newbie:Simple LED sequence?

[Bart]

Hi all,
I want to make 4 LED's light up in the following sequence (looping):
O O _ _
_ O O _
_ _ O O
O _ _ O
O O _ _
_ O O _
_ _ O O
O _ _ O

the above shows it has gone through two sequences, I'll want it to be
continuous and with variable frequency (a potentiometer?)

I've read up on 555 oscillators, logic gates (nand, nor, etc.), flip-flops,
op-amps..........
I don't know where to start. I DO have a nine volt battery and some
LEDs.
Any guidance is greatly appreciated,
Bart

 

[JeffM]

I want to make 4 LED's light up in the following sequence (looping):

O O _ _
_ O O _
_ _ O O
O _ _ O
O O _ _
_ O O _
_ _ O O
O _ _ O

I've read up on 555 oscillators, logic gates (nand, nor, etc.),
flip-flops, op-amps...
Bart

How about a 1-chip solution?
Teach yourself how to program a microcontroller:
http://groups.google.com/group/sci....ainer+atmel-AVR-butterfly+3v3-supply+20-bucks

 

[petrus bitbyter]

Hi all,
I want to make 4 LED's light up in the following sequence (looping):
O O _ _
_ O O _
_ _ O O
O _ _ O
O O _ _
_ O O _
_ _ O O
O _ _ O

the above shows it has gone through two sequences, I'll want it to be
continuous and with variable frequency (a potentiometer?)

I've read up on 555 oscillators, logic gates (nand, nor, etc.),
flip-flops,
op-amps..........
I don't know where to start. I DO have a nine volt battery and some
LEDs.
Any guidance is greatly appreciated,
Bart

---
Oops...
Forgot the ground on the power-on reset.

Also, start the thing with the pot cranked to max R. The display
should scroll at about one position change per second.
---

7555 Vcc
+-------+ |
+--|TH R|O-+
| |___ |
+-O|DIS OUT|--+
| +-------+ |
| | Vcc Vcc
+----[POT]<---+ +-----+ | |
| 1M | +----|D | | [100K]
| | | | _| | |
[1µF] +------|> S|O------+----+
| | | | _| | | |
| | | +--|Q R|O--+ | [0.1µF]

| | | | +-----+ | | |
| | | | HC74/2 | | GND

+-[<LED]--[R]-----+ | |
| | | | | |
| | | | +-----+ | |
| | | +--|D | | |
| | | | _| | |
| +------|> S|O------+
| | | | _| | |
| | | +--|Q R|O--+ |
| | | | +-----+ | |
| | | | HC74/2 | |
+-[<LED]--[R]-----+ | |
| | | | | |
| | | | +-----+ | |
| | | +--|D | | |
| | | | _| | |
| +------|> S|O--+ |
| | | | _| | |
| | | +--|Q R|O------+
| | | | +-----+ | |
| | | | HC74/2 | |
+-[<LED]--[R]-----+ | |
| | | | | |
| | | | +-----+ | |
GND | | +--|D | | |
| | | _| | |
+-|----|> S|O--+ |
| | _| |
+----|Q R|O------+
+-----+
HC74/2


The values of your LED dropping resistors will be:

Vcc - Vled
R = ------------
Iled

For your 9V supply,


Vcc - Vled 9V - 2V
R = ------------ = --------- = 350 ohms
Iled 0.02A


360 ohms is a standard 5% value, so the power they each need to
dissipate will be


(Vcc - Vled)² (9V - 2V)²
P = --------------- = ------------ ~ 0.136 watts
R 360R


so a standard 5% 360 ohm 1/4 watt carbon film resistor will be fine.

Looks good and a good explanation but... I'm missing a LED John. Or did you
leave it an excercise for the OP?

petrus bitbyter

 

[Oliver Hannaford-Day]

Hi,

I want to make 4 LED's light up in the following sequence (looping):
O O _ _
_ O O _
_ _ O O
O _ _ O
O O _ _
_ O O _
_ _ O O
O _ _ O

Ok I see your up on the 555 so I would say you should use a 555 to generate
the clock (And yes, a pot would make it so you could alter the speed) and
then for it to drive a decade counter.
Put two diodes from each output so when number 0 was selected by the counter
the two diodes would go to LED 1 and 2, number 1 would have two diodes
running to 2 and 3, etc.
I see you only want an 4 event counter so tie output 4 to the reset line.

it would go something like this:

LED1 LED2 LED3 LED4
output 0 D D
Output 1 D D
Output 2 D D
Output 3 D D
Output 4 reset line.

You could scrap the 555 for a variable resistor hooked to a capacitor and
transistor, the resistor would mean the cap would charge slowly (And as such
the voltage would climb slowly) until the voltage was such to activate the
transistor which would ground the cap and restart the sequence.. a nice
simple oscillator for you.

Good luck
Oliver Hannaford-Day
Lichfield Electronics

 

[petrus bitbyter]

Aaarrghhh!!!

I forgot the fourth LED, and the 7555's RESET is negative true...

7555
+-------+
+--|TH OUT|O-+
| |___ _| |
+-O|DIS R|O----Vcc
| +-------+ | Vcc
| | Vcc |
+----[POT]<---+ +-----+ | [100K]
| | | _| | |
| 1M | +----|D Q| | |
| | | | _| | |
[1µF] +------|> S|O------+----+
| | | | _| | | |
| | | +--|Q R|O--+ | [0.1µF]
| | | | +-----+ | | |
| | | | HC74/2 | | GND
+-[<LED]--[R]-----+ | |
| | | | | |
| | | | +-----+ | |
| | | +--|D | | |
| | | | _| | |
| +------|> S|O------+
| | | | _| | |
| | | +--|Q R|O--+ |
| | | | +-----+ | |
| | | | HC74/2 | |
+-[<LED]--[R]-----+ | |
| | | | | |
| | | | +-----+ | |
| | | +--|D | | |
| | | | _| | |
| +------|> S|O--+ |
| | | | _| | |
| | | +--|Q R|O------+
| | | | +-----+ | |
| | | | HC74/2 | |
+-[<LED]--[R]-----+ | |
| | | | | |
| | | | +-----+ | |
| | | +--|D | | |
| | | | _| | |
| +-|----|> S|O--+ |
| | | _| |
+-[<LED]--[R]---+----|Q R|O------+
| +-----+
GND HC74/2

Also, a better way to run the LEDs would be off of the Q's. The
starting (and running) sequence could be made the same as if they
were being driven by the Q's by complementing the SETs and RESETs,
but there'd no LED loads on the Q's and, consequently, no problem
with logic input thresholds being load dependent.

Wire it up the way it's shown and if you have problems with it, post
back and I'll be happy to help you get it right.

---
More problems.

HC74's aren't supposed to run on 9V, so you'd have to use something
like a 78L05 to get that 9V down to 5V if you used HCMOS, and
recalculate the LED series R's.

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 | | | |
----------+-----------------+ |
| |
+-----------------------------------+
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

petrus bitbyter

 

[arem_29]

hi!.. try this one!... its,
http://www.tpub.com/automotive.htm
the link provide infos readring music and more!...

 

[eric]

Hi I would have used a 555 with a binary up down counter.

 

[Alexander]

And You call yourself a Professional Circuit Designer???
Ok, most of the time we have solutions that are not suitable for a beginner
(PIC 10F series?).

Alexander
A.C.E. (Applied Communications Engineer)

 

[Alexander]

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.

 

[petrus bitbyter]

And You call yourself a Professional Circuit Designer???
Ok, most of the time we have solutions that are not suitable for a
beginner (PIC 10F series?).

Alexander
A.C.E. (Applied Communications Engineer)

So why shouldn't he call himself a Professional Circuit Designer? He often
contributes circuits in the electronics newsgroups.

PIC10F2xx will be suitable for fixed frequency. I'd go for a 12F675 because
there's no need for extra components but one potentiometer for the variable
frequency that was asked for.

The point is however that the OP seems to have hardly any skills in
electronics so I doubt whether he can reed the schematics we provided.
That's not to blame the OP. After all this is a "basics" group so he put a
good question on the right place. But that's also why I try to keep it as
simple as possible and leave it to the OP to ask further if he needs to.

petrus bitbyter

 

[petrus bitbyter]

And You call yourself a Professional Circuit Designer???
Ok, most of the time we have solutions that are not suitable for a
beginner (PIC 10F series?).

Alexander
A.C.E. (Applied Communications Engineer)

So why shouldn't he call himself a Professional Circuit Designer? He often
contributes circuits in the electronics newsgroups.

PIC10F2xx will be suitable for fixed frequency. I'd go for a 12F675 because
there's no need for extra components but one potentiometer for the variable
frequency that was asked for.

The point is however that the OP seems to have hardly any skills in
electronics so I doubt whether he can reed the schematics we provided.
That's not to blame the OP. After all this is a "basics" group so he put a
good question on the right place. But that's also why I try to keep it as
simple as possible and leave it to the OP to ask further if he needs to.

petrus bitbyter

 

[petrus bitbyter]

And You call yourself a Professional Circuit Designer???
Ok, most of the time we have solutions that are not suitable for a
beginner (PIC 10F series?).

Alexander
A.C.E. (Applied Communications Engineer)

So why shouldn't he call himself a Professional Circuit Designer? He often
contributes circuits in the electronics newsgroups.

PIC10F2xx will be suitable for fixed frequency. I'd go for a 12F675 because
there's no need for extra components but one potentiometer for the variable
frequency that was asked for.

The point is however that the OP seems to have hardly any skills in
electronics so I doubt whether he can reed the schematics we provided.
That's not to blame the OP. After all this is a "basics" group so he put a
good question on the right place. But that's also why I try to keep it as
simple as possible and leave it to the OP to ask further if he needs to.

petrus bitbyter

 

[ehsjr]

---
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

 

[Terry Pinnell]

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.

Agreed. I could probably have made a movie of it in the time it would
take a PIC-er to just get started! Here it is:
http://www.terrypin.dial.pipex.com/Images/LED-Sequencer4MB.wmv

 

[Alexander]

So why shouldn't he call himself a Professional Circuit Designer? He often
contributes circuits in the electronics newsgroups.

PIC10F2xx will be suitable for fixed frequency. I'd go for a 12F675
because
there's no need for extra components but one potentiometer for the
variable
frequency that was asked for.

The point is however that the OP seems to have hardly any skills in
electronics so I doubt whether he can reed the schematics we provided.
That's not to blame the OP. After all this is a "basics" group so he put a
good question on the right place. But that's also why I try to keep it as
simple as possible and leave it to the OP to ask further if he needs to.

petrus bitbyter

Exactly some people take to soon a PIC, GAL, FPGA or any other device. Most
of the times this are more experienced people who need a flexible design or
know that in the future the design could get more functions.
I had a simple design, when it was finished and in production for half a
year, the customer wanted a redesign with a lot more functions. All it took
was 2 days of programming and debugging. The PCB didn't change although the
customer thought it did .

Alexander

 

[Alexander]

So was my remark several post ago.

The fact was that I anticipated the client's inablity to know what he
wanted.
So I build it the way I could easily adapt it for his future needs.

As A mattor of Facts I suggested the sings he later wanted in the first
place, but NO way listen!

And Yes there was a nice fat check!!!

Alexander

 

[default]

You could scrap the 555 for a variable resistor hooked to a capacitor and
transistor, the resistor would mean the cap would charge slowly (And as such
the voltage would climb slowly) until the voltage was such to activate the
transistor which would ground the cap and restart the sequence.. a nice
simple oscillator for you.

Have you actually done that? Seems more likely the transistor would
gradually rise into conduction as the base voltage climbed to .6 volts
or so. At that point it would limit the voltage from rising further,
but not discharge the cap . . .

What you propose (a relaxation oscillator) would probably take more
than one transistor, or an Thryistor or Unijunction transistor.

 

[default]

Four 555's or two dual 555's or a quad monostable timer would work.

The falling output of one 555 is ac coupled into the next (the
datasheet shows how with a cap and two pull up resistors)

The outputs from the 555's are steered to two LED's via some diodes.

 

[Jasen Betts]

Have you actually done that? Seems more likely the transistor would
gradually rise into conduction as the base voltage climbed to .6 volts
or so. At that point it would limit the voltage from rising further,
but not discharge the cap . . .

use common collector configuration, (aka emitter follower)

What you propose (a relaxation oscillator) would probably take more
than one transistor, or an Thryistor or Unijunction transistor.

I think the plan was a delay after the button is released.

 

[Jasen Betts]

maybe something could be done using a transformer

I think you've got your threads mixed up. This one was for a
scrolling display and I don't recall the mention of any kind of
button...

yeah... you're right. I thought we were talking dice...

Bye.
Jasen