Noise for module distance measure srf055

[haohaodk46]

Hi Everyone,
I got issue with SRF05 distance measurment module . If I use batterry supply then the module measured distance correct but If I use a pulse power ( 220VAC => 24VDC ) then the module got noise and can't get correct distance
Maybe power supply is noise lead to IC OPAM LM324 is not correct work
The everyone can be recommend a filter power for srf05 module to It can work correctly ?

 

[KlausST]

Hi,

Without a schematic you can´t expect a detailed answer.
So post your schematic, at least a draft.

***
Noise: It could be
* audible noise
* ultrasonic acoustic noise (inaudible)
* electrical (wired) common mode noise
* electrical supply voltage ripple
* and so on.

And every one of the above asks for a different solution.

Thus the ususal way is to analyze the source of noise and it´s behaviour (amplitude, frequency bandwidth...)
Additionally one needs your application´s specicifcations about: voltage, current and frequency range of interest of the node you want to insert the filter.

Besides hardware filter you should consider to use an (additional) software filter.

Klaus

 

[FvM]

SRF05 has 5V supply if I remember right. How do you connect it to 24V power? Schematic would clarify.

 

[danadakk]

Picture of your prototype wiring ......

Regards, Dana.

 

[D.A.(Tony)Stewart]

Your problem is 24V instead of 5V.

 

[haohaodk46]

SRF05 has 5V supply if I remember right. How do you connect it to 24V power? Schematic would clarify.

SRF05 has 5V supply if I remember right. How do you connect it to 24V power? Schematic would clarify.

No I mean that if I use a pulse power supply 220VA-24VDC via a buck circuit using LM2576 to 5V output then It is noised
This is buck circuit i used

And this power supply that cause noise

--- Updated Mar 31, 2024 ---

Hi,

Without a schematic you can´t expect a detailed answer.
So post your schematic, at least a draft.

***
Noise: It could be
* audible noise
* ultrasonic acoustic noise (inaudible)
* electrical (wired) common mode noise
* electrical supply voltage ripple
* and so on.

And every one of the above asks for a different solution.

Thus the ususal way is to analyze the source of noise and it´s behaviour (amplitude, frequency bandwidth...)
Additionally one needs your application´s specicifcations about: voltage, current and frequency range of interest of the node you want to insert the filter.

Besides hardware filter you should consider to use an (additional) software filter.

Klaus

For * electrical supply voltage ripple . This noise . Do you have solution for this

 

[D.A.(Tony)Stewart]

You must use a linear regulator to prevent noise or a very steep notch LPF filter especially near 40 kHz pulses.

All SMPS designs may have too much noise for this.

So modify to ~ 7.5V and add a 5V LDO circuit.

 

[KlausST]

You must use a linear regulator to prevent noise

it depends.
I often use SMPS with quite simple filters (often just capacitors) and still got stable readings on 16 bit ADCs (according datasheet specification).

PCB layout, parts placement, current, andother things play a role...

Klaus

 

[D.A.(Tony)Stewart]

I'll let @KlausST solve your measure noise problem his way.

 

[haohaodk46]

it depends.
I often use SMPS with quite simple filters (often just capacitors) and still got stable readings on 16 bit ADCs (according datasheet specification).

PCB layout, parts placement, current, andother things play a role...

Klaus

I think that module srf05 is using OPAM is sensitive with voltage more than ADC .

 

[KlausST]

I think that module srf05 is using OPAM is sensitive with voltage more than ADC .

"I think"means guessing.
But for me designing electronics has nothing to do with guessing. It´s all physics and math.

Thus I need facts like:
* a complete wiring diagram 1) with the 24V SMPS 2) without the 24V SMPS (to see the difference)
* a scope picture of the power supply noise, and the distance noise (if available)
* photos of the whole circuit (100kBytes each should be suffcient)
* what the results look like 1) with the 24V SMPS 2) without the 24V SMPS (to see the difference)
* datasheets
* .. all that information relates to the noise (maybe you did use a microcontroller and you missed to tell)

***
What is unclear:
* the 24V power supply looks huge. Maybe it is designed for more than 100W, but your circuit (at least what we see) draws less than 1W.
If so, it´s quite likely that the 24V SMPS operates outside it´s specified (noise) operating range.


Klaus

 

[haohaodk46]

If I replaced by meanwell power then It is work . So with spms normal power how to filter noise from DC output

 

[D.A.(Tony)Stewart]

If I replaced by meanwell power then It is work . So with spms normal power how to filter noise from DC output

Don’t you have 12v, 5V on your PC PSU or an LDO or anything else?

 

[danadakk]

These might help (and attached) :

https://www.analog.com/en/resources/technical-articles/designing-second-stage-output-filters-for-switching-power-supplies.html

LDOs or post regulators can help, to a point. They have a freq response associated with their
noise rejection ability so it helps to know what the offending spectrum is. Here is a "typical"
LDOs response. Note also pay close attention to output C requirements in datasheet to
insure stability.

Capacitor technology for use in filtering matters. Polymer tants best for bulk,
ceramics and MLCC for high freq. Again if you use LDO the min ESR matters,
otherwise use low ESR for passive filters.

OSCON is polymer tant.

Lastly helpful if you have a DSO scope, put it on infinite persistence, probe power rail. You will see
pk-pk noise and as you try various filters able to monitor progress. A FFT or spectrum analyzer
also useful.


Regards, Dana.

 

[D.A.(Tony)Stewart]

I would expect without datasheet specs to make your linear supply noise less than the faintest echo signal you want. Some sonar IC’s may have good PS rejection, but don’t count on it.

Also you did not specify if your noise was coherent with DC ripple or AC hum. Why not elaborate instead of keeping us in the dark!

 

[haohaodk46]

Don’t you have 12v, 5V on your PC PSU or an LDO or anything else?

I tried a IC LM7805 LDO but It still noise from 24V SMPS

--- Updated Apr 3, 2024 ---

I would expect without datasheet specs to make your linear supply noise less than the faintest echo signal you want. Some sonar IC’s may have good PS rejection, but don’t count on it.

Also you did not specify if your noise was coherent with DC ripple or AC hum. Why not elaborate instead of keeping us in the dark!

I have oscilloscope to catch noise. My issue is if I replace normal SMPS 24V by meanwell 24V then It is work . How to filter noise from normal SMPS 24V ?

 

[KlausST]

Hi,

Yesterday on TV I heared this sentence: (From a professional to an amateur)
"FIRST we collect informations, THEN we decide what to do"

This is exactly my way to solve problems.
--> I´ve told what information I need.

Klaus

 

[D.A.(Tony)Stewart]

photos of layout and block diagram in detail show clean ground on scope.
- connect 0V to PE gnd
- show scope photos and how it is measured