Hi Syed!

If you really want to learn about electronics from scratch and you
live in either U K or Europe you might consider looking at the Open
University Courses on electronics.

However I would advise you to get a good grounding in mathematics
first. Electronics is certainly a 'hands on' subject but trying to
do it without the maths background is rather like trying to knit
spaghetti, not to be recomended.

Even if you elect not to study with the Open University and and enrol
for one of the electronics courses at what you used to be called
Polytechnics you will still need to acquire mathematical skills. But
don't let that put you off. Once you start you will be amazed how
quickly it all comes to you.

Best wishes,

Anthony Qinn.

hi ,
i want to use LCD with a auronomous system.
waiting for ur reply.
sreeranga
--- Sergio_S?nchez_Moreno <ssm07@...> wrote:

Do you want to use the LCD in an automomous system
or with a PC?

----- Original Message -----
From: <sreerangap@...>
To: <Electronics_101@...>
Sent: Thursday, October 25, 2001 11:39 AM
Subject: [Electronics_101] lcd display

hello group
i am searching for a C source code for

initialising the lcd display.

of any make (not so particular). and getting it

started.

waiting for ur reply.
sreeranga



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Enter your vote today! A new poll has been created for the
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in ur opinion which field is
good.specially in paksitan and abroad.

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o electronics
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o electrical


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Thanks!

Hi Gusys,

Iam a new comer in electronic world...
Could somebody teach me what is differencies between
ASCII text and Modbus,for inter-device communication.
Is there an interface for these?

Thank's

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Dear Everybody,

My Name is Syed Rizwan Muhammad Rizvi, I'm from Pakistan love to
learn electronix but unfortunately I've no knowledge about but I'm a
good computer in many languages, please can any one of you help me
learn it all from the scratch.

Jim,

The software to program the PIC or the program itself?

Microchip has made available for free the development software that you
write your assembly program in - it's great, you can do all the good
debug/simulation stuff in it. It compiles to a common format hex file.

The programming software (you can use Microchip's, but it works almost
exclusively with their programming hardware) takes the hex file and writes
it to the chip's EEPROM (or EPROM).

The development software is free and programmers and programmer software can
be had for cheap or free.

PICs are great, because they give you computer control in a circuit with
just one chip...that doesn't require anything but a 5V source (some run on
less).

So many applications.

-Mike

d,

Start with the Microchip PIC16F84. It has EEPROM (flash memory) so you
don't need a UV lamp to erase it.

I'm trying to envision writing the software for this chip. I assume you need
some kind of development tool where the program is stored until it is running as
intended, this would have to include an interface with the chip so the program
can be dumped to it. As I said I have never used a PIC device. I couldn't
imagine anything that I might do with it that I couldn't write assembly for it.

Jim

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Jim,

The software to program the PIC or the program itself?

Microchip has made available for free the development software that you write your assembly program in - it's great, you can do all the good debug/simulation stuff in it. It compiles to a common format hex file.

The programming software (you can use Microchip's, but it works almost exclusively with their programming hardware) takes the hex file and writes it to the chip's EEPROM (or EPROM).

The development software is free and programmers and programmer software can be had for cheap or free.

PICs are great, because they give you computer control in a circuit with just one chip...that doesn't require anything but a 5V source (some run on less).

So many applications.

-Mike

d,

Start with the Microchip PIC16F84. It has EEPROM (flash memory) so you
don't need a UV lamp to erase it.

I'm trying to envision writing the software for this chip. I assume you need
some kind of development tool where the program is stored until it is running as
intended, this would have to include an interface with the chip so the program
can be dumped to it. As I said I have never used a PIC device. I couldn't
imagine anything that I might do with it that I couldn't write assembly for it.

Jim

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Hi my name is Mike and I am new to the list. I am a tinkerer and like
to build circuits for my hobby of model railroad. What information do
I need in order to design a transistor output from a 555 timer
output, to operate a bell that draws 1 amp at 6 volts dc. The
initiating voltage however is 12vdc for the 555 timer circuit.

Thanks Mike

Nothing is impossible, including this little project - I would suggest that
for the setup (of which you would know more about than I) you would need the
same number of automotive transformers (coils) as you have tubes -
triggering and switching is easy - a MOSFET should do the trick on each
coil.

The midi interface is slightly more complex - you will need a decoder of
sorts - MIDI is a type of isolated serial interface - so I would suggest
that an MPU is probably the go for that ... one of the PIC line of MPU's is
probably most appropriate, seeing as it has serial i/o onboard - as do the
now not-so-popular Motorola 68HC811 line of processors - you can use one
data line per tube or an addressed combination. The tricky bit would be (if
you have to develop it yourself) creating the program code to interpret the
interface commands.

The specs on the actual interface shouldn't be all that difficult to find,
so it may make your life a bit easier.

Hope this helps somewhat,


Regards,


Jonathan Luthje

Mounir,

I must agree with Jim! All the discussen about that
everything should be open source and that no one can own a
piece of code, is for me just plain bullshit! If you want
to make a piece of code available for everyone (like
Linux), then fine. Go for it. But what is the different
between spending time and money to, let's say, make a car
and writing a software code/music/movie ? Nothing. It's
still something you made and you have every right to earn
money on it!
The bottom line is that if creators of products or
documents or music receive no remuneration these important
things will disappear. We'll be back in the days when, if
you needed a hammar you made one.
Every try to buid your own car. Before the days of 'free
enterprise' (which is far from free) musicians depended on
a sponsor, usually someone rich. So only that which
pleased the sponsor got produced, or at least only
creators who had a sponsor had the free time to create.
They could of course do something else and create in their
spare time.

The fact is that efforts to protect creative products does
cause more inconvenience, even cost, to those who would
not steal the product by copying it. OTOH we don't know
how many people might pilfer products if they weren't
locked awy when unattended. We all know the phrase, 'that
lock is only to keep honest people honest.'
Yeah, companies might do what they can to maximaize
profits....but DUH!, that's the whole point.

Making a profit seems to be a cardinal sin for some,
mostly those who don't know how to make a profit. What
they forget is that part of their companies profit pays
their salary. How many would be willing to give up their
pay so the producet could be sold more cheaply.

What muddies the watters is that there definitly are
companies whose profit motive is so strong that that
motive as miles ahead of any other consideration, not the
welfare of their workers, not fairness to customers that
doesn't translate directly into profit. Why else do so
many companies have miniscule budgets to handle customre
service assistance and complaints. I suspect that radio
stations that play elevator music go out of business
because people get enough of it while waiting for a human
to talk to on the 800 number they called an hour ago.

Most of us wouldn't have jobs if the whole point for a
companie wasn't to earn money.

True, but most companies today seem to see fair treatment
of workers and of their customers far less important than
this months 'bottom line'. And that is I guess driven by
how well they do on the stock market. 'Long term' today
seems to have only one meaning, a school semester that
lasts 25 weeks instead of 16.
No, if a private person gets hold of an illegal copy of
Microsoft Office, then I would scream out loud, but
helping or participating in doing actual hardware changes
to a product so that it allows a person to make tons of
illegal copies is illegal and should be punished!

If only the pirating could be curtailed without
inconveniencing the customers. It is bad enough that so much
software is poorly written and so feature laden to hide the
defects that many people don't realize the problem. And if
they do, the company is making so much money from the rest
that they don't care about the 'wieners'.

Jim

I understand that it's a bit startling to think of a fuse as a resistor. I realized that they were the same sort of thing when I was teaching a class one evening and found that there wasn't any other way to explain their operation.

My mention of a 'heat sinked' fuse wire was meant to emphasize that if the wire inside a fuse somehow stays cool, it won't blow.

Fuses aren't rated in power because the load on a fuse varies with the circuit voltage. If you're an electrician in North America and only deal in 120v circuits, then indeed fuses could be rated in watts. A 15 ampere fuse would blow if the power dissipated in the circuit was greater than 15 amperes x 120 volts = 1800 watts. But the very same fuse could be used in a lower voltage circuit: a 15 ampere fuse could be used in a 12v circuit, in which case it would blow if the load dissipated power in excess of 180 watts.

To confuse matters further, power doesn't melt the fuse wire: energy does. Energy = power x time. If the time is very short, then the energy is very small. This means that a very high current that persists for only a brief period will not blow the fuse. Fuse manufacturers provide a 'time-current' plot to let engineers how long it takes the fuse to stop the current for a particular value of overcurrent. When equipment is being designed, the engineer has to figure out how much overcurrent the equipment can handle, and for how long. Then he uses the time-current graph to select a fuse that will blow before the equipment is damaged.

This 'time-current' business is pretty startling in one application. Laboratories that produce artificial lightning use thin (#24, bare, tinned) wire to carry the lightning currents. The currents are very high--in the thousands of amperes (ever hear of a kiloampere?) But the duration of lightning currents is around 100 microseconds. Power x time = energy is thus very small, and these utterly inadequate-looking wires work just fine.

A good example of a truly strange fuse is the old VW fuse. Had a ceramic body with the fuse wire on the outside. Sprayed molten metal on the rest of the fuses, sustained damage from the dust and crud in the car, and generally was horrible. Nobody ever explained why they were made this way, though it's possible that the fuse wires were replaceable. Industrial fuses are often made with replaceable wires.

The unknowns vs. equations business I mentioned in my earlier post was something that you'll run into in some first-year electronics courses.
You're given a roll of fuse wire whose resistance is r/x ohms per meter, and which will melt when its temperature reaches 200 degrees C. You're asked to come up with a fuse that will blow when its current reaches 10 amperes. You have to know the heating characteristics of the wire to solve the problem. Generally it's easier to just experiment.

M Kinsler

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You answered your own question. Fuses are current sensitive. If rate in
power, say like 200 watts, 200 amps at 1 volt is 200 watts same as 10 amps
at 20 volts.
Jim

Message: 13
Date: Fri, 26 Oct 2001 14:38:01 -0700
From: PDJ <phil@...>
Subject: Fuses

Hello,

Great discussion on fuses. Mark was correct in describing how a fuse
works but failed to answer the question "Why are fuses not rated in
units of power".

Ampere rating. Select the ampere rating for the fuse so that the fuse
can carry the normal operating-current conditions of the application.
The recommended operating current for the fuse is 75% of the nominal
rating. The derating of 25% compensates for the differences between the
documented UL-rating test procedure and the typical application.

Can anyone answer my original question - Why are fuses not rated in
units of power?

Thanks,
Phil

or that the length of a wire has nothing to do with resistence
- mark

--- In Electronics_101@y..., "G Ramasubramani" <grama@a...> wrote:

I didn't mean for this to turn into a pissing contest, I do tend

to like to get things stated correctly, a trait the burned my dad to
the anger point.

But I do find it surprising that one who likes to get things stated

correctly does not want a wire to be called a resistor!!

开云体育

Fuse and resistors are precisely the same thing, Without going into details,
both will "blow" if their current ratings are exceeded.



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Mounir,

However, if you have the phototransistor turning on/off a relay. And you have a piezo on the other side of the realy, the this resitance shoulder matter. Cause the relay can only be on or off, nothing in between.

Yes, but it the photo transistor is not conducting enough to operate the relay or it's on the raged edge of conduction it might not work as well as it should. I would try dumping the relay and putting the alarm device in series with the collector and Vcc.

Jim

guillermo,

>I have never seen a heat sinked fuse.

I clearly read that Mark didn't mean a heatsinked fuse, but a common fuse IN CONTACT with a heatsink (let's say, for example, the secondary fuses of a power supply's tranny in contact with the rectifiers heatsink).

Unless you meant it was in contact accidentally it would still be a heat sinked fuze, as in the fuze heat was intentionally heat sinked or it was used as a heat detector or something (reference to a tranny in contact with a fuze)

Jim

P.S. your name if I don't miss my guess is the same as Marconi's, I have always wondered how that name was pronounced.? I'm guessing that phonetically it would be spelled, 'gee-er-mo' but that's how I would guess the Spanish pronunciation might be. I know even less Italian than Spanish. :-)

Jim

Interesting story! I'd like to have a shot at teaching high school kids
someday.

I think you are thinking of "magneto-striction"- this is the phenomena
that causes transformers to hum, wires to vibrate etc... it is the
movement (vibration) of metal due to current flow (if memory serves
correctly). It is an important element of the design of the Magneto
Resistive head used in todays hard disk drives (and other storage
devices).

Electromigration is actually movement of metal from "here" to "there". It
can cause a wire to actually get thinner on one side and fatter on the
other. I don't know the actual physics behind it... I assume it has
something to do with what happens to the metal atoms when a ton of
electrons get moved through them.
It is a very real phenomena though in IC design.


Have you ever heard of Ivor Catt? He has a very bizarre notion about
current flow and charge in capacitors etc... I started to read his stuff
but became afraid that it would "mess me up".

Have a great night.


________________________________________________
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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




Kevin,

Fuses have resistance, that is true.

Yes and I realized that I had misspoken right away. That's what comes when
you
spend seventeen year trying to teach students who don't the difference
between
a pot and a grid leak. (I had to say it that way, I read that once back
in
the vacuum tube days.) Anyway, I could tell my students transistors were
made
of bird doo doo and some of them would have believed me. In that situation
one
doesn't get tested, nor does one's thinking get challenged very often. I
recall being surprised when my fellow teacher said the the charge on a
capacitor is stored in the dielectric, not on the plates. And of course
it's
true, what I can't figure out is where it's stored in vacuum capacitors.
They
are used in high voltage circuits, in radio transmitters we sometimes have
problems with humidity causing caps. to arc.

I got my pride back when I explained that AM radio stations can modulate
above
+/- 5 kHz. He thought that the 10 kHz spacing that they were so limited.
But
stations are not assigned adjacent channels where they'd be close enough
to
interfere.

Have you guys ever heard of electro-migration? This is the movement of
metal due to current flow.

Is that when wires carrying high current sometimes vibrate?

It is a serious consideration in IC design. It is an interesting

concept...

but I think heat is the mechanism of fuse blowing anyway.

True but it makes sense that the fuze would have to have resistance since
with
none there'd be no heat and thus the fuze would not fuze. :-)

Jim



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