Chaser w/off LED

Thread Starter

Icanmakeit67

Joined Sep 23, 2018
97
I am used to building novelty led chaser kits and diy circuits that chase. It’s usually a single led lighting up and moving through a line or circle as one on then off next on then of etc around or down a line of LEDs. I want a circuit to control 16 LEDs in a chaser effect that has the reverse going on. All LEDs are on and the moving effect is one led in turn goes off while it moves down the line or in my case around the circle.
Any help or direction would be helpful. Thank You
 

AnalogKid

Joined Aug 1, 2013
11,022
Any information would be helpful. If you post one of your past circuits we can comment on how to modify it. Your circuit will tell us voltage and current levels, logic polarities, etc.

For example, if you use a CD4017 running on 12 V and driving a ULN2803 as an LED driver, changing to a group of emitter followers will flip the display polarity.

ak
 

Thread Starter

Icanmakeit67

Joined Sep 23, 2018
97
The easiest way I can think of is to have a 16 bit shift register with two different initial conditions.
I’d like to pursue this thought. Thank You. From what I’m getting in answer/help over various sources this is not something anyone does. Don’t know why. I think it would be interesting
 

BobTPH

Joined Jun 5, 2013
8,922
Use the normal 4017 circuit, but connect the LEDs from the outputs to V+ instead of ground.
 
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Thread Starter

Icanmakeit67

Joined Sep 23, 2018
97
More information would be helpful.
  1. One direction or both?
  2. What happens when you get to the last LED?
  3. MCU/Arduino?
  4. CMOS?
  5. TTL?
  6. Power supply voltage?
  7. Area constraints?
A square unbroken shape. So dark LED would move around the shape constantly. Only clockwise. I’m not a coder but i have programmed a couple Pic microcontrollers with code someone was kind enough to provide. Built from stock ICs would be easier if possible. 5 vdc/USB power direct or from 9v snap batteries and a voltage regulator. Size isn’t a problem just now. Kinda a proof of concept to show effect….
 

dl324

Joined Mar 30, 2015
16,897
Built from stock ICs would be easier if possible. 5 vdc/USB power direct or from 9v snap batteries and a voltage regulator. Size isn’t a problem just now.
I'd go with the CD4017 recommendation (2 of them), with inverters (like CD4049 if current requirement is low enough) on the outputs. This would allow you to operate from 5V or 9V without requiring a voltage regulator.

It would have been helpful if you posted examples of how you implemented your moving dot displays. If you're already accustomed to using CD4017, it's just a matter of inverting the outputs.
 

Thread Starter

Icanmakeit67

Joined Sep 23, 2018
97
I'd go with the CD4017 recommendation (2 of them), with inverters (like CD4049 if current requirement is low enough) on the outputs. This would allow you to operate from 5V or 9V without requiring a voltage regulator.

It would have been helpful if you posted examples of how you implemented your moving dot displays. If you're already accustomed to using CD4017, it's just a matter of inverting the outputs.
I apologize for lack of knowledge but I just retired and always wanted to be an electronic hobbyist. I’m enrolling in my community college at a discount to senior citizens to learn. I have built kits for years but never designed my own circuits. A circuit design is next. I appreciate help and friends I’ve discovered here. Thank You
 

dl324

Joined Mar 30, 2015
16,897
I just retired and always wanted to be an electronic hobbyist
Congratulations on your retirement. I hope it was your idea.

Don't get talked into spending a lot of money on education. You're not likely to have any ROI. Many colleges offer free online classes. I've taken some at MIT: https://ocw.mit.edu/

What type of LEDs will you be using and what current do you plan to operate them at? Do you care if the brightness changes if you switch between 5V and 9V supplies?
A circuit design is next.
I thought all CD4017 datasheets showed how to cascade them. I was mistaken...

Here's something from a Motorola datasheet:
1703096786779.png
CD4017 is a useful chip. The last time I ordered, I bought 100.

CD4017 from different manufacturers use different part numbers (e.g. MC14017, HEF4017). For the most part (which shouldn't be the case), they're drop-in replacements.
 
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Thread Starter

Icanmakeit67

Joined Sep 23, 2018
97
Congratulations on your retirement. I hope it was your idea.

Don't get talked into spending a lot of money on education. You're not likely to have any ROI. Many colleges offer free online classes. I've taken some at MIT: https://ocw.mit.edu/

What type of LEDs will you be using and what current do you plan to operate them at? Do you care if the brightness changes if you switch between 5V and 9V supplies?
Well I want a low profile 5mm flat top frosted white. 20ma The brightness being medium +\- is not critical. Thanks for the education tip and yes I retired of my own choosing. Put in my 45 years.
 

dl324

Joined Mar 30, 2015
16,897
20ma The brightness being medium +\- is not critical.
LEDs used as indicators don't need to be operated at their maximum continuous current rating. If brightness is important, buy ultra brights and operate them at a lower current.

At 20mA, you can't use most logic gates to drive them. Using the suggested Darlington drivers is overkill because they're designed for half an amp. 74AC logic can sink/source 25mA, but they can't operate at 9V.

You could drive the LEDs with transistors/MOSFETs, but that add wiring and board area.

Note: I was editing my last post while you were responding to it. I posted a schematic.
 

ElectricSpidey

Joined Dec 2, 2017
2,765
Here is a simplified block diagram of the MUX version, this can be fleshed out if you are interested.

I think the biggest advantage of using the MUX on a breakout board would be ease of layout and build.

Also using the MUX version would give you the option of changing the direction with a simple SPDT toggle switch. (yes, I know you said that wasn't needed)

AAC_16_Channel_Mux.jpg

1703103214844.png
CD74HC4067, CD74HCT4067 datasheet (Rev. C) (ti.com)
CD4029B TYPES datasheet (Rev. C) (ti.com)

Please note: This circuit has a limit to the amount of current that can be used on the LEDs based on the maximum on resistance of the output channels. This should be determined by breadboarding the circuit. And white LEDs will give the best results.
 
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Thread Starter

Icanmakeit67

Joined Sep 23, 2018
97
LEDs used as indicators don't need to be operated at their maximum continuous current rating. If brightness is important, buy ultra brights and operate them at a lower current.

At 20mA, you can't use most logic gates to drive them. Using the suggested Darlington drivers is overkill because they're designed for half an amp. 74AC logic can sink/source 25mA, but they can't operate at 9V.

You could drive the LEDs with transistors/MOSFETs, but that add wiring and board area.

Note: I was editing my last post while you were responding to it. I posted a schematic.
Here is a simplified block diagram of the MUX version, this can be fleshed out if you are interested.

I think the biggest advantage of using the MUX on a breakout board would be ease of layout and build.

Also using the MUX version would give you the option of changing the direction with a simple SPDT toggle switch. (yes, I know you said that wasn't needed)

View attachment 310437

View attachment 310438
CD74HC4067, CD74HCT4067 datasheet (Rev. C) (ti.com)
CD4029B TYPES datasheet (Rev. C) (ti.com)

Please note: This circuit has a limit to the amount of current that can be used on the LEDs based on the maximum on resistance of the output channels. This should be determined by breadboarding the circuit. And white LEDs will give the best results.
Sorry, I’m just learning so study of this for awhile will be need I’m afraid
 

dl324

Joined Mar 30, 2015
16,897
Sorry, I’m just learning so study of this for awhile will be need I’m afraid
Here's a schematic for 16 LEDs. The 16 counter outputs being used will have one on at a time. The inverters on the output will implement the moving dark dot you want.

I show several options for driving the LEDs. The two transistors won't limit LED current, but the CD4049 can only sink about 8mA with a 9V supply (drops to 3mA at 5V).

EDIT: As noted in post #20, LED drive is wrong. As drawn, it's a moving dot.
1703128989558.png
Outputs Q0-8 from the first counter and Q1-7 from the second are used.

Decoupling capacitors omitted for clarity.
 
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k1ng 1337

Joined Sep 11, 2020
959
This is known as 'Knight Rider' circuit. There is a schematic at 1:44 in this video. Cascade more 4017 chips to make a circle or shape as big as you want. Play around with the pinouts for some unique patterns.

 

Thread Starter

Icanmakeit67

Joined Sep 23, 2018
97
This is known as 'Knight Rider' circuit. There is a schematic at 1:44 in this video. Cascade more 4017 chips to make a circle or shape as big as you want. Play around with the pinouts for some unique patterns.

Thanks. I’ve built many of these. I want an “off LED” that travels around a square with the rest of the LEDs on. Appreciate the thought
 

ElectricSpidey

Joined Dec 2, 2017
2,765
Here's a schematic for 16 LEDs. The 16 counter outputs being used will have one on at a time. The inverters on the output will implement the moving dark dot you want.

I show several options for driving the LEDs. The two transistors won't limit LED current, but the CD4049 can only sink about 8mA with a 9V supply (drops to 3mA at 5V).
View attachment 310458
Outputs Q0-8 from the first counter and Q1-7 from the second are used.

Decoupling capacitors omitted for clarity.
I think you are showing the wrong transistors for a "moving off" LED circuit.
 
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