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3:34 AM
@JRE Could you run a waveform simulation on a connection via 2 seperate outlets to get 240-250 VAC RMS?
@JRE 2 circuits. Both 123 VAC RMS. I want to connect the earth ground (neutral) wire to another earth ground wire. Then a black (live or positive) wire to another positive. I'll draw a circuit diagram to help.
@JRE Here is the circuit diagram.
@JRE I know the earthed ground wire is connected to the negative cycle or side of the sine waveform. So the neutral is the ground wire. Which means they are at a zero potential. So I'm taking advantage of that. I'm taking the neutral/grounded wire as a ground wire. Then using the 2 same phases on the hot or positive wires to power the 20 Amp 240-250 volt outlet.
@JRE My theoretical educated guess says it'll work, but a part of me says it may skip a cycle. Will it slip a cycle?
@JRE The separate neutral wire is never connected. Just the ground/neutral and the hot (positive) wire are connected.
 
 
2 hours later…
JRE
5:40 AM
@ScientistSmithYT There's not much point in a "waveform simulation." If the two outlets are really on separate circuits (completely unrelated to each other,) then there's no telling how the phases are related. Anything from "boom" when you connect the neutrals to "works like you imagined" is possible
If you need 230VAC, then go back to the fuse box. If you have 120VAC , then there's 230VAC available in the fuse box. An electrician can run a line and install a proper outlet for you.
Two hot wires and a neutral enter the home. From hot wire to hot wire you have 240VAC. From either hot to neutral is 120VAC.
 
JRE
6:16 AM
Oh. If you do manage to connect two 120VAC outlets to get 240VAC, then do NOT use a 120VAC outlet to plug your devices into the 240VAC. Get proper 240VAC outlet and matching plug. That'll save you from accidentally feeding 240VAC to a device that only expects 120VAC.
 
6:42 AM
@JRE Ok Thank you. I am well aware of the typical split phase power. If I ended up doing the 240 V I would use a 20 amp 240-250 V locking outlet and locking male and female extension connectors.
@JRE The fuse box is a sub panel. The main fuse box is in the house. I have a sub box connected to the 240-250 V input from the house. So everything is technically on 1 system. But they are on seperate circuits.
@JRE The 240 Volts is needed to power 3 modified MOT's. The voltage will drop by 86. Once the 20 amp circuits are figured out, then I'll move to a 30 to use for my final connection. I need the higher voltage because the voltage drop will be too low to safely run anything.
The 86 volt drop is the minimal I have calculated, the worst is 103 volts. Either way if we did the math on a 123 volt RMS outlet, nothing would run safely or very well. Drills, machines and table saws would run very hot.
 
 
2 hours later…
JRE
9:01 AM
@ScientistSmithYT If you understood split phase as rather than just knowing about it, then this "question" would never occur to you.
 
9:19 AM
hi is anyone here in this chatroom..?
 
JRE
@user3696118 Nope. Nobody here but us chickens.
What's up?
 
Hi, i have a very specific electronics question, but i have no idea where to ask
would you be able to give me some resources of where to ask to? i have no knowledge of any of this stuff so i don't even really know how to ask
 
JRE
Tell me a little about your question. Maybe I can help you ask a good first question.
@user3696118
 
okay, well i suppose to put it very shortly, its kind of like "is it possible to create an accurate gps tracker utilizing these devices i already have?"
 
JRE
OK. That's really rather a broad question. As such, it'd get closed on the main site.
What devices do you have?
 
9:31 AM
like i have this cell phone, and two gps trackers i tried to use in the past and they had very poor accuracy
 
JRE
How poor? How do you know it was the fault of the devices?
 
and I just figured with smartphones, the reason why the location tracking on those are good because it utilizes both gps and cell tower info and thats why you can get sort of a 2 meter radius discrepency
i just thought "what if i took this cell phone and some how combined its components with these gps trackers"
oh that is an interesting question, well i suppose i dont really know. other than the fact that it just either kept jumping around an area
or it just loses signal completely, and they couldn't seem to utilize cell tower information very well, despite both of the trackers needs a sim card to send the data
i took photos of the two gps tracker's components if that helps. i haven't been able to open up the phone since its screws looks like a weird bit...
 
JRE
OK. There's no reason why a GPS tracker would use the cellphone data at all. GPS receivers are usually stand alone modules. The cellphone part usually just passes requests through to the GPS receiver and sends the data back to the asker - or just periodically ask the receiver for data and sends to be collected.
You'll not be electrically combining the trackers and your cell phone. Not that it is totally impossible, but this is one of those "if you have to ask how then you don't have the skills to do it" things.
 
huh... well i know at least for one of these trackers if the gps fails the site i used to track would usually say something like "Unable to locata via gps, retreiving location via GSM" or something like that
oh yeah i totally don't have the skills for it
 
JRE
I don't have the skills to do, though I have some idea what is involved.
 
9:38 AM
well having an idea is far better than my situation
 
JRE
OK. Then at least that tracker can use cellphone data.
 
yeah but the issue is it never worked
it would always give a location like 20meters away or something
 
JRE
Mmmpf. You do know that 20 meters is completely OK by GPS standards?
 
essentially, the end goal is me trying to figure out if i can create my own gps tracker that is small enough to fit somewhere inconspicuously on a bicycle
 
JRE
Do you need a tracker (know where the bike is in real time) or a logger (find out where the bike has been after the fact?)
 
9:41 AM
oh i understand for GPS it's fine, but then i asked myself "well then how come my iphone can track my location so much better?". and when i looked this up it was apparently a combination of gps and other data
oh... uhhh... i suppose real time is better...?
 
JRE
And, "inconspicuous" often translates as "under something," which is bad for GPS. The receiver antenna needs a clear line of sight to the sky. Nothing above it, and the antenna itself facing up.
 
but i think logging is okay too so long as i can just deliver that kind of info to authorities (or i try to confront the thief after the bike is stolen)
yes, my understanding of an idea envrionment of GPS trackers is that there is nothing around it
and that there are no clouds or something in the sky
so inside buildings and what not would totally ruin the accuracy of it
 
JRE
OK. You are trying to find out where it is when it has been stolen. Yeah, you need tracking rather than logging.
 
basically i am comparing the accuracy of location tracking to a smartphone
which means i have no idea how that works
 
JRE
Clouds aren't a problem (unless it's from a hurricane or monsoon.)
Your iPhone probably also uses wifi as well as cellphone data and GPS, and combines all three together with motion detection. So, you'll be looking for a very advanced (expensive) tracker that can do all of those things.
 
9:45 AM
ohh i see, wifi is also a key element
but then say like
 
JRE
Inside of buildings doesn't just ruin the accuracy of GPS, it can block it entirely.
 
i had an old smartphone lying around
could i some how take some of its components and make a tracker that has all GPS, cellphone, and wifi capabilities?
 
JRE
There are programs that you can install on a smartphone to make them into trackers. You won't be combining components from a smartphone to do all of that. The combining is done in software.
 
i thought about just using a smartphone just as a tracker
but they're too big for me to "hide" them in a bike
i feel like what i am describing is essentally movie magic nonsense
 
JRE
I can promise you that nothing you build at home will be as small as a smartphone.
 
9:49 AM
oh i see
even if you say bought components that has each of those capabilites?
 
JRE
What you are describing is possible, just not as a DIY project.
 
like what if i used say a rasberry pi with a bunch of other components
how "big" do you think that would be dimensionally?
 
JRE
The final "component" is a microprocessor that combines all the information into a location.
 
is that not actually small?
or stupid expensive?
 
JRE
Anything you can build at home will have to be larger. The inside of smartphone is pretty nearly full - no empty space. Anything you build at home will not be optimized for small size. It'll be optimized for having to build it by hand with human sized tools.
 
9:53 AM
ohh i see, compared to smartphones where they are manufactured via robotic machines and what not
 
JRE
The processor can be small. The battery won't be small. It takes up most of the volume of your smartphone.
 
right, battery
okay then spinning the idea, would it be more of a plausible idea if i could find a really small smartphone
and somehow set that small smartphone up to just be used as a tracker?
and maybe i can just duct tape the sucker on a bike
 
JRE
A small smartphone is probably your best bet. Along with a program that sends the location data to someplace you can receive it.
That'd be a fun project, but it is software rather than hardware.
 
because after that point its more of a "software" issue right?
because the hardware would arleady be packed into the device?
 
JRE
Duct tape the tracker to the bike, then hope the thief doesn't sell the phone separately from the bike. :)
 
9:59 AM
oh yeah haha, that's an entirely separate issue
 
JRE
Yep. Pretty much any smartphone will have the sensors you need. Then you need a database of wifi hotspots, and access to the celltower data. GPS of course. Motion detection. A Kallmann filter in software to fuse all the different inputs to final location value.
 
hmmmmmm
 
JRE
I think the location services on Android phones does all of that already. You ask the phone for the location rather than reading the GPS data directly.
 
i'm assuming android based phones would probably be best for this type of stuff
yeah that does sound like a more realistic approach
okay, then i thinhk i am gonna take my searches in that direction
wow thank you so much though for clarifying so many things
 
JRE
The development software for Android is freely available. Apple may be available for free as well. I don't know. Android does have a larger developer pool (more people working with it,) though, so you'll find more help on the internet for Android.
 
10:04 AM
well i think nowadays developing for androids are far less strict than for apple ios
 
JRE
Probably.
 
before the ios jailbroken community used to be way bigger before Apple went all rage mode
 
JRE
I don't think you'd need to jail break an iPhone. Everything you need to do should be workable from the normal development tools.
Shouldn't need to jailbreak an Android, either. Just the official tools should do. They are free to use.
 
oh you mean to create an app or something that does what you described?
something that just queries the current location and sending it some place?
hmm then again when i go searching there may already be methods on how to do this on an android
so it might actually be much more simple...
 
JRE
Yes. Just an app that runs as a background service, and constantly sends its location to you or some server that you operate. You could make it constantly send its location, or send its location on request.
There might well be an app available that does just what you need.
 
10:10 AM
wow,
then i suppose the main thing is the device itself
seems like there are a few small smartphone in the market anyways
okay then i am difintely going to look more into this
thank you so much again for your help in clarifying all of this!!
 
JRE
Ok. Good luck.
 
genius, scholar!
 
JRE
Oh! You might find an older phone. My old android phone (5 or 6 yeats ago) was much smaller than the current phones.
 
right so maybe that might be a good idea too
thank you again! full of great ideas!
 
JRE
OK. Gotta go. Lunch time in this neck of the woods.
 
10:14 AM
for sure, have a great one sir!
 
 
6 hours later…
3:57 PM
Bluetooth Key Finders, such as Tile or this $20 one would be a lot easier, functionally:
https://www.amazon.com/Bluetooth-Finder-Keychain-Tracker-Keys/dp/B01CMJ6GNG
Most bike locks will do fine. If you want higher end, use a U-lock. If you want the best of the best, use Forever Lock. (One video of a guy seems to have picked it, but his work hasn't been replicated. I think he tried some wonky impressioning technique, but no one will go that far to pick a lock anyway.)
...JRE in Europe?...
 
JRE
@adamaero Germany.
 
:)
@rdtsc Where are you from?
 
4:15 PM
@JRE Sorry, but I do understand the behaviour of split phase electricity. I should have made that more clear. And that's no excuse to not have this type of question.
 
JRE
@ScientistSmithYT If you understand split phase, then the answer is obvious. If you have to ask the question, then you don't understand as well as you think you do.
 
@JRE Well the answer was obvious until I thought about other possibilities as to where it might not work very well. I also thought I made that very clear. That's why I questioned it in the first place.
 
@adamaero US... although rather ashamed anymore to say so. You?
 
@JRE I don't just jump on something right away just because I found a way something works without second guessing it. That is stupid and is asking for trouble. A lot of people do that these days and it isn't a good habit.
@JRE Since we can't do a waveform analysis. And I have other people I can talk to about this. I'll call it quits for now.
 
4:53 PM
@rdtsc Wisconso
 
JRE
5:11 PM
@ScientistSmithYT Buy two of these. That's a 120VAC to 24VAC center tapped transformer.
Connect bannana jacks to the three output wires. Attach a 120VAC plug and cable to the primary. Put each transformer in its own insulated box with the banana jacks outside.
You now have two models of a split phase residential system that you can play with without killing yourself. First task: understand why it accurately represents a residential split phase system
Second task: Arrange the secondaries so that you get 48 VAC.
Third task: Unplug one transformer from the outlet, and flip it 180 degtees and plug it back in. What happened to your 48VAC?
Get out your oscilloscope. Observe the voltages. Use a two channel scope, and observe the two hots on one transformer. Observe the hot versus the neutral on one transformer. Obseve the neutrals from both against each other.
That should teach you a lot of stuff you need to understand before you start cross connecting outlets.
You ought to be scared spitless when you consider intentionally connecting something to your outlets, and you expect it to cause the line voltage to dropby 86 volts.
@ScientistSmithYT You don't need a "waveform analysis." You need a "wait, WTF?" moment before you start doing this stuff.
And, I have no idea where you get the concept of a "skip" when you hook two outlets in series.
Haven't we been through this before? I seem to remember you claiming to have successfully connected two outlets in series and not understanding why everyone says not to do something you did "so easily."
 
5:33 PM
We had a band practice in a basement years ago. Someone ran a power cord from the other side of the basement to the mixer. When a patch cord was connected between the mixer and my amp.... BZZZZT! Destroyed the amp. It is still sitting in pieces (replacing class A/B amp with class D, a project I'll never have enough time to finish.)
 
JRE
@rdtsc 😁
And somebody is wondering what your story has to do with why you shouldn't connect outlets in series.
 
 
3 hours later…
9:03 PM
@JRE Well I got a waveform analysis from my friend and it turns out that the sine waves are not matching up perfectly. And at one point they skip a cycle. So it won't work. And seriously all of that work just to not prove a point??? ... Hmmm. And actually no, I did need a waveform analysis. Because it gave me the answers to the questions I have way faster than what you have described.
@JRE I'm not scared spitless. But maybe people that arent experienced would be scared spitless.
@JRE And I am well aware of how split phase works. It come to no suprise to me. It all goes down to the smallest of basics.
 
 
1 hour later…
10:12 PM
Hi everyone.
Guys what's the disadvantages of building a lab PSU based on LM338? 0-24V/3A digitally controlled...
 
10:33 PM
@newbie the big problems with linear lab supplies are twofold: 1) getting that Vin 2) cooling your regulator
 
Somehow, this became a hot network question...
5
Q: Please help me to read schematic

VectorI am doing repairs on a monitor of mine and I have to replace a thermistor. I cannot quite read the values of the thermistor on the schematic for the monitor. Can someone see the image and help me to understand this?

 
11:19 PM
@newbie That schematic does not show a digitally controlled voltage output. Did you notice that it needs +25V and -10V inputs?
 

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