hybridfree/eevblog-posts huggingface dataset:
Measurement with a Curve Tracer - Page 1
Forum section: electronics / beginners

author: watchmaker
author_rank: Unknown
timestamp: January 23, 2025, 11:52:49 am
content: While this may be better posted in the "Show your curve tracer" thread, I figure most of those readers are well acquainted with how to use the instrument.I have been learning about transistors recently and pulled out my Heathkit Curve tracer. I was surprised just how useful it is.But the presentation on measurements is very clear.The section describing measurement is attached. And for the curious, the cost difference of "real" curve tracer as opposed to a "toy" like the Thaikit is maybe $100 by the time you add in the required parts for the kits.While discrete transistors are essentially obsolete, their study is useful if you want first principles.
Measuring 3-phase power with Rigol DS1054z - Page 1
Forum section: electronics / beginners

author: omglol
author_rank: Regular Contributor
timestamp: June 19, 2017, 10:06:49 pm
content: Hi!I would like to measure power of the 3-phase machine using my 4-channel scope Rigol DS1054z. I would like to do this using this method here:http://teledynelecroy.com/doc/threephase-power-measurements-using-a-fourchannel-scope-to-measure-threephase-powerI can borrow differential and current probes, however, I doubt that my Rigol can do these calculations itself. What would be the easiest solution to calculate power? Record waveforms and then somehow export data to Matlab or something similar? Can anyone shed some light here? Thanks.

author: omglol
author_rank: Regular Contributor
timestamp: June 20, 2017, 10:00:15 pm
content: Any hint here, please?

author: Vtile
author_rank: Super Contributor
timestamp: June 20, 2017, 10:18:55 pm
content: You can also use excel for the analysis. I'm not going to math part typing with this phone. PS. I'm not familiar on Rigol scopes, but I would be suprised if there would not be math and analytics functions inbuild.. RMS(mean/integral), phase angle (in cursor menu) and peak value.. etc. Rest of the article looks like using straight forward "frozen phasors" method (right term escaped from my head) in calculationss. The differential and current probes are essential for your safety.
Measuring "current direction" in a resistor? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: June 10, 2013, 09:35:51 pm
content: A fault test asks I measure the "current direction" in a resistor, with an expected very low value. I quote:"Ideally this should be feeding in a tiny bias current to the transistor. Possibly less than 0.5uA so there will be just a few mV drop in R116 (22K) at the base of Q49 on a healthy unit"How would I do this test please?Thanks.

author: c4757p
author_rank: Super Contributor
timestamp: June 10, 2013, 09:38:50 pm
content: Measure the voltage across it...

author: DavidDLC
author_rank: Frequent Contributor
timestamp: June 10, 2013, 09:53:57 pm
content: Quote from: c4757p on June 10, 2013, 09:38:50 pmAnd check it's polarity

author: mikes
author_rank: Regular Contributor
timestamp: June 10, 2013, 10:04:01 pm
content: ...and understand that the convention is that current flows from + to -.
Measuring AC line quality with a digital oscillocope (Rigole 1054Z) - Page 1
Forum section: electronics / beginners

author: lturcotte
author_rank: Newbie
timestamp: September 04, 2015, 10:16:13 pm
content: I recently bought my Rigol 1054Z DSO (digital oscilloscope) and I wanted to measure the amount of spikes and AC line noise especially during a thunder storm. Wondering if I need to add isolation in front of the scope other then standard 10X probes and wondering if the oscilloscope has a mode to capture multiple waveforms in memory or can it only capture a single waveform based on a trigger level, for example anything that exceeds 200V (ac lines here in the us are 120V)Thanks

author: lturcotte
author_rank: Newbie
timestamp: September 05, 2015, 12:47:57 am
content: I found most of my answers here about isolation and ground considerations for AC main lineshttps://www.eevblog.com/forum/beginners/how-to-mesure-240v-ac-with-an-oscilloscope/

author: lturcotte
author_rank: Newbie
timestamp: September 05, 2015, 12:49:01 pm
content: Question is if you use an AC isolation transformer as it is recommended in the other thread (https://www.eevblog.com/forum/beginners/how-to-mesure-240v-ac-with-an-oscilloscope), do you still pick up transients and voltage spikes from the AC mains

author: mij59
author_rank: Frequent Contributor
timestamp: September 05, 2015, 01:22:33 pm
content: Quote from: lturcotte on September 05, 2015, 12:49:01 pmA isolation transformer is used to power the device under test, for measuring a low voltage transformer e.g. 110V /6V will do.Transformers design for 60 Hz will not be very efficient for detecting high frequency signals, with are present in voltage transients.Best way would be to use a differential probe, or even better do not probe the line voltage during a thunder storm, disconnect sensitive equipment from mains !

author: Circlotron
author_rank: Super Contributor
timestamp: September 05, 2015, 01:32:05 pm
content: Some toroidal mains transformers have a frequency response that might be good enough.

author: lturcotte
author_rank: Newbie
timestamp: September 05, 2015, 09:01:04 pm
content: I am thinking of hooking up my isolation transformer to a function generator on the primary to see the frequency response.
Measuring AC voltage with multimeter - Page 1
Forum section: electronics / beginners

author: Google+SucksBalls
author_rank: Newbie
timestamp: August 23, 2015, 06:55:32 pm
content: My electronics knowledge is a bit rusty, so I'm double checking here.. I'm having some trouble measuring voltage with arduino: the readouts kept fluctuating. So I figured out something is wrong with my aref/power supply. So I measured the voltage of the usb, which I'm using to supply the arduino and it is 4.6v steady. But when I switch to AC voltage measure, I should expect near 0V, right? It's reading 0.3V - does that mean the usb power is going up and down for 0.3V? I don't have oscilloscope to double check it..thanks,Žiga

author: PSR B1257
author_rank: Frequent Contributor
timestamp: August 23, 2015, 07:09:12 pm
content: QuoteNot necessarily. It could be even worse. The multimeter is calibrated for a sinusoidal wave and can only measure those correctly. With any other wave form (unless you know the type) it can pretty much display everything.Nevertheless, if it reads 300 or whatever mV, there is something seriously wrong the supply rail.

author: Rolo
author_rank: Regular Contributor
timestamp: August 23, 2015, 07:24:15 pm
content: My experiance with arduino and ADC is not to use your computer`s USB as powersupply. It fine for the digital I/O but the ADC needs a better power source. Try powering it external with a simple linear power supply and will improve a lot.

author: Google+SucksBalls
author_rank: Newbie
timestamp: August 24, 2015, 05:44:42 pm
content: Thanks for answers!It was a blown capacitor on psu of usb hub.
Measuring Ambient Temperature - Page 1
Forum section: electronics / beginners

author: MostlyCarbon
author_rank: Newbie
timestamp: July 05, 2011, 01:25:00 am
content: Hi there,I'm working on a project, essentially a humidity and ambient temperature sensor. I'd like it to run on batteries and the standard LM35 needs 4V. I'd like something that can run on 3V and will work all the way down to (preferably) 2V.I'm wondering about the suitability of an IC like this:http://datasheets.maxim-ic.com/en/ds/MAX6607-MAX6608.pdfHow does an IC in the SOT23 vs. TO packages ability to measure the ambient temperature vary? The SOT will get more of the heat from the board... which should be negligible?Any other tips to getting a good ambient temperature reading?Thanks,MostlyCarbon

author: ivan747
author_rank: Super Contributor
timestamp: July 05, 2011, 02:54:59 am
content: For me the LM35 is a PITA for digital electronics. It is analog so if you are using a DC-DC converter you should use some heavy filtering. Depending on the board layout, the DC-DC converter might introduce some heat to the system. I like the TO-220 version, it can be mounted on a big surface like a metal chassis. If you are using this with a digital circuit please do yourself a favor and get a humidity sensor IC with integrated temperatur sensor. Go for something that supports I2C, SPI or at least RS-232.

author: MostlyCarbon
author_rank: Newbie
timestamp: July 05, 2011, 03:15:13 am
content: Fortunately the Humidity sensor section at DigiKey is small (53 options).There is also this thingy from Parallax:http://www.parallax.com/Store/Sensors/TemperatureHumidity/tabid/174/CategoryID/49/List/0/SortField/0/Level/a/ProductID/94/Default.aspxIt does a nice digital output of both temperature and RH (relative humidity) but it's also $35 a pop. Almost double the cost of implementing them separately.I plan on using a PIC18 to do the A/D and then ZigBee the info to the master. I'll have multiple units.Mainly I'm just interested in ensuring that the temperature info accurately reflect the ambient rather than the internal/pcb temperature. And the layout/design issues that I should consider to help me get the best accuracy I can (or at least avoid overly in-accurate results).As it turns out the lowest Vs I could find in a RH sensor is 2.7v. So I'd like to use a Temperature sensor with Vs minimum ~ 2.7v.MostlyCarbon

author: ivan747
author_rank: Super Contributor
timestamp: July 05, 2011, 01:29:12 pm
content: Go for the TO-220 or something that sticks out of the board. You may want to have the hot parts away and do some sort of thermally resistive path for the ground plane. I can't recommend any thecniques because I am not into real EMI stuff yet. (If you have a high speed circuit with RF components, then you have to be careful about the layout).
Measuring and displaying frequency and amplitude - Page 1
Forum section: electronics / beginners

author: CodyW
author_rank: Contributor
timestamp: August 06, 2013, 02:51:37 pm
content: G'day Everyone,I was just wondering if anyone knew how could I go about measuring and displaying the frequency and amplitude of a wave onto a 8x2 LCD screen? How hard would this be?Thanks,Cody

author: KJDS
author_rank: Super Contributor
timestamp: August 06, 2013, 03:18:17 pm
content: Audio? RF? dynamic range required?

author: CodyW
author_rank: Contributor
timestamp: August 06, 2013, 03:25:10 pm
content: Quote from: KJDS on August 06, 2013, 03:18:17 pmJust audio.

author: Dave
author_rank: Super Contributor
timestamp: August 06, 2013, 03:30:17 pm
content: Like a graphic equalizer?Look up FFT (Fast Fourier Transform).

author: Marco
author_rank: Super Contributor
timestamp: August 06, 2013, 04:54:21 pm
content: There are a couple microcontroller spectrum analyser projects using FFT... you could just adapt one of those and just look for the largest component, this will give you a frequency and amplitude.Not necessarily precise enough, but then you haven't said what kind of precision you want.

author: Zad
author_rank: Super Contributor
timestamp: August 06, 2013, 05:11:34 pm
content: If you know that you are measuring a single frequency (pure sinusoid) signal, you can just measure the time between zero-crossing points.
Measuring bandwidth - Video transmitter Saw filter upgrade - Page 1
Forum section: electronics / beginners

author: Teklock
author_rank: Newbie
timestamp: July 22, 2014, 07:52:15 pm
content: Guys, I'm completely new to this so take it easy...I'm about to upgrade the saw filter in a 900MHz-1.3GHz wireless video receiver, but I want to take measurements to see if it actually improves anything. The saw filter mod is a popular one with the FPV folks. Unlike the 2.4GHz and 5.8GHz A/V systems that were purposely designed for A/V applications, the 900MHz - 1.3GHz models are older designs that use a baseband RF tuner developed for the satellite receiver industry. So swapping the 27MHz filter for the 17MHz gains some performance.I can get the RSSI voltage np, but I would like to get the bandwidth and sensitivity before and after. I Have a 75 ohm resistor across an RCA jack as a terminator to fine tune with my SDS7102. I'm just shining a flashlight at the camera to try to get a fully saturated white level. I have access to a AG2052F waveform generator. Is there a way to use that instead to get a "reference" instead of using my transmitter? I also have access to a USRP B210 SDR, so I can get some gain info, but I still don't feel like i''m getting the correct sensitivity.
Measuring clocks - Page 1
Forum section: electronics / beginners

author: johndon2000
author_rank: Contributor
timestamp: June 14, 2013, 07:52:22 am
content: Is there a way of reliably checking clocks as I've had a few issues.I've had intances where a XTAL seems to be faulty but the cct is working fine (eg a 33MHZ clock is actually only 31MHZ but the cct still works ok)... but then I've had instances where the clock seems ok (it is 33MHz and amplitude etc seems oK) but the circuit isn't working, so I've replaced the clock and the fault clears!Is it just me that has this issue of not being able to reliably see if a XTAL is working?!

author: AndyC_772
author_rank: Super Contributor
timestamp: June 14, 2013, 10:36:39 am
content: Bear in mind that what you're seeing is the behaviour of an oscillator when the extra capacitance of a scope probe is added. I tend to avoid designing with simple crystals wherever possible, because they can be rather sensitive and unpredictable; an integrated crystal oscillator module is more expensive but virtually guaranteed to be reliable - and because the output is buffered, you can probe it with a scope without affecting its frequency.Borderline cases like these where some crystals don't oscillate at all, or at the correct frequency, probably indicate that the crystal, the capacitors and the drive level from the logic inverter aren't properly matched. It's a design issue that should be checked by the engineer who specified the particular components, and in particular, someone needs to check that the specific parts called up by the engineer haven't been substituted for apparently equivalent ones by someone unqualified to make that decision.Sometimes it can help to probe other signals that should be derived from the master clock, rather than trying to probe the crystal itself. If, for example, a microprocessor has a PLL in it which uses the crystal as its reference, the outputs of the PLL will give a strong clue as to whether or not the master clock is OK. If, say, there's a 33MHz input from a crystal and a 100 MHz output from the CPU going to the DRAM, then if that 100 MHz clock is OK then the reference crystal probably is too.
Measuring COB LED temperature - Page 1
Forum section: electronics / beginners

author: made2hack
author_rank: Frequent Contributor
timestamp: November 26, 2017, 09:38:51 am
content: Hi all,So I've been playing with a LED COB for a project and wanted to gauge the temperature it reaches when run at various currents. The COB LED in question has an exposed test point on the surface which gives you the case temperature.The way I've been measuring it is to simply kapton the tip of my thermocouple to the point and hope to get a reasonably measured temperature. Has anyone had experience with measuring temperatures this way? What is the proper way of doing it? Is it a fixed jig using pogo pins? Could I perhaps solder the tip of the thermocouple to the pad? Will this kill the thermocouple?Thanks,

author: Ian.M
author_rank: Super Contributor
timestamp: November 26, 2017, 11:56:07 am
content: You've got poor thermal contact, and far too much heat loss up the thermistor wires. The best option would probably be a SOT23 temperature sensor IC, with hair-thin magnet wire (40AWG ?) for the connections, pressed into a small block of expanded polystyrene, with a tiny dab of heatsink compound on it, flipped over onto the test spot and held in place by a spring finger.

author: Gregg
author_rank: Super Contributor
timestamp: November 26, 2017, 05:45:53 pm
content: If you are interested only in relative temperature changes with different LED controls what you are doing is on the right track. As Ian stated, there will be heat conduction into the thermocouple wires which can be reduced by using the smallest available thermocouple wires and making sure there is the best possible thermal connection with the relatively tiny measurement location.Some good thermal compound that is not electrically conductive at the measuring point will help; but if it is electrically conductive, it will throw off the thermocouple readings. I can’t tell from your picture, but you may already have thought of this.Do not solder the thermocouple. Thermocouples generate a tiny voltage at the junction of two dissimilar metals and solder would in effect short out the output at the source.I see kapton tape covering a lot of the heatsink; if you are attempting to test the LED and heatsink combination, it would be better to make a little dog clamp out of non-conductive material (plastic, fiberglass, etc.) that would hold the tip of the thermocouple in place and hold the LED module against the heatsink at the same time.
Measuring average current to estimate battery capacity - Page 1
Forum section: electronics / beginners

author: msr
author_rank: Regular Contributor
timestamp: June 17, 2012, 04:43:42 pm
content: Hi everyone,I designed a circuit with a PIC24F and a couple more components and now I want to measure it's average current in different modes (run, idle, sleep) to later estimate the battery capacity I'll need. What sould be the best procedure to accomplish that? Im expecting to get very small currents, in the range of ~100mA (run/idle mode) and ~10's uA (sleep) or even ~100's nA (deep sleep).I have a Rigol DS1052E Osciloscope and a Batronix BXM98P multimeter (true rms, 4 1/2 digit). I can also borrow an current probe if needed.I considered to use a 1ohm resistor in series with circuit's VDD, two osciloscope probes and use ADD function of the osciloscope to get a differential voltage across the sensing resistor. I don't know if this method is reliable to measure such small currents due to osciloscope's vertical noise and CMRR between the two probes.What are your suggestions?Thanks

author: SeanB
author_rank: Super Contributor
timestamp: June 17, 2012, 05:05:25 pm
content: Buy one of Dave's microcurrents...........

author: T4P
author_rank: Super Contributor
timestamp: June 17, 2012, 05:47:22 pm
content: 100mA ... Didn't know the 24E was so power hungry, that puts in on par with the STM32F407VGT6 ( Not that it matters ... )

author: msr
author_rank: Regular Contributor
timestamp: June 17, 2012, 05:55:37 pm
content: Quote from: DaveXRQ on June 17, 2012, 05:47:22 pmPIC24Fare not that power hungry. If you see the datasheet you'll notice it consumes (typical values) ~15mA at 16MIPS ("normal" mode), ~3.5mA in Idle mode. But in the board I designed I can have additional modules like WiFi or SD card which will certainly consume more current (~10-100's of mA).As far as I can understand Dave's uCurrent is good to use with multimeters due to Burden Voltage. However I don't know if that voltage also affects osciloscopes. If don't, it seems it doesn't make sense to buy uCurrent to use with an o'scope. Please let me know if Im wrong.

author: MikeK
author_rank: Super Contributor
timestamp: June 17, 2012, 05:58:31 pm
content: If the max current is going to be 100mA through a 1 ohm resistor, why not feed that voltage to an op-amp with a gain of at least 50?

author: SeanB
author_rank: Super Contributor
timestamp: June 17, 2012, 06:02:33 pm
content: Microcurrent is a low drop current to voltage converter, and has a pretty good bandwidth, so will work wel as a scope probe add on. Just make sure to consider the grounded lead of the scope does not cause any problems, either by using a differential probe or an isolated scope.

author: T4P
author_rank: Super Contributor
timestamp: June 17, 2012, 06:22:36 pm
content: Quote from: msr on June 17, 2012, 05:55:37 pmOops. F it is then, but if the F (which is a slower part) is that much power already, the E will definitely chew quite a lot, i just check'd the schem and it is indeed 100mA ... for the E
Measuring Current in Inductor Circuit - Page 1
Forum section: electronics / beginners

author: eev_carl
author_rank: Regular Contributor
timestamp: August 21, 2017, 02:16:06 pm
content: Hi,I'm measuring the current in an inductor circuit, but it doesn't match my calculated values. I was wondering if someone could explain the discrepancy to me. The circuit is 10 x 1uH inductors in series with an AC voltage source of 1.77V at 25KHz. I calculated the reactance to be 1.57 ohms and the current to be 1.13 A (1.77 / 1.57). However, when I measure the current with a DMM, I get 14.2uA.This is a link to the inductors that I'm using:http://www.mouser.com/ds/2/390/RCH-654-523455.pdf.Thanks,Carl

author: Benta
author_rank: Super Contributor
timestamp: August 21, 2017, 02:48:57 pm
content: Is your DMM able to measure anything at 25 kHz? BTW, I get 1.57 as well.

author: eev_carl
author_rank: Regular Contributor
timestamp: August 21, 2017, 03:09:28 pm
content: Hi,Thanks for replying. In the DMM manual, it lists a frequency range of 50 to 400Hz. My DMM is a Klein Tools MM700.-Carl

author: Benta
author_rank: Super Contributor
timestamp: August 21, 2017, 04:40:16 pm
content: A long way up to 25 kHz, then.

author: Zero999
author_rank: Super Contributor
timestamp: August 21, 2017, 09:50:52 pm
content: Use an oscilloscope and sense resistor or current transformer. Note that the oscilloscope's chassis will be connected to mains earth and if your 25kHz signal source is to, the sense resistor idea may be a no goer: use a current transformer instead.
Measuring Current into a Boost Regulator - Page 1
Forum section: electronics / beginners

author: wholder
author_rank: Regular Contributor
timestamp: June 24, 2018, 01:36:02 am
content: I'm designing a battery powered device that runs on 2 AAA cells boosted to 5 volts using a SEMTECH SC120, Low Voltage Synchronous Boost Regulatorhttps://www.semtech.com/uploads/documents/sc120.pdfthat, in turn, powers an ATTiny84A and some other circuitry. I want to measure the current draw from the batteries under different load conditions, so I connected my multimeter in series with the battery input, as that seemed like it should work. Wrong... Instead, I get all kinds of weird symptoms ranging from the multimeter sometimes showing a large current draw of 300 mA, vs my expectations of a draw under 30 mA. The ATTiny84A seems to start up, as I see an LED set in the init() code blink once, but then it seems to crash (I have a heartbeat LED that should be flashing if it's running.)I tried adding various additional caps (.1 + 1uF + 100uF + 220uF, etc. in parallel) to the input terminals just before the boost reg input, but I still can't get to the point where the heartbeat LED will flash. I also tried the different current ranges on the meter, but the ATTiny84 flashes the heartbeat LED when I remove the meter from the circuit. BTW, the multimeter is an EXTECH EX330 that I've had for many years. So, what am I doing wrong? Do I need a fancy, desktop multimeter, or is my approach flawed? Any suggestions welcome.Wayne
Measuring Current with Confidence - Page 1
Forum section: electronics / beginners

author: wa2pux
author_rank: Contributor
timestamp: December 23, 2021, 06:13:32 pm
content: Measuring current isn't as simple as you might think. Simply inserting your DVM in series with your circuit may even make your circuit stop working right.So, what is going on inside that DVM?Why does my circuit act funny when I use my DVM to measure current?How can I overcome this problem?Then there are those OLD analog meters with the moving needle ... how do they work?I have answered all of these questions in the video I just uploaded. Here is the link:https://youtu.be/e1q5sOe7mCw

author: wa2pux
author_rank: Contributor
timestamp: December 23, 2021, 08:49:42 pm
content: Not trying to pitch anything. I am trying to help folks with what I post.Rather than restating everything that I say in the video, I simply point them at the video.

author: Benta
author_rank: Super Contributor
timestamp: December 23, 2021, 09:05:24 pm
content: Your video is OK and worth watching for total beginners, but somewhat long-winded (20 min.)I've deleted my previous post, which was triggered by your "sales pitch" approach.

author: jonpaul
author_rank: Super Contributor
timestamp: December 24, 2021, 10:15:30 am
content: WA2PUX:Very fine, we have encountered this issue over the decades as a power electronics engineer, working at up to 300 A.The burden voltage of an ammeter is well defined and most modern DVMs have very reasonable burden and shunt R.I have used 5$ DVMs from Harbor Freight and $1600 Keysight 34465A 6 1/2 digit and never encountered any circuit disturbance IF the range is set and current is with specified range.The best solution for power measurements is a calibrated shunt and voltmeter for DC and a Pearson or equivalent Current transformer for wideband.Just my experience,Kind Regards,JonPS: Another forum group to address is Metrology.
Measuring Electrolytic Caps  - Page 1
Forum section: electronics / beginners

author: carboncomp
author_rank: Newbie
timestamp: January 30, 2014, 06:07:25 am
content: Iv got a relatively new Extech 330 multimeter (got it 3 months ago) but It just wont measure electrolytic above 47uFThe datasheet says the range is 0.001nF to 200?F so guess its faulty or I'm doing something very stupid!Any troubleshooting suggestions?

author: Rerouter
author_rank: Super Contributor
timestamp: January 30, 2014, 06:25:21 am
content: that ? is because there blog software doesn't recognize the micro symbol, so its upper range is 200uF,as for why it cannot handle above 47uF, it could be esr or a leakage current making it think its higher,

author: sleemanj
author_rank: Super Contributor
timestamp: January 30, 2014, 06:49:06 am
content: Quote from: carboncomp on January 30, 2014, 06:07:25 amHow long are you giving it to perform the measurement. Measurement can take quite a while as caps get bigger.

author: carboncomp
author_rank: Newbie
timestamp: January 30, 2014, 12:44:21 pm
content: I'm leaving it a good whiles 20+ seconds (using both clips and probes) but it will just show 0.000uF or sometimes around 20nF on brand new 47+uf caps, and have even tried shorting out the caps beforehand.....think its time to return the bloody thing!
Measuring galvanic voltage - Page 1
Forum section: electronics / beginners

author: jegjessing
author_rank: Newbie
timestamp: October 28, 2020, 08:08:35 pm
content: HiI'm trying to figure out how I can measure the galvanic corrosion on steel pipes.What I have to go with is:A steel pipe within an isolation that in theory should keep water out but, of course there are always some leakage.Between the steel pipe and the isolation there is isolating foam and in this foam there are two copper wires.How can I measure the corrosion that potential leakage results in? I've googled for weeks but are coming to a point were I simply think I cannot find an answer.I find a lot about ZRA, and some other fancy words, but no real schematic/calculations in order to design one myself.I really hope someone here can come with an answer :-)I could in principle just measure the voltage with a milli voltmeter, but since these pipes can be kilometres long the voltage I then measure could be any kind of noise, and not the actual voltage. I could lower this problem by applying a resistance and a capacitor I guess, but since I have no idea of what current it can "drive" I cannot apply any kind of resistance since this would then make the voltage drop :-(You can see an image of the pipe construction here:In advance, thank you SO much!
Measuring Inductance  - Page 1
Forum section: electronics / beginners

author: aniket
author_rank: Contributor
timestamp: December 28, 2016, 05:11:30 am
content: Hi all,I was measuring a inductor at 1Khz/1V and it showed me a inductance of 5mh , but when i changed the test parameter to 1kz/0.250V the inductance changed to 12mh .. DCR of the inductor is 0.4E . I repeated the same test with a smaller inductor of 10uh and its measured inductance stays same irrespective of the test parameter ...why is this happening with the bigger inductor is my test equipment faulty ?? or am I measuring incorrectly ?Regards

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 28, 2016, 05:22:13 am
content: Core permeability varies as a function of flux density (Bmax). Sounds like it's near saturation.Bmax is a rather useless parameter, because you have to know core dimensions and number of turns; it's not something where you can simply apply a known waveform and say it's now running at so-and-so flux density. But anyway, those are the missing parameters, and the rest is just ratios, so it's not like it's some mysterious property.1kHz may also be rather low to be testing at. Though a reactance of ~30 ohms compares favorably to the 0.4 ohm DCR, so it shouldn't be too bad.If reactance were smaller, it would be that much more important that your inductance meter performs a meaningful measurement. (Many testers simply measure the magnitude of the AC voltage or current developed -- capacitor ESR testers very commonly do this -- and so do not take into account the ratio of reactance to resistance.)Tim

author: danadak
author_rank: Super Contributor
timestamp: December 29, 2016, 01:00:12 pm
content: Here is a project using synchronous detection for Z measurement. Cypress PSOC. IDEis "Creator", free, just download it. Note this particular project uses an older versionof Creator, not sure which one, maybe 3.0. So you would need to download that toopen and compile the project. You could then update it at a later time to run with thecurrent version of Creator, 4.0. Or ask the Cypress team to do the update with a postto tech support forum.http://www.cypress.com/products/psoc-creator-integrated-design-environment-idehttps://www.dropbox.com/s/6s7c58fbartcakd/Phoenix%20Impedance%20meter%20project%20and%20info%20HighSpeed%20-%20Copy.zip?dl=0And this might be useful -http://cp.literature.agilent.com/litweb/pdf/5950-3000.pdfAgilent Z Measurement HandbookRegards, Dana.
Measuring Industrial Control Noise with a Spectrum Analyzer - Page 1
Forum section: electronics / beginners

author: connor_v
author_rank: Newbie
timestamp: June 26, 2023, 01:24:41 pm
content: I have a 0-10V signal from a sensor in a industrial environment (~25 meters of shielded cabling) with unacceptable noise (>10mV). I want to see what frequencies the noise is coming from. I have access to a spectrum analyzer, an oscilloscope, and a 6.5V benchtop DMM. I measured the noise with a DMM but it has a built in 200Hz filter so I can't determine frequency. I then measured the noise with an oscilloscope on AC coupling and did a FFT but it can not measure such low of a signal. I am considering getting a LNA10 to amplify the signal and determine it's frequency. Finally I have access to a spectrum analyzer. I was planning to get a DC blocking inline cabling but have a few questions. 1) Am I correct in needing a DC blocking adapter do I need to do any thing else to protect the signal analyzer? 2) Do I need to do a 50 Ohm termination somewhere? 3)What figure in the data sheet of the spectrum analyzer tells me how low of a signal it can measure? 4) any other suggestions for determine where the noise is coming from?Thanks!

author: srb1954
author_rank: Super Contributor
timestamp: June 26, 2023, 09:02:23 pm
content: Quote from: connor_v on June 26, 2023, 01:24:41 pmThe spectrum analyser data sheet should have a figure for the amplitude measurement range. This is usually specified in dBm so you need to convert that into the equivalent mV or uV figure. There are plenty of on-line calculators that will do that calculation for you.If using a spectrum analyser in an industrial environment you should take precautions to protect the spectrum analyser input against transients. Spectrum analysers are very sensitive and the inputs are easily damaged by transients.I would recommend that you at least use a limiter on the input. With the signal levels you are seeing you could also afford to use an attenuator, say 10-20dB, on the input to provide additional protection. Both the limiter and the attenuator should go after the DC block capacitor - this will produce a large spike when initially charging which needs to be clamped by the limiter/attenuator.

author: nick liu
author_rank: Newbie
timestamp: June 27, 2023, 01:34:59 am
content: The spectrum analyser data sheet should have a figure for the amplitude measurement range. This is usually specified in dBm so you need to convert that into the equivalent mV or uV figure. There are plenty of on-line calculators that will do that calculation for you.
Measuring jitter in a sine wave - Page 1
Forum section: electronics / beginners

author: jgalak
author_rank: Regular Contributor
timestamp: February 21, 2018, 09:03:30 pm
content: I have a project that puts out a sinewave under uC control. The algorithm I use to generate it makes me concerned about possible jitter. But I'm not sure how to measure it, or what acceptable/unacceptable amounts of jitter are.The signals are 1200Hz and 2200Hz audio tones (for APRS).The only real tool I have available to me is a Rigol DS1054Z scope, but I don't know how the measurement would be made. A quick Google search found some info on using special scope modes for this, but I can't seem to find any evidence the Rigol has such a mode.

author: ogden
author_rank: Super Contributor
timestamp: February 21, 2018, 09:14:03 pm
content: Quote from: jgalak on February 21, 2018, 09:03:30 pmProper jitter measurements are not that easy. You can see hint of jitter on more or less any scope but measure - only if scope have jitter measurement capability. BTW you can try to measure quality of your audio tones using computer soundcard + audio analysis software.Why you are concerned about jitter? Pick decent MCU with DAC and DMA support or I2S peripheral with DMA + external audio DAC/codec, clock it from external crystal oscillator without using PLL and you will have crystal clear audio tones after filter. How to see jitter using Rigol scopes:

author: danadak
author_rank: Super Contributor
timestamp: February 22, 2018, 01:26:03 am
content: Another technique is to set scope on infinite persistence.Some ref material -http://materias.fi.uba.ar/6644/info/osciloscopios/avanzado/Jitter%20measurement%20with%20scopes/55W-13769-1%20JITTER.pdfhttp://www.electronicdesign.com/energy/get-more-out-your-digital-oscilloscopehttp://anlage.umd.edu/Microwave%20Measurements%20for%20Personal%20Web%20Site/http___www.tek.com_Measurement_scopes_jitter_55W_16146_1.pdf_wt=520&rgn=ww&from=302032X312761&link=_Measurement_scopes_jitter_55W_16146_1.pdfRegards, Dana.
Measuring lag / lead on a scope - Page 1
Forum section: electronics / beginners

author: j.a.mcguire
author_rank: Contributor
timestamp: August 11, 2015, 06:46:58 am
content: Slightly hesitant to ask this for fear of being ostracised as I'm sure the answer is relatively straight forward. I was watching the following youtube video:Where around the 3:30 mark the chap is talking about the effect of inductance to cause current / voltage lag. What I'm interested in is how he was able to connect the scope to simultaneously view the current / voltage for lag and lead?Voltage is easy enough, stick your probe onto the secondary output. But how does one measure current using a scope, since you can't put the scope in line?I suspect a clamp meter / toroid would be the correct method but how is it possible to calibrate the scope to display these readings accurately? Plus the problem as I see it here is the inherent inductance of the clamp meter itself.

author: Simon
author_rank: Unknown
timestamp: August 11, 2015, 07:03:48 am
content: Always remember, no question is too silly to ask. I've not watched the video but a series resistor can be used as a current sense. Although you have to be careful needing a parallel and series connection as you can find your ground shorting. Other devices could work of course.

author: w2aew
author_rank: Super Contributor
timestamp: August 11, 2015, 02:15:39 pm
content: It appears that he is measuring the voltage across the series combination of an inductor, LED and resistor, and then also measuring the voltage just across the resistor. The latter will be proportional to the current.I have a video that describes the voltage and current flow through capacitors and inductors, started with pen & paper, then followed up by some scope measurements:
measuring LC resonance on scope - Page 1
Forum section: electronics / beginners

author: electrolust
author_rank: Unknown
timestamp: May 17, 2017, 01:04:44 am
content: I never know where to post my questions! I feel like all of them are beginner questions.Anyway, I would like to measure the resonant frequency (kHz range) of a parallel LC circuit. I watched Alan's (w2aew) #55 video and the theory and technique seems pretty easy. The total capacitance is in the 100nF range. Therefore, the 11-15pF probe capacitance is neglible and I can just probe across the inductor, yes?It seems so obvious but it's worthwhile to verify my understanding.If OTOH the total capacitance were say in the 50pF or even 100pF range, then the probe capacitance becomes significant and I'd have to put an op amp follower in the circuit to look at its output, yes? Or use a lo-z low-capacitance probe technique, yes?To the best of my understanding, the R of the probe (10M per my expectation) doesn't come into play for resonance but rather just determines the current at the resonant frequency. And so if I did have to use a lo-z probe, I would want to set the signal generator to also be lo-z output.

author: StillTrying
author_rank: Super Contributor
timestamp: May 17, 2017, 01:17:35 am
content: I don't know about down to 50pF on the LC circuit, but you can do it with a SG and 2 resistors of about 5k6. Connect both resistors to the top of the LC, drive one from the SG, and watch for the peak in amplitude with the scope on the other resistor. It works even if the SG is a square wave.

author: w2aew
author_rank: Super Contributor
timestamp: May 17, 2017, 01:21:49 am
content: Quote from: electrolust on May 17, 2017, 01:04:44 amYou might also get something out of these videos, even though some are talking about self-resonance, the theory applies to LC circuits too:

author: danadak
author_rank: Super Contributor
timestamp: May 17, 2017, 12:13:41 pm
content: Daves video might be useful -https://www.eevblog.com/2012/12/08/eevblog-396-bode-plotting-on-your-osciloscope/Regards, Dana.
measuring LDO noise with an LNA: shielding questions - Page 1
Forum section: electronics / beginners

author: exe
author_rank: Unknown
timestamp: October 15, 2019, 06:22:20 pm
content: Hi! I want to measure noise of my LDOs (just for fun). So, I want to assemble a low-noise amp that would amplify noise. My understanding is there should be a lot of shielding, preferably the whole measurement setup. Or at least LNA and cables should be shield. And I have a few question how to do it properly, or what are best practices. I have no previous experience with shielding.To some questions I found answers on the Internet, but I'd like to confirm.1) Should LNA's shield be earthed? I read conflicting opinions on this (or I misunderstood)2) Should the shield be connected to LNA's "ground"?3) Can I use BNC/SMA connectors (with single conductor inside the cable) to connect DUT or I need a cable with two conductors that are shielded? (I've seen both used)4) What if a shield consists of multiple isolated pieces of foil? If this is not ok, should I connect pieces of the shield in multiple points, or it's enough to connect it in one point?5) Are shield material and thickness important? Can I use food aluminum foil? Or copper foil be better?

author: awallin
author_rank: Frequent Contributor
timestamp: October 15, 2019, 07:34:07 pm
content: see fig6 herehttps://www.analog.com/media/en/technical-documentation/application-notes/an83f.pdf

author: ejeffrey
author_rank: Super Contributor
timestamp: October 15, 2019, 10:38:28 pm
content: What frequency range do you want to measure? Do you have an estimate of the noise density you expect? Have you chosen an LNA? What instrument are you going to use to measure the output of the LNA?Ordinary coax and BNC/SMA connectors for the appropriate bandwidth should be sufficient for most applications. Connect the coax shield to the circuit ground. Or if you are building your own circuit you just connect the regulator output to the LNA input on a PCB.

author: exe
author_rank: Unknown
timestamp: October 16, 2019, 05:31:32 pm
content: I want to measure, say 0.1Hz-10Hz and broadband noise of at least 1MHz. My "lna" is going to be just AD8428BRZ. Noise density... I dunno. It will be connected to my micsig TO1004 or analog discovery 2.

author: Zorc
author_rank: Contributor
timestamp: October 17, 2019, 09:03:45 am
content: I'm going to follow this since I plan on getting into lower noise PSU solutions as well.Probably end up needing to do some measurement myself to compare them
Measuring Op Amp Parameters - Page 1
Forum section: electronics / beginners

author: kg4arn
author_rank: Unknown
timestamp: June 09, 2013, 12:41:21 pm
content: For those of us stimulated by Fundamentals Fridays to investigate and measure Op Amp parameters,here is a paper by James Bryant of Analog Devices:Simple Op Amp Measurements, Analog Dialogue 45-05.The circuits are simple and you don't need precision resistors if you measure and match the ones that you have on hand.http://www.analog.com/library/analogdialogue/archives/45-04/op_amp_measurements.htmlIn the author's words:"the most basic dc and ac parameters can ... be measured reliably with a simple basic circuit that is easily constructed, easily understood, and remarkably free from problems"

author: fpliuzzi
author_rank: Regular Contributor
timestamp: June 09, 2013, 02:21:37 pm
content: Nice find, thanks for the link. James M. Bryant packed a lot of useful info into that three page pdf file.Regards,Frank
Measuring oscilloscope input capcity with probe calibration squarewave - Page 1
Forum section: electronics / beginners

author: Marek85
author_rank: Contributor
timestamp: May 21, 2015, 03:05:40 pm
content: Hello,I was just wondering weather I can measure the input capacity of my scope with the built in square-wave generator dedicated for probe calibration.The scope inputs are marked with: 15 pF // 1 MOhm.I assumed that I can apply the RC formula so:So the RC = 15 usNevertheless when I measure the time when the square wave reaches about 0,63 V (63 % for 1 V) I'm getting 19 ns instead of 15 us.Does it my that I cannot apply the RC formula for the scope inputs? Or maybe I am doing something else wrong?Best RegardsMarek

author: PSR B1257
author_rank: Frequent Contributor
timestamp: May 21, 2015, 03:15:52 pm
content: QuoteYes. You can not apply this formular in general to a RC-parallel circuit if you force a voltage to it. The voltage in a parallel circuit is everywhere the same. Unless you have a ass load of capacitance, you will not notice it this way.You will only see the time constant of this circuit, if youdisconnectthe voltage source, instead of switch the voltage to zero.

author: KerryW
author_rank: Regular Contributor
timestamp: May 21, 2015, 03:52:44 pm
content: Just apply the square wave through a 1 meg resistor of your own, then measure the rise (and/or fall) time. It will only go to 0.5V instead of to 1V.Edit: Don't forget to use 500K as your R in the formula
Measuring output of a pool pump VFD - Page 1
Forum section: electronics / beginners

author: ogdento
author_rank: Regular Contributor
timestamp: March 15, 2024, 05:22:35 am
content: I've got a VFD for a Pentair Superflo VS pump that takes either 120 or 240 volts (single phase) to drive a three phase motor (at 120 or 240-ish volts)... but I don't have the motor and I'd like to measure the output voltage/frequency and also see if the drive works at all.My questions are:1. My Fluke 87-3 has no VFD/LPF function so I'm assuming an ac voltage reading would be off, but I'm pretty sure a frequency reading would also be off... is that true?2. I'd like to hook up a load to test the drive... in this post (https://www.eevblog.com/forum/beginners/can-anyone-make-sense-of-this-vfd-waveform/msg3247882/#msg3247882), seanb suggested using 3 incandescent bulbs in a star (wye) configuration as a load, but my inverter only has 3 output terminals (i'm assuming the ground is a mechanical connection to the casing)... doesn't a star require a neutral? Should I use a delta configuration instead?Fyi the drive looks like this:https://bestpoolshop.com/product/pentair-superflo-vs-pump-drive-only-kcca0192-0002/Thanks for any input!

author: PSR B1257
author_rank: Frequent Contributor
timestamp: March 15, 2024, 08:26:20 am
content: QuoteWhy would the VFD not work?QuoteVery likely.QuoteStar oder delta-connection doesn't matter, it depends on the nominal voltage of the bulb. With star-connection you are on the safe side.QuoteAs every VFD.QuoteCorrect.QuoteNo. Neither with light bulbs, nor with actual motorwinding-star-connection (has to be always left isolated). This is also true for line-powered "star-loads", if they are symmetrical of course.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 15, 2024, 11:15:18 am
content: You can estimate the error for frequencies above 50Hz from the fluke manual. The 87b has an input impedance of 10M.If an lpf is needed add a simple RC section. Make sure the capacitor is "class X".If you keep R under 10k the error is very below the cut off frequency.

author: ogdento
author_rank: Regular Contributor
timestamp: March 15, 2024, 04:34:02 pm
content: Thank you both for the repliesQuoteI repair a lot of Pentair pool automation boards, and this inverter came in a box containing some damaged items so I'm just assuming there's an issue with it - there's a chance it's fine.QuoteThank you for clearing that up for me!and Terry thanks for that diagram... I was interested in making my own filter but wasn't super confident (not sure why?). I should have just built one and checked it with a signal generator and a scope first (although my 1054z has a 1M input impedance vs the Fluke's 10M). +1 for class-x caps!

author: Siwastaja
author_rank: Super Contributor
timestamp: March 15, 2024, 07:21:45 pm
content: Just get a motor. VFDs are literally not supposed to be used for anything else but drive motors. There is not much you can test, and unnecessary tests are not only waste of time because they just mislead you, they also pose a risk you do something which damages the VFD or get hurt yourself.
Measuring output voltage of H bridge inverter - Page 1
Forum section: electronics / beginners

author: JTUnger
author_rank: Newbie
timestamp: June 04, 2023, 10:13:54 pm
content: Hello everyone, first time posting. Im tring to measure the RMS output voltage of a inverter so that I can have a reference for a PI control that drives the SPWM of the H bridge. The sensor that is currently available to me is the ADS1115, I was hopeing to use the diferential voltage measurement mode to measure the rectified voltage of the inverter, but then realized that the ADS can't measure voltages that are negative referenced to the ADS's supply ground, so that idea went out the window. The output ranges in from 1Vpp to 12 Vpp, DC link is 16V but can vary depending in SOC of the bateries im using(hence why i want to imclude PI control in the output). Is there a recomended way to do this? Should I use another sensor or topology?Thanks!

author: m k
author_rank: Super Contributor
timestamp: June 12, 2023, 02:39:36 pm
content: You can use a current transformer.

author: geggi1
author_rank: Frequent Contributor
timestamp: June 12, 2023, 05:27:06 pm
content: There are chips that will do that.https://www.analog.com/media/en/technical-documentation/data-sheets/AD636.pdfIt is probably the simplest way to do this.

author: bidrohini1
author_rank: Contributor
timestamp: June 13, 2023, 11:02:52 am
content: You can get some more ideas from this paper too:https://www.researchgate.net/figure/Input-and-output-power-of-the-H-bridge-inverter-Measurement-conditions-distance-60-cm_fig2_330603737