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How best to control the brightness of Christmas lights (the incandescent sort)? I have this sneaking suspicion that pwm wouldn't work as well because they're not sufficiently responsive, but then maybe it'd work fine because they'd naturally smooth the pwm wave, so everything would work fine, but then again maybe that'd be hard on the bulbs and cause them to burn out sooner and and and I'd like to be able to control mine from a computer or arduino or what have you, and I'm just sorta brainstorming. On/off would be the most basic operation, but dimming would be cool.
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Dec 9, 2012 02:26
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| # ? May 9, 2024 09:22 |
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Bad Munki posted:How best to control the brightness of Christmas lights (the incandescent sort)? I have this sneaking suspicion that pwm wouldn't work as well because they're not sufficiently responsive, but then maybe it'd work fine because they'd naturally smooth the pwm wave, so everything would work fine, but then again maybe that'd be hard on the bulbs and cause them to burn out sooner and and and Triacs? http://arduino.cc/forum/index.php?topic=6970.0 Remember, one hand in your pocket! 
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Dec 9, 2012 02:31
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Incandescent? Use a dimmer. Oh, computer control. Use a dimmer with a stepper motor.
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Dec 9, 2012 02:31
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Bad Munki posted:How best to control the brightness of Christmas lights (the incandescent sort)? I have this sneaking suspicion that pwm wouldn't work as well because they're not sufficiently responsive, but then maybe it'd work fine because they'd naturally smooth the pwm wave, so everything would work fine, but then again maybe that'd be hard on the bulbs and cause them to burn out sooner and and and You can use a pure Voltage regulator. You can use PWM directly. Or if you need more power you can use a Triac.
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Dec 9, 2012 02:34
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sixide posted:Oh, computer control. Use a dimmer with a stepper motor. Ahaha, perfect.
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Dec 9, 2012 02:42
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Is there an IC with X number of resistors that I can use for a 7 segment display or do I just need to put in 7 discrete resistors? Something like a DIP-14 would be great, 7 resistors.
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Dec 9, 2012 02:44
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Martytoof posted:Is there an IC with X number of resistors that I can use for a 7 segment display or do I just need to put in 7 discrete resistors? Yes, you can get resistor arrays in a variety of configurations, including 7 in a 14-pin DIP. There's also display driver chips with current source drivers where you can set segment current with a single resistor. For example, at Digikey: http://www.digikey.com/scripts/dkse...16=6510&stock=1 Base Emitter fucked around with this message at 02:52 on Dec 9, 2012 |
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Dec 9, 2012 02:50
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Martytoof posted:Is there an IC with X number of resistors that I can use for a 7 segment display or do I just need to put in 7 discrete resistors? You can also get SIP packaged resistors with a common lead, like this:   which might save you some space vs. the DIP package, since 7 quarter-Watt resistors are going to take up exactly the same board area as a DIP-14 (unless you're doing surface mount in which case nevermind!)
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Dec 9, 2012 03:00
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Hey guys, what's a good multimeter with PC interface capabilities for under $150? Some people seem to love the $60 UNI-T UT61E but I'm also looking at Mastech M9803R and VICHY VC8145 bench top units. Any recommendations on these or anything I may have missed?
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Dec 9, 2012 03:51
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That Mastech looks like junk. There's no good reason to get a 2-wire only 3.5 digit benchtop meter. The Vichy has a pretty good feature set, but I can't speak to the quality/usability.
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Dec 9, 2012 04:16
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PDP-1 posted:You can also get SIP packaged resistors with a common lead, like this: My eee-lectronics knowledge is still maturing so I'm not sure how I'd use a common lead with a 7 segment display but I'm glad to learn these exist anyhow 
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Dec 9, 2012 04:29
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sixide posted:That Mastech looks like junk. There's no good reason to get a 2-wire only 3.5 digit benchtop meter. Yeah, scratch that one, I thought it was a $70 one I was looking at. For $130 it's not even close to worth it. (It's literally a handheld unit glued inside of a case. The Vichy seems to be a real bench top meter, at least. It looks like I can get one of those from one of my eCig suppliers in China for $140 (they'll throw one on a large order for me). I was wondering if anyone had recommendations other than these. I'm okay with a handheld meter as well. I want to get back into electronics and I need to pick something up with accurate resistance results for making these eCig coils. Data logging is a must as well, so I can run tests on batteries and eCig devices. Originally I was going to pickup a UT81B scope+multimeter, but I decided I'll just grab a DSO203 later on for scope duties. Edit: Oh, also the TekPower DT9602R is on the table as well. Looks decent and Amazon has it for $60 with Prime shipping.
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Dec 9, 2012 04:30
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It makes me mad when the doofuses at my work treat the Fluke meters & leads like poo poo because they're great and also expensive 
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Dec 9, 2012 05:09
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Sorry if this has already been asked, but how about inexpensive oscilloscopes? I'm just setting up a bench for my hobby projects, but all the good oscilloscopes seem to be hundreds of dollars. I found a few tiny hand-held ones on the cheaps, and a few that interface with a computer instead of having a screen which I might be able to work, but what about quality? Is there a huge difference between cheap oscilloscopes and expensive ones? Do you think I would be able to do the fairly basic stuff I need to do with a cheap (sub-$150) one? I just want to look at waveforms to see how my circuits are doing and to see what other circuits are doing for hacking stuff apart. For context, my specific first project I'm targeting is to build a Geiger counter, as it's not terribly complicated and it's cool enough to keep me interested, but I want to make sure the pulses aren't awful and noisy so I can read them with a microcontroller and I can't really think of a way to do that without a scope. Also I'd like to do some sound-based projects in the future. My dad is an electrical engineer and I grew up around this stuff and did it a bit for fun as a kid so I remember a lot of basic things about parts and how they go together, can tell my resistors from my capacitors and such, but I never really built anything terribly advanced on my own.
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Dec 9, 2012 05:13
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Might be worth keeping an eye on eBay, there are some great deals on oscilloscopes on there sometimes. Just be careful of shady sellers etc etc. Those pc interface ones just look pretty limited and it is nice having a discrete piece of test equipment not tethered to a pc.
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Dec 9, 2012 05:27
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priznat posted:It makes me mad when the doofuses at my work treat the Fluke meters & leads like poo poo because they're great and also expensive Don't worry, they're made so you can treat them like poo poo and they'll keep working just as perfectly. It does piss me off when people gently caress up the probes though, those aren't quite as tough. Unless you're talking about the bench meters, those are still durable but aren't built for nearly the same pounding and are even more expensive.
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Dec 9, 2012 05:33
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Oh yeah, they're very tough but it's just dumb, avoidable stupid poo poo that people do like just chuck em onto a bench or drop the probes on the floor. Still not as bad as how the soldering station gets treated though 
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Dec 9, 2012 05:40
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Parallel Paraplegic posted:Sorry if this has already been asked, but how about inexpensive oscilloscopes? I'm just setting up a bench for my hobby projects, but all the good oscilloscopes seem to be hundreds of dollars. I found a few tiny hand-held ones on the cheaps, and a few that interface with a computer instead of having a screen which I might be able to work, but what about quality? Is there a huge difference between cheap oscilloscopes and expensive ones? Do you think I would be able to do the fairly basic stuff I need to do with a cheap (sub-$150) one? I just want to look at waveforms to see how my circuits are doing and to see what other circuits are doing for hacking stuff apart. I also got one of these logic sniffers recently which helped me reverse engineer some spi stuff. http://www.seeedstudio.com/depot/preorder-open-workbench-logic-sniffer-p-612.html?cPath=75 There are a few different clients for it, some of which are pretty nice. Only downside is pretty low memory for storing samples.
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Dec 9, 2012 05:58
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Are you running the custom DSO Quad firmwares? I hear they help tremendously!
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Dec 9, 2012 06:03
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I had a nice Tek TDS-420A but something in it failed and the readings are all wrong and the POST reports acquisition board failure. The only fallback scopes I've got access to are all 30 year old Teks that are in horrible shape. If I throw the probes into ground coupling mode the reference waveform is seriously curved. I'm actually holding onto the nice Tek scope in case I decide to get it fixed one day. It's probably more scope than I'll ever actually need. It's really hard to go back to something basic after you've been spoiled though Peeps, how do you like the logic sniffer? I sort of want to get my hands on that one you picked up. some kinda jackal fucked around with this message at 06:34 on Dec 9, 2012 |
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Dec 9, 2012 06:32
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I think I'll grab the TekPower DT9602R for now. It's only $30 on Amazon and has an RS-232 interface on it. Turns out it uses the same protocol as a Voltcraft 820, which is good for me because I can use a nice little Mac app called VC 840 Recorder to plot all the data right to a TSV file. (It also works with QtDMM, so if I compile the latest version of that for OS X I'd really be set.) Might grab that Vichy on my next order from China.
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Dec 9, 2012 06:55
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Parallel Paraplegic posted:Sorry if this has already been asked, but how about inexpensive oscilloscopes? I'm just setting up a bench for my hobby projects, but all the good oscilloscopes seem to be hundreds of dollars. I found a few tiny hand-held ones on the cheaps, and a few that interface with a computer instead of having a screen which I might be able to work, but what about quality? Is there a huge difference between cheap oscilloscopes and expensive ones? Do you think I would be able to do the fairly basic stuff I need to do with a cheap (sub-$150) one? I just want to look at waveforms to see how my circuits are doing and to see what other circuits are doing for hacking stuff apart. If you look at all those ebay mini scopes you'll see that they're built into old phone/mp3 player cases. This tells you everything you need to know about the quality. Pretty thorough review of a typical one here: https://www.youtube.com/watch?v=3im97Z7ceNI
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Dec 9, 2012 17:47
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Martytoof posted:My eee-lectronics knowledge is still maturing so I'm not sure how I'd use a common lead with a 7 segment display but I'm glad to learn these exist anyhow Oh yeah, your display probably already has a common lead so that resistor package won't do much for ya. Unless of course you only ever want to turn every segment on or off in unison in which case it's absolutely perfect.
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Dec 9, 2012 19:21
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I think the last time I got on a scope-shopping kick, I was looking at Tek 2213s on eBay? I don't want to drop more than a hundred until I can spend $1k or so on a quality one that will last me a long time. I wouldn't even rate one of those little mp3 player scopes for anything serious. Those little LCD displays are not known for their response time.
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Dec 9, 2012 20:27
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The 2213 is actually one of the misaligned scopes that I have. I wonder if there's any way to adjust the plot. It seriously curves almost 1/2 a div over the range of the scope when it's ground coupled.
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Dec 9, 2012 20:33
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So I'll probably need to save up for something actually good or it's a crapshoot I take it (though I will look into that DSO-203 and the logic analyzer, thanks peepsalot!) Oh well, maybe I can borrow one of my dad's ancient analog CRT scopes while I'm waiting, at least I can pretend I'm a 1950's mad scientist 
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Dec 9, 2012 21:25
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I've heard good things about some Rigol scopes; I definitely wouldn't recommend any of those pico/tiny scopes though; IMHO, they are more toys than actual tools. Personally I got a LT344L from LeCroy under some lucky circumstances, so I am pretty solid for awhile. It's not very portable though; my dream scope would be one of Tektronix's MDOs like a MDO4104-3. 1GHz analog scope + 16 channel logic analyzer + 50kHz-3GHz spectrum analyzer for "only" $25,000. I've been skewed shopping for scopes recently as I've been trying to quote a new serial analyzer for work / PCIe 3.0 stuff, and they start at around $250k. So uh I guess for Hobby stuff, Rigol is pretty good and not crazy expensive. A good oscilloscope is a great investment.
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Dec 9, 2012 21:39
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I bought this USB scope back when I was getting started. It's $250, but they offered a discount for students when I bought it which made it $200. I still find it quite handy as it's an oscilloscope and logic analyzer. Your best bet would probably be to save up and get one of the Rigol scopes for around $400.
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Dec 10, 2012 01:08
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Rigol is on par with any of the big-name "economy" scopes. Difference is the Rigol costs 25% as much or less.
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Dec 10, 2012 02:05
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sixide posted:Rigol is on par with any of the big-name "economy" scopes. Difference is the Rigol costs 25% as much or less. Rigol seems to use all name-brand components, and are competently designed. Doesn't one of the major scope companies sell rebranded Rigol scopes as their economy models?
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Dec 10, 2012 02:16
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Slanderer posted:Rigol seems to use all name-brand components, and are competently designed. Doesn't one of the major scope companies sell rebranded Rigol scopes as their economy models? Agilent does, see the 1000 series. Even the part numbers are identical.
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Dec 10, 2012 02:26
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Cool, I'll look into Rigol then. I talked to my dad today, and he said that while he did have an old spare analog scope I could have, it was in pieces as he was replacing the control systems since they were "noisy, worn and getting a bit oxidized with age". He has the new parts, just hasn't gotten around to putting them in yet, so I guess that's out at least for now. Anyway, thanks for your help guys.
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Dec 10, 2012 03:03
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Slanderer posted:Rigol seems to use all name-brand components, and are competently designed. Doesn't one of the major scope companies sell rebranded Rigol scopes as their economy models? I'm pretty sure I told this story before, but a while back an engineer from Rigol came to our school trying to sell us their scopes, and he stated in no uncertain terms that all of their scopes are direct ripoffs of Agilent models. Many employees, including himself, were headhunted by Rigol from Agilent. And to prove this he wore his old Agilent employee badge and shirt while he was doing his pitch to customers. For Rigol, ripping off Agilent is a point of pride. And the thing is the quality of the components and craftsmanship is largely the same. So there's really no reason to buy an Agilent scope if you can find a Rigol equivalent, if you want to save money.
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Dec 10, 2012 12:49
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I always found the UI on the lower-end Agilent scopes to be really atrocious and counter-intuitive compared to what Tek offered. I think they've gotten better recently, but I really loathed having to use the Agilent scopes that were in one of the labs. Would have rather just had classic TDS3034 or similar. Interesting story about that engineer though, I didn't know that was the case.
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Dec 10, 2012 15:40
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I considered Rigol when shopping for my hobby scope but was a little wary since I'd never seen or used one one in person. They do indeed look very similar to Agilent and I think for the money in the 50MHz-100MHz range are probably the way to go. According to that EEV blog guy the 2 channel 50MHz version can be unlocked via firmware to go to 100MHz, so that's nice. I ended up with a factory refurb Agilent DSO1024A. The user interface is exactly the same as the 6000 and 7000 series I've used so it is very familiar. I can't compare it to the really high end models Agilent sells their refurbs directly from their Malaysian factory over ebay. The seller name is "agilentused". My scope came in an Agilent box with Agilent paperwork/bill of sale and has the same service contract and cal options as any new scope. It was under 50% of MSRP, looked brand new in every way, and came with a full set of 4 new 300MHz probes. Many of the engineers I know including the contract guys buy their personal and business stuff through this channel.
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Dec 10, 2012 16:56
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Bruinator posted:According to that EEV blog guy the 2 channel 50MHz version can be unlocked via firmware to go to 100MHz, so that's nice. I think one of the later firmwares disabled that so if you get one now you'll have to downgrade the FW.
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Dec 10, 2012 18:13
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This doesn't seem quite right to me. I googled up a water detection circuit/arduino thingie, built it, and stuck the probe in the reservoir under my Christmas tree. It works, but after a while it seems to go wonky. What's wrong with this?  I feel like that resistor is in the wrong place, and maybe the or the probe/sensor is "backwards"...that is, I'm thinking if +5V and GND were swapped in that drawing, it'd be more what I expect. Or maybe the resistor should be between the fork and the sensor pin, rather than between +5V and the fork?
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Dec 10, 2012 18:28
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Bad Munki posted:This doesn't seem quite right to me. e: Try measuring the ohms of the water without the rest of the circuit attached. longer and closer together probes in the water would also probably help. peepsalot fucked around with this message at 19:16 on Dec 10, 2012 |
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Dec 10, 2012 19:13
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Get a float switch, shrub.
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Dec 10, 2012 19:14
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What value is that resistor? In theory, it should work, IF you have a significantly lower resistance through the water than you do through the resistor. Can you hook an ohmmeter up to your two wires going to the reservoir, and give us a ballpark resistance reading when it's full and then when it's empty (should be basically infinite on the latter)?
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Dec 10, 2012 19:15
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