# Converting low resistance pot to high resistance ?

N

#### N Cook

Jan 1, 1970
0
Over the years I've often done the opposite by putting a resistor between
wiper and low end and another from wiper to high end.
just in case I've missed something over the years is there a way of say
converting a 20K pot to a 100K pot, with full range from bottom to top ?

M

#### Meat Plow

Jan 1, 1970
0
Over the years I've often done the opposite by putting a resistor between
wiper and low end and another from wiper to high end.
just in case I've missed something over the years is there a way of say
converting a 20K pot to a 100K pot, with full range from bottom to top ?

No.

M

#### [email protected]

Jan 1, 1970
0

How can you make a 100k pot when youve got a variable R that only
covers 20k. The answer is you cant. But there are 2.5 buts:

1. if its a ganged pot its poss to put the 2 tracks in series, doubling
R. But you cant then have a tapoff that moves anywhere along that track
length. However in many apps its ok to use a 2 terminal variable R, so
this will sometimes do.

2. You may be able to cut the track width down to increase R. Lot of
hassle though!

3. Some ccts can be tweaked so they run happily with a lower value pot.

But in these days of material overflow, its hard to think of any reason
to do any of the above now.

NT

A

Jan 1, 1970
0
Meat Plow said:

Likewise, no.

Arfa

M

#### [email protected]

Jan 1, 1970
0
How can you make a 100k pot when youve got a variable R that only
covers 20k. The answer is you cant. But there are 2.5 buts:

1. if its a ganged pot its poss to put the 2 tracks in series, doubling
R. But you cant then have a tapoff that moves anywhere along that track
length. However in many apps its ok to use a 2 terminal variable R, so
this will sometimes do.

2. You may be able to cut the track width down to increase R. Lot of
hassle though!

3. Some ccts can be tweaked so they run happily with a lower value pot.

But in these days of material overflow, its hard to think of any reason
to do any of the above now.

NT

or lots of cuts across the track 2/3 of the way on alternate sides will
convert a straight track into a wiggly hence longer and higher R one.
All depends if youre in a shop or holed up in pow camp.

NT

S

#### Sam Goldwasser

Jan 1, 1970
0
N Cook said:
Over the years I've often done the opposite by putting a resistor between
wiper and low end and another from wiper to high end.
just in case I've missed something over the years is there a way of say
converting a 20K pot to a 100K pot, with full range from bottom to top ?

Not with only passive components.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

C

#### C R Briggs

Jan 1, 1970
0
N Cook said:
Over the years I've often done the opposite by putting a resistor
between
wiper and low end and another from wiper to high end.
just in case I've missed something over the years is there a way of
say
converting a 20K pot to a 100K pot, with full range from bottom to top
?

Add 4 off 20K fixed resistors in series, with a shorting switch across
each (or a rotary selector switch). You should get "steps" of 20K with
a 20K range adjustment in each step (i.e. 100K variable down to 80K; 80K
variable down to 60K: 60K variable down to 40K: 40K variable down to 20K
& 210K variable down to 0).

--
Regards,

C R Briggs.

btyguard-dontspam @ yahoo . co . uk

C

#### C R Briggs

Jan 1, 1970
0
C R Briggs said:
Add 4 off 20K fixed resistors in series, with a shorting switch across
each (or a rotary selector switch). You should get "steps" of 20K
with a 20K range adjustment in each step (i.e. 100K variable down to
80K; 80K variable down to 60K: 60K variable down to 40K: 40K variable
down to 20K & 210K variable down to 0).

--
Regards,

C R Briggs.

btyguard-dontspam @ yahoo . co . uk

DOH!

Should of course be:

i.e. 100K variable down to 80K; 80K variable down to 60K: 60K variable
down to 40K: 40K variable down to 20K & 20K variable down to 0.

--
Regards,

C R Briggs.

btyguard-dontspam @ yahoo . co . uk

M

#### [email protected]

Jan 1, 1970
0
Not with only passive components.

that sounds like a challenge if ever I heard one

Take a 100k resistor, scrape the paint off one side. Cut a hole in the
track to fit it in, glue it there, and connect the leads to the ends of
the track. Paint over the remaining track. Now, if its all set up
right, the 100k R acts as the new track.

NT

S

#### Sam Goldwasser

Jan 1, 1970
0
that sounds like a challenge if ever I heard one

Take a 100k resistor, scrape the paint off one side. Cut a hole in the
track to fit it in, glue it there, and connect the leads to the ends of
the track. Paint over the remaining track. Now, if its all set up
right, the 100k R acts as the new track.

Not quite what I had in mind.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

K

#### Ken Weitzel

Jan 1, 1970
0
Sam said:
Not quite what I had in mind.

Hi...

OK, another way to do it, then.

Dis-assemble the control. Attach your meter across the outside
contacts. With a piece of fine sandpaper start sanding away at
the track. Stop when the meter says 100k. It may or may not
be linear, dependent on your sanding abilities.

Take care.

Ken

M

Jan 1, 1970
0

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