If you can wait a couple weeks, AliExpress is going to be the cheapest.

eBay may be a bit more expensive, but it’s often my go-to because you can find everything and usually there are options with short shipping times.

For not too obscure parts, I would look at Reichelt, their prices are surprisingly low (especially if you bundle your orders to save on shipping costs).

HiPER Calc Pro. A great scientific calculator I use constantly. (There is also a unpaid, ad-supported version, and the ads weren’t too intrusive the last time I tried it)

That’s probably not a bad idea, although I doubt it will make much of a difference. But since you’re redesigning the whole thing, might as well do it.

It looks like you would want an even airflow through the whole PSU. The main heat-generating components are using the sides of the housing as a heat sink. I’m guessing the fan is mostly so the air inside the housing doesn’t get too warm, not to cool individual components.

Where is the original air exhaust? If it’s near the bottom of the picture, that would confirm my theory. In that case, I would keep the fan placement as close to original as possible (i.e. the blue square).

You can use a boost converter to boost the 5V of an USB port to the 19V your notebook needs.

Assuming 5A output from a powerbank (which is probably about the max you will get without USB PD), you could theoretically get 0.55A at 19V. With the unavoidable inefficiencies, you will get less.

So, maybe enough to very slowly charge your notebook while it’s off. But when it’s turned on, the battery charge will still drop.

From a cursory read of the datasheet, using the “dead time control” pin seems to be the way to go. Basically, this pin is used to set the voltage, while the error amplifier inputs (that’s the closest function to “over current protection” this chip has) are used to adjust the output according to the load. For your application, you probably don’t need to use them at all.

My instinct would be to disable the error amplifiers by connecting pins 1,2,15 and 16 to GND. You can then connect the wiper pin of the potentiometer to the deadtime control input, with the other pins of the potentiometer connected to GND and 3.3 V.

I haven’t worked with this chip before, so take this with a grain of salt. You should probably use a simulation tool to check the circuit before you start destroying chips.

My router is called Jupiter, everything connected to it is named after a moon. Callisto, Ganymede, Thelxinoe, Kallichore are what I’m currently using.

That’s why I don’t let every device decide individually. I know my router (FritzBox) prioritizes the pi-hole (it’s even called “preferred” and “alternative” DNS-Server in the UI)

I have my pi-hole setup as the upstream DNS in my router, with cloudflare as a secondary DNS. That way, all my devices always use the router for DNS (since that’s what is advertised in my DHCP) and the router then uses pi-hole if it’s available, or cloudflare if it isn’t. But the individual device doesn’t get to choose between different servers.

I’m guessing it’s about documenting the assembly of safety-critical components. If some part of, let’s say an airplane fails because a bolt comes loose, the manufacturer wants to have a paper trail attached to it to prove that this specific bolt was indeed torqued to the correct spec. Connecting the wrench to the network could make this documentation much easier.

Matlab

Those adapters should definitely be fine for 24 V. Running the fans off 19 V will probably work, but they will run at slightly slower RPM (probably not a big problem for a filter).

You could use a voltage divider followed by a unity-gain amplifier to lower the output impedance, about like this: (I think that circuit could work, but I haven’t thought about it a lot, so it might not)

Not really. With that bulb, all the light is focused forward, not to the side. The light will never hit the reflector, it is only focused by the lens in the LED housing, and that isn’t enough.

From looking at the LED bulb, I can tell you that it will not work very well in that flashlight.

The reflector of the flashlight is built so light coming from a very small source (like the filament of an incandescent bulb) is directed forward in a focused beam. With the led bulb, light is coming from 10 different spots, none of them being in the focus point of the reflector. The result will be a spread out beam that won’t be bright over longer distances.

The only type of LED bulb that could work is something like this car replacement bulb that keeps the light source to a relatively small spot. But I don’t think those are available in the size you need.

It isn’t that hard, But it might be a bit overwhelming if you haven’t done something like it before. I would recommend setting aside a couple of evenings for the job and taking your time. Start by stripping everything down, the build your bike back up slowly with the new parts.

It might be easier to pay your LBS for the job, but if you do it yourself, you are going to be well equipped to handle most issues and do any maintenance that may arise in the future.

Also, you can always bring the bike in to your LBS for the final setup and adjustment.

Here are some things you might want to keep in mind/check:

• if you are replacing brake/shift levers, you will need to rewrap the bar tape. It might be possible to reuse the old tape, but it might get destroyed in the process. (In my opinion, just get new bar tape. It’s not that expensive and directly impacts the (literal) feel of the bike
• different types of bottom brackets need different tools. Check that you have the correct one before taking everything apart.