@adamaero The funny thing is that MEs often don't design heatsinks either. [Afterthought don't count.]

@anonymous2 What kind of application is this kind of light for?

Oh sorry the idea is to do a kind of 10 times exposure (akin to a double exposure) to measure the speed of a sort of pneumatically accelerated piece of metal; I can only measure the velocity over 5cm and it could be going as fast as 100m/s. The strobes are so that the film (or optical sensor) only exposes every microsecond or so (I'd probably be ok down to every 10 microseconds, but I'm aiming for the highest precision possible since it's an academic research project)

Which is why I want pretty fast rise and fall times... I could theoretically let it go slower but if the velocity ends up being higher than anticipated I'd rather not have to start from scratch since the goal is to keep it relatively cheap (it's a sideline on the main research project)

@forest I looked at PWM, but I really have to have the light source on for a much shorter time than it is off, otherwise my double exposures will be really fuzzy and determining how far the piston travelled in the time between the pulses will be more difficult

There might be LEDs designed for strobing, if you're OK with it simply repeating and not being programmed. That might be better because all the circuitry could be minimized and kept within the package (which should reduce inductance).

Good idea, I'd rather be able to programme it to get a maximum of 10% duty cycle on the pulses but it could be a cheaper more reliable option

Is a high-speed camera not an option?

Definitely a better option I just haven't convinced the powers that be that it's worth paying for, I looked into renting but couldn't find anything in my region under $2500

And even at that they were tentative quotes and if it takes longer than anticipated then the price tag goes up

I also looked into trying to set up parallel lasers on one side of the piston and photodiodes on the other side with a logic analyzer collecting the signal attached to a RPi but I was having trouble finding a way to guarantee that they were parallel

And the more points I try to sample the more space problems I have

@NickAlexeev I don't think anyone designs them here. They just go bigger if it gets too hot (I think).

@SamGibson thanks for stepping in, I was a bit sad and should probably have been more relaxed

s/advise/advice/

@MarcusMüller - Hi, I was in the middle of something and just locked that topic so I can review in the next 20 mins or so. Although you shouldn't have replied to the comments on that EE.SE question (I guess you know that already) it seems that others "attacked" you first and obviously I'll look into that.

@SamGibson yeah, I just should not have reacted at all; but what's confusing to me is that Jack0220, whose questions I've answered on both Ham.SE and Physics.SE (to pretty positive feedback of the respective communities) would now go and try to "discredit" me. I don't really care enough to lose sleep over that, it just seems to be detrimental to my willingness to work with posters I don't have a positive memory of :-/

@MarcusMüller Although I can't see the details of voting on that Ham.SE site (I'm only a mod here - one site is enough!) I can contact the mods for that site. Please also flag one of your own downvoted answers on that site using the "other moderator action" option at the bottom of the list, and explain that you believe it is revenge downvoting. They can investigate, althouh I cannot promise any specific result.

Thanks!

@MarcusMüller Understood - none of us have to answer questions from those who cause problems. I have my own "don't answer questions from these people" list :(

@SamGibson that's kinda sad :(((

@MarcusMüller Just to be clear, please explain that you believe it is revenge DV from this EE.SE site (so that they don't try to find a cause over on Ham.SE). I wasn't sure if I was clear enough in my comment above.

yes, I'll say exactly that; I'll link to the chat messages here

Good, that sounds like a plan.

I'm not yet sure that I agree with the position to disallow identification questions for repair purposes, but that is (as you say) a discussion that should be done on Meta and not for the main site.

yeah, it's a bit of thin line to walk, honestly.

And even if I do disagree, you were polite about it - and got attacked, and such attacks are not allowed.

Yes, it is a thin line.

If there is future value for the question, I tend to think it should stay.

If there is no future value, like many repair questions which are just too specific to that one situation, then the "repair question closure reason" applies.

I see you linked to a previous Meta topic and mentioned Dave Tweed - I will look there when I have a few more minutes.

I'd say my preferred way of dealing with this (and you might disagree!) would be finding one reference Q&A for "I've burned my regulator, can someone help me identify it (so I can fix this appliance)", where the answer explains that,

even if we find the exact part and a place to order it, it's still going to be likely to be a cascade of failures, and lest you can really isolate the fault, chances are more than that is damaged, and it'll require at least some expeirence and maybe some fundamental test equipment usage experience and said equipment to actually fix it. Plus, power semiconductors tend to be a pain to solder.

And then we use the "Does this help you (duplicate of...)" close vote, which is actually helpful, as it explains things! Then, the community can honestly vote on "yeah, this is really answered by, naaaah, even if someone tells you the part nr, you'd still end up needing to fix something out of your pay grade" or for keeping it open as a question that contributes something new on its own.

I think we really might have enough burnt regulator ID questions out there that a few of them should have really good and helpful answers :)

My concern is that if we try to introduce a rule that identification Q are allowed unless they are being used for a repair, it becomes very difficult to "police" such a rule. OPs will then hide the purpose of the question etc. My initial view is that it will cause future problems - but I don't have the bandwidth to think about it right now. I'm up to my neck in stuff here!

I will look at the EE.SE Q which happened - I might need to extend the lock for a little bit, to give me some time. I will ask that discussions about what is allowed should be taken to Meta and not discussed on that question.

@MarcusMüller - Any more Q before I go AFK?

no, you've been super helpful, also for my Mood, Sam!

@MarcusMüller - OK! Have a good what's left of your day. I'll investigate that EE.SE Q. Please ping me here if needed. Bye for now.