Good Morning,

I am putting together a winkey keyer kit (I know it is not true homebrew,
but I am just a lowly English teacher). Anyways, I have a variable pot with
three poles and need to know which one is ground. How can I find that out
with a multimeter?

Thanks and 73
G. Doughty
ki4bbl AT cox DOT net

G. Doughty wrote:
Good Morning,

I am putting together a winkey keyer kit (I know it is not true homebrew,
but I am just a lowly English teacher). Anyways, I have a variable pot with
three poles and need to know which one is ground. How can I find that out
with a multimeter?

Thanks and 73
G. Doughty
ki4bbl AT cox DOT net



Do you mean you want to know which tag is attached to the wiper? If that
is what you mean, just measure the resistance between any pair of
terminals, the pair for which the resistance does not change regardless of
position of the pot, neither pin will be the pin you want.

Its usually the centre one.

--

Wing Wong.

Ok, it is the center one. I guess i needed to think outside the box as the
schematic has it showing, from how I interpreted it, one of the ends.
Great! Thanks for the quick response. Now I can install and play. Maybe
you'll here me on 40.

Thanks
greg
ki4bbl AT cox DOT net


"Wing Fong Wong" wrote in message
...
G. Doughty wrote:
Good Morning,

I am putting together a winkey keyer kit (I know it is not true homebrew,
but I am just a lowly English teacher). Anyways, I have a variable pot
with
three poles and need to know which one is ground. How can I find that
out
with a multimeter?

Thanks and 73
G. Doughty
ki4bbl AT cox DOT net



Do you mean you want to know which tag is attached to the wiper? If that
is what you mean, just measure the resistance between any pair of
terminals, the pair for which the resistance does not change regardless of
position of the pot, neither pin will be the pin you want.

Its usually the centre one.

--

Wing Wong.

G. Doughty wrote:
Ok, it is the center one. I guess i needed to think outside the box as the
schematic has it showing, from how I interpreted it, one of the ends.
Great! Thanks for the quick response. Now I can install and play. Maybe
you'll here me on 40.

Is what you're building the same thing as on
http://k1el.tripod.com/winkey.pdf ?

If so, it really doesn't matter! You use the center terminal (the
wiper) and one end, it doesn't matter which end. The consequences of
getting it "wrong" are that the control will work "backwards" - you'll
turn the pot counter-clockwise to speed up your Morse, instead of
clockwise. If that happens, you can fix it by using the other end
terminal. You won't damage anything by getting it wrong.

================================================== ====================

In general, for any other future construction projects you may get
involved in... it is VERY unusual for the wiper of a pot to be
connected to ground. It does happen - it would be acceptable to do so
in this Winkey circuit and I have seen others - but it is VERY rare. In
some circuits, grounding the wiper when you shouldn't could result in
damage to the pot (and possibly other parts). And almost always, the
circuit won't work, or at least won't work properly.

Getting the two ends mixed up is far less dangerous. The worst
consequence is the same as it is with the Winkey: the control will work
backwards and you can fix it by swapping the ends.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

"G. Doughty" wrote in message
news:3RA_d.65108$7z6.28233@lakeread04...
Ok, it is the center one. I guess i needed to think outside the box as
the
schematic has it showing, from how I interpreted it, one of the ends.
Great! Thanks for the quick response. Now I can install and play. Maybe
you'll here me on 40.

Thanks
greg
ki4bbl AT cox DOT net

I am not sure the other poster understood your question- especially given
your response. None of the terminals are grounded- you do that when you
wire it into the circuit. If this is the speed control and you choose the
wrong end- it will function backwards- just reverse the 2 end connections.

Dale W4OP

"G. Doughty" wrote:

Good Morning,

I am putting together a winkey keyer kit (I know it is not true homebrew,
but I am just a lowly English teacher). Anyways, I have a variable pot with
three poles and need to know which one is ground. How can I find that out
with a multimeter?

No terminal of a pot is grounded inside the pot. It is just a chunk
of resistance with a terminal on each end sliding contact in the
middle.

I think you need to connect the bottom terminal (when you are looking
at the end of the shaft and the terminals are to the left) to ground
and the middle one (the wiper) to the speed control input (S).
See page 13 of:
http://k1el.tripod.com/winkey.pdf

--
John Popelish

G. Doughty wrote:

Good Morning,

I am putting together a winkey keyer kit (I know it is not true homebrew,
but I am just a lowly English teacher). Anyways, I have a variable pot with
three poles and need to know which one is ground. How can I find that out
with a multimeter?

Thanks and 73
G. Doughty
ki4bbl AT cox DOT net


Ditto all the comments already made (except that you probably want to
ground one of the ends rather than the wiper), plus: A potentiometer is
nothing more than a strip of resistive material with terminals at each
end and a movable contact attached to the knob somewhere in the middle.
The movable contact is called the "wiper" because, well, it wipes.

If you ignore audio taper pots the resistance between any two points
along the length of the strip is proportional to the distance between
the points. So if you have a 2" long strip in a 20k-ohm pot, and you
place the wiper 1/2 inch away from one end, you'll see 5k-ohms between
the wiper and that end (and 15k-ohms between the wiper and the other end).

Potentiometers almost always come with three leads, and the leads are
almost always arranged so that the middle lead is the wiper -- the only
exception I know is with some precision multi-turn pots, but you can
ignore those. The drawing below shows the correspondence between a
schematic drawing of a pot (euro-style, kinda -- just take the box to be
the usual squiggly line) and a drawing of a panel-mount pot.


Schematic
symbol
(euro-style) Physical
drawing
End1 (poor)
|
.-.
| |-- Wiper
| | / \ - End1
'-' | O |- Wiper
| \ / - End2
End2
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de


--

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