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Flashing LED circuit using transistors on PCB – Basic Electronics Projects

September 11, 2019

Hi, welcome to Elonics. In this video I will show you how to make
a flashing LED circuit on a PCB. In the previous video I have made the same circuit on a Breadboard, and also explained how to change the flashing rate. So if you wish to do this on a breadboard, view the previous video, link to which is in the description. First, solder the pnp transistor BC557 on
the PCB with its flat surface facing towards you. Now solder the npn transistor BC547 right
beside the pnp transistor with its flat surface facing towards you, so that the pin-outs for both the transistors from the right are emitter, base and collector. Now, solder the 1K resistor between the collector of BC557 and the base of BC547. Now, solder the 22R resistor between the emitter of BC557 and the collector of BC547. And we need those extra leads to connect the capacitor as well as the power supply. Now, solder the capacitor with its positive
terminal connected to the base of BC557 and the negative terminal connected to the collector of BC 547. Now, solder LED to the PCB with its positive terminal connected to the emitter of BC547. Solder 1M resistor to the PCB such that one of its terminals is connected to the base of BC557 and the other terminal is connected to the negative terminal of LED. Now, solder the battery connectors to the
PCB, with its positive terminal connected to the emitter of BC557 and the negative terminal connected to the negative of LED. Finally connect the battery connectors to
the battery. Thanks for watching, do subscribe to this
channel and check out my other videos. If you have any queries, feel free to ask
them in the comments section below.

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  • Reply Elonics - Electronics Projects on Breadboard February 11, 2017 at 2:29 pm

    For Breadboard version of this project, view this video:

  • Reply Abdul Jalil February 11, 2017 at 3:15 pm

    great video thank you for sharing bro

  • Reply Abdul Jalil February 11, 2017 at 3:16 pm

    plz make led chaser with 555 and 4017 ic my big request

  • Reply AMIT SANA March 11, 2017 at 1:35 pm

    can I connect 5 to 6 led to thicken circuit pls tell me

  • Reply AMIT SANA March 11, 2017 at 1:36 pm

    and what is the value of capacitor in volt

  • Reply Nikhil Sawhney April 5, 2017 at 10:55 am

    Can we use bc 547b instead of bc 547?

  • Reply supriya kvs April 24, 2017 at 4:36 pm

    in the circuit you have written 10 microfarad but in the description you wrote 2.2?
    I used 10 and it didn't work.what should I do?

  • Reply Writer's अनHeard May 30, 2017 at 8:20 am

    can we have more than 1 led on PCB working? if yes then please send the link..

  • Reply Muhammad Aleem Khan June 8, 2017 at 8:22 am

    In your video the capacitor you have used is 10uF. According to your description it is 2.2uF. I used 2.2 and now it is not working.

  • Reply Aaliya Sameja June 12, 2017 at 8:46 am

    Sir, I am in first year of electronics engineering and I know the basic knowledge of transistors and other but Sir I can't make circuits on my own as you made ….so please tell me that what I do for this…….thank you

  • Reply Sridip Bhattacharya July 20, 2017 at 6:19 am

    Can we use a button cell battery for this?

  • Reply Jenith Vijayakumar August 22, 2017 at 3:34 am

    Can I add 3 leds to the circuit or is that too much? If I need to add more what should I do?

  • Reply technical nuru August 25, 2017 at 12:01 am

    Sir Youhave used 22K Resistor but it is how many watt do you useproject.

  • Reply Neil August 25, 2017 at 6:56 am

    Can you please send the simulation of the circuit? Email- [email protected] , Thanks!

  • Reply DieEneBelg August 27, 2017 at 6:42 pm

    Mine doesnt blink

  • Reply Vignesh Kannan August 30, 2017 at 3:01 pm

    Sir i give 24v so where i change and what is the value of component pls help

  • Reply cool homemade toys October 5, 2017 at 7:27 am

    How to make led bullb PCB with transfomer

  • Reply Sandip Chatterjee October 16, 2017 at 5:58 pm

    Accha nahi laga……

  • Reply John Borja October 17, 2017 at 12:33 am

    Can you please tell me how does it work? Like how do the capacitor charge and discharge? Is it the one that makes the LED blink or is it the transistors?

  • Reply saqlain 786 November 17, 2017 at 2:41 am

    can we use 1uf capacitor

  • Reply Satriya Handha December 19, 2017 at 3:28 pm

    Sir, can i use 1,5 uf capacitor to change the 2,2 uf capacitor ?

  • Reply Anirban Roy January 12, 2018 at 3:36 pm

    Your videos very helpful but can you plz make a inverter circuit….

  • Reply Amalraj Nambiar January 17, 2018 at 2:46 pm

    Sir can you plz send a circuit for a emergency lamp

  • Reply Amitava Roy February 8, 2018 at 6:53 pm

    Whwther BD 140 will work same ? Please explain how you calculated the different values of both transistor & Capacitor's ?

  • Reply Pupas 132 February 14, 2018 at 3:45 pm

    If i use the 12v dc, will it safe? and how to increase the blink, sorry my english is bad, i hope you understand

  • Reply Akshay April 11, 2018 at 2:48 am

    Can this work without soldering? Please help me, is there any way?

  • Reply Trishna Das July 26, 2018 at 12:21 pm


  • Reply Prakash Maity September 5, 2018 at 1:32 am

    what is rating of capacitor (uf & v)…??

  • Reply Daniel Allan September 14, 2018 at 5:45 pm

    How can we add a pot to change the rate/speed of the led??

  • Reply monster кот October 23, 2018 at 11:37 am

    Finally. Tnx man

  • Reply Karishma Kanaujia November 11, 2018 at 5:47 am

    Isse gayda kya hai sir plzz tell me as soon as

  • Reply sopan tonge November 16, 2018 at 2:46 am

    Kisike pass final report ki pdf ho to mujhe do yaar

  • Reply Mamad Fadaie December 16, 2018 at 10:55 pm

    Can u make an animation about this circuit and explain how capacitor charges and discharge and what voltage drop on capacitor??

  • Reply naresh dm January 24, 2019 at 3:38 pm

    How much does that cost

  • Reply Deringula Rajasekhar February 20, 2019 at 11:07 am

    Make with motor any thing

  • Reply Mahmudul Hassan February 21, 2019 at 3:19 pm

    এটাকি আমরা SCR ব্যাবহার করে করতে পারিনা?

  • Reply sagar ghatti March 7, 2019 at 2:16 pm

    something real comment about your channel. we all know that your making simple electronics circuit . but they are the back bone of basics electronics . and also your explaining method is supper and clear . my all doubt are clear in on 555 timer based project and i m thank full to you 🙂

  • Reply electronics help care March 24, 2019 at 4:13 pm

    Excellent presentation in very simple way. Thank you very much.

  • Reply Mark May 21, 2019 at 6:08 pm

    Great video, thanks for posting. I'm trying to modify this to work with a 1.5v battery, but nothing I try seems to work. Any suggestions?

  • Reply Niroshan Prasanga June 25, 2019 at 2:20 pm

    Thanks for you.

  • Reply shivani gupta July 9, 2019 at 4:19 am

    sir i have to turn led on and off for 10 ms and the size of zero pcb has to be less than 20*20 mm^2/please help

  • Reply Kenn Mossman August 24, 2019 at 8:42 am

    That is NOT a PCB

  • Reply Tommy Gillanders August 28, 2019 at 3:06 am

    Can the LED be 3ft away from PCB using longer wires?

  • Reply Raheman Mansuri August 30, 2019 at 7:02 pm

    Very nice

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