[CW] Debouncing Vibroplex Contact

[D.J.J. Ring, Jr.]

https://www.dl6zb.de/MORSE_KEYER/vibroplex_debouncing.html

MORSE BUG DEBOUNCING
Debouncing a Vibroplex Blue Racer
by DL6ZB, Rolf Heine

[image: Vibroplex Blue Racer]


If you are owner of one of those beautiful and famous old fashioned bug
keyers, you might have observed a problem while sending morse dits called
bouncing. Bouncing is a fundametal problem with every switch in electronic
devices. Engineers faced those problems from the beginning on since
switches and relays where invented. Several debouncing methods were
developed over the years. One solution is to connect a low-pass filter
between the switch (morse-bug) connectors. Other solutions are based on
digital methods. I tried to solve the problem the simplest way possible.

My solution is this: just connect a 330 nF non-polarized capacitor between
the bug's connectors. Be careful with the voltage rating of the capacitor
if you use the bug with an ancient tube transmitter! See the manual before
installing the capacitor. A 10 kOhm impedance of the keyer input was
assumed which should be ok for most transceivers. If your transmitters
keyer impedance is far away from the 10k you should reconsider the correct
capacitors values for a succesful debouncing of your mechanic keyer.

A good idea might be to use a 220 nF capacitor across the bug connectors
and another 100 nF capacitor inside an usual 6,3 mm keyer jack. This can
give an additional amount of RF filtering at the transmitters key plug.

Here is the result of this debouncing method which is ok at speeds of about
20-30 WPM. At higher speeds the debouncing method should be improved.


[image: Pic 1] <https://www.dl6zb.de/MORSE_KEYER/%20MAP001.BMP> Picture 1
This picture shows dits from the Vibroplex Blue Racer at approx. 20 WPM
without debouncing.
The falling edge shows dit-bounces.
[image: Pic 2] <https://www.dl6zb.de/MORSE_KEYER/%20MAP002.BMP> Picture 2
After zooming in the dit-bounces are clearly visible.
[image: Pic 3] <https://www.dl6zb.de/MORSE_KEYER/%20MAP003.BMP> Picture 3
This picture shows the shape of the dits after installing a 330 nF
capacitor across the bug's connections. Again the speed is about 20 WPM.
Oscilloscope settings are the same as in picture 1.
[image: Pic 4] <https://www.dl6zb.de/MORSE_KEYER/%20MAP004.BMP> Picture 4
Compared with picture 2 there's an improvement of debouncing. Those small
bounces are tolerable for me. Oscilloscope settings are the same as in
picture 2.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/cw/attachments/20231204/023d56ce/attachment.html>