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