# 555 led doesnt flash

#### ikuus111

Joined Dec 17, 2021
28

So im trying to make a 555 IC with a led flash but it just stays on at low light
the diagram its like that in the picture but I wired pin 5 with 10nf cap and also used a 12v 1A source with a 100 ohm resistor before pin 8 to reduce current
the capacitors are wired correctly
R1 is 11k , R2 is 20k, capacitor is 10uf, frequency of about 2 Hz
What could be the problem? I'm a complete beginner

Last edited:

#### dl324

Joined Mar 30, 2015
17,011
Welcome to AAC!
I'm a complete beginner
You should learn to use schematics to describe circuits. We don't need to see a breadboard unless we suspect a wiring problem.

What is the value of C1? The 100 ohm resistor isn't necessary.

#### Alec_t

Joined Sep 17, 2013
14,382
Welcome to AAC!
Try removing the 100R (the circuit will limit the current to what it needs. It won't be anywhere near 1A unless there is a fault) and swapping R1 and R2.

#### dl324

Joined Mar 30, 2015
17,011

#### ikuus111

Joined Dec 17, 2021
28
ok I removed 100 resistor and swapped R1 and R2 still doesnt flash but the led is bright

#### ikuus111

Joined Dec 17, 2021
28
pin 1 its connected to ground

#### ScottWang

Joined Aug 23, 2012
7,411
In your breadboard pin 1 doesn't appear to be connected to ground?
There is a blue wire below the C1.

#### AnalogKid

Joined Aug 1, 2013
11,148
Add another 10 uF capacitor between pins 1 and 8.

ak

#### ericgibbs

Joined Jan 29, 2010
19,015
hi ikuus,
This 555 simulator shows it working. OK.
E

Check that you have the 10uF electrolytic capacitor in the correct polarity.

#### dl324

Joined Mar 30, 2015
17,011
R1 is 11k , R2 is 20k, capacitor is 10uf, frequency of about 2 Hz
What's the point of posting a wiring diagram with most of the component values changed?

ok I removed 100 resistor and swapped R1 and R2 still doesnt flash but the led is bright
You must have a wiring error. Now we need to see a well focused picture of your breadboard.

#### eetech00

Joined Jun 8, 2013
4,007
View attachment 255371
So im trying to make a 555 IC with a led flash but it just stays on at low light
the diagram its like that in the picture but I wired pin 5 with 10nf cap and also used a 12v 1A source with a 100 ohm resistor before pin 8 to reduce current
the capacitors are wired correctly
R1 is 11k , R2 is 20k, capacitor is 10uf, frequency of about 2 Hz
What could be the problem? I'm a complete beginner
There is obviously a wiring error. Post a good photo's of the actual breadboad taken from different angles.

#### Alec_t

Joined Sep 17, 2013
14,382
There is obviously a wiring error
Or else the timing cap has a much lower than expected capacitance and the LED is flashing at a higher-than-visible rate.

#### ikuus111

Joined Dec 17, 2021
28
the capacitors are wired correctly,
the same with different capacitor
how and why to place a capacitor between 1 and 8?
i changed a bit by separating a resistor with cables so it to fits better.could put it back
i can upload photos of the breadboard but around pin 7 cables are very close to each other
if you need another photo i can make one
but arent there some common wiring mistakes?

and i tried to rotate the 555 IC in case its inverted but it didnt the led didnt light at all

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#### ericgibbs

Joined Jan 29, 2010
19,015
hi ikuus.
You do realize the Bread board track is open circuit, where the Red painted strip is missing.?
Use a wire jumper at the Red gaps.
E

#### ikuus111

Joined Dec 17, 2021
28
right

#### ikuus111

Joined Dec 17, 2021
28
also there was an unused cable I removed and forgot to recconect pin 8 to voltage but the led still doesnt flash.....

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#### ikuus111

Joined Dec 17, 2021
28
ok I finally found it, the capacitor has to be connected with the leads in different rows. thank you

#### ericgibbs

Joined Jan 29, 2010
19,015
hi,
Is this what you found for the Cap.?
E

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#### ikuus111

Joined Dec 17, 2021
28
hi,
Is this what you found for the Cap.?
E
What do you mean? That capacitor doesnt work when connected on same row

#### ericgibbs

Joined Jan 29, 2010
19,015
hi,
I know that.
That is why I was confirming that it was the capacitor you found on the same piece of track.
E