Would PWM controlled fan effect Arduinos on the same circuit ?

Thread Starter

CrustyS

Joined May 20, 2019
13
In a nutshell.. I have a 12V 6A switching power supply feeding a 18" fan @ 13kHz and max 60% duty drawing 4A peak, duty is determined by temperature sensor/arduino/MOSFET using separate power supply at the moment (battery).

My intent is to simplify the power supply by using a buck converter to supply the arduino from the same switching supply as the fan.

Should I expect to fit some filtration before the buck converter ?
 

LowQCab

Joined Nov 6, 2012
1,286
Yes.
The Power-Supply can never be "too-clean".
From the 12-Volt SMPS,
install a Resistor that will result in a ~2-Volt, Voltage-Drop under
maximum-Load conditions.

Follow the Resistor with the largest practical
Capacitor that will physically fit your application.
It's not really necessary to exceed ~1000uf,
470uf will work fine,
stay above 100uf-minimum.

Add a 100nf Ceramic-Capacitor in parallel with the Electrolytic-Input-Capacitor.

Then go into a Linear-Regulator,
with an Output-Capacitor equal to, or exceeding,
the recommended Output-Capacitance in the Regulator Data-Sheet.
Also add a 100nf Ceramic-Capacitor to the Regulator Output.

The Ground connection to the Regulator MUST originate directly from
the Power-Supply Ground-Output.

If the Regulator and Capacitors are not on the same Board as the Micro-Processor
tightly twist any open Wiring between the two,
or use small Shielded-Cable.

With this arrangement in place, the only Noise will be from RFI in the Air.
.
.
.
 

djsfantasi

Joined Apr 11, 2010
7,911
The Arduino has a fairly robust voltage regulator so NO.
You don’t state the actual output voltage of your power supply nor how stable it is, so while I agree with @SamR , to be clear I would include your buck converter in case you read that it wasn’t required for the Arduino.

Are you aware that there are multiple power connection methods possible to the Arduino? I’m assuming that you’re using Vin… or the power jack.

I would set the buck converter to 9VDC. Then, power the Arduino as above.

9VDC is a good voltage to input to the Arduino onboard voltage regulator. While the input voltage range is 5-12VDC, 5 is too low for the VR and 12 is at the top of the range, causing the VR to work too hard.
 

MB107

Joined Jul 24, 2016
154
I am doing that with a much higher power 60A 12V fan. I am using a 30A 12V power supply connected directly to the fan and Arduino. I have no filtering. It works but I probably should have some filtering.
 

Thread Starter

CrustyS

Joined May 20, 2019
13
You don’t state the actual output voltage of your power supply nor how stable it is, so while I agree with @SamR , to be clear I would include your buck converter in case you read that it wasn’t required for the Arduino.

Are you aware that there are multiple power connection methods possible to the Arduino? I’m assuming that you’re using Vin… or the power jack.

I would set the buck converter to 9VDC. Then, power the Arduino as above.

9VDC is a good voltage to input to the Arduino onboard voltage regulator. While the input voltage range is 5-12VDC, 5 is too low for the VR and 12 is at the top of the range, causing the VR to work too hard.
The buck converter is LM2596 based with specification :

Description:
Conversion efficiency of 92% (maximum)
Input voltage 5V ~ 35V
Output voltage 1.25V ~ 35V
Output current 3A (max)
Output ripple <30mV
Load regulation: 0 0.5%
Voltage regulation: 2.5%
Switching frequency 65KHz

I was intending to set the output at 7-8V to supply extra voltage to the 433MHz transmitter in the circuit to help with its range. I would be using Vin for the Arduino pro mini's (5V 16MHz clones) I use for the rest of the sensors.
 
Last edited:

Thread Starter

CrustyS

Joined May 20, 2019
13
Yes.
The Power-Supply can never be "too-clean".
From the 12-Volt SMPS,
install a Resistor that will result in a ~2-Volt, Voltage-Drop under
maximum-Load conditions.

Follow the Resistor with the largest practical
Capacitor that will physically fit your application.
It's not really necessary to exceed ~1000uf,
470uf will work fine,
stay above 100uf-minimum.

Add a 100nf Ceramic-Capacitor in parallel with the Electrolytic-Input-Capacitor.

Then go into a Linear-Regulator,
with an Output-Capacitor equal to, or exceeding,
the recommended Output-Capacitance in the Regulator Data-Sheet.
Also add a 100nf Ceramic-Capacitor to the Regulator Output.

The Ground connection to the Regulator MUST originate directly from
the Power-Supply Ground-Output.

If the Regulator and Capacitors are not on the same Board as the Micro-Processor
tightly twist any open Wiring between the two,
or use small Shielded-Cable.

With this arrangement in place, the only Noise will be from RFI in the Air.
.
.
.
Thank you for the detailed instructions, I will try these if I run into problems.
 

djsfantasi

Joined Apr 11, 2010
7,911
Yes.
The Power-Supply can never be "too-clean".
From the 12-Volt SMPS,
install a Resistor that will result in a ~2-Volt, Voltage-Drop under
maximum-Load conditions.

Follow the Resistor with the largest practical
Capacitor that will physically fit your application.
It's not really necessary to exceed ~1000uf,
470uf will work fine,
stay above 100uf-minimum.

Add a 100nf Ceramic-Capacitor in parallel with the Electrolytic-Input-Capacitor.

Then go into a Linear-Regulator,
with an Output-Capacitor equal to, or exceeding,
the recommended Output-Capacitance in the Regulator Data-Sheet.
Also add a 100nf Ceramic-Capacitor to the Regulator Output.

The Ground connection to the Regulator MUST originate directly from
the Power-Supply Ground-Output.

If the Regulator and Capacitors are not on the same Board as the Micro-Processor
tightly twist any open Wiring between the two,
or use small Shielded-Cable.

With this arrangement in place, the only Noise will be from RFI in the Air.
.
.
.
Great detail. But…

An Arduino has the regulator and filter capacities, et al onboard. So many of the components you describe are unnecessary. The TS just needs a 9V input to the board. Could be 5-12V, but note their (Arduino) are wall wart for the Arduino provides 9V. At lower voltages there might not be enough headroom for the onboard VR. At higher than 9V, the onboard VR will heat up and may prematurely fail.

The Arduino CAN be powered directly with a well-filtered 5V supply. But unless you have a pre-existing source, why waste money duplicating onboard resources?
 

LowQCab

Joined Nov 6, 2012
1,286
I have to admit that I do not follow current Micro-Processor Technology,
it changes by the hour, and I personally don't find much use for them
and so I have not "taken-the-dive" on the steep learning curve.

But whether or not a particular Board has a built-in Regulator,
it's not a bad plan to spread-out the Heat associated with
reducing and filtering the Power-Supply-Voltage,
especially when working with SMD-Designs,
which quite commonly have Heat-Dissipation issues that must be considered.

If some of the Heat can be moved off the Board,
I'd say it might be a good idea, (depending on the circumstances of course).
.
.
.
 

djsfantasi

Joined Apr 11, 2010
7,911
There seems to be some confusion regarding microprocessor solutions. It may because microprocessor is a general term, that encompasses several different technologies…

There are different types of this technology. From bare metal to complete systems. The Arduino is a complete system, based on an open source design. As such, you don’t design a “board” when using this technology unless you want to either make a custom design or like to duplicate the work of others.

Microprocessor technology runs the gamut of a single MPU chip like the PIC to complete systems like the Arduino (and others) to powerful computers like the Raspberry PI.

Heat dissipation issues on an Arduino are resolved by the design and the specificationsfor power, GPIO current limitations, etc…

That’s why I recommended using a 9V source. The Arduino is rated at a max supply voltage of 12V, but how often do we design to the max of any parameter?

The low end of an Arduino voltage is achievable by bypassing the onboard voltage regulator. The design includes supplying 5V (or 3.3V) directly or a higher supply using the onboard regulator.

There are other microprocessor platforms and these comments won’t apply. A popular platform is the PIC series. But you DO need to design the power supply or regulation as it isn’t included when you purchase a PIC. Nor is there a built-in boot loader, nor is hardware initialization pre-programmed.

Most serious designers go the bare metal approach. Some even dismiss the Arduino as a toy. They dismiss the modular MCU and “shield” or peripheral approach as child’s play. But for a quick project, prototyping and ease in programming, the Arduino has its place.

One last comment. The modular approach is used in most software, allowing quick development of very complex systems. It started with the concept of “reusable code”. Most of the software in general use is based on this theory and likely wouldn’t exist if programmers didn’t have such “child’s play”. While you may like assembler, imagine if the internet only used assembly.

I hope someone finds this useful.
 

SamR

Joined Mar 19, 2019
3,601
The Arduino comes in multiple configurations now. Uno, Mega, Nano, to just name a few. The big difference is the I/O Pin count. All come not only with the microprocessor of which there are quite a few versions now, but also with the frequency crystal, power supply, DAC, and various communication modes. It is a pretty all-comprehensive package and considered to be a "development" microprocessor board for those with little or no electronic background. In particular for artists and designers. Price wise, it is hard to compete against if you were to build it from scratch.
 

MB107

Joined Jul 24, 2016
154
The Arduino comes in multiple configurations now. Uno, Mega, Nano, to just name a few. The big difference is the I/O Pin count. All come not only with the microprocessor of which there are quite a few versions now, but also with the frequency crystal, power supply, DAC, and various communication modes. It is a pretty all-comprehensive package and considered to be a "development" microprocessor board for those with little or no electronic background. In particular for artists and designers. Price wise, it is hard to compete against if you were to build it from scratch.
I'm using the Yourdurino RoboRed. The RoboRed is good for 20V input. I chose that board because, it will be used in an automotive application which is really 14V.
 

Thread Starter

CrustyS

Joined May 20, 2019
13
Thanks for everyones help and suggestions I am building now with a common 12V regulated power supply and a buck converter capable of supplying sufficient power to the two Arduinos
 
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