True AC is sort of “balanced” in that it has just as much positive as negative. The positive area of the waveform is the same size as the negative area. For waveforms that are sort of symmetric across the 0V with a time offset, such as a sine or square wave, this means that it is centered along the 0V line. A DC source, on the other hand, never changes voltage.
The 0V to +10V source you have is actually a -5V to +5V square AC plus a +5V DC. The capacitor is getting rid of the DC component leaving just the AC, which happens to be the -5V to +5V AC that you are getting.
That’s why they call it a decoupling capacitor, cuz you usually just need AC (signal) at the out of a circuit, you don’t need the DC part of the signal.
pressfit connections usually are very reliable. if there is a poor connection i would presume that the barrel of the via is broken and a new pressfit connector will not help. maybe putting solder in would help. did you already test for poor connections?
Barrel of the via? I’m unfamiliar with that terminology – what is that? I did a continuity check from the very bottom to the very top and everything tested good. When the audio is out, twisting the header a bit would usually bring it back so I assume(d) it was just a poor connection somewhere despite the continuity check.
EDIT: Okay, some quick Googling got me understanding this better. As I mentioned, continuity is good, but I still suspect it’s something in this area. I suppose I could remove the connectors and install solder connectors, instead of press fit?
yes i think so, but u would have to make sure the solder will rise through the through-hole as mich as possible. maybe u can try to find the faulty pin with wiggling them separately
The standard way of looking at this is to consider a capacitor-resistor series combination going to ground. Connect a 10v (wrt ground) supply to the capacitor and the voltage across the resistor rises to +10v, then decays. Now connect that capacitor to ground and that same resistor gets -10v across it, which then decays. Whatever is connected to the capacitor “top” terminal has to be able to sink current as well as source it.
That’s what generators in simulators do - they have zero internal impedance (usually). They sink currents as well as source them.
The fundamental concept at work in making an electromagnet is Lenz’s law. Here’s a Khan academy video on the topic. www.youtube.com/watch?v=xxZenoBs2Pg
You can determine the power of a magnet (very roughly) using the following equation:
B = μ₀ * n * I
Where:
B is the magnetic field strength in teslas (T) or gauss (G). μ₀ is the permeability of free space, approximately equal to 4π × 10^-7 T·m/A. n is the number of turns per unit length of the coil (turns per meter). I is the current flowing through the coil in amperes (A).
So the number of turns matters, and also the current matters.
But there’s a third thing, and I think that’s the problem you’re having: This piece of wire is conductive, and the nail is conductive, and there doesn’t seem to be any insulation on the wire. Because of that, the current flows through the wire on one side, into the nail and across it, then out the wire on the other side. The current needs to flow in loops without being able to take any other path, The coil of wire and the current flowing around in circles is what’s required.
What you want is a long piece of wire with insulation on it. Then you wrap it around the nail, and then apply a battery across the wire. A 1.5V battery probably won’t have much punch so you might not be able to get much of a magnet, but a 9V battery should do it quite well. What will happen is the current flowing through the wire will create a magnetic field, which will magnetize the nail, which will create a magnet you can use to pick up coins.
A lot of the time, people run demos using special wire for creating magnets that’s copper with a very thin clear insulating coating on it, so you might think you’re looking at someone just making a loop of regular wire, but the insulation is key to the whole thing working.
In my experience a large 1.5v D cell works best, as the limiting factor is generally current not coil resistance, unless you wind thousands of turns of fine wire.
Maybe give the tool and helmet a white outline too: easier identifiable
and another idea would be to mix into the question mark an electrical spark but that are only some random tired ideas.
That are like the only things i found to edit, not sure if it is improvement
I’d suggest peeling off just one strand of the wire and use that. You will need to insulate the wire from the nail - Wrapping paper around the nail will do. You will need to insulate the wire from itself, so that adjacent turns don’t touch. You can just space the turns out along the paper sleeve. That should do the trick. If you have twine, you can wind that on with the copper wire and use the twine to keep the turns from touching each other.
Oh to straighten copper wire, if you don’t know this trick - hold your nail in a vice and wrap a single turn of copper wire around it. If you then pull on one end of the wire, keeping a little tension on the other - with a bit of practice it will give you a very straight end result, as the wire pulls away from the nail.
My local children museum has something like this. Let me see if I can find a picture to give you an idea of the set up. It does look like it would be $$$ for set up. What’s your price point?
Cool! I’m still looking for a picture. I’ll post when I find it but thinking about this more I know there are a ton of toys like this made. Most are for older kids and are priced at about $20-80.
Look up circuit station kids science and you should get an idea of the kits.
My kids had Snap Circuits but it’s a bit complex for a toddler. It’s probably the most basic circuit designer I can think of though. They did a great job. If an adult is helping it would be fun for both.
Yeah around three they should be able to do it with adult supervision but it’s still a bit of a toss up on if they are going to put the small parts in their mouth. I can’t find the a good photo of the big one at my local children museum. It’s going to drive me crazy. I’ll probably just have to take a picture next time I go in.
Breadboard is a cool idea, but your first experiments will likely be super simple right?
Here’s a few thoughts.
How about some double conducting copper tape and sheets of craft paper or cardboard. (Double conducting conducts on the top as well as the sticky side so overlapping joins completes the circuit).
You can draw/plan and then route the copper sticky tape like a circuit board. Fashion basic switches from the copper tape around a cardboard flap, tape down any “flat” components like resistors.
Add some tinned leads to anything that would stick up from the board.
I often find the more tactile “MacGyver” approach is a better teaching aid as there’s no mystery behind the scenes (no hidden board wires, no pre-mounted components or connectors). Everything is built up from existing skills and experiences.
When you start to get more advanced, 80s Aussie kids grew up with:
That has a complete list of components needed for the projects in the book. Same idea as the copper tape, just with bits of wire and screws. The project in the book were all built onto a pre-drilled block of plastic with the schematic laid on top. They were fun little projects and easy enough to do - the flashers and sirens were a hit for me.
I really like the cardboard approach. Maybe I can come up with something on a plywood basis. Copper tape is a great idea. Also thanks for the link, I imagined something like this just a little bigger and sturdier and with more basic components (resistors included with the LED for example). Will save the book for later.
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