Chip with simple program for Toy

[Michael Black]

Rich Grise (richgrise@example.net) writes:

On Mon, 18 Apr 2005 07:24:31 -0700, Thomas Vogel wrote:

hi,

I can´t find this group: "alt.binaries.schematics.electronic ".

Can anybody give me a link for this group?

No. There is no such thing.

To access alt.binaries groups, you have to have a real newsreader,
connected to a real newsserver. Google wants to protect you from
naked pictures.

Actually, google doesn't want to waste the space on binary newsgroups.

After all, they are an archive and any space used is forever (or until
they go broke, which of course is what happened with dejanews before it).
Hundreds of text messages can fit into the space of a binary post.
And of course, much of those binary messages are illegal copies of sofware,
movies, tv shows and music.

Michael

 

[Lord Garth]

"John Fields" <jfields@austininstruments.com> wrote in message
news:qr9861tu7scthds7tu5mqrnl85l8mn2u26@4ax.com...

You can do it like this:

Connect the keypad row lines to the UM95089 row inputs.
Connect each of the keypad column lines to the base of
an NPN switch (such as 2N3904), and ground each emitter.
Connect each collector to one of the UM95089 column inputs.
This circuit is shown for a 2x2 switch array below, where
R1 and R2 are row inputs and C1 and C2 are column inputs.

.-----------o----------- R1
| |
| |
o | o
|=|> |=|
| o | o
| |
'---. '---.
| |
.---)-------o---)------- R2
| | | |
| | | |
| o | | o |
|=|> | |=|> |
| o | | o |
| | | |
'---o '---o
| |
| |
| |
--- ---
.-v \-. .-v \--.
| | | |
GND------o-----)-----' |
| '--- C2
|
|
'---------------- C1
(created by AACircuit v1.28.4 beta 13/12/04 www.tech-chat.de)

This circuit gives up a little noise margin, but as long
as it is operated at room temperature or above and
the keypad is close to the IC, this degradation should
not cause a problem.


---
Very nice.

The datasheet specified Vil as .2 volts max. I'd give it a shot though.
Jack// ani, let us know how it does. If you don't get the row tones, you
need to consider John's circuit.

You'd have no problem if you had a MK5087 or MK5092 tone dialer, these
use a 2 of 8 keypad. Would you want me to look for one?

 

[Lord Garth]

"phaeton" <blahbleh666@hotmail.com> wrote in message
news:1113857044.747933.34890@g14g2000cwa.googlegroups.com...

I don't think it is possible to hear the resonance of the body
through
all that distorsion, but I can be wrong.

Actually I was referring to the acoustic sound of the guitar being
picked up by the mic directly. While recording, the amp was at my
feet and i was sitting down, and if you listen closely you can hear the
pick and strings snapping.

Strange actually. Maybe there is some non-intended noise gate
function
in the circuit.

yeah, that's exactly what it acts like- an overzealous noise-gate with
a high threshold. I would have just said "noise gate" but i didn't
know if you were a player and/or would know what i meant

There are many versions of the TS

In this case it is a TS-15....a mid-90's era "Soundtank"- style. Not
the best example of a TS, i know. I've never looked at the schem for
this one, but i'll assume you are right- it's got a "bounceless" type
of switch, which could very well be a momentary switch and some FET,
and is definately not a true bypass type.

(I've also got a TS-10 with the classic "Jack separating from the PCB"
syndrome, and i intend on cloning a TS-9 and/or TS-808 later this
summer. I promise not to bug you guys about those )

I think the sound is very different when the TS is connected, so
there
is distorsion from that too, but a good kind of distorsion I would
say.

I like the distorted tones overall. I still have yet to look at your
links, and try (all) your suggestions, but I will (long story short,
i have limited time at home to actually play with things)

Perhaps i should have done this first anyways- built one up (even if a
duplicate) on breadboard and just experimented on it. I'd like to do
this anyways.

Thanks to y'all for all the suggestions and tips!

-phaeton

Have you tried the variable gain pot rather than the switch?

 

[Lord Garth]

<stu@aaronj.com> wrote in message
news:1113854206.490546.164360@g14g2000cwa.googlegroups.com...

http://www.motherearthnews.com/search/

from an 1979 article

With the price of gasoline already out of sight, just about everyone is
scrambling for a way to squeeze the last possible drop of energy from
each precious gallon. However, David Arthurs-of Springdale, Arkan
sas-probably couldn't care less ... because he has designed and built a
car that can travel 75 miles or more on just four quarts of the
expensive liquid!
snip


BoyntonStu

Well, motors for A/C, power steering and hydraulic brakes come to mind
rather rapidly.

5 horsepower is 3730 watts at the gasoline engine, 48 volts x100 Amps= 4800
Watts demanded by
the generator. Assuming the 3730 Watts are delivered to the generator,
3730W/48V= 77.71 Amps
at best from the generator. Not all can go toward propulsion.

How efficient is a jet engine starter motor? Aren't these usually mounted
on a truck? What sort of
generator runs the starter when used in its intended role? Such a motor
isn't designed for continuous
duty.

This sound like a fanciful tale.

 

[John G]

"Lord Garth" <LGarth@Tantalus.net> wrote in message
news:RCF8e.191$yd7.49@newssvr11.news.prodigy.com...

"js5895" <JoshTmp@nycap.rr.com> wrote in message
news:1113790587.746117.184540@o13g2000cwo.googlegroups.com...
I have the meter in voltage reading mode, not current mode, ouch!,
lol.
I was testing it the night I got it, and forgot the load, and it was
lights out. When I have it in voltage mode it's in a complete
circuit.
I had it in current mode, line to each screw on the switch but,
making sure it's wasn't a complete circuit, that's when it dimly lit,
which was weird, since it wasn't a complete circuit, but it only did
this once, I tried it again and nothing happened, it could of been
some anomaly from the no load incident or, because it's new.
I updated the image to show the common point, and where the switch
is sending power, here:
http://home.nycap.rr.com/joshs/threewaywire.bmp

Thanks.


Hey thanks, that little arrow help a bunch. No, I can't tell you why
it
lit the neon at all, I'll just have to waste one! Have Dremel, will
travel.
Remember that voltage is read across a circuit or device, not in
series.
Please don't read current when your testing mains unless you get a
clamp
on probe. I'm glad you and the meter are okay!

There are neon testers around which have a neon and resister inside a
screwdriver handle and a metal contact at the end of the handle.
If the blade is on a hot wire then the neon will light if you put your
finger on the other end.
The circuit is completed by the capacitive coupling of your body to the
general ground which of course is at the same potential as the neutral.
--
John G

Wot's Your Real Problem?

 

[Lord Garth]

<stu@aaronj.com> wrote in message
news:1113880251.207571.266120@f14g2000cwb.googlegroups.com...

I suggest that you read the article. It is about 25 years old. I
believe that over 15,000 sets of plans have been sold. There was also
a follow up article a few years later.

My only point in this forum is that a mechanical PWM can soft start a
DC motor.

If you think about a brushed DC motor, there is no reason to doubt that
a brushed 'controller' could handle any current the motor required. It
might even be possible to vary the duty cycle for different speed.

I don't doubt that plans have been sold, more power to the guy for his
marketing prose. I just think the figures need to be revisited. Today,
a solid state PWM would be the speed control choice.

What is needed is an up-to-date rebuild and perhaps a chart plotting the
acceleration. For highway, we need 60 in town and 70 on the intercity
runs & 75 on a few tollways with headroom to accelerate, admittedly a
tall order. Range should not be less than 350 miles though more is nice.

 

[Don Kelly]

<liaaba@yahoo.com> wrote in message
news:1113855304.329658.216800@z14g2000cwz.googlegroups.com...

Larry Brasfield wrote:
liaaba@yahoo.com> wrote in message
news:1113853100.364776.71430@g14g2000cwa.googlegroups.com...
Larry Brasfield wrote:
"Susan" <liaaba@yahoo.com> wrote in message
news:1a0b6eef.0504180838.601ae044@posting.google.com...
Hi,
Hi, Susan or Keith.


I'm using my girlfriend's account, so this is Keith, not Susuan.

Hi, Keith.

I was having this conversation with my friends the other day, he
saw
some guy on TV, he was touching some power source with 1 hand,
and
holding a fish on the other, and his feet were standing on
ground
(i.e. he's connected to ground). When they start the power
source,
the fish starts frying and he was OK (now this is not the part
we're
arguing about). So we started arguing, I was saying, since he's
connected to ground through his feet, there should be minimal
(if not
none) current flow through his other hand that's holding the
fish,
since it's an open node, there is not return path, so there
should be
no current flow to that arm

That's right. Such a demonstration would
have to be a hoax.

(i.e. I'm viewing the human body as a 5
way circuit, 4 limbs, and your head all connected together to a
common
node, your body, so 1 hand and the 2 legs form the complete path
for
current flow, and there should only be current flow in this
path, as
the other branches are not connected to a return path for the
electrons to flow, now I know I'm making a lot of assumptions
about
the human body, and I'm assuming limbs work the same way as a
copper
wire, in that electrons can only flow 1 direction in it in any 1
time),

That model is good enough for the present purpose.


So does this mean that under normal (real) circumstances, the
person
will get electrocuted and the fish will remain untouched?

If the power source had enough voltage relative to earth,
and the victim had conductive enough shoes and stood on
conductive earth, then I would expect the victim to get a
very bad electrical shock. And if it killed him, he could
be said to have been electrocuted.

If so, does
that mean whenever a person gets electrocuted, whichever body parts
are
not connected to the ground or not part of the path to ground, they
will remain unelectrocuted?

Electrocution applies to the whole organism. (It
either lives or dies.) But current sufficient to cook
flesh or disrupt heart or nervous system activity, at
line frequencies, pretty much has to flow through
ohmically connected circuits. So the person in the
hoax was not prone to having his fish-holding arm
shocked.

hence I was arguing the fish should not be fried, there should
be a charge build up on the fish, but since the fish is not
connected
to a return path, there should be no current through it. This
made
sense to me, but my friend did mention something that got me
pondering
as well, as we see on TV (urban legend or not, I don't know),
when
people get electrocuted, their hair is all buffed up,

That is a requirement of Hollywood physics, not
the physics that govern in the real world. Also,
any electrical phenomenon must involve visible arcs
curling all over the place in Hollywood physics.

meaning there
was current flow into their head (possibly via the veins? bloody
is
liquid, so it's conductive right?), but then, this would throw
my
theory off, hence, I'm here to look for an answer.

Stick with the physics you learned in school or
textbooks and pay no attention to TV or movies.

Taking this further, so suppose someone grabs onto a floating
power
source (say a broken transmission line), as long as his feet (or
any
body part) are off the ground, he won't be electrocuted (much
like the
bird on a transmission line...not yet anyway, but as soon as he
steps
back onto ground, it'll get really interesting...speaking of
which,
how do the birds discharge themselves without getting
electrocuted?),
is this correct?

Roughly true. However, at high enough voltage,
(which is lower as frequency increases), enough
current can flow capacitively to be dangerous.
The best rule is: Stay away from high voltage lines.


So how does the bird discharge themselves after leaving the
transmission to avoid getting electrocuted? Or do they?

Birds that live when landing on power lines do not
complete a circuit. Their feet are shunted by a fat
piece of copper so little voltage appears between
their feet. And little current flows through their legs.
What little capacitively conducted charge they may
have, if they depart the line not at a voltage zero
crossing, is small compared to the what you have
likely experienced when you shuffle across a nylon
carpet in your rubber shoes and touch a grounded
object.


Finaly question, I heard of this exploding squirrel story, about a
squirrel running on a transmission line, accumulating charges along the
way and when it stepped off the transmission line (to something that
was grounded, ie, a wall or something), it exploded because of
electrical shock and it brought down an the transmissione line. Now I
don't know if that was just another urban legend, but if it was indeed
true, how could the squirrel avoid such an explosion?
----------

If this happened it is because the squirrel either made contact with
something grounded or got close enough that there was a flashover. It
happens. The squirrel causes a fault and arcing which could cause the line
to be tripped out (it wouldn't physically fall)
Whether the squirrel was stationary or running along the wire, the charge
it has would be the same- negligable.
Note that routine maintenance on EHV lines is often done live. The worker is
in an insulated bucket and wears a conductive suit which is connected to the
live line. This ensures that his whole body is at the same potential as he
is big enough to distort the local field and have very uncomfortable voltage
differences between parts of his body if such a suit was not used. Sure,
even with the suit, he is a charged body but that is pretty insignificant.

--
Don Kelly
dhky@peeshaw.ca
remove the urine to answer

 

[Larry Brasfield]

"Lord Garth" <LGarth@Tantalus.net> wrote in message
news:BiY8e.352$l45.141@newssvr12.news.prodigy.com...

"John Fields" <jfields@austininstruments.com> wrote in message
news:qr9861tu7scthds7tu5mqrnl85l8mn2u26@4ax.com...
You can do it like this:

Connect the keypad row lines to the UM95089 row inputs.
Connect each of the keypad column lines to the base of
an NPN switch (such as 2N3904), and ground each emitter.
Connect each collector to one of the UM95089 column inputs.
....
This circuit gives up a little noise margin, but as long
as it is operated at room temperature or above and
the keypad is close to the IC, this degradation should
not cause a problem.

Very nice.
Thanks, John.

The datasheet specified Vil as .2 volts max. I'd give it a shot though.

The datasheet specifies Vil as .2 VDD, meaning VDD/5. This is
comfortably above the 0.65V to be expected at a biased base
as long as VDD is 5V.

....
--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Lord Garth]

"Larry Brasfield" <donotspam_larry_brasfield@hotmail.com> wrote in message
news:U_09e.85$Y55.9471@news.uswest.net...

"Lord Garth" <LGarth@Tantalus.net> wrote in message
news:BiY8e.352$l45.141@newssvr12.news.prodigy.com...
"John Fields" <jfields@austininstruments.com> wrote in message
news:qr9861tu7scthds7tu5mqrnl85l8mn2u26@4ax.com...
You can do it like this:

Connect the keypad row lines to the UM95089 row inputs.
Connect each of the keypad column lines to the base of
an NPN switch (such as 2N3904), and ground each emitter.
Connect each collector to one of the UM95089 column inputs.
...
This circuit gives up a little noise margin, but as long
as it is operated at room temperature or above and
the keypad is close to the IC, this degradation should
not cause a problem.

Very nice.
Thanks, John.

The datasheet specified Vil as .2 volts max. I'd give it a shot though.

The datasheet specifies Vil as .2 VDD, meaning VDD/5. This is
comfortably above the 0.65V to be expected at a biased base
as long as VDD is 5V.

I guess I misinterpreted that Larry. Are you saying Vil is .2*5 or 1 volt
or less
for a 5 volt supply to be a logical low? 20% of Vdd. That would be easy to
reach.

Thanks.

 

[Larry Brasfield]

"Lord Garth" <LGarth@Tantalus.net> wrote in message
news:mV29e.469$yd7.267@newssvr11.news.prodigy.com...

"Larry Brasfield" <donotspam_larry_brasfield@hotmail.com> wrote in message
news:U_09e.85$Y55.9471@news.uswest.net...
....
The datasheet specifies Vil as .2 VDD, meaning VDD/5. This is
comfortably above the 0.65V to be expected at a biased base
as long as VDD is 5V.

I guess I misinterpreted that Larry. Are you saying Vil is .2*5 or
1 volt or less for a 5 volt supply to be a logical low? 20% of Vdd.
That would be easy to reach.

They give the value as 0.2 and the units as VDD. This is unusual,
so I relied on the Vih spec, which ranges from 0.8 VDD to 1 VDD,
to help make sense of that Vil spec. Also, a MOSFET threshold
as low as 0.2V would be most unusual.

Thanks.

Welcome.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Lord Garth]

<stu@aaronj.com> wrote in message
news:1113910028.049477.77300@o13g2000cwo.googlegroups.com...

"Today, a solid state PWM would be the speed control choice."

I totally agree.

Here's a thought provoking problem:

You are in a "Junkyard Wars" episode and need to control a 500 Amp 48
VDC motor. You are given a $30 and free rein of the junkyard. What
would you do to solve this problem?

BoyntonStu

Umm, build a wafer fab?

I guess that's why I find shows like this fascinating!

 

[Rich Grise]

On Tue, 19 Apr 2005 04:27:08 -0700, stu wrote:

"Today, a solid state PWM would be the speed control choice."

I totally agree.

Here's a thought provoking problem:

You are in a "Junkyard Wars" episode and need to control a 500 Amp 48
VDC motor. You are given a $30 and free rein of the junkyard. What
would you do to solve this problem?

A lot will depend on what "kind" of junk. Military surplus avionics,
or scrap cars? Or something in between, or broader-spectrum? Lawn
furniture? The kitchen sink?

Cheers!
Rich

 

[Lord Garth]

"Boki" <bokiteam@ms21.hinet.net> wrote in message
news:d43bmp$66n$1@netnews.hinet.net...

Hi All,
Simple questions.

What is Chip Enable ? ( a PIO of flash memory )

All other PIO will only funtion correct until Chip Enable is high?

Best regards,
Boki.

When CE is false (low), the outputs and inputs are in tri-state or high
impedance, it is as if
the chip were not there. In fact the chip goes into a low power state for
minimum
drain on the supply. Micro amps of drain is common in this mode.

CE must be true (high) for the device to operate.

OE or Output Enable allows for the address bus (and select logic) to access
the device without
causing data to appear on the data bus. Think of an EEPROM which is being
written, you
would not want the data, which is being changed, to be available until the
write operation
is finished.

 

[Larry Brasfield]

"js5895" <JoshTmp@nycap.rr.com> wrote in message
news:1113944855.027225.197260@f14g2000cwb.googlegroups.com...

Hi,
Hi.

I posted earlier about how a 3-way, illuminated switch works, well, I
hooked it up permanently.
One is the new commercial grade illuminated 3-way switch and the other
is an old residential
grade non-illuminated 3-way switch. I came in the house and saw that
the illuminated switch
was lit and the load was off so, I went in the house and flipped the
non-illuminated switch and all
I could hear was arcing and the load not lighting up so, I flipped it
off and it stopped, I tried it
again and the same thing happened, I tried a third time and the light
started flickering and then fully lit
up, then the arcing sound stopped, I tried 15 more times and it worked
fine, I smelled the
switch and it smells of ozone. The non-illuminated switch was lying
around in my tool box for
4 to 6 years and it had light oxidation on the terminals but, it came
from the inside, I thought maybe it was because the
load was a small fluorescent sconce but, I think it's because the up
position of the switch
probably had oxidation on the part that the actuator connected to,
because switched
down it was fine, it only did that in the up position. I think to ease
my mind, I'm going to buy
a new one, a commercial grade one, just for added security, but what do
you people think about this?

Residential switches have a pretty good safety record, but
your experience shows part of why building codes require
them to be put in a box. I would just buy a modern switch
designed for residential use and not worry about it.

BTW, the fluorescent lamp load is one of the more brutal
with respect to causing arcing in a switch. Yours probably
had some dirt in it, or even a bug.

Thanks for all your help.
Anytime.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[John Fields]

On 19 Apr 2005 11:03:51 -0700, Tommi-Vogel@gmx.de (Thomas Vogel)
wrote:

Hi,

no, it´s not for a bomb! I just need it for my music station to woke up in
the morning. My new music station has no timer and I can´t switch it with a
timer. So I want to construct a circuit, which switch by an alarm clock over
a relay a remote control. Pleas email me the schematic+parts list.

---
Here ya go:


+---+---------------+------+------+---+---+-------+
| | | | | | | |
| [10k] [1M] [100K] [10K] | |K | O------>C
| | | | | |[1N4148] [COIL]- -|
| | +-|+\ | | | | | O--> |
| | | | >-+------|-|+\ | | |
[BAT] +-[0.1ľF]-+-----|-|-/ | | | >--+-------+ +----------->NO
| | | | | +-|-/
| | | | |+ | |
| [MIC] [100k] [10K] [10ľF] [1M] |
| | | | | | |
+---+---------+-----+------+------+---+


The microphone is a Panasonic WM-61A, the comparators are part of an
LMV393, the battery is 3X 1.5VAA, and the relay is a COTO 9007-05-40.

Here's how it works:

After you finish building and testing it, put it in a soundproof box
with your alarm clock and connect the relay contacs (C and NO, above)
to the remote control. Voila!, when the alarm clock goes off you
won't hear it, bit it'll turn on your music station. (Radio???)

Or, you could forget the whole thing and just let the alarm clock wake
you up.

--
John Fields
Professional Circuit Designer

 

[Rich Grise]

On Wed, 20 Apr 2005 07:38:59 -0700, Jason wrote:

Please forgive the pure ignorance of this question. I understand that
this is very basic stuff that I should probably know, but I have never
been to class to learn about this stuff, nor have I found any tutorials
that explain this stuff in simple everyday terms. I passed by
technician and general class amateur license exam by memorizing the
right buzzwords for this stuff, but not actually understanding the
concepts. I admit, I am ashamed of this fact. Here's what I have
gathered so far.

1. DC current flows through a crystal.

No.

2. The resonance of the crystal causes the current to form waves around
the frequency of crystal

No.

3. This new "pulsating" current is then amplified and then sent through
the crystal again. (This is called positive feedback)

More or Less.

4. The pulsating current is sent through a low-pass filter to "filter
out" unwanted frequencies. (That's why I said "around the frequency"
of the crystal)

Not Exactly.

5. From the filter, the current flows to an antenna which converts the
current to RF radiation.

In a way, yes.

Comments and help would be greatly appreciated.

http://www.electronics-tutorials.com/basics/basic-electronics.htm

Have Fun!
Rich

 

[Andrew Holme]

phaeton wrote:

As a kid growing up in the 1980s i took apart everything i owned or
get my hands on to see what was in it. Toy trucks, R/C cars, tape
decks, computers, game consoles, bicycles, typewriters, my mom's
sewing machine, the lawnmower, etc...

Most of the electronic stuff i took apart in the 1980s and early 1990s
had a lot of "through-hole" style (for lack of better description)
components soldered down onto a (usually) single or double-sided PCB.
Resistors, Diodes, Caps, Transistors and stuff just like we've all got
in our lil plastic trays, with the long leads that you stick through
the hole and solder.

Nowadays (i spend a great portion of the day working on computers)
most electronics stuff i see is mostly miniature surface mount
components, which from a manufacturing standpoint makes lots of sense
for a lot of reasons. There are exceptions, i.e.. caps, crystals,
chokes (where size is a factor in its specification or performance)
and high-power transistors or voltage regulators (large to dissipate
heat).

Is there plenty of through-hole stuff still being used in
manufacturing these days, or with manufacturing shifted towards SMD,
will through-hole resistors, transistors, diodes and such start to
grandually become less available and more expensive over the next
several years? I can think of some places where through-hole stuff is
a better option, i.e. protoyping or higher powered stuff. Looking at
the catalog at National, there's no shortage of through-hole stuff in
current production at the moment. I'm sure it'd be a long, slow
process (like decades) to phase out through-hole components completely
and use up all the stock/surplus.

I've spoken with a hobbyist on IRC that claims to build most of his
projects with SMD components- he arranges them on his PCB, applies
solder paste appropriately and sticks it in a toaster oven. He could
be full of crap, i've never seen pics, but i can't think of any reason
why he'd lie about it. He's knowledgeable, helpful, and
well-respected, and doesn't smack of someone just trying to be l33t.
Surface-mount is actually his preference, but to me it seems like that
approach would be more hassle and less fun (disclaimer: i've never
done it that way). Through-hole stuff just seems like it would be so
much easier to work with.

Thoughts?

I've started hoarding through-hole components for fear of limited supply.

Try Googling for "toaster oven" and SMD

e.g. http://www.seattlerobotics.org/encoder/200006/oven_art.htm

Everybody's doing it, it would seem.

 

[Michael Black]

"Jason" (theologygeek@gmail.com) writes:

Please forgive the pure ignorance of this question. I understand that
this is very basic stuff that I should probably know, but I have never
been to class to learn about this stuff, nor have I found any tutorials
that explain this stuff in simple everyday terms. I passed by
technician and general class amateur license exam by memorizing the
right buzzwords for this stuff, but not actually understanding the
concepts. I admit, I am ashamed of this fact. Here's what I have
gathered so far.

1. DC current flows through a crystal.
No. A crystal is made of quartz, which isn't a conductor. It will

never pass DC. Electrically, a crystal is the equivalent of an inductor
and capacitor in series, hence it's ability to control frequency.

Really, you need to get a book about radio and start reading. There
is a big difference between asking questions based on points you
don't understand, and asking us to write that material down here.

You don't have the basics to understand how it works, and you
have made too many leaps in your questions.

Here's one place to start. Take an amplifier of some sort (even
a computer with speakers connected to a soundcard), and plug
in a microphone. Hold the microphone near the speakers, and
start turning up the volume. You'll start getting a squeal,
that's the positive feedback, ie oscillation.

The signal goes through the amplifier and then is fed back to
the input, not just once but an infinite amount. It's no longer
amplifying an external signal, it is oscillating.

The frequency of the howl is determined by the inherent characteristics
of the setup, things like the response of the microphone and the speaker,
and the response of the amplifier, and even the microphone's distance
from the speaker. You don't have much control over the frequency, but
it is a good demonstration of oscillation.

Usually, one wants something more definite. So instead of the
speaker/microphone combination, the output of the amplifier feeds
the input directly. And between the output and the input is
some selective element so the feedback is at that frequency. Put
a bandpass filter in there that has a center frequency of1KHz,
and the thing will oscillate at 1KHz.

The crystal acts as the selective element, to ensure that the
oscillator runs at that frequency.

A crystal is one of the better filtering devices available, it
doesn't generate unwanted signals.

But the active elements are not so perfect, and they will often
add unwanted signals. Indeed, the design of some transmitters
will count on generating multiple signals, with the wanted
one filtered out.

Michael

2. The resonance of the crystal causes the current to form waves around
the frequency of crystal
3. This new "pulsating" current is then amplified and then sent through
the crystal again. (This is called positive feedback)
4. The pulsating current is sent through a low-pass filter to "filter
out" unwanted frequencies. (That's why I said "around the frequency"
of the crystal)
5. From the filter, the current flows to an antenna which converts the
current to RF radiation.

Comments and help would be greatly appreciated.

 

[Larry Brasfield]

"Richard" <REMOVE AT-DOTrwskinnerAT@awesomenetDOTnet>
wrote in message news:4266d96f$1_2@127.0.0.1...

I posted about a SBC P4 that randomly failed to boot (Power up) and want some ideas how to get accurate current measurements. You
kind folks helped out by explaining the Shunt deal.

Since then I have taken numerous measurements and I want to share my setup in case someone has so ideas.

First, the spec of the SBC is Max. 4.5 amps on Start up, Normal 3.2 amps.
I am using a 5 vdc DC COnverter located 14" away using 18 ga Instrument wire 14" long to carry the power. I "thought" is was
large enough, but now I have second thoughts.

When I first power up the DC Converter, I see a small spike which is right at 10 amps, and it only last for a few ms. Then the
power drops to about 1.5 amps. When the computer beeps, I jump up to 3.5 amps then to 7.5 amps, then immediately back to 3.5,
then it slowly settles down to around 2 amps. Now I only have 10% Processor Utilization at any given time.

I suspect your current spike corresponds to some
extra activity. Is the internal clock speed varying,
as uP's intended for mobile use often do?

I take it, the 10 amp jump is the initial in rush current?

Yes. You are charging the bulk bypass caps with it.

then the 7.5 amps is a very breif spike from the SBC kinking off?

Hard to say (even if I wished to guess what "kinking off"
is, but I don't want to know ;-).

Does this mean my 18 ga is border line and I would really need 16 ga for the power distribution wires? I did note that with the
18 ga wire there is 90 millivolt drop from the DC Converter terminals to the SBC Power Terminals so I think that is a good
indication I need to step up a size.

That's a little much for a 14 inch wire run. At those
currents, heating is not really an issue, but drop may
be depending on your supply tolerance and how the
SBC is specified. 16 guage should be plenty big.

Any thoughts,

Is there a reason to go for the smaller wire?

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Jamie]

Jason wrote:

Please forgive the pure ignorance of this question. I understand that
this is very basic stuff that I should probably know, but I have never
been to class to learn about this stuff, nor have I found any tutorials
that explain this stuff in simple everyday terms. I passed by
technician and general class amateur license exam by memorizing the
right buzzwords for this stuff, but not actually understanding the
concepts. I admit, I am ashamed of this fact. Here's what I have
gathered so far.

1. DC current flows through a crystal.
2. The resonance of the crystal causes the current to form waves around
the frequency of crystal
3. This new "pulsating" current is then amplified and then sent through
the crystal again. (This is called positive feedback)
4. The pulsating current is sent through a low-pass filter to "filter
out" unwanted frequencies. (That's why I said "around the frequency"
of the crystal)
5. From the filter, the current flows to an antenna which converts the
current to RF radiation.

Comments and help would be greatly appreciated.

lets break it down in a different form.

forget the crystal idea for now, that is only a source to generate
a stable frequency reference!. there are other ways.
any ways.
lets first start with the signal generator..
This generator will produce AC (alternating current/Voltage) at a rate
per second that is equal to the frequency of what you want to transmit on.
for example:
1.6 Mhz, = 1600000 times per second will an alteration of a signal
going from 0 Volts, to Full Volts+, back to 0 volts, then Full Volts-,
and then back to 0 volts completes a full cycle.
this signal is most likely then past to an amplifier to increase the
output power abilities.
it then makes it to the antenna as a sine wave (AC), at that point
the AC will generate an electro magnetic field via the antenna..
this field is powered by the AC energy you are creating.
and since its now magnetic, the principles of Unlike and like
polarities apply..
minus and minus for example repel the magnetic energy that
was there before gets pushed away.. this is how the energy actually
travels in space.

Known as a simple carrier, it really does nothing for you other than
allows another
receiver some where detect your transmitter as being there.
CW (Morse code)is a good example
systems like AM (amplitude modulation) will modify the level of this
sine wave power output to reflect the patterns of the audio frequencies.
because your transmitter frequency is so much higher than your audio
freq, many cycles of your carrier freq will be sent out in space
changing power levels in very gradual steps! but the receiver at the
other end is converting this carrier into a DC (direct Current signal)
where is the level of voltage that is changing depending on the Level of
the signal which is influenced by the audio//
etc.//

if you need a deeper detailed than that i think i can also supply that
also. this looked as simple as i could explain it.