An aquarium pump from ebay and there's two things that caught my attention about this one is the rather nice clear case. Let me just shine a light into this, so you can actually see the effect here that it is quite nice inside it looks very technical. It also has a little switch on the side that lets. You choose two settings and i wondered how they implemented.

That is it going to be a capacitor tap in the uh magnet, or is it going to be a capacitor in the series, as they sometimes do, so this unit is called an sb-990? I can't remember how much it cost it wasn't that expensive, but probably grossly exaggerated that here output as they do, let's plug it in so i've got the hoppy here and we'll plug it in now and we'll put down this little rubber feet, um about 3.8 watts. 17 milliamps 0.9 power factor. Let's change that little switch to the side, much quieter! It goes down to about half two watts: 10 milliamps and 0.7 power factor. Okay, let's take it apart, screwdriver.

My guess is that, just because uh, it's probably the cheapest way to do it, i'm not actually sure if that would affect it a diode. Maybe that would affect the way that magnets, spun i'll show you what that's like when it's open i'll run it when it's open, that's the best bet, assuming it doesn't all just completely fall into bits. That is just trim. Oh, it looks nicer without the trim.

Oh any hidden, fixings, oh, i have a sneaky feeling. This thing is going to stop it coming out right. Tell you what i'll just use brute force and ignorance? Oh there we go, does that? Oh, it does pop out right. Okay, that's useful to know here is: what's inside two connections going to the transformer and there's a diode across the switch.

So all it's doing is it's switching between direct power and going through the diode? So, let's see what it looks like when we switch it between the two, so that's currently in its diode setting and that little thing i'll zoom down this, it's uh showing you in slow motion, which is quite nice because uh the camera frame speed, is actually different To the main frequency, so it's uh, showing you a slow-motion effect. Let's turn this off so that i've got a wall up. Uh turn that on to the full setting. Oh blame me: let's just uh gingerly hold it like this.

It's uh! It doesn't really. If i thought it might affect the direction that thing swung um in the sense, what normally happens to these the trans, the transformer? Well, it's up, it is almost like a transform, but the magnet electromagnet here uh attracts repels this magnet and as it does so, it basically pushes the diaphragm the pump. Let's see if we can get this out and take a look in here, this is going to slide out. I think it's got a little rubber bung is that kind of secured in it it's kind of secured in it's going to come out.

Also, this is secured at the back here. Let's take it all to bits, that's what we do here. Oh actually, you know what it's uh, it's showing secrets already. That's quite interesting, but i'd say well.

I shall lift this up here. It comes so we've got a diaphragm at the back and a little chamber, and there is the one-way valve. There's two one-way valves: oh and they're little bungs. Now let me see if i can get you get you close to this.

I shall focus onto this and we'll zoom closer like this and i'll show you with a bit of light uh. Can you see the little flap there that they've, just bunged in they've, actually just jammed in with the rubber plate? And likewise, if you look at the other side there, you can see the uh the other side of that other flap, which is also just trapped in that is very, very simple way of making things. I feel the need to remove one of those little rubber, bungs and see what the construction is like. It is just a little rubber bone and is it a loose rubber flap? Yes, it is just a very simple super thin rubber flap uh placed in there like that, and then a rubber bung jammed in just to hold it in place like that.

If that was the right way around and squished down, that's reasonable enough and to seal the other side of it, just because it's just to make it as simple as possible. One side is that pumping diaphragm with the magnet swinging to actually pump it um and the other side is just pressed against this rubber plate here to seal it. That is very interesting. Let's put it back down there, and so that's it.

It's the little. It's the standard thing that you find in these i've noticed uh, there's another one somewhere i have misplaced and uh they seem to adjust. They seem to use a standard coil in some models that may even be universal for 120 volts, but then, in the same, the european ones, the 222 3240. They actually put a capacitor and sears the coil and that's how they use just one coil for them all.

That's also a technique used in some time switches where they put a resistance. Here's the coil - and it just means they can use a a cheaper coil, possibly a coarser round one, but that's quite interesting, nice construction. I do like the clear case that makes it kind of appealing when you can see stuff inside. So that's what these uh pumps are like inside.

Very simple construction and the air outlet adjustment is simply a diode in the sears of that, so that it only operates at about half power.