[sdiy] Transistor help

[Pete]

Good stuff! Looking forward to that.

On 4/27/05, Ray Wilson <raywilson at comcast.net> wrote:
> The Precision Resistor PT146 is spec'd for its tempco characteristics. The
> 1K is the stock and therefore cheaper part. The 2Ks are special order and
> are more expensive than the 1K. I just ordered 100 pieces of the 2K and they
> were about $4.40 or so a piece in that quantity. They also have a four week
> lead time.
> 
> I plan to offer the tempco and a VCO board for $25.00 starting in May.
> 
> Cheers
> 
> Ray
> 
> 
> ----- Original Message -----
> From: "Terry Ahrens" <tahrens at scoe.net>
> To: "Pete" <23isgood at gmail.com>; <synth-diy at dropmix.xs4all.nl>
> Sent: Wednesday, April 27, 2005 6:49 PM
> Subject: Re: [sdiy] Transistor help
> 
> > I'm sorry, but I think this in error.
> > The PT 146 is a 1K tempco resistor.  I recently purchased a batch of 10
> > of these from Precision Resistors, and they were (and are still) only
> > $3.10
> > apiece. IIRC, the minimum order is $25 regardless of # of items.
> > Perhaps you were referring to different part#?
> >
> >
> > Pete <23isgood at gmail.com> on Tuesday, April 26, 2005 at 10:33 AM  wrote:
> >
> >
> >>You can get tempco resistors from the site below but they are not
> >>inexpensive. I got a quote for $6.71 each and a 15 piece minimum. I
> >>have not orderd any.
> >>
> >>PT146 2000 ohm 1%
> >>            @25 C
> >>            TC 3500 ppm/degree C
> >>15 pc.min.@$6.71 ea.
> >>
> >>http://www.precisionresistor.com/
> >>
> >>
> >>On 4/26/05, René Schmitz <uzs159 at uni-bonn.de> wrote:
> >>> Hi Fiercefish,
> >>>
> >>> Fiercefish wrote:
> >>> > Hi all, I have just bought a batch of 2n3904's for my soundlab
> >>> > minisynth project, I have a meter that can measure the hFE of them so
> >>> > will this allow me to select matched pairs by choosing those with the
> >>> > closest value? Also I apparently need to find some noisy 3904's for
> >>> > the noise generator, what sort of hFE reading (if any) would yield
> >>> > the most noise eg high or low? Sorry if these seem like dumb
> >>> > questions, I do not know if the hFE value is related to these factors
> >>> > but it is the only method I have of testing them, unless there is
> >>> > another way of course. I'd be greatful for any input or other
> >>> > suggestions, thanks.
> >>>
> >>> hFE is not the right way to select matched pairs. You need to supply a
> >>> constant current through the collector, and you would measure the Vbe
> >>> that you need for that current. What I was always using is to put a
> >>> resistor from collector to V+ and from emitter to V- (with an assumed
> >>> +-15V and the resistors being 150k you get about 100uA.) The base is
> >>> grounded, and you read the voltage between base (GND) and emitter. Find
> >>> the ones that have the reading which most close together.
> >>>
> >>> Cheers,
> >>>   René
> >>>
> >>> --
> >>> uzs159 at uni-bonn.de
> >>> http://www.uni-bonn.de/~uzs159
> >>>
> >>>
> >>
> >>
> >>--
> >>listen to my latest tunes,
> >>
> >>http://www.cubanpetemusic.com/p23%20Litmus.mp3
> >>
> >>www.cubanpetemusic.com
> >>
> >>
> >>
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> 
> 


-- 
listen to my latest tunes,

http://www.cubanpetemusic.com/p23%20Litmus.mp3

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