9 LED's chaser with reverse using 4017

[Mr. Diode]

Hi! Can anyone help me with this problem?

I want to make a LED chaser circuit with the counter 4017. It is the circuit described in this side: http://www.doctronics.co.uk/kits.htm#chaser under "LIGHT CHASER".

The problem is that i can't find the schematic for the circuit.

I know how to make a ordinary LED chaser, but i don't know how to make it illuminate the LEDs in a pattern which chases from left to right and back again. Like this:



How do i make the 4017 chase the LED's back again, and not start at LED 1 after LED 9, but start on LED 8 (count down) ?

This is how i want the "light chain" to bee: LED1 LED2 LED3 ... LED7 LED8 LED9 then LED8 LED7 LED6 ... LED3 LED2 LED1 (repeated).


Do i need transistors for the LED's ? They are rated 2,2V 30mA (ø=3mm).

[Rob]

Welcome to the boards.

Interestingly, there's a great page on the site where you found the kit that helps with some of these questions:
http://www.doctronics.co.uk/4017.htm

But the specific question about counting up and then back down, I don't think that can even be done with this chip.  I once worked up a digital design using a few different ICs, but Macroman's analog version using the LM3914 chip has several advantages over a digital circuit, and I would suggest you take a look at that project.

The "do I need transistors" question is possible to answer if you describe a little better what your lights will look like--several LEDs? just one? The really nice thing about the LM3914, if you want just two or three LEDs per step, you can just run them in series and use a 12V supply. Unless you want more than that, you shouldn't need any transistors, but that's because the LM3914 is a driver chip. The counter chips like 4017 are probably not well suited for driving LEDs directly at high brightness without a transistor on each output.

I you want to see my pure digital version, I'll have to draw it up again and post it, but it uses a timer, an up/down 4-bit counter, an XOR gate and a demux to do all the stuff that the two chips in Macroman's circuit do. And then you'd still probably need to add transistors to start driving high-current LEDs.

[Mr. Diode]

I have found an interesting circuit here:

http://www.electronics-lab.com/projects/motor_light/035/index.html

What is 'Knightrider scanner mode'?

Coud i make it work with nine LED's if I use two 4017's?

I have nine LED's, one at each output of the 4017('s), do i need transistors?

[cpemma]

Using the steering diode (OR gate) principle from the Doctronics site (also explained here) and an expandable one-way chaser circuit like these or the one in the 4017 datasheet, you can make any number of leds go back & forth.

With 4017 logic, transistor current-boosters are advisable if you want a good bright light from your leds.

[Rob]

Clever and cheap--I like it.

[justDIY]

wow, that is a really clever, and simple solution!

heh, figures there is 'always' and 'easier' way

my answer was going to be a microcontroller, but thats like using a hand gernade to fight an ant problem.

[Mr. Diode]

Cascade

To cascade 4017 counters, I need a AND-gate.

How can i make it the easiest way? I don't want to use a chip.

Can i do it with diodes? Or transistors?


                                                                                                 


The outputs:

Can I use the diagram on this site under "10 Channel LED Sequencer":
http://ourworld.compuserve.com/homepages/Bill_Bowden/page5.htm#4017-7.gif
for the transistors and LED's?

Will it work with no resistors on the transistors bases? Won't they burn to death?



http://ourworld.compuserve.com/homepages/Bill_Bowden/4017-2.gif
Edit by Rob: took out the inline image, please don't hotlink external images.

[Rob]

Yeah, use the 18-stage sequencer just a little way down the page from the one you linked--he uses a couple diodes as an and gate. I notice he's added that drawing pretty recently.

Good question on the base resistors--I would be inclined to use them, but I'll have to consider the "Won't they burn to death?" question, I don't have an off-the-cuff response for that.

[Mr. Diode]

Look at the attached pdf-file!!

Do any of you use 'Multisim'?


What do you think?

Anything i have forgotten?

 

[Rob]

You are certainly earning your name with that design. Diodes everywhere.

At first glance, it looks great--of course the best way to know is to breadboard it and watch the smoke blinking lights. 

[Mr. Diode]

Here are some new pdf-files!

One circuit with 8 outputs, and one with 9 outputs!

See the attached files!!   



Do anyone have comments??

[Rob]

How come LEDs 1 and 9 aren't "OR'ed"?

[Anotherledmember]

my answer was going to be a microcontroller, but thats like using a hand gernade to fight an ant problem.

Well that depends on the proficiency of the builder.  Actually microcontrollers simplify designs.  Many applications do functions simpler than led scrolling using small 8 pins to 12 pins uCs.  Now of course the grenade uC solution is just overwhelming to those beginning in uCs.  But to the knowers, its a piece of cake.

I did a circuit for simple scrolling left-to-right, which required but a few parts, 1 IC, 1 resistor, 1 cap, and 8 leds.  Add 1 transistor to 16 led lines and 2 transistors for 24 led lines using same uC.  The uC cost $3.00 for single quantities.  The patterns are not just limited to one also but all you can imagine.  The dual 4017 circuits use > 36 parts while limited to a relatively fixed pattern.  Any changes require changes in hardwiring and the changes are not that much of a change.  Still learning the discrete foundation is good.

Video sample 1, and 2

[Mr. Diode]

I will not pay ANYTHING for this ciruit!

I would NEVER have bought an IC for 3.00 !!

It did'nt cost me anything to get all my 5 4017-ic's! 

I only use old components that I find on old ciruit-boards!

I have also found the LED's!

You would'nt die because you have to make a few more solderpoints!!!!!

[Mr. Diode]

How come LEDs 1 and 9 aren't "OR'ed"?

If they were OR'ed they would have stayd on twice as long as the other LED's (I think)!


Do any of you use Multisim??