Hi all,

I'm fairly new here, though I have been reading posts for a while, I finally decided to register and post.

I'm trying to make a 16-step sequencer using the 10-step LED sequencer schematic that's out there which uses the 4017 decade counter IC. I've tried to cascade two 4017s together but the only things I can get it to do are:
1. one 4017 counts ones, the second one counts 10s
2. one 4017 advances one, then the other 4017 advances one (but has both steps on at the same time, which I don't want)
3. both 4017s simultaneously counting ones.

If I can get this thing to sequentially count to 20, I can shorten the steps to 16, which is *exactly* what I want. Help, please!!

Thanks in advance,

__________________
Phoebe =)
october71.iuma.com

 

hmm. well you could tryfinding a "flip flop" thingy.. what you need is somethign that will switch thesignal away fom the first 4107 and to the seccond 4017. as how to do that, i ahve no clue Anyone else?

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Do no meddel in the affairs of dragons, for you are tasty and go good with ketchup.

 

ok, i see this in 2 chioces.
1. you use a binary counter to 16 and a 4 to 16 line decoder.
2. use the 2 4017 with a 4013 flip flop
check the schematic

Attached Images

leds....16.jpg (54.3 KB, 1880 views)

 

Wow, thanks so much! I haven't had a chance to put this together yet because I need a larger breadboard (I have the smallest...and cheapest...one I could get). I'll probably pick another one up tonight or tomorrow and report back

Thanks again!!

__________________
Phoebe =)
october71.iuma.com

 

ARg, i was thinkigna flip flop. but i wanst sure so i didnt want to make a fool of myself! hehe

__________________
Do no meddel in the affairs of dragons, for you are tasty and go good with ketchup.

 

well.....you though of it, and i drew the schematic.
you know what it it will be nice....use 11 4017's to get the same effect with 100 leds.
i would try this, but buying 100 leds is quite expensive......

 

Want another way? I've not tried this but there's a fair chance it will work.
You need 2 - 4017chips, 2 resistors and 2 capacitors.

Wire CLK pins of both ICs together and clock them together.
Wire RESET pins of both chips together. Connect a 100nF from them to Vdd, and a 100K resistor from them to Vss. This ensures reset at switchon.
IC1 - Wire Q9 to CE
Wire 1n cap between IC1 Q8 and CE of IC2, and 22K resistor between CE and Q0 of IC1.

At switchon both ICs reset so Q0 is high. CE of IC1 is low because Q9 is low so count is enabled. CE of IC2 is high (through 100K) so IC2 is disabled.

Clock starts. IC1 counts from 0 thru to Q9. Q9 going high disables further count of that chip. But Q8 going low briefly enables CE of IC2. As CLK is still high at that moment, IC1 will count to Q1. Q0 going low enables IC2 for further counts up to Q9.

So you can count to 17 like this:
IC1 outputs Q1,2,3,4,5,6,7,8 then,
IC2 outputs Q1,2,3,4,5,6,7,8,9

Sorry no diagram - I've not mastered the upload yet!

 

hmmm...thanks! I'll give that a try and see how it goes too. I'll let you know once I have it made...

cya,

__________________
Phoebe =)
october71.iuma.com

 

what program do you use to make the circuits?

__________________
Do no meddel in the affairs of dragons, for you are tasty and go good with ketchup.

 

I'm trying TinyCad but having difficulty in saving to a format that can be used outside the application.

Is there a better one?

 

I use ExpressSCH ( www.expresspcb.com ). It can export schematic to bitmap.

Even Eagle ( www.cadsoftusa.com ) has this facility.

And both these softwares are free. Eagle has some limitations.

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"There is no way to peace, peace is the way!"

 

ops:

Ok, I know I must be doing something wrong, and I know it's because there's a couple of things I don't understand about this schematic. I tried making it last night and it wouldn't work at all. The questions I have are this:

1. The areas I've circled with black...does that little square mean that those are connected to ground?

and

2. The areas I circled in blue...what pin on the 4017 is leg #1 of the transistor supposed to attach to?

Sorry if these things should be obvious...I guess I'm not as good at reading schematics as I thought I was ops:

Thanks again,

Attached Images

schematic_210.jpg (48.8 KB, 1804 views)

__________________
Phoebe =)
october71.iuma.com

 

The use of 2 4017s to create a 16 bit sequencer is rather clumsy.

It would be much more elegant and simpler to use a 4 bit BINARY counter such as the 4516 or 4520 and a binary to 16 line decoder such as the 74C154, 4014 or 4015.

Len