SBooster

I think we all know by now what this section is for.
User avatar
jack
Thermionic Monk Status
Posts: 5493
Joined: Wed Dec 29, 2010 8:58 pm
Location: ɐılɐɹʇsnɐ oʇ ƃuıʌoɯ ƃuıɹǝpısuoɔ
Contact:

#16

Post by jack »

Going "outside the box" a bit...

I'd be interested in a comparison between your results and trying a standard off-the-shelf IEC mains input filter - connect +ve and -ve to either live or neutral (doesn't matter which way round) and the case to GND.

The cheaper IEC filters are single stage, the more upmarket ones are two stage and provide great filtering at RF.

Your graphs show about 25dB reduction in noise up to 50kHz - these mains filters do at least that and obviously attenuate far more at higher frequencies... Note that some mains filters don't attenuate much up to 100kHz, but there is noise, and then there is noise (differential,common mode etc.)

The 3EMC1 3A single phase filter is a good example - 3EMC1 data sheet - there are many others... e.g. look at the TFK-3 graph in http://docs-europe.electrocomponents.co ... 02a7d7.pdf

Half the cost (if it works) and not boxed "magic". Using an IEC 60320 C14 inlet connector with included filter would be cheaper, but those tend to be single-stage filters...

Edit: More - http://www.audiomisc.co.uk/mains/filters1.html - rolling your own wouldn't be tricky... what about just passing the power leads several times through a ferrite core?

etc.
Vivitur ingenio, caetera mortis erunt
User avatar
Paul Barker
Social Sevices have been notified
Posts: 8863
Joined: Mon May 21, 2007 9:42 pm

#17

Post by Paul Barker »

We always used to make our own.

The cheapest source of basic EMI supressors are in dead microwaves and washing machines.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
User avatar
jack
Thermionic Monk Status
Posts: 5493
Joined: Wed Dec 29, 2010 8:58 pm
Location: ɐılɐɹʇsnɐ oʇ ƃuıʌoɯ ƃuıɹǝpısuoɔ
Contact:

#18

Post by jack »

Electronics Goldmine selling good two-stage ones for only $2.50
http://www.goldmine-elec-products.com/p ... ber=G19096

Type STE8-3 from SAE Power Inc.

Data sheet here: http://www.saepower.com/pdf/emi-filter_catalog.pdf

At 150kHz, common mode 58dB down, differential 36dB down.
Vivitur ingenio, caetera mortis erunt
Neal
Shed dweller
Posts: 2299
Joined: Fri Aug 03, 2007 10:57 am
Location: From the land of the Bodgers

#19

Post by Neal »

Nick, thanks for the links...easy enough to role your own. Tried the ferrite ring and it made no difference to SMPS switching noise at all...
Post Reply