# Power supply issue **URL:** \ **Category:** General Guidance\ **Created:** [March 22, 2026, 8:02am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501 "2026-03-22T08:02:43Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![dhimansarkerady](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/dhimansarkerady/32/1263434_2.png) [@dhimansarkerady](https://forum.arduino.cc/u/dhimansarkerady)\ **Post date:** [March 22, 2026, 8:02am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/1 "2026-03-22T08:02:43Z")
I am building a automatic water supply project. But, I am facing problem with Power supply. The noise is making Arduino hang and reset. I have 1. Ultrasonic sensor- 2x, 2. Relay- 1x, 3. Water level sensor - 1x, 4. LCD display 16x2 - 1x, 5. Active buzzer - 1x, 6. Passive buzzer - 1x, 7. LED(5mm) - 5x, 8. Arduino UNO - 2x, For power supply 1. 5V mobile charger - 3x, (500mA, 700mA, 1A) 2. 12V charger - 2x, (5A, 1A) 3. Capacitor - 5x, (470uF) 4. Capacitor - 2x, (1000uF). How should i supply the power? Whare should i place the capacitor? What is the ground loop? How do i create common ground? ---
**Author:** ![PaulRB](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paulrb/32/216330_2.png) [@PaulRB](https://forum.arduino.cc/u/PaulRB)\ **Post date:** [March 22, 2026, 8:29am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/2 "2026-03-22T08:29:37Z")
> [@dhimansarkerady](#): > > I have You may find that you also need some valve or pump. > [@dhimansarkerady](#): > > How should i supply the power? You can power the Uno from 12V provided that your relay is a 12V relay. But if you use a 5V relay, there is danger of burning the Uno's regulator because it will need to supply 5V to the relay, which will require a high current. In that case, you must use 2x power supplies (5V + 12V) or get a MOSFET module to replace the relay. ---
**Author:** ![PaulRB](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paulrb/32/216330_2.png) [@PaulRB](https://forum.arduino.cc/u/PaulRB)\ **Post date:** [March 22, 2026, 8:34am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/3 "2026-03-22T08:34:27Z")
> [@dhimansarkerady](#): > > The noise is making Arduino hang and reset. This happens when? I can't see any components in your list that would cause significant noise. > [@dhimansarkerady](#): > > Whare should i place the capacitor? I don't see a need for it. > [@dhimansarkerady](#): > > How do i create common ground? Connect the ground wires. ---
**Author:** ![build\_1971](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/build_1971/32/689930_2.png) [@build\_1971](https://forum.arduino.cc/u/build_1971)\ **Post date:** [March 22, 2026, 8:35am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/4 "2026-03-22T08:35:21Z")
Why do you have so many power supplies involved (5 in total...)? How is tgat all connected? ---
**Author:** ![dhimansarkerady](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/dhimansarkerady/32/1263434_2.png) [@dhimansarkerady](https://forum.arduino.cc/u/dhimansarkerady)\ **Post date:** [March 22, 2026, 8:36am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/5 "2026-03-22T08:36:32Z")
Yes, I am also using a motor(3.7-6v) and powering it with a separate dc 12v battery(Trough buck converter). I am using 5V relay through 5v mobile charger. ---
**Author:** ![PaulRB](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paulrb/32/216330_2.png) [@PaulRB](https://forum.arduino.cc/u/PaulRB)\ **Post date:** [March 22, 2026, 8:36am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/6 "2026-03-22T08:36:54Z")
> [@build\_1971](#): > > so many power supplies involved I suspect this is an inventory of components that @dhimansarkerady has available, and may not all be required. ---
**Author:** ![PaulRB](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paulrb/32/216330_2.png) [@PaulRB](https://forum.arduino.cc/u/PaulRB)\ **Post date:** [March 22, 2026, 8:41am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/7 "2026-03-22T08:41:40Z")
> [@dhimansarkerady](#): > > using a motor(3.7-6v) and powering it with a separate dc 12v battery(Trough buck converter) What is the motor for? Did you mean to say pump? If your pump is 5V compatible, why are you using 12V battery and buck converter? Why not use another 5V PSU? I do not think we can help you fix the hanging problem without knowing the specifications of these components and how they are connected. Please post your schematic diagram. ---
**Author:** ![dhimansarkerady](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/dhimansarkerady/32/1263434_2.png) [@dhimansarkerady](https://forum.arduino.cc/u/dhimansarkerady)\ **Post date:** [March 22, 2026, 8:41am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/8 "2026-03-22T08:41:49Z")
No, I am using all the components. ![WhatsApp Image 2026-03-22 at 2.40.20 PM](https://europe1.discourse-cdn.com/arduino/original/4X/3/8/6/386debc84accf3460c41e226f106ff61fa8d0246.jpeg) ![WhatsApp Image 2026-03-22 at 2.39.36 PM (1)](https://europe1.discourse-cdn.com/arduino/original/4X/8/c/e/8ceea8246a58632b2094e2c0dce4fd49b2051902.jpeg) ![WhatsApp Image 2026-03-22 at 2.39.36 PM](https://europe1.discourse-cdn.com/arduino/original/4X/1/1/6/116e1e1be9886100ad33e7d1654042cdb488a9ec.jpeg) ---
**Author:** ![PaulRB](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paulrb/32/216330_2.png) [@PaulRB](https://forum.arduino.cc/u/PaulRB)\ **Post date:** [March 22, 2026, 8:48am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/9 "2026-03-22T08:48:35Z")
Thanks for posting those photos. The situation is now very clear, and the malfunction was inevitable. Disconnect everything and start over. Use only one Arduino Use 2x 5V PSU. One for the Arduino and one for the pump and relay. Use a flyback diode. ---
**Author:** ![dhimansarkerady](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/dhimansarkerady/32/1263434_2.png) [@dhimansarkerady](https://forum.arduino.cc/u/dhimansarkerady)\ **Post date:** [March 22, 2026, 9:04am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/10 "2026-03-22T09:04:09Z")
![WhatsApp Image 2026-03-22 at 3.00.54 PM](https://europe1.discourse-cdn.com/arduino/original/4X/a/7/2/a72884824518ae2a65ec1052a6fd132828fd39ae.jpeg) This is the diagram. (Maybe the picture is blur. I am sorry for that.) ---
**Author:** ![dhimansarkerady](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/dhimansarkerady/32/1263434_2.png) [@dhimansarkerady](https://forum.arduino.cc/u/dhimansarkerady)\ **Post date:** [March 22, 2026, 9:09am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/11 "2026-03-22T09:09:03Z")
![WhatsApp Image 2026-03-22 at 3.00.54 PM](https://europe1.discourse-cdn.com/arduino/original/4X/a/7/2/a72884824518ae2a65ec1052a6fd132828fd39ae.jpeg) This is the diagram. (Maybe the picture is blur. I am sorry for that.) > [@PaulRB](#): > > Use only one Arduino Arduino Uno smd hasn't enough pwm pin for all the module. That's why i have used 2 arduinos. ![WhatsApp Image 2026-03-22 at 3.05.10 PM](https://europe1.discourse-cdn.com/arduino/original/4X/9/e/3/9e3a8060a0363062f4d384570426ec8895f49056.jpeg) > [@PaulRB](#): > > Use only one Arduino Arduino uno smd hasn't enough pwm pin for all the modules. Thats why i have used 2 arduino uno. ![WhatsApp Image 2026-03-22 at 3.05.10 PM](https://europe1.discourse-cdn.com/arduino/original/4X/9/e/3/9e3a8060a0363062f4d384570426ec8895f49056.jpeg) ---
**Author:** ![dhimansarkerady](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/dhimansarkerady/32/1263434_2.png) [@dhimansarkerady](https://forum.arduino.cc/u/dhimansarkerady)\ **Post date:** [March 22, 2026, 9:13am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/12 "2026-03-22T09:13:19Z")
> [@PaulRB](#): > > Use a flyback diode. The relay has already a built in flyback diode. Should i use one more? ![WhatsApp Image 2026-03-22 at 3.10.18 PM](https://europe1.discourse-cdn.com/arduino/original/4X/6/9/9/699804e0fd1ea109ed9b40a2987f457e324e4a5c.jpeg) Please check diagram the relay and motor have separate power supply. Does it need the flyback diode? ![WhatsApp Image 2026-03-22 at 3.00.54 PM](https://europe1.discourse-cdn.com/arduino/original/4X/a/7/2/a72884824518ae2a65ec1052a6fd132828fd39ae.jpeg) ---
**Author:** ![PaulRB](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paulrb/32/216330_2.png) [@PaulRB](https://forum.arduino.cc/u/PaulRB)\ **Post date:** [March 22, 2026, 9:50am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/13 "2026-03-22T09:50:29Z")
> [@dhimansarkerady](#): > > Arduino Uno smd hasn't enough pwm pin for all the module Which modules require PWM pins? I do not see any that require PWM. ---
**Author:** ![PaulRB](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/paulrb/32/216330_2.png) [@PaulRB](https://forum.arduino.cc/u/PaulRB)\ **Post date:** [March 22, 2026, 9:59am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/14 "2026-03-22T09:59:51Z")
> [@dhimansarkerady](#): > > Does it need the flyback diode? Your diagrams are clearly incomplete, many component's terminals are not connected, so it is difficult to answer that question accurately. The diode you indicated with an arrow is the flyback diode for the relay's coil. The flyback diode I mentioned is for the pump. Assuming your diagram is accurate in this respect, a flyback diode for the pump may not be required because the pump has it's own power supply which does not have a common ground with the rest of the circuit. However, because of your hanging problem, it may be worth testing to see if a flyback diode for the pump is helpful. I cannot say this for sure because your description of the hanging problem is also incomplete. ---
**Author:** ![jim-p](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/jim-p/32/922840_2.png) [@jim-p](https://forum.arduino.cc/u/jim-p)\ **Post date:** [March 22, 2026, 11:42am UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/15 "2026-03-22T11:42:14Z")
See this topic > [@Can't run the program when I have both a soil moisture and a water pump connected to arduino uno](https://forum.arduino.cc/t/cant-run-the-program-when-i-have-both-a-soil-moisture-and-a-water-pump-connected-to-arduino-uno/1253110/15): > > The problem is the pump. You are not the first person to have interference problems with that particular pump. You will need to buy a 1N4002 diode and a 0.1uF ceramic capacitor. Connect everything like this: ---
**Author:** ![GolamMostafa](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/golammostafa/32/239011_2.png) [@GolamMostafa](https://forum.arduino.cc/u/GolamMostafa)\ **Post date:** [March 22, 2026, 12:12pm UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/16 "2026-03-22T12:12:39Z")
> [@Can't run the program when I have both a soil moisture and a water pump connected to arduino uno](https://forum.arduino.cc/t/cant-run-the-program-when-i-have-both-a-soil-moisture-and-a-water-pump-connected-to-arduino-uno/1253110/15): > > and a 0.1uF ceramic capacitor. Is it needed to specify the voltage rating of the capa? ---
**Author:** ![jim-p](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/jim-p/32/922840_2.png) [@jim-p](https://forum.arduino.cc/u/jim-p)\ **Post date:** [March 22, 2026, 12:46pm UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/17 "2026-03-22T12:46:27Z")
> [@GolamMostafa](#): > > Is it needed to specify the voltage rating of the capa? No. ---
**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\ **Post date:** [September 18, 2026, 12:46pm UTC](https://forum.arduino.cc/t/power-supply-issue/1436501/18 "2026-09-18T12:46:34Z")
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