hybridfree/eevblog-posts huggingface dataset:
Meaning of letter r as measurement unit in Agilent U1733C? - Page 1
Forum section: electronics / beginners

author: Per Hansson
author_rank: Unknown
timestamp: November 29, 2020, 05:42:58 pm
content: Hi, hoping someone can tell me what I have done wrong in this setup:I am measuring a 10000µF capacitor, and I have disconnected the wires to it so it is just the capacitor in being measured...The ZLCR meter was unable to auto-identify the capacitor so I selected capacitance mode manually, and 100Hz as this is filtering a bridge rectifier.The meter then shows a value of 9.384rnFI have no idea what the "r" stands for, and from this reading if we skip the "r" and just look at it as nF it would be very obviously bad.But my Fluke 28-II shows it as 9810µF and with it out of circuit I have 8VAC of ripple, with it in circuit the ripple is in the millivolts range, so the cap is ok.What is going on here, is it user error?

author: golden_labels
author_rank: Super Contributor
timestamp: November 29, 2020, 05:49:15 pm
content: Possibly that is meant to be ‘m’, not ‘rn’? An ‘m’ made from ‘n’ with additional leg. 9.384mF = 9384µF.

author: Benta
author_rank: Super Contributor
timestamp: November 29, 2020, 05:51:28 pm
content: It's showing mF, but the LCD layout has to accommodate both nF and mF at the same place, leading to this somewhat "creative" display.

author: Per Hansson
author_rank: Unknown
timestamp: November 29, 2020, 05:57:50 pm
content: Uhh, wow, glad I asked then!Damn meter could just show 9384µF then to not confuse me!But then we would not have this thread, hope it helps someone else!

author: golden_labels
author_rank: Super Contributor
timestamp: November 29, 2020, 09:37:01 pm
content: Your eyesight is too good! Agilent thought no one will notice that gap between segments.

author: Dave
author_rank: Super Contributor
timestamp: November 30, 2020, 01:31:53 am
content: Quote from: Per Hansson on November 29, 2020, 05:57:50 pmShame on Agilent to assume that the users of their products understand SI prefixes!

author: Per Hansson
author_rank: Unknown
timestamp: November 30, 2020, 05:15:42 pm
content: Quote from: golden_labels on November 29, 2020, 09:37:01 pmHaha thanks but I am not sure about that: I just got new glasses this Friday however the measurement was taken before that, and my old glasses where quite a bit offQuote from: Dave on November 30, 2020, 01:31:53 amAre you being a smartass or did you not even read the thread?!
Meaning of O-NEG marking on an electrolytic - Page 1
Forum section: electronics / beginners

author: phonedawgz
author_rank: Newbie
timestamp: February 22, 2020, 09:51:46 pm
content: Doe the O-NEG marking on this electrolytic indicate the lead on the bottom with the engraving is the cathode? If not what does it indicate?

author: Gyro
author_rank: Super Contributor
timestamp: February 22, 2020, 10:21:36 pm
content: Yes, it indicates the textured surface on the rivet on the bottom. It seems rather redundant in this case as the sleeve has the white negative band down the side too (Maybe they use it themselves to align the sleeve).

author: phonedawgz
author_rank: Newbie
timestamp: February 22, 2020, 10:51:22 pm
content: Thank you
Meaning of parallel dotted lines and sines in connection lines - Page 1
Forum section: electronics / beginners

author: Back2Volts
author_rank: Unknown
timestamp: August 12, 2016, 01:08:03 pm
content: What is the meaning of the dotted lines in the attached schematic ? All I can think is that they are connector related.What about the sines on the connector on the upper right corner ? There are two distinct sizes. AC of low/high voltage ?

author: NottheDan
author_rank: Frequent Contributor
timestamp: August 12, 2016, 01:15:21 pm
content: Maybe I am missing something or the pig viewer here doesn't show something but the only dotted lines I see indicate the separate PCBs.

author: Andy Watson
author_rank: Super Contributor
timestamp: August 12, 2016, 01:20:43 pm
content: Search the forum for a previous visit to this schematic - there is much that is wrong with it. The dotted lines vaguely define PCB modules and the arrows in the top corner hint at the connections between modules. However, if you try to follow the connections you will find they are inconsistent.Edit: See this thread:https://www.eevblog.com/forum/repair/mastech-hy5020e-50v-20a-bench-supply-economical-to-repair/

author: Back2Volts
author_rank: Unknown
timestamp: August 12, 2016, 01:53:48 pm
content: Quote from: NottheDan on August 12, 2016, 01:15:21 pmNever mind. My Adobe Reader was missing a font pack. The funny thing is that when I installed it, the affected areas do not have any off looking characters... but obviously pulled from a different code set.Problem solved.

author: Back2Volts
author_rank: Unknown
timestamp: August 12, 2016, 02:23:18 pm
content: Quote from: Andy Watson on August 12, 2016, 01:20:43 pmThank you for bringing this up. I will definitely read about it and open the PS to look for any odd stuff. I got it used six moths ago, but have not gottem to look at it yet. I am still trying to find the proper schematic for my Shenzhen Mastech HY3003-3, and somehow run into this one. I suspect many areas are similar to the one attached.
Meaning of reverse voltage in anti-parallel diode optocoupler - Page 1
Forum section: electronics / beginners

author: Back2Volts
author_rank: Unknown
timestamp: October 15, 2017, 08:29:00 pm
content: I am wondering to what does it refer to. The VOS628A is giving 6V in maximum ratingshttp://www.vishay.com/docs/83466/vos628a.pdf

author: Signal32
author_rank: Frequent Contributor
timestamp: October 15, 2017, 08:37:23 pm
content: It would appear it refers to just that ... the maximum reverse voltage for either of the two diodes.How i'm guessing it is relevant is probably if you blow out one of the diodes, you still can't apply more than 6v in reverse of the 2nd one or you'll damage that too.

author: Audioguru
author_rank: Super Contributor
timestamp: October 15, 2017, 08:45:31 pm
content: Does it have two LEDs connected with opposing polarities? Then a reverse voltage will occur only of one LED burns out.
MeanWell RS-150-xx : Schematics and V sense - Page 1
Forum section: electronics / beginners

author: PinheadBE
author_rank: Regular Contributor
timestamp: September 15, 2023, 10:43:03 pm
content: Hi,I'm looking for a schematics of the MeanWell RS-150-xx range of PSU. (NOTLRS-150-xx)I would like to add an external voltage sense to compensate the loss in wires, but need to know where to connect it inside the PSUThanks !
Measure 8 channel 4-20mA; isolated - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: July 05, 2015, 03:05:29 pm
content: 1. Need to measure 8 channel 4-20mA. Ckt is 3.3V powered.2. One option is to measure by adding a resistor of 165ohms (or 150ohm for error margin) & get 3.3V.But problem is I have to ground all the resistor connection to that of ADC.I want to keep all of them isolated.3. I have read abt receiver RCV420, but its minimum voltage requirement is higher.4. Is there any way to do it isolated.

author: commie
author_rank: Frequent Contributor
timestamp: July 05, 2015, 06:19:24 pm
content: Hi,I don't think there is an solution to your measurement problem as it is.Granted they all should be isolated but isolated at the instrument end or output. If you have a DCS then all the process instruments in the field must be isolated such that they maybe read in at the DCS input using a non isolated multichannel adc plugin card or pcb with a common ground.There is another alternative, DCS manufactures can supply isolated inputs to their input pcb plugin multi channel adc's but then they want big big bucks for them.Note also, if you have 8 instruments feeding a non isolated pcb adc plugin, 7 might be okay but one is causing ground loop problems then all 8 will not work.4..20mA ground loop comes about because electronic instrument designers use the full +-15V supply for headroom giving maximum resistance compliance, great but it causes ground loop problems and the poor teckie has to deploy a passive isolator which isn't ideal I might add.Ideally instruments should be designed with a single positive supply exclusively to avoid ground loop problems, ie., single 24V only.

author: PSR B1257
author_rank: Frequent Contributor
timestamp: July 05, 2015, 06:45:15 pm
content: http://sine.ni.com/nips/cds/view/p/lang/en/nid/209075should do itIt's only 4k$ - bargainSince you are notoriously not replyingthat's about all I have to say

author: krish2487
author_rank: Frequent Contributor
timestamp: July 05, 2015, 07:25:08 pm
content: To add to what others have already said,1. Grammar. Please typecomplete, succinct, unambiguous sentences.2.NO Messaging "shorthand". An otherwise helpful contributor might not be help if he/she feels you are not professional enough in asking and responding.3.Clarity Of Thoughtbefore posting. The most important of all. Please formulate, completely, what you would like postbeforeposting.Do not assume that others might have faced a similar situation. They might or might have not. Either way, even for them to help youthey need to understandwhat you done. Mention explicitly what, where, how, why of your predicament.4.Respond back. So that those who spent their time trying to help you, wont feel they have done it pointlessly.
Measure Conductivity - Page 1
Forum section: electronics / beginners

author: alnstn10
author_rank: Contributor
timestamp: July 12, 2022, 05:20:38 am
content: I have a conductivity kit from atlas scientific, but the ezo conductivity module is not there. I just connected the sensor probe to pin A0 on the Arduino Uno with the analogRead command in the source code. However, I'm still confused about the output of the sensor. What is the source code for converting sensor output to microsiemens/cm?

author: Faranight
author_rank: Unknown
timestamp: July 13, 2022, 11:12:05 am
content: I'm not particularly familiar with the kit you're using, but generally you're expected tocalibratesuch an instrument before use. You would use two standard solutions with known conductivity (generally they would be water solutions of potassium chloride of known concentration) and then measure them individually. The values you have obtained via the ADC can then be used to calculate the conductivity of any future measurements via a linear equation.Keep in mind that conductivity is temperature dependent and will also change, should you change the probe that you are measuring with (cell constant).EDIT: Also, you shouldn't try to measure conductivity directly on the probe with an ADC. Conductivity meters apply an AC voltage to the probe that is typically 2 to 4 kHz square wave. This is to prevent electrolysis from taking place on the probe and to mitigate some other effects (ion migration, surface ion depletion, etc).
Measure current to detect when an comparator is oscillating? - Page 1
Forum section: electronics / beginners

author: e100
author_rank: Frequent Contributor
timestamp: October 13, 2024, 04:53:06 pm
content: A bit of an odd question, is measuring the current draw a reliable indicator of when a comparator has started to oscillate?My goal is to detect oscillation without the need for an oscilloscope or high speed circuit that has the bandwidth to detect a oscillating signal that could be at some unknown frequency in the MHz range.For example if it oscillated for 4 microseconds would I see a 4 microsecond long bump in the current draw or would it be more complicated than that?

author: TimFox
author_rank: Super Contributor
timestamp: October 13, 2024, 05:36:13 pm
content: When faced with amplifier circuits capable of oscillating at frequencies too high for my test equipment to see directly, I sometimes had to rely on DC shifts, especially if I could stop the oscillation by temporarily adding a capacitor somewhere to the circuit.I had a set of capacitors from ATC mounted on the ends of plastic rods to touch circuits for such tests.One amplifier on a test jig with N connector input, designed for 50 MHz, would take off at maybe 3 GHz, due to a GaAs FET. I could sense that with a commercial microwave detector diode module with an N connector, measuring DC at the “video” output BNC.
Measure differential output with different ground - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: September 28, 2016, 04:09:39 pm
content: 1. I have a application for measuring load cell differential output. Load cell is powered from 10V from a differnet supply while ADS1230 is powered from 3.3V which is different ground.2. On measuring output of load cell using multimeter, it comes out to be +-36mV.3. I have attached a circuit using ADS1230. Obviously it will not work since differential output have no common ground with ADS1230.What if I short negative differential output of load cell with ground of ADS1230. Can I do that.Again voltage will not be CMR range of ADS1230 which is AVSS+1.5V to AVDD-1.5VSo I am planning to use ADS1248 for this purpose & will use +-supply for it. In this ADS1248 can be used.4. One thing I want to know, can I somehow use ADS1230 in this application. provided cannot short two different grounds.5.Other thing is how multimeter operation works. In this black probe is not shorted with baterry ground? Then how does it measure the signal when there is no common ground?On other hand while measuring with CRO, we essentially short earth with one of signal reference.

author: Assafl
author_rank: Frequent Contributor
timestamp: September 28, 2016, 06:10:45 pm
content: A differential measurement doesn't really need a ground (except for noise shielding). The voltage is referenced between the positive and negative input. Voltage that is on both lines (common mode) is cancelled out by the amplifier.You have to make sure you don't exceed the voltage input of the amplifier (or use a resistor divider).You have to ensure one of the sides is floating. Otherwise ground becomes connected via mains or somewhere else. DMMs and other meters are floating, Hence you can connect them to any grounded or ungrounded voltage (within the safety rating).

author: Zero999
author_rank: Super Contributor
timestamp: September 28, 2016, 10:28:56 pm
content: The problem is, without the 0V line of the differential amplifier connected to the load cell circuit, the common mode of the amplifier will probably be exceeded. If it's impractical to run another wire to connect the 0V of the amplifier to the load cell, then connect two 1M resistors in series across the + & - outputs of the load cell and connect the middle of the 1M resistors to the amplifier's 0V rail.
Measure ESR with oscilloscope - Page 1
Forum section: electronics / beginners

author: Adrian_Arg.
author_rank: Frequent Contributor
timestamp: June 04, 2020, 03:28:59 pm
content: Hello friends, I am trying to measure the ESR of the capacitors, using a generator FY6900 and Rigol DS1054z, and the method that it uses is the one of the video that is in the link, that and similar bulls, I cannot reach approximate measurements taking as a witness an ESR meter.in spanishHola amigos, estoy tratando de medir el ESR de los capacitores, usando un generador FY6900 y Rigol DS1054z, y el metodo que usa es el del video que esta en el link, ese y toros parecidos, no puedo llegar a mediciones aproximadas tomando como testigo un medidor de ESR.

author: Vovk_Z
author_rank: Super Contributor
timestamp: June 04, 2020, 03:58:03 pm
content: The result always depends on measuring method. That's normal. The problem is only if a difference is very large - more than 50-100%, for example.

author: rstofer
author_rank: Super Contributor
timestamp: June 04, 2020, 04:23:25 pm
content: I think you are going to have to provide a lot more detail. It's pretty clear that w2aew's method will work but there are a couple of issues: Is the square wave coming from the FG between 0V and 1V? The waveform can not reverse below 0V (a symmetric waveform from -0.5 .. 0.5 will not work). What size capacitor? The FG frequency depends on the capacitance since the calculated Xc wants to be very close to 0 Ohms. For a 220 ufd capacitor, the author uses 200 kHz and Xc should be 3.6 milliohms.
Measure >30VDC with Microcontroller - Page 1
Forum section: electronics / beginners

author: metrologist
author_rank: Super Contributor
timestamp: March 05, 2018, 05:53:48 pm
content: I want to use my Arduino to log my solar panel output voltage and current. To measure the panel voltage, I though of using a simple resistive divider, but I am not sure if my panel can peak above voltages that I've seen (~34VDC max). I guess I could set up the network to split 50V to 5V and 45V, but that decreases my resolution. That probably doesn't matter enough for this application though. I was thinking of a 4.7k/47k divider (or a 50k, 25 turn pot).Any problems with that idea or a better solution?The current will be measured using a hall effect type of current sensor, or I will build a current shunt and use an op amp.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 05, 2018, 06:22:50 pm
content: no problem with that. if you care about overvoltage you may try clamp diode from the divider to 5V rail. but sim it first because i sensed nonlinearity if using zener from gnd to the divider, but clamp diode maybe ok. losing resolution doesnt matter i would say 34V to 2.5V divider then you have room up to 68V overvoltage, unless you need precision greater than 66mV.

author: MasterT
author_rank: Frequent Contributor
timestamp: March 05, 2018, 07:32:47 pm
content: AtMega has build-in current clamp diodes on all input, except reset pin, so you don't need an external one. As long as current is limited to < 1 mA you are safe, that would imply 34 V / 1mA = 34 kOHm minimum resistance in upper leg of the divider. To get better accuracy, you may put 0.1 uF capacitor between analog input and ground - in parallel to low side of the divider.

author: metrologist
author_rank: Super Contributor
timestamp: March 05, 2018, 07:47:12 pm
content: Really? I was just going to ask how to apply a clamping diode. I guess the current limit would be OK with a 47k leg.I was considering the solar charge controller may be introducing voltage spikes on its input. I have not checked that yet.
Measure in and output of a Mosfet - Page 1
Forum section: electronics / beginners

author: Apfelsaftbaum
author_rank: Newbie
timestamp: May 12, 2016, 09:36:07 pm
content: Hi there,first of all, i am a beginner when it comes to oscilloscopes, so please don`t be too hard with meI am working on a little PWM based led dimmer, using a n-channel mosfet (IRLB8721) to dim some 12V led strips. It seams to work as it should.Now i want to measure and compare the 3.3V logic signal with the 12V Output signal, to see if the mosfet switches all the way and to check the timing...Now my question: How can i measure the in and output at the same time with only one 2 channel oscilloscope (Siglent SDS1102)? Is that even possible?As far as i understand, i need a reference for the scope, but for the logic signal it would be ground and for the Mosfet +12V right?But the clips from both channels of the scope are directly connected...Anyway, i hope someone can help me out, thanks in advance!Greetings from Germany

author: uncle_bob
author_rank: Unknown
timestamp: May 12, 2016, 10:30:41 pm
content: HiSimple approach:Both scope probe clips go to ground. That's the reference for both signals.Trigger on the 3.3V logic input.The 12V signal will be swinging from +12 down to "something". It might be zero it might be another level. Since you are referenced to ground, you can directly read out what that voltage is. Since you are triggering on the logic input, any delay will show up as a shift of the 12V signal on the scope display.Hopefully that makes sense !!!Bob

author: alsetalokin4017
author_rank: Super Contributor
timestamp: May 12, 2016, 11:35:27 pm
content: In other words: Both probe references to Mosfet Source pin, which is normally tied to the circuit's ground or negative power rail. One probe to Mosfet Gate pin, and trigger on this channel. Other probe to mosfet Drain pin.While this mosfet has a very low Gate threshold voltage it might be happier with at least 4.5 volts to the Gate rather than the 3.3 volts.If the mosfet is turning all the way on, the Drain-Source voltage will be essentially zero.

author: Apfelsaftbaum
author_rank: Newbie
timestamp: May 13, 2016, 10:13:21 pm
content: A big thanks to both of you for your help!The method with the logic level being the trigger input worked out perfectly.I also put in a level shifter to 5V, with that the output signal now looks much cleaner than with 3.3VThanks for the hint there.
Measure low current with mV range? - Page 1
Forum section: electronics / beginners

author: ElectricPower
author_rank: Frequent Contributor
timestamp: January 06, 2023, 05:18:52 am
content: The answer is possibly very simple, but i want to buy an Currentranger for measuring deep sleep current of arduino etc.All videos i have seen show that everybody uses the multimeter in mV range for measure current. For a beginner like me thats strange. I have always used uA and mA mode.Why can't i use my multimeter in current mode for measuring current with Currentranger?And how can i be shure the Arduino pulls uA or mA when i measure with mV mode?Thats strange to me...

author: IanB
author_rank: Super Contributor
timestamp: January 06, 2023, 05:31:16 am
content: Quote from: ElectricPower on January 06, 2023, 05:18:52 amDo you have a reference for such a video? Can you post a link?To measure current you wish the meter to have the lowest resistance possible. A voltmeter theoretically has a very high resistance. So if you try use a voltmeter to measure current by passing the current through the meter, it would upset the measurement. You could use a voltmeter to measure the voltage drop across a resistor perhaps. You need to provide a reference before we can understand your question.

author: ElectricPower
author_rank: Frequent Contributor
timestamp: January 06, 2023, 05:36:19 am
content: Quote from: IanB on January 06, 2023, 05:31:16 amLook from 07:10 in this video. The multimeter is in mV range:

author: bdunham7
author_rank: Super Contributor
timestamp: January 06, 2023, 05:48:09 am
content: Quote from: ElectricPower on January 06, 2023, 05:18:52 amBecause the output of the Current Ranger is in mV. That's what it does--allows current through it and then outputs a voltage proportional to the current. It says right on the front--"mV per nA/µA/mA". Your multimeter actually does the same thing internally when you use it to measure current. There's a shunt, the current flowing through the shunt results in a voltage drop, the meter measures that voltage and then calculates and displays the current. The only meters that truly measure in current are analog movement meters from eons ago.

author: ElectricPower
author_rank: Frequent Contributor
timestamp: January 06, 2023, 05:55:16 am
content: Quote from: bdunham7 on January 06, 2023, 05:48:09 amAhh... then i understand. Thank you very mutch

author: WattsThat
author_rank: Frequent Contributor
timestamp: January 06, 2023, 06:09:08 am
content: The current ranger is an auto-ranging adaptation of Dave’s uCurrent (which is about half the price - when available).For a good explanation why the devices exist, check out YouTube for “ammeter burden voltage” or Dave’s “building a better ammeter” video series.

author: ElectricPower
author_rank: Frequent Contributor
timestamp: January 06, 2023, 09:46:44 am
content: Quote from: WattsThat on January 06, 2023, 06:09:08 amThanks. I will do that
Measure lumen output from flashlight. - Page 1
Forum section: electronics / beginners

author: mwestern
author_rank: Newbie
timestamp: August 28, 2020, 08:45:31 pm
content: How exactly would one go about measuring the lumen output from an LED flashlight? I have done a quick google search and found there are pieces of test equipment which can measure LUX. Not to be an idiot but is there a simple way, or simple piece of equipment which can measure lumens? Yes I realize what the difference between lux and lumens is.

author: RenThraysk
author_rank: Regular Contributor
timestamp: August 29, 2020, 12:11:49 am
content: For some crude measurements, there is the Ceilingbounce Android apphttps://github.com/zakwilson/ceilingbounceRequires an integrating sphere of some sort.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 29, 2020, 04:03:55 am
content: That CeilingBounce seems to be a very crude setup of the way to go.Some hints for further reading:https://html.duckduckgo.com/html?q=integrating+sphere+lux+measuementhttps://en.wikipedia.org/wiki/Integrating_sphere
Measure more than 200a with ACS758 - Page 1
Forum section: electronics / beginners

author: Yaroooo
author_rank: Regular Contributor
timestamp: August 11, 2021, 04:06:51 pm
content: Can I measure more than 200A with ACS758?Here's a double module:https://www.aliexpress.com/item/32862321547.html?spm=a2g0o.productlist.0.0.533f4161T3cdXE&algo_pvid=89f0b4fb-0d97-43a0-8015-0b1dd155d876&algo_exp_id=89f0b4fb-0d97-43a0-8015-0b1dd155d876-20&pdp_ext_f=%7B%22sku_id%22%3A%2265361047982%22%7DEach is 200A load. My rated current is 150A with possible 300A short peak. I'd like to measure also this peaks. Is possible to connect this two sensors in parallel (two separate wire from source to load) and then sum the read current from both?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 11, 2021, 04:27:44 pm
content: You can use a current divider. Connect the load through two shunt resistors in parallel. The current divides between them according to their resistances: I1 / I2 = R2 / R1 (where I1 is the current through R1, etc.). Or out of the total, I1 = I * R2 / (R1 + R2). Wire the sensor in series with one of the resistors. (Note that sensor and wiring resistance must be summed with the resistor to get the true result.)The tricky part is, wiring and contact resistances will all affect the result, at least unless you use relatively large shunt resistors (~mΩ?). Note also that wire has a strong tempco, so the balance will also drift as temperature changes. The tradeoff is how much power you can afford to dissipate in the resistors, versus how good of a match you need.Tim

author: fcb
author_rank: Super Contributor
timestamp: August 11, 2021, 05:22:57 pm
content: In theory, you could put two in parallel (back-back) and then rescale one of the outputs to give 0-400A.You would essentially be using one of the two as a pure shunt, you could possibly (invert one of them) and sum them to get a little lower noise/range - perhaps. Probably do this in your sampling system.There are thermal considerations possibly if you have them back-back at continuous high currents, also the leadframe is copper so the TC (temperature coefficient) is poor. Not the way to go if you need great accuracy and linearity.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 11, 2021, 07:53:59 pm
content: Using 2 sensors in parallel does would, if the resistance is suitable to divide the current about equally between the 2 sensors. Separate cables can do the job, but make sure that worst case 1 cable could still stand the full current, just in case.One should still measure both sensors and only than add he result. The exact ratio may change with temperature.

author: Yaroooo
author_rank: Regular Contributor
timestamp: August 12, 2021, 09:50:16 am
content: Quote from: T3sl4co1l on August 11, 2021, 04:27:44 pmI'd like to avoid use of shunts since on this currents they are very big. I've found the smallest one of 120mm x 35mm of 200++g (from aliexpress).Thank for answers, I'll try to use them in parallel.
Measure / Observe of noise on DC voltage using oscilloscope - Page 1
Forum section: electronics / beginners

author: xchg.ca
author_rank: Contributor
timestamp: August 11, 2021, 08:22:21 pm
content: I have Hantek dso5102p and want to check noise part of DC voltage.But I have problem - to see noise part I have to switch to mV ranges in same time DC voltage has to be in V range, and vertical position cannot really help ( still off screen )It seems like the scope does not have ability to specify DC offset to compensate, for example -12V ? Unless I do not know what I'm looking for. May be people familiar with Hantek dso5102p can help me.Also the same problem on analog Tektronix 2252May be there is a technique of some kind I can employ?Thank you

author: bdunham7
author_rank: Super Contributor
timestamp: August 11, 2021, 08:26:50 pm
content: In your channel menu do you have an option for AC coupling? Typically the options are DC, GND and AC. AC will switch in a blocking capacitor to keep out the DC. Do not do this with high voltage DC greater than the rated input of the scope (not the probes). Your Tek 2252 definitely has this feature, the buttons are right above the CH1 and CH2 inputs.
Measure Points for the Oscilloscope in different circuits. - Page 1
Forum section: electronics / beginners

author: Forser
author_rank: Contributor
timestamp: November 28, 2016, 07:01:46 pm
content: Greetings Everyone,I am curious on how you decide on what points you connect your oscilloscope probes at for say measuring a transistor in a circuit likeSince a Transistor has three legs and if i understand it right, it collects the current / voltage up to a certain point and when it hits it, it will release it out through one of the other legs.If i want to measure that the collecting and the release with two different probes, do i use the ground on both probes or just one of them and then hook one probe up to collector and the other to the base or emitter?I haven't been using my oscilloscope that much yet since i have been a bit worried about damaging it in some way.Thanks for the help!

author: tautech
author_rank: Super Contributor
timestamp: November 28, 2016, 07:16:19 pm
content: This is your guide:https://www.eevblog.com/2012/05/18/eevblog-279-how-not-to-blow-up-your-oscilloscope/

author: rstofer
author_rank: Super Contributor
timestamp: November 28, 2016, 07:57:00 pm
content: The emitters are solid at the + rail so they aren't interesting unless you worry about supply glitches.The collectors are the outputs and the bases are the inputs. This is an ideal application for a 4 channel scope.Scope ground leads to circuit ground.
Measure potentiometer value using a constante current source - Page 1
Forum section: electronics / beginners

author: metRo_
author_rank: Regular Contributor
timestamp: April 23, 2013, 11:41:09 am
content: Hi,I need to measure a potentiometer valuefrom a joystick. The usual way to do this is to use it as a voltage divider.But I remember from university that I use a constant current source to measure the potentiometer value but I couldn't remember the advantages of that application beyond this way if the power source varies I still get the same value.Could you explain me if that application will give me best results? per example about noise?PS: I'm thinking to use alm334Thanks

author: AlphZeta
author_rank: Regular Contributor
timestamp: April 23, 2013, 03:29:01 pm
content: QuoteHmm... the only thing I could think of is if you are measuring a resistance that changes so that by using a constant current (instead of constant voltage) you can avoid burning up the resistor should the resistance value be too small.Other than that, the simplest way is to just have the potentiometer tied to ground and a regulated Vcc and measure the wiper voltage via ADC.

author: kxenos
author_rank: Frequent Contributor
timestamp: April 23, 2013, 04:36:53 pm
content: If you want to read the ohmic value of an unknown resistor, it's easier if you have a constant current. The equation is R=V/I. If your I is constant then you only need to measure voltage to get the resistance. If you have a constant voltage then you measure the current. If you don't have neither constant voltage nor current you measure both.
Measure powerfactor LEDbulb - Page 1
Forum section: electronics / beginners

author: jdoppenberg
author_rank: Newbie
timestamp: October 24, 2012, 01:04:49 pm
content: Hi All,First of all, i do know nothing about currenct and so on... I'm a total noob!I'm working for a company that sells all kinds of lightbulbs.Now my boss wants to measure the powerfactor (non used current?)...What device do i need and how do i measure it.We already have a multimeter (Meterman 37XR)Price doesnt matter that much, only the result... it should be accurateSomeone who can help me with this?Gr, Jeroen

author: Psi
author_rank: Super Contributor
timestamp: October 24, 2012, 01:30:22 pm
content: It's not an area i know a lot about, however something like this would be pretty good i imaginehttp://www.fluke.com/Fluke/usen/Power-Quality-Tools/Troubleshooting-Power-Meters/Fluke-43B.htm?PID=56080Looks to be around $3,200 USD and you'd probably want a few of the accessories for probing thingsI'm sure there are cheaper tools if that's a bit expensive. That one looks to do a lot more than just power factor measurements.

author: mariush
author_rank: Super Contributor
timestamp: October 24, 2012, 02:36:37 pm
content: Some Kill-A-Watt type devices measure the power factor.Put several light bulbs in series to use more current than the minimum these meters can measure (these are fairly accurate from about 3 watts and up) and you can then get a value close to the reality, give or take a few percents.For example:https://www.amazon.com/dp/B000RGF29Q/ref=as_li_ss_til?tag=helpediacom-20&camp=0&creative=0&linkCode=as4&creativeASIN=B000RGF29Q&adid=19G46VTD81SRA61RJM42&

author: jahonen
author_rank: Super Contributor
timestamp: October 24, 2012, 02:49:59 pm
content: If you want something serious and still cheaper than Fluke 43 power quality analyzer, take a look at Gossen Metrawatt metrahit energy, a general purpose electronics DMM with single phase power measurement function.Regards,Janne

author: Zero999
author_rank: Super Contributor
timestamp: October 25, 2012, 08:31:08 am
content: Quote from: mariush on October 24, 2012, 02:36:37 pmCorrected.

author: jdoppenberg
author_rank: Newbie
timestamp: October 26, 2012, 06:17:49 am
content: We've chosen to go with the Zes Zimmer LMG95e

author: Unknown
author_rank: Unknown
timestamp: October 28, 2012, 07:57:34 pm
content: you can also choose an analog lab power factor meter: something like this:http://www.provincia.lucca.it/istruzione/collezioni_didattiche_scuola_collezione.php?id=95shouldn't be expansive as a power analyzer...
Measure strain using quarter bridge - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: January 30, 2015, 11:54:49 am
content: I have to measure strain & circuit is attached. I am using ADS1246 to measure strain, its a 24 bit adc from TI.For 1K SG1. SG nominal = 1000 ohms , with min = 900 ohms during compression & max = 1100 ohms during tension.2. I have used R5 to generate Vref for ADS1246. R5 produce Vref = 0.6V.3. Minimum resolution I need is = 0.5uV.Max voltage = +25.641mVMin voltage = -24.39mV4. I have used PGA = 64.For 350 ohm SG1. SG nominal = 350 ohms , with min = 315 ohms during compression & max = 385 ohms during tension.2. I have used R8 to generate Vref for ADS1246. R5 produce Vref = 0.6V.3. Minimum resolution I need is = 0.13125uV.Max voltage = +13.462mVMin voltage = -12.805mV4. I have used PGA = 128.My questions are:1. What will be resolution is? Is it:resolution = Vref / (2^23 * PGA)= 0.6 / (128 * 8388608) = 0.55nV.2. In datasheet I have read that noise is in uV with Verf = 2.5V.But in my case vref is also small 0.6V.3. Will be circuit be able to measure such low voltages4. I am using 3 wire quarter brigde.It involves error from 1 lead resistance.How can I remove error this error?(Only option I have to use quarter bridge. I cannot use half brigde, full or dummy gage in quarter bridge. My application is such.)Edit: 5. Any other better circuit in someone's mind. This application is battery operated so have to be low power circuit.
Measure upto +-40V using MCU - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: May 08, 2015, 12:14:48 pm
content: 1. I have to make a multimeter (very low cost basic) , measuring 0V-40V & in reverse also.2. I have a ckt which is attached.3. MCU is powered by +5V , 10 bit adc.4. First I have level shifted the signal to +2.5V i.e mid supply. Then 40V is divided into 2V.So that max signal can swing 0.5 to 4.5V at adc input of MCU.5. Any comments/suggestions on it?6. In simulation it works fine.7. Also I have added two back to back diode for protection in case of overvoltage.
Measurement aborted HP 54503A - Page 1
Forum section: electronics / beginners

author: xaaander
author_rank: Newbie
timestamp: January 31, 2023, 04:45:56 pm
content: Hello. I recently changed NVRAM.When I want to use ''blue functions'', selecting Frequency for example, I choise canal 1 with bnc from AC rear signal, I got this message:Function is off.Measurement aborted.It's the same with all function.How to turn on function ?Thanks you.

author: Stray Electron
author_rank: Super Contributor
timestamp: January 31, 2023, 09:26:09 pm
content: I have a HP 54510A and a couple of newer 545** models and AFIK there is no way to turn off those functions. I think that your message is due to some kind of malfunction and the software detecting that and is causing the measurement to abort.

author: xaaander
author_rank: Newbie
timestamp: February 01, 2023, 09:49:58 am
content: Ok. Thanks you. I 'll try to calibrage again

author: Stray Electron
author_rank: Super Contributor
timestamp: February 01, 2023, 05:52:25 pm
content: Have you checked that the rear output is actually putting out a signal?

author: xaaander
author_rank: Newbie
timestamp: February 02, 2023, 09:56:28 pm
content: AC rear signal is ok, but as you mean, DC signal isn't. Do you know what IC is using to create DC signal?Small connector from BNC to board is ok.

author: Stray Electron
author_rank: Super Contributor
timestamp: February 03, 2023, 01:17:39 am
content: No, I've never been inside of any of the HP 54xxx scopes so I have no idea. You might search through some of the old HP Journal articles and see if they have any articles about the 54xxx scopes. Those usually have a good technical description. The only "repair manual" that I've even seen for the 54xxx scopes just say to replace the entire circuit board and there is no technical information.
Measurement Categories (CAT I, CAT II, etc...) - Page 1
Forum section: electronics / beginners

author: Jwillis
author_rank: Super Contributor
timestamp: December 08, 2018, 12:25:34 am
content: Not be an alarmist but not all DMMs are not created equally and should be used in accordance to the Categories they are designed for.This is important for the novice to understand to prevent either damage to your DMM your potential fatal injury to yourself or some one else.Always read the Manufacturers Operators Manual.There has been a few topics on DMM on this forum and I thought it would be a good idea for people that are looking for a DMM to understand what the Measurement Categories (CAT I, CAT II, etc...) mean and the applications they are rated for.Transients are often referred to as voltage spikes or surges.This can happen on both AC and DCUnderstanding Measurement CategoriesAs you see each Category has several voltage ratings.Most CAT IV DMMs are rated 600V with transients not exceeding 8000V .So just because your DMM says CAT IV does not mean it will be rated for the highest transients.Understanding applicationDMMs with no rating are CAT I and should never be connected to CAT II,CAT III or CAT IV CircuitsI hope this clarifies and helps when selecting a DMM.If anyone has anything to add that would be a great help.

author: Vtile
author_rank: Super Contributor
timestamp: December 09, 2018, 10:34:16 pm
content: Generally yes. Even more important is to learn to predict the hazards and learn the instrument.That picture is a bit misleading and mainly apply only small houses, not ie. industrial environments. Energy storage devices are another can of worms. The latter is what beginner might encounter. Not so much the industrial networks.
measurement equipment guard - Page 1
Forum section: electronics / beginners

author: wieserfalke
author_rank: Newbie
timestamp: July 31, 2021, 08:00:26 pm
content: Hello,I recently came over the topic of measurement equipment guards an didn’t found very much Information about it.What I already think that I know:• It is there to prevent leakage currents for devices connected to mains.• To implement an guard the transformer needs a shield between the primary and secondary windingsWhat I hope someone can explain to me:1) What this guard is about?2) When I need an guarded measurement?3) How to measure something guarded?4) How to implement an Guard in an DIY measurement equipment?5) In winch type of measurement equipment do I need to implement an guard?Thanks for your Answer.GreetingsTobias Falk

author: TimFox
author_rank: Super Contributor
timestamp: July 31, 2021, 08:17:07 pm
content: Take a guarded ammeter, for example: the guard terminal is forced (by the meter) to the same potential as the measuring contacts. Therefore, if you don't want the current from another part of the circuit to contribute to the measured current, you connect that node to the guard. It isnotthe same as "ground".As another example, the DE-5000 LCR meter (among others) connects the device under test to two or four (non-grounded) terminals. Again, the guard terminal allows you to remove the impedance to another node from the measurement. For example, if you have a delta connection of three capacitors, connect the guard to one corner of the triangle and you will only read the capacitance between the other two, ignoring the series combination of the other two capacitors in the delta.

author: jeffjmr
author_rank: Regular Contributor
timestamp: August 01, 2021, 03:29:42 am
content: Ack!You had me following until the delta capacitor example.Seems to me you could only test the one cap opposite the guard. Or is one of the test leads co-located with the guard? In which case which two caps are under test?Apologies if this is a hijack.Jeff

author: coppercone2
author_rank: Super Contributor
timestamp: August 01, 2021, 06:29:35 am
content: the guard is forced to x voltage so you put node A at x volts, I assume this is a AC guard, which matches phase?not sure how a guard works for a AC signal like a LCR meter, with phase and all, I just know for DCyou basically connect a gain of 1 amplifier to the signal pin to drive the guard with a buffered version of what its guarding. the voltage is forced at low impedance. if there is 3 capacitors, one node (the one that is being measured) will cause the guarded node to mimic that voltage.

author: TimFox
author_rank: Super Contributor
timestamp: August 01, 2021, 01:49:32 pm
content: Quote from: jeffjmr on August 01, 2021, 03:29:42 amIn the Delta case with three capacitors: If you connect the guard to terminal 3, then you measure the capacitance from 1 to 2. If you move the guard to terminal 2, you measure from 1 to 3. etc.
Measurement mic & preamp sensitivity - Page 1
Forum section: electronics / beginners

author: mitchy_g
author_rank: Newbie
timestamp: September 11, 2014, 07:06:56 am
content: Hi EEVblog folks,Beginner here and I'm putting a stop to my lurking!I have a measurement mic and preamp combo with an"open circuit sensitivity"of 50mV/Pa.Today I put together the constant current supply (4mA) and starting measuring the sound waves with my scope.Constant current source schematic here (http://sound.westhost.com/project134.htm). Using the JFET variant.Everything looks fine I can see the mic is getting bang on 4mA, when I speak into the mic I can see my voice etc.Now onto measuring!With my sound level calibrator set to94dB (1Pa)I was seeing5.0mV(RMS)With my sound level calibrator set to114dB (10Pa)I was seeing44.8mV(RMS)The results are coming back pretty much 10 times lower than the spec for "open circuit sensitivity".Am I right to think that the voltages are much lower due to the mic/preamp driving the scope input (1meg ohm) instead of a open circuit?Wouldn't it be better if they quoted voltages at a know circuit impedance?Is it inevitable that I'm going to have to build more amplifying circuitry? (I though the sensitivity of this mic was reasonably high and I'd be able to sneak it straight into an ADC)Let me know if you need anymore mic specs or info.Thanksmitchy_g

author: w2aew
author_rank: Super Contributor
timestamp: September 11, 2014, 04:35:23 pm
content: Is your scope vertical scale set to expect a 10x probe attached?

author: mitchy_g
author_rank: Newbie
timestamp: September 12, 2014, 02:10:11 am
content: I'm at work so I cant check for sure, but just with some quick research I found;Standard Rigol DS2072 comes with RP3300 probes. It is detailed as a 10:1 (http://www.rigol.com/prodserv/Digital%20Oscilloscopes/attachment/)The last memory I have of the probe settings was that it was set to "1x"......Looks like this could just be a trap for young players. I'll be back to report in detail!Mitch

author: mitchy_g
author_rank: Newbie
timestamp: September 12, 2014, 09:37:40 am
content: Yup, I changed it to 10x and the voltage readings were correct.I first checked it against my multimeter.SighThanks
Measurement of power rail impedance and inductance and plane capacitance - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: February 12, 2025, 05:07:10 am
content: In this online tool (https://pdntool.com/app/), There's a field called power supply (in mohms and nH) and plane capacitance (mohms and uF).I have 2 questions. How does the power supply and plane capacitance impact the graph output and how to find those values in the pre-layout stage?

author: Terry Bites
author_rank: Super Contributor
timestamp: February 14, 2025, 02:21:23 pm
content: A question for the developer I'd say.Ask them why layout considerations have been completely ignored- that can be what makes or breaks your grounding scheme.
Measurement of power supply inductance - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: February 17, 2025, 08:47:36 am
content: In this tool (https://pdntool.com/app/), or any PDN tool for that matter, I understand that the value of plane capacitance can be calculated with the layout stack-up information (Di-electric thickness, overlap area of planes and di-electric overlap area).But, any idea on how to calculate the "power supply inductance" value?

author: MrAl
author_rank: Super Contributor
timestamp: February 17, 2025, 01:01:36 pm
content: Quote from: Freshman on February 17, 2025, 08:47:36 amWhat power supply are you talking about, and where is this inductance located?

author: mtwieg
author_rank: Frequent Contributor
timestamp: February 17, 2025, 01:36:25 pm
content: Quote from: Freshman on February 17, 2025, 08:47:36 amThe power supply impedance is likely to be a very complex, high order transfer function across such a wide frequency range, just like the impedance plots this tool spits out. Very strange that the tool wants to assume the power supply can be modeled as a simple series R+L.A pair of parallel plates (like supply planes) can be described with a capacitance (at least at low frequency), but defining any sort of inductance requires defining a return path for current. And then you'd have to use something like a finite element solver (HFSS, CST, COMSOL, etc) to get a meaningful answer. And if you did, I highly doubt it would fit into a first order R+L model.Honestly I question the utility of such a tool. It will show you nice plots, but I doubt it will actually reflect reality.