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Stack Machine posted:The datasheet shows better efficiency for 770kHz at vin=24V/vout=12V. Lower switching frequencies help with efficiency by reducing switching and gate drive losses. I wonder if they recommend the 2.1MHz version because it's the one that's not right in the middle of the AM broadcast band while showing more measurements from the 770kHz version because it tends to perform better. Oh you're right, I think I got some kinda optical illusion looking at those charts cuz if I don't look closely the 2.1Mhz one seems higher, but I think that's because it's kinda angled up while the other one is more flat, huh.
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Sep 19, 2023 14:19
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Also it seems octopart fixed that weird-rear end problem I was having before where everything in a category was getting AND'ed instead of OR'd so that's good, I was terrified that was deliberate for some godawful reason.
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Sep 19, 2023 14:25
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I need some guidance on how to make LED strips light up in a pattern. I bought this 12 volt 4 channel relay but I realized I have no idea how to use it. Is this the right thing I need? I just want three LED strips to blink in sequence and then start over, but this relay didn't come with instructions and I have no idea how everything hooks up. I can tell where the power lines go in because they're labeled with DC+ and DC-, but the relays just have labels for NO, COM, and NC. I also have no idea what IN1-4 are for. As you can probably tell I'm in way over my head.
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Sep 20, 2023 16:20
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Deadite posted:I need some guidance on how to make LED strips light up in a pattern. I bought this 12 volt 4 channel relay but I realized I have no idea how to use it. Is this the right thing I need? You have half your project there, so that's good. This is what would turn the LED strips on and off. You'd connect +12VDC to DC+ and all of the COM terminals. Connect 0VDC to DC- and the - of all your LED strips. Connect the + of each of your LED strips to the NO of each relay. Now you just need to put +5V at each of IN1 - IN4 in turn, and each LED strip will turn on in turn! That's the second half of the project. Do you feel comfortable with an arduino or other small microcontroller, or are you looking for something off-the-shelf?
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Sep 20, 2023 16:33
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Thanks, the diagram really helps clear up how this all works. Is there an off-the-shelf solution for what I'm trying to do? Adding a microcontroler this is going to make this bulkier than I'd like it to be. There's this sign that Target sells that doesn't essentially the same thing I want, but the relays are in a much smaller box that is about 2.5 inches by 2.5 inches. I just have no idea what is in that box or where to get them. https://www.target.com/p/18-34-faux...82/-/A-87296333
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Sep 20, 2023 17:14
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Something like this Adafruit ItsyBitsy is just the ticket then. Smaller than your four relays. This would be 100% of the code you need to run the thing: code:
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Sep 20, 2023 19:37
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I’ve been using this old guy for quite a few years, it’s served me extremely well. But, for obvious reasons, replacement parts are less than available these days. Or at least, parts that are clearly correct replacements. Specifically the ceramic heating element. There may be parts available, but they always come with huge maybes attached as to whether or not they’re actually the right specs. A while back, the ceramic sheath on the heating element cracked. It’s limped along for a bit in that state, but the thing is slowly crumbling more and more to dust. Any recommendations for a good replacement? Figure this is an opportunity to go with something of a more typical brand, and possibly upgrade as well. Should I also consider adding a hot air station to my bench? I see various price levels for those, have used one in the past and it was great, but I’m not sure at what price they actually become worthwhile.
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Sep 24, 2023 22:43
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I've been using one of the basic Weller units (a WE1010NA or something similar) that I got along with a set of five different tips for like $175 and really like it for general work. I have tried Aoyue and Hakko units which are cheaper but they're not nearly as nice. A soldering station is such a commonly used tool that I figure it's best to spend a bit more to get something decent.
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Sep 24, 2023 23:05
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Any thoughts on the Rigol dho804? I have an ancient lecroy 9310a but it's the size of a carry on suitcase and has some developing faults so I'm thinking of just getting something hobbyist grade. Use case will primarily be vintage computer "repair" and tinkering and maybe some hobbyist esp32/arduino stuff. The protocol decoding feels really appealing to me for some reason. I'm almost certain that the 70mhz model is fine for what I need and knowing Rigol it'll probably be unlockable to 100mhz variant through software. It's probably way overkill but every time I pull out the lecroy I find myself wishing for something smaller and more modern and I guess right now I'm in the position to pull the trigger. Don't think I've ever really needed a logic analyzer or arbitrary waveform generator so no real desire to step up to the 900. In all honesty I could probably get away with a crappy USB scope for all my use cases but I'd rather not have to tether off a laptop.
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Sep 25, 2023 13:22
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I've watched a couple of Dave's videos on it, though not the full length video in that link. Seems to be the new top contender for hobbyist level machine. I would sure love to replace my old Tektronix with it just so I don't have to have a dedicated area for it. He also confirmed that it can be unlocked to the 100MHz version.
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Sep 25, 2023 16:16
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oh yeah I always forget he probably has something to say about osc's. Thanks, I'll go through that! e: Pulled the trigger but they're two weeks backordered into Canada. I'll make do until then 
some kinda jackal fucked around with this message at 20:56 on Sep 25, 2023 |
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Sep 25, 2023 17:23
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Holy poo poo, finally
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Sep 28, 2023 02:20
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I have a bunch of network equipment that all runs on its own individual barrel jack wall wart, and I think it'd make a lot more sense to just have one DC power supply that supplies all of them (they're all either using 5V, 9V or 12V and the highest rated draw is only 1A). But is there some hidden gotcha here about connecting a bunch of things together that previously assumed they'd all have their own isolated power supplies? I guess I could get a ground loop going but I don't think network equipment really cares about those, right?
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Sep 28, 2023 15:28
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Shame Boy posted:I have a bunch of network equipment that all runs on its own individual barrel jack wall wart, and I think it'd make a lot more sense to just have one DC power supply that supplies all of them (they're all either using 5V, 9V or 12V and the highest rated draw is only 1A). But is there some hidden gotcha here about connecting a bunch of things together that previously assumed they'd all have their own isolated power supplies? I guess I could get a ground loop going but I don't think network equipment really cares about those, right? Ethernet is transformer-isolated up to like 1kV, so if that's the only thing going between these things and in/out (and you're not doing power-over-ethernet) you'll be fine.
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Sep 28, 2023 15:52
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I was trying to figure out a rechargeable battery that could last an exceptionally long time in float mode (UPS style) without replacement. On the order of at least a decade, maybe 15-20 years? Maybe solid lead Hawker Cyclons (I think now Enersys Cyclon) which are rated for 15 years. Any other ideas? It sounds like satellites for example use some exotic poo poo but that Nickel Cadmium may still be popular. Not that I would know where to source actual good quality NiCad. I feel like even if an ultracapacitor could meet my needs, I wouldn't necessarily trust any of the current manufactured materials to last 10+ years since there's really no track record.
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Sep 30, 2023 18:00
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Not just NASA, they’re used in electrical substations as well. Depending on where you are they’ll be hard to get though.
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Sep 30, 2023 19:27
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Rescue Toaster posted:I was trying to figure out a rechargeable battery that could last an exceptionally long time in float mode (UPS style) without replacement. On the order of at least a decade, maybe 15-20 years? NiCad is the battery chemistry for this. If you never ever ever go below 80% depth of discharge and have the ability to do a conditioning cycle on it once a year, they will absolutely last decades.
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Sep 30, 2023 19:45
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Rescue Toaster posted:I was trying to figure out a rechargeable battery that could last an exceptionally long time in float mode (UPS style) without replacement. On the order of at least a decade, maybe 15-20 years? Lithium Iron Phosphate (LiFePO4) is also a very good chemistry for this. I've had some for an ebike that were dischrged to 0% and left like that for 5 years and are still fine after being charged back up. A123 projected that after 15 years they'd only lose 23% capacity (but avoid A123 themselves, they had very bad QC). Other Lithium chemistries can't get away the abuse the Iron chemistries can tolerate.They're also way more stable; people on YouTube drill through them and they don't burst into flames like Li-Ion. These Valence brand are already like 10 years old, they've been used successfully in electric cars, and were the official battery for some early Segway models: https://www.ebay.com/itm/166270802879 The disadvantage is they're quite heavy, but in a UPS application it shouldn't matter.
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Sep 30, 2023 21:29
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Any thoughts on NiCad vs NiMH? When you say 'conditioning' how deep of a discharge are we talking? I wouldn't want to risk power going out while the discharge just happened to be near the bottom. Although dual batteries might even be doable if it simplified that problem enough. EDIT: Yeah my only consideration for lithium chemistries would be lifepo4. I just wasn't sure quality-wise how the smaller 18650's and 22650's fare. There isn't really room for a big giant pack. The reality is I technically need like 30 watts for 1 minute tops... not even a single watt-hour. But obviously that's a few amps in the 6-7.2v range which would maybe stress some of the nickel-based chemistries if the mAH was really small. Rescue Toaster fucked around with this message at 21:35 on Sep 30, 2023 |
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Sep 30, 2023 21:32
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NiCd and NiMH used to be the go to batteries for power tools and RC cars until lithium batteries came and ate their lunch. Sub C sized cells can deliver 10+ amps easy. However, I don't know how compatible that high amp draw is with a long lifetime for the battery itself.
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Oct 1, 2023 02:13
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My experience of nicd and nimh are both in cycle use, and occasionally in 'oops i left it to self discharge to 0%' use. Ni-Cd is a lot hardier it seems. I have a bunch of AA Ni-Cds of 20 years old that are still functional, despite the 'oops left it to self discharge' moments. Ni-MH's don't last long in this type of abusive scenario. I have no 20 year old Ni-MHs and even in my stack of 5 year old D cells (that are annoyingly expensive to replace) i have like 20% failure after about 20 cycles in 5 years. They are store brand, but made in germany afaik. Ni-Cd will eventually die if you overcharge the hell of it on a daily basis. Handheld vacuum cleaners and power tools with dumb fast chargers were notorious for that. They'll tolerate overcharging at 1/10c for quite a while, but even in that case it's best to actually stop charging when they're full. If space and topping up with water is not an issue, check out nickel-iron batteries. Those were the go-to backup solution for telephone exchanges throughout the 20th century if you needed a stack of batteries that would last for decades.
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Oct 1, 2023 08:36
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Rescue Toaster posted:Any thoughts on NiCad vs NiMH? When you say 'conditioning' how deep of a discharge are we talking? I wouldn't want to risk power going out while the discharge just happened to be near the bottom. Although dual batteries might even be doable if it simplified that problem enough. NiCad batteries are used as the primary starting battery in aircraft. They'll flow a few hundred amps for a dozen or so seconds a few times, then get recharged. The conditioning cycle is a whole process where you discharge the battery, short all the cells to remove all charge, then charge the battery back up. It can take a few hours. But if you're not going below 90% depth of discharge, then you only have to do that once a decade according to the manual I just read.
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Oct 1, 2023 15:43
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FWIW a few years ago I rebuilt a battery backed instrument supply at work, that thing was built ca. 1991 and only started having real problems in ca. 2020. That was a highly intermittent loading scenario where it was left alone for 6-12 months without charging, then charged up and used for a few days. Talked to the local battery vendor, they sold me new Ni-Cd assemblies, still going strong!
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Oct 1, 2023 18:54
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Any recommendations for a programmable load that can handle at least 400 volts? I don't need lab-grade precision, just safe and not crazy expensive. If there's something popular I can score on eBay used that would be fine too. Some of these things are like $10k used though, jeez.
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Oct 5, 2023 02:07
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Zero VGS posted:Any recommendations for a programmable load that can handle at least 400 volts? I don't need lab-grade precision, just safe and not crazy expensive. If there's something popular I can score on eBay used that would be fine too. Some of these things are like $10k used though, jeez.
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Oct 5, 2023 03:02
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Captain Cool posted:How much power? And what do you need from a programmable load that you can't get from a set of power resistors? I want to be able to discharge a couple hundred watts at least, so it won't take forever, and also be able to have the discharge stop at a certain voltage so I don't over-discharge a battery (and also so I can discharge multiple batteries to match each other). Can a programmable load do that last part? Zero VGS fucked around with this message at 04:39 on Oct 5, 2023 |
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Oct 5, 2023 03:37
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I've only worked with electronic DC loads, and I don't think they can do that, and they're still expensive. How about a simple low-voltage disconnect like this: https://www.amazon.com/dp/B07WDLFTY9/ Use the 48v version. Put one power resistor in line with the battery, a second as the load. That forms a voltage divider that will keep the disconnect from seeing a voltage higher than its max rating. Edit: nm, once that disconnects it will see the full voltage of the battery. You'd need to find or make a version that can handle a higher voltage. Captain Cool fucked around with this message at 17:43 on Oct 5, 2023 |
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Oct 5, 2023 17:34
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Zero VGS posted:I want to be able to discharge a couple hundred watts at least, so it won't take forever, and also be able to have the discharge stop at a certain voltage so I don't over-discharge a battery (and also so I can discharge multiple batteries to match each other). Can a programmable load do that last part? I have one of these at work: https://www.circuitspecialists.com/collections/dc-electronic-loads/products/itech_it8511b-plus_programmable_dc_electronic_load It has a battery mode which basically does what you want. Set it to discharge at a constant current/power until it hits a predefined voltage, and records the total amp hours or watt hours.
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Oct 6, 2023 00:34
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ANIME AKBAR posted:I have one of these at work: https://www.circuitspecialists.com/collections/dc-electronic-loads/products/itech_it8511b-plus_programmable_dc_electronic_load Oh cool, thanks! Not super expensive and 500v is plenty. Though, it says on your link IT8511B+ Interface: "RS232/USB/RS485" but I don't see USB on it anywhere. The manual says USB is only on the version that's 60 amps instead of 10 and costs $1000 more.
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Oct 6, 2023 01:23
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Without knowing anything about the product but having used a lot of lab equipment, I think odds are it's a USB serial interface that could be functionally duplicated with a 10 dollar adapter.
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Oct 6, 2023 15:59
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Holy crap, these boards are so beautiful, I sure hope they're equally functional and correctly-designed! The white added a day or two in theory, but I am pretty sure it was still like a 24-hour turnaround. My lighting gives it a slightly yellow cast, but rest assured it is absolutely pure bright white. The ENIG upped the cost but it was all so cheap anyhow, and it looks like a NASA spacesuit or something, I don't even care.  e: I can at least say that all my through-hole components fit! I probably should have left another 1-2mm between the power block and the rPi, the sd card juuuust touches the transformer. It fits, but there's zero slop. Or I could have spun that whole half 180, but then power routing was more of a hassle. Oh well, good enough! Bad Munki fucked around with this message at 22:59 on Oct 9, 2023 |
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Oct 9, 2023 22:32
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I've got a prop with lights installed in it that is running ~200 LEDs on WS2812B strip lighting from a pair of 18650 batteries in parallel. I was using one of these ESP32s as my test breadboard microcontroller to drive the lighting animations. Since this is mostly just there to run the light animations, I was hoping I could shrink it down to something a little smaller/more compact. There are things like these that are certainly smaller, but I don't even need the WiFi capabilities or anything. Do you guys have any good recommendations for something that can run on the 3.7 - 4.2V power that the 18650s deliver and has enough memory to handle LEDs properly in a small footprint?
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Oct 10, 2023 01:48
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I'm looking to buy a bunch of various LED lights to put in my car (dash, brake lights, interior light, rear lights, not headlights). I'm just gonna buy a bunch from aliexpress is the plan. Almost every single one mentions CANbus and my car doesn't have it, at least not for lights (good, I think that's dumb), but I read somewhere that if you put canbus leds in non canbus outlets they can flicker? Any truth to that? Perhaps a crosspost to AI is needed.
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Oct 10, 2023 08:02
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I ended up upgrading my DHO800 order to a DHO914 just in case I ever decide I want or need a logic analyzer in the future, AND they pushed back my 800 order a few weeks while they had some 900s coming in sooner, from what I'm told. The price difference wasn't ridiculous, though my impulse upgrade was really only facilitated by the fact that someone is cloning a DIY Rigol's logic analyzer pod for the DHO900s because the OEM one is like $500 on top of the $700-something (CDN funbucks) for the base scope which seems like a LOT for a breakout PCB connected to a bunch of leads but what do I know.
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Oct 10, 2023 16:28
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Nice monsteras!
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Oct 10, 2023 17:23
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some kinda jackal posted:I ended up upgrading my DHO800 order to a DHO914 just in case I ever decide I want or need a logic analyzer in the future, AND they pushed back my 800 order a few weeks while they had some 900s coming in sooner, from what I'm told. FWIW I sprung for the MSO version over a DSO Rigol for work, and I've use the logic analyzer stuff like... twice. Honestly the $12 cheap logic analyzer from AliExpress or Amazon works really really well and handles 95% of my stuff better, connected to a computer with good protocol analyzers. The times I've used the scope was doing some mixed signal stuff, but I probably could have hacked something together with the cheap solution too
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Oct 10, 2023 18:33
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Nah I hear you. This is definitely one of those cases where I had the spare cash and figured I'd kill two birds with one stone (availability, and a potential LA if I ever need it) without too much hassle. I predict that the 4 channels + decoder will be 100% satisfactory for my needs in perpetuity, but the probe PCB will be a fun-ish build and on the off chance I want to do a trace with more probes in 20 years I'll be all  , ignoring that the price difference would have paid for a more versatile analyzer. But yeah so when I say kill two birds with one stone I suppose I really mean "I'll get my scope sooner" and the other bird not only hasn't hatched yet, but hasn't been conceived. Impulse buy
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Oct 10, 2023 18:48
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His Divine Shadow posted:I'm looking to buy a bunch of various LED lights to put in my car (dash, brake lights, interior light, rear lights, not headlights). I'm just gonna buy a bunch from aliexpress is the plan. If you're talking replacements for incandescent lamps all "CANbus compatible" means is that the lamps are designed to draw extra current so cars that detect burned-out bulbs won't sense the LEDs as being burned out. This is also good for older cars with electromechanical turn signal flashers because the extra load is needed for those to flash and not just stick on. They shouldn't flicker any more in a car that doesn't try to detect burned-out bulbs, but thanks to low frequency PWM dimming a lot of LED bulbs are just kind of flickery anyway.
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Oct 10, 2023 19:21
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Working on a Raspberry Pi project and I want some attractive indicator lights. Having a hard time tracking down the sort of thing I'm looking for, wondering if anyone might have suggestions:
I'm planning to stuff all this inside a wooden box, so I'm aiming for a more old fashioned look, not a cold modern blue. Ideally I want to find a cheap old (broken) tube radio I can gut and repurpose.
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Oct 10, 2023 21:03
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Stack Machine posted:If you're talking replacements for incandescent lamps all "CANbus compatible" means is that the lamps are designed to draw extra current so cars that detect burned-out bulbs won't sense the LEDs as being burned out. This is also good for older cars with electromechanical turn signal flashers because the extra load is needed for those to flash and not just stick on. They shouldn't flicker any more in a car that doesn't try to detect burned-out bulbs, but thanks to low frequency PWM dimming a lot of LED bulbs are just kind of flickery anyway. That sounds good, I bought a bunch of them as well as rear indicators and brake lights and so on. This car is so old (1990) it doesn't have any of that fancy stuff like PWM dimming. Unrelated question, I asked it before but the project never took off and I am looking to reboot it. I have an old 4A variac from east germany that I want to build an enclosure for. I need to varnish the windings in places but all my local electronics store carries is an expensive spray can that's 2x the cost of a regular spray can of lacquer. Is there any reason for me to buy the more expensive stuff? Is lacquer what I want, or should I go for polyurethane? I can get small jars of 1k polyurethane at work that we use on wood so that'd be one cheap and easy way. 
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Oct 11, 2023 07:19
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