electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
 Forum index » DIY Hardware and Software » Klee sequencer
0,1 % resistors
Post new topic   Reply to topic Moderators: Scott Stites, Uncle Krunkus, v-un-v
Page 1 of 1 [10 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
eXisteNz



Joined: Jun 08, 2010
Posts: 48
Location: Italy

PostPosted: Thu Mar 21, 2013 6:30 pm    Post subject: 0,1 % resistors Reply with quote  Mark this post and the followings unread

Hello!
i'm approaching to build pcbs, i wonder which malfunction might arise if i put 1% in place of 0,1% resistors? and....i have not a fluke for hand match resistor, but a DMM...i read about wheatstone bridge technique for selecting 0,1 values.... anyone know well this procedure?
cheers
Nico
Back to top
View user's profile Send private message
blue hell
Site Admin


Joined: Apr 03, 2004
Posts: 24079
Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320

PostPosted: Thu Mar 21, 2013 7:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

Your range or tuning may be off with 1% when 0.1% was specified - when nothing was specified usually 5% is assumed and 1% will be fine, or overkill - depending on pint of view. 0.1% is rare really.

Fluke is just a brand for DMMs, so that's fine prolly.

Re. Wheatstone, yes I know all the details Laughing please zoom in a bit, maybe point to a website you saw and have questions about?

_________________
Jan
also .. could someone please turn down the thermostat a bit.
Posted Image, might have been reduced in size. Click Image to view fullscreen.
Back to top
View user's profile Send private message Visit poster's website
Uncle Krunkus
Moderator


Joined: Jul 11, 2005
Posts: 4761
Location: Sydney, Australia
Audio files: 52
G2 patch files: 1

PostPosted: Thu Mar 21, 2013 10:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

From what I remember,
The .1% resistors (i think only about 10 or so are specified as such) just need to be within .1% of each other. They are for gain matching the op-amp stages. They don't have to be spot on the value, just the same as each other.
So,...buy about 100 or so 1% metal film resistors of the value quoted (eg 100K), and, using your DMM, sort them into piles which are matched to .1% (ie 99.8, 99.9, 100, 100.1, 100.2, etc. When one of the piles reaches the number you need, that's the pile you use.

_________________
What makes a space ours, is what we put there, and what we do there.
Back to top
View user's profile Send private message Visit poster's website
eXisteNz



Joined: Jun 08, 2010
Posts: 48
Location: Italy

PostPosted: Fri Mar 22, 2013 4:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Yes i understand, but i can't match them each other because my DMM on 100k range have an accuracy of 1ohm only (i.e it can read only 99kohm 100kohm 101kohm; and not 99,1 99,2)....

As regarding W.Bridge.. if i need to match each other only, i don't need to put a potentiometer, but only 3 resistor of known 0.1 accuracy value.... is that right?

I found these resistors, and i wonder if you could identificate as precision one since i dont' know which kind are these on the photo i'm attaching, i have 7 of 10k and 8 of 100k...

Then other question is: can i use 3 resistors of the same values on the bridge? i.e. can i use my 3 100k green precision resistors (if they are) as R1, R2, R3 for match the other 1%metalfilm 100k (Rx)?

And lastly: then i measure voltage between points that aren't connected at 9v battery voltage source is that right?

Well i think that answering these questions could be a good starting point to study calculus to do next...

Sorry for my poor english and thank you sooooo much for your patience!

nico


resist.jpg
 Description:
 Filesize:  52.08 KB
 Viewed:  594 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

resist.jpg


Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 2177
Location: Chicago
Audio files: 16

PostPosted: Fri Mar 22, 2013 5:41 am    Post subject: Reply with quote  Mark this post and the followings unread

For a Wheatstone if all you're doing is matching *to each other* don't you only need two super-accurate resistors for the top half of the bridge?

Having the third is so you can be certain that all your matches match that third one, as I understand it.... ??

I have doubt because I haven't done this....
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 2177
Location: Chicago
Audio files: 16

PostPosted: Fri Mar 22, 2013 7:49 am    Post subject: Reply with quote  Mark this post and the followings unread

So I did some more searching and this seems like a fairly definitive source:

http://www.muffwiggler.com/forum/topic-61933.html


one question I have though is....would it be possible for your initial go round to do something more like this to get started:

take the top two resistors, put them on either side of a high quality trimmer, put a voltage across the whole thing and then adjust the trimmer to as close to exactly 50% of the voltage as you can manage. This gives you a solid starting point, probably better than starting with two random 1% resistors.

build the rest of the bridge, put a trimmer at the bottom as well. Run your source voltage across the wipers of the two trimmers, and adjust the lower one until you get a balanced bridge (the other measurement is 0).

Then swap out one of the lower legs repeatedly, noting the difference measurement, and sorting by that measurement, with the idea that any that are at the same difference value must be high degree matches.

For future use, take three that you match this way and omit the trimmers.


I doubt that's simpler or faster than Ian's method (probably not, I don't think I would dare to compare my lack of experience with his years doing this stuff), but it had occurred to me before reading the Muff's article and I wanted to ask if I'm being logical here.
Back to top
View user's profile Send private message
eXisteNz



Joined: Jun 08, 2010
Posts: 48
Location: Italy

PostPosted: Fri Mar 22, 2013 8:24 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks elmegil for your ideas and link, i'll definately try them, i really don't know if it's works because i know far less than you about this technique....
COuld you please try to identificate which type of resistor is the one i've attached above in the photo? Since i have a 7-8 100k like that, i was wondering if they're precision military grade resistors....
thank you!
Back to top
View user's profile Send private message
elmegil



Joined: Mar 20, 2012
Posts: 2177
Location: Chicago
Audio files: 16

PostPosted: Fri Mar 22, 2013 8:45 am    Post subject: Reply with quote  Mark this post and the followings unread

Unfortunately I've never seen that kind of resistor before....
Back to top
View user's profile Send private message
capicoso



Joined: Nov 19, 2012
Posts: 128
Location: Argentina

PostPosted: Wed Mar 27, 2013 10:10 am    Post subject: Reply with quote  Mark this post and the followings unread

eXisteNz wrote:
Yes i understand, but i can't match them each other because my DMM on 100k range have an accuracy of 1ohm only (i.e it can read only 99kohm 100kohm 101kohm; and not 99,1 99,2)....



That's weird, is it an old one or something? Even my 5usd cheapest DMM can read 100,1 99,9
Back to top
View user's profile Send private message
eXisteNz



Joined: Jun 08, 2010
Posts: 48
Location: Italy

PostPosted: Thu Mar 28, 2013 1:25 am    Post subject: Reply with quote  Mark this post and the followings unread

Well it's a weird cheap new Tenma DMM model 72-7925:

RANGE RESOLUTION ACCURACY
200R 0.1R +-(0.8%+3)
2K 1R +-(0.8%+1)
20K 10R "
2M 1K "
20M 10K +-(1%+2)

DISPLAY MAX: 1999

So to measure 100k i have to go in 2M range having only 1k of resolution Sad
Anyway i've hand selected them with weathstone bridge and all was ok..
After a day i've remeasure with this DMM to see if at least all 25 resistors measure the same: 21 of them measure steady 98 but there's 4 measuring 99!!! Russian Roulette dunno
At the end now i'm ordering 25 100k 0.1% resistor from my supplier!
Definately i have to buy a new DMM!
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites, Uncle Krunkus, v-un-v
Page 1 of 1 [10 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » Klee sequencer
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use