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 Forum index » DIY Hardware and Software » Developers' Corner
2k Tempco advice
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ejr27233



Joined: Feb 08, 2010
Posts: 44
Location: UK

PostPosted: Sun Feb 26, 2012 6:41 am    Post subject: 2k Tempco advice
Subject description: Options to replace 2k tempco
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I'm about to build 2 Buchla 258ish VCO's and need 2k Tempco's.
I've got 1k ones so the options are....

a, Put 2 1k tempco's in series
b. Put a 1k tempco and a 1k 1% metal film resistor in series.

or at a push
c, Order 2k tempco's from USA (not keen to do)

Which is the best option???

Any advice greatfully recieved
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Sebo



Joined: Apr 27, 2007
Posts: 540
Location: Argentina

PostPosted: Sun Feb 26, 2012 6:55 am    Post subject: Reply with quote  Mark this post and the followings unread

I think that two 1K tempcos in series will work OK. The x0xbox uses two 1K tempcos in series.
1K tempco + 1K metal film will not work for sure, as the temperature coeficient will be a lot lower than needed.

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ejr27233



Joined: Feb 08, 2010
Posts: 44
Location: UK

PostPosted: Fri Mar 02, 2012 11:39 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for your help

Regards

John
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L´Andratté



Joined: Sep 23, 2012
Posts: 60
Location: Hamburg, Germany
Audio files: 5

PostPosted: Sat Jan 19, 2013 4:41 pm    Post subject: Reply with quote  Mark this post and the followings unread

Funny, I have the same question-
Since those tempcos are not really cheap, wouldn´t it be possible to just lower the input resistors from 100 to 47k (same relation gain 1/50)?
I´ll try it...

rabbit
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rogerlatur



Joined: Dec 22, 2012
Posts: 118
Location: france

PostPosted: Mon May 20, 2013 5:26 am    Post subject: Reply with quote  Mark this post and the followings unread

L´Andratté wrote:
Funny, I have the same question-
Since those tempcos are not really cheap, wouldn´t it be possible to just lower the input resistors from 100 to 47k (same relation gain 1/50)?
I´ll try it...

I am curious if you did try?
Is there any replacement then?
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L´Andratté



Joined: Sep 23, 2012
Posts: 60
Location: Hamburg, Germany
Audio files: 5

PostPosted: Mon May 20, 2013 5:52 am    Post subject: Reply with quote  Mark this post and the followings unread

Yes and no...

I did build it and it gave exponential response and mediocre scaling was there, but not optimal, maybe due to other things? I don´t know, I guess the problem with the 47k is about the input impedance, maybe there´s some tiny voltage loss?

The difficulty might be the same cv would give different notes from different osc.s! {EDIT: check next post}

Sorry I´m only autodidactic halfwit Confused

Good reading:

*** ELECTRONOTES S019:scroll down here
http://electronotes.netfirms.com/free.htm

***http://www.uni-bonn.de/~uzs159/index.html

***first article under
"Projects and Misc Files"

http://home.comcast.net/~ijfritz/misc_lnk.htm

Last edited by L´Andratté on Mon May 20, 2013 6:31 am; edited 1 time in total
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L´Andratté



Joined: Sep 23, 2012
Posts: 60
Location: Hamburg, Germany
Audio files: 5

PostPosted: Mon May 20, 2013 6:29 am    Post subject: Reply with quote  Mark this post and the followings unread

Check especially the 2nd link halfway down, it´s there!
54k:1k at 1% tolerance! Embarassed
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rogerlatur



Joined: Dec 22, 2012
Posts: 118
Location: france

PostPosted: Wed May 22, 2013 10:53 am    Post subject: Reply with quote  Mark this post and the followings unread

L´Andratté wrote:
Check especially the 2nd link halfway down, it´s there!
54k:1k at 1% tolerance! Embarassed

I see.
This page is very instructive, and I will check also the other links. Thank you very much!
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