I have built a circuit to flash an LED using a 555 timer IC, but it doesn't flash... the LED just stays on steadily.

-- I carefully followed the instructions on a common tutorial, which is: http://www.instructables.com/id/Flashing-LED-using-555-Timer/

-- Here you can watch a video where I give a nice clear display of the circuit I built, and what the IC pins and leads all connect to. Video is at: https://youtu.be/qYDeqq9Bua4

-- I have tried it with 9V battery and also 4 AA's. Same result. I also tried with different color LEDs in case the draw is different somehow. Same result.

-- My capacitor: I forgot to mention in the video that I am using one that is "Electrolytic Cap 1uF / 50V" ... the instructions called for 1uF capacitor and this seemed to me to fit that specification.

-- I have checked the positive/negative on the LED and the capacitor. And I know that you see exposed leads to resistors around, but nothing is shorting out...

-- Here is a photo of the circuit. I'm sure very hard to see it. The video linked above(even just the first several seconds of it) might be easier to see. Photo is: photo of my circuit

-- In the tutorial I followed, linked above, this is the schematic that I I was told that we were following:

this is the schematic provided in the tutorial that I linked above.

-- As you can see, I am clearly novice at building electronics from scratch. I dabble in other IT stuff like Arduino but trying to get smarter on the electronics here.

Giant, huge thanks for your time and any help you can give!


  • \$\begingroup\$ Schematic or it didn’t happen. \$\endgroup\$
    – winny
    Mar 3, 2018 at 11:43
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    \$\begingroup\$ Welcome to EE.SE, Eric. Not many of us are going to watch a video for you and those Instructable articles are usually very long. Insert the schematic from the Instructable and post a decent photo or video screengrab of your construction into your question and you will attract a lot more attention. \$\endgroup\$
    – Transistor
    Mar 3, 2018 at 11:44
  • 1
    \$\begingroup\$ Hi -- you are right, I added both of those things above. I'm sure the photo is a headache to look at -- thx, Eric \$\endgroup\$ Mar 3, 2018 at 11:53
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    \$\begingroup\$ Measure your R1 -- it looks to me that it's much less than 470k, which means that your LED is indeed flashing, but it's too fast to see. \$\endgroup\$
    – Dave Tweed
    Mar 3, 2018 at 12:11

2 Answers 2


That doesn’t look like a 470k resistor in your photo. It looks more like a 470 ohm. Do you have a multimeter to test it?

The correct colours should be yellow, violet, black, orange in the 5 band colour code, or yellow violet yellow in the 4 band colour code.

The brown band indicated it is a 1% tolerance resistor on the 5 band colour code.

Just noticed @davetweed has made a similar comment,

  • \$\begingroup\$ Looks like 560 Ohms to me. \$\endgroup\$
    – Finbarr
    Mar 3, 2018 at 12:18
  • \$\begingroup\$ @Finbarr you may be correct, it is hard to tell on my ipad if that is green then blue, or yellow then violet. I presumed the OP picked the wrong one because it started with yellow and violet. \$\endgroup\$
    – HandyHowie
    Mar 3, 2018 at 12:21
  • \$\begingroup\$ Giant thanks for this. You are right. I have always screwed up reading the resistors. And, my luck, in my house I don't have any resistors over 10K. So I strung four of those together to make a 40K resistor just so I could see it flashing and go to bed happy. Giant thanks to all you guys for this -- \$\endgroup\$ Mar 3, 2018 at 13:10

It is a good idea to measure your resistors with an Ohmmeter before you start construction, the painted colors on these later day parts are becoming increasingly harder to determine.


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