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Topic: LCD very dim (wiring issue?) (Read 232 times) previous topic - next topic

drum_computer

Sep 16, 2020, 11:39 am Last Edit: Sep 16, 2020, 02:08 pm by drum_computer
Hi! I'm almost done with my first arduino project. Arduino Midi - Usb host. Hovewer, I'm a complete noob when it comes to hardware side of things. I just connect everything based on various examples, snippets (and ocassionaly even datasheets!) that I find online.

Here's how everything looks right now:

My problem is that when I connect everything together my 20x4 lcd display becomes very dim.
I've seen on the forum that dim lcd usually fixed with adding resistor to contrast pin, which makes it even worse for me, or that screen redraw code is put in the loop so it's constantly clearing/printing it's content - also not the case in my situation.

When I assembled this thing first, I connected my four buttons to the right of the lcd at which point it became dim (was fine before that). Knowing not what to do in this situation I decided to move buttons to another breadboard and surprisingly it worked.

However later in the project I decided to add an external EEPROM chip (above/to the left of the buttons) and again my lcd became very dim.

What surprises me is that the whole thing is powered with 9v power adapter connected to arduino.

Any thoughts? 

AJLElectronics

What surprises me is that the whole thing is powered with 9v power adapter connected to arduino.

Any thoughts? 
There you are.

AJLElectronics

#2
Sep 16, 2020, 12:28 pm Last Edit: Sep 16, 2020, 12:29 pm by AJLElectronics
The Arduino is a 5V device and should be fed to the 5V input (it isn't an output) on the board. You then need a power supply suitable for the Voltages expected by your other peripherals. If everything is 5V then a decent 5V plug in power supply will do fine. If you need 12V for instance, then you would use a switching converter from 12V to 5V. The only exception is when dealing with low level audio or RF, when a linear regulator might be a more sensible choice.

Can we have a circuit diagram please? Pretty Fritzing pictures do not fall under that title by the way.

AJLElectronics

By way of further explanation, the barrel connector on your Arduino supplies a surface mount regulator. That regulator has no heatsink and is purely intended to aid a quick demo with the on board LEDS.  If you try to pull any more current from it, it gets hot and starts to fold back in order to protect itself. Further abuse will result in it hopefully shutting down, or maybe letting out the magic smoke if you are unlucky.

drum_computer

Tbh the external power adapter is the last place that I would search for a problem :)

However, I just tried to disconnect it and connect my usb wire to a charging port of my anker usb 3.0 hub
according to spec it provides 5v with up to 2A of current. However it didn't fix the lcd problem, moreover my midi controller (korg nanocontrol) stopped working as it draws power from usbhost shield.

Quote
Can we have a circuit diagram please? Pretty Fritzing pictures do not fall under that title by the way.
I'm very sorry but I have no clue how to make it.

AJLElectronics

#5
Sep 16, 2020, 12:53 pm Last Edit: Sep 16, 2020, 12:54 pm by AJLElectronics
Tbh the external power adapter is the last place that I would search for a problem :)
Well now you would. (hopefully)

I'm very sorry but I have no clue how to make it.
You get a piece of paper and a pencil, draw your circuit and then take a photo of it.  Not being clairvoyant, it is difficult to help you without all the information.

vilmabergmann

I'm very sorry but I have no clue how to make it.
I just happened across this thread with link to youtube.




TomGeorge

Everything runs on smoke, let the smoke out, it stops running....


TomGeorge

Hi,
Use the DMM to monitor the 5V line as you troubleshoot your problem.

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

PaulRB

#10
Sep 16, 2020, 01:49 pm Last Edit: Sep 16, 2020, 01:52 pm by PaulRB
Quote
Here's how everything looks right now:
When I clicked on one of your photos to take a close look, I saw a page full of ads for pornography and gambling. Fortunately, I am a adult,  but some other forum members are not. You should modify your post and remove those before one of the forum moderators sees them, or worse, a young or vulnerable forum member sees them.

By all means post photos of your circuit, but do that as described in the forum guide on the sticky post at the top of each forum section. There is no need to use photo hosting sites here.

drum_computer

When I clicked on one of your photos to take a close look, I saw a page full of ads for pornography and gambling. Fortunately, I am a adult,  but some other forum members are not. You should modify your post and remove those before one of the forum moderators sees them, or worse, a young or vulnerable forum member sees them.

By all means post photos of your circuit, but do that as described in the forum guide on the sticky post at the top of each forum section. There is no need to use photo hosting sites here.
Yikes! Probably didn't see it because I'm using adblock. My bad. Links removed. Also I was experimenting with wires that looked cheesy to me and replaced couple of them totally fixed everything.

So, cased closed, I guess. Thanks everyone for your help!

MarkT

If you were using pre-made breadboard hookup wires with dupont connectors you'll find some
makes are unable to handle anything but signals - the actual copper wires are ultra-thin inside,
and the crimping is thus unreliable as there's not enough wire to crush inside the crimp.

Even the best kinds aren't super high current.

I use 0.6mm diameter single core hookup wire and make up my own hook-up wires, these have
about 0.06 ohms per metre, which will usually be fine upto 1A or so in most circumstances.

If you have some random wire, strip the end off and measure the diameter of the copper, then
you can lookup / calculate its current limitation.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Paul__B

If you were using pre-made breadboard hookup wires with Dupont connectors you'll find some
makes are unable to handle anything but signals - the actual copper wires are ultra-thin inside,
and the crimping is thus unreliable as there's not enough wire to crush inside the crimp.
And that assumes they are in fact, copper!  :smiley-roll:

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