A few of you requested to know how I was driving the LEDs. Here is a simple schematic. The first one shows you how you can drive them with a P Channel MOSFET along with an NPN transistor and the second one shows you how to do it with a single NPN transistor. On the flash light, I have three sets of LEDs. 18, 12, and 7. Each set controlled by a separate driver. The VCC here is the LiPo battery output which can be in between 3.6 to 4.2V. The control INPUT can be connected to an Arduino. In my case, it was the Adafruit Trinket M0. You can use a 3V3 version of the Arduino mini instead. Hope this helps!

Minneapolis, Minnesota



  • @mohitbhoite 3:17 AM Jan 13, 2019

    #particle #embeddedsystems #raspberrypi #cad #electronics #hardware #programming #diy #3dprinting #microcontroller #make #arduino #arduinoproject #drone #iot #circuits #robotics #robot #adafruit #sparkfun #soldering #electricalengineering #freeform #computerscience #engineering #led #sculptures #makersgonnamake #mechanicalengineering

  • @richard.escobar.reyes 3:20 AM Jan 13, 2019

    Que lindo! Si puedes seguir haciendo de estos circuitos. Porfavor. Saludos

  • @pr4nit 3:23 AM Jan 13, 2019

    Can you tell me the difference between high side load and low side load?

  • @mohitbhoite 3:24 AM Jan 13, 2019

    @richard.escobar.reyes gracias. Lo haré.

  • @3lectr1c 3:24 AM Jan 13, 2019


  • @arnavbansal95 3:25 AM Jan 13, 2019

    I think a Darlington Pair would be a better choice, something like TIP122 which can bear high power.

  • @bgarbz 3:25 AM Jan 13, 2019

    High side switch!

  • @mohitbhoite 3:26 AM Jan 13, 2019

    @pr4nit I think google will do a better job of that. Schematic one is a high side switch and the second one is low side.

  • @mohitbhoite 3:29 AM Jan 13, 2019

    @arnavbansal95 yes, better suited for higher power application.

  • @mohit5611 3:45 AM Jan 13, 2019

    Thanku so much

  • @pr4nit 3:53 AM Jan 13, 2019

    @mohitbhoite ho ho.. Mhanun ch vicharla ki..ek schematic madhe high side, dusrya madhe low side. Why so

  • @richard.escobar.reyes 4:18 AM Jan 13, 2019

    @mohitbhoite muchas gracias. Saludos

  • @jason.iceman 4:19 AM Jan 13, 2019

    Hey pal, got a light?

  • @victorsatiro 4:20 AM Jan 13, 2019

    @mohitbhoite you using Eagle for your projects?! You using PRO version or student's?!

  • @jesal_1911 4:21 AM Jan 13, 2019

    @mohitbhoite you can do charlie multiplexing in this project..!

  • @daft_niel 4:48 AM Jan 13, 2019

    Thank you!

  • @aj_mu2.5 4:52 AM Jan 13, 2019


  • @m.ea14 5:20 AM Jan 13, 2019

    Bro you said you use a MOSFET transistor but the circuit shows that the transistor is a bjt NPN ?!!

  • @mohitbhoite 5:42 AM Jan 13, 2019

    @m.ea14 yes, in the first schematic the p channel mosfet is driven by a NPN transistor

  • @fakhrurraziputra 8:31 AM Jan 13, 2019

    Where do I get the Pro version of the eagle?

  • @peter_default 8:58 AM Jan 13, 2019

    Was your decision of using these transistors or the MOSFET driven by what you have in the lab?

  • @f0cks_ 9:13 AM Jan 13, 2019

    Hello! What is the reason to use bipolar technology to drive a Mos and not an other mos? Same question for lowside, why do you use a npn and not a nmos? Is it for CEM considerations? (Or price, or stock reason?)

  • @crowstudio 9:16 AM Jan 13, 2019

    Why did you not use the NPN setup, is it because of the power consumption? I got confused why you posted two setups! 😉

  • @jessexy_baker 11:48 AM Jan 13, 2019

    I wish they taught me this in school 😒

  • @tshashmi 12:04 PM Jan 13, 2019

    Thank you. What is the constant current value achieved in these schematics

  • @mohitbhoite 3:57 PM Jan 13, 2019

    @peter_default yes!

  • @mohitbhoite 3:58 PM Jan 13, 2019

    @crowstudio based on something that I had laying around. More importantly, I made a design error in the beginning which made me improvise and use a high side switch instead of a simple NPN transistor setup.

  • @crowstudio 4:05 PM Jan 13, 2019

    @mohitbhoite Aha, fair enough! 😁

  • @mohitbhoite 9:27 PM Jan 13, 2019

    @tshashmi each LED is pulling around 40mA peak. I’m PWMing the input to control the brightness.

  • @mohitbhoite 9:27 PM Jan 13, 2019

    @f0cks_ there are multiple ways to do this. I used what I had at hand without special ordering something.

  • @mohitbhoite 9:28 PM Jan 13, 2019

    @fakhrurraziputra you can buy their subscription online

  • @mohitbhoite 9:29 PM Jan 13, 2019

    @jesal_1911 no just running them in parallel in three groups.

  • @f0cks_ 9:30 PM Jan 13, 2019

    @mohitbhoite so it will remain a mystery 😄 Thanks for your answer! 👍🏻

  • @mohitbhoite 9:31 PM Jan 13, 2019

    @f0cks_ look up using MOSFET as switches, you’ll get plenty of ideas. I also recommend the book Art of Electronics

  • @otraastronauta 1:13 PM Jan 14, 2019

    Which Is the "imput"?

  • @hoseinezati66 12:10 PM Jan 15, 2019


  • @stanley22n 7:26 PM Jan 15, 2019

    @pr4nit load on the collector side does not affect base-emmiter voltage if I remember well.