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Solder paste is: It's little balls of solder in a sea of tacky flux, normally applied with a stencil and squeegee. You don't want this for hand through hole work. You want a wire solder with a flux core. Once you apply the wire solder and it cools back down (or if it stays hot long enough), all the flux will boil out and the remaining metal will oxidize. Reflowing that won't work well with just heat, so if you make a mistake in your initial joint, you'd apply a flux pen (or syringed liquid, but pen is easier) so that there's new flux that will reduce the oxides off when you apply the iron so things flow well. If everything's sizzled off after you apply the iron, it's probably not going to flow any better than it has already (unless something's not hot enough), so back off, reflux, and try again. There are a few general categories of electronics fluxes available (packaged either in the core of wire solder, the liquid in a pen/syringe, or the sea in solder paste). You generally want Rosin, Mildly Activated (RMA) or no-clean. RMA residue should get cleaned up with 99% IPA afterwards or it will eventually corrode parts. No-clean you can leave on or clean up, it's just sticky/ugly. The categories you probably don't want are: Rosin Activated (RA) is too aggressive/corrosive, unactivated rosin (R) is too weak, and water soluble isn't very hobbyist suitable (it is aggressive but removable with water powerwash equipment you don't have) If you're building something up, especially if you're not super confident in your technique yet or it's a small/tricky joint, test it as you go! If you have a schematic handy or it's an obvious trace on the outside of a board, you can use a multimeter to measure a path that goes through the part you just added or from a pad to the part side you just soldered. e.g.  You can poke those with a meter set to beep on continuity and check that the joint is connected right away Foxfire_ fucked around with this message at 07:34 on Nov 21, 2021 |
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Nov 21, 2021 07:31
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petit choux posted:While I was kinda mulling the idea of lasers I found this on ebay: So I'd forgotten I'd ordered this a little over three weeks ago. Arrived earlier this week, put it together over about two hours this afternoon, very relaxing and meditative (maybe it was just the soldier fumes) Plugged it in and worked on the first try. For such a simple device there's an alarming amount of latency, maybe an eighth of a second Weirdly in the bottom center there's four pins that there was nothing to plug in, I did some digging and apparently this is 5v + serial in and out? I wonder if this is supposed to be a poor man's line out for use with recording equipment or what. Haven't had time/energy to attach a serial device to it to read the output. I guess this is a clone of another device, they just cut corners to make the breadboard 2 pieces to cut costs If there's any other stuff out there like this, I'd be interested, I haven't assembled electronics like this since I built an electric guitar fuzz pedal probably 14 years ago
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Nov 21, 2021 11:48
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Hadlock posted:So I'd forgotten I'd ordered this a little over three weeks ago. Arrived earlier this week, put it together over about two hours this afternoon, very relaxing and meditative (maybe it was just the soldier fumes) Having 5V + serial is usually there as a debug header or for programming the chip, probably not meant for end-user use.
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Nov 21, 2021 12:02
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Foxfire_ posted:There are a few general categories of electronics fluxes available (packaged either in the core of wire solder, the liquid in a pen/syringe, or the sea in solder paste). You generally want Rosin, Mildly Activated (RMA) or no-clean. RMA residue should get cleaned up with 99% IPA afterwards or it will eventually corrode parts. The last Macrofab Engineering Podcast was a whole episode on solders and fluxes, how to clean them up afterward, and how not to mix flux types: https://macrofab.com/blog/mep-ep303-tip-resurrection-cream/
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Nov 21, 2021 14:26
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Okay, Imma just try a couple different types for starters. So very sorry I've been using inferior flux all these years, and my only excuse is I've been mostly doing this sort of in solitary and haven't talked to people about it much until I started doing it again last year, so I haven't had many mentors or examples to learn from till now. I'm still slowly getting equipped and learning, thanks to you guys and dolls. Hadlock posted:So I'd forgotten I'd ordered this a little over three weeks ago. Arrived earlier this week, put it together over about two hours this afternoon, very relaxing and meditative (maybe it was just the soldier fumes) There's a small corps of ingenious people in Hong Kong, Tokyo, all over the place really, just crazy over DIY stuff, they sell cute little projects all the time. You can surf ebay or etsy for a lot of cool projects, particularly in the music related stuff. And I'd recommend the one I just did, the "Altura" a MIDI theremin from Zeppelin Design, which is really f@#$ing neato. And it's worked with every cheap Casio keyboard with a MIDI jack that I've tried so far so you don't really have to own a lot of MIDI related gear to try it, just a cable and a plastic keyboard that has MIDI in. And another one that caught my eye is a DIY synth called the Chernobylizer, it looks fun and they say it sounds great.
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Nov 21, 2021 16:42
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Chernobylizer makes some pretty juicy noise but I'd mod it so I don't have to keep my fingers on the touch pads to get those demon noises.. put some switches in instead so you do other stuff while it screeches.
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Nov 21, 2021 16:57
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petit choux posted:Okay, Imma just try a couple different types for starters. So very sorry I've been using inferior flux all these years, and my only excuse is I've been mostly doing this sort of in solitary and haven't talked to people about it much until I started doing it again last year, so I haven't had many mentors or examples to learn from till now. I'm still slowly getting equipped and learning, thanks to you guys and dolls. FWIW that's a pretty big deal and you should be pleased at your progress imo. When I learned to solder it was first in robot club after school and then later at my first job. I think having someone else pick out decent equipment and materials and also be able to watch and correct you live is huge. Soldering is definitely the sort of thing that's about 1000x easier to learn from live instruction than it is from reading. Even then I still had to go back and touch up boards regularly for a long time.
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Nov 22, 2021 15:21
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Forseti posted:FWIW that's a pretty big deal and you should be pleased at your progress imo. When I learned to solder it was first in robot club after school and then later at my first job. I think having someone else pick out decent equipment and materials and also be able to watch and correct you live is huge. Soldering is definitely the sort of thing that's about 1000x easier to learn from live instruction than it is from reading. I am sooo pleased, communities like this one weren't so easy to find before the internet. And Anderton and Mims were my only guiding lights. The guys at Electronics Plus just cracked jokes about dummies trying to do electronics with hardware store equipment, I laughed back at them when they went out of business.
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Nov 22, 2021 15:36
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petit choux posted:I am sooo pleased, communities like this one weren't so easy to find before the internet. And Anderton and Mims were my only guiding lights. The guys at Electronics Plus just cracked jokes about dummies trying to do electronics with hardware store equipment, I laughed back at them when they went out of business. Wrote that right after waking up so hopefully I didn't come across as calling you an ingrate or anything like that. I'm just prone to focusing on what I can't do/have trouble with myself, so I like to point out positive progress to other people when I think I see it. Agree on this thread, it's a fantastic place with a huge amount of combined skill and more importantly a willingness to help and teach others!
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Nov 22, 2021 16:47
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Forseti posted:Wrote that right after waking up so hopefully I didn't come across as calling you an ingrate or anything like that. I'm just prone to focusing on what I can't do/have trouble with myself, so I like to point out positive progress to other people when I think I see it. Yup, lots of discussion that's sort of over my head but still willing to address my level now and then, it's really helpful. So I've removed the solder sucker from my list for now, and getting these: quote:60 ml. / 2 Oz. KESTER 951 No Clean Soldering Solder Liquid Flux Reflow
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Nov 22, 2021 16:57
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petit choux posted:Yup, lots of discussion that's sort of over my head but still willing to address my level now and then, it's really helpful. Personally, I REALLY like my headband magnifier and use it all the time: https://www.amazon.com/gp/product/B07M7H3P95. There are a lot of people who don't like them though, but maybe worth considering a pair to try out. I have the glass lens ones for $20 and like them a lot. I mostly use the 1.5X or 2X lenses as the depth of field narrows as your step up the magnification and then also still use a 10x loupe for detailed inspection after.
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Nov 22, 2021 17:03
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Forseti posted:Personally, I REALLY like my headband magnifier and use it all the time: https://www.amazon.com/gp/product/B07M7H3P95. There are a lot of people who don't like them though, but maybe worth considering a pair to try out. I have the glass lens ones for $20 and like them a lot. I mostly use the 1.5X or 2X lenses as the depth of field narrows as your step up the magnification and then also still use a 10x loupe for detailed inspection after. Okay well as of yet I'm still reeling from the improvement I got just by wearing my 2x dollar store readers and this armature lamp with a lighted magnifying lens. Will keep that in mind.
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Nov 22, 2021 17:07
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petit choux posted:Okay well as of yet I'm still reeling from the improvement I got just by wearing my 2x dollar store readers and this armature lamp with a lighted magnifying lens. Will keep that in mind. Oh I didn't realize you had that, probably no reason to get a headband magnifier then. Also I never thought of dollar store reading glasses, that's a fantastic idea honestly.
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Nov 22, 2021 17:13
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Forseti posted:Oh I didn't realize you had that, probably no reason to get a headband magnifier then. Also I never thought of dollar store reading glasses, that's a fantastic idea honestly. Yeah, well my vision has been getting worse. My issue has been once again to admit to myself that I actually need glasses. Once I got those I saw sooo many flaws in my solder joints that I hadn't seen before. Much better than the magnifying glass by itself.
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Nov 22, 2021 17:19
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My favorite thing about wearing glasses is not noticing your vision continuing to get progressively worse (after all, I'm wearing glasses, so this blurry mess must just be how the world objectively looks to everyone) Eyes suck.
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Nov 22, 2021 17:27
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For me it's not my overall prescription getting worse, it's the "I can't focus on stuff close to my face anymore" that happens in one's 40's. Which led to a year of constantly taking my glasses off to look at my phone before I finally gave up, admitted I'm old now, and got progressives.
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Nov 22, 2021 17:31
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petit choux posted:Okay well as of yet I'm still reeling from the improvement I got just by wearing my 2x dollar store readers and this armature lamp with a lighted magnifying lens. Will keep that in mind. The nice thing about a headband magnifier is that it gives you depth of vision, really helps not burning your fingers or plastic on the pcb when soldering. Mine was €8 and it's so good (nice LED light as well) that I don't even consider something more expensive
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Nov 22, 2021 17:41
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For parts inspection another excellent and very cheap option is a simple clip-on magnifying macro lens/microscope for your phone’s camera; it’s not practical to use one while actually soldering, but i was amazed at the detail level you can capture when you combine a 10x aliexpress microscope with a modern iphone camera’s additional zoom capacity. Being able to take decent in-focus pictures with that setup is incredibly useful for getting feedback/advice on your teeny little SMD soldering jobs- it doesn’t replace having a hands free magnifier for actual work, but it’s still very useful in a slightly different way. here’s an example from a while back, i wanted to know how typical lil ceramic disc capacitors were fabricated, so i cut one open and took some microscope pics. phenomenal results for a $7.50 cheap phone accessory, much better zoom factor and better legibility than using a traditional loupe, etc Ambrose Burnside posted:friday night benchwork: (crudely) cut some generic sub-~500pF ceramic disc caps in half with a fine-toothed saw to photograph their innards at 10x magnification, b/c i Had To Know For Sure Ambrose Burnside fucked around with this message at 20:19 on Nov 22, 2021 |
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Nov 22, 2021 20:12
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Ambrose Burnside posted:For parts inspection another excellent and very cheap option is a simple clip-on magnifying macro lens/microscope for your phone’s camera; it’s not practical to use one while actually soldering, but i was amazed at the detail level you can capture when you combine a 10x aliexpress microscope with a modern iphone camera’s additional zoom capacity. Being able to take decent in-focus pictures with that setup is incredibly useful for getting feedback/advice on your teeny little SMD soldering jobs- it doesn’t replace having a hands free magnifier for actual work, but it’s still very useful in a slightly different way. Yeah, I've been looking at those too, glad to see somebody uses them.
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Nov 22, 2021 20:44
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There are 10x loupes out there too, with a little ring of leds to illuminate the surface. I bought it for cleaning my camera's sensor but it turns out it's useful for lots of things.. like solder joints.
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Nov 22, 2021 20:58
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petit choux posted:So I've removed the solder sucker from my list for now, and getting these: Add some braid/wick with flux, use it to remove excess solder. I generally like it more than a solder sucker but it is slower if you have to do a bunch of holes.
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Nov 23, 2021 03:28
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taqueso posted:Add some braid/wick with flux, use it to remove excess solder. I generally like it more than a solder sucker but it is slower if you have to do a bunch of holes. I think I have some of that. Never really seen anybody use it though, I think I better watch some videos.
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Nov 23, 2021 03:31
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my general comparison reckons in this regard: - Solder wick is great for cleaning up surface solder, small/irregular deposits, and for anything where its heat- and capillary-based mode of action works well given your tools and the part. Solder suckers are ideal for removing large amounts of solder and especially for clearing tinned thru-holes like on PCBs and protoboard, or anywhere else you can get a good nozzle seal so the suction action is effective. - Solder wick is very thorough and leaves little to no residue when used properly; solder suckers tend to only clear *most* of the solder, enough to free a pin from a thru-hole, but not clean like from the factory. - Solder wick is a consumable and can only hold so much solder per linear length, so doing a lot of work with it or hitting big balls of solder can go through a roll awfully quickly; a decent solder sucker should work for years with a little maintenance, with the only real consumable being the tip, unless it's a real low-quality sucker (get one with a soft silicone tube tip and not the hard plastic ones, theyre awful and fall apart quickly) - Solder wick is fluxed, usually a no-clean flux, which introduces a need for fume extraction if you're working indoors, the fumes from that stuff are nasty compared to rosin. Solder suckers don't use a fluxing action so that's not a factor there if I'm removing solder, I usually use both in concert, or at least have both on hand so I have the right tool as required. They have their own niches and neither can do everything effectively. That said, solder wick is a cheaper place to start and will be fine if you're not trying to strip entire PCBs or desolder bigass heatsink thru-hole parts with enormous heatsink soldered joints. Watch some videos on how to do it properly, you need to make good use of the soldering iron heat for the wick to, you know, wick.
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Nov 23, 2021 23:39
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Ambrose Burnside posted:my general comparison reckons in this regard: Hey, thanks much for yet another very instructive post!
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Nov 24, 2021 03:31
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I put some extra flux on the solder wick. Tip from Mr. Carlson.
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Nov 24, 2021 09:04
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That's a good tip for anything where you need an immediate and thorough thermal bridge, yeah. It isn't really about the fluxing action with that initial bit of flux, the wick will be plenty active when the entire worksite comes to temp, it's to provide a wetted junction between the iron and the workpiece that will conduct heat efficiently.
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Nov 24, 2021 17:06
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I have a commercial incubator that I picked up from Craigslist whose inner chamber has a peltier and an 80mm 12VDC computer fan to ensure even temperature. The fan has been smelling like burning for a while, and recently stopped working. When the door latch is closed (= the fan is supposed to be blowing), the fan leads oscillate between 18v and 13v. I suspect that sending 18v to a 12v fan is why it smelled like burning. I don't know why that's what they are using to power a 12v fan, maybe the control circuitry has gone haywire or something, but it seems to me that I could just solve the symptom with a voltage divider circuit. 10K and 20K resistors should give me 12v on the high end and 8.5v on the low end which should be fine. I still need to call the manufacturer and see if they will send me a repair schematic or datasheet or something, because I'm certain it came with a 12v fan and I dont understand why it's sending 18v, but if they tell me to pound sand, is my plan a fine one?
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Nov 27, 2021 22:02
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It's also possible that some sort of voltage regulator is failing if you're getting multiple voltages. You should definitely investigate further than just cobbling together something that fits the current situation, because it could get worse.
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Nov 27, 2021 22:09
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Voltage dividers aren't appropriate methods to get power supply voltages, it won't work. There's a chance that the 18V you're seeing is from the motor windings getting a bunch of energy and then the fan being broken, it just dumps the energy back onto the voltage rail. Try disconnecting the fan and then measuring the power supply. The burning smell is a likely indicator that the fan needs to be replaced anyway - If the power supply actually is bad, then that bit will need to be replaced, too. A lot of decisions rest on that, so report back and we can advise if you like.
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Nov 27, 2021 22:16
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I already disconnected the fan. There is nothing connected to the fan power leads but my multimeter probes. In order to get at the power supply, I have to pull the whole cover off of the 30 liter box and its kind of a big todo. Also it takes in 120V AC and uses spade connectors, so I'm not crazy about reaching in at odd angles to try and get my probes on the right spades while it's live. Last time I opened it up I couldn't figure out how to actually make it easy to work on. I'm in the middle of a project right now so maybe I'll come back next week or so with pictures and possibly diagrams and we can figure things out. Thanks thread.
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Nov 27, 2021 22:56
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I'm currently building up a simple circuit to test from one of Forrest Mims' project books, the Photophone. It uses a reflective diaphragm mounted to a tube to bounce sunlight at a photocell and then amplifies the signal to output through a speaker. I left off the audio amplifier stage for now, just trying to see if I can actually get some sort of signal and see it on my oscilloscope for the moment. I did have a question about the feedback though, I'm used to seeing a voltage divider to set the gain but there is only a single 1M resistor for feedback here and I'm wondering why just a single? My suspicion is that this behaves more or less like open-loop but helps keep the circuit more stable? Or maybe you'd have to figure out the output impedance of the LED + Capacitor if you actually wanted to calculate the gain? I haven't tested it yet, I just had these questions as I was transferring the design to KiCAD. If it matters, the original design from the book is using a 741 and not an LM358, but I figured I should keep the rest the same as a starting point. I'm also using a rando red LED I picked from my parts pile, so not sure how well that will work. I did hook the scope probes straight to the LED and could see it reacting a little to a red laser as well as a bright white flashlight. I do have phototransistors somewhere I think, but not an actual photocell, but I've been fascinated by pressing LEDs into service in non-standard ways so I thought I'd give it a try.
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Nov 29, 2021 01:07
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Forseti posted:I'm currently building up a simple circuit to test from one of Forrest Mims' project books, the Photophone. It uses a reflective diaphragm mounted to a tube to bounce sunlight at a photocell and then amplifies the signal to output through a speaker. That configuration of opamp is a differentiator: https://www.electronics-tutorials.ws/opamp/opamp_7.html I'd guess it's using that because you want it to react to changes in voltage rather than absolute value, cuz otherwise there'd be a bias voltage just due to light constantly hitting the LED.
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Nov 29, 2021 02:21
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Shame Boy posted:That configuration of opamp is a differentiator: https://www.electronics-tutorials.ws/opamp/opamp_7.html Ahhhhh ok, that makes sense. Thanks! I didn't realize that was a particular topology, I just saw it as an ac coupled input and then everything else.
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Nov 29, 2021 02:28
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I have done exactly what you are trying to do, and it looked like this: My gut feel on the different input, relating to the tiny LED current being proportional to lux hitting it, is: - The input to the op amp on mine is held to ground, unless a small current is being generated by the LED. Then it will be pushed below ground slightly, giving the op amp a positive output. The effect of this is that it will always have a small signal. - Input to your will only effect on changes to light output. So the diode goes from 100uA to 200uA say, and then there will be a slight peak on the output until the capacitor catches up, and then normalise. This is my initial read of the two schematics. I'm a little drunk and shooting from the hip though so maybe I am wrong!
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Nov 29, 2021 02:30
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I'm going absolutely insane trying to recreate papers in SPICE here. The paper I'm trying to recreate is High-Frequency Resonant SEPIC Converter With Wide Input and Output Voltage Ranges which is MIT open access. The first thing they try to do is get a resonant diode setup. One tank, no active components, simple right? They even give sample component values. I got the spice model for the diode they specify from the manufacturer's site. Here's their setup:  And here's their nice result:  Here's my setup, with my results:  I even went wild with .param and produced a large range of graphs in which I was very good at finding parameters entirely out of phase and none at all even close to 0 degrees, even with theoretically ideal values for the resonant tank at 20MHz:  Any idea what I'm doing wrong? I tried switching to a model diode, editing the model to use their assumed parasitic cap, and still just absolutely nothing. The model for the diode I've been using is quote:*SRC=DFLS230L;DI_DFLS230L;Diodes;Si; 30.0V 2.00A 5.00ns Diodes Inc. Schottky
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Nov 29, 2021 22:43
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oh my GOD the ltspice current source component has its arrow pointing down, and I assumed it would be symmetrical since it's just a sine wave around 0 and ignored it, but then after posting I noticed it was the other way in the paper and sure enough:
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Nov 29, 2021 22:47
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Even if it's a sine wave, current is still directional.
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Nov 29, 2021 23:28
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Re: LED as photodiode My initial attempts to see something with the circuit I posted (except I grabbed a 1u cap instead 0.1u because that's what I had on my bench. I think the effect of this will just be that it responds to slower pulses e.g. lower bottom frequency?) didn't really do much with my first LED, a generic looking red one with red plastic. When hooked directly up to the scope, I could see light affecting it but mostly I could see the 60 hz noise being picked up by the probe. Searched around a bit and found this fantastic article, which also turned out to be from Forrest Mims (that guy a big deal or something?  ) and he's using a slightly different circuit there, which maybe is more sensitive? The one I used is from the book and the book calls for an actual photodiode. I did pick up two handy things though, the first is that he's testing it with a multimeter in current mode and the second is that the LED he's showing has a clear lens instead of filtered. I fished around in my LED pile testing them with the current mode and found one with a clear lens that emits an orange light that works MUCH better (like 60uA vs 0.4uA) and it is working just fine with the circuit as shown (but with the 1u cap as mentioned).So maybe the clear lens LEDs are in general better for this purpose or maybe it's just happenstance. From what I've read, it sounds like LEDs emit a slightly different wavelength than what their peak sensitivity is as a photodiode, so maybe the filters mess with that. Maybe it's just that I'm testing with a white light and a clear lens lets through a LOT more photons. Not sure, but if anyone else is trying this, it might be good to have a pile of LEDs to pick from. I also have some RGB LEDs that are just three different colored LEDs in the same package, each with their own leads. I may have to experiment with that, because I think that could actually be used to determine the color of light hitting it too, basically like a single pixel from an image. Now to go ahead and prototype out the rest of that photophone circuit and give it a try
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Nov 30, 2021 19:36
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Forseti posted:When hooked directly up to the scope, I could see light affecting it but mostly I could see the 60 hz noise being picked up by the probe. Did you not hook up the ground lead or something? There's no reason the scope should be picking up 60hz noise...
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Nov 30, 2021 19:41
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Shame Boy posted:Did you not hook up the ground lead or something? There's no reason the scope should be picking up 60hz noise... I think it was just not getting enough excitation to conduct much of anything. With the more sensitive LED in place, it still shows noise when the light is off of it but as soon as I shine the light at it, it calms down to a nice clean trace. I don't have any sort of bypass resistor or anything to let current through any other path than the LED itself. I also have the lovely $20 probes and the one I use all the time is starting to get pretty janky and sometimes doesn't connect solidly (electrically speaking). Or that's what I think is going on anyway. It's definitely starting to get a divot worn in the plastic where the metal hook pulls whatever into it. I should probably get some real HP/Agilent leads for this thing sometime.
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Nov 30, 2021 20:16
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