I've noticed recently that Phil Frost has posted a few questions and immediately answered no doubt as a form of tutorial, an example is How can suddenly stopping a spinning motor cause my supply voltage to shoot up with the back-EMF can't exceed the supply voltage?

I think they are excellent, but I guess strictly interpreted based on the FAQ statements such as "You should only ask practical, answerable questions based on actual problems that you face" maybe they aren't real questions considering he already knew the answer? Please note that I am not in any way saying they shouldn't be allowed, but maybe the FAQ or elsewhere should clarify it a bit.

The reason I ask is that a few times in the past I've had problems I've been considering asking, but after further research have solved myself at which point I don't consider them a question but the solution I found may be interesting to the general community. So I'm wondering the guidelines for when it is or isn't OK to post them in that format?


3 Answers 3


If I can speak for myself here, I'll tell you my reasons. The first was this:

How can I measure back-EMF to infer the speed of a DC motor?

I read something that reminded me that I knew this, but it basically isn't documented on the internet. If there are search terms that will retrieve this information, I haven't found them.

These two:

How can I implement regenerative braking of a DC motor?
Why should I worry about a motor causing my supply voltage to shoot up when the back-EMF can't exceed the supply voltage?

are the result of a discussion about this one:

Limiting torque on a DC motor

Through that discussion, and other questions I read as research, it seemed to me that there was a feeling in the community that regenerative braking was somehow not present in ordinary motor drive circuits, and that you had to do something special to get it. I know this to not be true from personal experience, after blowing out a few dozen motor controllers until I discovered what was happening while designing one for a small electric vehicle.

I don't feel the slightest bit guilty about the reputation I've received from these. It's not as if the reputation I gain comes at the cost to someone else. I put a lot of time into drawing those schematics, proofreading, editing, researching, and verifying them. For all three of those together, the answers have received 24 upvotes. Not exactly a steal.

How can I efficiently drive an LED?

I wrote this one because there were hundreds of answers like, "Ugh...I'm not going to explain how to calculate the needed resistor again and no, you can't put them in parallel." but really none that took the next step and explained other ways to drive an LED. It's not uncommon for someone to ask about driving a lot of high-power LEDs, and although they are asking about resistors, the answer should really be, "You know, resistors will eat up 1/3 of your battery. You should look at some more efficient methods." I guess when there is some variation of this question every day, it's hard to take the time to write a good answer for each one. I wanted a canonical answer to link to.

If upvotes are any indication, this mundane answer was the most appreciated. It has now 36 upvotes, more than the other three combined. Ironic, since it contained the least interesting information. Still, I don't feel guilty. It filled a real need on the site. It addresses a very popular problem. I must have spent two hours on that answer, drawing the schematics, making the graphs, making sure the language was easy to understand and accurate.

In my opinion, more people should be answering their own questions. If you learn something that is useful but was hard to find, make it easier for the next person. You also give your research a chance to be reviewed by others, to make sure it's correct. This may not be pushing the edge of science, but it is advancing the boundary between accessible and arcane, which is just as good.

This behavior is encouraged by the design of the site, by the "answer your own question" link at the bottom of the "ask a question" page. People won't game the system by flooding the site with useless information. This wouldn't get any upvotes, and it would attract the attention of moderators if it got bad enough.

  • \$\begingroup\$ Thanks Phil. I only used you as an example because your Q/A was the most recent one and excellent as I mentioned and knew your intentions were noble. I was only seeking clarification and querying if something like that should be mentioned in the FAQ. I've answered my own questions on stackoverflow before (which I knew was encouraged) but only when I didn't know the answer to begin with and later worked it out. I just thought it may be something that could be more clearly spelled out in the FAQ. \$\endgroup\$
    – PeterJ
    Jan 28, 2013 at 8:05
  • \$\begingroup\$ No need to feel guilty - any material that adds value to the site is definitely encouraged. The real point of the site is for folk to learn, and the more quality material the better. It's obvious you made an effort with the (excellent) answers and since votes are the way of saying "thanks, that helps" around here, they are well deserved. \$\endgroup\$
    – Oli Glaser
    Feb 1, 2013 at 0:26

If you have a question that you would like to ask and you answer it, but think the question/answer would be helpful to some of the broad audience of the internet and others could use it, Post it!

This has always been a messy subject, I feel posts like this are very useful, take a look at our list of "FAQ" questions, the first one is the same thing from Olin.


You should definitely ask and answer your own questions. This is explicitly encouraged.


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