Re: Question? UCN5804

I've worked in electronmics for over 30 years. Most electronic
circuits do not need 1% or even 2% tolerances. Many power resistors
are 10% or envn 20% tolerance. If it calls for a 5K Ohm, 5 W
resistor, I'm sure a 5.1K (a +2% increase over 5K) would work equally
well. If I were creating a higher wattage resistor by paralleling 5
1W ones, I would definitely use five of the same value. Five 5.1K,
1W resistors in parallel would work very well and the currents
through them would be better balanced. And besides, the resistors
you are buying are likely 10% tolerance anyway. That means their
actual values are between 4.59K and 5.61K. Heck, 5 4.7Ks would work
quite well.

These loose tolerances are why they put trimmer pots in many
electronic circuits.

Another good source for electronic components is Newark Electronics.
They're a lot older than Digi-Key and carry or can get almost
everything. www.newark.com

Paul A.


--- In CAD_CAM_EDM_DRO@yahoogroups.com, Harvey White <madyn@i...>
wrote:

> On Wed, 2 Jul 2003 05:03:25 -0700 (PDT), you wrote:
>
> >On Tue Jul 1 21:40:34 2003 ben_englund wrote:
> >
> >>> > > From: k00lmon <k00lmon@y...>
> >>> > >
> >>> > > I'm trying to learn how to operate a stepper motor by

making my

> >>own
> >>> > > circuit. I have read through "The Robot Builder's Bonanza"

by

> >>Gordon
> >>> > > McComb and found a circuit utilizing a UCN5804 IC to

control a

> >>> > > stepper motor. What I don't understand is that the circuit

has

> >>> > > resistor components that were indicated as 2 to 5 watts at

1K!

> >>Where
> >>> > > do I find 2 watts resistors? Is it easier for me to learn

how to

> >>> > > control a stepper motor by just buying a kit? Are there any
> >>kits out
> >>> > > there that teaches u the basics of controlling stepper

motors

> >>that
> >>> > > anyone could recommend? Thanks for reading.
> >>
> >>Radio shack used to carry 2 watt resistors but I see they are

getting

> >>away from components lately. Kind of sad... Should still be able

to

> >>buy them on the web site or through the catalog though. Or order
> >>from Digi-Key, they are real good. I get small orders the next

day

> >>and free shipping. Hope this helps.
> >>
> >>
> >>Ben Englund
> >
> >Or, you can make a 5 Watt, 1K resistor, by taking five 1 Watt, 1K

resistors,

> >and soldering them in parallel with each other.
>
> No, you can't.
>
> You end up with a 200 ohm resistor.
>
> Do this with 4 5.1K ohm resistors and 1 4.7 k resistors. That will
> get you as close as you can get. Each of the resistors needs to be

1

> watt. The 4.7 K resistor will get fractionally warmer.
>
> (You end up 400 plus and 300 minus, which when averaged out, is

about

> 20 ohms plus. close enough)
>
>
> Must have been really early for you. <grin>
>
> Harvey
>
>
> >
> >Bill