> This sounds like an identical thread from last August. Just as some
> CW keyer circuits require debouncing when using paddle contacts having
> dissimilar metals, debouncing a bug is a good idea when used in the
> CW + application.
The "dissimilar metals" issue was not one of bounce. It was (and
still is) because many of the new alloys include aluminum or other
metals that produce a semiconducting oxide. That oxide results in
a diode junction at the contacts with an offset (minimum contact
voltage) of about 0.5V which upsets low power CMOS inputs or PIC
devices that rely on differences in voltages to detect left, right,
and "both" paddle closures on a single input pin.
> I suspect that the microHam de-bouncer would be an excellent
> off-the-shelf solution to key bounce problems.
While the K1EL PIC has some debouncing properties, I suspect the
real benefit is due to providing a buffered output that goes
completely to ground ("clean" contacts). All current microHAM
products that use the original K1EL WinKey now contain buffers
(voltage comparators) to raise the switching threshold, eliminating
any problem with offset due to the diode effect.
73,
... Joe Subich, W4TV
microHAM America, LLC.
http://www.microHAM-USA.com
http://groups.yahoo.com/group/microHAM
On 6/19/2010 2:18 PM, Paul Christensen wrote:
>> CW plus was made to faithfully reproduce the keying at very high speeds,
> and has to take the blip seriously.
>
> This sounds like an identical thread from last August. Just as some CW
> keyer circuits require debouncing when using paddle contacts having
> dissimilar metals, debouncing a bug is a good idea when used in the CW +
> application. My preferred method of debouncing uses a Schottky hex buffer
> with a 2N7000 on the key line. In my experience with this circuit, it
> completely smoothes the key contact transitions on a bug.
>
> Another option that may work comes from microHam. K1EL developed a
> PIC-based debouncing circuit powered by a coin battery. It was initially
> used when users of certain Begali paddles were experiencing contact bounce
> resulting from dissimilar metals being used on early Begali key contacts. I
> suspect that the microHam de-bouncer would be an excellent off-the-shelf
> solution to key bounce problems.
>
> http://www.microham-usa.com/Products/Begali.html
>
> Paul, W9AC
>
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
