4017 help

Discussion in 'General Electronics Chat' started by Dominick, Dec 6, 2008.

Dec 6, 2008
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Ok after someone suggesting a 4017 counter I have put this together
I used Circuit maker 2000
SEM 1 and SEM 2 are traffic lights what I have in the schematic
works great but I wanted to know if there is a way to simplify it even more

V1 is my clock
V2,3 are one shots
any and all comments are welcome.

Dec 6, 2008
28
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Wait after thinking about it are they on shots?

3. Wendy Moderator

Mar 24, 2008
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Dec 6, 2008
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Yeah I saw that one to but I'm using the 555 timer for more than just
the traffic light an in my case the timer would be to fast.
Also after running the simulation again on mine I noticed that in mine and the same for the one you just posted is that the red turns green to soon after the opposing lights turn red.

This is my new one

5. Wendy Moderator

Mar 24, 2008
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So maybe you could give what durations you want for each light? In Bill Bowden's design the ratio is yellow 1/4 the time of the green. The 555 timer can be adjust for almost any speed you want.

My approach would be to adjust the timer when it is yellow, the rest falls into place.

Last edited: Dec 7, 2008

Dec 6, 2008
28
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True what about something like this?

7. Wendy Moderator

Mar 24, 2008
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Yours still uses 10 incriments, same as the other, so why would you want 2 4017's? In yours the yellow lasts the same amount of time as the green (an abnormal situation), whereas BB's the yellow is ¼ the duration of green. You also run the risk of both counters getting out of sequence with each other, can you say 2 Greens in both directions?

What you need to decide is how long each light stays on...

Then design for that.

Your concept of the one shots would work, but you have to figure out the parameters first.

***********

As I interpret your design you are wanting to hold the count on your second yellow, which is worse (yellow should be significantly shorter than green). I think you want to hold the count on your first yellow, which would put it between ¼ and ½ the duration of the green.

I went ahead and drew up a lighting chart of BB's circuit, which is also what you want. They only thing you are disagreeing with compaired to his is the duration of the yellow. Going though the math on his timer (I'd use a simpler timer myself, but no big deal) his increments are .7 seconds, which seems a bit fast. This can be whatever you want, of course.

• Traffic Light Sequence.GIF
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Last edited: Dec 7, 2008
8. Wendy Moderator

Mar 24, 2008
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I was just going though remembering how long lights seem to last for me, I'm thinking a green is 30 seconds, and a yellow is 4 seconds. The red follows the first two.

BB's design would be Green 16 seconds, yellow 4 seconds if the clock were adjusted to match this. So this suggests you want the yellow to be significantly shorter than the standard increment, which is what the monostable is for. Using my numbers the clock would be 7½ seconds per count, with the monostable used to shorten the yellow to the 4 seconds. Does this sound about right to you?

I'm going to assume your SEM1 and SEM2 have drivers in them. BB's circuit managed to incorporate his drivers and logic into the transistors at the same time. You'll note I haven't drawn any schematics yet (anyone who knows me knows there would be 1 or 2 posted by now), I'm assuming you want to to this yourself.

The 4017 is a nifty little chippie. I've used it several ways myself. It can drive 10ma (don't recommend it), but I have used it on a little light chaser that has lasted over 20 years. Here was another use that was pretty similar...

Last edited: Dec 7, 2008

Dec 6, 2008
28
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I do see what your saying but, in mine the green is 6 step, yellow is 2 step,
red is 2 step last step of red forces a hold on that chips clock and triggers
the 555 resetting other chip.

Chip one starts off on green second starts off on red not to sure but I
don't think ill have green on both sides. Now I was using two chips for a resin
but after thinking about it might be doable with one.

Here's the thing I need on the north/south a red light trigger
on the east and west i need a green light trigger both feed into a 3 input and gate.

*note* The one chip design will have one light go from yellow to red soon as it hit red green of opposing side would show real life when one hits red
the opposing side holds red for a step. Correct?

10. Wendy Moderator

Mar 24, 2008
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2,952
Red = Green + Yellow

I don't see how you can get away from that.

I keep saying this, you have to think in terms of time. It doesn't have to be symmetrical, but you have to lay out a timeline, the rest will follow naturally. This is core to any design work, define the parameters precisely, then design to fit the parameters. I would suggest using a table similar to the LED chart I made, and fill in seconds per LED. After you do this THEN work of the schematic.