hybridfree/eevblog-posts huggingface dataset:
What do with a bunch of TPA3122? - Page 1
Forum section: electronics / projects

author: resistor
author_rank: Regular Contributor
timestamp: December 22, 2014, 09:46:04 pm
content: So, I ordered a couple of TPA3122 Class-D amplifier ICs, but somehow managed to end up with two *tubes* of them! Is there anything uses I can do with a whole bunch of these things?

author: dannyf
author_rank: Super Contributor
timestamp: December 22, 2014, 10:14:30 pm
content: Each channel is a self-oscillating half bridge.That may broaden your imagination a little.

author: moffy
author_rank: Super Contributor
timestamp: December 22, 2014, 10:55:07 pm
content: I once order a set of screws from RS Components and started receiving boxes and boxes of screws instead of just a single set. The operator had typed the Part Number into the quantity field. We still had several hundred thousand on back order!Sorry doesn't help you, but your predicament reminded me of the incident.

author: wraper
author_rank: Unknown
timestamp: December 22, 2014, 11:57:38 pm
content: I guess it is better to sell them here/on ebay or give them away at postage cost rather than figure out why you would want to keep them.

author: Zero999
author_rank: Super Contributor
timestamp: December 23, 2014, 01:42:03 am
content: Quote from: resistor on December 22, 2014, 09:46:04 pmContact thge supplier and offer to return the ones you didn't order, if they pay the postage?

author: calexanian
author_rank: Super Contributor
timestamp: December 23, 2014, 05:35:25 am
content: I forgot all about those chips.. Build a bunch of little powered speakers for people. With all the 50 watt 24 volt brick power supplies out there dirt cheap one of those chips, a little box, and a handful of components makes the perfect little amplifier. Use an old pair of bookshelf speakers and you are in business! Also there are many little Bluetooth receiver dev kits out there. That would be a great combination and for a very small cost in mostly used components you would have a Bluetooth speaker system that rivals the overpriced junk at the stores I have been seeing lately.
What do you think about my pitch deck? (sensor modules) - Page 1
Forum section: electronics / projects

author: Georgy.Moshkin
author_rank: Frequent Contributor
timestamp: September 17, 2023, 11:18:23 am
content: Here is my presentation. Is it good or bad?It's about three modules: gesture sensor, radar sensor and camera sensor for hobby and semi-professional market. I have some demo videos also.
What do you think of the Framework 16 expansion bay? - Page 1
Forum section: electronics / projects

author: LoveLaika
author_rank: Frequent Contributor
timestamp: April 25, 2023, 05:41:15 pm
content: I asked a more general question about this in another forum, but I wanted to get some opinions on the potential of the expansion bay. With the new Framework 16 Laptop coming, I was wondering what you thought of the expansion bay.In general, the idea behind the laptop is cool, and I like the support that's already been given to it in theirGithub repos. Plus, I have to admit that Linus's enthusiasm for the new laptop is contagious. It does seem pretty cool how he was able to add the modular inputs. At least he's having fun with it.With the expansion bay that was mentioned, what do you think could be designed with that space? It seems pretty big, but it seems like there's a lot of potential for engineers. Linus mentioned that you could design something like an oscilloscope in that bay, but that's out of my depth whether it could be done or not. Still, I thought the idea was pretty cool. The idea of a dedicated graphics unit seems cool too.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 26, 2023, 01:44:59 am
content: It took me some time to recognize that guy with the beard.I've been boycotting him for a few years now because he throws in too many and too obnoxious advertisements.

author: LoveLaika
author_rank: Frequent Contributor
timestamp: April 26, 2023, 01:18:01 pm
content: I suppose that's fair. Still, any thoughts on the subject matter?
What do you use for ESD protection today? - Page 1
Forum section: electronics / projects

author: Gibson486
author_rank: Frequent Contributor
timestamp: June 27, 2018, 02:07:54 am
content: Do you use gold old one diode to VDD and one to GND? Do you use a TVS? A zener? Do you use a chip that combines multiple different types?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 27, 2018, 02:49:23 am
content: Yes.There is no single ESD solution, because there are many situations and requirements. Clamp diodes are fine for logic signals, but bad for:- Inputs with wide voltage range, e.g. analog, RS-422, CAN- Where the signal must not be loaded by a deenergized supply (various bussed and low-power systems)- Where the clamp voltage is different from the supply voltage (another way to say the above, really)- Low leakage applications (give or take diode type and requirement -- schottky are fine for logic, but often unsuitable just for general analog signals; junction diodes are unsuitable for very low leakage analog signals)Tim
What does 2xMOPP really mean - Page 1
Forum section: electronics / projects

author: foxr
author_rank: Newbie
timestamp: October 16, 2023, 02:41:13 pm
content: Hi there,I am a student and I am designing a medical device that has a type CF applied part.I know the specifications that the applied part must comply (4kV of insulation, 8mm of creepage, <10μA patient leakage current, 2xMOPP), but I don't understand what 2xMOPP means in practice. I know the definition is two means is patient protection and that it requires double insulation or reinforced insulation, but I don't know how to design a power supply that complies with that.Does double insulaiton just mean I have to insulate the part twice? So can I use two isolated DC-DC converters (that don't provide 2xMOPP) that have 4kV of insulation in series?Sorry if I seem a bit lost, but reading IEC 60601-1 isn't answering my questions.Thanks in advance!

author: Vovk_Z
author_rank: Super Contributor
timestamp: October 16, 2023, 05:27:24 pm
content: You don't have to design a medical-grade power supply if you are a student.And, reading about2xMOPPsays 2xMOPP is not double insulation. It means double insulation and onemore different safetymeans.
What does BC mean on a PCB terminal? - Page 1
Forum section: electronics / projects

author: robzy
author_rank: Regular Contributor
timestamp: July 17, 2024, 03:02:12 am
content: I pulled apart one of these:https://www.jaycar.com.au/compact-switchmode-laboratory-power-supply/p/MP3800And I can't quite remember how to reconnect the 2 output terminals.The PCB has three terminals in the same place: +, GND, and BC GND -.Coincidentally this video by Clough 42 shows a circuitboard that also has a "BC-" terminal:What is the BC terminal for? What does it stand for?

author: DTJ
author_rank: Super Contributor
timestamp: July 17, 2024, 01:47:14 pm
content: Flip the PCB over, are the BC-GND and the other GROUND connected and connected by the same weight track?If so it may not matter which one you connect the output ground to.

author: Harry_22
author_rank: Frequent Contributor
timestamp: July 17, 2024, 08:34:45 pm
content: Bare Copper ?

author: thm_w
author_rank: Super Contributor
timestamp: July 18, 2024, 12:08:16 am
content: The Clough video has BC+ (red) and BC- (black).Its likely hinted in the manual:https://kb-controls.com/content/product_pdf/KBAC%20Manual.pdfI don't know where they go off to, something internal to the drive.Anyway I doubt its related to the Jaycar PSU at all. BC there might be bare case, bottom case, or something.

author: robzy
author_rank: Regular Contributor
timestamp: July 18, 2024, 01:41:33 am
content: Quote from: DTJ on July 17, 2024, 01:47:14 pmAnnoyingly - they are not directly connected.Electrically they are connected - according to my multimeter - but they come from different parts of the circuit.There's spare PCB between the two terminals, so they could've been directly connected if desired.I want to say "if they appear electrically connected then it won't make a difference" - but why would they go to all the trouble of routing them in from different places?

author: Jonathon_Doran
author_rank: Regular Contributor
timestamp: July 18, 2024, 02:21:36 am
content: Battery connection?

author: floobydust
author_rank: Super Contributor
timestamp: July 18, 2024, 05:02:40 am
content: I think "BC GND-" means Bus Capacitor(-) for the VFD motor drive PCB pic shown Clough 42. That is for the primary HV bus, after the mains bridge rectifier.What it means for the Jaycar lab power supply though must be different... the pic shows it right near the LV secondary terminals which would be very dangerous spacings if "BC GND-" goes to the primary MOSFET source after a sense resistor. You'd have to follow it back the PCB trace. It could be for EMI with C101,102,103 connecting the two grounds.

author: DTJ
author_rank: Super Contributor
timestamp: July 18, 2024, 12:15:04 pm
content: Quote from: robzy on July 18, 2024, 01:41:33 amI've no real reason to say this but I wonder if there is current sensing in the ground return circuit and the two ground side lugs straddle the current shunt.

author: robzy
author_rank: Regular Contributor
timestamp: July 18, 2024, 01:01:05 pm
content: Quote from: DTJ on July 18, 2024, 12:15:04 pmThat's a really interesting theory!
What does HSG stand for? - Page 1
Forum section: electronics / projects

author: Gibson486
author_rank: Frequent Contributor
timestamp: September 13, 2019, 02:38:15 pm
content: Probably a dumb question....I am specing out Molex cable assemblies. I keep seeing the digikey description mention HSG. What does HSG stand for?

author: TimNJ
author_rank: Super Contributor
timestamp: September 13, 2019, 02:43:46 pm
content: Housing?

author: Gibson486
author_rank: Frequent Contributor
timestamp: September 13, 2019, 04:05:18 pm
content: LOL....that would make sense....
What does "Output Noise Voltage" tell me about SPICE models? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: June 11, 2018, 08:31:15 am
content: From the data sheet for the 2SK1578 JFET:http://www.onsemi.com/pub/Collateral/2SK1578-D.PDF"Output Noise Voltage VNO VIN=0V, A curve -110dB"I'm not sure what this tells me about the JFET in question.I'll guess the "A curve" is something like an op-amp open-loop gain curve, and the "-110dB" means the "noise gain" is 110db down WRT the open-loop gain. But I'm unsure how the JFET is rigged up in that case.It looks like "A Curve" will be an "IHF-A curve", which is some frequency-weighted response curve. The single figure quoted suggests something like noise integrated over a fixed fmin, fmax and under that curve.IHF = Institute of High FidelityPresumably the noise measurement includes all noise eg flicker, shot, Johnson?Can I derive a SPICE "Flicker noise coefficient" (Kf) from this?How about "Flicker noise exponent" (Af)?
what does "SWP" stand for in this power supply datasheet - Page 1
Forum section: electronics / projects

author: nexus
author_rank: Regular Contributor
timestamp: June 18, 2023, 05:37:39 pm
content: Hi all,I am retrofitting a new PSU to replace these old Aztec LPS122s in some test equipment. 2 out of 3 boxes have bad power supplies, so these don't seem to be very reliable.Anyway, on the LPS122 datasheet, there is one control signal on connector SK3 pin 7 that is called "SWP". I cannot find an explanation anywhere for what "SWP" stands for or what its function is.https://www.mouser.com/datasheet/2/633/artesyn%20embedded%20technologies_lps120-1216229.pdfAny ideas?

author: nexus
author_rank: Regular Contributor
timestamp: June 18, 2023, 05:42:00 pm
content: Nevermind, found the answer here:https://www.express-technology.com/getsheet.php?id=2153649"Single Wire Parallel"

author: RayMJr
author_rank: Newbie
timestamp: March 20, 2025, 05:01:34 pm
content: I have 3 questions for you:Was this piece of gear made by Tektronics?What is meant by "single wire parallel"? I am puzzled about what that function is.Did you recover the piece of gear? I am working on a WFM8200 with the same issue. (No longer supported, no parts available)Ray
What does this circuit do? - Page 1
Forum section: electronics / projects

author: MasterBuilder
author_rank: Regular Contributor
timestamp: February 02, 2015, 07:31:06 pm
content: I need some help working out what the attached circuit is doing.I believe it to be an isolation test device.I am only concerned with the bottom half of the circuit.I think the DUT is connected at J2. If it is, C6 would block DC. This Does this look like an ESR test circuit?Is the bottom left an oscillator?VR1 looks important.

author: moffy
author_rank: Super Contributor
timestamp: February 03, 2015, 03:43:35 am
content: It looks like an ESR measurement for electrolytic capacitors. From the comments on the diagram.

author: MasterBuilder
author_rank: Regular Contributor
timestamp: February 03, 2015, 09:08:53 am
content: Thanks Moffy. But I should have added the comments are all mine.

author: moffy
author_rank: Super Contributor
timestamp: February 03, 2015, 11:33:42 pm
content: Ok I take it back, it has nothing to do with ESR. It measures the capacitive coupling to whatever is attached at J2 and when the delay is just right Q1 and /Q2 are high, indicating a pass. Pencil Point Height?

author: MasterBuilder
author_rank: Regular Contributor
timestamp: February 04, 2015, 12:15:49 am
content: Thanks moffy, The device for testing here is a medical electrode, with a coating for isolation. It makes sense that this would test capacitive coupling.Any ideas whats the purpose of U3A? The clock pin is connected to ground, which I think means the CD4013 stays in one state.I think the DUT may be connected between J2 pin 2 and U3A pin 2?What determines the delay, VR1 in series with R4 and C6?

author: moffy
author_rank: Super Contributor
timestamp: February 04, 2015, 01:55:59 am
content: What U3A does I'm not sure, you would be best building it to see, most direct is often the simplest.You have 3 delays:1. R7/C42. VR1/R4/C8(parasitic capacitance) + C3/R63. R5/C2It is basically a race condition as to what the logic outputs of the FF's will be.

author: Stonent
author_rank: Super Contributor
timestamp: February 04, 2015, 03:04:23 am
content: John Carr would know.
What does this mean. - Page 1
Forum section: electronics / projects

author: thedoc298
author_rank: Contributor
timestamp: October 04, 2019, 11:29:01 pm
content: This is on the tag of a distribution transformer. Does anyone know what the number 12470Y mean. Thanks

author: helius
author_rank: Super Contributor
timestamp: October 04, 2019, 11:43:32 pm
content: 12470 is the voltage across phases, and Y means it is a wye-connected primary. The primary voltage betwen each phase and the neutral (star) point is 7200. Seehttp://en.wikipedia.org/wiki/Three-phaseandhttp://en.wikipedia.org/wiki/Delta-wye_transformerfor more details.

author: ataradov
author_rank: Super Contributor
timestamp: October 04, 2019, 11:44:01 pm
content: 12470V is phase to phase voltage. 7200V is the phase to neutral voltage.

author: thedoc298
author_rank: Contributor
timestamp: October 04, 2019, 11:46:38 pm
content: Thank you both, knew it was 7200 but did not know the other stuff. Still learning.
What does Vf in li-ion battery mean (Chinese Imitation Batteries) - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: September 04, 2021, 11:25:23 am
content: i have encountered acordless tool that has weird markingson itI dont intend on buying this tool but i could not figure out what this Vf rating mean, I know this just some marketing crap but it muust have some bearing on something. I just could not get it of my mind.Could not find a definitive answer, Any ideas?

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 04, 2021, 01:55:56 pm
content: Just a name for one of their "standards", they're free to make up whatever name they want. Also, if it's not already obvious, that's definitely not a 22.8Ah battery, just take a look at the size of a Ryobi 9Ah to get an idea of how big it really is. (The picture looks like 4-5Ah at best.)

author: Terry Bites
author_rank: Super Contributor
timestamp: September 04, 2021, 05:02:19 pm
content: Violently flammable?

author: mikerj
author_rank: Super Contributor
timestamp: September 04, 2021, 07:14:50 pm
content: Surely it's just a model number?

author: Miti
author_rank: Super Contributor
timestamp: September 06, 2021, 02:51:11 pm
content: Quote from: Terry Bites on September 04, 2021, 05:02:19 pm

author: thm_w
author_rank: Super Contributor
timestamp: September 07, 2021, 10:09:13 pm
content: Big clive had a 24V battery pack charger that said 24V-98Vf. But it was just 24V inside.So that doesn't really add up with the 588 number here at all.https://www.walmart.ca/en/ip/98VF-320NM-12000mAh-Cordless-Electric-Impact-Wrench-Drill-Screwdriver-110-240V-with-LED-Light-One-Battery/3TU3YIZMBBUPHere is one thats 98Vf and 12000H (mAh). The 12,000 at least could be viable, 2400mAh * 5 = 12000.98 makes no sense at all though... peak 4.2V per cell * 5 = 21V

author: abdulbadii
author_rank: Frequent Contributor
timestamp: November 27, 2022, 11:58:19 pm
content: Vfvoltage of filament of a vacuum tube ?

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 28, 2022, 02:04:52 am
content: Quote from: Miti on September 06, 2021, 02:51:11 pmincidentally... when the look and price is good... look at the "Very feedback"... to see its "Very fake"https://www.joom.com/en/products/5ff2b4512acb410106ce4067

author: elecdonia
author_rank: Frequent Contributor
timestamp: December 02, 2022, 02:03:59 am
content: Is that lump of partially burned plastic the remains of that TA2110 charger?Or is it what’s left of an exploded battery pack that you tried to charge with that charger?Or maybe a combination of both items?-EB
What effective number of bits to expect from a cheap PC ADC? - Page 1
Forum section: electronics / projects

author: erikka
author_rank: Regular Contributor
timestamp: March 31, 2023, 05:39:37 pm
content: For a project I'm running a cheap audio ADC used in PC applications on 192kHz and I seem to get only 12 usable bits.Is this to be expected or is there probably some input noise to address?

author: Berni
author_rank: Super Contributor
timestamp: March 31, 2023, 05:43:20 pm
content: Yep the integrated audio in some motherboards has been famously bad. All sorts of digital noise getting into it from other stuff on the motherboard.USB sound cards tend to be a lot better, even cheep ones.

author: RoGeorge
author_rank: Super Contributor
timestamp: March 31, 2023, 05:59:46 pm
content: - You mean a 16bits/192kHz, or 24/192? What CODEC or ADC/soundchip do you use (to lookup the datasheet)?- Is it on a custom board, or is it in the soundcard of a PC? Many CODEC chips have a lot of settings and internal DSPs that might alter the performance when misconfigured.- Do you really need the 192kHz sampling? Often this does not increase the bandwidth (it is still limited by internal DSP filters). You may get more bits and lower noise floor when sampling at 44kHz.

author: coppice
author_rank: Super Contributor
timestamp: March 31, 2023, 06:06:27 pm
content: 20 years ago the quality of built in audio on motherboards was awful. These days it is generally pretty good. You should get a lot more than 12 bits. In fact its normally worth using 24 bit mode, rather tan 16 bit mode, as they are capable of more than 16 bits. If you don't need the full bandwidth of 192 samples per second, you can do some filtering to get the noise down. The big problem for general purpose use is these are audio converters. They are usually AC coupled, and they usually have a DC offset component in their output despite that AC coupling. Depending on your application that may make them entirely useless or a terrific fit.

author: jonpaul
author_rank: Super Contributor
timestamp: March 31, 2023, 07:15:03 pm
content: For 16 bits LSB, check divide max output by 2 exp 16At 24 bits, you will be surprised how low,the LSB is.check for power supply noise on ADC, DAC ICS,measure CM, DM noiseUse appropriate amplifier, lowpass filtering and probe technique.j
What encoding does this look like? - Page 1
Forum section: electronics / projects

author: goldserve
author_rank: Contributor
timestamp: December 30, 2020, 11:36:58 pm
content: Does this look like manchester encoding and what does it decode to?

author: ve7xen
author_rank: Super Contributor
timestamp: December 31, 2020, 12:35:14 am
content: Definitely could be. Could also just be NRZ, though if it has no periods that appear to be at least 3 bits long, like this capture (the last high period is probably long enough but that might just be an artifact), it's probably manchester.Decoding manchester is simple. If the full period contains a transition in the middle, it is one state, and if it doesn't, it's the other state. There will always be a transition at the beginning of each period. If we take the inclusion of a transition to be '1', then this decodes to 1100 0111 1010 0000.

author: goldserve
author_rank: Contributor
timestamp: December 31, 2020, 08:42:47 am
content: Is what you are describing biphase? For Manchester encoding, doesn’t low to high and high to low mean 1 and 0 respectively? Thanks!

author: Nusa
author_rank: Super Contributor
timestamp: December 31, 2020, 12:36:18 pm
content: Quote from: goldserve on December 31, 2020, 08:42:47 amYes, or the inverse of that, depending on which Manchester convention you're following.What ve7xen described is a differential Manchester encoding. It also demands that there be at least one transition every period (only the middle counts for data purposes), so the tail end of that sample isn't data.That's assuming it's a Manchester encoding at all. It could just as easily be a serial protocol.

author: mikerj
author_rank: Super Contributor
timestamp: December 31, 2020, 12:47:24 pm
content: Quote from: ve7xen on December 31, 2020, 12:35:14 amManchester encoding always has a transition in the middle of the bit period, the polarity of the transition holds the bit value. For the IEE802.3 standard a positive transition is a 1, a negative transition is a zero:

author: m k
author_rank: Super Contributor
timestamp: December 31, 2020, 05:56:33 pm
content: If short is one and long is two bits then different can be one and same another and ve7xen's guess can still hold.Then if end is two more of what was the last the result is eighter four or three bits of same and end is also covered.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: January 04, 2021, 12:00:07 pm
content: The last pulse seems to be too wide for Manchester, but it could be an "end of message" token.
What FCC certification test that I need to pass for project that I am working on - Page 1
Forum section: electronics / projects

author: mgwalker95
author_rank: Contributor
timestamp: April 24, 2024, 02:01:00 am
content: Hi,I am working on a wireless charger that is also a wireless receiver(https://www.reddit.com/r/hwstartups/comments/1cbdw74/comment/l0ykgl9/), but I am not sure what FCC testing that I need to do to sell in the US. What where should I be looking? Should I contract it out? Can one of point me in the right direction? Also any feedback on the project is much appreciated!

author: Smokey
author_rank: Super Contributor
timestamp: April 24, 2024, 03:46:35 am
content: Nice looking product. Did you have that case custom made?Based on this random guy on the internet:https://www.freepower.io/blog/the-challenges-of-designing-a-free-position-multi-device-system... wireless chargers are considered to be "intentional radiators" by the FCC, so you will need Part15 ClassC certs.Every device is different but for reference, I did a BLE wearable last year. I passed on the first round and it ended up taking 2 days of test time and costing about $6200. Failing would have required a redesign and retest at about the same cost.I'm no expert, but if you are starting from scratch it's a pretty steep learning curve. You can do some pre-compliance testing in-house but it requires some decent gear to have any real confidence in the measurements. I was sort of surprised there weren't more companies offering pre-compliance services. Hopefully you are in an area with at least some test labs locally.

author: Smokey
author_rank: Super Contributor
timestamp: April 24, 2024, 03:50:40 am
content: Ha! I just saw that it looks like you posted the same thing to as many sub-reddits as you could think of.

author: mgwalker95
author_rank: Contributor
timestamp: April 24, 2024, 05:45:43 pm
content: Thank you, I designed the custom case my self and had it CNCed at a prototype shop in china.Thank you for pointing me in the right direction! I will look into Part 15 Class C certs!I dont have any of the equipment, but I will look and see if I can find anyone who does pre-compliance.

author: mgwalker95
author_rank: Contributor
timestamp: April 24, 2024, 05:48:06 pm
content: I tried to post it in subreddits that I thought were relevant or ones where they would think its interesting.
What female connector mates with this? - Page 1
Forum section: electronics / projects

author: Chad1
author_rank: Contributor
timestamp: December 04, 2015, 07:27:20 am
content: Hey everyone,I'm working on a project that will use the switch in the below link. Can anyone easily identify a female connector that will mate with the connector on the switch? I know I can take some measurements and find a solution once I get the switch in the mail (assuming it's not a proprietary connector), but I thought I'd ask here first in case any connector experts out there can easily identify what I'd need.http://www.amazon.in/Refrigerator-Momentary-Light-Switch-250VAC/dp/B00NQS59AOMy preference is to find a compatible female connector to avoid soldering wire onto the switch terminals. I just want to eliminate the risk of melting/damaging anything inside the switch, while also making it easier to take apart.Thanks!

author: amyk
author_rank: Super Contributor
timestamp: December 04, 2015, 09:20:35 am
content: $1300+? That is one expensive switch...I can see why you really don't want to damage it.I can't see the terminals on that one in particular, but those types of switches usually take standard spade terminals.

author: senso
author_rank: Frequent Contributor
timestamp: December 04, 2015, 10:43:24 am
content: Not dollars, but Indian Rupee, about 20$ for that switch, still expensive, by the photo that looks like 0.1" header pins.

author: Chad1
author_rank: Contributor
timestamp: December 05, 2015, 03:39:32 am
content: I was hoping it would be compatible with a standard 0.1" header. Thanks for the thoughts!

author: matseng
author_rank: Frequent Contributor
timestamp: December 05, 2015, 04:18:33 am
content: $5 at Newegghttp://www.newegg.com/Product/Product.aspx?Item=0UW-002A-003S7or $6 at Sears .The connectors looks like regular spade terminals to me, so maybe these will be a decent match?
What flat cable and where to find it for an I-PEX connector? - Page 1
Forum section: electronics / projects

author: nuno
author_rank: Frequent Contributor
timestamp: August 02, 2017, 12:41:22 pm
content: Hello All,I need to make some cables with 25pin I-PEX micro coax (https://www.i-pex.com/Products/detail/83#!) plugs at the ends, but don't know what flat cable to use nor where to get it. The cables will transport HDMI over some 10 - 20cm (4 - 8 inches) and it has to be flat cable. I've seen an example cable and the flat cable used looks like individual thin, insulated wires laminated between 2 clear plastic sheets, but I can't find them or I don't know the words to look for it.Any pointers are appreciated...Thanks
What flux is used in solder paste? Or how to salvage pasted boards that hardened - Page 1
Forum section: electronics / projects

author: Corporate666
author_rank: Unknown
timestamp: October 22, 2014, 11:01:37 pm
content: We stencil, place and reflow our own boards in-house. Occasionally something happens and we'll have some boards that are pasted or partially placed that, for whatever reason, aren't reflowed. Could be the P&P ran out of a needed part half way through a board, or reflow oven was down, or whatever.Over time, the solder paste hardens to an something like concrete. I've tried using off-the-shelf flux to apply it to the board and thin the hardened paste, but it doesn't seem to work too well.Any ideas on what I could do to the boards to make them usable again? I'm guessing it is just the solvent component of the flux that evaporates, so maybe soaking in IPA or something might help? Or soaking in some sort of thin (or thinned with IPA) flux? Or perhaps some kind of appropriate flux that could just be brushed or sprayed onto the boards before reflowing them?

author: EvilGeniusSkis
author_rank: Regular Contributor
timestamp: November 24, 2014, 10:34:41 pm
content: look up the MSDS for the solder paste, it will have the list of what is in the paste, from there you can figure out what solvent they are using, use that. If you had stated what solder paste you used I could be of more help

author: ovnr
author_rank: Frequent Contributor
timestamp: November 24, 2014, 11:20:20 pm
content: Do you want to clean the boards completely to re-use them, only partially to place the missing components, or just reflow everything placed on them already?I've found that most dried solder pastes re-liquify when heated to 50-150 degrees C. Then you can just wipe it off while hot. Alternatively, even if it is completely dried, you may very well be able to successfully reflow the components. There's still plenty of flux left, just no solvents.
What glue/adhesive use for Sendust/Kool Mu E core assembly ? - Page 1
Forum section: electronics / projects

author: Miyuki
author_rank: Frequent Contributor
timestamp: January 14, 2019, 11:17:40 am
content: Hi folks,do you have any recommended glue for bonding E cores made from Sendust together and also for mounting core to PCB ?

author: coppercone2
author_rank: Super Contributor
timestamp: January 14, 2019, 11:34:17 am
content: thin superglue or manufacturers recommendation

author: Miyuki
author_rank: Frequent Contributor
timestamp: January 16, 2019, 12:04:18 pm
content: So I have reply from manufacturer, if you need to glue this type of material:This powder type material cannot be glued by thin superglue, but can be used thick rubber filled superglue like Loctite 410, Cyberbond 2241Or use two component epoxy

author: jbb
author_rank: Super Contributor
timestamp: January 16, 2019, 06:16:16 pm
content: I suggest you check the temperature rating on the glues too - superglue may come unstuck...

author: gka_0509
author_rank: Newbie
timestamp: January 21, 2019, 01:39:17 pm
content: "Resinlab EP950G is a one part epoxy adhesive that is recommended for use on Powder Core materials. This adhesive has good strength at room temperature and retains strength at high temperature."https://www.mag-inc.com/Products/Powder-Cores/Learn-More-about-Powder-Cores

author: coppercone2
author_rank: Super Contributor
timestamp: January 21, 2019, 01:58:15 pm
content: why wont thin superglue work? I thought it would give better thermal contact

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 21, 2019, 02:51:29 pm
content: I remember asking that same question many years ago.If my memory serves me well, dust cores are porous, and superglue does not properly fill all the voids.

author: Bud
author_rank: Super Contributor
timestamp: January 21, 2019, 03:16:26 pm
content: I have not seen anything that could not be fixed with a 2-component epoxy tube out of a dollar store.

author: coppercone2
author_rank: Super Contributor
timestamp: January 21, 2019, 05:37:44 pm
content: Quote from: schmitt trigger on January 21, 2019, 02:51:29 pmDoes it like keep wicking into the core? Maybe it penetrates and the thermal cycling stressed it because of dissimilar tempco of the two materials. Might make signal applications suffer?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2019, 11:32:57 pm
content: Superglue may be too brittle or sensitive to temperature.Transformer varnish is also an option, which helps with the windings as well (preferably vacuum impregnated).Tim
What glue/bonder is used in paper speaker cone manufacture? - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: July 25, 2022, 07:43:20 am
content: I read people say that you can use RTV sillicone, PVC rubber cement, PVA glue, etc to repair cones. but what is actually used to make the paper pulp stiff in the cone structure?and was that different in the 50s? I read that back in the old days, nitro-celloluse adheasives were used instead of poliurethane as is nowadays. I asume those are for glueing the cone to the basket and voice coil, not the cone itself.

author: Gyro
author_rank: Super Contributor
timestamp: July 25, 2022, 08:40:13 am
content: QuoteThe interlocking of the pulp fibres and the cone shape itself - the same as is used to hold a sheet of paper together.It you're talking about repairing a tear the cone itself, then PVA with maybe a paper reinforcing patch is as strong as anything.

author: jpanhalt
author_rank: Super Contributor
timestamp: July 25, 2022, 11:02:23 am
content: Going back to the 50's and before, nitrocellulose dope/lacquer was frequently used on paper and fabric. It can also be used as an adhesive. Today it is probably best known as "nitrate" dope (e.g., Randolph nitrate dope) or guitar lacquer (new to me). See:https://www.stewmac.comIt was used as the first few coats for fabric-covered airplanes (cotten, linen, silk). It remains flexible in contrast to more modern finishes. It dries fully and causes slight shrinkage (i.e., tauntening) of the fabric. I would not recommend butyrate dope, which is more common today for top coats. Polyurethanes tend to get much harder and on fabric will crack unless there are additives to make them flexible.

author: SeanB
author_rank: Super Contributor
timestamp: July 25, 2022, 12:26:50 pm
content: That is paper pulp, blended with some fine clay, and with carbon black added as a dye to it. You are dipping in a mesh form, and allowing the fibres to settle on it, and then allowing it to drain off water, leaving the matrix of fibres and clay behind. Then it is going to be pressed into shape using a heated former to dry it and make it rigid. Likely the slurry contains as well vinyl acetate, which will add rigidity to the finished cone, and also keep it from cracking.
What happened here ? Oscillators missing a part - Page 1
Forum section: electronics / projects

author: Koen
author_rank: Frequent Contributor
timestamp: March 20, 2017, 12:38:24 am
content: Hello,I took a small gamble the other day by ordering a few major-brand oscillators from a chinese supplier (top) rather than Digikey (bottom). Instead of complete oscillators, I received shields void of the main component (what is it ?).Any idea what happened here ? Did someone sell an incomplete and to-be-trashed reel to the distributor ? Was it sold to an assembler who discovered it and later sold it to someone else ? If so, how did it pass factory QC ?The shield is correct, markings are correct, pads are correct, it is impossible to discover without inspecting one out of the reel.Somewhat related question : are the matte black blobs which are different on each oscillator's shiny black component some factory trimming ?I had to order some other components (which major distributors hardly sell) from this supplier and out of the 10 different references, only this one is wrong.Thank you,Koen
What happened to Wentai? - Page 1
Forum section: electronics / projects

author: Rasterist
author_rank: Contributor
timestamp: March 25, 2023, 07:43:34 pm
content: I have some of their SMD storage boxes and would like to buy some more, but I can't find the boxes or company anywhere. I originally bought mine from a place called 5th Postulate, but they're out of business. Can anyone point me to some? Thanks.
What happens after saturation current is reached in inductor and how to simulate - Page 1
Forum section: electronics / projects

author: Dmeads
author_rank: Regular Contributor
timestamp: October 30, 2019, 02:38:28 am
content: Hi all! Messing around with some boost converters.The Physical inductor I am looking at has a saturation current of 72A, but in my LTspice simulation, the current spikes to almost 160A before reaching SS.Wondering what will happen in a physical circuit if the saturation current is greatly exceeded?how can i simulate this?thanks!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 30, 2019, 05:14:40 am
content: More current, yeah. Are your aluminum caps modeled with correct ESR?Saturation can be simulated with a nonlinear inductor. There's a built-in or library item in LTspice, which I don't know how to use offhand but look it up, it's all documented. Personally, I use a core model from Meares and Hymowitz:Code:* Saturable Core Model, copied from:* _SPICE Models For Power Electronics_, Meares and Hymowitz.*.SUBCKT INDSAT 1 2 PARAMS: VSEC=1e-4 LMAG=1e-5 LSAT=1e-7 FEDDY=1e6F1 1 2 VM1 1G2 2 3 1 2 1E1 4 2 3 2 1VM1 4 5 0RX 3 2 1E12CB 3 2 {VSEC/500} IC=0RB 5 2 {LMAG*500/VSEC}RS 5 6 {LSAT*500/VSEC}VP 7 2 250VN 2 8 250D1 6 7 DCLAMPD2 8 6 DCLAMP.MODEL DCLAMP D(CJO={3*VSEC/(6.28*FEDDY*500*LMAG)} VJ=25).ENDSTreat it as an inductor, and couple other inductors to it (e.g. with ideal transformers plus explicit leakage inductances). LMAG is the low-bias inductance, LSAT is the saturated inductance (so LMAG/LSAT ~= mu_r), FEDDY is the eddy current cutoff frequency (yes, this models losses too(!); set this to approximately the rolloff frequency for the core material of interest), and VSEC is the flux at saturation, approximately equivalent to N*Ae*Bsat for a real core.Tim

author: Dmeads
author_rank: Regular Contributor
timestamp: October 30, 2019, 05:06:22 pm
content: yea caps have correct ESR. Thanks. I will check this out. I might try a two stage boost and see what that can do also
What happens if you put a to high input voltage on dc/dc - Page 1
Forum section: electronics / projects

author: Spikee
author_rank: Frequent Contributor
timestamp: February 25, 2016, 10:55:23 pm
content: So somebody put 7.4 VDC on my wireless circuit that uses the tps62740 which has a absolute maximum input of 6VDC.Since this circuit is at the other side of the earth at the moment, does anybody know what happens when a too high of aninput voltage is brought to such switcher ic?Buffer caps were also rated 6V3 maxDoes the dc dc just die and keep the output at zero or or does the VIN goto VOUT and basically everything dies?http://www.ti.com/lit/ds/symlink/tps62740.pdfThanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 26, 2016, 12:37:08 am
content: It looks to be a CMOS device, so it's probably like a 74LVC process (5-6V abs. max.), and goes into breakdown around 7-10V.It's probably using the same process throughout, so anything supplied by VCC and GND (like a logic inverter stage, or the output switching stage; but not a NAND or analog stage, with devices in series) will break down at about the same voltage. Most of the breakdown current will likely flow in the output switching stage (because it's biggest), which means it'll have a hard time switching when one transistor or the other is breaking down.But there are further effects, like charge injection. Breakdown around small-signal circuitry (analog parts, control logic) can cause bias currents, which can cause offset and drift, malfunction, flipped states, and total latchup.What happens is entirely contingent on: what the actual device's breakdown is, relative to the applied voltage; and how much current was delivered in the process.You're only guaranteed 6V, so breakdown could be 6.01V and they'd still be fine. Or it might have a reasonable overhead, like 8 or 10V. But who knows? And, it will vary from part to part.So, if they had low breakdown and unlimited current was applied, they're toast. Ashes. If they had high breakdown, they might simply continue operating as if nothing is wrong. If the breakdown was low, but current was limited, they might've done spooky things (like flipped states and wrong and noisy voltages and stuff), and may suffer damage (anything from thermal overheating, to accelerated electromigration I suppose). Anything inbetween is possible.If you require assurance that they are okay, your only option is to send replacements.Tim
What happens to a TL431 with disconnected cathode? - Page 1
Forum section: electronics / projects

author: rr100
author_rank: Frequent Contributor
timestamp: September 21, 2015, 09:06:01 am
content: simple question - it looks like the Ref is sinking some current if going about certain voltage. Looking at the detailed schematic from datasheet it looks there's a path for the current to go from Ref to Anode via some resistor(s) in KOhm range and transistor junctions. This is it? Any idea how much voltage can take and/or current can sink?

author: ralphd
author_rank: Frequent Contributor
timestamp: September 21, 2015, 09:53:20 am
content: At around 3.2V you'll reverse bias the ref input transistor, giving a low-resistance path to ground. I mistakenly thought they have an internal fet-based comparator for the ref input, but it is transistor-based.

author: ralphd
author_rank: Frequent Contributor
timestamp: September 21, 2015, 06:28:08 pm
content: I measured the ref-cathode junction voltage drop on a few TL431s, and they were all very close to 0.73V @ ~0.5mA.http://nerdralph.blogspot.ca/2015/09/diodes-diodes-everywhere.html

author: nuno
author_rank: Frequent Contributor
timestamp: September 21, 2015, 07:37:56 pm
content: ralphd, I've never seen this value mentioned in an AVR datasheet, but an AppNote (I think it's the one on the mains zero cross detector) mentions that current through an AVR pin protection diode should not exceed 1mA.

author: ralphd
author_rank: Frequent Contributor
timestamp: September 21, 2015, 10:56:15 pm
content: Quote from: nuno on September 21, 2015, 07:37:56 pmProbably not a bad idea to keep the current low, but based on my measurements I'd guess that 10mA would not harm the AVR.

author: rr100
author_rank: Frequent Contributor
timestamp: September 23, 2015, 10:37:17 am
content: Yea, I was thinking there's a high impedance comparator too (and actually connected the Ref directly to the voltage I was "measuring" (lucky it was just a LiIon cell, the circuit still works...).
What hardware and software platform should I use for capturing certain signals - Page 1
Forum section: electronics / projects

author: ö
author_rank: Newbie
timestamp: August 26, 2020, 11:42:35 am
content: First of all, this is about capturing raw data from Digital Compact Cassettes () to explore the last secrets, preserve rare ones and possibly later record new ones with the full feature set. A copy of the full standard appeared, that and the fact that the audio codec PASC was later standardized as MPEG Audio Layer 1 and the standardization of the text-standard ITTS (IEC 61866, never used for anything else btw) make this project seem possible without too much Reverse Engineering:https://archive.org/details/philips-dcc-system-description-draft/I have the amplified binary signal from the DCC read amplifiers in two variants, parallel for each of the 9 tracks or time-multiplexed at 3.072 MHz with two clocks, one every 3.072 MHz for every individual track (the 10th timeslot is empty) and one 1/10 of that to indicate the start of the first track. The data rate including error correction overhead is roughly 1 MBit/s. The signal needs digital filtering (IIR and FIR) to account for distortion from the tape, so it has to be analog inputs (or programmable filters). The multiplexing seems like a cost-saving measure, but I hope for higher accuracy for fewer errors and thus dropouts by always capturing all tracks at the same time. It would be nice to have the same platform for easy testing and development as well as possible low-volume production that is modular enough that I can reuse most of the code for the two variants. Please tell me if nothing like this is reasonable and advise me what hardware and software comes closest:I thought about the following:Arduino: Discarded it right away, the sample rate, the bandwidth and the speed and the amount of analog inputs is far too low.Saleae logic analyzers: Promising for easy development, but I see little to no way for integrating it in more polished products.GNU Radio: FOSS and the modularity of software modules look very nice, but I did not find any supported hardware that goes down enough and has 9+ channels.MATLAB Simulink: Can allegedly work with many different types of hardware from the same model and code from microcontrollers to DSP and FPGA but is absolutely unaffordable when I am no longer a student and would completely kill collaboration.LabVIEW: Similar to Simulink, but the student edition is too restricted, so it is definitely not an option.Sigrok: FOSS and the support for the DS1054z look nice if I go the multiplexed route but basically the same problem as with Saleae, only relatively expensive logic analyzers available for 9+ analog channels and nothing that could be integrated.Separate ADC ICs: I did not find anything suitable.

author: ö
author_rank: Newbie
timestamp: August 26, 2020, 11:48:25 am
content: I accidentally deleted the Wikipedia-Link in the brackets before posting:https://en.wikipedia.org/wiki/Digital_Compact_Cassette@Mods feel free to put it in there and delete this post.
What I did this Weekend SCARA 28JBY STEPPER ARM - Page 1
Forum section: electronics / projects

author: Confus3d
author_rank: Newbie
timestamp: March 21, 2017, 03:15:47 am
content: First time posting here. I am a long time viewer of the EEVblog. I wanted to share my project and the current problems it faces. A number of weeks ago I purchased a few cheep stepper motors of Ali-express. I know, all the good stories start with buying cheep items from the east. These motors are bipolar and tiny. For 1.5 USD I each they came with a ULN2003 stepper motor driver that is suppose to connect to the IO pins of a micro controller. I got the idea in my head Friday to model a SCARA like robot arm using these motors and little else. (Pictures Below) I tend to learn the same way I explore. By starting with very few materials or planning. Does anyone have and expirence with SCARA arms, printers, and plotters? If so what tips to you have for building or programming one. I aslo wondered if anyone know a way to use these motors or drivers with the Marlin Firmware? Has anyone had any experience with these motors? This is just a quick exploration of the kinimatics. If I like the deisgn I could scale it up to NEMA 17 motors and a dedicated trinamic TMC driver.
What if the case over-voltage of the control supply of IPM occurred? - Page 1
Forum section: electronics / projects

author: Davis
author_rank: Newbie
timestamp: March 16, 2016, 03:09:03 pm
content: Hi everybody,Recently, i am working on a DC-AC inverter design using an IPM Module (PS22A78--MITSUBISHI).Unfortuately, during debugging test, all the lower bridges or all the IGBTS would be damaged unexcepted without any sign.My scheme is as the same as the recommended circuit in the datasheet of PS22A78.After a few days detection, i found that the control supply i designed had a little huge nosie about 3~4V voltage ripple as the attachments shows.So i doubt the case over-voltage of the control supply might occur.As the datasheet indicated, the IPM has a function of "under-voltage protection for control supply".However there is no cautions about what if the case over-voltage of the control supply occurred.So I don't know whether it is the root cause which is over-voltage happened that damage the IPM or not.If u have any suggestions, pls feel free to let me know.I'll preciate it if u could share any idea. Thank you a lot.