• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

555 & 4017

Status
Not open for further replies.

mozikluv

New Member
:D hi guys,

Question 1. how do you connect 2 units of 555 to the clock pin of the 4017
(if possible)
Question 2. timer A operating at astable mode inputs first to the 4017, during the off state of timer A, timer B operating at mono inputs to the 4017 at the duration of the off state of timer A, is this set up possible?

:D
 

laroche73

New Member
dual-clock on 4017

Your question is a little confusing, Mozikluv. What are you trying to accomplish? Is the second 555 timer (B/mono) triggered off the first timer (A/astable), or does it have an independent trigger source?

The 4017 has two possible sources for an input clock, the Clock input and the Clock Enable input. Either one (or both) can be used as clock inputs, but they have opposite trigger polarities. A rising edge on the Clock input will increment the 4017 while the Clock Enable pin is held low, and a falling edge on the Clock Enable increments the counter while the Clock input is held high. One other difference between the two inputs, my datasheets show the Clock pin having a schmitt-trigger input, and the Clock Enable being a normal CMOS input (this may depend on the manufacturer). Hope this helps.
 

mozikluv

New Member
:D hi laroche 73,

sorry if my post had confused you, the timer B operating in mono shall be triggered by timer A which is operating in astable mode. all timing resistors will be pots so can easily make adjustments.

when i said how do i connect both timer output to the clock input of the 4017, i meant, do i connect it directly or do i have to put a component like a signal diode in between the timer output and the 4017 clock input.

:D
 

laroche73

New Member
driving one clock pin from two outputs

Hi mozikluv, no problem :) . The LM555 has a totem-pole output stage, so you do need to OR the outputs together with diodes, transistors or a logic gate in order to drive a single input. Parts like the LM311, which have open collector output stages, can have their outputs wire-ORed together (but require a pullup) since they can only sink current.

As noted above, the 4017 already has a built-in OR gate with "Clock" and "Clock_En" being the inputs (though the "Clock_En" polarity is inverted). As long as you account for the inverted "Clock_En" polarity, you could attach the output of timer "A" to the "Clock" input, and timer "B" to the "Clock_En" input. In other words, you could make use of the 4017's built-in OR clock structure instead of constructing an external one (This may not save on parts though, since you'd probably have to invert one of the timer outputs to make it work).
 

mozikluv

New Member
:D hi laroche 73,

thanx, now i can proceed playing around with the 4017. :D :D
 

Fred1

New Member
Hello;
I'll start off with the parts I am using. A 555 timer and a 4017. I am trying to set up a string of chase lights . The circuit works but not the way I want. I need the lights to start running then to slow down to a stop. Can anyone help me with a circuit for the 555. I checked out the mondstable and astable crcuits but that did not help.
Fred.
 

mariobar11

New Member
gudday, i need help who have a diagram of any power amplifier that have a power supply of 60v(+,-) 50amp, w/common ground.The reason i have to rebuild w/ this existing power supply i have.thanks..
 

mariobar11

New Member
Tnx AUDIOGURU AND SIR NIGEL GOODWIN.

My plan rebuilding an amplifier just a mere 200watts solidstate audio amplifier that i have to recycle the existing transistors and capacitors.i have no intention to maximize the capacity of the power of the transformer and our existing power supply is 220vac.
hope you can help me with this my input power of my transformer is 220vac and the output 60vac(2) & a center tap.
THANK YOU VERY VERY MUCH FOR A SUCH HELP AND VERY MUCH PLEASED WITH THIS SITE AND PEOPLE LIKE YOU OUT THERE WILLING TO HELP. MY GOD BLESS YOU OUT THERE AND MORE POWER TO THIS SITE "ELECTRO TECH"
 

Hero999

Banned
Yes, you need a cooker outlet or three phase to get that much power.
 

fahad_mahmood

New Member
hello everyone,
i have got a problem,i am using 5 4017 counters in order to flash 35 leds.but the problem is that i want these leds to be flash extremely fast but thats not happening.i am using astable configuration of 555 timer and i also made some changes in resistors and capacitor configuration of the 555 timer.but not get the result which i wanted.plz can anybody help out on this.or give the reason why its not happening.
Fahad
 

Johnny Hu

New Member
If I understood what you want, check this for the 4017 circuitry: http://www.electro-tech-online.com/custompdfs/2008/06/4017.pdf (fig7 - there are in fact 9 avaiable outputs for each 4017 in this topology, not 8 as mentioned in the pdf, so with just 4 4017 you be able to control until 36 LEDs. If you really want to control 35 LEDs, connect Q8 instead of Q9 in the last 4017)

As for the AND gates, you could use the 4081.

And for your astable 555, remember that f = 1/(.693 x C x (R1 + 2 x R2))
Here is a good tutorial about the 555: 555 Timer/Oscillator Tutorial

Enjoy it!
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top