|
The 555 is a long-obsolete convenience part but if you're wondering what it evolved into check out the datasheets for the timerblox series. Bet you could flash an LED with one of those too.
|
#
?
May 18, 2021 14:49
|
|
|
|
| # ? May 28, 2024 10:38 |
|
|
Stack Machine posted:The 555 is a long-obsolete convenience part but if you're wondering what it evolved into check out the datasheets for the timerblox series. Oh, I used one of those to convert an analog signal into a PWM signal to get it across an isolator once, worked great. Also I once swapped out a 555 for a 7555 without thinking too hard about it and suddenly found the circuit was running at like a few megahertz instead of the tens of kilohertz it was supposed to 
|
|
#
?
May 18, 2021 15:28
|
|
|
Forseti posted:Everyone has days where we don't feel ourselves friend, if you want to take a nap or something, well, there's never a bad time for a nap. But if you think you've wronged the thread or something like that, I don't think that's true and I don't think there's any reason for you to feel obligated to duck out. Especially having voiced the context Yeah, thanks much, it's good to hear. I'm sorry to see this thread is so far beyond my skill set and knowledge because I don't want to just be a part of "maker culture" but there are no active relevant threads at SA. The DIY instrument thread is deader than a doornail. I'll probably come begging for help again sometime soon.
|
|
#
?
May 18, 2021 15:54
|
|
|
Quick question that I'm having a hard time searching: I have a system that's charging LiFePO4 batteries with 54V @ 25A using spring contacts. If contact is broken unexpectedly, my intuition is that intermittent or poor contact during the transition (i.e. bouncing or nontrivial impedance) is bad news that could cause arcing or otherwise deteriorate the system. Nothing catastrophic, but possibly lifetime shortening. Am I being overly paranoid? Do I need to find a way to add intelligence or a safety interlock to break the contact more gracefully upstream?
|
|
#
?
May 18, 2021 18:03
|
|
|
KnifeWrench posted:Quick question that I'm having a hard time searching: I have a system that's charging LiFePO4 batteries with 54V @ 25A using spring contacts. If contact is broken unexpectedly, my intuition is that intermittent or poor contact during the transition (i.e. bouncing or nontrivial impedance) is bad news that could cause arcing or otherwise deteriorate the system. Nothing catastrophic, but possibly lifetime shortening. That'll definitely strike a nasty arc if it disconnects suddenly, you've basically got a small-mid-size DC arc welder going there. Battery contacts aren't really rated to break that kind of current afaik, so if you think it's a real possibility that someone would yank the battery out some kinda interlock is probably a good idea, yeah. Maybe just a door with a microswitch?
|
|
#
?
May 18, 2021 18:07
|
|
|
petit choux posted:Yeah, thanks much, it's good to hear. I'm sorry to see this thread is so far beyond my skill set and knowledge because I don't want to just be a part of "maker culture" but there are no active relevant threads at SA. The DIY instrument thread is deader than a doornail. I'll probably come begging for help again sometime soon. I didn't even know there was a DIY instrument thread. Could you link please, I like instruments.
|
|
#
?
May 18, 2021 18:37
|
|
|
Shame Boy posted:That'll definitely strike a nasty arc if it disconnects suddenly, you've basically got a small-mid-size DC arc welder going there. Battery contacts aren't really rated to break that kind of current afaik, so if you think it's a real possibility that someone would yank the battery out some kinda interlock is probably a good idea, yeah. Maybe just a door with a microswitch? It's not connecting directly to battery terminals, but rather charging plates for a robot dock. But point taken; my instincts aren't miscalibrated and I should continue heeding them -- I'm not wasting time over-engineering.
|
|
#
?
May 18, 2021 18:45
|
|
|
KnifeWrench posted:Quick question that I'm having a hard time searching: I have a system that's charging LiFePO4 batteries with 54V @ 25A using spring contacts. If contact is broken unexpectedly, my intuition is that intermittent or poor contact during the transition (i.e. bouncing or nontrivial impedance) is bad news that could cause arcing or otherwise deteriorate the system. Nothing catastrophic, but possibly lifetime shortening. Yeah for a battery pack like that, standard design practice would be to include a fuse + accumulator isolation relay (AIR) that cuts power through the spring contacts before any motion could potentially break the connection. You don't want to be accidentally breaking and making that sort of contact under those loads. Hopefully there is a pretty strong lever arm clamping the pack to the charger? e; AIR is just a use case term, not a type of relay. Its just a large relay used to interrupt flow to and from any major power accumulator such as a battery or capacitor.
|
|
#
?
May 18, 2021 18:52
|
|
|
petit choux posted:Yeah, thanks much, it's good to hear. I'm sorry to see this thread is so far beyond my skill set and knowledge because I don't want to just be a part of "maker culture" but there are no active relevant threads at SA. The DIY instrument thread is deader than a doornail. I'll probably come begging for help again sometime soon. If you're feeling inadequate that's a good sign that you're learning something. I don't think there's any way around it if you're trying to make something new and cool. You gotta own it. Nobody can stop you from posting. Watch this Power is directly proportional to current. Pi is exactly 3.  e. vvv uh ok, yeah. I should add that maybe starting with a power circuit project isn't the best idea. You can't bungle your way through safety precautions. Other than that go hog wild ee. OH YEAH I FORgot about LASERS. Maybe lasers is a bad idea. Or... maybe lasers is a good idea? 
Cory Parsnipson fucked around with this message at 21:23 on May 18, 2021 |
|
#
?
May 18, 2021 21:15
|
|
|
It's the amperage that kills you, not the voltage
|
|
#
?
May 18, 2021 21:17
|
|
|
KnifeWrench posted:It's not connecting directly to battery terminals, but rather charging plates for a robot dock. But point taken; my instincts aren't miscalibrated and I should continue heeding them -- I'm not wasting time over-engineering. I was more thinking about the springs, which are going to turn into whimsical spiral welding rods at the first opportunity, but yeah you're on the right track
|
|
#
?
May 18, 2021 22:27
|
|
|
I’m so new I just want to kits and projects to get soldering practice. I understand what the components are and what they do, but the math is beyond me for now. I just like putting poo poo together.
|
|
#
?
May 18, 2021 23:00
|
|
|
ante posted:It's the amperage that kills you, not the voltage i hate this statement!! you cannot have current without voltage!! go grab the terminals of a 12v car battery, capable of sourcing hundreds of amperes, and see what happens!! i also hate the malformed and improper term "amperage"!!
|
|
#
?
May 18, 2021 23:10
|
|
|
Can you also explain how current actually goes the other way?
|
|
#
?
May 18, 2021 23:13
|
|
|
Current is the flow of electrons and electrons have a negative charge, so they come out of the negative part of the battery.
|
|
#
?
May 18, 2021 23:23
|
|
|
e: nevermind misread something
|
|
#
?
May 18, 2021 23:33
|
|
|
Cojawfee posted:Can you also explain how current actually goes the other way? I posted about this in the physics thread a while ago but I love this bit: Wikipedia article on Anode posted:The word was coined in 1834 from the Greek ἄνοδος (anodos), 'ascent', by William Whewell, who had been consulted[3] by Michael Faraday over some new names needed to complete a paper on the recently discovered process of electrolysis. In that paper Faraday explained that when an electrolytic cell is oriented so that electric current traverses the "decomposing body" (electrolyte) in a direction "from East to West, or, which will strengthen this help to the memory, that in which the sun appears to move", the anode is where the current enters the electrolyte, on the East side: "ano upwards, odos a way; the way which the sun rises".[4][5] Even long before the electron was discovered, Faraday was trying to get out ahead of the possibility that conventional current was different from an actual matter "flow" by defining it in relationship to the earth's magnetic field. Also I like "Eastode" and "Westode" for how far a goddamn walk they are.
|
|
#
?
May 18, 2021 23:39
|
|
|
Sagebrush posted:i also hate the malformed and improper term "amperage"!! I never use "amperage" and don't know anybody who does (e: well, "know" in the very narrow sense of "work closely with") but it's amusing nobody seems to feel that way about the more-or-less universal use of the word "voltage" instead of "potential" outside of elementary physics texts. Like I've never heard anybody talk about a "potential source" or "potential divider". Stack Machine fucked around with this message at 00:28 on May 19, 2021 |
|
#
?
May 19, 2021 00:19
|
|
|
Cojawfee posted:Can you also explain how current actually goes the other way?
|
|
#
?
May 19, 2021 00:37
|
|
|
Electricity always flows in the path of least resistance. Example: If you have three parallel resistors of different value 100% of the current will flow through the resistor with the lowest value.
|
|
#
?
May 19, 2021 00:54
|
|
|
Stack Machine posted:I never use "amperage" and don't know anybody who does (e: well, "know" in the very narrow sense of "work closely with") but it's amusing nobody seems to feel that way about the more-or-less universal use of the word "voltage" instead of "potential" outside of elementary physics texts. Like I've never heard anybody talk about a "potential source" or "potential divider". Probably because of the other meanings of the word "potential" causing confusion. And yes, this exact thing happens with "current" as well, leading me to develop a persnickety habit of referring to contemporary components as the "present" supply/sensor/connector/etc. to avoid ambiguity.
|
|
#
?
May 19, 2021 00:55
|
|
|
Electrical energy flows through conductors In something like a coax cable at RF, all the energy is carried by fields in the dielectric, not the copper
|
|
#
?
May 19, 2021 00:57
|
|
|
PDP-1 posted:Electricity always flows in the path of least resistance. Then why doesn’t electricity answer my 1am “you up?” texts?
|
|
#
?
May 19, 2021 01:39
|
|
|
Stack Machine posted:I never use "amperage" and don't know anybody who does (e: well, "know" in the very narrow sense of "work closely with") but it's amusing nobody seems to feel that way about the more-or-less universal use of the word "voltage" instead of "potential" outside of elementary physics texts. Like I've never heard anybody talk about a "potential source" or "potential divider". I've heard "potential divider" a bunch, not potential source though. Also "tension", which confused the hell out of me for a while cuz like, why would I need to know about the mechanical strain on the wire instead of how much electricity is in it???
|
|
#
?
May 19, 2021 02:06
|
|
|
Shame Boy posted:I've heard "potential divider" a bunch, not potential source though. If you see a potential source you are probably discussing EM field theory or numerical methods. Tension is something I have only seen in mistranslations from German.
|
|
#
?
May 19, 2021 11:15
|
|
|
I've heard it referring to power transmission lines, electric fences, and old car ignition parts.
|
|
#
?
May 19, 2021 12:19
|
|
|
Pro tip: If your PCB has an unstable power rail, you can just add a few more condensers here and there
|
|
#
?
May 19, 2021 16:03
|
|
|
ante posted:Pro tip: It's funny how using old timey terms can make you sound like an extra on a SyFy original.
|
|
#
?
May 19, 2021 16:16
|
|
|
ante posted:Pro tip: wtf is a PCB 
|
|
#
?
May 19, 2021 17:04
|
|
|
Forseti posted:wtf is a PCB It's what kids these days call a PWB
|
|
#
?
May 19, 2021 17:19
|
|
|
Forseti posted:wtf is a PCB Polychlorinated biphenyl, a persistent environmental pollutant and carcinogen e: Wikipedia also says it's one of the Touhou games, I wanna change my answer to that
|
|
#
?
May 19, 2021 17:38
|
|
|
Foxfire_ posted:Electrical energy flows through conductors It’s the same for DC and power frequencies, there’s never (much) energy in conductors. Or magnetic circuits for that matter.
|
|
#
?
May 19, 2021 18:32
|
|
|
Forseti posted:wtf is a PCB Printed Circuit Board. Everybody seems to forget the title of the thread is “Learning Electronics”.
|
|
#
?
May 19, 2021 18:44
|
|
|
Marsupial Ape posted:Printed Circuit Board. Just making a bad joke because widespread use of PCBs is a good bit more recent than the terminology shift from condenser to capacitor (I think).  Although I have this nagging feeling I'm getting wooshed here...
|
|
#
?
May 19, 2021 19:13
|
|
|
Marsupial Ape posted:I’m so new I just want to kits and projects to get soldering practice. I understand what the components are and what they do, but the math is beyond me for now. I just like putting poo poo together. I have a couple kits. Maybe I can fine one or two I can spare if you like. The question I came here with is: hey guys I just scavenged a streetlamp. I think it's mercury vapor, something like it. Is there anything of use inside it? Probably a giant cap, right? Maybe a huge transformer? (I'll open 'er up tomorrow) But also, I'm going to crosspost from the diy instruments thread, seeking any additional advice (which should also answer questions of where it is): petit choux posted:I found this cool gadget at the thrift, it's apparently a game: petit choux fucked around with this message at 04:48 on May 20, 2021 |
|
#
?
May 20, 2021 04:39
|
|
|
petit choux posted:I have a couple kits. Maybe I can fine one or two I can spare if you like. I have no idea, only conjecture, but I wouldn't think there'd be much of anything in the bulb assembly if that's the part you've got. I'd expect any expensive bits to be in the lamp post part itself to reduce maintenance costs. Definitely be interested in seeing what's inside if you open it though! If there's a transformer, it's probably disappointingly small and run at high frequencies to reduce material costs I bet (like what's inside of a CFL bulb). I have an oddball question because I was just reading planar transmission lines, but what happens if you run an electrical circuit at higher than microwave frequencies? Has this just never been done? Infrared starts at 300GHz which is already way high, I'm guessing parasitic inductance/capacitance may make this impossible to date? Or is, say, an incandescent light bulb already operating at visible light frequencies on some level, proven simply because we are able to see it?  Edit: Actually I guess the "on some level" bit is a bit too open because obviously it is if it's producing light at those frequencies. Guess I'm just curious if it's an electrical thing as opposed to "the atoms are just hot and wiggling around at those frequencies". Or maybe the distinction is pointless and the fundamental physical processes are the same, we just call them differently at such far apart spots on the spectrum Forseti fucked around with this message at 18:52 on May 20, 2021 |
|
#
?
May 20, 2021 18:40
|
|
|
Forseti posted:I have no idea, only conjecture, but I wouldn't think there'd be much of anything in the bulb assembly if that's the part you've got. I'd expect any expensive bits to be in the lamp post part itself to reduce maintenance costs. Definitely be interested in seeing what's inside if you open it though! If there's a transformer, it's probably disappointingly small and run at high frequencies to reduce material costs I bet (like what's inside of a CFL bulb). I love oddball questions like this. And yeah, I have the lamp post part too. It's heavy as hell and I think it's a safe bet that it's a transformer making up most of that weight. But now I've spent half my day with Netgear's "customer support" who are apparently Russians telling me I have to install firewall software that they conveniently can install for me right now and I won't be able to use the router with out it. gently caress!! The official installer app sent me to them, too. Maybe I downloaded a hacked app. Anyway, I'll probably just leave it in the truck for right now, now that half my day has been blown.
|
|
#
?
May 20, 2021 18:57
|
|
|
I guess one issue you'd run into is that 300 GHz is a wavelength of about 1 mm so I guess when you start getting to these frequencies it's hard to keep the width of say a transmission line smaller than the wavelength to avoid reflections and such from happening in all directions or whatever Edit: Although I guess you could end up with something more like a fiber optic cable if you could design something to take advantage of total internal reflection? Now I'm back to being suspicious that a fiber optic cable is what you'd end up with and we just don't use the same terminology when talking about it Forseti fucked around with this message at 19:57 on May 20, 2021 |
|
#
?
May 20, 2021 19:41
|
|
|
I used to know some people who worked with THz devices. It was mostly upscaled optical gear and not downscaled microwave gear.
|
|
#
?
May 20, 2021 20:01
|
|
|
|
| # ? May 28, 2024 10:38 |
|
|
I got one of these nice-rear end enclosures: https://chevalstore.com/product/sacn4-0d2w3-aluminum-enclosure-4u-175x279x432-mm/ Really cool looking and high quality, definitely check out Cheval if anyone needs a nice metal box to put stuff in. Anyway, the box is built out of separate panels that are each powder coated all over. Their solution for grounding was to include a slip of paper saying that they can't predict what your grounding needs are so they didn't do anything at all and it's up to you to make the best decisions. What do I do to get it all grounded? I can't really solder to it, it's aluminum, so I'm guessing my options are down to just "drill a hole in each of the 6 sides, scrape off some of the paint and use ring terminals and star washers to connect 6 separate wires back to a central ground point" which seems kinda messy and a bit of a pain in the rear end. Anyone have a better idea?
|
|
#
?
May 20, 2021 20:22
|
|