hybridfree/eevblog-posts huggingface dataset:
Measure weight of an object that is on torque arm? - Page 1
Forum section: electronics / projects

author: tlhsglm
author_rank: Contributor
timestamp: January 24, 2021, 09:44:59 pm
content: Hi fellows,How can i get measure of the object that i dont know distance of object's center of gravity from sensor?Auxiliary picture is below. object 1 and object 2 is not putting on beam at same time, drawed just to show how far that can be;I have 1 idea like picture below but it's not good because of combining 2 load cells not recommended and gives x2 x2,5 more bad accurety.Thats mathematic is ; ( thick ones are known)load cell1 value=(object's weight) x distance1load cell2 value=(object's weight) x distance2distance2 -distance of load cells from each other= distance1Weights can be found from these equations

author: Kleinstein
author_rank: Super Contributor
timestamp: January 24, 2021, 10:15:07 pm
content: The solution is probably the way to go. Besides the 2 sensor solution, there may also be a mechanical system with leavers to separte the downward force from the torque.

author: tlhsglm
author_rank: Contributor
timestamp: January 25, 2021, 05:08:10 am
content: Quote from: Kleinstein on January 24, 2021, 10:15:07 pmCan you please give me a sample or a trace to google it?

author: Ian.M
author_rank: Super Contributor
timestamp: January 25, 2021, 05:17:39 am
content: You'd need to resolve the forces into horizontal and vertical components. A parallelogram linkage, with ball or roller bearing pivots, with its fixed bar vertical, and the beam attached to its moving vertical bar would do the job. Rest the moving vertical bar on a load cell.

author: EmmanuelFaure
author_rank: Regular Contributor
timestamp: January 26, 2021, 02:37:08 pm
content: Quote from: tlhsglm on January 24, 2021, 09:44:59 pmYour 2 load cell mechanism is the way to go. But your equations are not correct. Even dimensionnaly : "load cell1 value=(object's weight) x distance1". The left member of the equation is a force, and the right a force * a distance. The multiplicative term have to be adimensional, you have to have a force on both sides.Correct equations from the lever theory : With G = Object center of gravity. L1 = Load cell 1 (left). L2 = Load cell 2 (right). Positive sign = Force to the top.Force on the left load cell = Object weight * GL2 / L1L2Force on the right load cell = - Object weight * GL1 / L1L2And to check, F load cell left + F load cell right = Object weight. Which is correct.
Measurement Bridge 10 x kHenry ?? is that useable ? - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: March 09, 2024, 08:28:36 pm
content: I just scored this cool old unit,but look at the inductor ranges !!i mean the 3 top ranges i just cant understand,please anyone, tell me what type of inductors in that value area ?what are they used for ?See attached pictures

author: coppercone2
author_rank: Super Contributor
timestamp: March 09, 2024, 08:37:34 pm
content: Its a inductance multiplier. You need to read a bit to figure out how that works exactly, its strange. They do it with capacitors too, I think using a transformer. I don't meant a active circuit. No one actually made like 1F caps inside of those decade boxes (a super capacitor would never pass calibration stability and a stable 1F capacitor is just too damn big).for real inductorsThe largest inductor ever known to me was Fermi National Accelerator Lab's Tevatron magnet. If memory serves it was 1000 Henries running continuously at 1400 DC Amperes. Energy storage must have been right around 1 GigaJoule. They had a "quench resistor" designed to burn off the energy in case the magnet would develop an open circuit. The resistor (designed by my boss!) could be seen from space on Google Maps until not long ago.ShareCiteFollowanswered Mar 20, 2018 at 17:19Ernie Buchanan's user avatar****Signal transformers can go quite high, thanks to the extreme permeability of certain materials: permalloys and some nanocrystalline types being the most important today. The catch: you don't get much flux, so the signal level and magnetizing current are both very low.https://electronics.stackexchange.com/questions/303320/what-is-the-largest-inductance-value-ever-attained-in-henriesSignal inductors they seem to call them. But there is some method to get a higher inductance with a transformer in a calibration thing.

author: trobbins
author_rank: Frequent Contributor
timestamp: March 09, 2024, 09:57:18 pm
content: Laminated core inductors and transformers have inductance levels well into the hundreds of Henry, and into 1kH would be practical. However, for that inductance the winding is energised at many Vac, so not a low signal level. Do you know what the excitation voltage is of that instrument?

author: oz2cpu
author_rank: Frequent Contributor
timestamp: March 10, 2024, 10:48:01 am
content: I was able to find manual with specifications
Measurement of s11 of differential output antenna transmitter - Page 1
Forum section: electronics / projects

author: electronx
author_rank: Regular Contributor
timestamp: December 11, 2024, 09:43:00 pm
content: Normally, when we look at the s11 parameters from the feed point of a single-ended antenna, we can easily see the s11 reflection coefficient, yes.Now, the question I am wondering is this: I have a differential output transmitter. First, it goes to the balun (it converts the differential input to single-ended). Then, the match circuit and a monopole helical antenna. In this case, I want to observe the reflection coefficient in order to adjust the bandwidth and impedance in the same way. In this case, where should I place the ports? Can I create a mathematical equation between the ports and observe the general s11 performance? Or, will connecting the 2nd port to gnd in the balanced part of the balun give me the correct result?
Measurements on Usb Killer V3 - Page 1
Forum section: electronics / projects

author: newbadboy
author_rank: Regular Contributor
timestamp: May 17, 2017, 09:10:57 am
content: Seen a lot of talk regarding this gadget but not anyone that actually has measured on it. So have done someAnd the results are bad news!I have used a high voltage diffprobe so all amplitude values are x100 times.Measured with no load, 4ohm load and 100ohm load. Results can be seen belowBurst frequency=8HzInternal burst frequency=1kHzFalltime=260nsRisetime=4.8usPulsewidth=16,7usAmplitude=226VppAmplitude inc undershoot=348Vpp

author: newbadboy
author_rank: Regular Contributor
timestamp: May 18, 2017, 11:23:33 am
content: Apparently can Macbook pro handle this, anybody having some info on how they have solved this?
Measuring (DIY) active probe performance - Page 1
Forum section: electronics / projects

author: fozzyvis
author_rank: Regular Contributor
timestamp: January 14, 2022, 09:41:41 pm
content: I'm trying to make an active probe, based onhttps://content.instructables.com/ORIG/FQZ/1QZP/IPJTFO82/FQZ1QZPIPJTFO82.pdf. My repo is onhttps://github.com/dietervansteenwegen/FETprobe, but that does not represent the current state of my prototype as it is a work in progress.As this is my first time trying something like this, I am somewhat surprised by my measurement results as they seem rather promising. I am wondering if my measurement methods and assumptions (what I should be measuring and interpretation of the results) are correct.I'd appreciate some remarks/critisism on my thought process and/or measurements.I first tried a bode plot on my scope, which gave me the following (forgot to make a screenshot, but have this picture I made):As my scope signal generator is limited to 25MHz, I started up my old HP network analyser which goes to 1.3GHz. I'd be happy if the probe is useable up to 200MHz, which is probably way beyond any use I'll have for it.My measurement:First I normalized the reflection S11 with a short connected to the RF output (resulting in a flat line around 0dB),Then I normalized the transmission S21 by connecting the output directly to the input. With a direct cable between the two connectors, I get a flat line on 0dB.Then soldered a coax directly to the input of the active probe and connected that to the VNA output. The output of the probe connects to the input of the VNA.This gave me the following plot:What I think I see and can conclude:The measurement on the scope and VNA seem to match ok (both around -18dB at 10MHz)It seems useable from around 10MHz (can make another trace 0.3 -> 10MHz), before that, the gain is too unstable.From 10 to, say, 300MHz the gain is fairly stable around -17dB. This makes it useable in this range, as long as I do the conversion to account for the 17dB loss, correct?S21 up to 300MHz is reasonable as well, I think. I don't know what kind of numbers I should aim for. Since this is a hobby project I am happy with "decent" and mostly want to learn. I figure that since you want as little loading on your measured signal, a high reflection is what you want, correct? The higher the reflection, the higher the impedance, which is exactly what you aim for, no?Below 10MHz the transmission/gain is very low. Not sure how I'd go about improving this.It would be easier if I could get the gain to -20dB as this makes the amplitude conversion easier. I can likely doing this by playing with the supply voltage of the FET.Are my assumptions correct?
Measuring 100nA to 30mA within one range with parts for around 4$ or less?! - Page 1
Forum section: electronics / projects

author: WattSekunde
author_rank: Regular Contributor
timestamp: March 26, 2014, 10:45:31 pm
content: I found this interesting article about "Measure fluctuating currents with switching regulators" onhttp://www.elektroniknet.de/messen-testen/sonstiges/artikel/106418/. Sorry, the article is in german language but maybe google translate will help a bit.A development team from Texas Instruments working in Freising near Munich (München) come up with a nice idea. The main Idea behind it is a modified switching regulator. It regulates the output voltage by the number of fixed width pulses per time period instead of PWM. Each pulse has the same length so the amount of energy (current) output depends on the pulse frequency. Each pulse delivers the same amount of energy.I think it's a nice, simple idea.

author: dannyf
author_rank: Super Contributor
timestamp: March 27, 2014, 12:53:26 am
content: I don't think it is particularly good. It is essentially a current->frequency converter.There are issues with this approach, however. For example, the current source has to bear the output voltage of the "regulator".A similar but simpler approach would be to use the current to charge a capacitor and use another device to discharge the capacitor once its voltage exceeds a threshold (aka relaxation oscillator).

author: dannyf
author_rank: Super Contributor
timestamp: March 27, 2014, 12:54:59 am
content: Here is a simulation that shows how that can be done.It is not that useful as a measurement technique.
Measuring 4-20 mA current loop - Page 1
Forum section: electronics / projects

author: Saull
author_rank: Contributor
timestamp: January 18, 2018, 07:18:39 pm
content: Hello,On Danfoss VFD I have one analog output (4-20mA) which outputs VFD frequency. I would like to measure this output with multi meters mA range, do I need any resistor between multi meter and VFD output terminals or I can probe directly ?

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 18, 2018, 07:45:27 pm
content: Probe directly

author: LaserSteve
author_rank: Super Contributor
timestamp: January 18, 2018, 08:14:04 pm
content: If it has output short detection, probe with 150 or 270 Ohm resistor in series with meter. Otherwise probe directly.Steve

author: IanB
author_rank: Super Contributor
timestamp: January 18, 2018, 08:52:08 pm
content: Some multimeters have a 4-20 mA mode and will indicate % of scale directly.

author: bitbanger
author_rank: Regular Contributor
timestamp: January 19, 2018, 04:01:59 am
content: To add to what Steve said: the VFD should specify a maximum output load for the 4-20mA output (typ around 600ohms), so any series resistor below this spec will be fine.That said I personally have not encountered a Danfoss with short circuit monitoring on 0-20/4-20 out.
Measuring Appliance electricity useage - Page 1
Forum section: electronics / projects

author: doublecoffee
author_rank: Newbie
timestamp: August 02, 2018, 10:26:51 pm
content: Hi EEVblog forums!Coffee here with a newbie question on measuring appliance electricity usage. (kWh)This is what I'm planning to purchase to help me with that...Any other recommendations would be greatly appreciated (Preferably from Amazon.ca as I am in... Canada)https://www.amazon.ca/P3-P3IP4400-Electricity-Usage-Monitor/dp/B00009MDBU/ref=sr_1_4?s=hi&ie=UTF8&qid=1533245839&sr=1-4&keywords=Electricity+Usage+MonitorI'm planning to measure the following:*To clarify; my goal is to get an accurate reading for the kWh usage-Two air purifiers in the basement (different brands/models)-Fridge in the kitchen (considering getting a new one)-Dehumidifier in the basementCoffee~

author: sokoloff
author_rank: Super Contributor
timestamp: August 03, 2018, 01:03:21 am
content: I have two. They work great.

author: Fsck
author_rank: Super Contributor
timestamp: August 03, 2018, 01:19:43 am
content: There aren't as many options in Canada as in the states, but the kilawatt is a decent meter to be had. It's also cheap and since you don't need more functionality from a power meter, it's perfect for your needs.

author: james_s
author_rank: Super Contributor
timestamp: August 03, 2018, 03:56:21 am
content: I have a couple of those too, they work surprisingly well. Several years ago I tested one against a proper power analyzer and found it to be well within the claimed specs.

author: flynwill
author_rank: Regular Contributor
timestamp: August 03, 2018, 03:57:52 am
content: I have one of those as well. It works great.

author: coppice
author_rank: Super Contributor
timestamp: August 03, 2018, 06:42:44 am
content: There are a lot of really poor power/energy measuring gadgets, but a genuine Kill-A-Watt is pretty accurate. Normally within a percent or so.
Measuring audio signals with an oscilloscope - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: December 17, 2018, 09:02:35 am
content: I would like to test if my amplifier is clipping at certain volume levels when playing my loudspeakers however I'm having issues connecting the probes correctly. Is this because I am shorting out the signal to ground? I get nasty looking wave-forms and have already fried some resistors on my amp doing so.What am I doing wrong and how to measure this correctly?

author: capt bullshot
author_rank: Super Contributor
timestamp: December 17, 2018, 09:16:23 am
content: First, check if your amplifiers output is bridged (BTL, bridge tied load) or single ended ("-" connected to circuit GND).In the latter case, be sure to connect your scope's GND wire to the correct (GND) output pin and watch out for ground loops.In the first case, either connect your scope's GND wire to circuit ground and watch only one output pin, or use two probes and scope channels (each probe tip connected to one output pin) and set the scope to subtract these channels, or use a proper differential probe (which would be the easiest to use but most expensive option).

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: December 21, 2018, 04:23:37 pm
content: Quote from: capt bullshot on December 17, 2018, 09:16:23 amThanks for the reply.I've switched over to optical input to isolate the USB from ground loops with my scope and now I'm seeing the pure waves I was looking for.Cheers!
Measuring Capacitor Value - Page 1
Forum section: electronics / projects

author: craigfoo
author_rank: Contributor
timestamp: December 05, 2013, 06:35:45 pm
content: I'm trying to figure out the best way to measure the value of a capacitor in a circuit and if the value is out of spec, give feedback. The circuit would have some way of knowing what it's supposed to read and what the tolerance of the cap is. Would a microcontroller be best suited for this or is there a way I can do it in the analog domain?

author: alanb
author_rank: Frequent Contributor
timestamp: December 05, 2013, 09:36:43 pm
content: I don't think that you will have much success trying to measure the capacity of a capacitor when in circuit due to the effect of other circuit elements. If you just want to find the ESR there are several meters available for this that in most circumstances will give an acceptably accurate indication of the ESR. I have a small microcontroller based meter from Peak electronics and am happy with the results.

author: tszaboo
author_rank: Super Contributor
timestamp: December 06, 2013, 02:43:16 pm
content: Do you want to do this on a live circuit (eg. Power supply) or is it for a test system, periodically checking if the stuff still works?
Measuring Capacitors with an Impedance Analyser - Page 1
Forum section: electronics / projects

author: trewmac
author_rank: Newbie
timestamp: June 28, 2013, 03:30:43 am
content: Have you discovered that the impedance of your capacitor has positive phase?We're going to explore the real world behaviour of capacitors using a TE3001 analyser with a tweezer tip.Capacitors are subject to parasitic issues just like the inductors described in the previous post.Below is the measured capacitance of a 1nF 0805 X7R Ceramic chip capacitor manufactured by AVX.Once again, the low frequency response makes sense but around 107MHz the capacitance sharply rises before becoming negative!Just like inductors, capacitors have unwanted stray elements inherent in the physical construction of the component that come into effect at high frequencies.107MHz is the self resonant frequency for this capacitor and above this frequency it appears inductive.Real world capacitor modelCapacitors are constructed by layers of conductors and insulators that inherently contain resistance and inductance. They can be modelled electrically by the diagram below.R stray is often referred to on data sheets as equivalent series resistance or ESR.Low Frequency ResponseAt low frequencies (far below the self resonant frequency) the impedance of L approaches a short circuit so it can be removed from the model. Further more, the impedance of C is so large compared to R, R can also be removed.The value of C can be read straight from the LCD screen in R-L-C format. I chose to view it at 1MHz.C=1.04nFHigh frequency responseAbove the resonant frequency the impedance of C approaches a short circuit so it can be removed from the model. Further more, the impedance of L is so large compared to R, R can also be removed.Now L can be measured using the equivalent circuit format at a frequency well above the resonant frequency. I had to go all the way to 300MHz to get a reasonable impedance to measure.L=1.86nHSelf resonanceAt the self resonant frequency f, the measured reactance is zero because the reactance of the stray inductance L cancels out the reactance of the capacitance C. With L and C gone, this leaves only R.Viewed in the parallel equivalent RC chart the resistance will reach a minimum value at self resonance, and this value is R stray.Reading from the chart, R ~ 0.05 Ohms.The value offcan be taken from the location of this minimum or the zero crossing of reactance as we did before. Both ways of findingfshould yield similar values.Reading from the chart,f~ 107MHz.The same formula for self resonance that we used for the inductor model can be to test the validity of our capacitor model.This time, we rearrange the formula to get L in terms of C andf:Plugging in our values of C andf, we getNot perfect, but for our simple model it’s not far off the measured 1.86nH.So now we have a real world model that more accurately describes the high frequency behaviour of this capacitor.To summarise the technique:Just resistors to go now...
Measuring CMRR in single-supply simulation - Page 1
Forum section: electronics / projects

author: jmw
author_rank: Frequent Contributor
timestamp: March 07, 2021, 09:47:02 pm
content: In Analog Device's app note MT-042, they describe this circuit and formula for measuring CMRR:First off, is this formula right? When I solve the circuit, I get:\[v_+ = \frac{R_2}{R_1 + R_2}v_{in}\]\[v_- = \frac{R_2}{R_1 + R_2}v_{in} +\frac{R_1}{R_1 + R_2}v_{out}\]\[v_{out} = A_d(v_+ - v_-) + \frac{1}{2}A_{cm}(v_+ + v_-) = \frac{A_{cm} v_{in} \frac{R_2}{R_1+R_2}}{1 + \frac{R_1}{R_1 + R_2}(A_d - \frac{1}{2}A_{cm})}\]Under the assumption the denominator is large, the "1" drops out, and if \(A_d \gg A_{cm}\), then \(A_d - \frac{1}{2}A_{cm} \approx A_d\), so the result is\[v_{out} = \frac{v_{in}}{A_d/A_{cm}}\frac{R_2}{R_1} = \frac{v_{in}}{\mathrm{CMRR}}\frac{R_2}{R_1}\]Did I make a mistake in simplifying? They didn't show their work in the formula for the app note... Next, in doing simulations, what is right setup in a single-supply configuration? Should the input reference the virtual ground, like this:Or be AC-coupled to ground?

author: Marco
author_rank: Super Contributor
timestamp: March 07, 2021, 10:21:22 pm
content: I'm not going to run the formulas, but if R2 over R1 is large you can ignore the 1 in their formula as well.Also they meant to show the naive circuit couldn't work ... 1 ppm matching dividers don't exist outside of SPICE.

author: David Hess
author_rank: Super Contributor
timestamp: March 10, 2021, 02:13:12 am
content: It is sufficient to trim the resistance ratios but the more practical version uses another resistor between the inverting and non-inverting input to raise the noise gain.https://www.changpuak.ch/electronics/downloads/bob_pease_lab_notes_2005.pdf
Measuring CR2032 IR on an LCR meter - Page 1
Forum section: electronics / projects

author: Psi
author_rank: Super Contributor
timestamp: September 01, 2022, 10:15:32 pm
content: I tried to measure the IR of a few CR2032 using a BK Precision 880 LCR meter using the technique described here for a Keysight LCR meterhttps://edadocs.software.keysight.com/kkbopen/how-to-measure-the-internal-resistance-of-coin-cell-battery-using-e4980al-lcr-meter-620139958.htmlThe results didn't make sense, an 80% discharged CR2032 was around 15R while a 20% discharged CR2032 was 32R (Same Panasonic brand cell)I double checked the capacitor values were correct and the wiring was correct, any ideas why that circuit might not work for me.Maybe the values/technique described is somewhat matched to the circuitry inside a keysight LCR and not compatible with my LCR?The caps I used were ceramic.Test was done at 1khz on LCD, as described.Any ideas?Also, if anyone can recommend a professional battery simulator that can do CR2032's and is good, that would be cool. I expect it to cost a bit.

author: thm_w
author_rank: Super Contributor
timestamp: September 01, 2022, 11:06:57 pm
content: I tried with a 7uF PP on a new CR2032, shannon LCR tweezer:- 8 ohms at 10kHz- 22 ohms at 1kHzThere are lots of older battery simulators for reasonable price on ebay, eg keithley 2302 or similar.https://www.eevblog.com/forum/microcontrollers/power-supply-cr2032-3v-battery-drop-voltage/edit: DC short circuit ESR is around 17 ohms

author: mawyatt
author_rank: Super Contributor
timestamp: September 02, 2022, 12:36:47 pm
content: Did you perform a Short Circuit calibration with the capacitors in the measurement circuit?Here's link to a DIY LCR Meter Bias adapter that should work for measuring battery ESR.https://www.eevblog.com/forum/projects/bias-network-for-lcr-meter/msg4091638/#msg4091638Best,

author: gamalot
author_rank: Super Contributor
timestamp: September 02, 2022, 01:05:55 pm
content: I measured a Panasonic CR2032 battery with my 4338B and it was about 8 ohms.---I checked with the NF ZM2372 (with an external ZM2328 DC voltage bias adapter) and still got about 8 ohms.
Measuring cracked MLCC - Page 1
Forum section: electronics / projects

author: Manul
author_rank: Super Contributor
timestamp: October 12, 2023, 10:00:38 pm
content: Hi,Just wanted some feedback / sanity check. I believe it could be useful to others too. I have a cracked 0805 MLCC which value I want to know. Crack is just at the very end, where terminal begins.So out of interest I tried to measure it (and avoid deep analysis / guesswork).Tools: Microscope, sharp pointed needle, LCR meter, steady hands or mechanical setup.Step 1: Number of visible equaly spaced metalic layers equals 10. Roughly 45um spacing. At one particular place, where crack is the deepest, there is one in-between (11th) layer visible and it's connected to the other terminal.So based on step 1, I can say, that the type of construction is most likely of type "e" (picture below), if general proportions of these images are to be believed.Step 2: Top and bottom layers measures around 1.26nF.Step 3: Any middle layer measures around 2.43nF.So the total value should be 8 * 2.43 + 2 * 1.26 = 21.96nF. Very close to standard value of 22nF.Or more practically speaking, if number of layers is n, and measured capacitance of some middle layer is C, then:if n is even, total capacitance equals n * C - Cif n is odd, total capacitance equals n * C - C / 2So far, so good. I don't know, I guess I should feel confident that it's correct? Is it?For my own sanity check, I checked another cracked MLCC which I have. This one is 1210 100nF (known value). And here is where some confusion started.Step 1: 23 metalic layers, around 30um spacing. None of them connect to the other terminal. It's not very equaly cracked, but again, quite near termination.Step 2: Top layer measures 9.4nF, bottom layer measures 4.8nF (logical, because number of layers is odd).Step 3: Middle layers itterate: one layer around 9.5nF and one around 250-300pF.In this case it is clear that you can't just blindly measure one layer and multiply. WTF are 300pF layers and what physical construction they imply? How to aproximate total capacitance if it would be unknown?
measuring current  - Page 1
Forum section: electronics / projects

author: hpibmx
author_rank: Regular Contributor
timestamp: June 09, 2023, 02:04:32 pm
content: HiI'd like to measure both mA and A for my motherboards consumptions,so is there anyway wire both analog ammeter without burning them? I need them both as i need to monitor the startup ma and the standby consumption.thank you in advance.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 09, 2023, 02:55:13 pm
content: Combining the 2 meters is not that easy. Depending on the details of the meters it could be done by adding anti-parallel schottky diode to the mA meter to clamp the voltage / signal and than have them in series. However the voltage loss / burden voltage may still be too high for the computer to work. The probably better choice would be unsing only the shunt from the A meter and than add a custom amplification for the low range. This may than need a different meter for the low range (may use the old one by removing the shunt).

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 10, 2023, 02:49:10 pm
content: It is more common to use just one meter, and then add some circuitry to switch between different ranges. quite similar to the old analog Multimeters, that use a single pointer with many current, voltage, and resistance ranges.

author: TimFox
author_rank: Super Contributor
timestamp: June 10, 2023, 04:46:39 pm
content: Another method is to build an analog logarithmic amplifier to measure the voltage across a shunt resistor.This is not easy to build, but it is straightforward to calibrate the indicated voltage output as a function of input voltage/current.The ancient (ca. 1970) -hp- 7562A and 7563A logarithmic units can be found at surplus sites: the 7562A includes a true-RMS converter, and is capable of AC or DC input. The 7563A is DC only.The 7563A has a dynamic range of 110 dB (3.2 x 105V/V), and a rise time of 2 ms (input < 1 mV) decreasing to 40 us (input > 10 mV) and 2 us (input > 1 V).It has a single input range, but you need to select positive or negative input voltage.
Measuring current and voltage phase difference. - Page 1
Forum section: electronics / projects

author: Gibson486
author_rank: Frequent Contributor
timestamp: April 30, 2020, 02:07:15 am
content: I have this load that is completely capacitive, but I want to see how the current and voltage phase changes as the load changes. I would use a current probe, but everything is on a pcb, so there is no wire to wrap around. Any ideas on how I can measure this?

author: SilverSolder
author_rank: Super Contributor
timestamp: April 30, 2020, 02:18:02 am
content: Quote from: Gibson486 on April 30, 2020, 02:07:15 amHall effect sensor?

author: jbb
author_rank: Super Contributor
timestamp: April 30, 2020, 07:41:44 am
content: The classic method is to cut a track and solder on a little loop of wire to clip onto.If you can’t do that and there isn’t much room, the AIM TTI iProber can directly measure current in a trace. It’s helpful, but very susceptible to external magnetic fields (eg you get DC offset from your steel table leg) and the gain varies with how you hold it.
Measuring current with a microcontroller - Page 1
Forum section: electronics / projects

author: samu1214
author_rank: Contributor
timestamp: May 24, 2023, 03:36:27 pm
content: Hi!I'm doing a project that involves sensing current. I'm charging a battery and I need to control how much current and voltage I'm giving out.I thought that it would be okay to use an SCR like a 40tps controlled by an MOC3021 optocoupler.The part I have doubts about: I know because of common-mode voltage that current with a shunt and a simple operational amplifier has to be measured at the low side of the battery ( - ).I saw a lot of circuits that are especially made for sensing the current with a external shunt, but do I need this if I'm okay with an error of about 3%? I want to measure around 30 A max and 1 A min. I saw some shunts of 0.5 mΩ and 9 W; that will be fine.I have a lot of trouble to find and understand the dedicated amplifiers for that. Could you suggest a circuit with an LM358 for instance that will be good for my requirements or do I need a dedicated one?Edit: I saw that the LM358 has an input offset of 2mV, and if i have 1Amp trough the SHUNT it will be 1mV, so its not enough... I saw something about the ACS711, what do you think about?Thanks!

author: rstofer
author_rank: Super Contributor
timestamp: May 24, 2023, 04:23:26 pm
content: I would be looking into High Side Current Sense Amplifiers. There are many...Here is a sample returned by Google:https://www.mouser.com/new/stmicroelectronics/stm-tsc101-amplifier

author: Simon
author_rank: Unknown
timestamp: May 25, 2023, 12:51:16 pm
content: https://www.eevblog.com/forum/microcontrollers/measuring-current-with-a-microcontroller-378422/msg4878029/#msg4878029
Measuring Differential Trace Impedance with 2 port vna - Page 1
Forum section: electronics / projects

author: electronx
author_rank: Regular Contributor
timestamp: December 03, 2024, 10:54:11 am
content: yes this is the question .I'm surprised it hasn't been asked beforeI want to measure trace impedance with a 2 port vna. I am thinking of designing a demo board for this. It will be connected with smd sma connectors. The differential lines I want to measure are 90 and 100 ohm. What kind of termination should I use for this?I think I can extract it with mixed mode syz parameters.

author: virtualparticles
author_rank: Regular Contributor
timestamp: December 03, 2024, 08:39:39 pm
content: There are some interesting things you can do with this. If you terminate the far end with 50 ohms loads and attach ports 1 and 2 to one side, you can calculate differential S11 from SDD11 = (S11+S22-S12-S21)/2. You can then switch to time domain and measure return loss vs time/distance. If you don't have time domain on your VNA, you can use SciKit-RF to do the calculations for you in Python. You can calculate all differential parameters by performing a full 4-Port measurement, 2-ports at a time, with other ports terminated. See the attachment.

author: electronx
author_rank: Regular Contributor
timestamp: December 03, 2024, 09:14:01 pm
content: thanks for your feedback.Is it possible to provide a simple visual about the termination you mentioned?

author: virtualparticles
author_rank: Regular Contributor
timestamp: December 04, 2024, 01:26:32 pm
content: Sure, here is a measurement setup of a differential line with the port numbers annotated. It's a four-port measurement with a two-port VNA, so pretty tedious. Connectors on the test board are female SMA and the cables are male SMA. I used 50 ohm male terminators on any port that was not connected to the VNA, which is required. The way I numbered the ports on the board match the article I attached earlier for calculating the differential parameters.I'm using a 9 GHz VNA from Copper Mountain Technologies here. This one is extendable to 330 GHz if needed.I should mention another thing. You have ground on each side of the traces. If you don't have stitching vias attaching top ground to bottom ground, those two ground planes will resonate and take a big bite out of the trace response.
measuring distance accurately with a small cone angle - Page 1
Forum section: electronics / projects

author: Etesla
author_rank: Regular Contributor
timestamp: September 16, 2020, 08:04:28 pm
content: Hi all. I am trying to find a distance sensor with the following specifications:Minimum sensing distance of around 10 cm or betterMaximum sensing distance of around 50 cm or betterdistance measured within +- 3mmA total cone angle of less than 10 degreesA price under $10Works to measure the distance regardless of the target material type, as long as its solid.The ideal version of this sensor would be a laser where the distance from the laser diode to the laser point was measured accurately.Here's what I have learned already:the standard HC-SR04 ultrasonic sensor unfortunately won't work because the cone angle is too largeThe best TOF sensor I have found is the VL53L0X variety sensor made by ST, but still, these have cone angles that are too largeThe generic analog infrared type sensor also has a cone angle that is too large, and has different characteristics depending on the target material.Does anyone have recommendations for a sensor or sensing method that meets most or all of these specifications? Thank you!EDIT: I found these things. Anyone know what kind of sensor they use or if they really do have a 'laser width' kind of a cone angle?https://www.lowes.com/pd/Bosch-BLAZE-65-ft-Indoor-Outdoor-Laser-Distance-Measurer-with-Backlit-Display/1000102525?cm_mmc=shp-_-c-_-prd-_-tol-_-google-_-lia-_-216-_-measuringtools-_-1000102525-_-0&placeholder=null&gclid=CjwKCAjw74b7BRA_EiwAF8yHFEVO0ojza_dOgTrxk4W9fadVzYwLVgtlYUT7jvbRUZFpSTOtMTfUDBoCzxEQAvD_BwE&gclsrc=aw.ds

author: TheMG
author_rank: Frequent Contributor
timestamp: September 17, 2020, 02:09:22 am
content: For $10... you're most likely not going to find anything.Here's one that I think meets your requirements (other than cost):https://www.digikey.ca/en/products/detail/banner-engineering-corporation/Q4XTBLAF500-Q8/10652392You can probably find cheaper than this if you do some research, but I don't think $10 is going to happen.Quote from: Etesla on September 16, 2020, 08:04:28 pmThese devices (at least any of the ones I've seen), don't use an off-the-shelf sensor. They have a separate laser diode and sensor with custom designed optics and circuitry.But as far as the sensing "cone" angle, yes, it really is just the size of the laser dot (the same laser typically serves dual-duty, as both a visual aiming aid, and also to perform the actual measurement).
Measuring inductance-LCR meter,Bridge or DMM adaptor? - Page 1
Forum section: electronics / projects

author: djsb
author_rank: Super Contributor
timestamp: March 12, 2010, 11:21:04 pm
content: Hi,Does anyone have any ideas for a simple but accurate way of measuring coil inductance? Is there a circuit I can build that can work with a multimeter?Thanks.David.

author: rossmoffett
author_rank: Regular Contributor
timestamp: March 12, 2010, 11:28:12 pm
content: There are DIY circuits around if you search, I just bought a $20USD LCR meter from eBay a couple of years ago.There are several circuits you could build that you could measure with your meter, they're basically LCR meters with no display.

author: Zad
author_rank: Super Contributor
timestamp: March 13, 2010, 01:12:27 am
content: It depends on how many you have to do, how precise you want it, and the approximate value.If you have an oscilloscope, make a parallel resonant circuit with a known capacitor, pulse a low voltage across it and measure the frequency of the sine wave it produces. f=1/(2*pi* sqrt (L*C) ) and rearrange to get the value of L.

author: joelby
author_rank: Frequent Contributor
timestamp: March 14, 2010, 11:42:13 am
content: There are plenty of standalone LC meter kits around - you could probably build you own from spare bits. Here's one available in kit form, but the page also has information on the calculations involved:http://www.rfcandy.biz/communication/imp_lc.html

author: Rowland
author_rank: Newbie
timestamp: March 19, 2010, 07:49:59 pm
content: Take a look at the ALMOST ALL DIGITAL ELECTRONICS (AADE) website. The L/C IIb meterhttp://www.aade.com/I have had my meter for the last 10 years and it is invaluable.Neil has a lot of data about the kit on the site.The kit is full, in that it comes with an enclosure and can easily be built in an eveningRegardsRowland

author: jimmc
author_rank: Frequent Contributor
timestamp: March 20, 2010, 11:10:59 am
content: If you're building from scratch, you can simplify the circuit (and loose the LM311) by switching to the PIC16F628 seehttp://ironbark.bendigo.latrobe.edu.au/~rice/lc/index2.htmlJim

author: joelby
author_rank: Frequent Contributor
timestamp: March 21, 2010, 12:33:36 pm
content: I can also recommend the AADE meter. The only thing is that it is quite expensive! But well worth it, really - especially with the optional SMD clip.
Measuring inductance of powdered iron toroid - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: June 16, 2016, 01:18:38 am
content: I have several powdered iron toroids that I need to identify. One I think is 220uH according to the manufacturer. I don't have an LCR meter so I thought I might just put a cap in parallel and apply an oscillator and see what frequency it resonates at. Is this really suitable or would the inductance be specified with a certain amount of DC current bias? If so, what would the error be? Just a bit off or totally way out?
Measuring integrated passive components - Page 1
Forum section: electronics / projects

author: Jolle
author_rank: Contributor
timestamp: June 10, 2014, 11:05:42 am
content: I am doing a project at my university where i look at components for DC/DC converters operating at frequencies where the passive components can be implemented inside the chip.I have no experince with this type of components so my calculations is based purely on different articles about the topic (so far i have been looking at the inductors, where I have used the modified wheeler formula for calculating the inductance and the paper "A physical model for planar spiral inductors on silicon" to find inductor parameters including Q).I will probably not be able to make a final design and get some components on a chip, but if I could do that how would it be possible to meassure say the inductance of a spiral inductor? If I just connect the inductor to two terminals I would expect the meassured inductance to be wrong because of the added inductance/capacitance by the connections from terminals to the designed inductor. So is there a smart way to do this?I have tried to search the internet about this but could not find anything, so I was hoping someone here at this forum could point me in a direction where I can read something about this topic

author: Rerouter
author_rank: Super Contributor
timestamp: June 10, 2014, 11:13:25 am
content: though i am also not from this field, i would assume the best way would be to work out what your material of choice is (silicon is not just silicon), as this will tell you a few of the properties you can use to figure out what non ideal characteristics your inductor has,next up would be the process, each one likely has different layer thicknesses and ways of doing inductors this would be what would tell you your ideal value,dave recently did a review on some silicon slides, the man that offered him them works in that industry, and in response to that video wrote up quite a few long and detailed posts on the matter, if no one else has helped by tomorrow I'll try and dig up the links (sorry horrible with names)
Measuring Internal Resistance in Large Electrolytic Capacitors - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 06, 2021, 01:08:32 pm
content: i have been working quite a while with this topic,I try to explain a method i came up with, where it is possible to measure very low mili ohmsin large caps.I explain it in detail herehttps://youtu.be/M4eMLfFe_0wi hope you like it, maybe you can use this information,you are also very welcome to comment, if you found a better, easier, cheaper, more accurate way.

author: jwet
author_rank: Frequent Contributor
timestamp: December 11, 2021, 03:49:17 am
content: This is well thought out and interesting. There may be one missing element though- capacitor ESR is a frequency dependent parameter. Your slow rise and fall narrow pulse measurement scheme is getting the ESR at a frequency related to your rise time and your pulse rate- a pretty low frequency. You might consider using a strong drive for the switched FET and drive it at frequencies varying from 100Hz to 1 Mhz. This is really the important ESR measurement for capacitors used in switching power supplies etc. If your interest is just in bulk ESR at 120 Hz like in a standard transformer 60 Hz supply with full wave bridge, your method will work fine. Often I'm looking for the ESR at 100 Khz or higher for example. There are some high value capacitors that really excel at this like Panasonic OS-Con's- 10 of milliohms, HF electrolytics 100 milliohms and finally regular aluminum electrolytics at fraction of ohms. These days, its common to parallel a decent HF electrolytic with a high value ceramic of perhaps 10% of the value to get a good HF cap. Old electrolytics had very poor ESR at any frequency above 120 Hz.
Measuring Jitter on LVDS Clock Signals? - Page 1
Forum section: electronics / projects

author: bhj99
author_rank: Contributor
timestamp: October 28, 2023, 07:48:32 pm
content: Hi all, I am trying to measure random and deterministic jitter on LVDS clock signals using an oscilloscope on a board design that features the TI LMK04832 clock generator chip. Are there resources or videos available that can show an example of this? The video demos I can find are aimed at measuring jitter on serial data. Or if anyone has experience with this and would like to share that would be greatly appreciated!

author: Terry Bites
author_rank: Super Contributor
timestamp: October 29, 2023, 05:40:00 pm
content: The same method applies. Stack up a load of sweeps and get the cursors onto it.It depends on your scope, many have stat functions that will deliver direct.
Measuring Jitter - Page 1
Forum section: electronics / projects

author: colorado.rob
author_rank: Frequent Contributor
timestamp: July 23, 2019, 04:01:50 pm
content: I am trying to measure the jitter of two digital signals. I am measuring the period and capturing statistics as suggested here:https://www.eevblog.com/forum/projects/is-my-jitter-measurement-method-correct/msg2299848/#msg2299848The problem I am facing is that the statistics vary considerably, and especially when changing the time base on the 'scope. I've tried enabling gating of the measurement and changing the gate period. I cannot get a consistent result. This is with a Siglent SDS2204X, using 2 channels (1&3) to get maximum accuracy, 2Gsps. I am measuring a 28MHz signal and expecting to measure jitter in the 1.2ns to 200ps range.Why does the jitter measurement vary so much based on the timebase? What additional information would be helpful in diagnosing this and allowing me to get an accurate measurement of jitter?

author: Kleinstein
author_rank: Super Contributor
timestamp: July 23, 2019, 04:21:00 pm
content: The time base can effect the scopes own jitter. Depending on the method used the trigger uncertainty can be quite a problem with the measurement. So it really depends on the detail of the implementation in the scope and how the measurement is made.Also the type of signal can be important - a 28 MHz sine wave is different from a square wave.

author: colorado.rob
author_rank: Frequent Contributor
timestamp: July 23, 2019, 05:05:24 pm
content: Thanks. This is an attempt to measure two square waves generated by a Xilinx 7z020 using LVCMOS33 signalling into a PMOD port. I suspect I need to work on proper termination to clean up the signal being measured.One signal is a noisy fractionally divided signal. This is fed back into a PLL on the FPGA.. The other signal is the output from the PLL. The first has a jitter of at least 1.25ns as it is being generated by an 800Msps SERDES output. The seconds has jitter which I suspect is about 200ps. The signal that has the widest variance is the one with at least 1.25ns jitter. It sometimes shows as low as 250ps, which is clearly not correct when viewing the trace on the scope. This makes me suspect both measurements.
Measuring Led Driver electrical efficiency. - Page 1
Forum section: electronics / projects

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: July 26, 2012, 01:17:07 pm
content: Just wondering what is the best way to measure the steady state electrical efficiency of a low voltage Led Driver.I haven't got a programmable load.I am assuming all the waveforms (Vin, Iin, Vout, Iout) are not going to be either pure dc or a low frequency AC sinusoid.Vin should be solid in this case at 24v.Assuming Iin, Vout and Iout have a non zero AC component as well as the DC component. The switching frequency on the Driver is around 100khz.What would be a good way to measure the efficiency.1% accuracy would be nice, but I doubt I could get that off my cro anyway.I have 2 meters a Fluke and a BK prescision, and an old HP 1742a scope and another old 20mhz analogue Cro.I can get access to a couple more cheap meters to, if that would help.I was thinking of just capturing all the non pure dc waveforms and multiplying them out to give both Input and Output power as a function of time.Then I was thinking of averaging these values.Anyone got a better idea

author: Rufus
author_rank: Super Contributor
timestamp: July 26, 2012, 02:08:01 pm
content: Quote from: HackedFridgeMagnet on July 26, 2012, 01:17:07 pmIf the voltage is constant average power is proportional to average current.The voltage across the LED should be reasonably constant and if it isn't you may be able to parallel some capacitance to make it so (probably giving a small artificial increase in efficiency).A difficulty is voltage burden measuring the currents. Input is easy just measure input voltage after the meter and if there is voltage ripple stick a capacitor on it. For the output if the driver has a current sense resistor measure the voltage across it and possibly find some way to calibrate it first.Accurate efficiency measurement is difficult and the higher the efficiency the harder it gets.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: July 27, 2012, 02:29:33 am
content: Thanks Rufus.QuoteI might switch to a resistive load for the measurements to make this the case.I was thinking about using a known purely resistive load. I need about 10watts, 1 amp. And accurately measure it's resistance near the operating point of the test.Then use a kelvin connection( I think that is what it is called) to my multimeter via a low pass filter and measure on DC volts. this should give me the average output power. V2/R.Then there is only the input current, I haven't looked at this waveform, maybe I can make some other assumptions here.