user31105: My question is very related to:
6 downvotes in 6 days - what am I doing wrong?
However, I have 11 downvotes in about two weeks.
The answer given (I upvoted them), but seem not to be related to my questions because:

I'm not a newcomer at StackExchange
Most questions have (multiple) upvotes
For none, there is a reason added
Some of the questions are very old
I never had so many downvotes in such a short time (unless for a single question just asked, which I either removed or improved).

Meaning, it's not 'bad luck'. I just think it's somebody picking on me. Now I don't care if it cost me 20 or 100 points, but if he also downvotes other people who are new, they might cause people to stop using StackOverflow sites, and for me it was and still is an invaluable source of information.

user4143: Looking at your reputation changes over time it certainly does look like someone is out to get you. From the 21st of August there is just a constant stream of down votes and not much else.
Unfortunately we cannot see who is voting, but there are systems in place to identify serial voting by one person and reverse them. But that hasn't been triggered, so I guess it's not just one person picking on you - either that or it's one person who knows how to game the system.
There are people around who think that programming questions are off-topic here, even if that programming is for an Arduino, and a number of your down votes could be put in that category, but not all of them.
Is it just "bad luck"? That's not really possible to tell. The questions in question (questionception?) are mostly quite old, though, so they've either been stumbled across in a general search (but why would there be so many together then?) or someone has actively gone through your list of questions.
Certainly it does seem on balance that it's someone malicious.
Unfortunately there's nothing we as moderators can actively do about it, other than passing it up the chain to the system admins to investigate.

31105: <p>My question is very related to:</p>
<p><a href="https://arduino.meta.stackexchange.com/questions/2565/6-downvotes-in-6-days-what-am-i-doing-wrong">6 downvotes in 6 days - what am I doing wrong?</a></p>
<p>However, I have 11 downvotes in about two weeks.</p>
<p>The answer given (I upvoted them), but seem not to be related to my questions because:</p>
<ul>
<li>I'm not a newcomer at StackExchange</li>
<li>Most questions have (multiple) upvotes</li>
<li>For none, there is a reason added</li>
<li>Some of the questions are very old</li>
<li>I never had so many downvotes in such a short time (unless for a single question just asked, which I either removed or improved).</li>
</ul>
<p>Meaning, it's not 'bad luck'. I just think it's somebody picking on me. Now I don't care if it cost me 20 or 100 points, but if he also downvotes other people who are new, they might cause people to stop using StackOverflow sites, and for me it was and still is an invaluable source of information.</p>
 4143: <p>Looking at your reputation changes over time it certainly does look like someone is out to get you. From the 21st of August there is just a constant stream of down votes and not much else.</p>
<p>Unfortunately we cannot see <em>who</em> is voting, but there are systems in place to identify serial voting by one person and reverse them. But that hasn't been triggered, so I guess it's not just one person picking on you - either that or it's one person who knows how to game the system.</p>
<p>There are people around who think that programming questions are off-topic here, even if that programming is for an Arduino, and a number of your down votes could be put in that category, but not all of them.</p>
<p>Is it just &quot;bad luck&quot;? That's not really possible to tell. The questions in question (questionception?) are mostly quite old, though, so they've either been stumbled across in a general search (but why would there be so many together then?) or someone has actively gone through your list of questions.</p>
<p>Certainly it does seem on balance that it's someone malicious.</p>
<p>Unfortunately there's nothing we as moderators can actively do about it, other than passing it up the chain to the system admins to investigate.</p>
