Need help with a sequential LED circuit using 4017 & 555

[ljcox]

LED sequencer

Yes I agree re the drive capabilities, but some one told the author to use 2 mA LEDs which should be adequate.

I'm mainly interested in the principle anyway, if he has to include drivers so be it.

Len

 

[LifeForce4]

Re: Knight rider

Hi, ljcox. The "Knight Rider" effect, as it's sometimes called, is just the back and forth pattern on the LEDs, and refers to a cheezy '80s TV show.

http://www.geocities.com/lemagicien_2000/elecpage/bounlite/bounlight.html & http://www.knightrideronline.com/krfaq.php#3-4

Adding to this is another site that has the effect called "Knight Rider".

http://www.bit-tech.net/article/82/

Kyle

 

[ljcox]

LED sequencer

Here is another option. It is based on a combination of the Laroche73 technique and an idea I almost submitted some time ago.

Circuit edited to include the base connections, a 4013 in lieu of the 4027 and a bypass capacitor.

 

[twisted_iggy]

k we got our flipflops 2day, they're 4013...im not too sure how many flipflops each of them have...teacher said it had 14pins tho....now does anyone know how i can make this work wit 2 4017s?, or willl i just have to make 2 dif circuits...and use 20 diodes for each connection to the 10 led's from both chips?....

question about the diodes still holds...will the 4017 blow or smthn if it gets pulses sent to its outputs if i have 2 4017's hooked up the same leds?...

does the flipflop only allow 1 output to b switched?, or does it swap two different outputs?...if it swaps two outputs...then i cud prolly do this wit one 4017, but from wut i understand, im thinkn it doesnt....ghad this circuit is a pain, the 4017's outputs are all out of order, not as clean as it looks in all these diagrams....makin the circuit should prove to be....fun :shock:

 

[ljcox]

LED sequencer

twisted_iggy,
The 4013 is a Dual D Type Flip Flop. It will work in the circuit I posted yesterday. Connect the D input to the Qbar output. I showed a J,K Flip Flop but it is not necessary to use a J,K since it only has to toggle.

You don't need two 4017s, my circuit is based on the laroche73 circuit that he posted some time ago. However, my circuit used transistors to drive the LEDs and so you will not have any loading problems (ie. loading of the 4017 and the 4013).

You cannot connect two 4017s to the same LED. You would need to isolate them with diades. But why use two 4017s?

The Flip Flop switches between the groups of LEDs thus allowing the LED sequence that you want.

Len

 

[twisted_iggy]

i don't quite understand that circuit u drew tho...where are the outputs from the 4017 going?, what are the b's?

 

[laroche73]

schematic

twisted-iggy,
the b's indicate the connection is made to the base of the corresponding transistor (b T1 goes to the base of transistor T1 and so on). Connections are often drawn that way (using labeled nodes) to avoid cluttering up the schematic with wires.

You seem to have some confusion about the parts count. If you have high-efficiency LEDs (2 mA drive) a direct-drive approach works fine. Although CD4000 parts have limited output drive, it increases with increasing VCC. There's not enough output drive to run the circuit at 5V, but at 12V the outputs can supply ~ 3 - 8 mA, enough to drive high-efficiency LEDs. For this scenario, you'd need (1) 4017, (1/2) of a 4013, (8 ) diodes, (10) LEDs and (2) current-limiting resistors, in addition to the 555 section (output "0" doesn't need a diode, since it's not ORed with any other outputs). You should also include a 0.1uF bypass cap across the power pins of each IC.

ljcox's circuit requires more components, but will drive standard LEDs (10-20mA). My guess is that's what you have for LEDs, a simple test can confirm it.

 

[ljcox]

LED sequencer

twisted_iggy,
I have edited my circuit above to include the base connections, the 4013 and a supply bypass capacitor (which is essential for correct operation).

Len

 

[stanley.oyugi]

can any one help out.

i need to construct a a 10 way sequential timer which will start to count immediately a receives a trigger pulse on its leg.
after completing the 10th count ity should go to rest until anonther count pulse is initated on its trigger pulse leg.
am intending to use a cmos 4017 and a 55 timer circiuts for providing the tigger pulse.
can any one help out with the circiut diagram which has a provision to lower the count and to increase the count.
thanks
my email adress stanley.oyugi@gmail.com