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.electronics.design/browse_frm/thread/44ad1caf9218d30e/85bf1a1b9d9da3d7?q=looking-for-a-microprocessor-trainer+atmel-AVR-butterfly+3v3-supply+20-bucks

 

[John Fields]

On Sat, 17 Sep 2005 13:56:04 -0400, "Bart" <consultec@fuse.net>
wrote:

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

---

OK, here's something that'll work using a CMOS 555 and a couple of
dual "D" type flip-flops:


7555 Vcc
+-------+ |
+--|TH R|O-+
| |___ |
+-O|DIS OUT|--+
| +-------+ |
| | Vcc Vcc
+----[POT]<---+ +-----+ | |
| 1M | +----|D | | [100K]
| | | | _| | |
[1ľF] +------|> S|O------+----+
| | | | _| | | |
| | | +--|Q R|O--+ | [0.1ľF]
| | | | +-----+ | |
| | | | HC74/2 | |
+-[<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)˛ (9V - 2V)˛
P = --------------- = ------------ ~ 0.136 watts
R 360R


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

--
John Fields
Professional Circuit Designer

 

[John Fields]

On Sat, 17 Sep 2005 15:30:03 -0500, John Fields
<jfields@austininstruments.com> wrote:

On Sat, 17 Sep 2005 13:56:04 -0400, "Bart" <consultec@fuse.net
wrote:

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

---

OK, here's something that'll work using a CMOS 555 and a couple of
dual "D" type flip-flops:

---
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]
| | | | _| | |
[1ľF] +------|> S|O------+----+
| | | | _| | | |
| | | +--|Q R|O--+ | [0.1ľF]
| | | | +-----+ | | |

| | | | HC74/2 | | GND

-----+ | |
| | | | | |
| | | | +-----+ | |
| | | +--|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)˛ (9V - 2V)˛
P = --------------- = ------------ ~ 0.136 watts
R 360R


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

--
John Fields
Professional Circuit Designer

 

[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

 

[arem_29]

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



Bart wrote:

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

 

[default]

On Sun, 18 Sep 2005 16:48:48 +0100, "Oliver Hannaford-Day"
<oli_hd@dsl.pipex.com> wrote:

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.
--

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[default]

On Sat, 17 Sep 2005 13:56:04 -0400, "Bart" <consultec@fuse.net> wrote:

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.

--

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[Jasen Betts]

On 2005-10-03, default <default@defaulter.net> wrote:

On Sun, 18 Sep 2005 16:48:48 +0100, "Oliver Hannaford-Day"
oli_hd@dsl.pipex.com> wrote:

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 . . .

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.


--

Bye.
Jasen

 

[John Fields]

On Wed, 5 Oct 2005 18:23:53 +1300, Jasen Betts
<jasen-b@free.net.nospam.nz> wrote:

On 2005-10-03, default <default@defaulter.net> wrote:
On Sun, 18 Sep 2005 16:48:48 +0100, "Oliver Hannaford-Day"
oli_hd@dsl.pipex.com> wrote:

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 . . .

use common collector configuration, (aka emitter follower)

---
Really? Post a schematic for a single transistor emitter follower
astable multivibrator, OK?
---

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.

---
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...
--
John Fields
Professional Circuit Designer

 

[Jasen Betts]

On 2005-10-05, John Fields <jfields@austininstruments.com> wrote:

On Wed, 5 Oct 2005 18:23:53 +1300, Jasen Betts
jasen-b@free.net.nospam.nz> wrote:

On 2005-10-03, default <default@defaulter.net> wrote:
On Sun, 18 Sep 2005 16:48:48 +0100, "Oliver Hannaford-Day"
oli_hd@dsl.pipex.com> wrote:

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 . . .

use common collector configuration, (aka emitter follower)

---
Really? Post a schematic for a single transistor emitter follower
astable multivibrator, OK?

maybe something could be done using a transformer

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

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

 

[John Fields]

On Fri, 7 Oct 2005 21:10:30 +1300, Jasen Betts
<jasen-b@free.net.nospam.nz> wrote:

On 2005-10-05, John Fields <jfields@austininstruments.com> wrote:
On Wed, 5 Oct 2005 18:23:53 +1300, Jasen Betts
jasen-b@free.net.nospam.nz> wrote:

On 2005-10-03, default <default@defaulter.net> wrote:
On Sun, 18 Sep 2005 16:48:48 +0100, "Oliver Hannaford-Day"
oli_hd@dsl.pipex.com> wrote:

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 . . .

use common collector configuration, (aka emitter follower)

---
Really? Post a schematic for a single transistor emitter follower
astable multivibrator, OK?

maybe something could be done using a transformer

---
That would be more properly called a 'blocking oscillator'.

--
John Fields
Professional Circuit Designer