|
Splode posted:I'm not sure I am following, are you using relays that have a 120V input voltage? The only way to switch that is going to be another relay. Yes, the current relays have 120VAC coils, with 240VAC on their contacts. Doing some research, I may just need an "optocoupler." It seems like those will switch 120VAC, protect the logic-level stuff, and some have zero-crossing circuits built in for less noisy switching, which is probably a bonus that nobody knows about since the current relays are probably god-awful noisy (electrically). The datasheet for the MOC3023 makes the optotriac control another triac to control the load. If my load (a relay, in this case) pulls less than 100mA continuous, can I use just the MOC3023 alone and have a (very tiny) SSR?
|
#
?
Jul 30, 2017 01:57
|
|
|
|
| # ? Jun 9, 2024 23:19 |
|
|
These are common, cheap, and probably won't burn your house down. http://www.ebay.com/itm/5v-Eight-8-...WQAAOSwFnFV9O0w And if you don't want clicking, and are ok with just a little more expensive. http://www.ebay.com/itm/W6-5v-8-Cha...lQAAOSwo4pYIGfN
|
|
#
?
Jul 30, 2017 03:24
|
|
|
I found a dev kit with a psoc4 for 4 earth dollars and psoc5 for  I sthis worth buyingHow do they compare to the teensy
|
|
#
?
Jul 30, 2017 03:54
|
|
|
Malcolm XML posted:I found a dev kit with a psoc4 for 4 earth dollars and psoc5 for ~3 years ago I bought a bunch of the 4s. The IDE crashed while loading the blink project, and I never touched it again. They don't compare at all - Apples and oranges. The Teensy is a speedy Arduino-compatible and well support platform, while the PSoC is a (more normal) jankily supported micro with some totally rad reconfigurable logic. Unless you know you need the logic, or are a beginner in the world of embedded, you want the Teensy. Combat Pretzel posted:About reflowing, poo poo's too crowded on the board I'm trying to route, but I have plenty of caps top-side that are annoying. Is the surface tension of solder high enough to keep 0603 parts from falling off a bottom side after they've been soldered? Yep, easily. Surface tension even works with most large SMD chips, too.
|
|
#
?
Jul 30, 2017 05:12
|
|
|
Aurium posted:These are common, cheap, and probably won't burn your house down. These are awesome and you are awesome.
|
|
#
?
Jul 30, 2017 15:45
|
|
|
I've heard people who said that the cheap China blue mechanical relays are rated for 10 amps but aren't really safe for continuous use at that level. They heat up pretty hot. If that is a limitation of the relays themselves or the PCB traces I don't know. I've used the cheap China relay boards for controlling ~4 amps @ 120VAC in a 30-seconds cycle that sometimes goes 3 or 4 cycles in a row 'on', and not had a heating problem. About that solid-state thing,,, normal solid-state relays have a much lower current limit (usually 2 amps) and are only for controlling AC power. The reason that they can control AC power only is because they are (usually) triacs which switches off on the zero-volt crossing of an AC sine wave. If you use them to switch DC they will turn on, but won't turn off. You can buy big-power solid-state relays to control AC power on Amazon for ~$10 each. Many are ~300 volts and rated for 30-40-50 amps. You can buy big-power solid-state relays that are safe to use with DC power output, but you have to shop for them particularly. Try searching Google for "forklift motor relay". $40 ~ $100+ each is typical, depending on the volts/amps you want.
|
|
#
?
Jul 30, 2017 18:30
|
|
|
LMAO don't cheap out on relays for mains that poo poo can and will burn your house down Also your insurance won't cover it and may be invalidated if you didn't get ul certified
|
|
#
?
Jul 30, 2017 19:37
|
|
|
edmund745 posted:I've heard people who said that the cheap China blue mechanical relays are rated for 10 amps but aren't really safe for continuous use at that level. They heat up pretty hot. I just have to control the relays that are controlling the high-power stuff. <150mA max on the big six-pole guy. Also AC, so I don't particularly care about the DC voltage rating. The things actually controlling the mains-level stuff are UL listed definite-purpose contactors of appropriate rating. The motor ones are even horsepower-rated, and are over-specced.
|
|
#
?
Jul 30, 2017 19:59
|
|
|
Doesn't matter if your components are UL, his point was the whole device must be UL-approved. It won't be a problem if there is never a problem. But if there is a problem, your insurance will gently caress you with it if they find out.
|
|
#
?
Jul 30, 2017 20:44
|
|
|
Best not build anything ever then, because what you're building won't be approved, unless you send the whole assembly to UL.
|
|
#
?
Jul 30, 2017 23:58
|
|
|
Aurium posted:Best not build anything ever then, because what you're building won't be approved, unless you send the whole assembly to UL. Most things you build don't operate on mains voltage and therefore don't fall under the same regulatory categories (or at the very least are much less likely to burn your house down)
|
|
#
?
Jul 31, 2017 00:01
|
|
|
Yes, in fact, it's pretty good advice to say "don't build anything that switches main wall power and runs unattended." Or if you do, put it in your shed on a concrete pad, and not in the house.
|
|
#
?
Jul 31, 2017 00:02
|
|
|
ate all the Oreos posted:Most things you build don't operate on mains voltage and therefore don't fall under the same regulatory categories (or at the very least are much less likely to burn your house down) Eh, power is power, and considering how cheap high power dc supplies are these days it's pretty easy to burn your house down with 12v too. The recent rash of 3d printer issues were caused by 12v, poor connectors and poor pads.
|
|
#
?
Jul 31, 2017 00:12
|
|
|
Aurium posted:Best not build anything ever then, because what you're building won't be approved, unless you send the whole assembly to UL. No, it means just be aware that your HOI won't cover your rear end when your hardwired hobby project burns down your house. The frequency of house fires has plummeted in most countries, due to two things. 1: electrical codes for the in wall wiring 2: UL certs (or the euro/asia equivalent) for consumer products. Put appropriately sized fuses or circuit breakers on your project, and you will be fine. Just be aware of the risks, electricity is dangerous.
|
|
#
?
Jul 31, 2017 01:16
|
|
|
Aurium posted:Eh, power is power, and considering how cheap high power dc supplies are these days it's pretty easy to burn your house down with 12v too. I was going to say that 3D printers aren't meant to run 24/7 unattended but actually that's how most people use them so 
|
|
#
?
Jul 31, 2017 01:48
|
|
|
ate all the Oreos posted:I was going to say that 3D printers aren't meant to run 24/7 unattended but actually that's how most people use them so Yeah nobody is going to sit there watching their printer work for 3 days. -- I've ordered a beefier relay from a more reputable manufacturer to hopefully swap with the one in my module. I'm hoping it doesn't produce as much heat when operating for long periods (but I'm not holding my breath). Why can't all household appliances have an accessible serial port and open source command set, geez.
|
|
#
?
Jul 31, 2017 02:49
|
|
|
MRC48B posted:No, it means just be aware that your HOI won't cover your rear end when your hardwired hobby project burns down your house. There is one way to switch mains stuff with homespun nonsense safely... 
|
|
#
?
Jul 31, 2017 03:13
|
|
|
Stabby McDamage posted:There is one way to switch mains stuff with homespun nonsense safely... That doesn't look like it's properly grounded at all, you could have five volts running straight through you!
|
|
#
?
Jul 31, 2017 05:15
|
|
|
ante posted:~3 years ago I bought a bunch of the 4s. The IDE crashed while loading the blink project, and I never touched it again. i am indeed an embedded beginner and i dont need the raw speed so much, i could hook up an rpi to do crunching and then async send it to the micro other stuff im lookin at is esp32 but for $4 you dont get much
|
|
#
?
Aug 1, 2017 02:36
|
|
|
I've got some sound gear to repair (replace pots, rebuild cables, that kind of thing), and I'm a little out of practice with my soldering experience. Last time I did any major soldering work was over 15 years ago in a high school electronics class. My cheapo radioshack iron got lost in a move some time ago. What's the thread's current recommendation on all-in-one soldering stations? I'll mostly be tinning and replacing parts on circuit boards, but I may have to work up to some surface mount repairs. I don't plan to do any electronics builds, only repairs. I've seen the thread talk about the Hakko FX-888, which looks like it'd work and I'm willing to make the investment, but I'd like to know if there are any other options out there. I could also use some instructional videos/resources, since all I can remember is heatsink ICs, pointy end is hot, and heat part and apply solder. I know I can google them, but hearing the thread's opinion on good/poo poo would help me sort through the thousands of lovely how-to videos and pages. Any help would be appreciated.
|
|
#
?
Aug 1, 2017 17:37
|
|
|
Brute Squad posted:I've got some sound gear to repair (replace pots, rebuild cables, that kind of thing), and I'm a little out of practice with my soldering experience. Last time I did any major soldering work was over 15 years ago in a high school electronics class. My cheapo radioshack iron got lost in a move some time ago. That's a good iron and probably what everyone else is going to suggest too. If you're possibly dealing with surface mount stuff, I suggest getting a fine point tip for it too. If you're working on pro level sound gear, I have found that the smaller tip is more useful for soldering XLR connectors. You'll also want to pick up a flux pen, a small thing of tip tinner, and a wire tip cleaner (don't use the wet sponge that comes with most iron holders). Don't piss around with lead-free solder, get the good stuff and for most repair work the smaller diameter is going to be your best bet to control the amount you're putting down. You'll also want to pick up some solder wick to remove excess solder/desolder existing joints. Don't bother with the spring-loaded pumps, and if you're going to be doing a lot of desoldering you should get a dedicated desoldering iron to make your life easier. As for videos that cover technique, I think the best one I've seen is the EEVblog series on it: https://www.youtube.com/watch?v=J5Sb21qbpEQ
|
|
#
?
Aug 1, 2017 18:38
|
|
|
Brute Squad posted:I've got some sound gear to repair (replace pots, rebuild cables, that kind of thing), and I'm a little out of practice with my soldering experience. Last time I did any major soldering work was over 15 years ago in a high school electronics class. My cheapo radioshack iron got lost in a move some time ago. Get a temp controled iron. They're cheap enough these days that there's no excuse for not getting one. The good about the 888: The build quality and and quality control are good. Cheap irons will be be inconsistent with both. It's 90w so it heats up fast and has good temp control even under heavy load. Typical cheap irons will be about half the wattage. It lets them use a smaller transformer. There's some other, more minor things, like static dissipative plastic that are less important. The bad: It's about 2x as expensive as good cheap irons. The aoyue stuff, which is probably the most common of the cloners, is typically fine. The original design is pretty robust so even the cheapest of the cloners typically work acceptably. Look at the eevblog $20 iron teardown for example. Combined machines work well enough, but I bought an 888, and a cheap separate hot air rework, because I almost never use hot air. I like the 858 style of hot air because it's a lot quieter, and has a much more flexible cord over the 957 style. The 858 has a fan in the hand piece, where the 957 type has an air pump on the station. Most of the combined stations use the 957 style, so that's a mark against them, IMO. On the other hand my super cheap hot air station arrived broken, and I had to fix it. Another cheap iron the look at is the ts100, though it needs a separate power brick, uses a smaller than typical connector, and isn't that cheap, but works very well. Pace has a really good set of tutorials on YouTube. Some of the techniques are obsolete, as the parts they're done on aren't used anymore, but it's pretty great. https://m.youtube.com/playlist?list=PL926EC0F1F93C1837
|
|
#
?
Aug 1, 2017 19:06
|
|
|
Looks like this video was made specifically for your post https://www.youtube.com/watch?v=aIab66EgfHM
|
|
#
?
Aug 1, 2017 19:08
|
|
|
Guys I want to consider buying a reflow oven for our lab so we can properly replace large surface mount fets on existing boards. Suggestions? Also extech vs fluke? Opinions there? We have a couple extechs that I think are fine but they almost universally have mediocre Amazon reviews citing quality problems.
|
|
#
?
Aug 4, 2017 14:18
|
|
|
Fluke. Extech stuff is largely cheap and has varying issues based on model. Fluke is... well, Fluke. Industry standard for a reason.
|
|
#
?
Aug 4, 2017 14:40
|
|
|
I got a mid-range Extech meter as my first one and... yeah go with Fluke. It feels physically cheap, like it's made out of that crappy plastic, and taking it apart once just to change a fuse managed to somehow break the contact test beeper so it doesn't beep anymore. Also didn't seem to have very good blast protection so I wouldn't trust it not to blow your hand apart if you actually tried to use it in Cat IV situations
|
|
#
?
Aug 4, 2017 14:59
|
|
|
Uhg. Extech is like half the price which I'd translate into buying twice as many. Sometime setups benefit from 2, 3 or 4 dmms at a time. I'll think about it.
|
|
#
?
Aug 4, 2017 16:55
|
|
|
Our one and only Extech meter took a tumble off the top of an airplane a couple of months ago and shattered into about a trillion pieces. Nothing of value was lost.
|
|
#
?
Aug 4, 2017 17:06
|
|
|
asdf32 posted:Uhg. Extech is like half the price which I'd translate into buying twice as many. Sometime setups benefit from 2, 3 or 4 dmms at a time. I'll think about it. Depends on what you need it for I guess, if you just need to monitor low power stuff from 3 or 4 different test points, I got this one recently for that reason: https://www.amazon.com/gp/product/B071H8PR61 Nice big screen, you can push the buttons without it falling over on the tilting bale, seems accurate and responsive. I wouldn't trust it not to blow your hand up still but it's definitely better than the extech I have (that cost about the same amount) My main meter is still a not-poo poo one though
|
|
#
?
Aug 4, 2017 17:40
|
|
|
Fluke makes DMMs intended for domestic use only in China that are much more affordable/great bang for your buck. They're not knockoffs (teardowns are on Youtube), and you can buy them off Aliexpress (and maybe eBay?).
|
|
#
?
Aug 4, 2017 18:58
|
|
|
The China meters work just fine IMO, but if you're spending other people's money then go for gold. The main advantage of a higher-end meter is that they won't be damaged (beyond the fuse) if someone uses them wrong. You get that a lot in lab situations, where the people trying to use the meter don't have to pay to replace it. The accuracy of cheap China meters is more than good enough, most testers don't even bother trying to compare that; even the lowly 830B $5 meters typically hit within 1% of reference values. And the cheapo meters usually work just fine at wall-socket voltages and less. And if you hadn't noticed--a lot of "reviewers" don't test a meter by using it properly. They resort to abuse to try to show how inferior it is. The normal routine is to use everything on the wrong setting. This is total comedy to those of us who have owned cheap meters for YEARS and never once burned out even a single meter fuse. "Today we test this $25,000 oscilloscope. It reads just like it should, so now we will try using it under water, and then throw it down some stairs. Oh! It broke! Well then I guess it was just shoddy design..." And even at that--you can gain most of the benefits of expensive meter protection just by making your own leads with good fuses. There's electrician trade organizations that advise that all meter leads should have their own fuses, and most still don't. You can make your own pretty easy & cheap. -------- You can't protect against everything, but one common source of meter death is having the leads in the jacks and connected to power while turning the selector knob. If you get a meter that has jack shutters, then it is impossible to make the mistake of doing that. The Holdpeak 770HP is a meter that costs ~$35 and has jack shutters. Or the Gossen Metrowatt (Dave's beloved on eevblog) has them to. But it costs like $550. code:1. the lifetime warranty is not your life, it's the life of the product. Normally that is 5 years, and with commonly-damaged parts available for 2 more years. Sometimes they're nice and if they have parts, they'll fix a meter that is much older--but other times they want to charge way more than the meter cost, to repair it. And sometimes they just tell you it can't be repaired at all. 2. If you buy a China meter and you aren't in China, there is no warranty implied. It's only got a 1-year warranty, if bought and used in China.
|
|
#
?
Aug 4, 2017 23:57
|
|
|
Flukes are good but seriously overpriced
|
|
#
?
Aug 5, 2017 01:10
|
|
|
asdf32 posted:Guys I want to consider buying a reflow oven for our lab so we can properly replace large surface mount fets on existing boards. Suggestions?
|
|
#
?
Aug 5, 2017 02:06
|
|
|
I accidentally 120 V through a UNI‐T meter once. Dial turned to V, but plugs in the wrong sockets. The fuse didn’t blow. The tips of the probes did.
|
|
#
?
Aug 5, 2017 04:37
|
|
|
In my experience: I personally have 3 uni-ts. The tiny $10 one that fits in a pocket and doesn't do amps. Second meter is a 61E, a 22k count meter with dataloging, but mediocre input protection, trace clearance etc. Lastly a 139C that has good input protection, trace clearances, proper HRC fuse, and so forth. Otherwise it's a full featured but unremarkable 6k count meter. I like all 3 of them. I'll probably get a second 61E to do simultaneous voltage and current logging. For someone else's money I'd buy the fluke 87v. No question. The chinese flukes are basically unremarkable spec wise, so you still pay a premium for the fluke name, but they're also a quality meter(with the caveats others have mentioned). I'd have a difficult time selling management on buying a grey market import with a chinese box, but I wouldn't try to do it just to save a few hundred of their money on something that will be used for many years. The cheap domestic flukes (101 / 114 / 115 / 117 etc) are bad for electronics labs. They miss random settings because they're designed for troubleshooting industrial equipment in the field. The 117 for example, only has a 10A scale, no mA or uA. The 101 has no current measurement at all. The 116 only has a uA setting that's basically there to test oil burner igniters. In fairness, they do mostly have clues in their name, like electrician's multimeter, or meter for HVAC service, and so forth. Others though just say basic multimeter, and well, you can't get any more basic than what they give you. I've used Extech's at work. They're fine meters. Had nice large readable screens. Never had a reason to complain about them. I'd consider buying them if I needed to buy a bunch of meters and didn't have the budget for flukes. People do talk about QC issues but I've never run into it. (we had ~ 5 meters there though)
|
|
#
?
Aug 5, 2017 19:24
|
|
|
A UT210E is invaluable to have around to measure DC milliamps without breaking the circuit.
|
|
#
?
Aug 5, 2017 19:36
|
|
|
Aurium posted:In my experience: Thanks this is useful. I was thinking about the fluke 101's or 106's (which have current) besides the extechs. We have a good amount of better meters so I'm fine with a tier, half the time you just need anything and this purchas is intended to make it so no one is hunting around the lab in that situation. ANIME AKBAR posted:Why are you looking at reflow ovens then? Just get a PCB preheater like this and a decent hot air gun. With a setup like that I can pick up D2PAKs pretty quickly, once the whole board is brought to 150C. This might be perfect. I want our tech to be able to replace blown SMT fets (8x8mm packages) and let me run trials with alternate parts. She can remove and replace them with the heatgun but isn't confident the pad is solidly re-attached.
|
|
#
?
Aug 6, 2017 02:54
|
|
|
asdf32 posted:Thanks this is useful. I was thinking about the fluke 101's or 106's (which have current) besides the extechs. We have a good amount of better meters so I'm fine with a tier, half the time you just need anything and this purchas is intended to make it so no one is hunting around the lab in that situation. 106 is still a 10a range only meter. Here's a question for you, of the meters in your lab, how many have a functional current range setting, and how many have a dead fuse? If most are working, don't get anything without a uA and mA range. If most are dead, the fuse will be quickly blown on whatever you get, so it doesn't matter if it has a current range or not. It's almost nicer if it doesn't, as then there's no confusion. Just keep one or 2 with for trusted people, and lend them out. You can always add your own shunt to do current measurement to a setup, it's just a pain. Or improve education, which is good (but you'll still end up changing fuses).
|
|
#
?
Aug 6, 2017 03:40
|
|
|
Swapped out the cheap chinese mystery brand relay for a nice Polish one today. It's not worth tempting the magical house fire fairy and becoming a cautionary tale.
|
|
#
?
Aug 7, 2017 13:52
|
|
|
|
| # ? Jun 9, 2024 23:19 |
|
|
Aurium posted:106 is still a 10a range only meter. After a little more looking it seems the BK Precision is a good answer if current ranges are desireable. BK precision 2709B wins EEV's $100 shootout and looks solid all around for $89. Extech 330 wins the $50 shootout and has good features. I haven't decided what to do but we have some BK stuff in the lab too which has been fine.
|
|
#
?
Aug 7, 2017 15:07
|
|