# Muscle-wire cabinet lock ## Метаданные - **Канал:** bigclivedotcom - **YouTube:** https://www.youtube.com/watch?v=88wovqfuu94 - **Дата:** 22.05.2026 - **Длительность:** 6:10 - **Просмотры:** 30,872 ## Описание A very odd little thing. I initially thought that this was based on a magnetic latching system, but it turns out that it uses a length of a special wire that contracts significantly as it heats up. It means that this unit is very simple with a minimum of mechanical parts and is not influenced by a string external magnetic field as some magnetic units are. The wire is theoretically rated for millions of cycles with this small controlled movement. Although rated for a higher voltage, I tested this with 1V to slow down the actuator movement. The electrical data at 1V is: Cold resistance 2.86 ohms (350mA at 1V). Hot resistance 2.5 ohms (400mA at 1V). The unit is normally rated for 3 to 5V. The unit only energises the wire for the length of time it takes to release the catch, as there is a switch inline with the muscle wire. As with many items I've been buying recently, this one came from AliExpress (not a sponsor) Here's a non affiliate link to the listing. https://www.aliexpress.com/item/1005005211494161.html The cost should be around £2.50, and it may appear as a bundle deal item. If you enjoy my videos, supporting the channel on Patreon helps keep it independent of YouTube's quirks, avoids intrusive mid-video adverts, gives early access, bonus footage and regular quiet Patreon live streams. https://www.patreon.com/bigclive Alternatively, for a single coffee contribution you can use PayPal:- https://www.paypal.com/paypalme/bigclive #ElectronicsCreators ## Содержание ### [0:00](https://www.youtube.com/watch?v=88wovqfuu94) Segment 1 (00:00 - 05:00) In a recent unbagging video, I featured this interesting little lock device. I shall zoom down it because it's very small. And this lock is a classic little automatic release locker sort of thing. You know the Amazon lockers that you when the doors are closed with your package inside and then when it's signaled, it pops open, the door flies open, and you can take the package out. And I thought this was magnetic, but someone mentioned it's probably based on muscle wire. And that's got advantages because it means it's less like to be affected by a magnet. So, I powered this up at low voltage, much lower than it's intended for, 1 volt. And watch this. I'll give you a close-up of this because it's very subtle. Watch this little lever here slowly move down until that pings and releases. And this is currently set to 1 volt at 386 milliamps. Let's try that again. So, if I push this in, it automatically disconnects when the thing flies out. But if I push this in, after a small delay, you'll see that slowly creep down until it pings out and then that relaxes and goes back again because it's got a switch inside. That's interesting. Um, let's grab a big magnet and see how that affects it. So, with a huge neodym, you don't get the usual sound you get from the electromagnetic ones. And the only thing that's going to really be attracted to this is the actual the hasp itself. Oh, that's actually still on. I shall just turn that off so it doesn't automatic release. So if I push this in, if I hold the magnet, it I'm going to have to hold that clasp out the way here. But if I hold the magnet in various positions around this, it doesn't seem to release it. The only way you can release it other than electrically is by pulling this little catch down manually, which is the sort of safety release mechanism. Right, I shall put this magnet out the way and then we can unscrew this cover and take a look inside. Oh, before I do that, I shall turn the power supply up to 5 volts, which is more or less what it's rated. I think the current's going to be quite high at that, though. And I shall turn the power supply off. Pop this in. We'll see how fast it actuates at 5 vol power. Oh, straight away it instantly uh releases at 5 volts. That's what was making me think it was magnetic. But that's really fast. That's interesting. Okie dokie. Off goes the power. I shall put the crocodile clips out the way here. Or allocator clips if you prefer. Grab a screwdriver and hopefully it won't ping into millions of bits when I open it. It may ping into millions of bits. We'll find out when I undo the screws. It does seem to have little strengthening pins through here, which are also the ones used to anchor it to the case, presumably. Okay. Is this going to be destructive? Oh, it's not willingly opening. Oh, it is under a bit of pressure. Oh, here we go. Right. Tell you what, I shall take a picture of this so we can see it in greater detail. Okay, let's explore. And this is some interesting features. Initially I saw these little metal bushes and I thought they were for strength just to give it, you know, mechanical strength for the fixings. But it turns out they're effectively little guides and also sort of heat shields the plastic because the wire that actually actuates it is this wire here. This is it in its locked state at the moment. The latch has been pushed in and it's clicked over that little pole there. And when you power it up, the current flows through the wire and which travels around here over to here and then to this connection and then it goes via this switch which is in this uh position sticking out the way. It's closed, but that powers the wire. It contracts, pulls this uh latch back, clicks that out, and uh that then pushes the switch in and disconnects the power to the wire so it doesn't keep heating. And I measured it and with one volt with the wire cold it was passing 350 milliamps which equates to 2. 86 ohms when it was hot. And I just I bypassed the switch and let it heat up to the point that this it traveled to its full excretion which was basically just short of going into here. And the current increased to 400 milliamps at 1 volt which equates to 2. 5 ohms. So as it shrinks it does of course get fatter I'm guessing. and uh its resistance lowers. Now, this is it uh in its locked state. And it's not notable that there's a spring in here that normally biases this latch, the pole, in that direction. And there's also a spring in here that biases this in that direction. So that when this actually pulls back, that clicks down with enough force to actually ping this out and knock the door open. If we take a look at the ### [5:00](https://www.youtube.com/watch?v=88wovqfuu94&t=300s) Segment 2 (05:00 - 06:00) actuated position, we can see that it's pulled back and released that and that has clicked down into its uh fully open position, allowing the latch to get pushed back in again. And also, it's activated that switch, which has disconnected power to the heater. It's very interesting. I will say that um these are the two holes that were used to put the cover on with selftappers, but I think for the other positions, you'd need to probably use little machine screws or something to lock this in place because you couldn't really uh risk putting a thick selftapper in here and actually sort of spraying the plastic out. Although they've done it in that one, haven't they? Um but probably better with just basically nuts and bolts as opposed to selftappers. But there we have it. It's interesting seeing such a simple mechanism of using this Titan muscle wire stuff. Um, it does make things somewhat simpler than the solenoid activated mechanisms. And of course, there's no major steel in here to be affected by a magnet as well. So, it's very clever, very neat design. --- *Источник: https://ekstraktznaniy.ru/video/51797*