So to shorten it all, the FETs get hot on startup on this model.
No, thats not the case. The time between OFF and fully on is less than 3 seconds and the power that needs to be dissipated during that period is relatively small. To put it to perspective, the switch would work just fine during the turn on time and under moderate load without any heatsink at all.
Iām thinking customers who buy this āanti-sparkā will expect to not have spark unlike when connecting the wires manually. So, how does making the FETs do the heavy lifting eliminates spark? Like do sparks happen āinsideā the FET when they close the circuit?
Technically yes, sometimes when mosfets working in not comfortable zone they just give up and inside small spark happens which makes mosfet permanently dmg and always on which makes switch not work anymore.
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This means during ālinear operationā or āhigh Rdsā, which is the same time when they are disspating energy as heat from inside the FETs
This is opposed to ādigital operationā where they are always fully-on or fully-off
@mtuan293 Yes as Kug3lis said, there can be a āsparkā which burns the semiconductor inside creating carbon which is conductive and that leads to the FET being shorted permanently.
@b264 I am not sure why you think that the FET can not operate outside of the digital operation?
I donāt. You said that, not me.
I said it gets hot when operating in the linear region. This getting hot is what causes these devices to fail. If not for that, they wouldnāt ever fail and loopkeys wouldnāt be so popular.
Thatās why I started asking if this one worked that way, but you kept sidestepping the question and attempting to create confusion. One swift ānoā would have sufficed.
I may have not explained what I meant enough. I think you mean when I was talking about the FETs burning/shorting during turn on. What I meant to say is that if you turn the FET on completely right away without limiting the current with higher RDSon you will get sort of a spark or a break through of the semiconductor due to the high current being allowed to pass through. That is why the FETs are not turned on completely right away but after some time has passed and the CAPs are charged.
I dont think I was avoiding answering your question or sidestepping as you say. I said my answer to your question followed by an explanation of why it is so. And once again, I dont mean to create confusion.
So then the answer is no, but you said yes, causing all the confusion.
There is not a precharge circuit. There is an inrush-limiting circuit with the main FETs operating in the linear region.
Thatās all I was asking.
Intentionally creating confusion, in the name of more sales, is never a good strategy. This is a nice innovative product and it can stand on its own. Nobody expects every product to have every feature. But we want to know what it has.
Your alternative approach to the same problem is novel and may end up being better. But you need to be honest.
Okay I see what you mean. I dont mean to be rude but here is a wikipedia page https://en.wikipedia.org/wiki/Pre-charge where the pre-charge is described. You can see that while the page is obviously talking about the āpre-chargeā there is stated that pre charge function/feature is implemented into circuits to prevent inrush current. So precharge=inrush limiting. So based on that I think that these terms are interchangable and mean the same thing. I am stating the facts, if you think it means something else show me some kind of a proof that you are correct. I will be more than happy to admit that I was wrong. However the fact that you think something means what it does not is not my problem and if you think I am spreading confusion to increase sales you not only do not know me but you think it based on what as of now to me seems is incorrect terminology. Dont take it offensively, I dont know how to word it to make it sound less meanā¦
Thatās the reason I asked such a specific question to rule that out.
with emphasis on
and
So the answer is clearly no, not yes.
Okay, I think this is explained well enough now. To summarize it, the FETs operate in linear region and they are driven partially open to limit inrush current for a short period of time after the button has been pressed and after that, they open completely.
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So this makes anti-spark well, anti spark right? If not then itād be pointless since thereās still spark inside to destroy the FETs.
Also have you seen this Flipsky switch? I suspect they copied your design.
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It is an anti spark switch. The spark inside mosfets is just what causes the switches to break if not made properly so no worries here.
Yes I have, I actually forgot to reply to a thread regarding that so thank you for reminding me! 
I was honestly expecting this to happen, not only because it has not been done before and as with everything the cheap spin-off companies will jump on the band wagonā¦ Plus there was an order of 10 straight to Shenzen in some company name so I was āreadyā for this 
EDIT: I did not notice you linked the regular switch, I was talking about the push to start switch. They did not copy my design on this regular one, these are pretty common.
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Glad I found yours. Was about to purchase on Flipsky website. Hell they sell it for $10 more than yours! EDIT: oh yea I was talking about their regular one. The push to start one looks so obvious lol.
So if I order now on your site, itās the latest version right?
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Yes it is, shipped tomorrow the soonest since it is 1am on Saturday here.
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Ordered! I also added a note I want xt60s soldered on too, hope you can do me a favor 
Flipskyās switch doesnāt have push-to-start. Push-to-start combined with auto poweroff means you donāt need a power button or loopkey which drastically helps in the effort for water resistance. Less holes in the enclosure is always better.
TL;DR: use @Martinsp antispark instead
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I was talking about their standard one though. And they do have a push to start one (prob copied from @Martinsp design)