good for 10 MHz data rates. The reed switches I've seen are rated
for multiple kHz operation. What would make you think either of these are
too slow to provide the contact closure for a mechanical device???

How do you define "very fast"??? Everything I've seen that was mechanical
in nature is *much* slower than electronic devices.


Of course any key has to have a spring for returning the key to home
position. Every key I've seen had at least two adjustments, home position
(and therefore the travel to contact closure) and spring tension.

The spring in a straight key varies the force but this is linear with
displacement and not out of phase as it is with a springy linkage.

Where is a "springy linkage"??? You must be picturing something very
different from what I am picturing.


Bounce time is still and issue because most debounce circuits use a simple
RC to resolve the bounce time and this adds delay to the contact closure
time as seen by the equipment.


Most debouncing circuits nowadays would be implemented by digital
device ignoring input for a certain time rather than a simple RC
circuit. Probably a microprocessor.

Debounce circuits are implemented by the people designing them. Who inserts
a digital device between the key and the radio? Where have you seen such
circuits for a code key? When I searched for such circuits for use with CW
everything I found was RC delays.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998