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zaphod

Regular Member

Joined: 03/06/2018
Location: United Kingdom
Posts: 93

Posted: 01:26pm 10 Mar 2019

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Hi all, may I apologize for posting a high frequency converter!

This one is enclosed in an A4 page sized letterbox and as can be seen from the picture whilst on bench test quite full.

Power is limited by the test harness but this is sufficient to do a basic EMC pass. Without expensive facilities and test gear it is difficult to get comparative results from EMC, buzzing or not buzzing on the radio not being particularly helpful.

I use my DSL modem along with some software that gives me a rolling signal to noise ratio plot, it is pretty sensitive and will usually detect EMC before the radio does and more importantly gives me a repeatable measurement so different improvements can be trialed.

Enough of the dark art of EMC, this converter is only used to defray the household electricity costs when the PV has done heating the water, it doesn't need to start motors as I am also attached to the grid, there being no batteries in this system either. I also ensure I do not export by a gadget fitted at my meter that digitally reports power and direction, I don't want to wear my gear out powering other people for free :)

Everything I do is economic so the letterbox case was chosen as being a hell of a lot cheaper than industrial enclosures, and it adds a challenge to make everything fit!

Edited by zaphod 2019-03-11

Cheers Roger
1Kwp DIY PV + Woodburner + Rainwater scavanger :)

Ralph2k6

Senior Member

Joined: 24/09/2017
Location: Australia
Posts: 129

Posted: 10:58am 11 Mar 2019

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Nice work.
Is this the same unit you were designing that was giving you troubles some time back?

Ralph

zaphod

Regular Member

Joined: 03/06/2018
Location: United Kingdom
Posts: 93

Posted: 08:17pm 11 Mar 2019

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Hi Ralph, yup I reckon so and thank you for the compliment :) I work in slow motion, to many hobbies so each thing gets nudged forwards a bit at a time! The major problems I have dealt with in the last few months have been severe EMC, unfolder unreliability and trafo saturation from sub-harmonic oscillation. It now runs quite merrily but still has a little more EMC than I would like when joined to the full system as there are competing issues between it and the rest, still I like a challenge :)

I got a lot of EMC help from Wurth mostly because there site has very good models (for simulation) and they are great with helping out if you know your onions :) LTspice remains a brilliant unbeatable FREE tool!

Cheers Roger
1Kwp DIY PV + Woodburner + Rainwater scavanger :)

Ralph2k6

Senior Member

Joined: 24/09/2017
Location: Australia
Posts: 129

Posted: 12:02pm 13 Mar 2019

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Hi Rodger,

I really need to practice with LTspice. Tried once or twice to no avail. Gotta find guides perhaps.
Know what you mean with too many hobbies, I've got so many pots on the boil it ain't funny

Ralph

zaphod

Regular Member

Joined: 03/06/2018
Location: United Kingdom
Posts: 93

Posted: 02:47pm 13 Mar 2019

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Hi Ralph, well I started in Spice long ago, I bought a book ISBN 0-13-124652-6 that's a bit heavy going but there are many tutorials these days on the web.

It's very flexible and you can just about model anything electronic, I just managed to pin down and fix an EMC problem that was vexing me by modeling it in spice first, sometimes it takes a bit of thought as to how to model and extract data from something but many times I have found it very useful, definitely worth learning if you are into any kind of analogue or switching electronics :)

Cheers Roger
1Kwp DIY PV + Woodburner + Rainwater scavanger :)

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