Using 4017 as a single LED flasher

Thread Starter

Fuji

Joined Nov 8, 2014
100
Is the 4017 only limited to making chaser lights or matrix flashing? I can't get a single LED to flash on its own.

I removed all 9 LED and kept one LED alone and I am not getting a flash from the single LED. Does this mean I have to have more than one LED for the 4017 to enable flashing?
 
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MrChips

Joined Oct 2, 2009
31,088
That circuit as drawn will not work on its own. What is the purpose of Input and S1?
What signal are you applying to the clock input pin-14?
 

Thread Starter

Fuji

Joined Nov 8, 2014
100
That circuit as drawn will not work on its own. What is the purpose of Input and S1?
What signal are you applying to the clock input pin-14?
That is the same question I asked myself. I found this sample from the website it was from. I understand that the 4017 usually works with a 555 timer, but I am trying to exclude the 555 timer because it uses 4/5v to start operating, whereas the 4017 I have starts at a low voltage. There are no 40xx series that would be used on their own is what your saying?
 

MrChips

Joined Oct 2, 2009
31,088
No, no, no.

CD4017 is a counter. It does not count on its own. It needs something to count, i.e. a circuit that sends out a clocking signal.
You can create a clock signal with another circuit that can so happen to be a member of the 4000 family.
 

MrChips

Joined Oct 2, 2009
31,088
If you want a single LED to flash you don't need a 4017. You can do it with a 555 timer circuit. Or you can do it with 4001, 4011, 4106 or an inverting Schmitt trigger circuit. You can also do it with a one or two-transistor circuit.

Another simple LED flasher is called a Joule Thief that uses one transistor and runs off 1V.
 

Thread Starter

Fuji

Joined Nov 8, 2014
100
If you want a single LED to flash you don't need a 4017. You can do it with a 555 timer circuit. Or you can do it with 4001, 4011, 4106 or an inverting Schmitt trigger circuit. You can also do it with a one or two-transistor circuit.
I'll take on with 4001, 4011, and 4106. I just read about 4001. Seems descent.

I actually tried an LED flash with transistors, but I realized it consumes some power. I tried the single transistor circuit and this I found only works when the current/voltage is high. Never succeeded to light the LED around 2v. Instead of flashing, the LED fades in and then flashes. Looks calm to the eyes too.

My reason for this is since I have a schematic with no microcontroller, Im figuring out a way to detect low power with another circuit. I'll assume 40xx series would help out for flashing. That LM3909 IC is pretty expensive..and..not found in most places anymore. Too rare of an IC.

My next schematic will be having a microcontroller, so then I can forget asking these questions and do a little programming. :)
 
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absf

Joined Dec 29, 2010
1,968
Here is a lm3909 emulator using 4 transistors. I use it for fake burglar alarm when I am away from home running at 4.5V - 3x AA battery can last for a month.

LM3909diy2b.GIF lm3909.PNG

I have even made a PCB for it. But be ware that I replaced the 2n3904 & 2n3906 with Japanese equivalents.

Allen
 
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Thread Starter

Fuji

Joined Nov 8, 2014
100
why did this IC run into demise?
I ask the same question. They are still being made. On ebay they are being sold around $3 to $5 each. I just don't want to buy an IC that expensive just to flash an LED light.

I noticed that when certain IC's get obsolete or slowly dissipating from existence, the prices are jacked up when limited amounts are being made. LM3909 looks good for flashing LED's in any circuit to be honest. It reduces the amount of components to use as far as I see it.
 

ScottWang

Joined Aug 23, 2012
7,414
About the CD4017, you can using the reset pin to control the numbers of flashing led, you just connect any one of Q1~Q9 to reset then you can get the different numbers of flashing led.
The example is here.
 

Thread Starter

Fuji

Joined Nov 8, 2014
100
About the CD4017, you can using the reset pin to control the numbers of flashing led, you just connect any one of Q1~Q9 to reset then you can get the different numbers of flashing led.
The example is here.
Thank you very much that seems pretty simple to do. I'll take this to consideration.

I came across auto flashing LED's at around 0.7 seconds. Some go at 1 second/1hz. This will let me cut off half of the components I am using. Now I can just use 2 resistors, 2 zeners and an LED that auto flashes. I guess this is the simplest flashing circuit I have seen so far.

It seems the auto flashing LED's do have some circuitry inside of them. Not sure how it was made :rolleyes:
 

ScottWang

Joined Aug 23, 2012
7,414
What is the simplest LED flasher circuit?

Here are some possible circuits:
3)
The 3) circuit may not work, because it was connected to the wrong pin, the led should be connecting to b not c, and it will be as the function of a zener diode.
 
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Thread Starter

Fuji

Joined Nov 8, 2014
100
Let's see what Dick Cappels have to say.
I've tried everything posted above a while ago except for the slow RC flasher MrChips posted.


I ordered auto flashing LED's at 0.7 seconds. So basically a resistor and an LED. Done.
Isn't this good enough? Im assuming theirs small circuitry in the LED's. :D lol
 
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