[sdiy] Current source for tempcos in small quantities

[Ken Stone]

I have quite an article on these Philips KTY8x  (x= 1...4) from 1983
"electronic components and applications" though when I looked into finding
them recently, I came up blank :)

Ken

>Sorry to drop in,
>I think all this Farnell stuff is no wire wound PTC,
>but some semiconductor stuff.
>So you can go as well with Philips KTY8x  (x= 1...4).
>
>They are easier to obtain. And they are small, look like a 1N4148
>diode.
>
>The tempco is too high (8000ppm from my head),
>but this is a good thing since it can always be made
>lower, but not higher.
>
>Some of these guys are unipolar (i think #4), so watch out!
>
>These days some of these special items seem to vanish,
>though there seem to be some manufacturers who 
>live from bringing "obsolete" stuff back again,
>like ON semiconductor.
>
>Better buy a pile before they are completely gone.
>
>
>m.c.
>
>
>
>-----Original Message-----
>From: Ian Fritz [mailto:ijfritz at earthlink.net]
>Sent: Montag, 10. März 2003 04:38
>To: harrybissell
>Cc: Jozsef Baksay; synth-diy at dropmix.xs4all.nl
>Subject: Re: [sdiy] Current source for tempcos in small quantities
>
>
>Hi Harry --
>
>At 04:46 PM 3/9/2003, harrybissell wrote:
>>I thought the Q81 were 3300 ppm/K ???
>
>The info I have says 3500 ppm/K. There is some +/- tolerance on this, but I 
>don't remember what. To get the best compensation I have needed to add a 
>series resistance roughly consistent with the 3500 value.
>
>>In the common use of the tempco (shunting the base of the expo tranny)
>>will adding the non-tempco in series cause any problems with the value...
>>or do you just change the series resistor to the base to match ?
>
>You have to change the other leg of the voltage divider (whichever 
>configuration) proportionately.  In other words, you have to readjust the 
>tracking.
>
>   Ian
>
>
>
_______________________________________________________________________
Ken Stone   sasami at hotkey.net.au  
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
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