hybridfree/eevblog-posts huggingface dataset:
Measuring power consumption of dual supply circuit - Page 1
Forum section: electronics / beginners

author: jram112
author_rank: Contributor
timestamp: December 07, 2012, 08:03:32 am
content: I want to measure the power consumption of my opamp circuit. I understand for a single supply circuit that I can take the supply voltage, measure the current, and then compute the power. However, for a dual supply circuit there are two supply voltages. Should I measure the power from both the positive and negative supply then add them together? Should I measure them simultaneously, etc?Also, I have the EEVblog uCurrent. Should I be concerned with the virtual ground being connected to the current input terminals?Thanks

author: Zero999
author_rank: Super Contributor
timestamp: December 07, 2012, 01:50:58 pm
content: To compute the power, you need to measure two currents and two voltages. It doesn't matter whether you measure the +V to -V and +V to 0V or -V to 0V, just as long as you have two voltage and two current measurements. Look at the Ohm's law formula and you'll see what I mean.
Measuring PWM with current probe - Page 1
Forum section: electronics / beginners

author: raff5184
author_rank: Regular Contributor
timestamp: April 24, 2020, 01:16:04 am
content: Hi,I have a simple circuit: a signal generator closed on a resistor. The signal is a PWM with pulses of 60us. I'm trying to measure the current through the load with a current probe (Tektronix CT6). The load voltage is the green, the yellow is the current.Can someone please explain why I can't see the current?Is it just like that or is it a limitation of the probe?

author: 16bitanalogue
author_rank: Regular Contributor
timestamp: April 24, 2020, 01:24:32 am
content: I have never used the CT6; rather, I have always used the TCP202 current probe from Tek.I suspect, the CT6 cannot measure DC since you are getting the step and release response only.

author: raff5184
author_rank: Regular Contributor
timestamp: April 24, 2020, 01:33:20 am
content: exactly it can't measure DC. But since the frequency of my signal was high enough I thought I could measure short pulses.can the TCP202 measure square pulses or DC?

author: Manul
author_rank: Super Contributor
timestamp: April 24, 2020, 01:35:55 am
content: It has high atenuation below 200khz.But looking at typical response curve and your waveform it looks suspicious. It seems that atenuation should not be as high as it is.

author: Manul
author_rank: Super Contributor
timestamp: April 24, 2020, 01:40:14 am
content: If you do FFT on your current waveform, how it looks? Should give an insight about actual bandwidth to compare with datasheet.

author: raff5184
author_rank: Regular Contributor
timestamp: April 24, 2020, 01:57:05 am
content: Quote from: Manul on April 24, 2020, 01:40:14 amyeah the FFT of the voltage signal has a peak at 240kHz and then it goes down like exponentially

author: Manul
author_rank: Super Contributor
timestamp: April 24, 2020, 02:02:58 am
content: And what is spectrum of these spikes from current probe?

author: WattsThat
author_rank: Frequent Contributor
timestamp: April 24, 2020, 02:09:57 am
content: Scope $5000.RF current probe $1000.Knowing how to interpret what you see, pricelessSorry, couldn’t help myself as I have committed at least two of the seven deadly sins over that scope. Lust and envy.PS: probe is spot on, rolls off below 250 KHz. Yup, in spec.

author: raff5184
author_rank: Regular Contributor
timestamp: April 24, 2020, 02:23:49 am
content: Quote from: Manul on April 24, 2020, 02:02:58 ama peak at around 6MHz (and then decays) which is in the range of the probe.Indeed if I increase the frequency of the PWM the current probe can measure it
Measuring Resistance of a Real World Circuit With a Meter - Page 1
Forum section: electronics / beginners

author: PsychedelicBreakfast
author_rank: Contributor
timestamp: October 13, 2012, 06:29:38 pm
content: Yesterday, for the first time, I soldered a PCB using a metal stencil + diy toaster oven. It turned out really great, the joints look super nice. Before powering it up, I decided to measure the resistance of the 3.3V rail incase there was a short circuit. The meter measured 50 Ohms and I thought this was a bit low - I was expecting a value in kOhms. So I tried thinking and inspecting the circuit but couldn't find any fault whatsoever. So I powered it on, cautiously, and noticed that the current draw was 20 mA. This means that the input resistance is 165 Ohms but the meter reads 50 Ohms. Why this discrepancy?The circuit looks OK now - it's really just two CPLDs and a uC, all of which are unprogrammed so far. It does have quite a few schottky diodes but they all normally reverse biased. The leakage current is of these, combined, is around 2 mA. There's a LED which consumes around 7 mA.Another weird thing I found was that I got a reading of 50 Ohms if the positive lead was at 3.3V and negative lead was connected to Ground. If I reverse the connections, I get a reading of just 30 Ohms. Why is this so?

author: IanB
author_rank: Super Contributor
timestamp: October 13, 2012, 07:38:07 pm
content: Your circuit is not passive or linear (in other words, it does not obey Ohm's Law). The amount of current it will draw will depend on the polarity and on the magnitude of the applied voltage. This means it will appear to have different "resistances" according to how you test it.
measuring resistance of resister after it's soldered to PCB board  - Page 1
Forum section: electronics / beginners

author: helmet
author_rank: Newbie
timestamp: July 11, 2019, 02:22:43 am
content: This is my first electronics kit project: the Noise Toasterhttp://musicfromouterspace.com/index.php?MAINTAB=SYNTHDIY&PROJARG=NOISETOASTER/NOISETOASTER.php&CATPARTNO=NOISETOASTERPCBI bought the kit, which includes the PCB board and all of the components. I believe that I followed the instructions correctly when soldering the components (see the attachments). The instructions have tests to complete to make sure that everything is working, and some of the tests are failing. Im following some of the troubleshooting tips, but they havent really helped. Now Im taking my multimeter and measuring the resistance of all of the resistors installed on the PCB board. Most of the soldered resisters show the same resistance as before they were soldered. For instance, a 1M Ohm resister measures 1M Ohm resistance before soldering it to the PCB and after soldering it to the PCB it still measures 1M. But some soldered resisters do not show the same resistance as before they were soldered. For instance, a 100K resister shows 100K resistance before soldering, but 33K resistance after soldering it to the board. I have removed one resister on the board and replaced it twice with a new one. For instance, the 100K resister is soldered to the PCB, but only shows 33K resistance after being soldered. I removed this resister and replaced it with another new 100K resister, and it still shows 33K after soldering. Have I damaged the PCB board? Do I just not know how to measure the resistance of a resister after its soldered to a PCB board? (see attachment) thanks!

author: Shock
author_rank: Super Contributor
timestamp: July 11, 2019, 02:29:39 am
content: This is quite normal, for measuring components in circuit if you get an unexpected measurement assume there is at least one or more components in parallel. So to get around this lift one of the component legs or completely remove it from circuit to measure it out of circuit.

author: chancs
author_rank: Contributor
timestamp: July 11, 2019, 03:00:36 am
content: Resistors aren't that easy to damage. Instead of checking their value, I would go through all the active components, making sure they have the correct part number. Also, double check and see if you have soldered all the joints.

author: austfox
author_rank: Regular Contributor
timestamp: July 11, 2019, 04:25:55 am
content: From the overlay the resistor directly below X16 and X20 should be 75K, but it looks like you have a 10K in there.

author: ArthurDent
author_rank: Super Contributor
timestamp: July 11, 2019, 01:48:20 pm
content: That definitely is a 10K not a 75K, plus it has been damaged.From the looks of some of the solder joints it looks like the joints weren't heated enough to let the solder flow smoothly and there are globs of solder just sitting on some pads and some component leads look dry. You may have bad solder connection in several areas.
Measuring Resistance with ADC & Voltage Divider, Known Resistor = R1 or R2? - Page 1
Forum section: electronics / beginners

author: evglabs
author_rank: Contributor
timestamp: November 03, 2019, 05:26:08 pm
content: When measuring resistance with and ADC on a micro and voltage divider does it matter if the known resistor is connected to the positive rail or GND?Thanks

author: schmitt trigger
author_rank: Super Contributor
timestamp: November 03, 2019, 05:46:32 pm
content: If I understand correctly what you are asking is:When solving a resistive divider equation, does it matter if I select R1 and solve for R2, or do I select R2 and solve for R1?And also arbitrarily, R1 is the leg that goes to ground, and R2 is the leg going to the voltage being measured.Short answer, it depends. It depends what you want to optimize.For instance, let's say you want to measure a voltage, loading it with no less than 1 Meg.In this case, it makes sense to start with R2 = 1 Meg and solve for R1. The equivalent resistance will be larger than 1 Meg.On the other hand, the ADC's datasheet requests that the source impedance be no larger than 10k, then you select R1 = 10k and solve for R2. The equivalent resistance will be now lower than 10k.Like everything else, there are tradeoffs, and you will find yourself re-calculating the original divider thru several iterations.In this instance, Excell or any other spreadsheet is your best friend.

author: evglabs
author_rank: Contributor
timestamp: November 03, 2019, 05:51:25 pm
content: Yeah, thanks.So, basically other than something like the ADC requirements (or in an ideal situation), it wouldn't matter if I'm solving for R1 or R2 right?

author: ogden
author_rank: Super Contributor
timestamp: November 03, 2019, 06:51:16 pm
content: Quote from: schmitt trigger on November 03, 2019, 05:46:32 pmNot true. There are many ADC's that will happily accept higher than 10k source impedance. Especially those with built-in buffer amplifier. If you are ready to slow sampling speed down, you can increase signal source impedance. Even then you can "fix" problem by adding capacitor. Signal source impedance table for 12-bit stm32 SAR (unbuffered) ADC.

author: schmitt trigger
author_rank: Super Contributor
timestamp: November 03, 2019, 10:59:54 pm
content: I used 10k(max) ONLY an example.
Measuring Sense Resistor On Current Source  - Page 1
Forum section: electronics / beginners

author: Instro_Spark
author_rank: Contributor
timestamp: March 16, 2014, 07:54:28 am
content: Hey dudes was hoping someone can point me in the right direction i've attached a PDF with my schematic.As the title says i'm trying to measure the volt drop across a sense resistor (R10 in schematic) which produces a 2.048VD when its drawing 4mA and 10.24 when at 20mASo how would i go actually measuring this VD then scaling this to range which can be feed to a microcontroller.Any ideas to improve this circuit is always welcome im learning just a bit more day by day so cool.

author: Strada916
author_rank: Frequent Contributor
timestamp: March 16, 2014, 09:06:27 am
content: Voltage divider. Simply put a 1M pot across the 512R resistor and use the wiper as input to the mirco. Adjust pot until you get 5V or 4.096 at 20mA. The 1M pot will effect the total 512R resistor by about 0.3R ohms law 1/((1/512R)+(1/1M)) = 511.7R

author: Instro_Spark
author_rank: Contributor
timestamp: March 16, 2014, 09:39:34 am
content: cheers for the response mate sounds easy enough since i have a spare opamp is there a way to use this to measure r sense resistor

author: Psi
author_rank: Super Contributor
timestamp: March 16, 2014, 09:48:37 am
content: You could use the voltage divider (as said above) and feed that signal into your spare opamp configured as a buffer.This will convert the high impedance voltage divider signal into something within spec of your MCU's ADC input impedance (usually they expect 10k or less for full resolution).

author: Instro_Spark
author_rank: Contributor
timestamp: March 16, 2014, 10:09:47 am
content: Awesome thanks for your input fellas all the best

author: Instro_Spark
author_rank: Contributor
timestamp: March 16, 2014, 01:08:27 pm
content: actually another question would i be able to get away with not using the second op amp from the left thats config as a voltage follower its going from a low impedance output into a high impedance input or am i way of the mark

author: Psi
author_rank: Super Contributor
timestamp: March 16, 2014, 11:43:30 pm
content: yep, it's not doing anythingYou already have a low impedance source from the opamp before it, so it isn't doing anything.

author: Instro_Spark
author_rank: Contributor
timestamp: March 17, 2014, 06:28:58 am
content: awesome haha sorry another question when setting up gain for your op amp are you better of using higher value resister at the moment im using 10k and 2.5k but i could also use 40k and 10k to get the same gain im guessing that with lower values there would be more current to flow but does using higher value resisters introduce any noise issues
Measuring series circuits with multimeter - Page 1
Forum section: electronics / beginners

author: stolevole
author_rank: Newbie
timestamp: April 27, 2019, 02:27:02 am
content: So this might seem like ultra newbie question but i really dont get it. If i connect multimeter in series with potentiometer for example and close circuit with multimeter and then turn potentiometer would i get right reading on multimeter? I know voltage in series is proportional to resistance of each resistor but it confuses me why i always get reading of source voltage when i connect multimeter this way(i tried with ac and light bulb dimming potentiometer).Is it different for dc? Shouldnt multimeter get low voltage reading since it has low resistance? I would very appreciate any help.

author: cs.dk
author_rank: Unknown
timestamp: April 27, 2019, 08:36:49 am
content: If im understanding you correct, you are connecting your meters input impedance ~10 meg ohm in series with your circuit.You can only use your multimeter in series when measuring current. Voltage are measured parallel.

author: iMo
author_rank: Super Contributor
timestamp: April 27, 2019, 09:23:17 am
content: If your potentiometer (wired as a rheostat) is, say 1kohm, and it is wired in series with the internal resistance of the DMM (say 10Mohm = 10000k), and with series with a 10V source for example, the voltages you read for both end positions of the wiper will be:V1 = 10V * (10000k/(1k+10000k)) = 9.999VV2 = 10V * (10000k/(0k+10000k)) = 10.000VWith a 100kohm potentiometer:V1 = 10V * (10000k/(100k+10000k)) = 9.901VV2 = 10V * (10000k/( 0k+10000k)) = 10.000VWith a 10Mohm potentiometer:V1 = 10V * (10000k/(10000k+10000k)) = 5.000VV2 = 10V * (10000k/( 0k+10000k)) = 10.000V

author: stolevole
author_rank: Newbie
timestamp: April 27, 2019, 05:05:09 pm
content: So DMM actualy has high resistance and thats why it gets all the voltage.But why potentiometer gives voltage even when its off is that because there is no perfect insulator? Thank you for clearing this up.

author: Nerull
author_rank: Frequent Contributor
timestamp: April 27, 2019, 06:52:13 pm
content: Typical potentiometers don't turn 'off', their resistance between the wiper and one of the terminals varies between the rated resistance of the pot (10k, for example) and zero (or as close to it as the materials allow).In the circuit posted by imo above, the pot would have a maximum resistance of 1k when turned in one direction, and would approach a dead short in the other direction. It has no 'off' position.
Measuring space vector PMW signal with oscilloscope - Page 1
Forum section: electronics / beginners

author: mike buba
author_rank: Contributor
timestamp: July 07, 2018, 11:43:49 am
content: Hi!Is it possible to measure space vector PWM signal and "freeze" them, but with Sweep = Auto/Normal? How to set up the oscilloscope to do that? I have Rigol DS1054... For not I have to press Single button every time (or Sweep = Single) if I want to "freeze" picture?If I am measuring dc/dc converter pulses there is no problem (signal is not moving even with Sweep = Auto/Normal). But for this signal, the width of the pulse is not constant and changes.

author: JS
author_rank: Frequent Contributor
timestamp: July 07, 2018, 02:08:19 pm
content: I'm not sure what you are asking, if the signal is changing the picture should be changing while using auto or normal triggering, and make a single snapshot with single trigger. The only thibg I can suggest if you want to stop an auto or normal display to look at it for a while isbto press the stop button. There's also the optional record mode in the 1054z, when you can capture a lot of snapshots and look at them later.JS

author: rstofer
author_rank: Super Contributor
timestamp: July 07, 2018, 03:55:23 pm
content: There should be no problem triggering on the rising edge of the signal. That part should be easy. What isn't easy is triggering on the beginning of the pattern. Perhaps the pulse width is a minimum, rising to a maximum and diminishing to a minimum and you want to trigger at the beginning of the cycle.I don't know how you are timing your PWM but if I were doing something like that with a microcontroller, I would generate a trigger pulse with one of the IO pins.Chapter 5 (page 5-8) in the User Manual talks about triggering on a pulse of a certain minimum width. So, presumably, you can trigger on the wide pulse in the sequence and then move the image around to get the first pulse on the left edge.In fact, spend some quality time with Chapter 5. The DS1054Z, like most DSOs, has an enormous number of trigger options.
Measuring standalone 12V 40Ah battery - ESP32 ? - Page 1
Forum section: electronics / beginners

author: Oleander
author_rank: Contributor
timestamp: January 14, 2021, 01:46:01 pm
content: Hello,I am about to design a little PCB module with Bluetooth. This will be permanently connected to a 12V 40Ah battery in rural areas.The goal is to enable voltage measurement of the battery using Android phone without touching the battery and module.Also, the power consumption of the module must be very low - to enable a month or longer job without charging the battery at all.What module (ESP32 ?) will fit my goal best ?

author: m k
author_rank: Super Contributor
timestamp: January 17, 2021, 12:01:22 pm
content: Why not something else?

author: mikerj
author_rank: Super Contributor
timestamp: January 17, 2021, 01:24:18 pm
content: You can buy aready made unitto do this which isn't very expensive.If you really want to do this yourself then ESP32 is probably one of the easiest solutions.

author: Oleander
author_rank: Contributor
timestamp: January 21, 2021, 10:13:14 am
content: Thanks for the suggestion !
measuring strobe light high voltage for bear deterent - Page 1
Forum section: electronics / beginners

author: superUnknown
author_rank: Regular Contributor
timestamp: May 11, 2014, 05:07:16 pm
content: I'm wondering how to go about measuring/confirming the high voltage ingition pulse on a vehicle strobe light. It's one of those amber construction vehicle flashers. I want to install a couple of electrodes on the lid of our garbage bin to keep the local bear from getting shot.How would you check to make sure it's working?No, the tongue test is not an option.

author: SeanB
author_rank: Super Contributor
timestamp: May 11, 2014, 05:46:23 pm
content: How about a photodiode to detect the light flashes? It just has to be able to see the flash, probably using a small glass welding shield to attenuate direct light and then it generates a pulse when the flash fires. A phottransistor and a simple comparator to give a pulse is trivial.If you want to detect the actual firing pulse a simple insulated wire near the tube and connected to the base of a transistor via a resistor of say 10k will give a pulse when it triggers.

author: DJ
author_rank: Unknown
timestamp: May 11, 2014, 08:44:06 pm
content: Capful of clorox on top of rubbish does wonders for pests. Not to mention liability for crisping the garbageman.Plan B: leave fast food atop and the bear will become tubby and unable to chase anyone without a motorized scooter. PETA may object.Plan C: an exceptionally large trebuchet.I like the last

author: GreyWoolfe
author_rank: Unknown
timestamp: May 11, 2014, 09:25:16 pm
content: And lots of honey in the basket of the trebuchet to hold the bear and a VERY long release so you can do it from the house.

author: superUnknown
author_rank: Regular Contributor
timestamp: May 12, 2014, 03:10:52 am
content: Sorry, clarification:I'm removing the strobe bulb and running the excitation lead and ground lead to terminals on the lid of the bin.
measuring THD with vintage AWA-F240 Distortion/noise meter.   - Page 1
Forum section: electronics / beginners

author: ErwinsCat
author_rank: Regular Contributor
timestamp: July 28, 2018, 10:58:49 am
content: HI, I'm trying to measure the THD with an old Distortion & Noise Meter AWA-F240http://www.smoke.com.au/~ic/audio/AWA-F240.htmlI am not sure how to read the analog meter! I'm assuming when the METER RANGE selector is in the "0dB/100%/1V" range, the number 10 in the second row in the display means 100% THD.also if it was in noise meter, a number 3 in the scale (3rd row) meant 1 volt of oRMS noise or +2dB because of the selector was "0dB/100%/1V" range?image1: the unit imageimage2: meter detailimage3: output voltage/signal (i'm assuming this is the filtered out harmonics waveform )image4: input voltageimage5: input/output signalthanks
Measuring the direct output of an ultrasonic amplifier at the transducer - Page 1
Forum section: electronics / beginners

author: JeepinBoone
author_rank: Newbie
timestamp: February 21, 2023, 03:43:49 am
content: Quick question. Not a newbie with a scope but AM ZERO experience measuring Ultrasonic. Working on a sweepSONIK 40khz ultrasonic sweep controller and do not want to blow inputs, probes, driver. I have 1x-10x probes and ain't even gonna... Found the P4060 probe on ePay cheap. @2KV X100, is that safe enough or do I need to go for a HV module? I really don't wanna blow an input module on a good scope. Prolly gonna test probe on cheapest scope before go to good scope.

author: BillyO
author_rank: Super Contributor
timestamp: February 21, 2023, 03:42:55 pm
content: Do you want to measure power or just get a look at the waveform?

author: JeepinBoone
author_rank: Newbie
timestamp: February 21, 2023, 11:17:38 pm
content: I just want to see the waveform. I bought the sweepSonik and transducer dirt cheap, pulled the lid and want to poke around inside without letting out the magic smoke on the scope. I can wrap a wire around the output and see a waveform but I am hoping for a probe for more direct poking.

author: BillyO
author_rank: Super Contributor
timestamp: February 21, 2023, 11:45:39 pm
content: The transducers in ultrasonic cleaners are high voltage. One I have here is 1500V so I would recommend being extremely careful. Multi-KV probes are available but are not cheap ($500++). Wrapping a wire around one of the drive leads might work, but if you don't hurt yourself, the cleaner or your scope in dong so the waveform you will see will be related to the current through the transducer, not the voltage.
Measuring Transformer Leakage Inductance - Page 1
Forum section: electronics / beginners

author: killingtime
author_rank: Regular Contributor
timestamp: January 11, 2024, 04:49:48 pm
content: Hi,I'm looking to measure the parameters below on a line frequency isolation (1:1) transformer. Schematic attached.1) The capacitance between pri & sec windings (C).2) The leakage inductance on both primary and secondary windings (LeakPri & LeakSec).I only have an LCR meter. No transformer specific tools.For 1) I use a capacitance meter between A and C, leaving all other connections open?I'll be using an LCR meter and lowest frequency it will go to is 100Hz, not 50Hz. Would this make a big difference? I think the core is silicon steel.For 2) I could short the secondary (C & D) and then measure the inductance across the primary (A & B) using an LCR meter. The short on the secondary will be transferred to the primary effectively shorting the primary out leaving only the leakage inductance. The issue is there's leakage inductance on the secondary as well, so this will be transferred over. As it's an isolation transformer (1:1 winding ratio) that means the inductance reading I'll get will be the sum of both the leakage inductance of the primary and secondary. It will not possible to isolate the pri & sec leakage inductance using this method.Can anyone see a problem with the above methods?Thanks.
Measuring voltage across ultrasonic transducer? - Page 1
Forum section: electronics / beginners

author: cds333
author_rank: Contributor
timestamp: December 29, 2021, 07:26:55 am
content: I am getting two significantly different readings when measuring the AC voltage across this transducer (PZ1 in the picture). The board is from a junkyultrasonic dog bark devicethat is powered by a 9V.My multimeters are telling me it is 36V (chinese TRMS meter) and 48V (Fluke 16), and the scope is telling me it is much higher (see attachment).Would someone be so kind as to explain this discrepancy?[ Specified attachment is not available ]

author: Chalcogenide
author_rank: Regular Contributor
timestamp: December 29, 2021, 08:28:58 am
content: The fluke 16 is an average responding type of multimeter, so you can expect a very marked difference compared to the true RMS meter, given that the waveform is not at all sinusoidal.The reason why the true RMS meter is off compared to the oscilloscope most likely lies in the fact that the multimeter probably has only few kHz bandwidth, so the meter does not capture "correctly" the fast risetime of the waveform, and under-estimates its amplitude, while the oscilloscope with its few MHz bandwidth has no issues with it.

author: cds333
author_rank: Contributor
timestamp: December 29, 2021, 09:18:10 am
content: The meter's specs are- up to 10MHz frequency, and 1kHz AC Bandwidth (had to dig a bit to find that). I assume that the latter is the relevant spec, given that the signal is over 1kHz.So if I generate a pure sine wave and then repeat the test with both meters and the scope, I should probably see a much closer reading?

author: Kleinstein
author_rank: Super Contributor
timestamp: December 29, 2021, 09:31:49 am
content: Quote from: cds333 on December 29, 2021, 09:18:10 amThe 10 MHz is the measurement range for measuring the frequency. This is not the bandwidth wor measuring AC voltage or AC current.With normal DMMs the BW for AC measurements is more like in the 5 kHz to 300 kHz range.The main part of the measured signal is relatively slow (2.4 kHz) from the scope - which is odd, but there are still some higher frequency parts.The scope reading is not that much higher: the RMS reading is 58 V.The True RMS and simple rectifier in the Fluke 16 also makes a difference.The transducer is likey used in a resonant mode and thus with a high impedance. The meters often have quite some input capacitance and can effect the actual measured signal. This should be visible when measureing with 1 meter and the scope at the same time. For the scope it can make a difference wether a x1 or x10 probe is used. Already the cables to the meter can have a visibe effect.

author: radiolistener
author_rank: Super Contributor
timestamp: December 29, 2021, 09:53:13 am
content: Quote from: cds333 on December 29, 2021, 09:18:10 amUltrasonic transducer for dogs work at about 24 kHz. Your DMM cannot capture it's Voltage properly, because it has max 1 kHz bandwidth limit.I think you can believe your oscilloscope which shows 58.27 Vrms.If I remember correctly, these Chinese transducers with 24 kHz resonant frequency have maximum rating about 60 V.
Measuring voltage drop on power rail - Page 1
Forum section: electronics / beginners

author: bhj99
author_rank: Contributor
timestamp: August 20, 2023, 03:21:47 pm
content: Hello,I would like to measure the voltage drops for the 3.3V_M.2 power rail on a eval board design and wanted to get some thought on the best approach. The 3.3V rail is an output from an LDO and that is being filtering using a ferrite bead to generate the 3.3V_M.2 rail used for a connector that hosts an M.2 SSD (see schematics attached). Would a fair approach be to use a differential probe to measure across both the pads of the ferrite bead E7, or would it be easier at the decoupling caps? Or would just using a multimeter be easier?

author: Manul
author_rank: Super Contributor
timestamp: August 20, 2023, 03:55:21 pm
content: Differential probe is not needed. Scope in general is not for accurate measurements. Use multimeter. I'm not sure what exactly you try to measure and what is your goal, but in this case I would measure voltage drop from LDO output up to the IC pins of interest. Don't forget that there will be some drop on the return path too (GND). Return path drop is usually less, because ground is typically distributed by massive copper planes and has less resistance. So total supply drop will be the sum of those.

author: bhj99
author_rank: Contributor
timestamp: August 20, 2023, 04:18:56 pm
content: Quote from: Manul on August 20, 2023, 03:55:21 pmAppreciate the feedback. Part of the intent to is validate DCIR drop power analysis.Sounds like I should put my red probe on one side of the ferrite (LDO output) and the black probe on the other (connector) side to make measurements easier. The IC at the connector is not easily accessible so it would be best to measure at larger components like the caps.

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 20, 2023, 05:04:50 pm
content: It will be millivolts at most. WIth a scope you'll only get noise. And you need a really good DMM to measure sub-mV.Normally you amplyfi it by 100, 200, whatever, so you get something much more usable.

author: Terry Bites
author_rank: Super Contributor
timestamp: August 21, 2023, 11:52:43 am
content: You could make handy widget with an instrumentation amp.A micropower like a $3 INA33 it has an input offset of 10uV, an error of 1% in 1mV.Set gain to 100 and chuck it in the draw. It will run for thousands of hours from a couple of AAs .A practical circuit is attached.

author: wasedadoc
author_rank: Super Contributor
timestamp: August 21, 2023, 12:02:18 pm
content: Quote from: Terry Bites on August 21, 2023, 11:52:43 amA practical circuit was not attached.(And the word is "drawer", not "draw".)

author: PartialDischarge
author_rank: Super Contributor
timestamp: August 21, 2023, 12:02:35 pm
content: To measure the steady drop use a multimeterTo measure switchings drop use a x1 probe with scope set at AC, easy to see mV changes

author: Terry Bites
author_rank: Super Contributor
timestamp: August 21, 2023, 09:24:08 pm
content: Errata the input resistors are 10k not 10meg. Ooops, drawers at half mast again.
Measuring Voltage from my frequency generator help. - Page 1
Forum section: electronics / beginners

author: Terry01
author_rank: Frequent Contributor
timestamp: March 13, 2018, 09:25:47 pm
content: How come when I take a measurement from my frequency generator I get funny measurement values on my DMM? If I set it to output a 5 VDC signal and hook it to any of my meters they all give me a different readings but none that equal what the FG says it's out putting. Like loads different! If I set it for any of the AC wave forms it's even worse! When I move the offset around the reading on my meter changes so I take it it's reading say the rising edge or whatever of the waveform but should my meter not compensate for that?Could someone help me understand this please? Thanks

author: hscade
author_rank: Contributor
timestamp: March 13, 2018, 09:31:34 pm
content: Can you tell us a bit more how your connection setup looks like?Keysight has proper app note:http://literature.cdn.keysight.com/litweb/pdf/5988-6916EN.pdf

author: Terry01
author_rank: Frequent Contributor
timestamp: March 13, 2018, 09:46:15 pm
content: Quote from: hscade on March 13, 2018, 09:31:34 pmIt's a cheap Feeltech 3224 FG and i connect it to my meter with a simple BNC connector out the FG with red and black croc clips on the other end of the cable. I connect the red and black croc clips to the red and black leads that are on my meter. Nothing fancy!Thanks for the help.

author: Terry01
author_rank: Frequent Contributor
timestamp: March 13, 2018, 09:53:37 pm
content: Quote from: hscade on March 13, 2018, 09:31:34 pmAh cool! As soon as I started reading the link I had a DOH!! moment!I understand now, I will read all the link and I am sure by the time I get to the end I will understand it. My oscilloscope has a "measurements" button that gives all the readings I need from a signal so I can compare my DMM's to these and see what part of the signal my different meters are reading.Thank you very much again!!

author: hscade
author_rank: Contributor
timestamp: March 13, 2018, 10:21:05 pm
content: Thank keysight, daniel & wave :p
Measuring voltage on through the hole soldered components on PCB - Page 1
Forum section: electronics / beginners

author: cepwin
author_rank: Unknown
timestamp: October 29, 2017, 10:18:40 pm
content: I'm trying to debug why I'm getting a white screen on the DSO-138. Test mode indicates an open and I'm trying to measure the voltages on the various points they specify. When I go to measure the voltages around resistors, etc. I get unstable values on my multimeter (and in some cases wildly off the specified values.) Any tips on using the multimeter to take these measurements? Any tips on finding opens?
measuring voltages up to 400 volts safely with scope - Page 1
Forum section: electronics / beginners

author: davy peleman
author_rank: Regular Contributor
timestamp: February 04, 2018, 03:51:29 pm
content: i have a portable scope: velleman hps50. the manual says it's cat.2 (up to 600v) but then a little later it says the maximum voltage is 100 Vp. now i'm confused. i need to measure ripple on the output of an isolation transformer that's in a tube signal generator. how can i do that??? wich probes and attentuator do i need??? i'm new and this is confusing me. i'm very concerned about safety. so can somebody please explain how to proceed.thanks

author: danadak
author_rank: Super Contributor
timestamp: February 04, 2018, 04:12:02 pm
content: The manual shows quite a lot lower Vinmax on page 71.https://www.vellemanusa.com/downloads/0/user/usermanual_hps50.pdfUsing 10X probe scales the voltage, but then you have to consult probe Vmax specs.Additionally you may want to do differential measurments in order to eliminate groundloop problems with scope.http://download.tek.com/document/51W_10640_1.pdfhttp://www.techni-tool.com/site/ARTICLE_LIBRARY/Tektronix%20-%20IsolatedInputOscopes.pdfhttp://web.mit.edu/6.101/www/reference/ABCprobes_s.pdfhttps://www.eevblog.com/forum/beginners/how-to-perform-differential-voltage-measurement-with-an-oscilloscope/Regards, Dana.

author: Simon
author_rank: Unknown
timestamp: February 04, 2018, 04:25:30 pm
content: Topic continues here:https://www.eevblog.com/forum/beginners/measuring-voltages-up-to-400-volts-safely/new/#new
Measuring with DC Load (plus remote sensing) - Page 1
Forum section: electronics / beginners

author: sstepane
author_rank: Regular Contributor
timestamp: December 26, 2017, 01:06:56 pm
content: Hi,I would like to ask a question if someone experienced could clarify.Assume two setups:1 - DC Load, 10 cm long 10 sq. mm. thick wires with remote sensing attached2 - DC Load, 100 cm long 5 sq. mm. thick wires with remote sensing attachedI'm pretty sure that voltage will read properly, but what about current? Say 30 Amps with every setup?Thanks in advance and sorry if it is a dumb question.

author: jeroen79
author_rank: Frequent Contributor
timestamp: December 26, 2017, 04:22:33 pm
content: The voltage would always read "properly", what matters iswhereyou want to read it.If you want to rule out the voltage drop over the powerwires then you attach the load's sensewires to the source.If you want to include the effect of the powerwires then you attach the load's sensewires to the load.The current would flow through the load so unless you attach something in parallel the current measured by the load would be the same as the current going through the source.See for yourself:http://lushprojects.com/circuitjs

author: sstepane
author_rank: Regular Contributor
timestamp: December 26, 2017, 09:41:04 pm
content: Thanks, I just wanted to make sure that no measuring corrections required for current, unlike voltage.

author: danadak
author_rank: Super Contributor
timestamp: December 26, 2017, 10:20:30 pm
content: Its fairly common to use a Rsense for current measuring to a load.Usually done with a low value Rsense, 1 ohm or less. Conditioned byan IA to reject CM voltages.You can sense high side or low side with this technique, each coupledwith design decisions.https://en.wikipedia.org/wiki/Current_sensing_techniqueshttp://cds.linear.com/docs/en/application-note/an105fa.pdfhttps://www.microsemi.com/document-portal/doc_view/14646-an-7-a-simple-current-sense-technique-eliminating-a-sense-resistorhttp://www.electronicdesign.com/test-measurement/choose-right-current-measurement-technique-your-applicationhttp://www.vishay.com/docs/30304/currentmeasurement.pdfRegards, Dana.
Mechanical Design Software choice - Page 1
Forum section: electronics / beginners

author: lilmantis
author_rank: Contributor
timestamp: September 22, 2017, 03:25:22 pm
content: Hello everyone, I want to design some mechanical parts for some projects and I was thinking about learning Fusion 360 which seems to be free of charge for hobbyists. Do you think this is a good choice and if not what else should I look into?

author: KuroZ
author_rank: Contributor
timestamp: September 22, 2017, 03:53:28 pm
content: Give it a go. If you like it, use it.I have tried lots of CAD software, both commercial and free, and I stick to OpenSCAD for everything mechanical. Never got really used to other modeling software, though I use FreeCAD sometimes.I'm yet to try SolidWorks, which seems to be good from what I've heard.

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: September 22, 2017, 03:58:19 pm
content: I'm a mechanical newbie, informal training from Lego. Even still, if I can think it, I can make it with Fusion 360.It's by far the best I've tried.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: September 22, 2017, 03:59:08 pm
content: Quote from: lilmantis on September 22, 2017, 03:25:22 pmFusion 360 is awesome. Make sure you checkout the various YouTube tutorials.

author: janoc
author_rank: Super Contributor
timestamp: September 22, 2017, 04:15:08 pm
content: Some other options:https://www.freecadweb.org/(completely free/open, desktop app, but not as full featured as Fusion360 or Onshape, but getting better)https://www.onshape.com/(totally web based, so can work even on the go, commercial but free for personal use. Comparable to Fusion360 with more logical UI and less slugishness, IMHO)http://www.openscad.org/(scripting, good for procedural generation of objects but requires a certain mindset and very good orientation in space so that you can write sensible code ...)https://www.rs-online.com/designspark/mechanical-software(Free, but haven't tried it. Integration with DesignSpark PCB tools is an advantage. Regular offline tool, no Internet connection needed)
Mechanical Electronic Circuit - Page 1
Forum section: electronics / beginners

author: metrologist
author_rank: Super Contributor
timestamp: June 07, 2023, 03:56:32 am
content: Interesting concept.

author: RJSV
author_rank: Super Contributor
timestamp: June 07, 2023, 05:19:59 am
content: Nice!Has interesting base configured in 6-sided 'cells', looks like with individual locks holding cells to each other, for varied and expandable support base system.Seems like at least two kit types available.

author: Benta
author_rank: Super Contributor
timestamp: June 07, 2023, 10:20:37 am
content: Already being discussed in the General section.

author: Jwillis
author_rank: Super Contributor
timestamp: June 08, 2023, 02:09:30 am
content: I want one.

author: barshatriplee
author_rank: Regular Contributor
timestamp: June 08, 2023, 08:27:09 pm
content: Has anybody here used this mechanical transistor in real life?

author: metrologist
author_rank: Super Contributor
timestamp: June 10, 2023, 09:23:30 am
content: Quote from: barshatriplee on June 08, 2023, 08:27:09 pmProbably just the mfg of the toy making revenue, teachers, and of course the youtube creator...

author: metrologist
author_rank: Super Contributor
timestamp: June 10, 2023, 09:24:36 am
content: Quote from: Benta on June 07, 2023, 10:20:37 amSo it is...https://www.eevblog.com/forum/chat/mechanical-electronic-circuit-boards-is-messing-with-my-mind/
Mechanical pulse counter utility meter input to LVTTL - Page 1
Forum section: electronics / beginners

author: ptr727
author_rank: Newbie
timestamp: January 19, 2024, 06:23:18 pm
content: Hi, I monitor gas and water usage at my home using dry contact / reed switch / open drain inputs from the utility meters, long wires, and then ESP32.Controller supply voltage is 24VDC, switching converter to 5V (or USB for programming), then LDO to 3.3V.One of the new meters I am testing is electronic with an open drain and max 12V, so I cannot use the 24V in pull-down mode, I will use 5V instead.I am redesigning my controller, and looking for design ideas on minimizing interference when running long wires, and converting from 5V to 3.3V LVTTL.My old design ran for years with a simple pulldown directly to the ESP32 input, but, it took some fiddling to do proper debounce in code, looking to improve the design.I am considering:1) Opto with LVTTL Schmitt trigger output, e.g. H11L3.2) RC low pass input to LVTTL Schmitt trigger, e.g. SN74LVC2G17.Both devices have "some" ESD protection, and the inputs are passive, so I am not planning on adding any additional reverse polarity/ESD protection, or should I?Any suggestions for known reliable designs to use for such pulse detection over long wires (not too dissimilar to an alarm system less the tamper detection)?Attaching an example schematic with two options.

author: Terry Bites
author_rank: Super Contributor
timestamp: January 22, 2024, 03:45:46 pm
content: Use current loop signalling on both lines. That gets you good noise immunity, small interfering potentials just get swallowed in the low value termination resistors.
Mecmesin Torque Gauge - Page 1
Forum section: electronics / beginners

author: Choco73
author_rank: Newbie
timestamp: April 26, 2020, 01:04:35 pm
content: Hey all I new to here but i have a issue at work where a worker got a small shock from a torque gauge mounted on a steel unearthed plate, I have done some investigating and found the 240V AC to 9V DC power adapter is discharging the 9V DC ok for gauge but i also measured 70V AC on the output plug to earth??? Is this something to do with Regulated and Un-Regulated DC supplies??
Med2000 Camera found - now what?? - Page 1
Forum section: electronics / beginners

author: Delphium
author_rank: Newbie
timestamp: December 01, 2023, 10:52:36 pm
content: Hi everyoneNewbie to this forum. Hope you're all well.I came across a med2000 camera (shown in the photos) about 2 years ago. It powers up but thats as far as I have got.I've contacted meditherm a number of times but they are very reluctant to give me a copy of the wintes2/3 software.The simple question is, how do I get access to the Wintes software and unlock code?I note in previous threads that it can be circumvented inside to operate as a stand alone camera (in a restricted fashion), but I'd prefer to see if I can use it in its default way first (if possible).Your help would be greatly appreciated.Best,Mark

author: Jwillis
author_rank: Super Contributor
timestamp: December 02, 2023, 12:29:52 am
content: You could try herehttps://www.eevblog.com/forum/thermal-imaging/compix-222-meditherm-med2000-iris-tes2/msg5168664/#msg5168664

author: jbradford941
author_rank: Newbie
timestamp: July 21, 2025, 03:38:12 pm
content: Hello!I am facing the same issue with this Med2000 camera.. I've called the company and they were NOT helpful to say the least.. Have you found an 'unlock code' that worked? or did you discover a work around?.. any information is greatly appreciated!

author: wootwoot
author_rank: Contributor
timestamp: July 21, 2025, 04:42:24 pm
content: Are they really manufacturing those in Noosa??Quote from: jbradford941 on July 21, 2025, 03:38:12 pmThey're probably busy smashing down cans of pineapple juice, or about to go out fishing. Or both.
Medium Volage Power Inductor - Page 1
Forum section: electronics / beginners

author: 1uk3
author_rank: Contributor
timestamp: January 31, 2018, 11:11:11 am
content: HelloI'm working on a boost converter with 48V input and 250V/1A output. My problem is that i can not find an inductor with a high enough voltage rating.The inductor should be between 33µH and 56µH, Isat/Imax > 6A. There are a lot of inductors like that but either are rated to ~80V or do not give a voltage rating at all.Do you know any specific series or manufacturers (available at any standard distributor if possible) for that?Another option would be three smaller 15µH inductors in series. Is there a problem with this solution?Many ThanksLukas

author: Zero999
author_rank: Super Contributor
timestamp: January 31, 2018, 11:24:40 am
content: 250V isn't that higher voltage. The inductor will only see VOUT-VINand the insulation on the enamelled wire should be enough to withstand 250V with no problems.Failing that, how about winding your own inductor?

author: 1uk3
author_rank: Contributor
timestamp: January 31, 2018, 01:25:58 pm
content: Thanks for your answers.Yes it is only 200V across the winding and i can not understand why they are rated so low.I think i will try something like thiskatalog.we-online.de/pbs/datasheet/7443634700.pdf. The voltage is spread over a few windings and i can't imagine an insulator that can' handle 50V.QuoteI need quite a few but for a one-off project. This would be really annoying to do.QuoteAgain no voltage rating although it would work. I contacted CoilCraft already and they dodged the question with some marketing ****.