Arduino power supply

Why does my LCD wont work if I use outside power supply?

It works well if I use the 5v pin in my Arduino.

This also happen in my sensors. The only stable power supply is only found in the arduino 5v.

How can I use outside power source and still get stable values?

Show your project schematic (wiring).

2 Likes

Are you connecting to Vin or the barrel jack?
If yes, then the voltage need to be between 7V and 12V and 9V is best.

1 Like


Just a rough sketch but that's what I use. But if i use the 5v pin in the Arduino everything looks fine. Btw, i use a breadboard for the connection of 5v, 3A power supply and the TDS sensor.

As of now, im using a cable since I am only testing the project.

Already sent a rough drawing

I will also use a pH and sensor. That is really my only problem for my project. It occurs also if I use the LCD. When I use external power supply, it does not print the texts

Your diagram should contain all components and connections. You mention e.g. a LCD but it's nowhere to be found. It should also show where the 12V goes (Vin, barrel, ...)

Assuming the 12V goes to the barrel or Vin, the voltage is reduced to 5V by a voltage regulator on the Uno. Due to lack of cooling, that voltage regulator can not provide much current; if you draw too much, it will overheat and shut down.

1 Like

no connections shown. just some unnamed lines.
Show a bit of respect to people that are trying to help you !

Most likely a missing ground / 0V line ‘somewhere ’.

Thank you for answering.

I am currently working on the TDS sensor first using.

My Arduino gets 5v from the cable. And my TDS sensor gets power from an outside power supply 5v, 3A.

As of now, that's the only component in my system which I want to resolve first.

There is only one 5v pin in the arduino. I am obliged to use an outside power source to supply my sensor.

The problems is that when i use the outside power source, the sensor connected to that do not function well. The value readings are very high and unconsistent, but when i switch and use the 5v pin from the arduino, it works fine.

How can I use an outside power source?

This also happen When I use LCD. If I use an outside power source, it doesnt lit the text.

You can use the 5V pin to power more than one sensor, as long as the maximum allowed current draw is not exceeded (TDS and pH sensors will not).

pH sensors are extremely sensitive to outside electrical disturbances, and in most cases, no other powered sensor can be present in the sample solution.

When I use LCD. If I use an outside power source, it doesnt lit the text.

That suggests a serious wiring error. For help with that, post a hand drawn schematic of the wiring, with all pins, parts and connections clearly labeled. See the "How to get the best out of this forum" post for instructions on posting.

1 Like

Is the same subject?

Don't duplicate post.

1 Like

Hi!

When I use the 5v pin from arduino, all works well. If I use an outside power supply, it wont show texts.

I am using a 5v, 3A power supply for the sensor.

did you join the GNDs ?

1 Like

Is the same subject?

Don't duplicate post.

1 Like

@sterling_2002

Your three topics on the same project have been merged. Please do not cross-post as it wastes peoples time.

1 Like

All grounds have to be connected.

1 Like

What can I do to power multiple components?
Thank you