hybridfree/eevblog-posts huggingface dataset:
Feet - Page 1
Forum section: electronics / beginners

author: fabiodl
author_rank: Frequent Contributor
timestamp: March 07, 2021, 03:46:11 am
content: Do you put feet on your boards / enclosures?What do you use?I like the idea used in the DE10-nano (see attached picture) but I never found these kind of silicone feet for sale.I also like thesescrew on feetbut they are pretty expensive.I saw people hand making them with motorsil (https://bit.ly/3kZQLz6)but I'd like to know what solutions / sources you use.

author: bob91343
author_rank: Super Contributor
timestamp: March 07, 2021, 04:08:50 am
content: Threaded spacers are cheap, or they at least used to be.

author: ataradov
author_rank: Super Contributor
timestamp: March 07, 2021, 04:41:52 am
content: But those rubbery caps are not easy to find.It may possible to use nylon threaded spacers, but the rubbery ones are nice, since they don't slide.Sticky rubber feet are another option.

author: bob91343
author_rank: Super Contributor
timestamp: March 07, 2021, 06:28:46 am
content: Just a screw and nut.

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: March 07, 2021, 07:12:16 am
content: Adhesive silicone rubber feet, in black or clear. They're cheap, low profile, and super grippy.
Ferrite Bead and Parasitic Oscillation - Page 1
Forum section: electronics / beginners

author: Yaro
author_rank: Contributor
timestamp: February 23, 2015, 11:15:17 am
content: Hi all,I want to ask how to correctly choose a Ferrite Bead to use with a circuit. I've recently tested a digital signal from one circuit with a 20cm cable. The signal tested was 0.30Hz and 10kHz. I've found a lot of parasitic oscillation on signal and solved this problem adding a ferrite to the signal cable.In the case are not used cables but pcb lines, what I want to ask is:- Given a signal frequency range, voltage and current consumption, how correctly I should choose FB SMD parameters(Freq. and current)- In the case of a lot of pcb lines, to avoid parasitic oscillation and the use of multiple FB, is the same to place FB on power supply output or signal?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 23, 2015, 11:47:47 am
content: What is the nature of the circuitry at either end of this trace? What is the nature of this "oscillation"?A ferrite bead (in the linear range*) acts as a lossy inductance over a broad range of frequencies. Typical cases include dampening sharp edges from digital logic sources (the high impedance at high frequencies attenuates the edge, while the low impedance at low frequencies passes much of the intended signal), or reducing radiated emissions/susceptibility of long traces or outside wires (especially in combination with ceramic chip capacitors, forming damped LC lowpass networks).*Saturation current is typically less than 10% of rated current, so even for very large chips, you can assume their properties are only valid for small signal currents. Ferrite beads on any kind of power line (carrying >20mA DC) are rather futile. For DC or power line filtering, choose "multilayer chip inductors", which are intended to carry DC, and cost the same as ferrite beads; or a proper wound (chip or TH) type inductor as needed.Tim
Ferrite Beads in Digital Circuits - Page 1
Forum section: electronics / beginners

author: ZedRedLed
author_rank: Contributor
timestamp: March 29, 2018, 11:05:59 pm
content: Hi,I'm currently trying to repair a keyboard after a spillage, that is giving me pretty random crosstalk between keys.I noticed what appeared to be a potentially damaged ferrite bead on the pcb. This leads me to the question:What purpose do ferrite beads have in a digital circuit?I read that their main use is things like radio applications or other things involving high frequencies to avoid EMI. I also read that they are used when powering an analog and digital circuit from the same power source. This might be the case here, as the keyboard also has audio jacks, but this doesn't fit its location on the pcb.Would it be necessary to clean up the power source?And could a broken ferrite bead in a keyboard pcb lead to this kind of strange behaviour?In case it helps, I'll include a picture of the pcb with the ferrite bead marked in red, the circuitry from the audio jacks to the very left and the rest being hooked up to the LEDs and membranesThanks in advance!

author: Chris-IP5
author_rank: Contributor
timestamp: March 30, 2018, 04:28:30 am
content: I think like you the beads are often used to prevent EMI.So an electronic equipment designer might addferrite beads so that their product conforms to FCC standards.If the keyboard is attached by a cable to the computer that cable could act like a transmitting antenna.As for "crosstalk" theres no spill left on the PCB, key contacts or the legs of the ICs? And correct keyboard selected in Control Panel (or equivalent) ?Additional - is it a laptop keyboard?

author: ZedRedLed
author_rank: Contributor
timestamp: March 30, 2018, 08:31:34 am
content: It's not a laptop keyboard and I don't think there is any left. I cleaned everything with isopropyl alcohol and I even completely taped over buttons on the membrane that still ended up being pressedThe only other thing I can think of is that it might be related to the 8 diodes in the picture, all of which I had to replaced.

author: Teun
author_rank: Regular Contributor
timestamp: March 30, 2018, 09:20:16 am
content: The beads are likely used to clean up the DC-voltage. Since they filter out higher frequencies they dissipate the noise energy into heat.http://www.analog.com/en/analog-dialogue/articles/ferrite-beads-demystified.htmlYou can try to "bake" the silicon membrane to get out the oily substances.http://www.michaelshell.org/gadgetsandfixes/keypadsiliconeoil.html
Ferrite beads in modern surface mount products - Page 1
Forum section: electronics / beginners

author: Dave Turner
author_rank: Frequent Contributor
timestamp: November 28, 2018, 09:34:58 pm
content: Hi all gurus,With current emissivity rules and the almost universal use of surface mount componemts for modern designs; how are the issues once addressed by the addition of ferrite beads to a component's leg (amongst many other issues & solutions) dealt with on modern pcbs?In the days of point to point (and/or dead bug) construction this was 'black magic' to the majority of hobbyists (and many professionals), which generally required a 'suck it and see' approach.Interested to see any answers,Dave

author: dmills
author_rank: Super Contributor
timestamp: November 28, 2018, 10:01:46 pm
content: There are plenty of ferrite beads available as SMT packages if you really need them (Sometimes useful for IO immunity and cleaning up switchmode supply ringing).However with 4 layer boards not being the expense they once were you can usually throw a plane under your routing layer and minimise the loop area (and radiation) that way instead, modern logic being 2.5/1.8/1.5/1.2/1.0V does not hurt any either.Don't forget that to be a reasonable radiator the geometry has to be bigger then about 1/8th wave at whatever frequency matters, and SMT parts are usually rather small, this helps a lot.Regards, Dan.

author: Dave Turner
author_rank: Frequent Contributor
timestamp: November 28, 2018, 10:19:44 pm
content: DanUnderstood - less energy - less crap - it's still black magic!CheersDave

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 29, 2018, 06:24:03 am
content: It's only black magic if you can't solve polynomial roots!Tim

author: dmills
author_rank: Super Contributor
timestamp: November 29, 2018, 11:19:38 am
content: And these days we got computers for that!No magic, it is just that as the frequency rises it becomes ever more apparent that the DC rules apply at a point along the conductor, that a wire is a component too, and that you cannot ignore the parasitics.Regards, Dan.
Ferrite beads vs low-pass for noise filtering - Page 1
Forum section: electronics / beginners

author: JohnnyVoxel
author_rank: Newbie
timestamp: July 11, 2017, 11:52:51 pm
content: Hello,I have a system on a 24 VDC bus that I am trying to eliminate noise going to. An inverter on the bus is causing a periodic 41khz wave shown in the attachment. My first thought was installing a lowpass filter, but due to the high frequency I'm wondering if a simple ferrite bead would do the trick. Thanks for any insight.-Johnny

author: JohnnyVoxel
author_rank: Newbie
timestamp: July 11, 2017, 11:55:18 pm
content: Annnnd... I just realized I measured the wave wrong. My noob is showingShould read 62.5khz

author: floobydust
author_rank: Super Contributor
timestamp: July 12, 2017, 12:31:29 am
content: Ferrite beads have little inductance and at low frequencies <100kHz they don't do much.You can get some multi-turn ferrite beads, but you need more inductance, 10uH-1mH.I would add an LC lowpass filter with a resistor across the inductor to dampen it. Don't chose values near the 62.5kHz or its harmonics to avoid resonance.I have also used 1mH common-mode chokes on 24V vehicles, depending on the load current and the noise source, and if things don't need a direct ground.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: July 12, 2017, 12:34:01 am
content: yes, beads are orders of magnitude too low inductance to be effective at 60 kHzneed multiturn inductors and R, C to make a LP filter, or just R, C if your current draw isn't too high

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 12, 2017, 01:06:44 am
content: That's an awfully low frequency to be having a problem with. Most analog circuits will ride through that just fine, for example. Can you not simply...get better stuff?Tim

author: Zero999
author_rank: Super Contributor
timestamp: July 12, 2017, 08:02:38 am
content: Quote from: T3sl4co1l on July 12, 2017, 01:06:44 amI agree, it's unlikely it's a problem. He probably just put his 'scope on the +24V line, noticed the noise and worried about it causing interference.
Ferrite core ampere turns relation to secondary current - Page 1
Forum section: electronics / beginners

author: mercurial
author_rank: Regular Contributor
timestamp: April 26, 2023, 03:47:02 pm
content: Say I have a ferrite core with rating of 0.25T max flux density @ 1000 At/mand the core has a effective length of 0.1 mNow if I wind 10 turns of primary wire on it and give 10A into it.that would make it 10 * 10 * 0.1 = 10 At/m correct?Now if I wrap 100 turns of secondary on it and load the secondary to 1A.Will this field strength of 10At/m increase or decrease due to the loaded secondary.Does the field strength calculation for both primary and secondary coils need to be added up to get the effective field strength acting on the core/

author: m k
author_rank: Super Contributor
timestamp: May 06, 2023, 04:10:25 pm
content: Transformer is more than a single component.It's more like a black box where one side is in and one side is out.So if that is the case then both sides can't have equal signs.Field density is energy through area.Around the core there is only one area through what the energy goes.In electrical sense primary and secondary are also not connected, the other side is like a black box.So if field density is added both sides must give energy and neither can take it.One example is winding direction check.There you put AC voltage to one winding and connect one end of the other winding to one end of the first winding.The you measure the voltage from not connected ends.If voltage increases from what is put in the winding directions are the same.If voltage decreases the winding directions are the opposite.

author: Picuino
author_rank: Super Contributor
timestamp: May 06, 2023, 07:30:40 pm
content: I subscribe to the thread

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 06, 2023, 10:08:17 pm
content: Use dimensional analysis. You put 10 turns * 10A * 0.1m = 10 Atm.But you need At/m. Something is wrong.Divide by 0.1m --> 1000 At/m. Which will evidently give close to 0.25T, whatever that figure relates to.As mentioned, if you're using this as a transformer, you must sum primary and secondary amp-turns. The core ONLY sees the total ampere-turns!And that difference will in general be very small for a transformer. And is not defined by winding currents, but by applied voltage and frequency -- flux. So you don't need to know winding currents at all, but use the applied waveform instead. This makes calculating flux density of a transformer much easier in most applications.Tim

author: Picuino
author_rank: Super Contributor
timestamp: May 07, 2023, 08:51:10 am
content: Normally the magnetic flux density produced by the primary winding cancels out with the density produced by the secondary winding.But this is not the way to calculate a transformer.

author: Picuino
author_rank: Super Contributor
timestamp: May 07, 2023, 09:06:25 am
content: Some formulas you may find useful.https://www.eevblog.com/forum/beginners/magnetic-circuit-formulas/You must first calculate the reluctance of your core and then, from there, you can go on to calculate transformer or coil parameters.
Ferrite core saturation - Page 1
Forum section: electronics / beginners

author: strawberry
author_rank: Super Contributor
timestamp: June 07, 2018, 06:59:22 pm
content: how to measure saturation current and convert in Teslas and vise versa?

author: jmelson
author_rank: Super Contributor
timestamp: June 07, 2018, 07:16:47 pm
content: You have to know all the mechanical features of the inductor. So:number of turnspermeability of core materialsurface area the gap of any air gapcross sectional area of coreGiven this, you can calculate the average flux in the core for any current. Then, given the saturation flux, you can see where this intersects the current.Jon

author: jmelson
author_rank: Super Contributor
timestamp: June 07, 2018, 07:20:06 pm
content: Oh, the other way. Apply a constant voltage to the inductor with a transistor that turns on and off, and measure current with a series resistor. Observe voltage across resistor with an oscilloscope. You will get an approximately linear current ramp up to some point, then the current will start to rise faster. Roughly where the linear curves up is the point you can call saturation.Jon

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 07, 2018, 07:21:37 pm
content: You don't directly convert amperes to tesla.Instead, apply a pulse waveform, and measure the area of the pulse, from zero to the point of saturation. If a square pulse is used, the area is simply V(on) * t(on).tesla == V.s/m^2 == V.us / (mm)^2. Once you know the cross sectional area of the core (don't forget to divide V.s by number of turns), you have tesla.It's not very important though, as ferrites all saturate in the 0.2-0.4T range, and core loss typically limits operation to a fraction of that.Tim
FET driver IC's with two Vcc and two ground pins question - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: May 22, 2019, 11:38:50 am
content: Sorry, I am here again, don't worry, I will be back to work next weekI am implementing a pair of faster and more powerful FET drivers in a Class D MF RF Amp. The blurb shows different versions, some with one vcc and one ground and some with two of each. Is it vital to use both of the grounds and Vcc pins in the packages that have them, or are they there to give more flexible routing options please? The data sheet for them is linked below, it's too big to attach. Thanks. I want to use eitherIXDD614 PI / SI or IXDI614 PI / SI the difference one has an enable pin and one has not got one.http://www.chriswilson.tv/IXYS-IXDD614CI-datasheet.pdf

author: Psi
author_rank: Super Contributor
timestamp: May 22, 2019, 12:10:00 pm
content: Multiple pins should always be connected together externally, unless the datasheet explicitly says otherwise.I don't think i've ever seen a IC where it's ok to use the pins to make routing easier.With regard to fets, the extra pins are usually there to allow for higher current flow, and for better heat sinking ability.
FET leakage reduction | simulation troubles - Page 1
Forum section: electronics / beginners

author: juma98
author_rank: Contributor
timestamp: March 22, 2023, 02:35:34 pm
content: Hey everyone,I'm messing around with an opamp integration circuit with FETs to reset the integrator. The simulation behaves as expected until the capacitor value is in the pF range.Then it won't discharge entirely and the voltage, directly after discharge, increases if the capacitance decreases. Discharging for longer doesn't have an effect. I'm not sure why that happens. What am I overlooking? I've attached an image of the circuit and a few output waveforms for various values of C and I.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 22, 2023, 02:44:05 pm
content: The MOSFETs have a gate capacitance and part of the charge from the switch FET ends up at the integrator input.

author: juma98
author_rank: Contributor
timestamp: March 22, 2023, 03:45:20 pm
content: So I guess the only suitable option would be a reed relay to discharge the integration capacitor if it is in the pF region.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 22, 2023, 03:54:22 pm
content: A reed relay is possible, but with some timing uncertainty.For a FET switch one could compensate the gate charge with a small capacitor to an opposite sign voltage. Ready made CMOS switch chips usually already include such compensation - to a part from the combination of P and N channel FETs.
FET preamp without gate pull-up resistor never works - Page 1
Forum section: electronics / beginners

author: dusan
author_rank: Regular Contributor
timestamp: December 26, 2021, 08:43:27 am
content: When I search for "FET preamp", like here:https://www.google.com/search?q=fet+preamp&tbm=ischgood half of the schematics shows that there is no pull up resistor from gate to VDD, for example like the one in attachment.When I make these (in breadboard or in simulator), they never work. Which is kinda logical as FETs usually require some minimal gate voltage (around 1V similar to bjts). When I put pull up resistor (e.g. 3M pull up, 3M pull down which puts it to the middle of VDD) it start working.My question is, what am I missing here? Good half of the schematics shows no pull up. I've tried them all, they never work. Am I missing some crucial bit of information that prevents me from making them work? I just don't understand how half of the schematic can be wrong, so I assume they are correct and I'm doing it wrong. Thanks.Edit: I'm using BS170 (fet, N-Channel, Enhancement Mode, BS170)

author: Kleinstein
author_rank: Super Contributor
timestamp: December 26, 2021, 10:26:43 am
content: The circuit diagram shows a JFET. Essentially all JFETs are depeletion mode and they thus work OK in the linear region with zero gate votlage.The BS170 is a enhancement MOSFET and thus need some postive bias to work. If it needs to by a MOSFET, there are also depletion mode MOSFETs (like BSP135 ( Microchip also has a few in To92).

author: magic
author_rank: Super Contributor
timestamp: December 26, 2021, 10:36:13 am
content: Strictly, in this circuit they work with negative gate-source voltage because source is elevated above ground due to voltage drop across the source resistor. The value of that resistor regulates operating current (which also depends on characteristics of the transistor: Ic vs Vgs; different JFETs will yield different current with the same resistor).

author: BrokenYugo
author_rank: Super Contributor
timestamp: December 27, 2021, 05:40:47 pm
content: While people do make a habit of calling both "FET", MOSFETs and JFETs are not really interchangeable, if you search for a "FET preamp" you are going to mostly get JFET designs.You may find this presentation helpful in understanding how a JFET works and the differences from MOSFETs.

author: Terry Bites
author_rank: Super Contributor
timestamp: December 27, 2021, 05:44:22 pm
content: Why worry?
FETs connected the "wrong" way? - Page 1
Forum section: electronics / beginners

author: pplaninsky
author_rank: Regular Contributor
timestamp: January 12, 2022, 11:30:40 pm
content: Hi,I am looking at the block diagram of this power switch IC.I have two questions:1. The main switch P-MOS body is connected to ground. How does this work?2. The flag (FLG) driver is also a P-MOS with the body connected to ground. Isn't that supposed to be a N-MOS open drain?Thanks!https://www.richtek.com/assets/product_file/RT9742/DS9742-10.pdf

author: Cerebus
author_rank: Super Contributor
timestamp: January 13, 2022, 03:36:17 am
content: Your reading of what they should be seems entirely reasonable to me. I think I'd just assume that the graphic artist given the job of cleaning up the schematic for publication didn't understand what they were looking at, screwed up, and someone didn't check it properly.

author: Bud
author_rank: Super Contributor
timestamp: January 13, 2022, 05:56:15 am
content: It is in the datasheet you linked, read the datasheet.

author: Terry Bites
author_rank: Super Contributor
timestamp: January 13, 2022, 05:45:47 pm
content: Total graphics cockup I think. And a lack of oversight by the engineers.Or is it like the American Megatrands-no, not trends- folly. "Yes its a typo but we can't be bothered to fix it, so there." SeeAbsurd.

author: Bud
author_rank: Super Contributor
timestamp: January 13, 2022, 08:11:27 pm
content: Do not mislead the OP.Let me try again:It Is in the datasheet. Just read the datasheet.

author: langwadt
author_rank: Super Contributor
timestamp: January 13, 2022, 08:30:01 pm
content: the datasheet says N-channel and chargepump, the drawing just uses a weird fet symbol

author: RoGeorge
author_rank: Super Contributor
timestamp: January 13, 2022, 09:40:02 pm
content: The weird MOSFET symbol is explained in the datasheet linked in the OP, page 11 of 19.
Few components are "in stock" on Farnell in UK - Page 1
Forum section: electronics / beginners

author: ocset
author_rank: Super Contributor
timestamp: August 12, 2018, 02:57:32 pm
content: HelloDoes anyone know what’s going on with Farnell UK these days?Hardly anything is in stock. It wasn’t like this a decade ago. Even 100nF , 50V, X7R, 0603 ceramics weren’t available the other day…at least not in quantities of less than 50. This is ridiculous.We are trying to get components together to build a 60W offline led driver, but nothing is in stock.Digikey and Mouser is much better, but attracts a £15 shipping cost to UK, and my company won’t pay that. –Specially since the unit is merely a demo unit, since we can’t compete on price with the led drivers available from the huge electronics corporations such as Samsung, Osram, Philips etc etc.RS is just as bad.Are there any other vendors around? Our lack of availability to compete on price with led drivers from the major corporations means we have to play on a shoestring budget….all the time.

author: picandmix
author_rank: Frequent Contributor
timestamp: August 12, 2018, 03:56:09 pm
content: Just entered your parameters and plenty in stock x10 off...?

author: guymo
author_rank: Regular Contributor
timestamp: August 12, 2018, 05:37:48 pm
content: The issue with this particular part is that there's a global shortage of MLCC caps, so prices are getting a bit high and stock is somewhat short. It's not impossible to get the parts you need but a little pricier than it ought to be.

author: Jwillis
author_rank: Super Contributor
timestamp: August 12, 2018, 06:25:43 pm
content: Avnet just acquired Premier Farnell/Element 14 in July.So there is mostly going to be some adjustments.Could even mean some stock changes.Hard to say for sure.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 12, 2018, 07:49:05 pm
content: Quote from: treez on August 12, 2018, 02:57:32 pmWhat planet have you been on lately? - there is a major shortage of jellybean caps due to under-production and high demand for more profitable lines.QuoteOnly if you can't make up a £33 order.QuoteWell if your company won't invest £15 to get an R&D prototype going you may as well give up now.
Few parts without markings... - Page 1
Forum section: electronics / beginners

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 23, 2017, 12:32:39 am
content: Anyone know what these things are? Making a schematic and need to annotate what they are.

author: Andy Watson
author_rank: Super Contributor
timestamp: March 23, 2017, 01:05:40 am
content: Can't get to the bigger images.The first device could be any three terminal device - likely a transistor or diode(s). When faced with similar anonymous packages I usually draw a circle and work-out what it is when I have more of the schematic to look at. Additionally, if it has any markings and I have a hint at what it might be, it can sometimes be identified via a site such as this:http://www.marsport.org.uk/smd/mainframe.htmThe second component looks like a capacitor - you will have to measure it to find its value.The third component is probably a diode - possibly a zener.It would help immensely if you could post as much of the schematic as you can.

author: OpenCircuit
author_rank: Regular Contributor
timestamp: March 23, 2017, 01:15:52 am
content: Quote from: Andy Watson on March 23, 2017, 01:05:40 amThanks for the reply Andy. Here is what I have so far-click image then click the image again to really zoom in:https://postimg.cc/image/mhf7ap4gp/Here is my thread:https://www.eevblog.com/forum/repair/atx-power-supply-dead/

author: xrunner
author_rank: Super Contributor
timestamp: March 23, 2017, 01:17:17 am
content: Quote from: Andy Watson on March 23, 2017, 01:05:40 amYep I agree.
Few queries PIC18F4550, MPLABX - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: April 29, 2016, 04:35:14 pm
content: I am using PIC18F4550 with MPBALX IDE V2.26, Xc8 V1.32.1. Putting string in ROM/flash: I have lots of strings in my code. I want to put those in flash.When I use this "rom" keyword, error appears, but if I remove this keyword there is no error. But it places string in data ram, which I dont want. What is solution.Error:Code:rom const char table[] = "fggx";source/global.c:14: warning: (374) missing basic type; int assumedsource/global.c:14: error: (314) ";" expectednbproject/Makefile-default.mk:158: recipe for target 'build/default/production/source/global.p1' failedmake: Leaving directory 'D:/project/Project_51_ashokji/pic/codes/current_code/V6_lcd/njg.X'(908) exit status = 1make: *** [build/default/production/source/global.p1] Error 1make: *** [.build-conf] Error 2make: *** [.build-impl] Error 2nbproject/Makefile-default.mk:78: recipe for target '.build-conf' failedmake: Leaving directory 'D:/project/Project_51_ashokji/pic/codes/current_code/V6_lcd/njg.X'nbproject/Makefile-impl.mk:39: recipe for target '.build-impl' failedBUILD FAILED (exit value 2, total time: 508ms)Build successful:Code:const char table[] = "fggx";2. On successful build, code gives some warning. What is corrupted fast interrupt shadow registers?Code::: advisory: (1233) Employing 18F4550 errata work-arounds::: advisory: (1234) * Corrupted fast interrupt shadow registers:: warning: (1273) Omniscient Code Generation not available in Free mode3. PIC18F4550 datasheet "DS39632E", gives all registers associated with peripheral on last page of that peripheral.Timer0 on Page 131, Table 11-1, has list of register associated with it.It also mention TRISA & its bits 0-6.What is their use in it?4. I have sizeof various datatypes in compiler. Sizeof float & double comes out to be 3 bytes? What does 3 byte means, it should be 4 bytes.

author: JPortici
author_rank: Super Contributor
timestamp: April 29, 2016, 05:10:51 pm
content: first question: declaring those as constants will put them in program memory, period. If you're still not sure, check the xc8 user manual on how to put constants in romsecond question: check the errata document, located after the datasheet in the product page. that's what the compiler is telling you. you probably have extended instruction set active, which is bugged, or something simillar

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: April 30, 2016, 02:24:32 am
content: 1. In xc8, only const is to be used.2. It was workaround by xc8.3. Only RA4 is used. Datasheet have error because it didnt show other bits grey.4. compiler has option to use both 24 or 32 bit floats
Few questions about Rigol1054 use. - Page 1
Forum section: electronics / beginners

author: Tomer
author_rank: Regular Contributor
timestamp: February 11, 2019, 09:38:19 pm
content: Hello All and thank you for your help.I have 3 questions about Rigol1054 use that i can't find answers, i went over the manual few times with no luck* Please see attached pic.1) Is there a way to display only a specific measurement, for example the VPP. I can only choose between display all or none ?2) Can I clear that line or decide what will be the default readings for display ?. I find myself need to change it again and again to what i want.3) How to stop that from being displayed ?Thank you for your helpTom

author: mcinque
author_rank: Unknown
timestamp: February 11, 2019, 09:51:20 pm
content: 1) to show only a specific measurement use the left menu, choosing the measurement you want on the screen, this measurement will be "added" to the bottom bar on the screen; depending on the font size, you can have 4 or less measurements at the same time on the screen2) you can clear the line with the right menu "clear"3) if I understood correctly, you want to remove "measure all": you can do it using the right menu and pushing on "measure all"I suggest to watch some YouTube reviews and you will understand quickly many menu commands and functions of the scope.Hope it helps

author: Tomer
author_rank: Regular Contributor
timestamp: February 12, 2019, 09:34:41 am
content: Thank you for your help!Tom

author: metrologist
author_rank: Super Contributor
timestamp: February 12, 2019, 06:29:21 pm
content: this is a more clunky part of the interface so not surprised it's not intuitive.
FFT in MATLAB - Sequence Length? - Page 1
Forum section: electronics / beginners

author: norand
author_rank: Contributor
timestamp: January 10, 2020, 04:22:27 pm
content: Hi All,I have a question related to some DSP coursework for my degree (So try not to directly tell me if possible - but I really need to understand). My lecture has asked the following:"A discrete time sinusoidal signal can be generated in Matlab as follows:N = 0:1:100; f = 0.1; x = sin(2*pi* f*n);where f=0.1 is the normalised frequency of the sinusoidal waveform. Apply,stem(abs(fft(x))) and discuss the results.Now generate x as x = x = sin(2*pi* 0.1*n) + 3*sin(2*pi* 0.25*n). Obtain discreteFourier transform coeffects and discuss the results. "So from this, I get two DFT plots, and can make the following conclusions:The amplitude plotted is equal to the amplitude of the sin wave * N/2 (sequence length/2)The Frequency plot is mirrored around the N/2 pointThe DFT plot gives me multiple frequency points (rather than the 1 or for the second part 2 expectedI have noticed that if I change the sequence length to N = 0:1:(100-1), then the last point goes away, and hence the DFT plot only gives two Fourier coefficients as expected. This is obviously more correct than what my lecturer has provided, but I am struggling to see why it is making such a big difference.In conclusion, my question is why do I get more Fourier components with a sequence length of 101 or greater in comparison to 100? I have attached the two plots as JPEG format, and can provide code if necessary.Thanks in Advance, am happy to direct my question elsewhere, but you guys are always super helpful with my other electronics questions so thought I'd try here first.

author: gf
author_rank: Super Contributor
timestamp: January 10, 2020, 05:41:19 pm
content: Seehttps://en.wikipedia.org/wiki/Spectral_leakageandhttps://en.wikipedia.org/wiki/Window_function.

author: Andy Watson
author_rank: Super Contributor
timestamp: January 10, 2020, 06:00:38 pm
content: You might want to add to your list of conclusions by considering what determines the frequency resolution of your DFT, and then what happens to the energy in the frequencies that are not perfectly resoloved.

author: unitedatoms
author_rank: Frequent Contributor
timestamp: January 10, 2020, 06:31:03 pm
content: To understand it intuitively consider that with different sequence length you form different signal. Fourier treats signal as repeated fragment infinite times over.If at point of stitching the fragments you have a discontinuity, the spectrum will show it. Try to choose exact amount of samples to have perfect stitching. Or else you need to do a smooth magnitude shaping (windowing) to force stitching at zero magnitude.

author: norand
author_rank: Contributor
timestamp: January 10, 2020, 11:13:27 pm
content: Thanks all! Sometimes it's just knowing what to type in google - I found this TI video really explained this for me.TI Precision Labs – ADCs: Fast Fourier Transforms (FFTs) and Windowing:
FFT setting for harmonics on AC ? - Page 1
Forum section: electronics / beginners

author: SND
author_rank: Newbie
timestamp: June 26, 2019, 03:43:45 pm
content: Just wondering if you guys can point me in the right direction for maybe a tutorial video or such on properly setting FFT parameters. I searched youtube a bit and it helped some, but its not quite there yet for what I want it to display. I have a Siglent SDS-1104X-E and Micsig D20003P probes, set to 200X. Trying to probe for harmonics/noise 5khz or less down to 3rd harmonic if possible, on 60Hz AC circuit. Yes I do know all about the dangers of working on AC, not new to it.So far the settings I've tried are still showing too many lines that I don't believe mean anything useful yet and were not really changing with the system that I know to cause noise on the line turned on or off. Could the 200x attenuation make it harder for the scope/FFT to pick up these harmonics?I'd like it to just show a bar graph essentially of the highest noise peaks present on the circuit. From what I had read about these scopes and FFT ahead of time it sounded capable of what I'm trying to do, actually doing it so far is a bit trickier.thanks

author: rstofer
author_rank: Super Contributor
timestamp: June 26, 2019, 04:23:00 pm
content: It certainly doesn't seem like I can go to such low frequencies on my Rigol DS1054Z. Given that the lowest Hz/Div I can select is 5 kHz, I don't see where this is going to work out for low order harmonics and the higher order harmonics will generally have a 1/n relationship to the amplitude of the fundamental. For a perfect square wave, the 7th harmonic will have an amplitude of 1/7 the fundamental.Where I CAN do such low frequencies is with the Analog Discovery 2. In the attached display, I just put wire in one side of the CH1 differential inputs and touched it with my fingers. There's real science going on here!

author: Fludo
author_rank: Regular Contributor
timestamp: June 27, 2019, 05:01:45 pm
content: First I will say that low cost 8 bit scopes with the FFT option have never produced any meaningful harmonic data for me. I also have that MICSIG differential probe and the output was not clean enough to resolve small amplitude harmonics.
Fiber Optic / Optical Fiber Power Meter Tester - Page 1
Forum section: electronics / beginners

author: Electro Fan
author_rank: Super Contributor
timestamp: December 30, 2021, 07:18:57 pm
content: Anyone have a favorite fiber optic power meter?Mostly I'd like something that supports SC connectors and the APC (green) interface - and that can simultaneously show readings for 1310, 1490, and 1550 nm.Two that look interesting are:Komshine KPN-35https://www.komshine.com/test/pon_power_meter_kpn-35.htmlhttps://www.komshine.com/uploads/KPN-35_PON_Optical_Pwer_Meter.pdfQBL-PON106Ahttp://qblinnovations.com/meters/http://www.sh-stcomm.com/pro-info.html?product_id=133Any comments/suggestions/recommendations welcome. Thanks!

author: awallin
author_rank: Frequent Contributor
timestamp: December 30, 2021, 07:28:42 pm
content: I tried a dirt-cheap Multicomp from Farnell against a 'real' power meter from Thorlabs, results in my blog:Multicomphttps://fi.farnell.com/multicomp-pro/mp700121/optical-power-meter-hh-70-to-10dbm/dp/3267133?ost=mp700121Thorlabs PM20Chttps://www.thorlabs.com/thorproduct.cfm?partnumber=PM20C#ad-image-0some measurements:http://www.anderswallin.net/2021/01/fiber-optic-power-meter-test/the cheap meter only has a few wavelength settings, the Thorlabs meter has adjustable wavelength in 1nm steps. afaik the wavelength setting adjusts for the responsivity of the ingaas sensor, which varies with wavelength.for most work the 28 euro meter is fine!?

author: ve7xen
author_rank: Super Contributor
timestamp: December 30, 2021, 07:46:25 pm
content: "Industry standard" would be the Exfo EPM-50 series or Fluke SimpliFiber Pro OPM, though neither show multiple calibrated values at the same time (not sure why this is too useful - you do understand that the receiver is wideband and doesn't filter the light? Setting the lambda in the meter just changes the calibration coefficients assuming that all received light is that colour). The much cheaper meters from fs.com do seem to work alright, but I'm not sure about their calibration and wouldn't use them in a serious context.QuoteI suggest that you ignore the connector that is on the meter in your selection process. You want to avoid damaging the aperture or getting it dirty as it's not so easy to clean, so it's wise to leave your reference patch cord attached to the unit at all times, which can be more easily cleaned and replaced if the ferrule becomes damaged. FC is convenient for this as it has a more solid lock. Just get a reference patchcord with the appropriate connectors. Also the polish on the connector plugged into the power meter doesn't matter (PC/UPC/APC), since the sensor doesn't actually mate with the ferrule, it just collects all the light at the aperture.
Fibocom N510GL - Page 1
Forum section: electronics / beginners

author: Joki.I
author_rank: Newbie
timestamp: July 25, 2022, 02:18:38 pm
content: Hi everyone,I wanted to ask if anyone's got experience using Fibocoms N510GL modem. I found the Datasheet for the modem, but it was rather lacking, and there is no official AT commands manual (as given by ublox). Contacted Fibocom at least 5 times and got no response from them.If anyone's got some experience or advice to share, I'd love to learn more. They are rather cheap, and I only need them for LTE, NB-IoT.
Field-Oriented Control simulation is not working in Simulink - Page 1
Forum section: electronics / beginners

author: cadena
author_rank: Contributor
timestamp: August 01, 2020, 04:02:35 pm
content: Please ignore this topic and see "Issues trying to make my FOC simulation work". I am trying to remove this one but I can't

author: rstofer
author_rank: Super Contributor
timestamp: August 01, 2020, 11:18:45 pm
content: Have you posted this on one of the MATLAB forums?

author: somlioy
author_rank: Regular Contributor
timestamp: August 02, 2020, 08:21:49 am
content: Your input vector to the PhaseVolt input on the PMSM block is of size 6 while it is only supposed to be of size 3. Ie. This should be the three phase voltage vector (the stator terminal voltages). You should probably have used a "dq0 to abc" transformation instead.
Field strength measurement - Page 1
Forum section: electronics / beginners

author: kumar
author_rank: Contributor
timestamp: April 02, 2015, 12:31:07 pm
content: I have RF Explorer with it's standard antenna. RF Explorer shows received power in dBm and dBuV but not field strength in dBuV/m.This is to check the radiated emission from an electronic equipment. The power radiated by the equipment is unknown.The antenna supplied with RF explorer is un-caliberated Nagoya antenna. So can any one please tell me a practical way to find this?

author: w2aew
author_rank: Super Contributor
timestamp: April 02, 2015, 01:07:31 pm
content: You would need an antenna with known/calibrated frequency response (antenna factor vs. frequency), and then a means to import those antenna factors into the RF Explorer (if it has that feature), then make measurements at a specific distance, etc. There is a reason why emissions compliance measurements cost money - equipment and setup is expensive to do it accurately.
Figuring Out Bulb Specifications - Page 1
Forum section: electronics / beginners

author: PixieDust
author_rank: Frequent Contributor
timestamp: April 16, 2020, 02:19:06 pm
content: I purchased some incandescent light bulbs, but I can't find any information about them. I just know the voltage that they take but not the current or their wattage. Is there some way of figuring out how much current they can take without destructively testing them?

author: Manul
author_rank: Super Contributor
timestamp: April 16, 2020, 02:34:39 pm
content: For incandescent light bulbs voltage is everything you need. If you apply this voltage it will take as much current as it needs and no more. So you do not need to worry about that. You just need to be sure that the power source is capable of supplying this current. So for example if light bulb needs 100mA, you need to use power source which is capable of at least that or more. If you are interested in actual current and wattage, you can measure how much current it takes with a multimeter.
Figuring out wattage of Weller soldering station transformer - Page 1
Forum section: electronics / beginners

author: BinaryBits
author_rank: Contributor
timestamp: July 18, 2022, 08:54:52 pm
content: I ask the question first for those who don't want to read about the reason for my question....is there some way to figure out the wattage of the transformer if I only know the voltages, but not the Amps or the VA rating?So I have the soldering station Weller WD1M, and it has been made in both 95W and 160W versions. The 160W version can drive soldering irons up to 150W. I don't want to buy the 150W iron unless I know if it will work with my station.My station has a sticker that says 95W, but the transformer inside my unit is not the one used in the 95W version (58748740), but its also not the usual transformer normally used in the 160W version (58758725).My unit has the motherboard number thats used on the newer 160W version stations.My transformer has the number 58758030, and only says "Weller 230/23.5/11.5" on the transformer sticker.The voltages also seems strange, they are usually 24V and 12V on Weller transformers. I only found one mentioning online about this number, it was on a certification document for the WD1M, WD2 and WD2M, and that document mentions the wattage as 160W and the transformer number as 58758030 (same number as on mine). But nothing else comes up on the internet for this number.So this seems to be a Weller transformer thats not normally used in the WD1M, or in any other Weller products?Im also pretty sure the 95W and 160W transformers has the same size and looks the same, so that isn't a clue.Thanks in advance.
Figuring out what a sensing cirquit in an EDM Spark generator does - Page 1
Forum section: electronics / beginners

author: KOR
author_rank: Newbie
timestamp: October 31, 2021, 12:12:50 pm
content: I got the schematic of the attached sensing cirquit. I know that from Vout+ high current pulses with multiple kHz frequencys are comming the connector is a bnc connector.But overall my limited knowledge about electronics just can't figure out why a high pulsing current path is cut open and a tiny 0805 1k resistor is put in its way. The PCB trace which is blocked by the resistor is 60 mil.Sry I don't have much more information other than it is a sensing cirquit of a EDM spark generator.Thank you for your help.

author: jmelson
author_rank: Super Contributor
timestamp: November 01, 2021, 01:34:34 am
content: There is most likely a heavy-duty low-value resistor across R34 that actually measures the current through the electrode. The 1 K SMT resistor is likely there to do something sensible if the wires to the current sense resistor go open.Jon

author: KOR
author_rank: Newbie
timestamp: November 05, 2021, 06:21:45 pm
content: after checking all the traces and finding none I measured the little bugger it is 0.1Ohm. (Silkscreen says 1k) So I guess it is a current sensing resistor. It still seems to me pretty high in value since such a tiny resistor can't be more than 0.5W which would be 2.2A at most. Ok it is a pulsed current so one could probably drive it with a higher current but still it seems way to weak.I am still completly confused what this cirquit actually does. Is there a way to simulate the cirquit So I can find out what is actually happening? Or can someone explain it to me like I am a five year old

author: SeanB
author_rank: Super Contributor
timestamp: November 05, 2021, 07:49:18 pm
content: Current sensing on the high side, the transistors are there to make a current mirror, turning the voltage drop across the sense resistor R34 into a current, which is converted to a voltage proportional to the current in R37. the capacitor is there to filter out noise, and the current generated is, to a large part, independant of the actual applied voltage, so the measured value is current only.

author: jmelson
author_rank: Super Contributor
timestamp: November 05, 2021, 08:02:47 pm
content: Quote from: KOR on November 05, 2021, 06:21:45 pmMeasuring low-value resistors is very hard. Most meters are good to +/- a couple Ohms at best.And, in-circuit, even less accurate.Is this wire EDM or sinker? Wire EDM runs at much lower current.Jon

author: KOR
author_rank: Newbie
timestamp: November 07, 2021, 06:50:06 pm
content: Thank you guys. I know that it is hard to measure low values of resistance thats why i desoldered the resistor.@jon: it is a sinker.
figuring out what this little board does - Page 1
Forum section: electronics / beginners

author: kenn
author_rank: Contributor
timestamp: December 29, 2017, 06:51:41 pm
content: so I am trying to figure out what this little board is - I have attached a photo - I figured out that the center terminal is ground and that pin 6 connects directly to the terminal with C2 labeled on it (that for the cap I know but it's printed right on the trace) but I can't figure out what it does, the chip has the marking LTNC I think although it's got some crust on on it and it's super hard to read. At any rate I put five volts to it and measured the third terminal and it was five volts as well, switching the jumper around didn't seem to do anything and changing the pots didn't do anything either so I think it's maybe some sort of current regulator? That's the best I could do with my limited skill set so hopefully someone can tell me what this is.Thanks!

author: JoeN
author_rank: Frequent Contributor
timestamp: December 29, 2017, 10:16:33 pm
content: I don't think this is right, but...List of Linear markings:https://cds.linear.com/docs/en/packaging/Linear_Technology_Top_Markings.pdfLTNC maps to LT1616 - 600mA, 1.4MHz Step-Down Switching Regulator in SOT-23http://www.linear.com/product/LT1616https://cds.linear.com/docs/en/datasheet/lt1616fs.pdfThat IC looks like a SOT-23, but it looks like it only has 5 pins and the LT1616 has 6.Maybe check that IC again under a strong light and magnifier for the code?
Files WFM - Page 1
Forum section: electronics / beginners

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: April 29, 2018, 10:55:43 pm
content: hello, I have several files with WFM extenders that record with the rigol DS1054z. With what PC software can I open them?

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 15, 2018, 05:57:49 pm
content: maybe tryVisaDSO