Frustrated

[SparkyCal]

I find this incredibly frustrating. I am building all these circuits from the internet, and they rarely work. I don't know what I am doing wrong. This is a good example.

In this circuit, the guy explains it very thoroughly, and takes the time to show exactly how to make the connections. I did it twice, exactly as he explained it. Yet, if you look at the picture I included, the LED lights up but does not blink. I dom't get it. Any advice?

Here is the link:

The schematic is at the very start of the link, so i did not screenshot it.

Here is the circuit I built. The LED lights, but does not flash. Urrrggghh





Happy Easter to all btw.

 

[Hopup]

Since I don't know you level of proficiency, without looking circuit, you should make sure there are no shorts caused by the component legs touching each other. Second you might wanna make sure you have contact on all the points on that prototyping board. Some boards I have used are pretty poor regard to that.

Check the circuitry properly, generally it is good practice to be able to mark which wires and parts have been placed by marking for example with the colored pen if you are building bigger circuit using paper or if on computer you can use paint program to highlight those parts you have already put down.

Especially when training it is easy to forget some obvious wire when building it.

 

[Harald Kapp]

I did it twice, exactly as he explained it.

Probably not exactly, otherwise one would expect this simple circuit to work like a charm.

The LED is so bright, I can't see the wiring completely. Show us a photo with the LED off, please. Especially photographed such that we can see the wiring underneath the LED and were all the wires and pins go.

I may be wrong but it looks like the red wire from pin 8 is connected to pin 3, not pin 4 of the 555. That would explain the behavior.

 

[bertus]

Hello,

As said, the connections are not clear visible.
Also watch for the resistor, not shorting to each other.
This is basicaly the schematic you are using:



Bertus

 

[SparkyCal]

 

[SparkyCal]

I am careful about not having leads touch. They are not, although it may be hard to see that, I am on my way outy but whe n I get back, I will have a VERY VERY careful fourth look.

 

[SparkyCal]

 

[SparkyCal]

Changed the LED to blue. Still same result. The LED comes on but no blinking. If anyone has the time to replicate this on a breadboard, maybe it would be a way of proving me wrong- but I am sure I did everything right.

 

[SparkyCal]

Interesting- when I remove the capacitor entirely, the LED remains lit. ???????????/

 

[bertus]

Hello,

What are the values of R1 and R2, when you look at the schematic I posted?
It can be that the led is flashing, but so short off, that you can not see it.
I also would like to know the value of the capacitor.

Bertus

 

[Alec_t]

Do you have the bipolar version of the 555 or the CMOS version?
You don't have a current-limiting resistor in series with the LED so you are lucky it has survived so far, but it might pull the output voltage of the 555 down too much if it's the CMOS version.
What is your supply voltage?

 

[Ylli]

You don't have a current-limiting resistor in series with the LED

Yes he does, it is on the low side. Almost has to be component values or a bad 555, as the circuit looks OK.

 

[Nanren888]

Check that you don't have two of the resistors swapped. It looks as if you might have Ra and Rb swapped. From memory this would just change the timing, and not cause the symptoms that you suggest.
I can't see your images so well, but I can't make out a colour on the last bands of the resistors. They seem to have five bands total. Are they [yellow purple black orange] & [brown black black orange]? Sometimes the orange is quite indistinct, looking a bit like brown.
kOhm = 1000 Ohm.
Do you have another 555 to try, after checking values?

 

[AnalogKid]

It might be blinking very fast because of a resistor value error. If you have one, replace the timing cap with 10 uF = 22 uF and see if the circuit blinks.

Also, there is no power supply decoupling capacitor(s).

ak

 

[Audioguru]

Breadboard circuit always look like a tangle of wires all over the place. You cannot which connects to what.

 

[SparkyCal]

Maybe there is a flaw in the circuit. On the one hand, if the blinking is so fast that it is undetectable, then what's the point? And...why is it that when i remove the capacitor entirely from the circuit, the LED is still lit as before. The capacitor appears to have no effect.

To answer your question, there are three resistors involved, 100 ohms, 270 Ohms and 470 Ohms, as specified in the video.

Ohhhhhhhh,,,I think I just figured it out. The video calls for 100K and 470K I did not see the K and have been using 100 and 470. I will swap out the resistors and report back.

 

[SparkyCal]

Solved. I apologize for my stupidity. I did not notice that the first two resistors has a K beside their number. And when you hear the video, his says the word Kilo Ohms very fast, so i did not hear it. Anyway, all is well. Worked like a charm once I swapped out resistors of the correct value. I am sorry for the confusion. Thanks fort your patience.

 

[Nanren888]

The schematic in the video shows 100,ooo Ohms, 470,000 Ohms and 270 Ohms.
He says "hundred kill-ohms" if you listen carefully..
With much smaller resistors as you have used, the flash rate will be very high. About 1,000 times faster.
If it is robust, you could try moving it, or your head to see if you get a blur of flashes.
But easier to just swap resistors if you have them.

 

[Nanren888]

No apology required. We have all been there. Enjoy.

 

[Audioguru]

How can anybody understand what the guy in the video is saying?