hybridfree/eevblog-posts huggingface dataset:
Is barrel jack DC input somewhat standardized? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: January 24, 2020, 06:17:17 pm
content: As the title suggest, is that thing standardized? Currently most of my projects are designed to expect either 7V-17V or 7V-30V, center positive input. (Most of my project uses 5V or 3.3V internally, which is generated from a barrel jack input using a buck converter TPS562200 or XL1509. TPS562200 supports up to 17V and XL1509 supports up to 40V, I don't have 50V rated SMT caps, so XL1509 based ones get 35V input caps and 30V input rating.) Is that a good design?

author: Bud
author_rank: Super Contributor
timestamp: January 24, 2020, 07:01:20 pm
content: Standardized in what regard? External supply voltage?

author: DBecker
author_rank: Frequent Contributor
timestamp: January 24, 2020, 07:36:16 pm
content: Nope, not at all.You would think that with the semi-standard size increments for the O.D. and center pin that the size would correspond to the voltage or current, but it doesn't. Even the polarity isn't ubiquitous, with some vendors preferring that their device blow up rather than lose a power brick sale to a generic product. (Yes, the insertion detection contact sometimes influences the polarity decisions, but most "reversed" devices don't have internal batteries to disconnect.)USB is a huge win as a power supply connection because the voltage and polarity are standardized, not at the whim of a marketing department.

author: tooki
author_rank: Super Contributor
timestamp: January 24, 2020, 09:07:39 pm
content: Broadly speaking, no, they are not standardized. There is one exception, though: the EIAJ connector standard, which maps specific voltage ranges to specific connector sizes that prevent accidentally feeding a higher voltage into a device. Sony and Panasonic largely used these on their gadgets for many years.https://en.wikipedia.org/wiki/EIAJ_connector

author: babysitter
author_rank: Frequent Contributor
timestamp: January 24, 2020, 09:17:13 pm
content: But a subset of them has been well standardised in DE but this is withdrawn!DIN 45323:1982-10 Connectors for coupling an external low-voltage power to portable entertainment equipmentOTOH, I used this standard last year to get matching barrel jack and plug.
is Chip Select a trap for low noise systems? - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: August 14, 2014, 06:00:57 am
content: I have a DAC, ADC and some digipots on my analog board. I thought it would be a good idea to save on isolators (everything is isolated) and use chip select. However, now I am thinking if i should give a separate network for the active SPI stuff then the static/calibration stuff.How much isolation can I expect from a chip select? Is it a crap shoot based on the part? Are there rules of thumb?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 14, 2014, 06:40:48 am
content: What are you isolating?

author: SArepairman
author_rank: Frequent Contributor
timestamp: August 14, 2014, 07:21:13 am
content: Quote from: T3sl4co1l on August 14, 2014, 06:40:48 amThe MCU.

author: jeremy
author_rank: Super Contributor
timestamp: August 14, 2014, 07:59:50 am
content: I'd be interested in the answer to this too.Although my strength is not low noise analog, I would have thought that most of your gains would be through just isolating the bus from the micro (is it galvanic? transformer? optical?) but I don't even know if this is necessary. Presumably, if they are mixed signal parts they are already designed for low noise applications? So you just need to be careful that you use a satisfactory power supply topology. I mean, my DSO is full of digital and analog stuff, and they're even on the same board with no isolation. I've only ever seen serious isolation when a) one side of a connector can't be trusted or b) the instrument is supposed to connect to a personedit: also c) when one side of the board has a stupendous voltage on it

author: David Hess
author_rank: Super Contributor
timestamp: August 15, 2014, 09:30:23 pm
content: Slowing the edge rate of the digital signals down at their sources with an RC filter will help a lot.

author: Bud
author_rank: Super Contributor
timestamp: August 16, 2014, 02:49:53 am
content: I worked with an 24-bit ADC and tested bus connection via RC-filters and direct and found no detectable difference in noise floor, even with other devices operating on that shared bus during ADC conversion period.

author: David Hess
author_rank: Super Contributor
timestamp: August 16, 2014, 03:01:52 am
content: Quote from: Bud on August 16, 2014, 02:49:53 amMany converters deliberately arrange to start conversions while the bus is likely to be quite but even without that, integrating converters have high inherent noise immunity. Digital noise is a much larger problem with sampling converters and in single ended designs where the analog ground gets pulled around.
Is chipmall Reliable? - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: March 16, 2022, 10:38:51 am
content: Hi,This is the first time that I want to buy fromhttps://www.chipmall.com/Are they Reliable? has any one experience with them?

author: thinkfat
author_rank: Unknown
timestamp: March 16, 2022, 12:22:12 pm
content: Now that's a funny one:I checked a few parts and their stock count matchesexactlythe stock of LCSC for the same part.I checked:MAX3089CSD+TP5400BQ250151N4148 (from Changzhou Starsea Elec)ESP32-C3-MINI-1-N4Coincidence? I think not...

author: thm_w
author_rank: Super Contributor
timestamp: March 16, 2022, 09:26:01 pm
content: They seem to have slightly more parts than LCSC, so they must be scraping some other vendors as well.Search sucks though, no way to sort by stock.

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: March 17, 2022, 07:21:00 am
content: Yes, their stock is exactly like LCSC, but the prices are a bit lower, any one tried them before?

author: thinkfat
author_rank: Unknown
timestamp: March 17, 2022, 07:35:12 am
content: They're new to me. But if they just mirror the catalog of other distributors (down to the stock count level) then they likely don't stock anything themselves.I'm not likely to try them myself. Since I'm not penny pinching, I see no advantage over buying directly from LCSC if I need "Asia Brand" parts. For other stuff I'm much more likely to buy from TME or Mouser. Especially TME can ship parts to me within one or two business days.
Is class D amplifer? Yamaha Stagepas diagram - Page 1
Forum section: electronics / projects

author: harrimansat
author_rank: Regular Contributor
timestamp: September 14, 2016, 08:00:41 pm
content: Hi folks,Can anybody help me with this schematic, Yamaha says that is a D class power amplifier, is a Stagepas 500 250W+250W RMS power amplifier 4 ohms, (+46V -46V).With only two 2SK3607 N 17amp mofests (70W mas power disipation) how it works???ThanksRegards

author: Ammar
author_rank: Regular Contributor
timestamp: September 14, 2016, 10:51:41 pm
content: https://en.wikipedia.org/wiki/Class-D_amplifier

author: ovnr
author_rank: Frequent Contributor
timestamp: September 14, 2016, 11:55:27 pm
content: Yes, that's a class D amplifier. As for dissipation: Remember, the maximum dissipation rating refers to how much power isdissipatedin the transistor - not how much flows through! And for a proper class D amp, the max dissipation figure is quite irrelevant for the maximum power output.

author: dannyf
author_rank: Super Contributor
timestamp: September 15, 2016, 01:38:37 am
content: Yes, it is class d. The first stage is a VI converter. The 2nd stage is a current transmission mechanism.The output is filtered pmw.Basically a power comparator. Aka ucd style.

author: diyaudio
author_rank: Frequent Contributor
timestamp: September 15, 2016, 07:11:50 pm
content: Quote from: harrimansat on September 14, 2016, 08:00:41 pmThis is a very good commercial amplifier to clone and diy its based on the Philips UCD self oscillating patent.A) Forms a simple differential output stage, the output will have a differential output swing which is identical to an op-amp with a complementary output stage. (you could replace A with a high speed op-amp with complementary outputs )B) A simple DTR fast turn off mosfet driver, this method is a cost effective technique to drive mosfetsby taming them for slower propagation turn on (to avoid turn on mosfet cross-conductance) yet allows fast turn-off response, turnoff is essentially grounding the gate almost instantaneously.C) Switching pair of N-channels, these will form a switching stage switching at the rate of least twice the audio frequency (using Nyquist Theorem) then feeding a LC stage used to demodulate the signal to audio.D) Forms are simple asymmetrical current sense trip for both +/- rails, if the amplifier is driving heaving speaker loads at high output levels it will signal a trip signal and shut the amplifier down.E) The most complex part, a pole/zero feedback system is used to create a phase/lag with compensation, its used to create feedback loop and get the amplifier to oscillate, the carrier residual used as a reference to create a PWM signal based on the difference between the two signals, note this system uses post feedback to obtain the carrier.

author: harrimansat
author_rank: Regular Contributor
timestamp: September 15, 2016, 08:56:51 pm
content: Thank you diyaudio, I really appreciate your answer.Philips demostration board patent:http://www.nxp.com/documents/user_manual/UM10155.pdf
Is CP2102 driver installation mandatory in windows10 desktops - Page 1
Forum section: electronics / projects

author: Sai teja
author_rank: Regular Contributor
timestamp: December 09, 2017, 07:07:02 am
content: Hello , I am using CP2102 Serial driver IC in my project. When using CP2102 with my laptop (window 10) , COM port detected automatically. But the same CP2102, when I am using with Desktop(windows 10), COM port didn't detected. I had to install drivers manually and it worked. What might be the reason for this behaviour?
Is  CR-2477/VCN acceptable replacement for BR-2477/VAN ? - Page 1
Forum section: electronics / projects

author: plantgrower
author_rank: Contributor
timestamp: June 20, 2013, 11:41:58 pm
content: I have an agilent 34970a which currently has a PANASONIC - BR-2477/VAN battery soldered in it that needs replacing is a CR-2477/VCN a suitable replacement as the BR variant is not available.

author: Stonent
author_rank: Super Contributor
timestamp: June 21, 2013, 01:09:19 am
content: I'd say yes, but.... BR are designed for more temperature tolerance than CR batteries. If the battery is helping store calibration data, I'd make sure to some how wire up some 3V power in parallel to the battery so that you don't lose data when it is removed.Technical Data - Table 1 - (CF)n/LI: Poly-Carbon Monofluoride (BR)Technical Data - Table 2 - Mn02/LI:Manganese Dioxide (CR)http://www.panasonic.com/industrial/batteries-oem/oem/primary-coin-cylindrical/br-cr.aspxQuoteQuoteTo be safe, probably should stick with the BR battery, you don't want it popping and ruining your nice gear.

author: Stonent
author_rank: Super Contributor
timestamp: June 21, 2013, 01:14:02 am
content: Ok scratch the part about CAL datahttp://www.home.agilent.com/agilent/editorial.jspx?cc=US&lc=eng&ckey=1000001022:epsg:faq&nid=-11143.0.00&id=1000001022:epsg:faqQuote

author: plantgrower
author_rank: Contributor
timestamp: June 21, 2013, 03:56:01 am
content: Quote from: Stonent on June 21, 2013, 01:09:19 amDoes anybody know a stockist of a BR-2477/VAN in the UK please ? Digikey list the Panasonic part but no stock

author: Stonent
author_rank: Super Contributor
timestamp: June 21, 2013, 04:35:33 am
content: Quote from: plantgrower on June 21, 2013, 03:56:01 amLooks like you just have to wait 2 weeks. I entered 1qty and got this:Quote

author: Stonent
author_rank: Super Contributor
timestamp: June 21, 2013, 04:40:24 am
content: Allied has them for export:http://www.alliedelec.com/search/productdetail.aspx?SKU=70196835Newark alsohttp://www.newark.com/jsp/search/productdetail.jsp?SKU=40T0046&CMP=AFC-OPFJust to be sure, does your battery stand up or sit flat?

author: nukie
author_rank: Frequent Contributor
timestamp: June 21, 2013, 05:34:50 am
content: Microbattery.com

author: plantgrower
author_rank: Contributor
timestamp: June 21, 2013, 07:10:35 am
content: Quote from: Stonent on June 21, 2013, 04:40:24 amStands up on its edge.Quote from: Stonent on June 21, 2013, 04:35:33 amI just noticed that too thanks. Looks like I'll just have to wait.

author: matemathieu
author_rank: Contributor
timestamp: April 28, 2017, 02:19:40 pm
content: For the record, I have changed the battery in the same Agilent 34970A chassis.It was a SANYO cR14250SE already, so I have just replaced it.
is DAC settling time linear? - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: March 14, 2014, 08:24:21 pm
content: If I have a dac that has a settling time of x for its full scale, and I only need a transition of 1/10th full scale, can I effectively divide the settling time by 10 for design purpose?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 14, 2014, 09:32:44 pm
content: Settling time, ringing, rise time and so on are governed by wildly nonlinear functions (at best, a series of real and complex exponentials), so any general statement is impossible.On the upside, settling time (as a percentage of the transition size) tends to be fairly constant, due to various filtering elements in the circuit being more-or-less linear. Roughly speaking, a 100mV transition will settle within 0.1% (0.1mV) in about the same time as 10mV settles within 0.1% (0.01mV -- assuming noise and interference are small enough to resolve such a small error).But if you only need it within 0.1mV absolute (which is 0.1% for the first case, 1.0% for the second), the second case will be faster -- but it's impossible to calculate by how much. If the settling occurs along a single RC time constant, it will be about 1/10th the time, but real circuits are generally more complicated than that.Tim

author: nctnico
author_rank: Super Contributor
timestamp: March 15, 2014, 12:57:03 am
content: Quote from: SArepairman on March 14, 2014, 08:24:21 pmNo. The settling time depends on many factors including how many bits change and which bits change. For some applications this can cause problems because the DAC outputs extra 'switching' noise.
Is dc dimmer a dc buck coverter  - Page 1
Forum section: electronics / projects

author: abdulbadii
author_rank: Frequent Contributor
timestamp: November 30, 2022, 11:53:51 am
content: Is mostly market found dc dimmer a dc buck coverter ?Anyone please generous enough elaborate its function circuit blocks

author: Terry Bites
author_rank: Super Contributor
timestamp: November 30, 2022, 12:19:16 pm
content: For an LED dimmer?This would be a controlled current source.See a typical driver with circuit fucntions explainedwww.infineon.com/dgdl/Infineon-ILD8150_ILD8150E-DataSheet-v01_05-EN.pdf?fileId=5546d462696dbf120169ba96613f4c20

author: Siwastaja
author_rank: Super Contributor
timestamp: November 30, 2022, 12:51:22 pm
content: No idea. You would need to post an example of what you think is a "mostly market found dc dimmer", then we can guess.Optimum way to drive LEDs is a constant-current power supply, which internally provides adjustable current, and has a control input. In such case the "dimmer" would be just a controller which drives the control input.If the "dimmer" is a separate product which takes DC voltage in and then drives the LEDs, then it - at least hopefully - does constant current regulation and turns the non-optimal voltage based power supply into better-for-LED current source. Buck is a very likely topology to implement this.Or, the separate dimmer could be something as simple as an adjustable resistor. Who knows, there is a lot of crap on the market.

author: ajb
author_rank: Super Contributor
timestamp: November 30, 2022, 03:28:58 pm
content: A standalone "DC dimmer" designed for constant-voltage LED loads (for example 12V LED tape), if that's what you're talking about, is just PWM. Its functional circuit blocks would include some sort of PWM signal generator (maybe a 555, maybe an MCU) and a transistor, that's about it. If you added a second transistor or a diode (which might already be present if the dimmer was also designed for inductive loads like motors), an output inductor, and some feedback, then you'd have a buck converter.There are also dimmable LED drivers in both constant current and constant voltage mode variations that I suppose you could refer to as a 'DC dimmer'. One of those that operates from a DC input might be a buck converter, but ones that operate off of AC line voltage likely use a different topology.
Is DH321 the same as Fairchild FSDH321? - Page 1
Forum section: electronics / projects

author: TheRuler8510
author_rank: Regular Contributor
timestamp: March 03, 2015, 03:14:48 am
content: Is DH321 the same as Fairchild FSDH321?If so, what is the meaning of "BH51" in second line in the ebay link below? I mean to replace a chip with "VH05" and I wonder if this chip will suffice:http://www.ebay.com/itm/1PCS-DH321-Panel-PCB-Mount-IC-Chips-/181594060645?pt=LH_DefaultDomain_0&hash=item2a47d97765Thanks,
Is EEPROM program voltage timing critical? - Page 1
Forum section: electronics / projects

author: Things
author_rank: Regular Contributor
timestamp: January 02, 2013, 10:33:13 am
content: Hey guys, I'm kind of new to external EEPROM programming on IC's, and the one I'm using needs an external EEPROM program voltage of 14V.In the datasheet, it says to enable this 14V, wait 16ms, then disable it again. My question is, does this mean it can _only_ be on for 16ms, or would plugging it in, then "quickly" unplugging it by hand be sufficient?Cheers,Dan

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 02, 2013, 11:42:53 am
content: A partnumber or link to datasheet would help...

author: grumpydoc
author_rank: Super Contributor
timestamp: January 02, 2013, 11:44:48 am
content: But in general, if that's what the datasheet says to do, then do it.If you're lucky your device won't program. If you're less lucky you'll probably fry it.

author: JoannaK
author_rank: Frequent Contributor
timestamp: January 02, 2013, 12:03:26 pm
content: Also, be sure to install current limiting resistor (if possible) and to be sure voltage rise/fall times meet the specs. And note, that too fast rise time (or ringing) can often burn the chip.So, read the datasheet, documentation of the chip programming andErratas available. Quite ofthe reading the errata saves the day, or week.
Is exceeding the PIV of a diode by 3 x tolerable in any instance? - Page 1
Forum section: electronics / projects

author: tom66
author_rank: Super Contributor
timestamp: November 23, 2014, 11:21:47 pm
content: I've been repairing a lot of 17PW25-4 power supplies. I've repaired 4 so far in the space of about 6 months. They are utter junk. They have the same failure mode: a shorted diode on the secondary and damage to the primary side, blown mains fuse, shorted FET.The original power supply uses UF5402 (3A, 100V) diodes on the output (8 in parallel!) I have used HER308G (3A, 1kV) to replace them. This is for the 24V, 6A output.I scoped the anode of the diodes on power up - the original UF5402 are 100V rated... there are repeated transients of up to 280V on the cathode when the power supply is turned ON (this is not AC plug in, this is turn on from standby) occuring over about a 2ms period.I suspect this is why these power supplies are failing. Could this kill diodes? I haven't been able to measure the current, so I can't be sure this is dumping much energy into them. But it cannot be good, right?

author: edavid
author_rank: Super Contributor
timestamp: November 23, 2014, 11:33:12 pm
content: The UF5402 is actually a 200V rated part. Are they breaking down at 280V? It doesn't look like it from your scope trace.

author: tom66
author_rank: Super Contributor
timestamp: November 23, 2014, 11:38:40 pm
content: Good point, I will make sure but I think they might have been UF5401s. I do recall them being 100V rated parts.This scope shot was taken with 1kV diodes installed (HER308G) after the PSU was repaired.Forgot to mention, the transients only occur when switched on. Once operating, the inverse voltage across the diodes is about 60~70V maximum.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 24, 2014, 01:02:24 am
content: Try a ferrite bead in series with each diode (which will help with transient current balance as well), and an R+C across the diodes (you'll have to find correct values, but I would vaguely guess 10 ohm and 2nF would be a starting point).It doesn't look like you even have enough bandwidth to observe the phenomenon. It may be faster, crunchier or squarer than you can see.Or even better, see if you can fit a proper TO-220 style device somewhere.Tim
Is GND  required for two independent modules to communicate in MIL STD-1553  - Page 1
Forum section: electronics / projects

author: electronx
author_rank: Regular Contributor
timestamp: January 27, 2024, 12:51:15 pm
content: I use Holt IC 2130 mil std1553 trasceiver. When I connect only the A and B differential lines in two independent modules, I cannot communicate between the two modules, but when I connect the GND pins, the communication is completed successfully. so Is GND connection required for two independent modules to communicate in MIL STD 1553 protocol? Or is there another point I missed? As far as I know, GND connection is not required for differential lines.Source: Holt IC AN-550https://smallpdf.com/result#r=aa4b30d6011942438c3436c435231433&t=share-document

author: moffy
author_rank: Super Contributor
timestamp: January 27, 2024, 02:02:09 pm
content: mil-1553 is a fully isolated, no DC Manchester encoded bus, it should not require a gnd connection between devices.
Is internal pull-up a problem for enable pin on regulator or power switch? - Page 1
Forum section: electronics / projects

author: Sarcarean
author_rank: Contributor
timestamp: September 14, 2016, 10:36:51 am
content: So I am finishing a design and I believe there could be a potential problem, so I thought I would toss this over to the pros here.I have a Atmel ARM micro-controller connected to the enable pins of two high-side power switches (ADP197), with each one controlling the output of 5v or 3.3v.The potential problem is that the Atmel MCU GPIO has internal pull-ups (100K?) on bootup/reset, and the power switch has an internal pull-down (4 M?). I am worried that on boot, both power switches will become active (and thus combined voltage would do damage). My design is to enable one switch or the other, but not both at the same time.So my question is: is there a problem here? And if so, should I connect a resistor (4.7K?) to each of the enable lines to ground?

author: ajb
author_rank: Super Contributor
timestamp: September 14, 2016, 11:48:28 am
content: Yes, it's up to you to make sure that your system doesn't blow itself up when the MCU is in reset. However, are you sure that the pullups are active on reset? Usually the outputs are off entirely, in which case the the internal pulldown in the switches should keep them off. But resistors are cheap, and a footprint for a resistor you might or might not need is even cheaper, so I'd say put the footprint there in any case. If it turns out that you don't need the resistor, great, if you do, good thing you have a place for it!
is it any good? linear bench power supply - Page 1
Forum section: electronics / projects

author: xReM1x
author_rank: Regular Contributor
timestamp: September 27, 2015, 07:15:36 pm
content: http://cds.linear.com/docs/en/lt-journal/LTJournal-V24N2-02-df-BenchSupply-Szolusha.pdf

author: microbug
author_rank: Frequent Contributor
timestamp: September 27, 2015, 07:34:02 pm
content: I don't see why not.

author: prasimix
author_rank: Unknown
timestamp: December 15, 2015, 07:47:20 am
content: Yes, it is. Programmable version of it is in the core of thisproject.
Is it common to underrate the voltage of motor start capacitors? - Page 1
Forum section: electronics / projects

author: calzap
author_rank: Frequent Contributor
timestamp: November 12, 2020, 11:09:47 pm
content: Recently had the start capacitor fail on a 240 VAC, 3 HP motor. When I read the label, I was surprised to see it was rated 500 uF, 125 VAC. The run capacitor is 30 uF, 250 VAC. Did the manufacturer assume the lower voltage rating would be OK for the start capacitor because the centrifugal switch quickly takes it out of circuit?I’m replacing the failed capacitor with one rated 500 uF, 250 VAC. Unfortunately, it’s physically bigger and won’t fit in the pod on the side of the motor. I’m thinking of making a new pod from a food tin unless someone has a better idea.Mike in California

author: TheMG
author_rank: Frequent Contributor
timestamp: November 13, 2020, 12:50:39 am
content: The voltage across the start capacitor is likely to be much lower than the voltage across the run capacitor. It's a much larger capacitor thus will have a lower impedance, and therefore smaller AC voltage across it (and more voltage on the motor winding).
Is it difficult to cut a slot in a powdered iron toroid? - Page 1
Forum section: electronics / projects

author: e100
author_rank: Frequent Contributor
timestamp: May 08, 2024, 06:33:37 am
content: I'm following this pagehttps://softsolder.com/2014/09/18/current-sensing-powered-iron-toroid/What actually holds the iron particles together? Is it some sort of thermoset resin?Do I need to worry about chipping, or it suddenly crumbling into pieces?I only have hand tools and a Dremel with a variety of carbide and diamond cutters.

author: coppercone2
author_rank: Super Contributor
timestamp: May 08, 2024, 06:44:54 am
content: I feel like those CBN dremel wheels are the best for cutting stuff like that.Diamond is best for like ferrite ceramic type inductors, and the hard part is cutting it under water because it likes to shatter.I don't think you need diamond for powered IRON.I think they use pressure glue. That is glue that bonds under high pressure in a mold. It is probobly a few percent additive (that is, if they use anything special at all).unless you have something that is 'glass like' , you don't need diamondsThe newest ones have inorganic binder. I don't know how that works. Maybe they add some metal that deforms to cold sinter it or something. patent says aluminum phosphate matrix. But I still recon its soft and you don't need diamonds. Water glass might be used tooI cut into granite with a steel rod in it with CBN wheel

author: jonpaul
author_rank: Super Contributor
timestamp: May 08, 2024, 07:12:48 am
content: WHY? Really there is no reason to cut a powdered iton toroid.Because, powdered iron toroids are inherent gapped, distributed.see excellent Micrometals cats and app notes.https://micrometals.com/Jon

author: coppercone2
author_rank: Super Contributor
timestamp: May 08, 2024, 07:17:56 am
content: Quote from: jonpaul on May 08, 2024, 07:12:48 amthe inherent gap in the powered iron core is the reason why the slope is gentle for this inductor type?

author: RoGeorge
author_rank: Super Contributor
timestamp: May 08, 2024, 07:38:24 am
content: Quote from: jonpaul on May 08, 2024, 07:12:48 amIn the OP link, the gap was cut to insert a Hall sensor in the magnetic path, in order to make a load/current sensor. A Dremel was used to cut a gap, and it worked. I would cut that outside, and with a mask, for just in case the ferrite glue and dust is nasty.A single hit with a hammer, while the core is in a vice, so to break in two should also work. Since the exact parameters of the core doesn't matter, the sensor can be as well made out of two pieces glued with the Hall sensor in the magnetic circuit.Then, there is the possibility to let the core intact, and use it as a current transformer, unless it must measure down to DC.
Is it good PS project? Any alternatives? - Page 1
Forum section: electronics / projects

author: 001
author_rank: Super Contributor
timestamp: September 09, 2018, 08:48:48 am
content: Hi!I wanna build simple linear power supply with voltage and current modesIs it project Okhttp://www.electronics-lab.com/project/0-50v-2a-bench-power-supply/? Any opinions/alternatives?Thanx

author: prasimix
author_rank: Unknown
timestamp: September 09, 2018, 09:50:29 am
content: This design is discussed hundred of times on this forum and elsewhere. If you need good and simple design perhaps you can try this one:LM10 Linear Power Supply 0-50V 0-2A with temperature protection.

author: 001
author_rank: Super Contributor
timestamp: September 09, 2018, 02:41:26 pm
content: Quote from: prasimix on September 09, 2018, 09:50:29 amThanx!Where I can read this?Any conclusion?

author: Kleinstein
author_rank: Super Contributor
timestamp: September 09, 2018, 03:36:48 pm
content: The circuit from the 1st link is actually a variant of the LM10 circuit.A rather long thread on one type of power supply is this one:https://www.eevblog.com/forum/beginners/bangood-psu-enhancements/It starts with a cheap kit and fixes the main issues. With the fixes the circuit is Ok, though limited in the voltage range by the OPs used. The main point it that the kit advertised at 30 V and 3 A is good for 20 V and maybe 1.5 A, maybe 2 A.Another type of lab power supply are build similar to the older HP ones, with a floating regulator and thus usually a 2nd transformer. This type is also used in quite a lot of the cheap commercial supplies. It's a little more tricky, but very flexible to also work to higher voltages if needed.

author: 001
author_rank: Super Contributor
timestamp: September 09, 2018, 05:07:34 pm
content: Quote from: Kleinstein on September 09, 2018, 03:36:48 pmWhat schematic do You mean?

author: xavier60
author_rank: Super Contributor
timestamp: September 10, 2018, 12:38:53 am
content: I recently had good results building a floating type regulator. I found it difficult getting used to the + output being the ground reference for the control circuitry.I didn't copy any particular circuit, only the basic way in which most of these regulators work. One op-amp for the Voltage Control loop and one op-amp for the Current Control loop.The output pins of the 2 op-amps are diode ORed together so that either can take control of the Gate of a large MOSFET which functions as the series pass element.The circuitry in the red outline is only there for interfacing to a micro-controller which isn't necessary.In my project, the regulator is fed from a 600W SMPS. I don't recommend doing the same. A conventional mains transformer with secondary tap changing would be best.
Is it me or this is wrong - Page 1
Forum section: electronics / projects

author: dardosordi
author_rank: Regular Contributor
timestamp: January 21, 2017, 03:04:36 am
content: I stumbled upon this circuit, it comes from the data sheet but I think it is just wrong. At the minimum value for the pot you will get a significant current flowing from the positive output to the negative output on the divider.Data sheet:http://cds.linear.com/docs/en/datasheet/1033fd.pdf

author: Brumby
author_rank: Unknown
timestamp: January 21, 2017, 03:56:58 am
content: Here's a hint....What will the +/- Voutbe when the 5K potentiometerisat it's minimum?

author: dardosordi
author_rank: Regular Contributor
timestamp: January 21, 2017, 04:03:24 am
content: 1.2 v x 2 = 2.4vI = 2.4v / 200 ohm = 12mA ... I guess it's ok. Thanks.

author: PMOS
author_rank: Newbie
timestamp: January 22, 2017, 06:44:15 am
content: How does that circuit behave if one of the regulators goes into current-limiting mode?

author: BravoV
author_rank: Super Contributor
timestamp: January 22, 2017, 07:14:49 am
content: Does this circuit work at vintage LM317 & LM337 pair ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 22, 2017, 09:37:11 am
content: Quote from: PMOS on January 22, 2017, 06:44:15 amTracking is tracking.Quote from: BravoV on January 22, 2017, 07:14:49 amYes.Tim

author: Gyro
author_rank: Super Contributor
timestamp: January 22, 2017, 10:16:29 am
content: Quote from: T3sl4co1l on January 22, 2017, 09:37:11 amI'm not sure that it does play nicely if one output is shorted (or current limits). In normal operation part of the reference divider network for each regulator is biased to the output of the opposing regulator. If one output is shorted the whole of the network of the opposing regulator will become referenced to ground instead. That must surely cause its output voltage to increase. I think it needs a dual gang pot referernced to ground to work correctly.
Is it normal for CMOS mcu’s to be lukewarm when running at full speed? - Page 1
Forum section: electronics / projects

author: AndersJ
author_rank: Frequent Contributor
timestamp: September 20, 2020, 04:13:46 pm
content: I have several products in production using Freescale/NXP HCS08 and HCS12 devices.The HCS chips are all running slightly warm.I am worried I might have misconfigured I/O lines causing unwanted power consumption.Perhaps unused I/O that is not available externally due to my use of smaller packages.As far as I can tell this is not the case,but I am uncomfortable with lukewarm CMOS devices.Am I overthinking this?Is this perhaps normal when running these devices at full speed?

author: Zero999
author_rank: Super Contributor
timestamp: September 20, 2020, 04:18:57 pm
content: You haven't posted enough information.My gut feeling is yes, this is normal, but would have to see more data to be sure.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 20, 2020, 04:27:51 pm
content: Look at datasheet typical power consumption, and package thermal resistance. Temperature rise is P * Rth.Depending on MCU, temperature rise under "typical" say half of peripherals on, running at near-full or full speed, may be just 1-2 degrees or it could be 50 degrees. A small Cortex-M0 in a relatively large package may not heat up much, but a flagship STM32H7 dissipates 0.5W when powered from external Vcore, or some 1.3W when powered with the integrated LDO, bringing it easily close to Tj=100 degC even at modest ambient temperatures.

author: Benta
author_rank: Super Contributor
timestamp: September 20, 2020, 04:36:42 pm
content: HCS08s shouldn't run warm, a slight rise is OK. HCS12s can run a bit warmer, lukewarm is OK.Misconfigured I/O can usually only give problems if connected directly to VDD or GND without pullup/down resistors.

author: tkamiya
author_rank: Super Contributor
timestamp: September 20, 2020, 05:19:22 pm
content: You may want to measure how much current it's pulling. CMOS is knowing for low power operation but at high duty rate, it does consume power and does get warm. LUKE warm sound pretty normal to me. Spec sheet should tell you what to expect.
Is it normal not to be able to place stackable headers adjacent lengthwise? - Page 1
Forum section: electronics / projects

author: kesterlester
author_rank: Newbie
timestamp: January 11, 2021, 10:36:08 pm
content: My question is: Is it normal for stackable headers to be wider than 0.1in times the number of pins to the extent that you can't expect to place them against each other in a line?For a small project I designed a PCB with a row of 13 holes at 0.1in spacing to hold a length-13 run of stackable headers. Since 13 is a strange number, I planned actually to just put two 5-er headers and one 3-er header in a line. (13=5+5+3) The PCB arrived from the fab today. To my great disappointment (see attached picture) I have found that I can't actually place my headers in a line!Although the PCB holes are exactly 0.1in spacing, and though the header pins are also exactly 0.1in spacing, it seems that the total width of my 5-er headers is not 0.5in but more like 0.52in.I suspect if I sit down for long enough with a piece of sand paper I shall be able to sand the plastic down at each end of my headers, and ultimately I will be able to get them to fit adjacent to each other. And if there are many of you out there who will tell me that what I've seen is entirely normal (i.e. that bought most stackable headers don't sit adjacent to each other) then I will get out the sand paper and do just that.But if instead you report that 99% of headers sit beside each other without problem, then I will just go out and buy a few more headers from a reputable supplier, and will remember never to by cheap headers off ebay again ...

author: langwadt
author_rank: Super Contributor
timestamp: January 11, 2021, 10:58:19 pm
content: ime it is common for most female headers

author: kesterlester
author_rank: Newbie
timestamp: January 11, 2021, 10:59:32 pm
content: OK - sand-paper it is. Thank you.

author: Microdoser
author_rank: Frequent Contributor
timestamp: January 12, 2021, 12:31:38 pm
content: Yes, each socket has a full wall at each end, but between two sockets along a row there is only a single wall, so putting two ends together means a double wall. You would need to either remove one wall or sand them down to half a wall.

author: dl6lr
author_rank: Frequent Contributor
timestamp: January 12, 2021, 05:13:22 pm
content: Get headers with more contacts (i.e. 20), remove the 14th contact und cut the housing there with a saw. Then sand it down. I've done that with a lot of female headers.
Is it Okay to use 14.5v power adapter on a laptop requiring 14v? - Page 1
Forum section: electronics / projects

author: kasojige
author_rank: Newbie
timestamp: March 26, 2019, 09:02:45 am
content: Hello, one of my friend lost his laptop power adapter, and he picked up a 14.5v one, used it for several times until I knew that. I think it's not good to use a adapter with higher voltage, but does it really matters, if he continue to use it? Also can we modify that existing adapter to change the voltage a bit, instead of buying a new one? Thanks.

author: brabus
author_rank: Frequent Contributor
timestamp: March 26, 2019, 09:45:30 am
content: 14,5V is only 3,5% higher than 14,0V. Such a variation should be tolerated by the laptop electronics without major issues, so I would just keep using it, not even bothering with lowering the voltage.

author: digsys
author_rank: Unknown
timestamp: March 26, 2019, 09:53:50 am
content: Agree with above. You'll rarely find anything these days that can't cope with +- 5-10% variation. They all drop a volt or more under load anyway.
Is it possible to change the output voltage here? - Page 1
Forum section: electronics / projects

author: Chet T16
author_rank: Frequent Contributor
timestamp: July 25, 2017, 06:57:47 am
content: I have an LED driver here with an output of 72V, unfortunately it has an unknown IC so I've no datasheet to see how the voltage is set.Presumably its a matter of changing a couple of resistors? Any pointers on where to start?Thanks

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 25, 2017, 07:38:38 am
content: Quote from: Chet T16 on July 25, 2017, 06:57:47 ami salvaged led light from dumbster (similar size as long flourescent tube). the chip driver is WS3441A offline non isolated led driver. its constant current driver instead of constant voltage. so i guess you put anything on the output, it will produce any voltage necessary to get the set constant current... the chip number is barely visible in the picture you posted, maybe you can clean some more and look the number under microscope, ymmv.

author: Zero999
author_rank: Super Contributor
timestamp: July 25, 2017, 08:12:57 am
content: Quote from: Mechatrommer on July 25, 2017, 07:38:38 amYes, it's most likely it regulates the current, not the voltage, which is probably limited to 72V to protect the components. It's also quite likely it either isn't isolated from the mains at all or the insulation isn't adequate to enable the DC side to be treated as non-hazardous.

author: Chet T16
author_rank: Frequent Contributor
timestamp: July 26, 2017, 11:44:05 am
content: Yes its non-isolated but it only needs to run for a short while under controlled circumstances for some testing.I'll do some testing to see if it is indeed constant current.Thanks
Is it possible to connect 6 two-wire RTDs to ADS124S08 Analog to Digital Convert - Page 1
Forum section: electronics / projects

author: ashmit_jaiswal
author_rank: Newbie
timestamp: September 20, 2024, 04:25:35 pm
content: I have connected 6 two wire RTDs to a ADS124S08 Analog to Digital Converter in series and parallel connection. My requiernments are to connect as many RTDs as possible to the chip with least amount of extra equipment and to achieve a mix between accuracy and number of RTDs.The attached image is a schematic of 6 Two Wire RTDs connected to a ADS124S08 Analog to Digital Converter. I would like to know the following things about my idea:1) Will the AINCOM pin acting ac IDAC1 be complying with the load of 6 RTDs? 2) Will there be any division of current across the 3 sets of 2 RTDs and if yes, then will it affect the functionality of the RTDs [Parallel connection]2) Will there be any distorting in the readings of the RTDs? If yes, then till what extent and will it be filterable by any hardware or software?3) Is there any chance of any unexpected error which I have not predicted yet?4) Is there any other way/schematic to achieve this objective?5) which of the two methods is better?

author: zapta
author_rank: Super Contributor
timestamp: September 20, 2024, 05:16:48 pm
content: Your software will need to derive the resistance of each of the 6 RTDs. I suggest to assign actual numbers (e.g. PT100 vs PT1000, resistor values, IDAC currents, etc) and:1. Write the formulas for the 6 resistances.2. Verify that you are within the working range of the ADS124S0x (e.g. the input voltages that you get on the ADC and reference inputs).3. Compute the expected worst case resolution (ideal ADC steps / Ohm, at the worst temperature points).The second design is more intuitive because the resistance formulas are independent for each channel (#1 above).

author: Salitronic
author_rank: Contributor
timestamp: September 21, 2024, 07:06:21 am
content: Unless I am missing something, you have an underdetermined system, you cannot calculate the individual RTD resistances by this system.You only know the total current going through the 3x2 RTD array and the voltage across each RTD.The current in each parallel branch will be different, so you have 9 unknowns (6 resistances and 3 currents) and not enough equations to calculate it.

author: ashmit_jaiswal
author_rank: Newbie
timestamp: September 24, 2024, 04:30:37 pm
content: so in the schematic where the RTDs are connected in series can we calculate the resistance of each RTD using the reference current or is there another method to do that. Also please tell me what errors we can expect.
Is it possible to damage a MMBT3904 with overvoltage through current limiting R? - Page 1
Forum section: electronics / projects

author: incf
author_rank: Frequent Contributor
timestamp: April 26, 2025, 01:39:47 pm
content: The MMBT3904 has a breakdown voltage of 40V.Suppose a supply voltage of 100V is applied to the collector through a 10k resistor.Can exceeding the breakdown voltage cause damage, when it is current limited?My impression is that BJTs are quite robust (compared to FETs, etc.) against this. And that it will turn into an ~40 to ~50V avalanche diode until the supply voltage drops below the breakdown voltage.

author: bdunham7
author_rank: Super Contributor
timestamp: April 26, 2025, 02:02:15 pm
content: https://toshiba.semicon-storage.com/info/application_note_en_20210303_AKX00048.pdf?did=63509You should read both the voltage ratings and SOA/secondary breakdown parts.I think the short answers are "maybe" and "10k might not be enough".

author: moffy
author_rank: Super Contributor
timestamp: April 27, 2025, 02:06:05 am
content: It will probably be OK, but it might degrade slightly with time, but one off should be OK.P.S. There are fast pulse circuits that repeatedly avalanche a transistor with high voltage that seem to work repeatedly.

author: bson
author_rank: Unknown
timestamp: April 27, 2025, 08:26:49 pm
content: It's not the voltage that's the problem, it's the avalanche current. As soon as the junction breaks down there's a rush of current, the voltage drops and the current drops. In a steady state circuit like this which isn't pulsed you get continuous such buildup and breakdown, resulting in noise. The only way to really know if this damages the transistor is to try it and measure the current and junction temp (or its package temp as a proxy). I'd be amazed if there's any practically usable model for this.

author: Ian.M
author_rank: Super Contributor
timestamp: April 27, 2025, 09:37:13 pm
content: Its known that reverse bias breakdown of the base emitter junction typically degrades current gain, even at fairly low breakdown currents. Therefore, its not unreasonable to suspect that much higher energy avalanche breakdown cascades the other side of the extremely thin base layer may also degrade transistor characteristics possibly increasing leakage current. However there is a lot of prior art deliberately using BJTs in avalanche mode - seehttps://en.wikipedia.org/wiki/Avalanche_transistorfor references - so for devices with appropriate structure and doping profiles, degradation must be manageable.

author: MariuszD
author_rank: Regular Contributor
timestamp: May 20, 2025, 12:04:18 pm
content: Quote from: incf on April 26, 2025, 01:39:47 pmAvalanche rated MOSFETs are everywhere, avalanche rated BJTs are rare.Some old transistors have several breakdown voltages specified in datasheet Vce Vcb Vcer.
Is it possible to disable the touch pad on a TTP223 Capacitive Touch Module? - Page 1
Forum section: electronics / projects

author: Hootis Tigglebits
author_rank: Contributor
timestamp: November 03, 2023, 05:12:42 am
content: I'm using an external touch trigger on a TTP223 and was wondering if it's possible to disable the touchpad on the back of the TTP223?

author: floobydust
author_rank: Super Contributor
timestamp: November 03, 2023, 05:17:06 am
content: Yes, you have to cut the PCB trace going to it, to disconnect the touch pad.Then add a wire from the IC to your external one. It depends on your board, some make this easy, others are a pain.

author: Hootis Tigglebits
author_rank: Contributor
timestamp: November 04, 2023, 06:19:09 pm
content: Thanks!