U.S. Traffic Light

[carbonzit]

Ya you missed somthing.

How do you get yellow first when green is connected to Q0?

But it's not.

Here's the circuit posted above:

**broken link removed**

Q0 is connected to N/S yellow and E/W red. All the greens are connected to either Q1-Q4 or Q6-Q9.

If you mean the two N/S greens, those are on the wrong side of the Q0 connection to light (cathode-facing), right?

Unless I'm really missing something here ...

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And another thing: I know this is a nitpick that has nothing to do with traffic signals, but I don't think that circuit will work as shown. Looking at the 4017 datasheet, the high output current is, at best, 3-4 mA per output (and less than 1mA at worst). One would need to add driver transistors (easily done) to make it actually work.

 

[MrDEB]

"Q0 is connected to N/S yellow and E/W red. All the greens are connected to either Q1-Q4 or Q6-Q9."
Q4 is connected to N/S yellow
Q9 is connected to E/W yellow
Don't know where you figure otherwise.
Perhaps build said circuit on a breadboard and try it.

 

[4pyros]

Q0 is connected to N/S yellow and E/W red. All the greens are connected to either Q1-Q4 or Q6-Q9.

Wow! are you even looking at the same circuit.

In the circuit you posted the 1st output (Q0) pin #3 goes to the top diode then to the N/S green and then to E/W red and then to ground and so does Q1, 2, and 3. N/S Yellow is conected to Q4 pin10 and goes thru the E/W red LEDs to get to ground.

Andy

 

[4pyros]

Looking at the 4017 datasheet, the high output current is, at best, 3-4 mA per output (and less than 1mA at worst). One would need to add driver transistors (easily done) to make it actually work.

The TI data sheet for the CD4017B lists the Output High Source Current IOH Min. as 2.6ma with a 10 voltage supply and 6.8ma with a supply voltage of 15 volts, typ. at 25 degrees centigrade. That is minimun current supplyed witch is enough to light LEDs.
Andy

 

[DerStrom8]

Carbonzit, this schematic is correct. Make sure you are reading the labels correctly. I don't know what you are seeing, but there is nothing wrong with the connections from the chip to the LEDs.

 

[brett1405]

U.S traffic light

I finally got it working. I did it with the 4017 counter hooked to a triple 3-input OR gate and also a dual 4-input OR gate. Thanks for your replies, though, that really helped me in no way at all.

 

[carbonzit]

Carbonzit, this schematic is correct. Make sure you are reading the labels correctly. I don't know what you are seeing, but there is nothing wrong with the connections from the chip to the LEDs.

I finally figured it out. The schematic I was seeing was incorrect. In fact, it was the first one posted here.

But it was subsequently changed, and I was still viewing the old one from cache; my browser never bothered to refresh it.

Once I manually refreshed it, I got the revised version, which is in fact correct. Sorry for the confusion!

(The old one was wrong.)

 

[mbarazeen]

also you can see this post, we discussed a traffic light question long before..
https://www.electro-tech-online.com/threads/traffic-light-help-sos.99450/