Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Can you name a mains connected product with no input filter whatsoever?

Status
Not open for further replies.
T

treez

Guest
Newbie level 1
Hello,
Please give examples, or if you think all mains connected products must have an input filter...even if only a capacitor across line_neutral.
 

AC motors need nothing, they make no electrical noise
(just power factor, and too bad). Universal motors I often
see some kind of capacitor across the brushes in later
equipment (none on my "antique" metal body type power
tools).

Even "wall wart" (transformer, old school) have often
nothing on the primary side (or had). Sometimes a
ferrite bead on the secondary pigtail after the bridge
and filter cap, if the dependent is a noise maker.

I see more things with "integrated" choke-y "pods"
on the power cord these days, like a Band-Aid for
a design they didn't want to touch the guts of.
 

Thanks, but surely with a dishwasher you need an AC filter because otherwise all that mains bourne noise will pervade into the product and start playing havoc with the control and signal circuitry?
Even if the control and signal circuitry has its own local filter, it must surely also need there to be an AC filter at the upstream end of the product so as to stop the mains bourne noise getting in amongst the signals?
 

Thanks, yes, granted toasters and heaters, which have no IC's in them, dont need any AC Mains filter.....i should have lmited this to products with IC's in them.
 

What IS your point? Things have filters or they don't. So?
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
I am saying that a mains connected product that comprises IC's and signal circuitry , must have an AC mains filter or else it will suffer mains bourne noise.
(Toasters are a point of interest here in UK, i believe that no other country in the world actually eats toast?...toast is considered, and probably rightly, as an abuse of bread, but thats another point)

......Is this true?

...or are there many millions of offline products out there that proove my hypothesis totally wrong?
 

treez said:
I am saying that a mains connected product that comprises IC's and signal circuitry , must have an AC mains filter or else it will suffer mains bourne noise.
(Toasters are a point of interest here in UK, i believe that no other country in the world actually eats toast?...toast is considered, and probably rightly, as an abuse of bread, but thats another point)

......Is this true?

...or are there many millions of offline products out there that proove my hypothesis totally wrong?
Click to expand...

Even a battery operated devices have filters, generally a .1uf on each chip.
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
Thanks yes, but in this case it is talking about mains connected devices, and whether or not they need an AC filter....a filter in the live and neutral entrance into the product....i accept that all IC's in the product will have 100n's on their Vdd pins, though we are speaking of whether it needs specifically an AC filter?
 

This boils down to two things:

1. is the device susceptible to interference from the line.
2. does the device produce interference to the line.

Both are eluded to in earlier posts. By interference I mean anything from infrequent/irregular spikes to signals with a dominant spectral characteristic.
ICs themselves are nothing to do with mains filters, they are either 'victims' of interference or incidental sources of it. Obviously there are design rules to do with individual circuits and maintaining low supply impedance where needed but I see no direct relationship with that and mains filters per se.

So if the product is in category 1. or 2. above, a filter is advised, otherwise it probably isn't necessary to use one.

Brian.
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
betwixt said:
This boils down to two things:

1. is the device susceptible to interference from the line.
2. does the device produce interference to the line.

Both are eluded to in earlier posts. By interference I mean anything from infrequent/irregular spikes to signals with a dominant spectral characteristic.
ICs themselves are nothing to do with mains filters, they are either 'victims' of interference or incidental sources of it. Obviously there are design rules to do with individual circuits and maintaining low supply impedance where needed but I see no direct relationship with that and mains filters per se.

So if the product is in category 1. or 2. above, a filter is advised, otherwise it probably isn't necessary to use one.

Brian.
Click to expand...



If you want to sell your product in Europe, line filters would be a must.
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
barry said:
I don't believe there's any such rule. You must meet regulatory requirements for emissions, susceptibility, etc., but HOW you meet it is irrelevant.
Click to expand...

No real rule, but in most cases a filter is the best way to meet the requirements. Unless your product can take induced pulses in the line. (like a toaster)
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top