Anotehr Basic Q. re: a circuit

K

Kris Krieger

Guest
Sorry for another stupid question, but, I'm looking at this
http://www.maxim-ic.com/appnotes.cfm/an_pk/1750
and can't figure out whether I can ignore, or whether I need to add in some
modification of something like this
http://www.instructables.com/id/S8Q5N9QFHTAIQK7/
where the first diagram says
" PWM Dimming 0 to 3.3HZ f>15KHz 0%=shdn 100%=20mA "

A clue would be appreciated - especially since I don't know whetehr they
mean dimming as in a Dimmer Switch on a lamp, or whether they mean
something entirely different...

Thanks in advance -

- Kris
 
"Kris Krieger"
Sorry for another stupid question, but, I'm looking at this
http://www.maxim-ic.com/appnotes.cfm/an_pk/1750
and can't figure out whether I can ignore, or whether I need to add in
some
modification of something like this
http://www.instructables.com/id/S8Q5N9QFHTAIQK7/
where the first diagram says
" PWM Dimming 0 to 3.3HZ f>15KHz 0%=shdn 100%=20mA "

A clue would be appreciated - especially since I don't know whetehr they
mean dimming as in a Dimmer Switch on a lamp, or whether they mean
something entirely different...
Click to expand...

** The CTRL input operates to dim the LEDs with a 0 to 3.3 volts variable
DC input, which can be created by filtering a PWM signal as shown or any
other way you like - eg with a 3.3 volt supply and a pot.




...... Phil
 
"Kris Krieger"


http://www.instructables.com/id/S8Q5N9QFHTAIQK7/


** Completely absurd schem, has a motor being driven by the discharge
transistor of a 555 ?

" Madulation " = ROTFL !!

God there is some dire shit published on the internet.




..... Phil
 
"Phil Allison" <philallison@tpg.com.au> wrote in
news:6fnau0FcgjgqU1@mid.individual.net:

"Kris Krieger"

Sorry for another stupid question, but, I'm looking at this
http://www.maxim-ic.com/appnotes.cfm/an_pk/1750
and can't figure out whether I can ignore, or whether I need to add
in some
modification of something like this
http://www.instructables.com/id/S8Q5N9QFHTAIQK7/
where the first diagram says
" PWM Dimming 0 to 3.3HZ f>15KHz 0%=shdn 100%=20mA "

A clue would be appreciated - especially since I don't know whetehr
they mean dimming as in a Dimmer Switch on a lamp, or whether they
mean something entirely different...


** The CTRL input operates to dim the LEDs with a 0 to 3.3 volts
variable DC input, which can be created by filtering a PWM signal as
shown or any other way you like - eg with a 3.3 volt supply and a
pot.




..... Phil
Click to expand...
In the Datasheet for the IC, in the chart describing the Pins, for CTRL, it
says:
"Brightness/Shutdown dualmode control input. LED brightness and IC
shutdown are controlled by the voltage on CTRL. VOltage between 250mV and
5.5V or (V+ + 2V), whichever is less, adjust the brightness from dim to
bright, respectively. To put the IC into shutdown, drive below 100mV or
connect to GRND."

So, for a low-voltage light (2 or three 1.2V NiMH batteries, 1500mA to
2500mA), that means it's jsut personal choice rather than mandatory to add
in the dimmer?, IOW, I can either add in a dimmer, or just connect the pin
to the ground/out terminal?

Sorry, I'm very much a beginner still, and the Appliocation Notes aren't
clear to me re: whether teh dimming is optional or required...

Thanks!

- Kris
 
"Phil Allison" <philallison@tpg.com.au> wrote in news:6fnbnoFc7g9mU1
@mid.individual.net:

"Kris Krieger"


http://www.instructables.com/id/S8Q5N9QFHTAIQK7/


** Completely absurd schem, has a motor being driven by the discharge
transistor of a 555 ?

" Madulation " = ROTFL !!

God there is some dire shit published on the internet.




.... Phil
Click to expand...
Makes it hard on us "self-teaching rubes" =:-o

I was trying to learn about PWM and Googled "pulse width modulation"
looking for some "how to's" that might clarify the app note I'd metioned.

Others in the NG (Ed, I think) had mentioned using "PWM" to turn the LEDs
on and off rapidly so as to make them look, to the human eye, like they'er
constantly on, but saving aabout 50% of the actual power being used by the
LEDs, so I was trying to figure out whetehr that is what the particualr App
Note meant by "PWM".

I evidently need to look at search results with a lot of skepticism :(
Better to know that, than not know it, thanks!

- Kris
 
"Kris Krieger"
"Phil Allison"


Sorry for another stupid question, but, I'm looking at this
http://www.maxim-ic.com/appnotes.cfm/an_pk/1750
and can't figure out whether I can ignore, or whether I need to add
in some
modification of something like this
http://www.instructables.com/id/S8Q5N9QFHTAIQK7/
where the first diagram says
" PWM Dimming 0 to 3.3HZ f>15KHz 0%=shdn 100%=20mA "

A clue would be appreciated - especially since I don't know whetehr
they mean dimming as in a Dimmer Switch on a lamp, or whether they
mean something entirely different...


** The CTRL input operates to dim the LEDs with a 0 to 3.3 volts
variable DC input, which can be created by filtering a PWM signal as
shown or any other way you like - eg with a 3.3 volt supply and a
pot.


In the Datasheet for the IC, in the chart describing the Pins, for CTRL,
it
says:
"Brightness/Shutdown dualmode control input. LED brightness and IC
shutdown are controlled by the voltage on CTRL. VOltage between 250mV and
5.5V or (V+ + 2V), whichever is less, adjust the brightness from dim to
bright, respectively. To put the IC into shutdown, drive below 100mV or
connect to GRND."

So, for a low-voltage light (2 or three 1.2V NiMH batteries, 1500mA to
2500mA), that means it's jsut personal choice rather than mandatory to add
in the dimmer?, IOW, I can either add in a dimmer, or just connect the pin
to the ground/out terminal?
Click to expand...

** Why are YOU crapping on about adding a " dimmer " all the time ??

That IC has a built in dimming function which operates as stated.



..... Phil
 
"Phil Allison" <philallison@tpg.com.au> wrote in
news:6fnev2Fcg4atU1@mid.individual.net:

"Kris Krieger"
"Phil Allison"


Sorry for another stupid question, but, I'm looking at this
http://www.maxim-ic.com/appnotes.cfm/an_pk/1750
and can't figure out whether I can ignore, or whether I need to add
in some
modification of something like this
http://www.instructables.com/id/S8Q5N9QFHTAIQK7/
where the first diagram says
" PWM Dimming 0 to 3.3HZ f>15KHz 0%=shdn 100%=20mA "

A clue would be appreciated - especially since I don't know whetehr
they mean dimming as in a Dimmer Switch on a lamp, or whether they
mean something entirely different...


** The CTRL input operates to dim the LEDs with a 0 to 3.3 volts
variable DC input, which can be created by filtering a PWM signal
as shown or any other way you like - eg with a 3.3 volt supply and
a pot.


In the Datasheet for the IC, in the chart describing the Pins, for
CTRL, it
says:
"Brightness/Shutdown dualmode control input. LED brightness and IC
shutdown are controlled by the voltage on CTRL. VOltage between
250mV and 5.5V or (V+ + 2V), whichever is less, adjust the brightness
from dim to bright, respectively. To put the IC into shutdown, drive
below 100mV or connect to GRND."

So, for a low-voltage light (2 or three 1.2V NiMH batteries, 1500mA
to 2500mA), that means it's jsut personal choice rather than
mandatory to add in the dimmer?, IOW, I can either add in a dimmer,
or just connect the pin to the ground/out terminal?


** Why are YOU crapping on about adding a " dimmer " all the time ??

That IC has a built in dimming function which operates as stated.
Click to expand...
Because I'm teaching myself, and I didn't understand that - the diagram
showed it connecting to something, and I didn't understand what that
"something" is. To me, it looked like some separate IC or circuit
becasue, if it was suposed to just be connected to teh ground, I assume
it would have shown the symbol for that, rather than a circle. Now, if
sci.electronics.basics is not the place to ask basic questions, please
let me know what would be a more appropriate venue for people who are
trying to learn on their own and have similarly-basic questions, and I'll
be glad go to that NG (or forum) instead.
 
Tim Wescott <tim@seemywebsite.com> wrote in
news:p6ydnRjHRZG1OgXVnZ2dnUVZ_sednZ2d@web-ster.com:

Kris Krieger wrote:
"Phil Allison" <philallison@tpg.com.au> wrote in
news:6fnev2Fcg4atU1@mid.individual.net:

"Kris Krieger"
"Phil Allison"
Sorry for another stupid question, but, I'm looking at this
http://www.maxim-ic.com/appnotes.cfm/an_pk/1750
and can't figure out whether I can ignore, or whether I need to
add in some
modification of something like this
http://www.instructables.com/id/S8Q5N9QFHTAIQK7/
where the first diagram says
" PWM Dimming 0 to 3.3HZ f>15KHz 0%=shdn 100%=20mA "

A clue would be appreciated - especially since I don't know
whetehr they mean dimming as in a Dimmer Switch on a lamp, or
whether they mean something entirely different...

** The CTRL input operates to dim the LEDs with a 0 to 3.3 volts
variable DC input, which can be created by filtering a PWM signal
as shown or any other way you like - eg with a 3.3 volt supply
and a pot.

In the Datasheet for the IC, in the chart describing the Pins, for
CTRL, it
says:
"Brightness/Shutdown dualmode control input. LED brightness and IC
shutdown are controlled by the voltage on CTRL. VOltage between
250mV and 5.5V or (V+ + 2V), whichever is less, adjust the
brightness from dim to bright, respectively. To put the IC into
shutdown, drive below 100mV or connect to GRND."

So, for a low-voltage light (2 or three 1.2V NiMH batteries, 1500mA
to 2500mA), that means it's jsut personal choice rather than
mandatory to add in the dimmer?, IOW, I can either add in a dimmer,
or just connect the pin to the ground/out terminal?

** Why are YOU crapping on about adding a " dimmer " all the time ??

That IC has a built in dimming function which operates as stated.


Because I'm teaching myself, and I didn't understand that - the
diagram showed it connecting to something, and I didn't understand
what that "something" is. To me, it looked like some separate IC or
circuit becasue, if it was suposed to just be connected to teh
ground, I assume it would have shown the symbol for that, rather than
a circle. Now, if sci.electronics.basics is not the place to ask
basic questions, please let me know what would be a more appropriate
venue for people who are trying to learn on their own and have
similarly-basic questions, and I'll be glad go to that NG (or forum)
instead.

Yes this is the right group.

One of the basics of learning from newsgroups is that you'll get some
very negative emotions in your responses, sometimes.

If you get on to google groups and read a sampling of Phil's posts
you'll realize that this one is really quite positive.
Click to expand...
I almost never Google past posts - I spend way too much time at the
computer as it is <LOL!> No, seriously, though, thanks for your note -
and yup, usenet is definitely a grab-bag, although I *have* gotten some
really good answers over the past several weeks from several people,
which *has* helped me understand a lot more than I had, and also has
given me much better search terms to use :) - OTOH I was honestly
serious as to asking whether this is the right group for the question I
was asking. I've tried to be up-front re: the depth and extent of my
lack of knowledge, and the fact that I'm trying to teach myself, but
maybe that didn't come through - if there is a better venue, I'd
appreciate knowing that.

I've seent hat "circle" a fe wtimes on circuit drawings, tho', and I
havent' seen it explained in the resurces I have currently, so it always
confuses me, since it looks to me like it means "add more stuff here".

Well, my books should get here is a few days (delivery was probably set
back a bit by Eduardo, alhtough he seems to have shed his wolf-skin, at
least in my area, mainly delivering a steady, soaking rain with only
brief torrents). Hopefully, the new texts will give me a good dose of
enlightenment ;)


- Kris
 
"John Fields"

It represents a connection, so that's right.

The upper one is where the supply voltage is connected to the circuit
and the lower one is where the dimming signal is connected.

The dimming signal can be either 0V to 3.3VDC or a 3.3V high signal
with a frequency higher than 15kHz and a variable duty cycle.
Click to expand...

** The OP has been given that info twice already.

However, he simply cannot comprehend it.




..... Phil
 
<mrdarrett@gmail.com
"Phil Allison"
"Kris Krieger"

http://www.instructables.com/id/S8Q5N9QFHTAIQK7/

** Completely absurd schem, has a motor being driven by the discharge
transistor of a 555 ?

" Madulation " = ROTFL !!

God there is some dire shit published on the internet.

.... Phil


From Pin 7, too, not Pin 3. Weird. Must be a tiny motor.

If taking output from Pin 3, max = what, 0.200 A?

What is the max current output from Pin 7?
Click to expand...

** About 7mA according to the 555 spec sheet.



...... Phil
 
John Fields <jfields@austininstruments.com> wrote in
news:sj0j94h4nl7f559bhk8p1h4e9dno41cf2h@4ax.com:

On Wed, 6 Aug 2008 11:56:25 +1000, "Phil Allison"
philallison@tpg.com.au> wrote:


"John Fields"

It represents a connection, so that's right.

The upper one is where the supply voltage is connected to the circuit
and the lower one is where the dimming signal is connected.

The dimming signal can be either 0V to 3.3VDC or a 3.3V high signal
with a frequency higher than 15kHz and a variable duty cycle.


** The OP has been given that info twice already.

However, he simply cannot comprehend it.

---
Did you learn everything you know all at once?

JF
Click to expand...
Heh.

Well, to be honest, yes, Phil is right, in that it *is* taking me a long
time to learn these things, since I'm learning on my own because 1) I
want to do a specific project and 2) just for the hell of it, because
it's piqued my curiosity.

Also, tho', you are definiitely right - learning takes time, especially
when one is learning things in one's area of greatest weakness; and,
nobody as born knowing everything. Which is why I do try to be polite -
I realize it takes people's time to read and answer questions, so I
appreciate that and do try to at least say "Thank You".

And maybe the point is more that I am at least trying to learn/understand
something new and, to me, alien and admittedly quite difficult, as
opposed to just resting in my 'comfort zone', heh <G!>


If Phil chooses to believe I'm an idiot merely because I'm tapping into
the area I'm weakest in (things related to math and physics) and
therefore not learning as quickly and easily as I can learn a foreign
language, or new computer software, or a new craft/artistic medium, or so
on, that's his perogative, although it might be interesting if I was
trying to teach him the rather large variety of things I can do/have
done, very well - I wonder whether he might struggle with those, as much
as I'm struggling with electronics, heh ;)


Meanwhile, I at least now know: the circle does mean "other stuff
connects here" ;) , so thanks for answering that. I'm still working
through things like frequencies (I admittedly have a hard time separating
that out from "radio"), but I have 2 books coming in the next couple of
days ("Practical Electronics", and a teach-yourself-electronics from
Wiley) which I'm hoping will clarify and instruct :)

- Kris
 
Charlie Siegrist <none.active@this.time.check.back.later> wrote in
news:IfadnW0cwL1npADVnZ2dnUVZ_srinZ2d@comcast.com:

On Wed, 06 Aug 2008 18:01:00 -0500, Kris Krieger wrote:

If Phil chooses to believe I'm an idiot...

Phil chooses to believe everyone is an idiot. It's his nature.
Click to expand...
If true, it's kind of sad. WHat goes around, really does come around, so
after a point, being contentious ends up being the moral equivalent of
shooting yourself in the foot.
 
Kris Krieger wrote:
"Phil Allison" <philallison@tpg.com.au> wrote in
news:6fnev2Fcg4atU1@mid.individual.net:

"Kris Krieger"
"Phil Allison"
Sorry for another stupid question, but, I'm looking at this
http://www.maxim-ic.com/appnotes.cfm/an_pk/1750
and can't figure out whether I can ignore, or whether I need to add
in some
modification of something like this
http://www.instructables.com/id/S8Q5N9QFHTAIQK7/
where the first diagram says
" PWM Dimming 0 to 3.3HZ f>15KHz 0%=shdn 100%=20mA "

A clue would be appreciated - especially since I don't know whetehr
they mean dimming as in a Dimmer Switch on a lamp, or whether they
mean something entirely different...

** The CTRL input operates to dim the LEDs with a 0 to 3.3 volts
variable DC input, which can be created by filtering a PWM signal
as shown or any other way you like - eg with a 3.3 volt supply and
a pot.

In the Datasheet for the IC, in the chart describing the Pins, for
CTRL, it
says:
"Brightness/Shutdown dualmode control input. LED brightness and IC
shutdown are controlled by the voltage on CTRL. VOltage between
250mV and 5.5V or (V+ + 2V), whichever is less, adjust the brightness
from dim to bright, respectively. To put the IC into shutdown, drive
below 100mV or connect to GRND."

So, for a low-voltage light (2 or three 1.2V NiMH batteries, 1500mA
to 2500mA), that means it's jsut personal choice rather than
mandatory to add in the dimmer?, IOW, I can either add in a dimmer,
or just connect the pin to the ground/out terminal?

** Why are YOU crapping on about adding a " dimmer " all the time ??

That IC has a built in dimming function which operates as stated.


Because I'm teaching myself, and I didn't understand that - the diagram
showed it connecting to something, and I didn't understand what that
"something" is. To me, it looked like some separate IC or circuit
becasue, if it was suposed to just be connected to teh ground, I assume
it would have shown the symbol for that, rather than a circle. Now, if
sci.electronics.basics is not the place to ask basic questions, please
let me know what would be a more appropriate venue for people who are
trying to learn on their own and have similarly-basic questions, and I'll
be glad go to that NG (or forum) instead.

Yes this is the right group.
Click to expand...

One of the basics of learning from newsgroups is that you'll get some
very negative emotions in your responses, sometimes.

If you get on to google groups and read a sampling of Phil's posts
you'll realize that this one is really quite positive.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
 
On Aug 3, 8:35 pm, "Phil Allison" <philalli...@tpg.com.au> wrote:
"Kris Krieger"

http://www.instructables.com/id/S8Q5N9QFHTAIQK7/

** Completely absurd schem, has a motor being driven by the discharge
transistor of a 555 ?

" Madulation " = ROTFL !!

God there is some dire shit published on the internet.

.... Phil
Click to expand...

From Pin 7, too, not Pin 3. Weird. Must be a tiny motor.

If taking output from Pin 3, max = what, 0.200 A?

What is the max current output from Pin 7?

Michael
 
On Tue, 05 Aug 2008 16:15:01 -0500, Kris Krieger <me@dowmuff.in>
wrote:

I almost never Google past posts - I spend way too much time at the
computer as it is <LOL!> No, seriously, though, thanks for your note -
and yup, usenet is definitely a grab-bag, although I *have* gotten some
really good answers over the past several weeks from several people,
which *has* helped me understand a lot more than I had, and also has
given me much better search terms to use :) - OTOH I was honestly
serious as to asking whether this is the right group for the question I
was asking. I've tried to be up-front re: the depth and extent of my
lack of knowledge, and the fact that I'm trying to teach myself, but
maybe that didn't come through - if there is a better venue, I'd
appreciate knowing that.

I've seent hat "circle" a fe wtimes on circuit drawings, tho', and I
havent' seen it explained in the resurces I have currently, so it always
confuses me, since it looks to me like it means "add more stuff here".
Click to expand...
---
It represents a connection, so that's right.

The upper one is where the supply voltage is connected to the circuit
and the lower one is where the dimming signal is connected.

The dimming signal can be either 0V to 3.3VDC or a 3.3V high signal
with a frequency higher than 15kHz and a variable duty cycle.

JF
 
On Wed, 6 Aug 2008 11:56:25 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

"John Fields"

It represents a connection, so that's right.

The upper one is where the supply voltage is connected to the circuit
and the lower one is where the dimming signal is connected.

The dimming signal can be either 0V to 3.3VDC or a 3.3V high signal
with a frequency higher than 15kHz and a variable duty cycle.


** The OP has been given that info twice already.

However, he simply cannot comprehend it.
Click to expand...
---
Did you learn everything you know all at once?

JF
 
On Wed, 6 Aug 2008 11:57:42 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

mrdarrett@gmail.com
"Phil Allison"
"Kris Krieger"

http://www.instructables.com/id/S8Q5N9QFHTAIQK7/

** Completely absurd schem, has a motor being driven by the discharge
transistor of a 555 ?

" Madulation " = ROTFL !!

God there is some dire shit published on the internet.

.... Phil


From Pin 7, too, not Pin 3. Weird. Must be a tiny motor.

If taking output from Pin 3, max = what, 0.200 A?

What is the max current output from Pin 7?


** About 7mA according to the 555 spec sheet.
Click to expand...
---
Not true.

Depending on how much drop you can tolerate in the 555's output it can
source or sink up to 200 mA.

http://www.nxp.com/acrobat_download/datasheets/NE_SA_SE555_C_2.pdf

JF
 
On Mon, 4 Aug 2008 13:35:24 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

"Kris Krieger"


http://www.instructables.com/id/S8Q5N9QFHTAIQK7/


** Completely absurd schem, has a motor being driven by the discharge
transistor of a 555 ?
Click to expand...
---
Why not? It's just an open collector, so it should be able to drive a
small motor OK.

Do you know how much current the discharge transistor is rated for?
---

" Madulation " = ROTFL !!

God there is some dire shit published on the internet.

---
Click to expand...
Usenet's got no shortage of it either. ;)

JF
 
mrdarrett@gmail.com wrote:

Yes, 200mA from Pin 3. The OP's circuit has the motor connected
between Vcc and Pin 7, however - not between Pin 3 and ground (or
between Pin 3 and Vcc.)
http://www.instructables.com/id/SALN0P4FHTAIQKM/
Click to expand...
Have you found a data sheet that shows the absolute maximum
current the discharge pin can pass?

The web page says its 200 mA, but I don't know what data
sheet that came from.
http://www.uoguelph.ca/~antoon/gadgets/ne555.htm

--
Regards,

John Popelish
 
John Popelish wrote:
mrdarrett@gmail.com wrote:

Yes, 200mA from Pin 3. The OP's circuit has the motor connected
between Vcc and Pin 7, however - not between Pin 3 and ground (or
between Pin 3 and Vcc.)
http://www.instructables.com/id/SALN0P4FHTAIQKM/

Have you found a data sheet that shows the absolute maximum current the
discharge pin can pass?

The web page says its 200 mA, but I don't know what data sheet that came
from.
http://www.uoguelph.ca/~antoon/gadgets/ne555.htm

Found it in the Motorola version:
Click to expand...
http://www.onsemi.com/pub_link/Collateral/MC1455-D.PDF

--
Regards,

John Popelish
 
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