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Re: Digest Number 134
Jim Purcell
Himont,
As some-one has already suggested that charge is stored on the plates and that the dielectrics is a medium for the charge transfer...But this is also so of air capacitors, but both are used at higher frequencies where low capacitance is less important than having a self healing dielectric. Of course there are limits even to this trait. I once had to replace some really large air dielectric capacitors in a radio transmitters that had been victims of ball lightening. It danced between the plates and literally fuzed some of them together. Jim |
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Re: newbie inquiry
开云体育Please
tell me that 12VDC ~ 2Amps ~ 230 Watts (PC power Supply) don't kill , as i've
tried it. (ahhhhh)
?
Does
anyone have a chart that tells me when to touch & when to wear rubber
gloves
imran
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Re: Digest Number 134
Jim Purcell
d,
I'd like to know, myself, why people think that the charge is stored in theSorry, but the charge is stored in the dielectric. That's why the amount of capacitance depends in part on the kind of dielectric. A conductor will not store a charge, only provide a path for it. Insulators respond to the potential difference and the atoms get distorted in the sense that some lose or gain electrons. Any imbalance in the atoms of a conductor equalizes when the current stops, not so with insulators. The fact that I can't see how a vacuum stores a charge doesn't alter the fact that it is the dielectric that stores the charge. Jim |
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Re: all my freinds
Lise Quinn
开云体育I
think what he is asking is more along the lines of preventing hacking -
understanding how hacking works so that one can safeguard their systems from
such things.
?
尝颈蝉é
" If you want to know where the apathy
is, you're probably sitting on it. "? Florynce R.
Kennedy
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Re: Fuses vs. resistors
Kevin Vannorsdel
I'm new to this group so missed the CMOS topic (which I would have
enjoyed)... CMOS transistors use metal as interconnects - mainly aluminum. The latest silicon processes are beginning to use Copper as interconnects. This is fairly widely publicized so you may all know this. The CMOS transistor itself is made of standard P and N type silicon (with various doping levels) along with Poly-Silicon for the gate and a bunch of silicon dioxide for the gate dielectric. Metal is still a very important issue in IC design. See my previous comments on electromigration... KV. ________________________________________________ Kevin Vannorsdel IBM Arm Electronics Development 408-256-6492 Tie 276-6492 kv@... KF6YCI Please respond to Electronics_101@... To: Electronics_101@... cc: Subject: Re: [Electronics_101] Re: Fuses vs. resistors heros, or that the length of a wire has nothing to do with resistenceSince these quotes are all mixed up and shortened I don't know who said what and for certain what he said. Here's my parting shot on the fuze, resistor, etc. topic. I was wrong when I originally said that a fuze has no resistance, and of course the resistance is required for it to fuze, i.e. blow, when it's rated current passes through it. That something has resistance doesn't make it a resistor. If it did we'd have to call everything that is not an insulator a resistors, transformers, wires, fuzes, etc. A resistor is not simply a device that has resistance but one in which resistance is utilized as part of the circuit design, to achieve a voltage drop when connected in series, to bypass current in a device when in parallel, i.e. shunt like the old D'Arsonval (SP?) analog meters when used to measure current. Someone earlier said that CMOS devices actually no longer use Metal, I don't know whether that is so, but we don't stop calling them CMOS, which may be why I didn't know that metal is no longer used in their manufacture. Anyway, that's my swan song on the issue. Jim To unsubscribe from this group, send an email to: Electronics_101-unsubscribe@... Your use of Yahoo! Groups is subject to |
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Re: all my freinds
Jim Purcell
Himanshu,
Who said that it [hacking] is a bad workJim |
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Re: all my freinds
Jim Purcell
ejazabidi,
i m very thankfull to all of u for reply to my message "hacking"I am far from an expert in computer security, however I will offer what I have learned. I used to say, no one will care to hack my computer, there's nothing there even interesting let alone valuable, and that is so. And if a hacker had to do his dirty work personally and individually on each computer I could breath easily, a hacker would derive no great feeling is accomplishment for hacking my computer and even less if he saw what was there. However, many hackers use something not unlike what used to be called a War Games program, from the movie by that name. Of course they probably don't bother dialing phone numbers, they probably generate IP addresses. Those are those funny four numbers separated by periods (dots). These are the actual addresses of computers on the internet. The site names are in a look up table which then converts them to the IP address. Now for most of us it is less important what the hackers do to get into a computer than how we can minimize the chances of their getting in. The first and as far as I know the most effective strategy is a fire wall. The term comes from real 'walls' that protect against real fire. For example, in an auto, the steel between the engine and the passenger compartment is called a fire wall. A computer fire wall can be software and hardware or both. At this point I use a program called 'Zone Alarm', which is free to home users. My copy is set up so that any I can go onto the internet without any problem, but anyone or anything on the net will be stopped by the fire wall. If some program tries to gain access to my computer via the internet I pop up windows asks if I want so and so to have access to my computer. Unfortunately the only information that is given is often just the numerical IP address mentioned above. Except in special situations I usually answer no. If I want the site to always have access to my computer I can check a box that says to remember my 'yes' or 'no' choice of this time. I hardly ever check this, I prefer a little inconvenience and more security. Another aspect of firewall protection is that when you install some software the companies may try to gather information about your computer and send it to the company. The only program(s) that I grant unlimited access to the internet are my browsers. Without it I can't get on the internet. What about hardware firewalls? Some people have more than one computer and don't want to have to switch their DSL or Cable modems between the machines. So they install a piece of hardware between their computers and their modem. (as far as I know these don't work with dial up.) This hardware provides a hardware firewall, and added to the software firewall provides reasonable security. Here are some common sense ideas about computer security. (remember, I am NOT an expert, these are only some things I have learned and are only worth a little more than no knowledge at all.) These rules as far as I know apply both to hacker intrusion and susceptibility to viruses. 1. No security system will make you immune to an expert hacker who really wants to get into your system, but most hackers are not experts, and they will go for the more vulnerable computers rather than waste time on those where the owner has taken steps to keep them out, rather like burglars. 2. Install a firewall, at least the free software type, like zone alarm, but a hardware type is good if you have sensitive information on your computer. If you have more than one computer and want them all on the internet, you need the network hub anyway. 3. Regarding viruses: a. Keep your anti virus software up to date, get all updates and often. b. Never accept attachments to email from people you don't know. Some even say not to accept them from people you do know if the person does not make reference in his message to the attachment. Viruses apparently can be attached to email while it is in transit. c. Be careful about software downloads. Most viruses must be executed or the programs they infect must be run. Email itself cannot cause a virus because it is data, the computer must treat a virus as a program. Attachments can be data but they can also be programs and if you run the attachment it could infect your system. d. Don't be afraid. Remember that only a small percentage of computers are hacked or get viruses. We pay attention to these things not necessarily because they are of epidemic proportions but because the results if you are hacked or get a virus may be harmful. Jim |
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Re: Fuses
Kevin Vannorsdel
Remember, power is dissipated ACROSS an element... the power that is
delivered to other circuits... the actual load power... is not really related (well, it is indirectly) to the power dissipated by the fuse. ________________________________________________ Kevin Vannorsdel IBM Arm Electronics Development 408-256-6492 Tie 276-6492 kv@... KF6YCI Please respond to Electronics_101@... To: Electronics_101@... cc: Subject: [Electronics_101] Re: Fuses Can anyone answer my original question - Why are fuses not rated inAs fuses are used as overcurrent protection devices, the relevant factor here is the CURRENT that the fuse will carry before melting. Power is somewhat irrelevant here, as it would be an indirect way to tell you the important parameter, the current capacity. I cannot recall anyone designing a circuit saying "then, I want the fuse to blow while it dissipates 10W or above", but " I want the the fuse to blow while 10A or above go through this path". Also, power alone is useless, you need also the resistance of the fuse to calculate the current capacity, or the voltage drop across the fuse. Guillermo. To unsubscribe from this group, send an email to: Electronics_101-unsubscribe@... Your use of Yahoo! Groups is subject to |
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Re: Fuses 60 volts???
Kevin Vannorsdel
???
Ever here of a fuse with 60 volts ACROSS it? Come on... power is the only thing that generates heat... this is either I^2 R or V^2 / R or I*E... you can't get any of these to equal something without a resistance... period. ________________________________________________ Kevin Vannorsdel IBM Arm Electronics Development 408-256-6492 Tie 276-6492 kv@... KF6YCI Please respond to Electronics_101@... To: Electronics_101@... cc: Subject: Re: [Electronics_101] Re: Fuses It is correct that fuses are in units of Current. Power(watts) is in units of (AMPS)Current and volts. POWER=VOLTS X CURRENT FUSES PROTECT CIRCUITS (IF SIZED CORRECTLY) WHEN THE Amps is sufficient to "blow" the fuses. If fuses were sized in Power (watts) they would have to be rated for a certain current, AND voltage and there are many combinations that one could come up with for a certain power rateing. ie. (power =60watts} could be a current of 1A at 60 Volts, or 60amps at 1 Volt, or 20Volts at 3 Amps. etc so it would not make sense to rate them using power (watts) From: "Guillermo Brajovic" <guillermo.brajovic@...> _________________________________________________________________ Get your FREE download of MSN Explorer at To unsubscribe from this group, send an email to: Electronics_101-unsubscribe@... Your use of Yahoo! Groups is subject to |
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Re: need help in Power Supply
Hi, its always good to make one but i'm concern about your safety, on
your case if you are experiencing a huge amount of surge you dont need to built one to replaced the other one the problem still there.I would suggest to get one reliable UPS uninterruptible Power supply this type of device has a voltage windows that can handle huge amount of surge and sag.If out of your budget mind to get on surge suppressor with circuit breaker.This i would like you to do if you really want to built one first monitor your ac utility during day and night time check how far the ac utility went beyond the nominal voltage 110Vac, check your ac outlet where the fax machine connected is it really properly grounded? if not have a elctrical technicain look on it, reason why I want you to check the proper grounding cause this in one reason why your psu on your fax keeps busted. during that time.let me know if you needs more info on voltage regulation.Electonics 101 advice Think first before you jump...just be careful.safety first. Thanks, The safet Guy - In Electronics_101@y..., reniar@c... wrote: we have a fax machine that is always busted whenever there's apower surge,so I suspected that the power supply of the fax machine isnot regulated..instead of fixing it I decided to make one. |
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(No subject)
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ET <FINE> ______________________________________________________________________ Abbonati a Yahoo! ADSL con Atlanet! Naviga su Internet ad alta velocit???, e senza limiti di tempo! Avrai sempre il telefono libero e non dovrai pagare il traffico telefonico per collegarti a Internet. Per saperne di pi??? vai alla pagina |
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Rockets and vacuum
Mark Kinsler
Talking about force, I wonder if a rocket could fly across a vacumn, which does not have anything at all. I just wonder how could force produce motion if there's no friction for it to force a motion.It could indeed, and they do so on a regular basis. A rocket's action should not be compared to that of tires on a road, where an icy road will prevent the vehicle from moving forward. Instead, the rocket moves because it throws gas molecules out of its exhaust nozzle. These molecules have significant mass. Thus when the rocket pushes against the gas in the process of expelling it, the rocket is also pushed forward. Put on a pair of roller skates, pick up a small, heavy object, and throw it. The air friction on the thrown object will be negligible, but you'll be propelled in the opposite direction nonetheless. As long as there's something to throw and a means of propelling it out of the nozzle, the rocket will continue to accelerate. Is outer space a vacumn?Yup. A much better vacuum than we can produce on earth, in fact. You don't have to go all that high to find it, either. A few thousand miles will do it, I think. Communication satellites operate in such conditions. M Kinsler _________________________________________________________________ Get your FREE download of MSN Explorer at |
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Re: all my freinds
开云体育Well said!? Do we really need to rant and rave
about the definition of a hacker?? Who cares?
?
?
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Re: Some very interesting links for you
开云体育The poltergeist story is quite something.?
Anybody have any idea if there exists a video of such controlled incidents
online somewhere?
?
Shaun.
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Re: all my freinds
Jim Thibeault (Tebo)
Go to and do a search about
toggle quoted message
Show quoted text
hacking, this site will tell you how just about anything works. Jim ejazabidi@... wrote:
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Re: Digest Number 134
Himanshu Sharma
开云体育Hey ,
?
As some-one has already suggested that charge is
stored on the plates and that the dielectrics is a medium for the charge
transfer...
?
Well may be the use of vaccum capacitors is because
of least dielectrics so that breakdown voltage is high... but this has a
trade-off that the capactiance would be low...
?
Regards :-),
?
--himanshu sharma
Correct me if I'm wrong, but didn't Ben Franklin, when he was doing his |
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Re: lcd display
Himanshu Sharma
开云体育Hi there ,
?
Well for that I don't think that you will get the
code in C but instead what you can do is contact any 8086 kit vendor and ask him
for the Assembly code..he will surely help you with all the interfacing
architectures...
?
hope that it helps...
?
Regards :-),
?
--himanshu sharma
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Re: lasers
Himanshu Sharma
开云体育Hi ,
?
Just to add to it...if you are talking about use of
lasers in lithography for the VLSI design or?may be some other piece of
info then better search the web using google...
?
PS:All ppl. have different attitude towards the
same question...
?
Regards :-),
?
--himanshu sharma
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Re: all my freinds
Himanshu Sharma
开云体育hey ,
?
>i just want to know "how it can happen" i don't want to do >it
my self
>i know its a very bad work. ?
Who said that it is a bad work...and by the way breaking into computers
is not the only hacking... we have phone-phreaking...even overclocking... and
many stuff like?that...so please mind what you say...and most importantly
it requires skill...
?
hope that it will clear as to what do you want..
?
Regards , :-)
?
--himanshu sharma
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