|
Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
|
Thread Tools |
8th Jan 2017, 1:38 pm | #1 |
Nonode
Join Date: Oct 2014
Location: West Midlands, UK.
Posts: 2,181
|
Changing the value /mode of pots
My post https://www.vintage-radio.net/forum/...d.php?t=132814
reminded me of an article in the back pages of an old ETI Circuits Book No1, published in 1976 .Those pages are long gone, thanks to an old rescue Collie who decided that making a bed in my electronics mags for her ( unknown to me when I homed her) litter of pups. Dog of good taste ? One idea was to change the value/mode of a pot by fitting a parallel resister . I've always been tempted to have a look at this idea from a mathematical view. Anyone remember this article / looked at it's ideas in detail? |
8th Jan 2017, 1:44 pm | #2 |
Banned
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
|
Re: Changing the value /mode of pots
I looked at doing this and asked on the forum. Was told it was not a good idea and that it would not achieve what I wanted, i.e. a changed value pot either log or lin.
|
8th Jan 2017, 1:45 pm | #3 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
|
Re: Changing the value /mode of pots
Not seen that particular article but modifying a pots behavior has been covered a lot on the forum, here's a popular link to the subject:
http://www.geofex.com/article_folder...s/potscret.htm Lawrence. |
8th Jan 2017, 2:52 pm | #4 |
Nonode
Join Date: Oct 2014
Location: West Midlands, UK.
Posts: 2,181
|
Re: Changing the value /mode of pots
I'm more interested in the content of the article. At the time, I glanced over it. But these days it might have more interest. Thanks, ms660.
|
8th Jan 2017, 6:32 pm | #5 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,223
|
Re: Changing the value /mode of pots
"Slugging" a linear-track audio level pot to obtain a log law is a legitimate technique. The curve is determined by the parallel combination of the added resistor from slider to earth and the following circuit load impedance.
I remember some old Neve mixing consoles used a preset trimmer that was adjusted to give the required fader law. |
9th Jan 2017, 1:04 am | #6 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,340
|
Re: Changing the value /mode of pots
I've got the book somewhere in the shed.
If i can find it, I'll scan the page for you. Terry |
11th Jan 2017, 2:28 am | #7 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,340
|
Re: Changing the value /mode of pots
Found the book, no log/lin article in this one.
I do remember seeing something along those lines in another book/mag somewhere. Just to confirm I have the correct book, front cover below. |
11th Jan 2017, 4:07 pm | #8 |
Nonode
Join Date: Oct 2014
Location: West Midlands, UK.
Posts: 2,181
|
Re: Changing the value /mode of pots
TERRY- that is the book.I raised the point as I thought other members might like a look at this article.
Your shed must be a lot better than mine. BUT then, I had an old Collie looking to make a bed for herself away from a brood of hungry pups ---and my stack of mags must have looked a decent den ---possibly a dog with a lot of taste Last edited by Oldcodger; 11th Jan 2017 at 4:15 pm. |
11th Jan 2017, 11:13 pm | #9 | |
Nonode
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 2,198
|
Re: Changing the value /mode of pots
Quote:
Martin
__________________
BVWS Member |
|
12th Jan 2017, 10:44 am | #10 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,340
|
Re: Changing the value /mode of pots
Don't bet on it, I know I've got all sorts in there, but finding it is the problem. At least the dog here knows better than to get into my stuff, although lengths of wire intrigue him.
The article may have been in one of the others from the series, it rings a bell (we need a smiley with a ringing head ). They are in there (the shed) somewhere, will keep an eye out for them. Terry |
12th Jan 2017, 12:37 pm | #11 | |
Octode
Join Date: Jul 2009
Location: Carmel, Llannerchymedd, Anglesey, UK.
Posts: 1,509
|
Re: Changing the value /mode of pots
Quote:
Les. |
|
14th Jan 2017, 2:46 pm | #12 |
Heptode
Join Date: Mar 2008
Location: Forest of Dean, Gloucestershire, UK.
Posts: 648
|
Re: Changing the value /mode of pots
Well after a bit of digging in my archive (and even more messing about with the scanner to get it to PDF) I've found the attached, which came from Elektor nearly 40 years ago. It seems to cover the ground fairly well so I hope that it proves useful.
Hugh |