Arduino Forum

Using Arduino => General Electronics => Topic started by: paimpozhil on Mar 19, 2013, 07:20 pm

Title: how to reduce the electrical noise
Post by: paimpozhil on Mar 19, 2013, 07:20 pm
Hi All

My arduino standalone board that i soldered with voltage regulator for staircase lights automation seems to be restarting/flickering whenever i switch on my tubelight which flickers almost every time due to start issue or whatever.

Is there anyway to immunize the arduino from power glitches like this? like bigger caps for voltage regulation,etc?

Someone suggested keeping a lower value resistor for reset instead of 10k, how lower that should go?

Running the arduino from the batteries will fix?  or may introduce more problems than the fix?
Title: Re: how to reduce the electrical noise
Post by: retrolefty on Mar 19, 2013, 07:40 pm
Well without a complete wiring diagram including power source it's hard to give you specific advice, but yes proper filtering and bypass caps of appropriate size and applied correctly can generally deal with your problem, which sounds more like voltage sage due to load switching rather then just random circuit noise.

Lefty
Title: Re: how to reduce the electrical noise
Post by: paimpozhil on Mar 19, 2013, 07:48 pm
Ok I basically use the same version here

http://arduino.cc/en/Main/Standalone
2 10uF capacitors.
Without the PUSH button to reset and the in-circuit programming chips
with exactly same parts and wirings.. I have soldered them all in the solder board. I will take a photo very soon


Power source is my grid and wallwart 12V , I have used voltage regulation in the circuit using the 7805 .
Title: Re: how to reduce the electrical noise
Post by: paimpozhil on Mar 19, 2013, 07:49 pm
What is the next size of caps I can try instead of the 10uF?
Title: Re: how to reduce the electrical noise
Post by: Grumpy_Mike on Mar 19, 2013, 07:57 pm
Quote
Someone suggested keeping a lower value resistor for reset instead of 10k, how lower that should go?

Ignore him he knows not what he says.

Quote
2 10uF capacitors.

put 2 ceramic capacitors of 0.1uF in parallel with the ones you have. Mind you the capacitors shown on the link do not look like 10uF at all they look like 10nF.

Quote
I will take a photo very soon

Good.

Quote
I have used voltage regulation in the circuit using the 7805

Have you got capacitors on the input and output pins?
Title: Re: how to reduce the electrical noise
Post by: mixania on Mar 19, 2013, 08:03 pm
I think a pull-up resistor between a pin and VCC would help.
Title: Re: how to reduce the electrical noise
Post by: paimpozhil on Mar 19, 2013, 08:09 pm
Hey ,

Thank you for replying .

I will try the 0.1uF caps in parallel, but I have to buy them tomorrow to try.

I have capacitors on both sides of the 7805.



Quote
Someone suggested keeping a lower value resistor for reset instead of 10k, how lower that should go?

Ignore him he knows not what he says.

Quote
2 10uF capacitors.

put 2 ceramic capacitors of 0.1uF in parallel with the ones you have. Mind you the capacitors shown on the link do not look like 10uF at all they look like 10nF.

Quote
I will take a photo very soon

Good.

Quote
I have used voltage regulation in the circuit using the 7805

Have you got capacitors on the input and output pins?
Title: Re: how to reduce the electrical noise
Post by: paimpozhil on Mar 19, 2013, 08:10 pm

I think a pull-up resistor between a pin and VCC would help.



Which pin and VCC ? sorry im very new to arduino land.
Title: Re: how to reduce the electrical noise
Post by: mixania on Mar 19, 2013, 08:22 pm


I think a pull-up resistor between a pin and VCC would help.



Which pin and VCC ? sorry im very new to arduino land.


For example: If you are using a wire (you would actually be using at least two in this case) to communicate with another Arduino. And you would want to reduce the noise, consider connecting a part of the wire to the vcc through a pull-up resistor. Connect the end of the wire to the final destination.
Title: Re: how to reduce the electrical noise
Post by: SirNickity on Mar 19, 2013, 08:42 pm
I don't usually build a circuit with PSU rail caps less than 100uF.  Often, 470uF.
Title: Re: how to reduce the electrical noise
Post by: paimpozhil on Mar 19, 2013, 09:16 pm

I don't usually build a circuit with PSU rail caps less than 100uF.  Often, 470uF.


Now If i replace my 2 10uF with lets say 470uF, u think that would improve/help this ?
Title: Re: how to reduce the electrical noise
Post by: MarkT on Mar 19, 2013, 09:57 pm

Hi All

My arduino standalone board that i soldered with voltage regulator for staircase lights automation seems to be restarting/flickering whenever i switch on my tubelight which flickers almost every time due to start issue or whatever.

Is there anyway to immunize the arduino from power glitches like this? like bigger caps for voltage regulation,etc?

Someone suggested keeping a lower value resistor for reset instead of 10k, how lower that should go?

Running the arduino from the batteries will fix?  or may introduce more problems than the fix?


I think this thread has drifted off track rather - as I understand this there is a fluorescent light fitting that's creating
mains transients that are reseting the Arduino by some mechanism.

Likely things are:

1) inadequately protected power supply passing on the transient to the 5V rail
2) interference being picked up by cables between the Arduino and the staircase lights.

But I've a few questions:  What are these staircase lights?  Are they distinct from the fluorescent light
that is causing the problems?  How are the staircase lights controlled by the Arduino?  Are relevant
logic-level signal cables shielded and routed away from mains wiring?
Title: Re: how to reduce the electrical noise
Post by: paimpozhil on Mar 19, 2013, 10:18 pm
Hi  MarkT,

Staircases are CFL lights  and yeah they are totally independent of the florescent

There are 6 of them and I have wired all of them to relay board which has 8 relays and an ULN2003.

I have ensured the digital wires and AC mains wire are separated out by few inches.


Title: Re: how to reduce the electrical noise
Post by: Grumpy_Mike on Mar 19, 2013, 10:23 pm
That dosn't matter. It is electromagnetic induction that couples the interference.
Title: Re: how to reduce the electrical noise
Post by: MarkT on Mar 19, 2013, 10:34 pm

Hi  MarkT,

Staircases are CFL lights  and yeah they are totally independent of the florescent

There are 6 of them and I have wired all of them to relay board which has 8 relays and an ULN2003.

I have ensured the digital wires and AC mains wire are separated out by few inches.





A few inches isn't great - route them completely away from each other.  sheided cable is good,
ferrite toroids can be good to reject common-mode transients.  You may also have a ground loop
which you need to think about - bring the mains to the relay board and Arduino PSU in one place
to avoid such a loop.
Title: Re: how to reduce the electrical noise
Post by: paimpozhil on Mar 22, 2013, 11:44 pm
Hi MarkT,

Thanks for the answer,

To keep everything out of equation I disconnected all my PIRs and kept the arduino to the minimum.

I measured the voltage across the +5 and GND.. while the Flourascent light is flickering.

I saw voltage spikes upto 6 or 7 sometimes even more during this and hence the AtMega is restarting.. Is that possible?

Will atmega reboot when this happens?

I use the same wallwart to power the ULN2003 for  8 relays as well as the ATmega . will this cause Ground loop?

Title: Re: how to reduce the electrical noise
Post by: paimpozhil on Mar 22, 2013, 11:49 pm
I use a 7805 with 2x 470uF decoupling capacitors .. and I see more than 5V during the light flickers ..

Input is 12v from the wallwart which already has its own regulators. should i replace wallwart and try?

or should i change the voltage regulator IC to be something better than this?

Title: Re: how to reduce the electrical noise
Post by: paimpozhil on Mar 22, 2013, 11:57 pm
OK I have measured the voltage across my 12v wallwart lol it goes UPTO 35V during flickering.

I tried to replace my nokia phone charger and see what happens, it keeps its voltage stable..

I think the problem is my cheap crappy wallwart.. everyone agrees?

Title: Re: how to reduce the electrical noise
Post by: Grumpy_Mike on Mar 23, 2013, 10:50 am
Yes it sounds like that is right. You could always get a zenner diode across the supply to try and clip any voltage spikes on the line.