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# Blinking LED Circuit with Schematics and Explanation

February 26, 2017 By Øyvind Nydal Dahl 89 Comments

The blinking LED circuit is like the electronics version of the “Hello World”-program. It’s a simple electronic circuit that gives you a visual cue if it works. It was the first circuit I ever built, and it felt GREAT!

The goal is to make a Light Emitting Diode (LED) blink.

## Three Different Ways To Build A Blinking LED Circuit

There are several ways of making a blinking LED circuit. You can make one using relays. You can make one using transistors. Or you can make one using components like an inverter, a 555 Timer or a microcontroller.

I’m going to show you three ways to build a blinking LED circuit using:

- A relay
- A transistors
- An inverter

## Blinking an LED Using Relays

The easiest way to get a light to blink (or at least the easiest to understand) is the following:

In the above circuit you see a battery, a relay (in the red square) and a light bulb. To understand the circuit you need to understand how a relay works.

When the relay coil has power, the switch will disconnect the power from the electromagnet and connect the power to the light bulb instead so that it will light up.

But when the relay no longer has power, it will switch back and turn off the power from the light bulb and give power back to the electromagnet again.

Then the cycle starts over.

The problem with the circuit above is that it will switch so fast that you won’t actually see the light blink.

To solve this problem you can introduce a time-delay using a resistor and a capacitor.

When you apply power to the above circuit, the battery starts charging the capacitor through resistor R2.

After a moment, the relay coil pulls the relay into the other position.

This makes the LED turn ON.

Because the capacitor now is charged, it will hold the relay in this position. But the capacitor only has enough energy to keep the electromagnet in the relay powered for a little bit before it’s empty (or discharged).

When the capacitor is out of energy, the relay goes back into its original state and turns the LED OFF again.

Then the cycle repeats itself.

For this circuit with the above component values I recommend the DS2Y-S-DC5V relay or a similar one.

## Blinking Two LEDs Using Transistors

The circuit for blinking an LED using transistors is called an Astable Multivibrator.

To understand this circuit you need to know how voltages and currents behave around resistors, capacitors and diodes (which is something you can learn in Ohmify).

But, here’s the overview of what happens:

The two capacitors C1 and C2 will alternate between being charged and discharged and thereby turning the transistors ON and OFF. When a transistor is ON it allows current to flow through it so that the LED above it will light up.

I find this java applet really helpful in understanding how this circuit works.

## How To Blink An LED With An Inverter

This is probably the easiest blinking LED circuit when it comes to number of components: You only need three components for the blinking part!

But you need the resistor and LED to be blinked too of course.

I built the circuit around an inverter.

An inverter is a logical component that outputs the opposite of what it gets in. If it gets a high voltage in, it gives a low voltage out. And vice versa.

A high voltage is a voltage close to the supply voltage. A low voltage is a voltage close to zero volts.

In the circuit diagram you can see that the output of the inverter (U1) is connected back to the input with a resistor. This means that if there’s a high voltage on the input, the output will be low. But since the output is connected back to the input, the input will be low. Now that the input is low, the output will be high. That means the input will be high again, and so on…

So it will keep jumping between high and low.

To slow down the jumping back and forth, I’ve used a capacitor on the input of the inverter. The resistor R1 controls how much current that goes back to charge the capacitor on the input. The size of the resistor R1 and the capacitor C1 will, therefore, determine the blinking speed.

The inverter I used is a Schmitt Trigger Inverter. Schmitt Trigger just means that the threshold for switching from high to low is different from the threshold for switching from low to high.

## Start Building

Now, you’ve read about ’em. It’s time to start building! Find the parts you need at one of the online shops, order them and build.

You might also be interested in 9 Circuits:

9 Circuits is an eBook that will help you become great at building circuits. It has nine circuit-building challenges you’ll have to overcome. And you’ll get to build things like a game, a homemade musical instrument and a cookie-jar alarm.

The projects range from easy to medium and they’re suitable even for complete beginners.

For each circuit I’ve created a web page where you can get help with the circuit if you’re stuck.

I’ve also developed a component kit that has every component you need for building all the circuits in the book.

More info here:
https://ohmify.com/9cbook/

## Did You Build Them?

Have you built a blinking LED circuit from this article?

How did it go?

Let me know in the comment field below.

## Reader Interactions

### Comments

1. biswajit says

   July 1, 2014 at 8:39 am

   your explanation on relay circuit is not so clear…..plz elaborate schematics connection and its operation…….capacitor and relay are connected in parallel so it will always turn on the led..

   Reply

   - admin says

     September 10, 2014 at 4:29 pm

     Not sure what you mean.. The circuits are working fine.
     Oyvind

     Reply

   - domnic says

     September 27, 2014 at 12:52 pm

     always current chooses the low resistance path ,so whenever the movable part of the relay is connected to the parallel path of the led, the current prefers to flow through ‘8’ but not ‘4’, because in forward bias the led has 10-100 ohms resistance which is greater than internal resistance of wire.

     Reply

   - Jack (Cannonball) says

     February 10, 2018 at 5:37 pm

     This is a good explanation of how the relay blinker works. You need to learn how electrons flow through a circuit. Charging and discharging the capacitor slows the switching of the relay so you can see the led turn on and off.

     Reply

2. jadyn says

   September 5, 2014 at 4:26 pm

   can you make an wire circit to blink 6 lights blink

   Reply

   - admin says

     September 10, 2014 at 4:30 pm

     Absolutely =)

     Oyvind

     Reply

3. Alec says

   October 27, 2014 at 7:21 pm

   The ppage is headed “Blinking LED Circuit with Schematics and Explanation”, but there doesn’t seem to be any schematics. just the explanation and one photo.

   Reply

   - admin says

     October 27, 2014 at 8:36 pm

     There are schematics too. Try reloading the page.

     Oyvind

     Reply

4. ed says

   May 10, 2015 at 8:13 pm

   c=2000uf, R3=390ohm.Could u tell me how you choose the values.

   Reply

   - Rudy says

     May 17, 2015 at 6:18 am

     Ohm’s law is how he wound up with those values. What you need to do is pick your power supply voltage, ie:9volts, then you calculate your load current= total of all your loads, as in the loads of leds probally have around 3mA each, so you add 3mA+3mA=6mA, you then convert mA to amps 1000mA=1Amp, in this case 6mA/1000= .006 mA You now have your Volts, and your ( I )Current, so Ohm’s law states V/I = Resistance(Ohms), 9volts/.006mA=1500ohm. Study Ohm’s law, it will help out alot and save your life too!!!!!

     Reply

     - Stephen says

       December 10, 2017 at 1:51 am

       Typo error: 6 mA can’t also be .006 mA.
       Don’t confuse the beginners. 6mA=0.006 Amps. B-)

       Reply

       - Mike chishimba says

         January 1, 2019 at 6:05 am

         A have a Samsung TV locked with Keyword. What do I do to unlock it.

         Reply

5. Brian says

   May 30, 2015 at 5:06 pm

   Im trying to do a similar project, but utilizing 3 LED’s in sequence instead of two. Any ideas on how that could be accomplished utilizing a similar circuit?

   Reply

   - admin says

     February 27, 2017 at 1:19 am

     How to you want the LEDs to blink? All three ON and OFF at the same time? Only one ON at any one time?

     Best,
     Oyvind

     Reply

6. jack says

   July 31, 2015 at 12:03 am

   this is very unclear and poorly done

   Reply

   - off says

     December 12, 2016 at 11:37 am

     Perhaps you are just a poor student.

     Reply

7. james says

   February 9, 2016 at 4:13 pm

   Please give me a introduction of a blinking leD’s without arduino. Plsss..

   Reply

   - admin says

     February 27, 2017 at 1:20 am

     There’s no use of Arduino in this article. So I’m not sure what you mean.
     Best,
     Oyvind

     Reply

8. Atuh says

   May 19, 2016 at 8:48 pm

   Can I get an inverter circuit

   Reply

9. kavindu says

   June 17, 2016 at 6:33 pm

   Can you recommand me an ebook can be helpful to gain a thorough knoweldge of making electronic circuits?

   Reply

   - admin says

     June 17, 2016 at 6:50 pm

     Hey, I would of course recommend my own book =)

     You can find it here:
     http://www.build-electronic-circuits.com/products/ebook-2nd-edition

     Best,
     Oyvind

     Reply

     - kavindu says

       June 17, 2016 at 7:41 pm

       Thank you for helping me…and the java applet that you’ve mentioned earlier in blinking led lights is a great illustration…keep it up…

       Reply

10. tebu says

    October 2, 2016 at 11:19 am

    Thanks for article. Can you please explain about battery & how to power up circuit ?

    Reply

11. tebu says

    October 2, 2016 at 11:19 am

    Thanks for article. Can you please explain battery & how to power up circuit safely ?

    Reply

    - admin says

      February 27, 2017 at 1:22 am

      For the circuits in this article you don’t have to worry about safety. They all use very low power.

      Best,
      Oyvind

      Reply

12. O Pinionated says

    December 9, 2016 at 11:01 pm

    These comments seem to come mainly from “experts” who wish to glorify themselves at the expense of the site’s author.

    First, one wonders why an expert would be looking at a page for such a (presumably) simple circuit, given their expert status.

    Those seeking the “explanation” obviously missed the very obvious link to the more technical information,.

    Can you design me a blinking LED death ray? You are the king of blinking LEDs after all!
    —Guys the author of the site is trying to introduce you to some basic electrical/electronic concepts using circuits as examples to try and learn from. He’s not offering you a fish, he’s trying to teach you to fish.

    Poorly Done, etc etc etc….
    — How long did you spend on your your website, stooping from your “expert” throne into the —gutter with the rest of us, just to “Help a newb learn something” ???
    —Oh, and please Please PLEASE provide the links

    Reply

    - Stephen says

      December 10, 2017 at 2:06 am

      You might consider the questions from experts as a sort of pier review process. Weather they are self aggrandizing or not is in the mind of the reader. Our teacher is only human, and a little polite help, I would hope, would be welcomed. Some times we over look that which is obvious to us, but murky to the beginner.

      Reply

13. Ron says

    December 26, 2016 at 8:18 pm

    Thank you for publishing this online for all to use. Can I place two additional LEDs in parallel (one additional for each side of the circuit so that I end up with alternating pairs) without having to modify any part of the circuit or increase the input power? Thanks.

    Reply

    - admin says

      December 27, 2016 at 2:26 am

      Yes, you can. They might be a bit dim though. In that case, change the two 470 Ohm resistors to two 220 Ohm resistors.

      Best,
      Oyvind

      Reply

14. david mont says

    December 31, 2016 at 7:21 pm

    what value should the capacitors be

    Reply

    - admin says

      January 3, 2017 at 7:09 am

      Try with 10µF

      Best,
      Oyvind

      Reply

15. Sejal Tyagi says

    February 12, 2017 at 5:14 pm

    Thank you sir.
    It helped a lot.
    It helped me IN my physics project.

    :-)

    Reply

    - Rhemar says

      February 18, 2017 at 1:46 pm

      Can I ask? cause I also need this circuit understand well. Its also our physics project :(

      Reply

16. Rhemar says

    February 18, 2017 at 1:37 pm

    Can I see a Video making the Blinking an LED Using Relays? This is very useful in our thesis. But Iam not good in electronics. I will be very thankful sir if you help me :( I just need this for me to pass our subjects, and also to help my classmates/group mate. Iam hoping for you reply sir.

    Reply

    - admin says

      February 20, 2017 at 4:24 am

      Hey Rhemar,
      I don’t have that at the moment.

      Best,
      Oyvind

      Reply

17. Rhemar says

    February 18, 2017 at 2:38 pm

    Can I ask for the materials to be used in making the Blinking an LED Using Relays

    Reply

    - admin says

      February 27, 2017 at 1:23 am

      I’m updating the article with a better schematic and component values now.

      Best,
      Oyvind

      Reply

18. Twaha ali says

    February 28, 2017 at 9:59 am

    thank you.
    but i have a problems on how to evaluate the value of resistor ,capacitor and inductor
    ( how to analysis the circuit)

    Reply

19. Alex Melekhov says

    March 2, 2017 at 4:45 pm

    Hi Oyvind
    Please check the arrow direction on the 2-nd example with relay and capacitor. It seems to be pointing wrong contact according to the text. ;)

    Thank you,
    Alex M.

    Reply

    - admin says

      March 9, 2017 at 5:03 pm

      Thanks for your comment!
      I mixed ON and OFF there. Fixed it now. Was that what you meant?

      Best,
      Oyvind

      Reply

20. Luke Smith says

    March 13, 2017 at 10:42 pm

    I have always been curious about how blinking lights work, so reading your article and learning how a relay coil uses an electromagnet to route power to a light on and off making it blink was really cool! My dad loves electricity so he is always talking about things like this, but I have never understood what was happening. Maybe I just need to buy a relay and try to figure out how to work with it.

    Reply

    - admin says

      March 20, 2017 at 11:28 am

      Hey Luke,

      Great to hear you enjoyed the article. And yes – you should buy a relay and test it.

      Here’s another article on the relay:
      http://www.build-electronic-circuits.com/how-a-relay-works/

      Here’e how to build an electromagnet:
      http://www.build-electronic-circuits.com/build-an-electromagnet-in-5-minutes/

      Best,
      Oyvind

      Reply

21. Gavin says

    March 18, 2017 at 9:00 pm

    Hi, just wondered if you know how them flashing LED bollards work on the motorway road works. The ones I refer to are the ones that flash in a sequence without actually being connected to each other. You see them where the cones start to reduce two lanes down to one.

    Reply

    - admin says

      March 20, 2017 at 11:30 am

      I’m not familiar with them, but if there is no cable between them, there’s probably a wireless signal that keeps them in sync.

      Best,
      Oyvind

      Reply

    - Stephen says

      December 10, 2017 at 2:23 am

      It’s probably an illusion that they are connected some how. The lights blink at such a similar rate, that they just fall into sync from time to time. I have to say, dumb as it is, I like it when I see that happen. After all my years in electronics, blinking lights still make me smile. B-]
      …and just by replacing the timing resistor with 2 diodes and a pot(entiometer) you can make a dimmer or speed controller from the inverter circuit above.

      Reply

22. Ali abed says

    April 13, 2017 at 9:01 am

    Very important notice, I have small equation, who is outlet in inverter 1or 2, I think 2 that is right, thanks

    Reply

    - admin says

      April 17, 2017 at 4:58 pm

      Sorry, I don’t understand your question.

      Best,
      Oyvind

      Reply

23. julius says

    April 29, 2017 at 8:20 am

    i ve been studying in ur webpage nd i ve learnt alot bt am an amature and a hobyist inq electronics want to leav my country to meet with you nd study well cos my country is resourceless……..what do you think sir

    Reply

    - admin says

      May 2, 2017 at 2:53 pm

      Hey Julius,

      I don’t have any live courses at the moment. But I have online courses you can join here: http://ohmify.com/join/

      I wish you the best!
      Oyvind

      Reply

24. Curious says

    May 18, 2017 at 2:56 pm

    Hi

    How do i calculate my own value, what if i wanted to try other value than 9 volts. How do i calculated value for each project, ex. Charged capacitor, resistor etc.

    Is it hard ? Can you show me step by step ?

    Why do you need to use charged capacitors , why not normal one , what is the difference ?

    Thank you so much

    Adele

    Reply

25. Lulu Lucy says

    May 18, 2017 at 3:46 pm

    Why does adding of the capacitor in the last project makes the led blink slower ?

    I can ‘t think of it.

    Um… I can ‘t quite imagine what happened in the last project is it 1 run vice versa with 2 and 16 run vice versa with 8. And current from battery run to 16 and goes 3 ways 2,1,8 the one that go to led have the same state as the capacitor. If there are high current running in led ways, there are also high current running to capacitor and the capacitor are charging and when the capacitor is charging it lets the led light ( just like in project with transistor ) and when it’s fully charged then the led went off…. Then I can’ t go on what happened . Is it correct ?

    And another question.

    The one with transistor, why R2 and R3 have to be more than R1 and R4

    If I was setting values how many times does R1 and R4 have to be more than R 2 and 3. How do I calculated this?

    Thank you so much

    Adele

    Reply

26. Steve says

    July 9, 2017 at 11:05 pm

    Love the inverter blink circuit!

    What values need to be changed to use it with 12 volts dc? I have a 12v LED switch I want to blink.

    What inverter IC do you recommend using at 12v?

    Thanks for having the page…

    Reply

    - admin says

      July 10, 2017 at 3:23 pm

      Check out the HEF40106, it’s available in a version that accepts up to 15V supply voltage.

      Best,
      Oyvind

      Reply

27. Joseph Geisler says

    August 8, 2017 at 4:16 pm

    Oyvind,
    Hello,
    I am in serious need of a circuit that blinks an LED once every 15-20 seconds. It has to run on 12volt DC. I need it to not be too high a current draw (if possible) so as to not run down the vehicle’s battery. Car stays dormant for 2 weeks at a time. I do have a car alarm BUT it does not have a blinking light on the dash. I need to discourage would be thieves.
    Thank you greatly.
    PS. I build and restore hot rods and muscle cars.

    Reply

28. Am Kris wordsworth. says

    September 8, 2017 at 7:57 am

    Am Kris… Thanks i have tried one with a relay bt its noisey. Some time 2002 i had a casset with a sound level lighting led. The louder the music the brighter the led would glow… How can i make this a gain please help me out. In my new projects av tried lighting using 2 3 and 4 switches agaist one light. Am Kris from Uganda.

    Reply

29. Shipika says

    October 14, 2017 at 4:49 pm

    Please explain its working,application, advantage and disadvantages

    Reply

30. Jim F says

    October 24, 2017 at 4:58 am

    Inthe first circuit picture you said the light blinks so fast you can’t see it. How fast does it blink? How fast can you make a light blink, and how do you accomplish metering it’s blink speed?

    Reply

    - admin says

      October 26, 2017 at 4:38 pm

      It blinks as fast as it can. It’s a mechanical process that needs to take place and this will happen as fast as it’s possible. How fast depends on the relay, I’ve never measured that.

      Reply

31. Kueennga says

    October 27, 2017 at 2:41 pm

    Can germanium transistor also make a led blink?

    Reply

32. Kueennga says

    October 27, 2017 at 2:44 pm

    I need the answer for my project. Anyone..please

    Reply

33. JkinPA says

    November 3, 2017 at 12:30 am

    Hi,

    I am a newb to electronics. In these circuits you are using standard LED’s. What if I am using a flashing LED?
    I am building a model car for my daughter and want to make the turn signals blink. I have flat top 5mm LED’s that I am connecting fiber optic filament to bringing light to the different flashers. I am trying to make the circuit as small as possible (trying to fit it in the trunk). I’m figuring that I need a battery, resistor and a on-off-on micro switch (left and right lights) but want to make sure I’m not missing anything.

    Reply

    - admin says

      November 3, 2017 at 7:30 am

      If you have LEDs that are flashing “out-of-the-box”, that means they have the falshing-circuitry built in. In that case you only need what the LED requires which I am guessing is only the correct voltage. And a switch to turn it on and off, yes.

      Reply

34. Woody says

    December 20, 2017 at 8:58 pm

    Can you explain why in example 2 the capacitor is in parallel with the relay? It seems to me that it would work in series with the relay, and I can’t figure out how it works when it’s in parallel.

    If the capacitor were placed in front of the relay I imagine that it would continue to feed current into the relay for a short time after the gate to the LED has opened, thereby keeping the gate open a little bit longer.

    But in parallel I can’t see what purpose the capacitor serves. It looks to me like it just sends stored current back to the battery and doesn’t do anything to keep the relay on. Can you clarify?

    Reply

    - Woody says

      December 20, 2017 at 9:10 pm

      Never mind, I think I misunderstood how and in what direction capacitors release their charge.

      Reply

    - Bart says

      November 9, 2018 at 9:45 pm

      Hi, had a similar thought, if the capacitor is in parallel then why doesn’t the coil starts to work immediately? In the explenation you mention “After a moment, the relay coil pulls the relay into the other position.”

      Reply

      - admin says

        November 10, 2018 at 12:32 pm

        Hey Bart,
        At first when the capacitor is “empty”, the capacitor will have 0 V across its terminals. Since they are in parallel, the coil will have the same voltage across its terminal and thereby not start to work

        As the capacitor charges, the voltage increases and after a while the voltage is large enough to put the coil to work.

        Best,
        Oyvind

        Reply

35. Mohammad Reza Bayat says

    January 3, 2018 at 11:10 am

    Hi,
    In “Blinking an LED Using Relays” circuit what is the rule of the resistor R1?
    Thanks

    Reply

    - admin says

      January 8, 2018 at 11:48 am

      Hi, that ‘s to control the current through the LED. More info here: https://www.build-electronic-circuits.com/current-limiting-resistor/

      Reply

36. Tyrone says

    March 9, 2018 at 4:23 am

    Could you explain how I calculate the voltage drop at pin 7 and pin 3. Thank you. Your assistance would be greatly appreciated

    Reply

37. Aman bharti says

    April 18, 2018 at 8:29 am

    I Read How To Blink An LED With An Inverter on your website.
    Sir, i have a question ? Can this circuit works with proper connection with inverter made using transistor (not using inverter ic).

    Any can Also check on http://www.circuitspedia.com/category/led-chaser-flasher-with-4017/

    Reply

38. Yusuf says

    July 12, 2018 at 4:05 pm

    In example 2, what are the values/Nos of Q1 and Q2? In example 3, what is the value /No of U1? Thank you.

    Reply

39. Nicolas Martin says

    July 18, 2018 at 3:26 am

    Hi,
    Can I pay somebody to create one of those? :)
    I’m in Canada (Quebec), but I don’t mind paying for shipping to get the item
    I need to flash in that way : 2 sec on and 2 sec off
    I purchased controller with knob to adjust speed, but I can’t get that slow 2/2 pace
    That would control a big maximum of 10 amp on a 120v circuit.
    My email is martinn@videotron.ca

    Reply

    - admin says

      July 22, 2018 at 4:07 pm

      Hey, you can find people on upwork.com to these kinds of jobs. Good luck!
      Oyvind

      Reply

40. MOHD VAKEEL says

    August 14, 2018 at 7:12 am

    What is the purpose of residence in transistor circuit

    Reply

41. Kishan says

    November 17, 2018 at 4:07 am

    I have made a blinking led with inverter but the blink speed is too low and varies continuously. How to increase the blink speed?

    Reply

    - admin says

      November 19, 2018 at 9:00 pm

      Lower values for the capacitor and/or resistor will increase the speed.

      Best,
      Oyvind

      Reply

42. Matt H says

    November 19, 2018 at 3:55 am

    I need a 555 timer circuit that, when power is applied, will turn on an led for five minutes and then start blinking the led continuously at 1 second intervals. I was wondering if this can be done using a single 555 timer? A transistor could be used if needed.

    Thanks for your response.

    Reply

    - admin says

      November 19, 2018 at 9:03 pm

      Not that I know of. But you could use a 556 timer instead which has two 555 timers inside: Use one for having the LED on for five minutes and the other for blinking the led after

      Reply

43. faisal says

    December 2, 2018 at 5:28 pm

    what is the results of this The experience?

    Reply

44. Adrià says

    December 13, 2018 at 8:36 pm

    In the second method, the one that uses transistors, which transistors should I use? Do the leds blink at once or not? And if I want to change the blinking frequency, what should I do?

    Thanks in advance

    Reply

    - admin says

      December 14, 2018 at 11:08 pm

      The transistors can be any general purpose NPN transistor. A few choices are BC546, BC547, BC548, 2N2222, 2N3904

      Best,
      Oyvind

      Reply

45. moses says

    February 14, 2019 at 4:04 am

    pls
    How do I altenately switch on three leds of which only one is on at any point in time without microcontrollers

    Reply

    - admin says

      February 20, 2019 at 4:22 pm

      You need something with 3 or more states. You can for example modify the following circuit:
      https://www.build-electronic-circuits.com/knight-rider-light-bar-circuit/

      Reply

46. Joel says

    March 18, 2019 at 6:40 pm

    I have tried with that second method which uses transitors but i found the leds are very very dim and not blinking. Should i increase input voltage from 9v to 12v or what should i do?

    Reply

    - admin says

      March 19, 2019 at 12:15 pm

      Hi Joel,

      Increasing the voltage won’t help. It might even damage the LED.

      If the LEDs are both lit, but dim, there’s a chance it’s blinking so fast that you can’t see it. Try increasing the value of R2 and R3 – or C1 and C2.

      Increase in steps of 10x.

      Ex: if you are using 10µF for C1 and C2, try using 100 µF.

      Or if you want to increase R2 and R3: If you are using 47k now, try 470k.

      Best,
      Oyvind

      Reply

47. Rocco says

    April 3, 2019 at 3:01 am

    I have a question. With the “blinking two LEDs with transistor”, is it possible to only get one LED flash instead of two, using the same components and simply ‘cutting’ the circuit in ‘half’ so that there are only 1 of each component (to only light up one LED). Thank you

    Reply

    - admin says

      April 7, 2019 at 6:23 pm

      You can’t cut the circuit in half, no. But you can, of course, remove one of the LEDs.

      Reply

48. Sebastain says

    April 21, 2019 at 6:10 am

    Please explain why the relay does not have magnetic field to pull the switch as it is connected to the plus side and minus side of the battery directly. The capacitor is also connected across the relay coil, plus and minus sides. So how does the capacitor cause delay since the coil is also connected directly to the battery supply???

    Reply

    - admin says

      April 21, 2019 at 8:10 am

      It does get a magnetic field to begin with, and that pull disconnects the battery from the coil so that it should lose the magnetic field. But since the capacitor is connected across the coil, the capacitor keeps the coil magnetized for a bit more. Finally, the capacitor is discharged and the magnet stops pulling the pin upwards.

      Reply

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