hybridfree/eevblog-posts huggingface dataset:
Cable tester upgrade - Page 1
Forum section: electronics / projects

author: negativ3
author_rank: Regular Contributor
timestamp: September 12, 2016, 12:38:56 pm
content: Hi all,I have been using the cable tester as per the schematic attached for many years, without issues. It shows if a core is well connected, poorly connected or if there are crosses and/or shorts.It can be reconfigured to suit any configuration of cable with current handling of nominal 0.7A.My question is, could I replace the DPNO switches with transistors? I would like to enable an automatic test routine then provide user feedback as to pass/fail via a uC.ThanksAndy

author: Messtechniker
author_rank: Frequent Contributor
timestamp: September 12, 2016, 01:52:35 pm
content: I'd replace the switches with microprocessor driven relays.Yours Messtechniker

author: bicc1306
author_rank: Contributor
timestamp: September 29, 2016, 12:49:32 pm
content: Yes, you can replace the DPNO switches with transistors. see below discussion.http://electronics.stackexchange.com/questions/38867/replacing-a-switch-with-a-transistor
Cable type for LVDS signals - Page 1
Forum section: electronics / projects

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: February 17, 2016, 11:39:13 pm
content: I'm trying to route a number of LVDS signals (5 ns edge rates), and made up a cable with 3M 3600X series 12-pair cable. Digi-key lets you buy cut lengths of this, which is a huge benefit for low-volume/prototyping stuff that I tend to do. I noticed (AFTER I bought it... argh!) that the 3600X cable is listed as having 91 ohm differential impedance, instead of ~100 ohm required by LVDS.My question: for short cable runs (about 50 cm), will this make a difference?The connectors used on either end are Tyco HD-22 series 26-pin connectors (similar to VGA monitor connectors)Thanks

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 17, 2016, 11:56:25 pm
content: The SATA cables are specified at $$100\mho \pm 10 \%$$sedit: damn Mathjax

author: wraper
author_rank: Unknown
timestamp: February 18, 2016, 12:05:27 am
content: 91 ohm is within allowed tolerance.

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: February 18, 2016, 06:53:55 am
content: Thanks, all. The cable appears to work, I'm just a bit wary of stuff breaking down the road.

author: AndyC_772
author_rank: Super Contributor
timestamp: February 18, 2016, 07:35:13 am
content: Unless I'm very much mistaken, those connectors are not impedance controlled. If you have an SI issue, it wont' be because of the cable.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 18, 2016, 06:54:28 pm
content: With a 5ns edge rate and that length, you will hardly need termination at all!Tim

author: retrolefty
author_rank: Super Contributor
timestamp: February 19, 2016, 02:06:33 am
content: If not working with 50 ohm terminal loads, would using 72 ohm cable matter when just using the normal 1 meg ohm input impedance of the scope?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 19, 2016, 06:00:07 am
content: For probing? If you aren't terminated at the load (scope) end, then you need to be terminated at the source (probe) end. If the node being probed doesn't have a matched impedance, you will see effects near the characteristic frequency of the cable.Tim
Best Cable Gland manufacturer for Oil, Gas and petrochemical industry? - Page 1
Forum section: electronics / projects

author: bicc1306
author_rank: Contributor
timestamp: August 23, 2016, 05:37:29 am
content: Which are the best cable gland types or materials and manufacturer for Oil & gas, petrochemical and railway industry?Thanks in advance.

author: Blastcap
author_rank: Regular Contributor
timestamp: August 23, 2016, 09:08:53 am
content: Icotek has a bunch of more or less complicated EX rated cable entry solutions.http://www.icotek.com/en/We have used them for railway applications without problems.

author: Delta
author_rank: Super Contributor
timestamp: August 23, 2016, 11:26:15 am
content: Hawke.De facto standard in UK oil and gas. Good stuff.

author: bicc1306
author_rank: Contributor
timestamp: August 24, 2016, 06:53:31 am
content: Thanks for your reply @Blastcap and @Delta.Do anyone had experience about this:http://bicccomponents.uk.com/How is BICC components?Shoul I go for BICC or De Fecto?

author: Blastcap
author_rank: Regular Contributor
timestamp: August 24, 2016, 07:10:21 am
content: BICC seems to be uncoated brass, I'm not sure they are suitable for Oil and Gas environments (Ex).Better you just shoot them an E-mail with a description of your task and talk to the manufactures directly, they can probably help you navigate their product lineup, and find the best one for the task.

author: Delta
author_rank: Super Contributor
timestamp: August 24, 2016, 10:49:39 am
content: BICC's CW compression glands are not Ex certified, and thus not suitable for use in hazardous areas. Stick will Hawke. You can now get quadruple certified CW glands from Hawke, so aside from barrier glands on Ex d enclosures, your sparkies simply cannot pick the wrong gland from stores!PS. The cynic in my wonders why you appear on here asking about BICC produces, with a username such as yours....
Cabling Solution for Analog Differential Line  - Page 1
Forum section: electronics / projects

author: zdavis92
author_rank: Newbie
timestamp: July 20, 2021, 04:50:34 pm
content: Hi Al (first post on this site!)I'm designing a system with 2 different PCBs. First PCB has a THS4140 used to convert a single-ended analog signal to a differential signal. Second PCB has an ADC with differential input This differential signal needs to find its way to an ADC on the second board, via some sort of cable. I included a reference snapshot, in attachments, from the datasheet of the THS4140 in case you want a better visualization.I was wondering if you had suggestions on which cabling solution might fit my needs? Was thinking some sort of twinax or twisted pair, but not sure if anyone has any better suggestions.All input appreciated. Thanks!

author: zdavis92
author_rank: Newbie
timestamp: July 20, 2021, 06:02:35 pm
content: Thanks for reply.The bandwidth is pretty low, below 80 MHz. Most worried about EMI radiating from digital electronics inside the contraption this will be in (will be inside a piece of test equipment). The analog line comes from a low level analog sensor used to take very sensitive measurements, so we are primarily focused on shielding these lines from any noise. Primarily chose differential mode of transmission to suppress any common mode noise picked up on cable. The distance it's going over is about 1 meter, so was hoping to use a shielded twisted pair or shielded differential transmission line. Do you think just using standard SMA/BNC and single ended would work for this?

author: David Hess
author_rank: Super Contributor
timestamp: July 20, 2021, 06:21:24 pm
content: 4 wire ribbon cable with the two outside wires being ground will also work.An inexpensive solution if you want shielded cable is microphone cable. Twisted pair with a foil shield and drain is also available.
Cadence beginner question/problem?! - Page 1
Forum section: electronics / projects

author: Jolle
author_rank: Contributor
timestamp: November 05, 2014, 12:54:52 pm
content: I am currently doing a project at my university where I have to use cadence for some layout of integrated inductors. In order to get familiar with the program I have followed some tutorials where a nmos transistor is simulated, but I have encountered a problem while trying to simulate the mosfet. The schematic and the problem can be seen in the link below.https://www.dropbox.com/s/2a1ks6ixrirham2/substrate%20problem.png?dl=0I have used a 4 pin nmos from the technology used by my university, but when I try to simulate I get the warning "Failed to resolve inherited connections on instance 'M0' in cellview. This is because the netset property "substrate" on this instance refers to a signal 'sub!', which is not present in the cellview". As can be seen in the link.Does anybody know how this is fixed in the correct way?If I connect the body to gnd through a 1m resistor and call this node "sub!" the program will let me run a simulation, and give me a results which is as I expected, but I am pretty sure this is not the correct way to do it.

author: RobinF
author_rank: Newbie
timestamp: November 05, 2014, 01:58:43 pm
content: No, that is in fact the correct wayThey use a global node named "sub!" so that all substrate nodes are always connected together. You only have to make a connection to that node on the top level of your design, as you have done. Except you should connect it with a low impedance, i.e. a zero-volt voltage source rather than a 1 M resistor.
Cadence Virtuoso Question  - Page 1
Forum section: electronics / projects

author: jnestor481
author_rank: Newbie
timestamp: March 01, 2021, 06:07:07 am
content: Hello all,Hope this isn't the wrong place for this type of question, regarding cadence virtuoso. So I recieved files that were generated on IC5033, and I have IC6.1.6 so I'm trying to convert them with the translator tool. But I'm not understanding the error messages it's giving me. I placed the schematic in a library of it's own and outside of the folder where cds.lib file is. When I go to select that library it doesn't let me, saying "The cds.lib file specified does not exist or the file is not readable". OK. So I put it in the folder where the cds.lib file is and it tells me:ERROR (CDBOA-107): You cannot run the translator in the same directory as theCDBA cds.lib file. Doing so would add OpenAccess librarydefinitions to the CDBA cds.lib file, which is notpermitted. Run the translator from a different directory.Just an FYI, the contents of my schematic folder have the following extensions: .tag, .db , .xx , .cd% , cdbSo I just don't understand how I'm supposed to do this. I realize this is retard tier stuff, so any help would be much appreciated.

author: evac
author_rank: Contributor
timestamp: March 03, 2021, 09:22:20 am
content: The translator expects you to have an existing OA cds.lib file in the project directory where you want to import the CDBA to.It cannot run with a cds.lib which has CDBA entries, it's either all OA (IC6) or CDBA (IC5).Just run the translator in an existing project, or if you really need to run it in a clean directory, just create a dummy (i.e. empty) cds.lib file in an empty directory.
CadSoft EAGLE Help - Page 1
Forum section: electronics / projects

author: sweekly
author_rank: Newbie
timestamp: December 26, 2014, 04:57:41 am
content: Hey guys, I'm designing a PCB in EAGLE and I have a few pots that aren't going to be on the actual PCB, but instead nearby and connected to the board via wires. How can I keep these pots in the schematic for BOM and building purposes, but on the actual board layout not have them included and just have a hole that i can solder wires into? So far I haven't found a way to disconnect the board footprint from the parts in a manner that allows me to just place solder points for the wires. Thanks for the help!

author: Maxlor
author_rank: Frequent Contributor
timestamp: December 26, 2014, 05:16:46 am
content: Create a custom footprint/part that only includes the two pads you need.

author: sweekly
author_rank: Newbie
timestamp: December 26, 2014, 05:36:00 am
content: That's an idea, however is there a way so that I can place the 3 connectors of the multiple pots in any order, so that the PCB will lay out nicer, as it doesn't matter which order that pins are laid out if I'm wiring them in.

author: zapta
author_rank: Super Contributor
timestamp: December 26, 2014, 05:55:02 am
content: Quote from: sweekly on December 26, 2014, 05:36:00 amYes, when you attache the past to the footprint do it once for each unique order you need. I would do a consistent order though to avoid confusion.

author: prasimix
author_rank: Unknown
timestamp: December 26, 2014, 08:28:13 am
content: I presume that you need something what is in the attachment ...

author: Unknown
author_rank: Unknown
timestamp: December 26, 2014, 10:53:15 am
content: The standard "wirepad" library, and dummy the component connections by placing the wirepad pads close to (but not touching) the component?(Knowing Eagle, wirepad pads probably appear in the BoM...)Personally I just use 3 pin 0.1" headers & sockets, then manually strike them from the BoM later.

author: LukeW
author_rank: Frequent Contributor
timestamp: December 27, 2014, 11:28:20 am
content: Quote from: Tac Eht Xilef on December 26, 2014, 10:53:15 amYeah, a component is a component, you know.
Calculate Ferrite core losses vs data in the datasheet.What is the right number? - Page 1
Forum section: electronics / projects

author: Miyuki
author_rank: Frequent Contributor
timestamp: May 05, 2022, 09:03:29 am
content: Hi folks.I have a question about numbers in ferrite core datasheets.For example when I takeFerroxcube ETD54 corewhat have Ve 35500 mm³And3C95 Materialwith PV290 kW/m³When I put it together, it should be around 10.3 W losesBut the datasheet says "up to 17.000 W/set"Do they use different numbers to calculate core losses or add some huge safety margin?All manufacturers have similar ratio, for example, with CF139 it is 13.3W vs 21W

author: Wolfram
author_rank: Frequent Contributor
timestamp: May 05, 2022, 11:53:58 am
content: The first document gives typical losses, likely measured on small toroid with a uniform field distribution. The second document gives the maximum loss for a core with a less uniform field distribution (given the sharp corners of the ETD54 shape), so I think both could be correct, between the differences in geometry and typical vs. maximum.
Calculate Instantaneous Transformer Core Magnetic Flux Density B in LTSpice - Page 1
Forum section: electronics / projects

author: Etesla
author_rank: Regular Contributor
timestamp: February 18, 2024, 08:21:16 pm
content: Hi allI'm relatively new to transformers and transformer design. I like the approach of characterizing them and modeling them in a simulator like LTSpice because then I'm dealing with components I have good intuition about.Say my starting point is the method of characterization outlined in this video:https://youtu.be/muUwe8X51oY?feature=sharedand I have a model of the transformer I want to work with that looks as you would expect (attached image)I don't care about thermals yet, so I see my next limitation as saturation of the transformer core. I want to calculate the instantaneous magnetic flux density B in the transformer for any arbitrary method of driving it. I want to calculate B in tesla in a behavioral voltage source so that I can plot it in real time. I'm thinking B will be a function of some of the currents and some constants.Questions:1.) Is the model structure shown complete enough to allow for this calculation?2.) What information do I need to know about my transformer to complete the calculation of B? (stuff like Ae, Al, Number of turns???)3.) What is the calculation in terms of currents through components (or voltages, or derivates of signals, or whatever) and the constants in (2)?4.) If I had an approximation of the BH curve for my transformers core material, is there a way I could incorporate that information into the simulation? Like what does saturation look like? Changing inductances? Added resistors to represent now significant losses?
Calculate Measurement Error - Page 1
Forum section: electronics / projects

author: ludzinc
author_rank: Unknown
timestamp: April 05, 2016, 06:25:45 am
content: This is a question that I got wrong 20 years ago in my Uni Physics days, and I still don't know how to get it right....Assume I'm measuring the results of an experiment and I need to take three different measures (assume length, weight and temperature).If my length measurement has an error (accuracy) of 1%, my weight measurement has an error of 2% and my temperature measurement has an error of 5%, what is the overall error of my system?Do I just sum the percentages? (HINT: No, I did that and failed, and I never learnt why....)Thanks all.

author: zlymex
author_rank: Frequent Contributor
timestamp: April 05, 2016, 06:36:49 am
content: Normally in a RSS(root-sum-square) way if these three variables are all directly related to the final result.overall error = sqrt(1%^2+2%^2+5%^2)=5.5%

author: Krampmeier
author_rank: Regular Contributor
timestamp: April 05, 2016, 08:44:34 am
content: @zlymex: Correct, that is how measurement uncertainties are usually added. That is, if all the errors are uncorrelated. It also depends onhowthe system processes the individual values (add/substract or multiply/divide/power/...).@ludzinc: You may want to start readinghttps://www.wmo.int/pages/prog/gcos/documents/gruanmanuals/UK_NPL/mgpg11.pdfat chapter 7.2 or, if you really do like formulas, check chapter 5 ofhttp://www.bipm.org/utils/common/documents/jcgm/JCGM_100_2008_E.pdf.

author: ludzinc
author_rank: Unknown
timestamp: April 05, 2016, 10:52:44 am
content: Thanks!I can see I have some light reading at bed time tonight
Calculate power in rise and fall of switch mosfet PWM  - Page 1
Forum section: electronics / projects

author: AllTheGearNoIdea
author_rank: Unknown
timestamp: December 03, 2020, 02:46:19 pm
content: Hi I am hoping someone can give me some advice on how to measure or estimate the power being dissipated in a MOSFET being used to control speed a spindle motor or my mini CNC machine. It’s a low side driver, and the motor is around 2 amps at 24 volts off load. Im driving the mosfet with a pulse width modulated signal at 8khz the rise time and fall time is around 600us. The bit I’m not sure about is how to go about calculating the dynamic power. I don’t think I’m that interested in the power dissipation during the on time as RDs On is low for this mosfet at 0.04 ohms. I have a good selection of test gear etc.The background story is I have designed and built a spindle driver and for my own interest I would like to calculate the power dissipation within my mosfet. It runs total cold. I just need some help with the math please. I did make a video on this but wouldn’t recommend it as an hour of your life is a precious thing LOL but it shows the circuit and explain what I am doinghttps://youtu.be/3fFVMd66VIYBut thanks for any advice regard Chris

author: fourtytwo42
author_rank: Super Contributor
timestamp: December 04, 2020, 09:55:23 am
content: Hi ChrisFirstly I assume your 600uS may in fact be 600nS as your total period is only 125uS. Switching losses depend a lot on the nature of the load, inductive vs resistive for instance, assuming the former (motor) there is normally little current at turn on except the reverse recovery of any diodes in the circuit. The biggest switching loss is usually turn off where the peak on time current is being interrupted rather slowly. It is possible to calculate a probable loss but if you are able to measure current on an oscilloscope so much the better to see what is actually going on, or make a model in LTspice.BTW how did you arrive at the 600uS/nS figure, is that a measurement ?Regards42

author: trobbins
author_rank: Frequent Contributor
timestamp: December 04, 2020, 11:01:29 am
content: As 42 indicates, if you have the test gear, then I recommend you acquire the FET drain current and voltage waveforms, with sufficient resolution about the switching transitions. One crude method is to then calculate Pd = Vd x Id for small sections of that waveform, and then sum them up over one cycle, then multiply by the frequency to determine a constant power dissipation. That may be easier for you than setting up a simulation, and then aligning the simulation waveforms to your measured waveforms, and getting the software to do that integration. If you post some sections of the waveform then the forum can assist. Some waveform sections within a cycle will have a relatively constant dissipation, such as when the FET is fully on and fully off, and so are easy to calculate.
Calculating average current draw over time - Page 1
Forum section: electronics / projects

author: MrAureliusR
author_rank: Unknown
timestamp: July 28, 2014, 12:29:18 am
content: I feel silly that I don't know this, but after quite a bit of Googling and searching the forum, I haven't been able to find the correct formula or steps needed to calculate the average current of a project.I have a microcontroller which draws 4uA in Hibernate mode. It stays in this mode for almost the whole time. Every minute, it wakes up and measures a sensor, which takes about 100 milliseconds. During this time it draws about 5mA. Then it goes back into hibernation. Every 15 minutes, it wakes up, takes the past 15 measurements, and connects to the internet to upload them. During this stage, it draws about 180mA for about 3 seconds.My question is, how do I calculate the average current? This project will be running off of a 1200mAh battery and I'm curious to do some calculations.Is it as simple as adding up all the instantaneous currents and dividing by the number of minutes? That feels really wrong to me, it must be more complex than that.Any and all help would be much appreciated! It could be as simple as I'm not Googling the correct search terms, but I've been trying to find "calculate average current" and "average current draw" but it usually directs me to RMS calculations, which are not what I'm looking for.Edit: after a bit more searching... is it as simple as4uA + ((12/3600) * 180mA) + ((6/3600) * 5mA)Then take that result and divide by 1200mAh to figure out the time?

author: dannyf
author_rank: Super Contributor
timestamp: July 28, 2014, 12:40:35 am
content: Rough estimate - you can refine it further:Quote- 4ua * 15minutes = 0.06ma-minute;Quote- 5ma * 100ms * 15 times = 0.125ma-minute;Quote- 180ma * 3 seconds * 1 times = 9ma-minute.Total = 9.131ma-minute for every 15 minutes -> 0.6ma average drawYour battery, ignoring self-discharging and other errors, will last 1200mah/0.6ma = 2000hours.or its whereabouts.

author: MrAureliusR
author_rank: Unknown
timestamp: July 28, 2014, 12:42:44 am
content: Quote from: dannyf on July 28, 2014, 12:40:35 amThat's funny, right as you posted your reply I calculated 1972 hours....Guess I figured it out?Edit:The 4uA is essentially continuous, so I just added it as a continuous draw

author: IanB
author_rank: Super Contributor
timestamp: July 28, 2014, 01:06:36 am
content: I think you got there, but it's basically a weighted average:current x time + current x time + current x time + ...average current = ------------------------------------------------------------------total timeYou do this calculation over one complete cycle.

author: MrAureliusR
author_rank: Unknown
timestamp: July 28, 2014, 01:08:17 am
content: Quote from: IanB on July 28, 2014, 01:06:36 amThat's what I had in my head. You then take the capacity of the battery in mAh and divide by the mA average current. I had to remember to keep all my units relative to either mA or A, or else you throw everything off. It's easiest to do everything in mA because of the way battery capacity is measured.Thanks all for the info!
Calculating effect of components on coplanar waveguide on PCB? - Page 1
Forum section: electronics / projects

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 01, 2023, 01:40:50 am
content: I've started dabbling in some slightly higher frequency stuff than I am used to (up to around 3GHz) and I started thinking about the effects of components in coplanar waveguides.Take for example a straight trace on a PCB, with dimensions calculated to 50ohms impedance.I do things like using a 1206 part on a 1.6mm wide trace with 1.6mm wide pads to minimise size mismatch, mounting resistors upside down to keep the distance to the lower ground plane as close as optimum as possible, etc.Then I got to thinking, what about the effects of the ceramic in the resistor itself? Surely that will have an effect? Or is is negligible with the upside down mounted resistor?Is there a (simplified) calculation or a 'rule of thumb' to account for the resistor ceramic etc? About the only variable that is easily changed to maintain trace impedance is the clearance from the trace and component to the top ground plane, which is easy to fiddle with in the PCB software.If there is an easy way to calculate the required clearance from the component to the top ground plane for a given component substrate material?
Calculating interwinding capacitance of inductor - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: August 11, 2017, 08:01:34 am
content: We wish to use Power inductors for filtering SMPS. We want them to have as little interwinding capacitance as possible because we want to maximally impede the high frequency common mode noise from getting through this stray capacitance.As you know, interwinding capacitance is not listed in inductor datasheets, so please could you confirm that the “Self Resonant Frequency” is what we need to use to calculate this stray capacitance?Thats is, w = 1/[(sqrt(LC)]Therefore C = 1/(w^2 * L)

author: PChi
author_rank: Frequent Contributor
timestamp: August 11, 2017, 09:58:38 am
content: It looks OK to me but it is treating the interwinding capacitance as one element rather than distributed with the inductance so it's not an exact model.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 11, 2017, 10:49:43 am
content: Your formula should work correctly.Make also some measurements at below and above resonance and see that you get the same value for C. I always also use my LCR meter and force it in to C-Measurement. If your stray capacitance is of good value, depending on your LCR meter and measurement frequency, you can get a good and stable reading.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 13, 2017, 03:19:53 pm
content: This is a modeling problem:The "capacitance" is not a true capacitor, but a distributed (transmission line) effect.We can construct a model which approximates it, but which is not physically representative.To that end, the most accurate models I know of are by Coilcraft. This page gives an explanation of their model design, a viewer, and a way to rewrite their models for use in all SPICE simulations.https://www.seventransistorlabs.com/Calc/Coilcraft1.htmlCoilcraft's SPICE page is linked, where you will find parameters for most of their parts. If you are looking at another brand, it may be close enough to look for a Coilcraft cross-reference.Downside: most of the models stop abruptly after (and sometimes before) the self resonant frequency. Therefore, we should suppose that these models are not very accurate above the SRF, and the capacitance given is only a fit for that range, not a physical value.In practice, there will be numerous dips and peaks (series and parallel resonances) above the first SRF, depending on the exact placement and number of turns in the part. These features cannot be represented with the above model.Tim
Calculating RPM from BEMF frequency of BLDC motor - Page 1
Forum section: electronics / projects

author: Tomsik
author_rank: Contributor
timestamp: May 24, 2019, 07:30:23 am
content: Hello,I'm a beginner in driving motors and I need to calculate RPM (rotation speed) from frequency BEMF signal on 1-phase of a 12N14P motor when it'is possible.I measured 1.6kHz repeating signal (sinus) at 1-phase of BLDC motor.Can I calculate RPM from these parameters?Thank you

author: mikerj
author_rank: Super Contributor
timestamp: May 24, 2019, 11:07:55 am
content: You would need to know the number of poles in the motor to derive RPM from that figure.

author: mzzj
author_rank: Super Contributor
timestamp: May 24, 2019, 11:34:44 am
content: https://www.rcgroups.com/forums/showthread.php?2779762-How-many-poles-on-a-motor

author: Tomsik
author_rank: Contributor
timestamp: May 24, 2019, 03:43:27 pm
content: According to the shared thread I think I have 12 poles of stator, it means 6 pair poles.

author: Tomsik
author_rank: Contributor
timestamp: May 27, 2019, 07:11:31 am
content: Please help me

author: janoc
author_rank: Super Contributor
timestamp: May 27, 2019, 08:06:07 am
content: It is explained in that rcgroups article - the number of poles corresponds to the number of voltage cycles per rotation (logical, the voltage changes as many times as many magnets pass in front of the coil).So take the double of measured frequency, divide by the number of poles and multiply by 60 to get RPM value. However, this is going to be a fairly noisy value, depending on how exactly are you measuring the BEMF.BTW, you need to count poles of rotor (magnets!) not the stator poles. 12N14P is a 14 pole motor (the number before the P - again, did you read that rcgroups posting? 12N - 12 stator windings, 14 magnets), so:2*1600/14 * 60 = 13714 rpm, if I am calculating it correctly.

author: Tomsik
author_rank: Contributor
timestamp: May 27, 2019, 10:11:06 am
content: Thank you for answer.Why do you multiply RPM by two?

author: janoc
author_rank: Super Contributor
timestamp: May 28, 2019, 01:02:47 pm
content: Quote from: Tomsik on May 27, 2019, 10:11:06 amI think that has to do with the fact that each magnet passes over the coil you are using to sense the BEMF twice during each rotation (once over each "end").
Calculating speed-torque curve for stepper motor - Page 1
Forum section: electronics / projects

author: Emil
author_rank: Regular Contributor
timestamp: April 30, 2015, 11:43:41 am
content: I'm making a spreadsheet to estimate speed-torque curves for stepper motors when used with a current limiting driver.I got the formulas from the spreadsheet in this post:http://www.mycncuk.com/threads/1524-What-size-stepper-motor-do-I-needCorner speed = 191 * Supply voltage / (Rated current * Winding inductance)Torque below corner speed = (Holding toque * Set phase current / (sqrt(2) * Winding inductance) ) - Detent torqueTorque above corner speed = ( (Torque below corner speed * Corner speed) / Speed ) - Detent torqueAre these formulas correct / reasonable approximations?I'm particuarly uncertain about the corner speed formula, because I don't know where 191 comes from and the calculated corner speed is higher than what I get from speed-torque curves from stepper manufacturers.Coil resistance is also ignored, this seems reasonable as long as the driver is limiting the current, which I think will only be the case below corner speed?Emil
Calculating trace length matching requirements? - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: February 26, 2018, 10:22:33 pm
content: I've been making an effort to make sure that all my designs are as detailed as possible. One thing I would like to do would be to include a "layout note" for all communication buses specifying required trace length matching.I'm working with a Microchip USB3300. This enables USB-HS off of a microcontroller to DMA data faster. The communication between the microcontroller and the PHY is ULPI with a 60MHz clock.http://ww1.microchip.com/downloads/en/DeviceDoc/00001783C.pdfNow, when working this slow it should be difficult to make it fail but I want to calculate it and put it on the print. On page 19 of the datasheet it mentions a 5ns setup time. To my understanding I should be able to assume a propagation delay of 150ps/in. Would this really put me at a required length match of +/- 15 inches? I thought this would be +/- 1in at most at this speed.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 27, 2018, 02:07:47 am
content: Why should that be so unbelievable?Tim

author: Teledog
author_rank: Regular Contributor
timestamp: February 27, 2018, 05:02:44 am
content: I'm a dough-head here (and admit it).I asked our board designer about all the "squiggly" traces on the PCB.He showed me that the parallel timing between the memory & CPU had to be exact, hence the "squiggly" traces - to ensure all trace lengths were identical.He kept the memory as close as possible to the CPU (using Altium, IIRC)You probably know that..but interesting reading for others anyway..

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 27, 2018, 07:42:26 am
content: Well-- if you're a certified dough-head,it might just seem like fancy things. If you're a halbfertigerkopf (I think?), you might ask -- correctly -- whether the squiggles are appropriate or not. If you're completely clear, you might simply ask: what is the setup and hold time, and how much distance does it really matter? The latter, is what the OP has asked.I'm guilty of it too, sometimes I add squiggles even though the bus doesn't need length matching, at least not nearly to the magnitude implemented. It's more just for swag on the artwork, than for real electrical purpose.And this thread is a perfect illustration of this -- sub-nanosecond interfaces need fairly tight matching, but multi-nanosecond interfaces would have to be extremely gross (say, running the signals overmultiple separate ribbon cables of disparate lengths) to actually violate the timing restrictions.Tim
Calculating transformer winding ratio for 600 ohm > 8 ohm  - Page 1
Forum section: electronics / projects

author: RockyRaccoon
author_rank: Newbie
timestamp: January 25, 2019, 05:34:33 pm
content: I have designed an amplifier with an output impedance is around 600 ohms. I want it to drive an 8 ohm speaker, so I am trying to calculate the proper transformer winding. I’m finding very little information on this so I’ve come here to ask for help — how do I calculate the proper transformer winding ratio to turn a signal with 600 ohms of resistance to a signal with 8 ohms of resistance? If it’s a common enough ratio I’ll order it but if not I have a machine that I use to wind guitar pickups that I’ll use to make it myself. Thanks!

author: Benta
author_rank: Super Contributor
timestamp: January 25, 2019, 06:27:39 pm
content: The rule is that impedance transformation is the square of the winding ratio.In your case sqrt(600/8) = N.

author: RockyRaccoon
author_rank: Newbie
timestamp: January 25, 2019, 06:35:15 pm
content: Quote from: Benta on January 25, 2019, 06:27:39 pmSo I’m understanding you properly, the ratio should be 8.66:1?600/8 = 75 and the square root of 75 is 8.66Thank you.

author: DaJMasta
author_rank: Super Contributor
timestamp: January 25, 2019, 06:43:06 pm
content: Exactly. You can find RF transformer calculators around the net that will confirm this, also can give you an idea of losses for a given core material. Here's one that gives you a bit more than just turn ratio, but there are many options:https://www.changpuak.ch/electronics/broadband_transformer_matching.phpFor good low frequency response, you're going to want a good number of turns.

author: floobydust
author_rank: Super Contributor
timestamp: January 25, 2019, 08:27:00 pm
content: You won't get a lot of power, maybe a few W at most unless your 600 ohm source is capable of a lot of output voltage, like a Pultec EQ.To experiment, a 120V-12.6V power transformer is around 9.5:1 turns ratio. So 600 ohm input and 6.6 ohm output.
Calculating VSWR from complex impedance - Page 1
Forum section: electronics / projects

author: w3amd
author_rank: Regular Contributor
timestamp: December 29, 2015, 11:38:53 pm
content: Hi all,I see a bunch of internet references for performing an SWR calculation but they seem to be based on real impedance. Does anyone know a reference to calculate VSWR based on a complex impedance when Z0 = 50.TIAJohn

author: rfeecs
author_rank: Frequent Contributor
timestamp: December 29, 2015, 11:52:42 pm
content: First result on Google:http://www.rfcafe.com/references/electrical/vswr.htmCalculate the reflection coefficient from the impedance and Z0. Then VSWR from the magnitude of the reflection coefficient.

author: w3amd
author_rank: Regular Contributor
timestamp: December 30, 2015, 12:12:19 am
content: Sorry, I don't see any way yet to go from the complex number.Load Impedance (Ohms) = 9.33E+0-3.92E+01jI'm thinking for radio calculations that the real part is what is called R and the imaginary is called X. So I have 9.33 R and -39.2 X.The end result should be an VSWR of around 8 from a 50 ohm source.I also tried to calculate from the supply power to radiation efficiency but this number is also incorrect resulting with 17.94 -> 100W output = 80W radiatedVSWR ReturnLoss(db) Top17.94427191 0.9691001301 2.1180339887Bottom0.1180339887Watt dbW1.00E+002 208.00E+001 19.03089986990.9691001301John

author: rfeecs
author_rank: Frequent Contributor
timestamp: December 30, 2015, 12:35:45 am
content: Calculate the reflection coefficient (Gamma):Gamma = (ZL-Z0)/(ZL+Z0)ZL = 9.33 - j39.2Z0=50Gamma = (9.33 - j39.2 - 50)/(9.33 -j39.2 + 50) = (-40.67 - j39.2)/(59.33 - j39.2) = -.173 - j.775Mag(Gamma) = .794Calculate VSWR from magnitude of reflection coefficient:VSWR = (1 + Mag(Gamma))/(1 - Mag(Gamma)) = 1.794 / .206 = 8.7 : 1

author: hendorog
author_rank: Super Contributor
timestamp: December 30, 2015, 12:36:20 am
content: I typed the rfcafe calcs into Octave and this is the output:(lines starting with >> are user entered. Lines without >> are the responses)Code:>> zl=9.33-39.2izl = 9.3300 - 39.2000i>> z0=50+0iz0 = 50>> t=(zl-z0)/(zl+z0)t = -0.17330 - 0.77521i>> v=(1+abs(t))/(1-abs(t))v = 8.7250so VSWR = 8.725

author: w3amd
author_rank: Regular Contributor
timestamp: December 30, 2015, 12:44:37 am
content: Thanks guys I got it now!I was thinking the wrong way about what to do with the imaginary part instead of just converting Z0 into imaginary. Big duh.John
calculator for measuring the permeability of ferrite rods? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: September 07, 2018, 12:27:43 am
content: Torroids I found:http://coil32.net/online-calculators/determine-toroid-core-permeability.htmlhttp://zpostbox.ru/how_to_determine_permeability_of_unknown_cores_online_calculator.htmlHow about rods? Have any of you used a formula and compared it to the manufacturers specification so I can get an idea of how accurate a proposed method would be? I am only interested in signal level behavior.Is there anything to watch out for, especially with long ferrite rods (like antennas?).. Like coil length in relation to the length of the rod?This table looks useful for determining effective permeability:http://www.magneticsgroup.com/pdf/erods.pdfBut how about material permeability?This is the best I found:http://www.sklaic.info/forum/index.php?topic=175.0Accuracy is kind of cryptic. Does anyone have more insight? And his graph disappeared.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 07, 2018, 05:12:52 pm
content: It's mostly air gap, so the best you can say is it's "good enough".See:Note that the curves cut off at higher mu, where they go asymptotically vertical (air gap dominates over core reluctance).I would be surprised if you found any ferrite rods that were low enough permeability for this to matter. Powder rods maybe, but those must be pretty rare, I've not seen any that I know of (I'm sure they're out there, though!).Tim
Calculator SMPS ,,all in one" (english) - Page 1
Forum section: electronics / projects

author: Pixel
author_rank: Newbie
timestamp: March 26, 2021, 05:27:18 am
content: I found separate software in English for designing SMPS power supplies, but I haven't seen one called "all in one". Is there a version in English?I found a similar topic here on the forum as wellhttps://www.eevblog.com/forum/projects/do-we-have-an-english-version-of-this-very-cool-calculator-(excellentit)/
CalcWatch, part number for switches - Page 1
Forum section: electronics / projects

author: frank26080115
author_rank: Regular Contributor
timestamp: December 03, 2010, 01:06:43 am
content: Hi I'm interested in the tactile button switches used on the CalcWatch, who makes them and how can I find them?

author: EEVblog
author_rank: Unknown
timestamp: December 03, 2010, 05:00:48 am
content: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P12237SCT-NDDave.

author: frank26080115
author_rank: Regular Contributor
timestamp: December 03, 2010, 05:37:17 am
content: Ah thank you, I was filtering out the through-hole options, I'm disappointed that these are not surface mount but I'll see what this manufacture has to offer
Calibrating Instrumentation Amps - Page 1
Forum section: electronics / projects

author: alihashemi
author_rank: Newbie
timestamp: July 26, 2015, 03:10:07 am
content: Hi All:I'm doing one of my first designs and it includes the INA129. I have a differential signal that is 50uV pk-pk. I have a gain of 10,000 configured on the 129. What is the best way to ensure that I have 0V at zero input and 500mV at full scale? I was thinking a DAC for the zero and a resistor divider using a pot at the output. Thoughts? Would it better to go with a chopper amp? I would need the pot resistor divider to give me all the way down to 1mV or even .1mV steps. Is this even a good idea? Sorry if this is a stupid question!Thanks in advanced!Ali

author: Vgkid
author_rank: Super Contributor
timestamp: July 26, 2015, 03:53:52 am
content: I assume that you have your shielding all sorted out, you will need itFor zero, short the inputs. This will show why shielding is inportant.For the 50 uv use a voltage divider to divide a stable known voltage to the desired amount. For this it would be good to have the output the largest voltage it can(using a voltage much higher than 50uv).

author: MagicSmoker
author_rank: Super Contributor
timestamp: July 26, 2015, 12:16:10 pm
content: The higher grade version of the INA128/129 has a worst case Vos of 50uV which is the same magnitude as your max signal, so that ain't gonna work. I would pick an instrumentation amp with a Vos of around 0.5uV to do the differential amplification and only have it amplify by 100x, then follow that with a good quality standard op-amp to get the final 100x amplification (this approach especially recommended if you need also need the frequency response to go beyond ~10kHz).

author: alihashemi
author_rank: Newbie
timestamp: July 26, 2015, 04:55:42 pm
content: My thought process was to have a 5V source connected to terminal A of a pot, then the wiper connected to my -S input signal and the terminal B connected to ground. +S and -S will be in reference to ground of my circuit as well. But, I see that you're right. For some reason I was thinking the offset voltage for the 129u was 10uV, not 50uV. If its 50uV it'll be impossible to calibrate! Hm, what're your guys thoughts on two choppers configured as an instrumentation amp? I wouldn't really need to calibrate the zero anymore, just the output, yes?

author: MagicSmoker
author_rank: Super Contributor
timestamp: July 26, 2015, 06:01:38 pm
content: The "two op-amp instrumentation amplifier" circuit suffers from poor CMRR due to imprecision in the matching of the resistors, but rolling your own InAmp using chopper amplifiers is a good idea otherwise; just use the standard 3 op-amp circuit (NB - buy a quad chopper op-amp IC like the LTC2052 or LC1053 and then use the extra op-amp as a second gain stage).

author: alihashemi
author_rank: Newbie
timestamp: July 27, 2015, 01:52:44 pm
content: Thank you very much for the advice. I'm going to order a quad 2052 and 1053 and test both of them out.Thanks again.
Calling all developers and electronics enthusiast from BRAZIL BRASIL - Page 1
Forum section: electronics / projects

author: rvalente
author_rank: Frequent Contributor
timestamp: October 16, 2020, 05:41:43 pm
content: Hello Brazilian mates,beeing the eevblog a serious electronics forum I'm sure there is no better place to that.We all know the difficulties to get electronic components and eventually test and measurement gear here, so this holds off our research and technology development. There was never digikey/mouser/RS here and Farnell gave up on Brazil around 2015$10 in parts + $40 (shipping) in digikey turns outs to be $95 after import taxes, this is nonsense.So I was wondering how many of you would help me to gather some signatures online to pressure government and make our hobby/profession easier? (sure, we would need a congress person, but that's not that hard).If you agree please PM with your e-mail or post it bellow.GreetingsPORTUGUES:Olá amigos, tudo bem?O EEVLGO é um dos mais sérios foruns de eletrônica, penso que é um bom lugar para isso.Todos nós sabemos das dificuldades em obtermos componentes e equipamentos de teste e medição por aqui, isso causa um enorme atraso na nossa ciência, pesquisa e desenvolvimento tecnológicoPor aqui nunca tivemos Digikey/Mouse/RS e a Farnell foi embora em 2015Comprar 10 dólares de peças + 40 dólares de frete acabam virando 95 dólar com taxas e impostos, sem noção.Então eu me pergunto, quantos de vocês apoiariam juntarmos algumas assinaturas online para pedirmos ao governo e tornarmos nosso trabalho e hobby mais fácil (com ajuda de algum deputado)Se concordarem, me enviem uma mensagem com seu email ou deixem-o aqui.Abraços
Calling all Filipino speakers  - Page 1
Forum section: electronics / projects

author: iXod
author_rank: Frequent Contributor
timestamp: March 23, 2023, 12:28:20 pm
content: To the best of my abilities to listen to a foreign language and pick out the few English words and visual clues, this YT video describes disabling backlight voltage protection on an LG LED TV.By pinning pin-13 to ground, a misbehaving backlight circuit can be diagnosed.I would be grateful for any further details that a native speaker could glean from the video.Thanks.
Calling for Help - Identify this 12-pin HP connector please? - Page 1
Forum section: electronics / projects

author: guarneri0
author_rank: Contributor
timestamp: July 20, 2019, 04:50:57 am
content: I just bought an HP 8672a on ebay, along with the frequency extension unit (HP 86720a.) They both need to be connected via a cable, but the cable is missing. I can't seem to be able to find a cable online, so might have to make one.Attached is an image of how the connector looks like on the Frequency Extension Unit. The same connector is on the main HP 8672a unit, so need a female to female cable to connect the units.I have tried searching for all 12-pin round connectors on Mouser and other places and can't seem to find the one that looks exactly like this. Any help to identify this connector (and/or cables made for them) would be highly appreciated!Thanks a lot!--guarneri0

author: bob91343
author_rank: Super Contributor
timestamp: July 20, 2019, 05:05:29 am
content: Well it appears that the connector is mounted with a snap ring so if it were mine I would find a different connector. But I would do it in such a way that I could restore the original configuration in case I found a cable.For a while, Google had an application where you could submit a photo and they would match it. But I haven't seen that in years.An HP parts list would likely list the cable as well as the connectors, and I suppose you could order one from them.There are some DIN connectors that might be pressed into service to work here. You might also need to know if there are any shielded wires or any jumpers.

author: guarneri0
author_rank: Contributor
timestamp: July 20, 2019, 05:57:47 am
content: Thanks a lot Bob for your response.When you say "if it were mine I would find a different connector" - do you mean that I can just take this connector off, desolder the wires connected to this one, and solder another connector to the wires etc? I can look into doing this.So far, I have only found this link that shows the cable I need, but seems like it is going be a custom order, if they are still willing to make it etc:https://4gte.com/products/hp-agilent-8120-3720-interconnect-cable-86720a-to-8672a/So the HP part number is "8120-3720" but I can't seem to find it anywhere else online to purchase (even tried *bay..)Any other concrete suggestions would be really welcome - just want to be able to connect the two units together and try them out!Regards,--guarneri0

author: guarneri0
author_rank: Contributor
timestamp: July 20, 2019, 06:23:31 am
content: (Posting in case anyone else might run into this.)After some more searching, found this very useful info on keysight forum:https://community.keysight.com/thread/17367Based on this, looks like "8120-2703 attenuator cable" will work, and these I can find on *bay.Cheers,--guarneri0