Chip with simple program for Toy

[Roger Johansson]

John Larkin wrote:

Too bad newsreaders don't include a nice-checker.

Most newsreaders do. Set up a filter based on message body and give it
a bunch of foul words to look for.

When a message that fits the filter comes in the newsreader marks it
read or/and hides it.

That way you never see the messages which contain any of those words.



--
Roger J.

 

[John Popelish]

obliquez wrote:

Hiya, i'm new to this group, so i have no idea where i should post this
thread. So hopefully im posting in the right place.

Anyway, my problem is, i've got to connect a temperature sensor to a
buzzer. Sounds simple? Not so, i've gotta use a driver circuit to
connect the components. The sensor uses TTL logic output, so a driver
circuit has to be used to connect it to the buzzer, which runs on a
3-24V input.

Frankly speaking, i have no idea what i'm supposed to do. I don't know
how to figure out the values of the resistor or what transistor to use
for the driver circuit. Can anyone please please enlighten me.

It's part of my final year project, so it's really important that i get
help asap. Will be utterly grateful to anyone who can provide some
help.

In case my summary is not very clear, what i need to know now is just,
what kinda driver circuit should i use? And what are the values of the
components, i.e resistor, transistor, that i have to use to get that
driver circuit.

Argh! I'm not explaining very well. I hope you guys know what i'm
trying to say

Please please help!

You are starting in the middle. We need to start at the beginning.

What do you want to have happen relative to temperature and buzzer?

Do you have links to the data sheets or part numbers for the
temperature sensor and the buzzer?

 

[Eiffel]

John Fields a écrit:

Could you briefly explain what "fu" is?

Just "Follow Up". Never thought that "fu" followed by a newsgroupname, an
explanation about the xposting, and a redirection of the contributions to
[newsgroupname] could be offensive. Sorry.

Eiffel

 

[Rich Grise]

On Sun, 19 Jun 2005 22:19:27 -0700, obliquez wrote:

Hiya, i'm new to this group, so i have no idea where i should post this
thread. So hopefully im posting in the right place.

Anyway, my problem is, i've got to connect a temperature sensor to a
buzzer. Sounds simple? Not so, i've gotta use a driver circuit to
connect the components. The sensor uses TTL logic output, so a driver
circuit has to be used to connect it to the buzzer, which runs on a
3-24V input.

Frankly speaking, i have no idea what i'm supposed to do. I don't know
how to figure out the values of the resistor or what transistor to use
for the driver circuit. Can anyone please please enlighten me.

It's part of my final year project, so it's really important that i get
help asap. Will be utterly grateful to anyone who can provide some
help.

If you are in your "final year", then you should take the fail, and
take the course over again from the beginning, but actually attend
class and do the work.

Good Luck!
Rich

 

[Rich Grise]

On Mon, 20 Jun 2005 07:33:38 -0700, BB wrote:

Hi,
I am an engg student(first year) (electronics) I am very much
interested in electronics so can u please tell me where exactly to
start.Can u please suggest me some good books abt electronics so I can
improve my knowledge in it.

I thought that the reason for going to school is because that's where
they teach you these things anyway. Don't your teachers know what books
you're supposed to have for their classes? Didn't you sign up through
a course catalog of some kind, that would tell you which class to take
first?

What am I missing?

Thanks,
Rich

 

[Rich Grise]

On Sun, 19 Jun 2005 13:04:20 -0700, redbelly wrote:

redhat wrote:
here is the complete circuit; it is a vco
http://www.geocities.com/aezzat3/vco1.jpg
i don't know the capacitance of the varactor because it depends on (
the input voltage + Vcc-IR3) ,so how to know the resonant frequency
equation?

If you don't know the varactor capacitance, there is no way to
calculate a resonance frequency. The capacitance (as a function
of input voltage) would be found on a spec sheet, if it can be
found anywhere. Do you have a spec sheet for it? If not, have
you looked on the manufacturer's web site? Or searched with Google?

It might be helpful to know if an simplifiying approximation is
valid. Is the input signal small enough so that the capacitance
is largely determined by Vcc? Then you can use THAT capacitance
(as determined by the varactor specs) to determine the resonance
frequency.

If, on the other hand, the input alters the capacitance significantly,
then the behavior is highly nonlinear and probably a numerical
simulation is required to find the resonance. But doing that would
be well beyond the scope of what's describable in a newsgroup, and
possibly more time-consuming than measuring the resonance for a few
different values of L1 and C5.

It's a VCO. "I/P" (presumably in-put), is the DC control voltage,
then, redrawing, it's a simple Hartley oscillator with its output
shorted to VCC - wait a minute..... Maybe they're taking the output
off of ...

There's something wrong with that circuit.

But the resonant frequency is the series resonant frequency:
f = 1 / (2 * pi * sqrt(L * Ct)), where Ct is the value of the
series combination of C5 and the capacitance of D1. The capacitance
of D1 depends on the sum of the input voltage and whatever proportion
of VCC, depending on the impedance presented by the input.

Hope This Helps!
Rich

 

[Jonathan Kirwan]

On Sun, 19 Jun 2005 10:43:53 -0700, "Larry Brasfield"
<donotspam_larry_brasfield@hotmail.com> wrote:

Could someone write
out the equation for solving the total resistance of this circuit?

(R1 R2 R4 +
R1 R3 R4 +
R2 R3 R4 +
R1 R2 R5 +
R1 R3 R5 +
R2 R3 R5 +
R1 R4 R5 +
R2 R4 R5)
/
(R1 R2 +
R1 R3 +
R2 R3 +
R2 R4 +
R3 R4 +
R1 R5 +
R3 R5 +
R4 R5)

Just for the OP, the above completely lacks any analysis to help you
understand it or apply your knowledge anywhere else. In biblical
parable terms, you were "given a fish rather than being taught how to
fish."

But for a straight-forward derivation of the above, you might look
here, for example:

http://mcraefamily.com/MathHelp/PhysicsElec.htm

Jon

 

[Larry Brasfield]

"Jonathan Kirwan" <jkirwan@easystreet.com> wrote in message
news:65oeb1d7qd9sj5334tm24o8m5gveb340vs@4ax.com...

On Sun, 19 Jun 2005 10:43:53 -0700, "Larry Brasfield"
donotspam_larry_brasfield@hotmail.com> wrote:
[The OP had asked, about a 5 resistor bridge:]
Could someone write
out the equation for solving the total resistance of this circuit?

(R1 R2 R4 +
R1 R3 R4 +
R2 R3 R4 +
R1 R2 R5 +
R1 R3 R5 +
R2 R3 R5 +
R1 R4 R5 +
R2 R4 R5)
/
(R1 R2 +
R1 R3 +
R2 R3 +
R2 R4 +
R3 R4 +
R1 R5 +
R3 R5 +
R4 R5)

Just for the OP, the above completely lacks any analysis to help you
understand it or apply your knowledge anywhere else. In biblical
parable terms, you were "given a fish rather than being taught how to
fish."

Also for the OP, in case he missed the first part of my post, I had
suggested a perfectly workable way to solve the OP's problem:
| One way to solve it would be to convert the R1,R2,R3 set
| from its current Y form to the equivalent delta form. See
| http://www.answers.com/topic/y-delta-transform
| Once that is done, the topology can be step-wise converted
| using the rules you should know.
That suggestion, or its generalization into "apply transformations
where they simplify analysis", ought to count as a fishing lesson.

But for a straight-forward derivation of the above, you might look
here, for example:

http://mcraefamily.com/MathHelp/PhysicsElec.htm

Hmmm. They appear to have done the algebra I left the OP
to work out, using the approach I suggested. But that was
not the derivation of my expression, (which was exactly what
the OP requested, no more and no less.)

Here is another fishing lesson for those ready to take it:
(The blocks marked "in:" and "out:" represent input to
and output from a Mathematica session.)

in:
(* Setup node equations for the internal nodes. *)
en1 = e1(1/R1 + 1/R3 + 1/R2) == et(1/R1) + e2(1/R3);
en2 = e2(1/R4 + 1/R5 + 1/R3) == et(1/R4) + e1(1/R3);
(* Solve them for the internal node voltages. *)
cc = Simplify[Solve[ en1 && en2, { e1, e2 }]]
out:
{{e1 -> (et R2 (R3 R4 + R1 R5 + R3 R5 + R4 R5)) /

(R1 R2 R4 + R1 R3 R4 + R2 R3 R4 + R1 R2 R5 +

R1 R3 R5 + R2 R3 R5 + R1 R4 R5 + R2 R4 R5),

e2 -> -((et R3 (R1 R2 + R1 R3 + R2 R3 + R2 R4) R5) /

(R1 R2 R4 R5 - (R1 R2 + R1 R3 + R2 R3)

(R3 R4 + R3 R5 + R4 R5)))}}
in:
(* Using those node voltages, find resistance from top. *)
Rt = Simplify[et / ((et-e1)/R1 + (et-e2)/R4) /. cc[[1]] ]
out:
(R1 R2 R4 + R1 R3 R4 + R2 R3 R4 + R1 R2 R5 + R1 R3 R5 +

R2 R3 R5 + R1 R4 R5 + R2 R4 R5) /

(R1 R2 + R1 R3 + R2 R3 + R2 R4 + R3 R4 + R1 R5 + R3 R5 +

R4 R5)

For Mr. Kirwan's amusement, after the above has been
evaluated, the session can be extended as follows:
in:
(* Verify Kirwan's result with his inputs. *)
Rt /. {
R1->1200, R2->2700, R3->330, R4->1800, R5->680
} //N
out:
1306.66

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

 

[Jonathan Kirwan]

On Mon, 20 Jun 2005 19:48:46 -0700, "Larry Brasfield"
<donotspam_larry_brasfield@hotmail.com> wrote:

| One way to solve it would be to convert the R1,R2,R3 set
| from its current Y form to the equivalent delta form. See
| http://www.answers.com/topic/y-delta-transform
| Once that is done, the topology can be step-wise converted
| using the rules you should know.
That suggestion, or its generalization into "apply transformations
where they simplify analysis", ought to count as a fishing lesson.

I suppose. But I think it's quite a bit better to make a general
lesson clearer through at least one concrete example. Better still,
is if the transition from abstract to concrete (or visa versa) is
taken in several, leveled steps.

The link you provided was merely a hint, waving in the direction of
somewhere. There was no exposition on how the OP could apply the
abstraction, at all. It may have been a fishing lesson, but without
the right directions to get to the right pond, the OP might have wound
up fishing in the wrong place and quite frustrated by it, as well.

But for a straight-forward derivation of the above, you might look
here, for example:

http://mcraefamily.com/MathHelp/PhysicsElec.htm

Hmmm. They appear to have done the algebra I left the OP
to work out, using the approach I suggested. But that was
not the derivation of my expression, (which was exactly what
the OP requested, no more and no less.)

They also lead the horse to the water, so to speak, showing how to
apply the Y-delta idea to the specific case at hand. I consider this
a very important element to include, indeed.

....

By the way, what is more interesting to me is the sheer number of
useful concepts that can be independently applied to this problem,
with the same results. It's one of those problems that can be sliced
from a number of perspectives. And gathering those perspectives, all
of them, is very helpful in developing broad mental tools for
attacking various problems later on. Since the problem can be "seen"
from different perspectives, with the same answers arriving from each
of them, this kind of problem provides a nice fulcrum for developing
some skill in each and to gain a broader grasp.

I consider the general approach applied by spice to be useful over a
broader range of problems (as is evidenced well by how accurately
spice can deal with complex situations.) And while branch analysis is
vital to master, the mesh analysis will often yield less complexity
and should be mastered, as well. (Both fall under KCL, which of
course should be understood, too.) Finally, if I had to pick one of
these to _NOT_ memorize, it would be the y-delta transform since it
falls out almost trivially as a consequence of more powerful
approaches.

Of course, that's just my sense of things speaking as a hobbyist.

Jon

 

[John Popelish]

obliquez wrote:

The sensor I'm using is a liquid level sensor.

http://content.honeywell.com/sensing/prodinfo/liquidlevel/100437-en.pdf#seahttp://content.honeywell.com/sensing/prodinfo/liquidlevel/100437-en.pdf#search='honeywell%20lle%20sensor'

I am supposed to connect it to a buzzer, I've got 2 coz i'm not sure
which is more suitable.

http://sg.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=3921177&N=0

http://sg.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=3921189&N=0

Basically, I'm supposed to incoporate these components into a
container. When liquid is poured in, up to a certain level, the sensor
will 'sense' it, and the buzzer is supposed to sound.

Is this enough information?

My teacher said that since the sensor uses TTL Logic, I can't connect
the buzzer directly to the sensor. I have to use a driver circuit. And
that's where my problem lies.

Thanks

I don't think you need any additional parts except a 9 volt battery.
The sensor can operate from any supply between 5 and 12 volts. It
outputs a logic high (the positive supply voltage) when in air and a
logic low (negative supply voltage) when submersed. They have 3
leads. The red lead connects to battery positive, the blue to battery
negative and the green is the output.

If your buzzers are self oscillating (they make a tone, not just a pop
when connected to a 9 volt battery, red lead to positive) then all you
need to do is connect the black lead to the sensor output and the red
lead to the battery positive. Either buzzer should draw less than the
output current rating of 10 mA with a 9 volt supply.

 

[Larry Brasfield]

"Jonathan Kirwan" <jkirwan@easystreet.com> wrote in
message news:489fb1lpq6vroq9uf9iltc89bhrr30coud@4ax.com...

On Mon, 20 Jun 2005 19:48:46 -0700, "Larry Brasfield"
donotspam_larry_brasfield@hotmail.com> wrote:

| One way to solve it would be to convert the R1,R2,R3 set
| from its current Y form to the equivalent delta form. See
| http://www.answers.com/topic/y-delta-transform
| Once that is done, the topology can be step-wise converted
| using the rules you should know.
That suggestion, or its generalization into "apply transformations
where they simplify analysis", ought to count as a fishing lesson.

I suppose. But I think it's quite a bit better to make a general
lesson clearer through at least one concrete example. Better still,
is if the transition from abstract to concrete (or visa versa) is
taken in several, leveled steps.

I suppose I agree in the "more is better" sense. When I've been
paid to tutor individuals, that kind of attention made sense. But
when I've got deadlines to meet and errands to run, I have to
make a tradeoff in favor of letting an OP come back if more
help is needed. From his post, I had no reason to think he
would have any trouble once the delta-wye transformation
was done. Doing his work or overkilling the suggestion did
not make overall sense.

The link you provided was merely a hint, waving in the direction of
somewhere. There was no exposition on how the OP could apply the
abstraction, at all.

You're getting things backwards here. I told the OP how
to solve the problem. The link was merely a way to get
him the transformation formula and, if necessary, get him
to understand what the transformation was. If he had been
willing to look at the link, and drawn the delta in place of
the R1,R2,R3 wye, his problem would have been reduced
to the kind EE and EET students tackle every day. I see
no reason to draw out every step in that sequence.

It may have been a fishing lesson, but without
the right directions to get to the right pond, the OP might have wound
up fishing in the wrong place and quite frustrated by it, as well.

Maybe. And if he needed clarification, he could
easily have sought it.

But for a straight-forward derivation of the above, you might look
here, for example:

http://mcraefamily.com/MathHelp/PhysicsElec.htm

Hmmm. They appear to have done the algebra I left the OP
to work out, using the approach I suggested. But that was
not the derivation of my expression, (which was exactly what
the OP requested, no more and no less.)

They also lead the horse to the water, so to speak, showing how to
apply the Y-delta idea to the specific case at hand. I consider this
a very important element to include, indeed.

It's all obvious once one decides to do the transformation.

By the way, what is more interesting to me is the sheer number of
useful concepts that can be independently applied to this problem,
with the same results. It's one of those problems that can be sliced
from a number of perspectives. And gathering those perspectives, all
of them, is very helpful in developing broad mental tools for
attacking various problems later on. Since the problem can be "seen"
from different perspectives, with the same answers arriving from each
of them, this kind of problem provides a nice fulcrum for developing
some skill in each and to gain a broader grasp.

Ok. Perhaps you would be interested in finding the dual
of that bridge and seeing if it is more directly solvable.

I consider the general approach applied by spice to be useful over a
broader range of problems (as is evidenced well by how accurately
spice can deal with complex situations.) And while branch analysis is
vital to master, the mesh analysis will often yield less complexity
and should be mastered, as well. (Both fall under KCL, which of
course should be understood, too.)

In circuit analysis, it is sometimes useful to use a
combination of nodal and loop equations rather
than just one or the other.

Finally, if I had to pick one of
these to _NOT_ memorize, it would be the y-delta transform since it
falls out almost trivially as a consequence of more powerful
approaches.

Actually, the wye-delta transform is just an example
of the more general "dual" concept.

Of course, that's just my sense of things speaking as a hobbyist.

Your comments make me wonder if you have to
worry about time management.

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

 

[Jonathan Kirwan]

On Tue, 21 Jun 2005 02:53:20 -0400, John Popelish <jpopelish@rica.net>
wrote:

obliquez wrote:
The sensor I'm using is a liquid level sensor.

http://content.honeywell.com/sensing/prodinfo/liquidlevel/100437-en.pdf#seahttp://content.honeywell.com/sensing/prodinfo/liquidlevel/100437-en.pdf#search='honeywell%20lle%20sensor'

I am supposed to connect it to a buzzer, I've got 2 coz i'm not sure
which is more suitable.

http://sg.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=3921177&N=0

http://sg.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=3921189&N=0

Basically, I'm supposed to incoporate these components into a
container. When liquid is poured in, up to a certain level, the sensor
will 'sense' it, and the buzzer is supposed to sound.

Is this enough information?

My teacher said that since the sensor uses TTL Logic, I can't connect
the buzzer directly to the sensor. I have to use a driver circuit. And
that's where my problem lies.

Thanks

I don't think you need any additional parts except a 9 volt battery.
The sensor can operate from any supply between 5 and 12 volts. It
outputs a logic high (the positive supply voltage) when in air and a
logic low (negative supply voltage) when submersed.

Interestingly, I came to a confused impression in reading the data
sheet on this part.

"When no liquid is present, light from the LED is internally reflected
from the dome to the photo-transistor. When liquid covers the dome,
the effective refractive index at the dome-liquid boundary changes,
allowing some light from the LED to escape. Thus the amount of light
received by the photo-transistor is reduced and the output switches,
indicating the presence of liquid."

Since the diagram shows the photo-transistor connected one side to
ground (so it pulls low harder when more light is presented to it) and
since the Schmidt trigger isn't shown as an inverter, I tended to
conclude that the input node to the Schmidt was lower when more light
was present (which is when there is no liquid presented to the surface
of the detector.) And that, thus, the output would be low, as well,
at this time.

However, two things confused me about this. One is that I know that
some data sheets don't get the exact details of the logic right in the
diagram (inverter vs non-inverting, for example) and the other is that
the data sheet does specify the "output sink current" but not the
"output source current," which suggests strongly to me just as you
say, above.

It wasn't until I went elsewhere on the web that I discovered that you
are exactly correct about the output.

They have 3
leads. The red lead connects to battery positive, the blue to battery
negative and the green is the output.

If your buzzers are self oscillating (they make a tone, not just a pop
when connected to a 9 volt battery, red lead to positive) then all you
need to do is connect the black lead to the sensor output and the red
lead to the battery positive. Either buzzer should draw less than the
output current rating of 10 mA with a 9 volt supply.

Several things mitigate against this solution, I think. Most
importantly, this is a project and is probably designed to _show_ some
modest proficiency. Not much, I fear. But at least some. Just
getting lucky by hooking up a buzzer device to an output described
this way,

"The output is intended as a TTL compatible output signal, for
interfacing to logic systems. For interfacing with other types of
circuitry an appropriate buffer circuit must be used."

....would probably be violating the spirit of the project.

I suppose, if being fractious about it, I could also point out that
the two buzzers specify a maximum of 8-10mA and the sensor specifies a
worst case (at 80 C) of 3mA sinking drive and that any design that
depends on the accident of these matching up might be "graded down" a
bit. Also, since the OP actually says, " I don't know how to figure
out the values of the resistor or what transistor to use for the
driver circuit," I tend to assume that this is what the teacher
intends to be used in the design.

(The buzzer also specifies a nominal 12V. I suppose it can run on 5V,
but I wonder if the purpose of this is to also get the OP to actually
do a reasonable solution using two supplies, one at 5V and one at 12V.
No idea there, and no big deal either way, but it is a question that
crosses my mind.)

Finally, _if this is an electronics degree program__, I have a hard
time understanding how such a simple interface escapes what I'd
imagine should have been the appropriate training and the acquired
knowledge in the "final year." The solution seems non-critical in
nearly every regard and I have a hard time understanding how they
haven't they discussed BJT transistors operated as simple switches. I
begin to wonder things like, "what year is the 'final' year?" and
"what is this degree actually in?" and "what school, for gosh sake?"

Jon

 

[Jonathan Kirwan]

On Tue, 21 Jun 2005 07:40:43 GMT, Jonathan Kirwan
<jkirwan@easystreet.com> wrote:

Schmidt

Damn spell-checker! I typed Schmitt and it "fixed" it for me!

Jon

 

[Jonathan Kirwan]

On Tue, 21 Jun 2005 00:36:42 -0700, "Larry Brasfield"
<donotspam_larry_brasfield@hotmail.com> wrote:

snip
Of course, that's just my sense of things speaking as a hobbyist.

Your comments make me wonder if you have to
worry about time management.

A non sequitur. Worse, it might tend to make someone feel badly about
trying to help others, were I sensitive to such prying comments. (And
I have no _other_ idea what your purpose was in saying so unless it
were to add a negative element on a personal level.)

But this comment has no business being made here, Larry. None I can
see. But you are welcome to worry about my situation. That's none of
my business.

Jon

 

[Jonathan Kirwan]

On Tue, 21 Jun 2005 00:36:42 -0700, "Larry Brasfield"
<donotspam_larry_brasfield@hotmail.com> wrote:

"Jonathan Kirwan" <jkirwan@easystreet.com> wrote in
message news:489fb1lpq6vroq9uf9iltc89bhrr30coud@4ax.com...
On Mon, 20 Jun 2005 19:48:46 -0700, "Larry Brasfield"
donotspam_larry_brasfield@hotmail.com> wrote:

| One way to solve it would be to convert the R1,R2,R3 set
| from its current Y form to the equivalent delta form. See
| http://www.answers.com/topic/y-delta-transform
| Once that is done, the topology can be step-wise converted
| using the rules you should know.
That suggestion, or its generalization into "apply transformations
where they simplify analysis", ought to count as a fishing lesson.

I suppose. But I think it's quite a bit better to make a general
lesson clearer through at least one concrete example. Better still,
is if the transition from abstract to concrete (or visa versa) is
taken in several, leveled steps.

I suppose I agree in the "more is better" sense. When I've been
paid to tutor individuals, that kind of attention made sense. But
when I've got deadlines to meet and errands to run, I have to
make a tradeoff in favor of letting an OP come back if more
help is needed. From his post, I had no reason to think he
would have any trouble once the delta-wye transformation
was done. Doing his work or overkilling the suggestion did
not make overall sense.

I wasn't complaining about your post, Larry. I just felt that if the
OP wanted more exposition on the subject you brought up, there was
another site where that exposition could be better found. This is no
skin off of your neck. I see no reason why my addition is a problem
to you, or needs any defense on your part. It was not an attack.

The link you provided was merely a hint, waving in the direction of
somewhere. There was no exposition on how the OP could apply the
abstraction, at all.

You're getting things backwards here. I told the OP how
to solve the problem. The link was merely a way to get
him the transformation formula and, if necessary, get him
to understand what the transformation was. If he had been
willing to look at the link, and drawn the delta in place of
the R1,R2,R3 wye, his problem would have been reduced
to the kind EE and EET students tackle every day. I see
no reason to draw out every step in that sequence.

I was explaining why I added to your post, not criticizing it. So
again, you are just being defensive where it isn't needed. I don't
think it's necessary to defend what you did. However, I did explain
to you why I felt the need to add some more. No harm, there.

It may have been a fishing lesson, but without
the right directions to get to the right pond, the OP might have wound
up fishing in the wrong place and quite frustrated by it, as well.

Maybe. And if he needed clarification, he could
easily have sought it.

Agreed.

But for a straight-forward derivation of the above, you might look
here, for example:

http://mcraefamily.com/MathHelp/PhysicsElec.htm

Hmmm. They appear to have done the algebra I left the OP
to work out, using the approach I suggested. But that was
not the derivation of my expression, (which was exactly what
the OP requested, no more and no less.)

They also lead the horse to the water, so to speak, showing how to
apply the Y-delta idea to the specific case at hand. I consider this
a very important element to include, indeed.

It's all obvious once one decides to do the transformation.

Perhaps. I think that's a little presumptive, though.

By the way, what is more interesting to me is the sheer number of
useful concepts that can be independently applied to this problem,
with the same results. It's one of those problems that can be sliced
from a number of perspectives. And gathering those perspectives, all
of them, is very helpful in developing broad mental tools for
attacking various problems later on. Since the problem can be "seen"
from different perspectives, with the same answers arriving from each
of them, this kind of problem provides a nice fulcrum for developing
some skill in each and to gain a broader grasp.

Ok. Perhaps you would be interested in finding the dual
of that bridge and seeing if it is more directly solvable.

Do you care if I do? Would this help anyone's current question?

I consider the general approach applied by spice to be useful over a
broader range of problems (as is evidenced well by how accurately
spice can deal with complex situations.) And while branch analysis is
vital to master, the mesh analysis will often yield less complexity
and should be mastered, as well. (Both fall under KCL, which of
course should be understood, too.)

In circuit analysis, it is sometimes useful to use a
combination of nodal and loop equations rather
than just one or the other.

What's really useful is having the encompassing mental tools that
provide the flexibility to appropriately make those choices -- not
just having the tools themselves, but the knowledge about those tools
and about the unifying nature of them.

Finally, if I had to pick one of
these to _NOT_ memorize, it would be the y-delta transform since it
falls out almost trivially as a consequence of more powerful
approaches.

Actually, the wye-delta transform is just an example
of the more general "dual" concept.

I just enjoy seeing them all.

Jon

 

[John Popelish]

obliquez wrote:

Wow, I'm sorry, but i don't quite get it. Are you saying that i don't
need a buffer circuit? I can just connect the sensor directly to the
buzzer? Coz my teacher insists that i do need a driver circuit. Hence
all the questions.

There was an "if" in that advice. I can't tell from the catalog page
whether or not the buzzer is a unit that includes the driver or if it
is just a simple transducer. Touch its two leads to a 9 volt battery
and see if it pops or buzzes. If it buzzes, it includes the driver.
If it pops, than we have to come up with an oscillator driver circuit
that can be switched on or off by the output from the sensor.

I am not an undergrad. I'm not getting a degree. Where I'm from, we
have schools called Polytechinics (17-19 yr olds). So i'm not sure
what's it equivalent to in your country. =)

Since reading the other poster's reply to my answer, I am also
doubtful that I got the right sensor data. Your link locked up my
computer, so I searched Honeywell for an LLE sensor and picked the
first one on the list. Please send the part number of the device you
are using, so I can check what I told you.

 

[John Popelish]

obliquez wrote:

Erm, I'm using a 9V battery for testing. But in the final prototype, i
have to use those kinda flat batteries, like for watches?

So do i not need a driver circuit for this? But it is part of the
requirement of my project..

He says that since the sensor output is TTL logic, the buzzer cannot be
directly connected. A driver circuit must be used.

Thanks!

Find out if he is right by testing the buzzer on the battery and see

if it includes the driver or not.

 

[Larry Brasfield]

"Jonathan Kirwan" <jkirwan@easystreet.com> wrote in message
news:48hfb1hgvq471mlr7ltub8fmfd16cgvprm@4ax.com...

On Tue, 21 Jun 2005 00:36:42 -0700, "Larry Brasfield"
donotspam_larry_brasfield@hotmail.com> wrote:

snip
Of course, that's just my sense of things speaking as a hobbyist.

Your comments make me wonder if you have to
worry about time management.

A non sequitur.

Actually, coming after I explained that it made no sense to
take scarce time to give the OP more of an answer than he
has asked for, it is a sequitur. Your comments make it appear
that you think it would be better to provide way more of an
answer than appears needed, on the chance that it might do
some good. To me, that attitude indicates somebody with
plenty of time on their hands..

Worse, it might tend to make someone feel badly about
trying to help others, were I sensitive to such prying comments. (And
I have no _other_ idea what your purpose was in saying so unless it
were to add a negative element on a personal level.)

If you were sensitive, (which I had not guessed up to now),
I apologize for triggering that reaction.

But this comment has no business being made here, Larry. None I can
see. But you are welcome to worry about my situation. That's none of
my business.

Not worried, just observing. As for appropriateness, I
take no responsibility for speculative malign interpretations.

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

 

[Jonathan Kirwan]

On Tue, 21 Jun 2005 09:06:55 -0700, "Larry Brasfield"
<donotspam_larry_brasfield@hotmail.com> wrote:

"Jonathan Kirwan" <jkirwan@easystreet.com> wrote in message
news:48hfb1hgvq471mlr7ltub8fmfd16cgvprm@4ax.com...
On Tue, 21 Jun 2005 00:36:42 -0700, "Larry Brasfield"
donotspam_larry_brasfield@hotmail.com> wrote:

snip
Of course, that's just my sense of things speaking as a hobbyist.

Your comments make me wonder if you have to
worry about time management.

A non sequitur.

Actually, coming after I explained that it made no sense to
take scarce time to give the OP more of an answer than he
has asked for, it is a sequitur. Your comments make it appear
that you think it would be better to provide way more of an
answer than appears needed, on the chance that it might do
some good.

The simple fact is that it *IS* better. You haven't disputed this, at
all.

To me, that attitude indicates somebody with
plenty of time on their hands..

In other words, you are making this personal.

Worse, it might tend to make someone feel badly about
trying to help others, were I sensitive to such prying comments. (And
I have no _other_ idea what your purpose was in saying so unless it
were to add a negative element on a personal level.)

If you were sensitive, (which I had not guessed up to now),
I apologize for triggering that reaction.

About your comment, I'm not. But that is because my circumstances are
exactly as I have worked to make them and I'm quite satisfied, these
days. Were it otherwise, were I still struggling about who I am for
example, I might have taken your personal comment somewhat more
poorly. The reason I bother calling you on it is simply a matter of
my own perfunctoriness.

Frankly, I still cannot see a _positive_ reason for you to have made
it. And you've not made it any better by your explanations. It was
simply uncalled for.

But this comment has no business being made here, Larry. None I can
see. But you are welcome to worry about my situation. That's none of
my business.

Not worried, just observing. As for appropriateness, I
take no responsibility for speculative malign interpretations.

Of course not. And I've not made any. It's simply that I cannot find
any possible _positive_ interpretation for your comment.

Jon

 

[Jonathan Kirwan]

On Tue, 21 Jun 2005 11:04:54 -0400, John Popelish <jpopelish@rica.net>
wrote:

obliquez wrote:

Wow, I'm sorry, but i don't quite get it. Are you saying that i don't
need a buffer circuit? I can just connect the sensor directly to the
buzzer? Coz my teacher insists that i do need a driver circuit. Hence
all the questions.

There was an "if" in that advice. I can't tell from the catalog page
whether or not the buzzer is a unit that includes the driver or if it
is just a simple transducer. Touch its two leads to a 9 volt battery
and see if it pops or buzzes. If it buzzes, it includes the driver.
If it pops, than we have to come up with an oscillator driver circuit
that can be switched on or off by the output from the sensor.

It's a two-wire device. My usual encounter with these piezos (and my
experience *is* limited) is that the three-wire piezos require a
driver circuit and that some of the two-wire versions are just 3-wire
devices with a simple circuit in them. (The 3rd wire is for feedback
into a simpler circuit than could be used with those 2-wire devices
which don't have a built-in circuit.)

I also couldn't tell from the data sheet, though. Not for sure. But
my casual reading suggested that it might be one of those not needing
an extra circuit to drive them at the 3.5kHz rate. But that's just a
hunch.

Jon