EEVblog

[@garychap8384]

Nichrome wire would be more efficient and much faster I think. A more challenging problem is how to train a rat to turn on the bench supply : )

[@sciguy14]

Also, (and this is super nitpicky), Kelvin is not a degrees measurement. It's just 80 Kelvin - not 80 degrees Kelvin, for example. My Chemistry teacher used to yell at us when we said "degrees Kelvin"...

[@douglas787]

What I like about this video, is that is shows a simple, cheap way to trigger a spring or cut a holding string. Sure, there are solenoid units that will do the job, but they weigh more, cost more, and have moving parts and there are more things that can go wrong. This method is cheap, simple, low cost, low weight and reliable if the resistor is only used once. Great video and genius idea.

[@sciguy14]

Brilliant idea - never would have thought of something some simple. The obvious disadvantage is that it's a one-time-use scenario. But I suppose that even with a solenoid you'd still need to reset the device...

[@EEVblog]

@axel1973w You missed the point entirely. It's got nothing to do with the actual mouse trap, it's just another possible method to one-off trigger whatever widget that it might be suitable for. The resistor doesn't need power either until triggered. I've actually seen it used in two different scenarios, both military.

[@jhoward98]

A very creative and simple idea to get the brain juices flowing! I actually liked your creativity. I was expecting you to do something that would require more, but was happy to see how simple you made it.

[@wayneherby5449]

That's not a mouse trap, now THAT's a mouse trap :P

[@AntiProtonBoy]

Regarding the thermal dissipation via the resistor leads, I think it would have been worthwhile to mention that hot resistor leads can stress solder joints, and cause premature failure in some cases.

[@KozmykJ]

Pull the pin with a bi-metal strip. and you've got a resettable current/heat triggered trap.

[@EEVblog]

@karmicthreat The original proposals did not dictate that an easy reset was required.

[@44R0Ndin]

I've heard of this kind of system being used to cut the reefing bands on parachutes. Also to cut loose drouge chutes after they drag the main out of its container. Reefing bands are basically a line around the shroud lines of a circular parachute that prevent it from opening to its full deployed diameter, which is often done to reduce the g-loading shock that would otherwise occur if it went directly from packed to fully deployed. Reefing bands are also used to control decent rate in order to limit wind-induced drift. The reason they are found on parachutes so much is because they are easily triggered, absolutely dead simple, and can be made extremely lightweight. Because they are so simple, they are extremely reliable. Not much to go wrong with a resistance based heater, and resistors aren't static sensitive. Also, resistors and wire are dirt cheap, so they don't cost an arm and a leg, meaning using 2 or more of them for redundancy's sake isn't going to break the bank.

[@EEVblog]

@ParadigmaticShift Yeah, just like there is no such thing as "10 puff", "10 mic", "10 R", and "ac current" right? The real world isn't an english exam. Degrees kelvin stands! :-P

[@malcolmholmes115]

This T-shirt makes me even bigger fan of your channel

[@ib9rt]

@jnrolf No, Dave was right. 35 Kelvin degrees = 35 Celsius degrees. Remember we are considering temperature differences, not absolute temperature measurements. Degrees in this case means "degrees of difference".

[@philbx1]

Great to see some fun stuff from you again Dave! BTW, I seem to remember someone trialling the fishing line approach as a trigger to early bushfire detection. A small DC geared motor with 'winch' setup with microswitch would probably also be the go, although that's a bit OT re. your fine talk on resistors...

[@jesseespinosa3325]

I had a similar problem to solve triggering a spring arm at a distance. one 20 guage-ish strand of copper cannot handle much current so I just used the copper as my trigger wire that needed to be cut, 120v dead short across the wire melts the wire for you faster than a 15a breaker can trip. can also be used to light a match at a distance, be carefull though!

[@FennecTECH]

I love how you can see the flicker of the fluro tubes

[@karmicthreat]

It works. But seems kind of a pain to reset. If you want to use Ohm's law you could use a piece of nitinol/flexinol shape memory wire to pull on the arming latch. But it was a good excuse to say something about resistors anyway. How about a vid on the effects of the temperature coefficient on resistance or voltage regulators? Seems to catch some new people when they are trying to make something precise.

[@johndoe-gr3mj]

Dave you can also use a 9 volt battery and copper wire. Or get an old flashlight bulb, break it and use the element for heat.

[@Shoetiefly]

I often sail solo at night with the boat's tiller held with control lines. If I fell off the boat, the boat would keep going. I have been considering various inexpensive one-off MOB (man overboard) devices to release the tiller if I fell off and a sensor contacted water and triggered the release automatically. I think this resistor burn has potential for this application. A second question for the experts is how to signal the boat while in the water. A small radio ?

[@EEVblog]

@xXdenhartXx otherwise that graph shows one mighty cold resistor!

[@chandin69]

I did somehting like that as a kid, though there are times when you need it to be portable and reliable(Operating almost instantaneously everytime). what i did was i got a flash circuit board from a camera and rigged up a cct to trigger it by remote, then i send all the juice in the fat capacitor to a resistor. I used SMD resistors(less than 6ohms). they explode everytime, great for setting off fireworks:)

[@barcelona08018]

I've heard of a similar method used as an emergency cut down for high altitude balloons (cut through the nylon lines connecting the balloon). I think they might use nichrome wire though.

[@freespuddy]

Interesting way to release the spring. It reminds me of how I used nichrome wire to start my homemade rockets and to start a firecracker fuse to scare dogs pooping in my yard.

[@robertherberg9595]

What are you doing Dave?

[@ib9rt]

@jnrolf If the thermal resistance is 140 K/W then it is also 140 degC/W. Kelvin degrees and Celsius degrees are the same size (in other words, when converting one to the other the multiplication factor is 1).

[@EEVblog]

@Vlakpage Of course it's about English, the physics doesn't care!

I used resistor like this to fire up the rocket engine. But it was powered by a 350V150uF capacitor, charged with a flyback converter. Reaction was rapid, but resistor destroyed totally.At first looking at the video I was sure you'll construct an optoelectronic barrier or something to trigger a mousetrap ;-) Still don't understand linear graph of power dissipation of the resistor. Shouldn't look like this accoring to me.

[@iamtheug]

although this clearly worked and is probably the most elegant, for learning's sake, could you modify a fuse to create a break away?

[@rocketman221projects]

Thin nichrome or stainless steel wire works well too and it doesn't stink the place up like fried resistor.

[@adamlumpkins2000]

dave, I did some work with graphite It works great as an ignter..... there are many different sizes. I had some luck useing them as resistors just thought i would throw that in there

[@MrBanzoid]

Bloody big mice in Australia!

[@JoannaHammond]

+MrBanzoid What do you expect, is there anything in Australia that is either not huge or poisnous?? Seems like all the wildlife in the country just wants to kill you.. ;)

[@CampKohler]

You didn't indicate how long it takes to melt the line. I would use a 1/8-watt resistor to hold down the lever (one end on the lever and the other on the trap base), then apply enough current (say from a large cap) to blow the resistor to smitherines. To heck with melting things.

Well Dave, the graph of temperature change vs power is counterintuitive. Heat dissipation is highly nonlinear process, so I guess .1W -> 10K change, and .2W->less then 20K rise. So why the heck the graph is linear ?

[@emactan]

Simple and creative. By the way isn't fishing line made of nylon?

[@ivanv754]

5:40 I knew he was not going to end the video just yet.

[@alfonsoskid]

you toasted that poor innocent 10ohm resistor :(

[@rich1051414]

why not just short out some thin filament? I assume this demonstration was purely for educational purpose? Burning a resister to set off a thermal trigger is totally unnecessary and superfluous :P

[@djdutcher74]

Man the mice must be big in Australia!

[@jnrolf]

@ib9rt Come again??? The DeltaT(K) in this case is a function of Watts... so how did you get the Celsius to equal the K?

[@jnrolf]

@ib9rt Thanks for the reply... Mmmmmm but? How do you calculate that 1:1 ratio @ib9rt? Give us a working example/formula on how 35K is equal to 35C or 140K=140C. A web site on this would help us?

[@THEmilehighclubber]

Killing vermin, like a boss. Nice one Dave :)

[@RussellValentine]

How can you do this will low power? Is it possible to find something that will run on 10mW that creates quite a bit of heat? It seems hard to search for resistors based on thermal resistance. Are there things better than resistors if you are wanting to repeatable generation of heat?

[@f-s-r]

What about muscle wire to trigger the mechanism?

[@EEVblog]

@JasonLikesCake Ramen!

[@jan.tichavsky]

@EEVblog Yeah, but degrees Kelvins isn't about English but about physics :-P

[@Bodo.berlin]

Hey, watch again the exact minute when Dave said this. He saw ΔT, so actually he missed this cute litte the greek character "delta" in this moment. I'm know Dave know both as he insisted on "degree Celsius/Fahrenheit, but just Kelvin!" in other episode(s). So ParadigmicShift and Jan, share YOUR video with us so we can enjoy YOUR black-outs with a smile. On trying to do so you will find the amount of hours such episodes take to produce. Lean back, enjoy, have a little chuckle yourself. ;-) peace

[@sourcesource8750]

Can you pls design good mosquito trap, Basically integrating with door mesh. Many ppl try to make lures but forget that humans are biggest lure, they definitely try to enter house and if mesh is designed to electrocute them that would be great. Design should be good enough that mesh won’t give shock to humans

[@EEVblog]

@alfonsoskid It was begging for it!

[@douggale5962]

Complete with magic smoke. I bet that resistor had plenty of magic left in it though.

[@extremespaghett1107]

You can burn the thread with arcs

[@Minifig666]

@EEVblog Yeah, one that has stopped existing!

[@TheCrazyInventor]

A mouse trap...? Holy crap, that's a bear trap. :| Interesting video, though... Nothing like the usual stuff over here.

[@gunnarfroberg2060]

Kelvin, not degrees Kelvin.

[@myozone]

This how they deploy antennas on software satellites !

[@kcj1993]

Yay! I learnt something.

[@goodash1]

@taz069 I think it might be for kangaroos.

[@jnrolf]

35 kelvin = -238.15 degrees Celsius 35 degrees Celsius = 308.15 kelvin

[@jnrolf]

@MrParegorico Many thanks @MrParegorico all clear now ;)

[@skuula]

just have the usual latch on the trap triggered by a solenoid.

[@doodh_jalebi]

In Australia TEMP in summer outside = 30C In Pakistan TEMP in summer outside = 50C!

[@ufo.architect]

Leave the mice alone, unless you are going to eat them, A

[@ZeddysZ]

Myth Confirmed.

[@TheMysteriousProduct]

@axel1973w Too Dangerous?? Electronic parts get extremely hot in working devices all the time. You wouldn't want to set up hot electrical components in a pile of sawdust but with a little planning there is nothing to worry about.

[@javedkhan0258]

consumers dont know about resistor. to load again u need one more resistor! bad design lol

[@ParadigmaticShift]

Love the videos but I cringe when I hear "degrees Kelvin". There are degrees Celsius, there are degrees Fahrenheit, but there is NO degrees Kelvin, its just called Kelvin. FSM FTW!!!

[@taz069]

Holy crap, is that a mousetrap or a cat trap??

[@jnrolf]

@ib9rt Many thanks @ib9rt all clear now ;)

[@sfbox]

why not then rather take a nichrome wire....

[@tagno25]

Nicrome would probably work better

[@ArtCarb]

@jnrolf ..hi put some numbers in the formula so you get it...

[@mymixxed]

Who was watching the ant at 4:10?

[@ArtCarb]

here is an explanation

[@ParosPasxaRide]

just use a battery with a relay! very bad design disappointed on this one!

[@Ozziepeck11]

how would a relay trigger a mouse trap exactly?

[@Bdix1256]

wax motor

[@InsurgentX]

Second! (or so...)

[@tw34kd]

First! lol

[@rainbowsalads]

evil devices , imagine falling into that trap when you are small. how long it would take to die . FFS. design a humane system or design your building correctly. A trap wont stop the flow of rats, block the holes where they enter. peace.