[SOLVED] DC motor affectring input voltage mesaurment from PHMeter

Hi i have a project that use 12V DC motor and PHmeter.

PH meter is connected to the analog input of Arduino, voltage the phmeter output correspond to the measured PH value. I also need to run 12V DC motor in this project, i want to use a transistor to handle this motor, unfortunately when I run motor voltage on PH Arduino AI rise about 1V, i try to connect motor excluding transistor directly to the 12VDC power source (the same source powers Arduino on DCIN pin) in parallel to the Arduino, but effect it the same, when the motor starts voltage on arduino analog pin corresponding to the PH rise about 1V.

This is not a Arduino measurement issue because I measure voltage between Arduino AI and GND by multimeter and it actually rise about 1V, voltage between + and GNS remains constant. I connect a quick diode on a + line and 2 capitators (100µF and 100nF) between + and GND before Arduino DCIN and GND, then I run DC Motor in parallel before my filter and this not help, 1V variation still occurs.

When I replace a DC motor with a resistance load problem does not occurs, so DC motor must generate disturbances on phmeter please help :(

May be a high resistance ground connection somewhere. Are all grounds connected to a common point at the power supply? Leaving all the existing ground connections, add new ground wires from each component to the ground/negative terminal of the power supply. Measure voltages again and report.

Paul

Hi, Have you tried a 0.1uF capacitor across the terminals at the motor. Does the motor need to reverse?

If not also place a diode such as 1N4004 or 1N4007 across the motor terminals. The cathode end connected to the terminal that is connected to positive and the anode end connected to the terminal that will be negative when the pump is running.

This will suppress any noise at the source, that is the motor.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png? Showing your gnd wiring and how it is connected.

Thanks .. Tom... :)

Hi Tom
I put a 0.1uF like one photo in attachment, just like You suggested and it helps, thanks.

Now I have another problem with a relay module, You guys are familiar with distortions filtering so I will be thankful if You see this post:

thanks in advance.

Hi,
Good on the caps, can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
OPs pic.
751b141e7650d582f58e5017dacc8754b357c73f.jpg
Show how you connected the transistor and what its part number is.

Thanks… Tom… :slight_smile:

Sure :slight_smile: but a DC motor case is solved, no i have a relay module distortion issue i put my foto of a board
in this topic

i add a relay module links also

Tom I think we shoud go to there to not mix this two cases.

Hi,
We need a complete diagram. I’m sorry but this does not tell me any voltages or part numbers
8654da414aacbc6286bc1c1780303f2639ec05bd.png
Please a full diagram, including part numbers and power supply points.

Thanks… Tom… :slight_smile:
PS What do you mean by “module distortion”?

This schema is a schema of “relay module” like this one:

https://pl.aliexpress.com/item/Hot-Sale-5V-1-One-Channel-Relay-Module-Low-level-for-SCM-Household-Appliance-Control-for/32316656858.html

transistor is 2TY
all 3 resistors are 1k
“+” and “-“ on the top of schema are coil terminals
Like You see it have 3 pins at the bottom of schema.
VCC, GND and IN

VCC is connected to the 5V Arduino stabilized output, GND is GND and IN is Digital Output of Arduino.
When I turn on this module that is send “High” signal from Arduino Digital Output on “IN” pin of relay module I notice a 300mV voltage increase on Arduino Analog Input pin.

What do You think about putting 1uF capitator between “-“ and “+”coil terminals on relay module ?

Hi,
Is that diagram in my post #6 of the relay?
I need a diagram of your PCB you posted in the other thread.
09dda9fa48ee4f8ea2c635287aa05ded3638198a.png
The PCB shows DCin but only one track.

Thanks. Tom… :slight_smile:

Ok, now i get it …

pls find proper shema in atachment.

Only a “Heat Relay” and “PH” pins are connected, i disconnect all other plugs to not affect the circuit.

I supply all from stabilized 12V DC PSU.

When I turn on Digital Output to “Heat Relay” that is send “High” signal from Arduino Digital (D3) Output on “IN” pin of relay module I notice a 300mV voltage increase on Arduino Analog Input (A1) on “PH” pin.

Hi,

  • What arduino controller are you using?
  • Did you breadboard it as a prototype?
  • Did you have a working project before you went to PCB?
  • Have you got the controller working on its internal oscillator, because I see no crystal and caps for external clock.
  • Can you tell us your electronics, programming, arduino, hardware experience?

Thanks.. Tom... :)

Hi, I just see, you are using a Nano.

Where do you convert your 12V to 5V, circuit please.

When I turn on Digital Output to "Heat Relay" that is send "High" signal from Arduino Digital (D3) Output on "IN" pin of relay module I notice a 300mV voltage increase on Arduino Analog Input (A1) on "PH" pin.

What does your 5V supply measure while this is happening, I agree with Paul, your gnd circuit needs more copper and logical layout minimise voltage drops.

Tom... :)

12V line is connected to the VIN on Arduino and DC relay module i powered from 5V DC Output from Arduino. 5 V line is from Arduino stabilised output, and 12 V from stabilised DC PSU.

And i check voltage rise on +5V line too when relay module is on.

Thanks to ricky101 we figure out that problem is on Arduino Nano internal +5V stabilisation, so I use external 5V DC stabiliser to power relay coil and Digital output from Arduino to drive a relay module transistor, and it works now fine. Thank all for Your involvement.

Hi,

12V line is connected to the VIN on Arduino and DC relay module i powered from 5V DC Output from Arduino. 5 V line is from Arduino stabilised output, and 12 V from stabilised DC PSU.

Good to see you got it fixed, but if you had supplied all the information requested, including a properly labeled circuit back at post#2, that is 12 posts ago your problem would have been solved then.

Please go and add [SOLVED] to the title of this thread, because you started the thread, you can edit it.

Can you please post a copy of your new circuit, in CAD or a picture of a hand drawn circuit in jpg, png? Including your regulator etc etc.

Tom.... :)

Tom maybe it could be solved quicker but please notice that it was 2 separate problem with deferent causes, so problem no.2 definitely can’t be solved 12 post ago because then i was not aware that it exist :slight_smile:

But You are right full schematic can make everything quicker and easier.

I will upload schema and full description about a problem and how to solve it shortly.

As a footnote to porlocks problem of the voltage Rising by about 30mv.

He reported a voltage Increase when the relay was activated, which was surprising, so I duplicated part of his set up and ran some tests.

When the Nano was operated from USB power, when the relay activated (68ma) the expected voltage drop of about 30 mv was seen.

If I fed a linear regulated 5v into the Nano I got the same results.

However feeding a linear regulated 12v via the jack plug, a Rise in voltage of approx 30mv was given, confirming his problem.

Both his and my Nanos are clone boards and they use the AMS1117 regulator. ( input voltage max 15v)

Running the same test on my Genuine Arduino board with a NCP(?) 1117 ( input voltage max 20v) it worked normally, giving a small voltage drop.

So seems its a thing down to the AMS regulator, news to me, though not a charactristic I had looked for.

Also ran the same tests powering the Ardunios with a couple of the cheap digital buck and boost regulators which were more stable than the linears regulators, only dropping by about 10mv. Trouble there is a lot of debate about using that type of regulator for delicate micro devices ?

Hi, Also PCB track width acting as current limit resistors if too narrow. So not just a component problem, but a PCB quality problem.

Tom..... :)