John Fields wrote:
On Mon, 19 Sep 2005 20:26:32 +0200, "Alexander"
wrote:


"John Fields" schreef in bericht
news
On Mon, 19 Sep 2005 17:42:01 +0200, "Alexander"
wrote:


"John Fields" schreef in bericht
m...

On Sun, 18 Sep 2005 23:22:03 +0200, "petrus bitbyter"
wrote:



Once you have a 555 clock running you can hook up an old CD4013B like
drawn
below. This type of components runs on power supplies from 3 to 20V. Of
course you have at least one problem left as these type of components
can
sink only a few mA of current. So your LEDs will be pretty dim or you
have
to use high efficiency LEDs. The series resistors can also be much lower
then calculated as the outputs have an internal resistor inside. The
best
thing you can do is using an extra IC, a CD4050B. This one contains six
buffers which are able to sink enough current to drive a LED.


Vcc 3-20V +-----+-----+-----+-----
| | | |
.-. .-. .-. .-.
| | | | | | | |
| | | | | | | |
'-' '-' '-' '-'
| | | |
| | | |
V V V V
- - - -
| | | |
| | | |
| +--------+ |
| | | |
| | +--------------+
.----. | | .---- | |
+-----|D0 Q|---+--|-----|D1 Q|---+ |
| | _| | | _| |
| +--| Q|o-----+ +--| Q|o-----+
| | '----' | '----' |
| | CD4013B(a) | CD4013B(b) |
Clock | | | |
----------+-----------------+ |
| |
+-----------------------------------+

---
Ah, yes... the quadrature encoder! Good one! It didn't even cross
my mind. I must be slipping...


--
John Fields
Professional Circuit Designer

And You call yourself a Professional Circuit Designer???

---
Yes, of course. Why shouldn't I?
---


Ok, most of the time we have solutions that are not suitable for a
beginner
(PIC 10F series?).

---
Sounds vaguely patronizing. What do you mean?

--
John Fields
Professional Circuit Designer

I didn't mean it as patronizing just as fun.
As more experienced designers we might more easily add a programmable
device.
Someone who just starts cannot do this because the programming is too
difficult.
I sometimes see a beginner add several chips with a cost of $15 or more
which can easily be replaced by one FPGA or MicroController with a total
cost of $5, and this makes the design also more flexible.


---
I understand the fascination with microcontrollers, but in an
application where one isn't warranted, it's just wasteful to design
one in. Consider the OP's application, a simple four-position
marquee scroller, and it becomes evident (to me, anyway) that $1 for
a PIC VS about fifty cents' worth of glue logic for the same
function makes the PIC unattractive. Plus, even with a free
programmer and development system there's still the learning curve
to climb.



It was another damn "use a PIC" post. Some of these posters drive
me crazy. Never a "Wow John, you sure put a lot of work into that,
nice job!" Never a complete project, with a schematic and source
code. Just "you could use a PIC". Hell, if you did what those
pic-ophiles do, your posts would say "use a soldering iron."
One thing's for sure - we can't criticize the PIC designs posted as
solutions to requests from posters. I'll tell you this, I'll put
any one of the solutions you've offered in the newsgroup against
all of the posted "PIC solutions", combined. Your solutions are
always great. Theirs are non-existant.

Ed