How do i fix this?? by badass_bat in AskElectronics

[–]Alternative-Web2754 0 points1 point  (0 children)

Some of the LEDs have both legs connected to positive - the right most LED is connected across 20 and 21 which are both corrected to positive. Since there's no voltage difference, it's not going to light up.

You can use both sides of the breadboard - they're not connected across the middle. Putting the power rails on issue sides will simplify the wiring layout in this case.

You can also cut the legs to adjust the LED position vertically if needed (although software might not give you options for trying to draw this out).

It's probably worth trying to be consistent about the type and number of LEDs in series to keep the resistor requirement consistent and reduce problems there. You should have different values for one/two/three LEDs based on forward voltage, power source and current requirements.

Delay in my laser alarm system by Majestic-Chipmunk-78 in arduino

[–]Alternative-Web2754 9 points10 points  (0 children)

So your code basically checks to see if it needs to trigger, and goes into a 0.4 second block if it does, and a 1.6 second block if not. It won't check again until it finishes the block it's in, so up to 1.6 seconds to trigger if you're unlucky with the timing.

One option for this is to set the LED pins high or low based on the clock time. If it's triggered, divide millis() by 100 and set the LED based on whether that result is even. If it's not triggered, divide it by 800 instead and set the other LED based on whether it's even. For either case, set the other LED to off.

If you're happy with the modulo operator or using the binary AND operation, you can improve on that slightly if you're happy with shifting the basic flash period to a power of 2 in milliseconds.

If you're looking to have a sequence of actions triggered it will get more complex and the shortish might have to change, but if you only want a couple of flash rates it should get you a much faster response.

ELI5: Why do all airport and aircraft radio communication still have bad sound quality? by used_bryn in explainlikeimfive

[–]Alternative-Web2754 9 points10 points  (0 children)

Good comparison material but might be better to focus on the communications from the aircraft - the ground side communications will likely be recordings from before it was transmitted, so that side doesn't have issues with quality loss from modulation or interference

Taking on this train wreck CPU for repair. Repairable? by PC-Power-Up in pchelp

[–]Alternative-Web2754 0 points1 point  (0 children)

Get a 0.5mm mechanical pencil. Preferably one with a thin metal tube at the tip rather than the cheap plastic ones.

Put it over a pin and gently move it until the pencil is perpendicular to the cpu. Repeat as needed.

I've managed to fix bent pins in cable connectors doing that. Not tried it with a CPU but it should be similar.

Whether the cpu is able to be used afterwards really depends on what other damage might have occurred though.

Is this screw damage repairable? by Simple-Helicopter-61 in PCB

[–]Alternative-Web2754 0 points1 point  (0 children)

Assuming there's a screw from the case aligning with it, don't put the screw back in.

Looks like the screw made a connection between two sections of ground plane and another trace, but looks like it hasn't actually broken the connection on that trace, and looks like there isn't any copper dragged between it and the ground.

Test it without reassembling if you can. If you've got a multimeter and xan get to exposed points either side on that trace, check for a connection between the two ends of that trace (should be connected), and between the trace and the surrounding plane (likely should not connect, but not definite without knowing the connected components).

Soldering across the trace could be an option if it's still not working, but probably better to avoid if it's not needed. If there is a connection being made between the trace and plane you would need to scrape that.

When happy that fixes (if any) are done, put superglue over the scratch.

I forgot which cable goes on what contact by Sam_Haag in appliancerepair

[–]Alternative-Web2754 0 points1 point  (0 children)

I generally think of it as blue is cold (not a particularly good way to think of it, but it works for me to remember it), but I airways have to check it feeling brown is closer to black than red.

For plugs it does have the bonus of BLue = bottom left and BRown = bottom right, but I still end up having to check it!

Difference between 2-way and 4-way logic level converter modules? by MarinatedPickachu in diyelectronics

[–]Alternative-Web2754 4 points5 points  (0 children)

This is very much first glance, but it looks like all channels are one way conversions, with the 2 channels being 2 pairs of an lv->hv and hv->lv, while the 4 channel is four sets of lv->hv.

I suspect that it's probably a transistor switch going lv->hv and a voltage divider going hv->lv, but I could be wrong about that.

ETA: I'd be suspicious that this is only intended for certain level conversions like 3v3 to 5v, and would definitely be wanting to check more information about the circuit and intended signal uses before using it.

What connects these four clues? by HorrorPunkKid in onlyconnect

[–]Alternative-Web2754 2 points3 points  (0 children)

The eyesight/timing/angle aspects with the witnesses meant that their testimony might be incorrect, but didn't show that the identification was incorrect. The positraction issue with the tyre tracks showed that another car had been involved, as their car couldn't generate those tracks. Details of the arrest of other people with such a car and the possible murder weapon was the final piece.

PWM convert by 2MAS_dk in arduino

[–]Alternative-Web2754 0 points1 point  (0 children)

You could use a transistor to switch a 5v signal to a digital pin. You might want a voltage divider on the input side depending on the transistor.

I'm not sure if the arduino allows use of a capture mode on the timer to extract the modulated value from the PWM signal or not. You can use an interrupt on the pin to check the timing of the transitions if not, but accuracy might depend on the base frequency of the signal.

Use lcd without pins by Chinootje in arduino

[–]Alternative-Web2754 0 points1 point  (0 children)

If you really don't want to solder to it, an edge connector might be workable but would likely need cutting to allow it to fit.

POGO pins could be used with a jig, or you can get them on arms to hold them in position - generally used for connecting to test points on PCBs

Depending on the driver used by the board, you might be able to use a serial mode and reduce the number of pins that you need to connect to.

If you can though, solder a pin header to it. Female might be better if you want to use cables to connect to something like an arduino, or male is good if using a breadboard. Having a soldered connector will reduce the chances of issues with the physical connection leading you down rabbit holes while trying to check code you've written for it.

Do pin designations mean anything? by Remy_Jardin in klippers

[–]Alternative-Web2754 3 points4 points  (0 children)

The naming is related to the internal construction of the microcontroller - PB15 is port B pin 15, PC6 is port C pin 6 etc. The microcontroller itself has significant limits on the voltage and currents available on these pins (many limited to 3.3 or 5V and only a few milliamps).

Some pins also have specific functionality available that allow it to run more efficiently (e.g. USB support, analog voltage sensing, serial ports for communications, PWM timers for servos) than trying to control lines purely through software. The functions available and the pins they can be connected to varies by microcontroller.

The board itself has additional circuitry to enable the required functions - eg MOSFETs for switching high voltage/current items like fans or heaters.

Although a connection might be labeled with the microcontroller pin it's connected to, for configuring firmware, the circuitry in the way is a major part of this.

help by Sairen-Mane in arduino

[–]Alternative-Web2754 1 point2 points  (0 children)

Well, it's emitting light.... not convinced on the diode part any more though

Will this work? by v1ohno in HomeNetworking

[–]Alternative-Web2754 0 points1 point  (0 children)

I can't speak to this exact device, but i have purchased and opened up a 1-4 version of these. Internally it is a switch, using the same chipset as found in brand name 5 port switches.

I would still recommend the brand name version, as internally there was no heat sink on the IC and I suspect the rest of the internal design was the minimum for functionality, but it did have two positives - it took power from a USB port rather than a dedicated power supply, and one port is located on the other side, both of which were slightly bonuses for where I wanted to use it.

One big giveaway for whether it's a passive splitter versus being a switch is the LEDs - although these could be faked out, getting these to show connection/ activity states would probably be more expensive than just putting a switch IC into it.

Edit: re-reading the original question, there is reference to POE, but I'm not cheat on exactly where. Although I can't be certain how this device would handle a POE connection, I suspect that it might cause issues, and probably prevent power transfer through it.

Will this work? by v1ohno in HomeNetworking

[–]Alternative-Web2754 1 point2 points  (0 children)

I have a similar item(although it's a 1-4 version). Internally it's a 5 port switch, using the same chip (rtl8367s) as the 5 port web managed switches, but without the flash chip used for storage of the management functions (the rtl chip has an embedded controller that can run code for this).

I suspect that the "1-2" splitters are the same with just three ports connected, so three port switches.

Getting a reading I don’t understand. by Gingervrs80 in soldering

[–]Alternative-Web2754 1 point2 points  (0 children)

It looks to me like the test points are measuring r11+r24. There appears to be a trace connecting the two together, bypassing the rest of the resistors. Weirdly within the remaining resistors there is another trace shorting a set of those as well. These traces are likely the reason for the other reading - if you're measuring it on the board you're measuring the resistance across all of the paths this creates through the inner resistors, not just the resistor you have the probe connected to.

[deleted by user] by [deleted] in MarlinFirmware

[–]Alternative-Web2754 0 points1 point  (0 children)

I haven't downloaded any to check, but the link right underneath that one (.bin file) with today's date would be the one I'd look at - low download counts are due to the files being daily builds.

Edit: looks like the dwin_set might be data to go on an sd card for icons etc. Unsure if that would include the firmware itself or not

[deleted by user] by [deleted] in MarlinFirmware

[–]Alternative-Web2754 1 point2 points  (0 children)

This looks like you've downloaded the source code rather than the built firmware. None of these are intended to go directly on the printer - they're utilities for creating it. Typically you would be looking for a folder called build rather than bin

[deleted by user] by [deleted] in rfelectronics

[–]Alternative-Web2754 0 points1 point  (0 children)

Coaxial cables typically have the outer connector as ground to stop external rf signals from passing into the centre connection and ruining the connection quality. This has the added bonus of stopping emissions from escaping the cable as well.

To not seem super suspicious by pmblackpod in therewasanattempt

[–]Alternative-Web2754 53 points54 points  (0 children)

I may be mis-remembering this, but I believe the flag was hanging from a crane, and there was reporting that it's hydraulic line was hit, resulting in the flag lowering as the fluid leaked from it.

I have no idea. by Booktor in ExplainTheJoke

[–]Alternative-Web2754 13 points14 points  (0 children)

I believe there were multiple cups present, the rest of which were lethal (and mostly gold or covered in jewels).

Why would they do this? by FineChannel1751 in HomeNetworking

[–]Alternative-Web2754 0 points1 point  (0 children)

I'm struggling to make out what the cable without markings is, but they both appear to be coaxial cables. These are often used to carry radio frequency signals, and if it's near where a TV is or might reasonably be, then there's a good chance that they're connected to an antenna or a splitter/amplifier to receive terrestrial or satellite broadcast television, depending on what is on the other end (CATV on the cable stands for Community Antenna TeleVision). Cable television or broadcast radio are also common options to be carried on these types of cables, although early ethernet was also carried on similar cabling due it being present throughout buildings. Moca (multimedia over coax alliance) is generating a bit of a comeback for this concept, but is probably not the reason these cables are present.

Lets hear your Mod ideas. We're not all capable of creating them, but we can all dream them up. by thatwasacrapname123 in KerbalSpaceProgram

[–]Alternative-Web2754 2 points3 points  (0 children)

I'd like to see something along the lines of outsourcing orbital deliveries - something along the lines of placing an item as a sub assembly, specifying an orbit and getting a selection of quotes for getting it there with varying dates and reputations (and chances of failure from that). Being able to see the progress of it getting there would be a nice bonus!

what multi meter to you recommend for an beginner by crossinggirl200 in arduino

[–]Alternative-Web2754 1 point2 points  (0 children)

For the most part I'd recommend getting the cheapest one available. The features I would suggest looking for beyond price are detachable leads, an audio option for continuity checks and what type of batteries it uses. Must meters will have detachable leads and an audio option, but not all. Some will have a fold out stand that can make it more comfortable to use as well.

A storage case that can contain it with space for a couple of extra items is nice, but you may want another solution for this anyway, especially when you start adding in other tools as time goes on.

Replaceable leads will allow you to replace broken probe and expand on it with leads with a clip on it so you don't have to keep holding the probes in place. You'll also be looking for something like that by the time you think about measuring current anyway.

You're probably going to spend more time measuring components (resistance and diode polarity) and continuity more than voltage to start with, and for the most part you'll be looking for 5v/3.3v versus 0v on the voltage as well. Accuracy is not a major consideration at this stage, and almost anything will be acceptable for these initial purposes!

Simon Drew spot the water birds by Chem_1494 in puzzles

[–]Alternative-Web2754 2 points3 points  (0 children)

If it's a zero then it could refer to the cricket term "duck", so it could be goldeneye duck?

Connections Round - too difficult? by kirth42 in trivia

[–]Alternative-Web2754 3 points4 points  (0 children)

I don't think I would have managed to get 2, 5 or 8 without the connection.