How to make an XT90 Loop Key

[moon]

This diagram is all I needed

Maybe you should add one to the first post @b264

[b264]

@moon Done

Thanks @iespobolamas, I edited your image slightly and added it to the top post

[moon]

Thanks I felt like you taught us how to solder it all but not how to wire it thanks

[iespobolamas]

Awesome!

is there a reason some people use Anti Spark devices instead of a loop key? this seems way simpler and less likely to fail

[Flasher]

Imo people chase the dream of perfectly watertight cases. Having a foolproof antispark with push to start inside the enclosure is a step closer to reaching that goal

[iespobolamas]

thanks, so there’s no functional difference in what they do?
I’ll stick with a loop key and some hot glue :)!

[Flasher]

As to differences, @b264 aka “the breaker of antisparks” (yup I rebaptised you) would have more info as to why he keeps trying to have one that works

[b264]

@iespobolamas

is there a reason some people use Anti Spark devices instead of a loop key? this seems way simpler and less likely to fail

Tackling the anti-spark problem (Title by a good friend)

Most “inrush limiter circuits” fail because they are operating in linear mode during inrush. It’s a design limitation on almost every one. Imagine a FET is a resistor with a variable resistance. When it’s “off” the resistance is [nearly] infinity and when it’s “on” the resistance is [nearly] zero. That’s all fine and dandy until you add capacitors to the load, like the filter capacitors on VESC and other ESCs. Right when it turns on, it’s effectively a momentary short circuit with [not really…]…

TL;DR there aren’t really any “good” options for that yet. Once there are, loopkey will be cheaper. Until then, loopkey is better and cheaper.

[iespobolamas]

thanks Brian

[murdomeek]

I know “traditional” switches are not used because of the spark. But do 90a rated toggle switches with a bleed resistor exist?

Pretty much a look key, but instead of ripping it out, its like a traditional switch. (More noob friendly i guess)

[mmaner]

the only one I have found is here. It doesn’t look incredibly robust and its still 30 bucks shipped, so I don’t see an advantage over existing AS switches.

[Zach]

Check out @deckoz’s as150 anti spark switch!

[iespobolamas]

Trying to make a more compact loopkey,
any thoughts re encasing the bare joints in epoxy resin,
does it conduct at all once fully cured? or maybe just fill it all with hot glue?

[KaramQ]

Jb weld is your best shot

[iespobolamas]

thanks, is JB weld not conductive?
the goal is to insulate + from -

[KaramQ]

I have no clue, summoning @b264

[Skunk]

Yes. It can be conductive.

[yelnats8j]

Liquid electrical tape and then resin just to be safe would be what I would do.

[Flasher]

Be extremely careful with jbweld. Some variants contain actual metal powder in them (example:steelweld)
Epoxies are non conductive unless you specifically buy one that is used to be conductive (example: thermosetting epoxy for PC repairs)

[iespobolamas]

Thanks @yelnats8j @Flasher!

I’d never heard of liquid electrical tape, going for some of that then cast some resin in there.