please help with my crossroad traffic light project...

[audioguru]

Add a 0.1uF ceramic or film capacitor and a 1uF electrolytic capacitor from pin 4 to pin 1 of the 555 with short leads. These capacitors are explained in the datasheet of the 555. Didn't you read the datasheet??

Are you soldering the circuit together properly or are you using a horrible intermittent solderless breadboard?

 

[DerStrom8]

i am a bit confused what is it you want me to add and where...

Didn't you read the other comments? AG told you exactly what to put where.

 

[D@rkL0rd]

Didn't you read the other comments? AG told you exactly what to put where.

i didn't know it went to 2 page so i couldnt find it...

 

[DerStrom8]

i didn't know it went to 2 page so i couldnt find it...

Gotcha

 

[D@rkL0rd]

Add a 0.1uF ceramic or film capacitor and a 1uF electrolytic capacitor from pin 4 to pin 1 of the 555 with short leads. These capacitors are explained in the datasheet of the 555. Didn't you read the datasheet??

Are you soldering the circuit together properly or are you using a horrible intermittent solderless breadboard?

i will probably be using a breadboard...so i dont expect accuracy but i am not getting a pulse anywhere near 1 sec.and adding the cpapcitors does not help...

 

[D@rkL0rd]

what i want is can we reduce the marked phase to almost 0...

 

[DerStrom8]

Here, try using a calculator like this one:

https://www.daycounter.com/Calculators/NE555-Calculator.phtml

Or you could just do the math yourself:

Frequency=1/T= 1.44/((R1+2*R2)*C)

Low Time= 0.693*R2*C

High Time= 0.693*(R1+R2)*C

Duty Cycle= (R1+R2)/(R1+2*R2)

EDIT: Just make sure you follow the schematic shown in the link if you plan to use that calculator. Also, if you decide to add capacitors, look at the datasheet for the 555 timer to see how they're supposed to be connected.

 

[D@rkL0rd]

Here, try using a calculator like this one:

https://www.daycounter.com/Calculators/NE555-Calculator.phtml

Or you could just do the math yourself:

Frequency=1/T= 1.44/((R1+2*R2)*C)

Low Time= 0.693*R2*C

High Time= 0.693*(R1+R2)*C

Duty Cycle= (R1+R2)/(R1+2*R2)

EDIT: Just make sure you follow the schematic shown in the link if you plan to use that calculator. Also, if you decide to add capacitors, look at the datasheet for the 555 timer to see how they're supposed to be connected.

i did the calculation for high time to be 1.035s and low time to be 0.0693s i need r1 as 140k ohm and r2 as 10k ohm and capacitor of 10uf...but stil its not blinking as it should...

 

[D@rkL0rd]

I fixed the cicuit i shorted out the circuit by mistake and now its oscillating perfectly....now i had one question will the 4017 recognisr the very small loe phase from the timer...

 

[cowboybob]

....now i had one question will the 4017 recognisr the very small loe phase from the timer...

By "phase" do you mean frequency?

The 4017 will recognize, as a "count", any reasonably clean positive going pulse.

 

[audioguru]

In Post #25 the circuit is missing a resistor between pin 7 and the positive supply. Without a resistor its output pulse will be too narrow and have a duty-cycle too low.
It also DOES NOT have a 0.1uF capacitor from pin 4 to pin 1 and also DOES NOT have a 1uf electrolytic capacitor from pin 4 to pin 1. Instead the capacitors are in series which is wrong.

In post #26 why do you want to reduce the duty-cycle (you wrongly called it the phase) of the 555 clock? The CD4017 steps to the next output when the clock goes high and does nothing but wait when the clock goes low. The duty-cycle of the clock does not affect the outputs of the CD4017 except the CD4017 does not work if the duty-cycle of the clock is too low.

 

[DerStrom8]

In post #26 why do you want to reduce the duty-cycle (you wrongly called it the phase) of the 555 clock?[/QUOTE]

I was trying to figure this out as well, it's a good question. What's wrong with a near-50% duty cycle? In ideal cases you're not going to see any difference on the 4017 whether your duty cycle is 1% or 99%.

 

[D@rkL0rd]

Can u please make me undertsand the working of ic 4017 ...i think i have a majour misconception about its working...

 

[DerStrom8]

Can u please make me undertsand the working of ic 4017 ...i think i have a majour misconception about its working...

Every time the clock input goes high, the 4017 turns on the next output in the sequence. It's actually quite straightforward. You can also simulate this without using a 555 timer, but a pushbutton instead, that is connected between the clock input and V+. You will need a pull-down resistor between the clock input and ground as well, if you try using a pushbutton. Anyway, every time you press the button (send a logic 1, or HIGH pulse, to the clock input), the next output will turn on.

 

[D@rkL0rd]

Every time the clock input goes high, the 4017 turns on the next output in the sequence. It's actually quite straightforward. You can also simulate this without using a 555 timer, but a pushbutton instead, that is connected between the clock input and V+. You will need a pull-down resistor between the clock input and ground as well, if you try using a pushbutton. Anyway, every time you press the button (send a logic 1, or HIGH pulse, to the clock input), the next output will turn on.

thnx... i was thinking that when the clock goes low then only it will change the output...

 

[DerStrom8]

Here is a quick simulation I just ran to show you how the 4017 works. Obviously in the real one you'll want resistors to limit LED current and whatnot, but this should show you how it works overall. Notice that the LED changes when the input (clock) goes HIGH (the small square next to the clock input turns red).

 

[audioguru]

Why don't you READ the datasheet for the CD4017? It tells you all about it.
I copied this description from the datasheet by Texas Instruments:

 

[D@rkL0rd]

Why don't you READ the datasheet for the CD4017? It tells you all about it.
I copied this description from the datasheet by Texas Instruments:

thnax

 

[D@rkL0rd]

Why don't you READ the datasheet for the CD4017? It tells you all about it.
I copied this description from the datasheet by Texas Instruments:

i know i read this but can you make understand in a very not technical language

 

[audioguru]

I guess I am a geek because I talked in a technical language with my peers for most of my life.
Maybe someone else can patiently teach you the basics of electronics.