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Author: Johnny ChangJohnny Chang
Date: Mar 30, 2008 23:57
does anyone have any general guidelines and perhaps some tutorials for
allegro SI for designing around crosstalk?
my knowlege on the subject:
i've taken various E&M courses so i know the theory behind it, and am
taking a digital systems class so i've ventured into the experimental
side, but its mostly been with transmission lines and not pcb traces
with hundreds of nets. what can be done besides ground/power planes
and thick/far apart traces?
i only know a bit about bypass caps, heard something about parallel
plane pairs(?) and routing topology (something about short nets acting
as shields to long parallel nets). can anyone explain those? and
tutorials / documentation examples for putting it all together in
software (how to use constraints and stuff?)
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2 Comments |
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Author: Trs80Trs80
Date: Mar 30, 2008 16:17
If given MTBF and standard deviation can the reliabilty be predicted at a
defined operational range using Excels Normaldistribution?
say mtbf = 50, sd= 20, then plug in the operating duration.
NORMDIST(operating duration, 50, 20, true).
Is that a way to calculate reliability at a specifed duration?
thanks!
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no comments
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Author: amp isamp is
Date: Mar 30, 2008 02:44
I have a 3 section 3 phase MCB rated at 25A.
Is this 25A total or 25A on each phase?
TIA.
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7 Comments |
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Author: AdityaAditya
Date: Mar 29, 2008 22:49
Hullo.
I was asked this question during my Lab viva.
" There is a circuit with SCR, without the gating circuit of the SCR
connected ( Assume it to be isolated so that the firing of the SCR
wont occur anyway due to it. ) The present Voltage source (V1) is a
100V rms sine supply. Presently, the SCR doesnt condect, i.e the SCR
is OFF. The V1 is disconnected, another Voltage source (V2), 100 V
rms, sine o/p is connected. The SCR now conducts !!! How ??? "
The answers given by me were
1. The new Vsource must have given a step i/p and hence the Voltage
breakdown ( dv/dt) of the SCR must have occured. ( He shook his head,
as in NO )
2. The temperature must have changed during the process of changin of
Vsource. ( Again shook his head.)
3. The internal resistance of the V2 must be less so that it gives
somewht higher o/p to cause breakdown of SCR.. ( Again the wrong
answer he said. )
So, WHat else can it be ?????
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7 Comments |
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Author:
Date: Mar 28, 2008 10:33
Planning a new addition to my current shop. This addition will require
running 4 new circuits from my main gutter.
A 60a 480v, 40a 480v and 2 - 60a 240v.
I have to route these about 100' before they need to branch. Does code
prohibit running all of these circuits in one conduit?
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13 Comments |
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Author: Gerald NewtonGerald Newton
Date: Mar 27, 2008 10:52
The new definition of Vending Machines in 422.51 expands the meaning
to include some rather unusual machines. For instance the amusement
rides for children in shopping malls, massage chairs in malls, gaming
machines in theatres, and the gambling machines found in bars and in
Los Vegas are now vending machines.
The new sentence reads: The term vending machine means any self-
service device that dispenses products or merchandise without the
necessity of replenishing the device between each vending operation
and is designed to require insertion of a coin, paper currency, token,
card, key, or receipt of payment by other means.
The IAEI Analysis of Change Book describes children's amusement rides
at malls as an example. Evidently, the product dispensed is the
ride. The rule does require that only cord and plug connected vending
machines require GFCI protection.
The rule also is retroactive for older vending machines manufactured
prior to January 1, 2005. These existing machines will have to be
GFCI protected if the 2008 NEC is adopted.
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no comments
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Author: TomTom
Date: Mar 27, 2008 02:52
Subscribe FREE Engineering & Technical Magazine at www.calculatoredge.com
also check out free calculator tools you an use for your design /
evaluation purpose.
Tom
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no comments
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Author: Robert HubbardRobert Hubbard
Date: Mar 26, 2008 14:00
On Mar 21, 10:10Â am, Alan McKenney yahoo.com> wrote:> About 10 years or so ago, the catenary on at least
> some parts of the North-East Corridor were replaced
> with what was touted as "Eurpean-style" catenary.
> It was never explained exactly what was meant by that,
> but it was claimed that the "European" catenary was
> much better than the old.
>
> I recall from my years in Europe that one of the most
> distinctive things about the catenary there was that
> the wire was tensioned using weights -- the wire
> would be run out to a pulley, with weights hanging off
> the larger diameter wheel to apply torque and thus tension.
>
> This meant that the tension would remain constant
> as the wire expanded and contracted.
>
> By contrast, in the Northeast (USA), the contact wire is
> just tied off to posts at either end. Â As far as I have
> been able to tell in my occasional trips around here, ...
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14 Comments |
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