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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Converting low resistance pot to high resistance ?
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 ? -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#2
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Converting low resistance pot to high resistance ?
Meat Plow wrote:
On Sun, 17 Dec 2006 17:59:35 +0000, N Cook Has Frothed: 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. 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 |
#3
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Converting low resistance pot to high resistance ?
"Meat Plow" wrote in message news On Sun, 17 Dec 2006 17:59:35 +0000, N Cook Has Frothed: 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. -- Pierre Salinger Memorial Hook, Line & Sinker, June 2004 Likewise, no. Arfa |
#4
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Converting low resistance pot to high resistance ?
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#5
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Converting low resistance pot to high resistance ?
"N Cook" writes:
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/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +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. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#6
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Converting low resistance pot to high resistance ?
"N Cook" wrote in message
... 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 ? -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ 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. Reply to address is munged. To reply, remove surplus spaces from: btyguard-dontspam @ yahoo . co . uk |
#7
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Converting low resistance pot to high resistance ?
"C R Briggs" btyguard-dontspam @ yahoo . co . uk wrote in message ... "N Cook" wrote in message ... 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 ? -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ 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. Reply to address is munged. To reply, remove surplus spaces from: 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. Reply to address is munged. To reply, remove surplus spaces from: btyguard-dontspam @ yahoo . co . uk |
#8
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Converting low resistance pot to high resistance ?
Sam Goldwasser wrote:
"N Cook" writes: 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. 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. For more, google foxhole. NT |
#10
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Converting low resistance pot to high resistance ?
Sam Goldwasser wrote:
writes: Sam Goldwasser wrote: "N Cook" writes: 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. 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. For more, google foxhole. 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 |
#11
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Converting low resistance pot to high resistance ?
Sam Goldwasser wrote:
writes: Sam Goldwasser wrote: "N Cook" writes: 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. 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. For more, google foxhole. Not quite what I had in mind. NT |
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