hybridfree/eevblog-posts huggingface dataset:
calculating combination circuits for capacitance - Page 1
Forum section: electronics / beginners

author: krayvonk
author_rank: Regular Contributor
timestamp: June 25, 2019, 12:57:06 pm
content: say I have 2 capacitors in parallel, connecting to another capacitor in series.If you compute parallel first, its a completely different result from computing series for each then adding them together.which way is correct?

author: Wimberleytech
author_rank: Super Contributor
timestamp: June 25, 2019, 01:02:54 pm
content: Quote from: krayvonk on June 25, 2019, 12:57:06 pmDo the caps in parallel first.

author: pwlps
author_rank: Frequent Contributor
timestamp: June 25, 2019, 01:11:39 pm
content: Quote from: krayvonk on June 25, 2019, 12:57:06 pmYou can only use the series formula if there is nothing connected in the middle, so you have no choice but to first replace the two parallel caps by their equivalent value and then connect it in series with the third one.
calculating force from strain - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: November 05, 2014, 04:16:31 pm
content: Is it right way to calculate force from known strain & young modulus :1. E = stress / strainfrom where stress is calculated2. Then stress = Force/areaFrom here force can be calculated3. How to convert this force (in newton) into Kg.

author: Andy Watson
author_rank: Super Contributor
timestamp: November 05, 2014, 04:34:32 pm
content: 1. Yes2. Yes3. Divide by 9.8 (on Earth).

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: November 06, 2014, 07:17:11 pm
content: 1. I have square metal plate of .15m.2. I was looking at formula , let say how much Kg-force for 1 microstrain3. material is glass fibre. From below link young modulus of glass fibre is 17Gpahttp://www.engineeringtoolbox.com/young-modulus-d_417.htmlStress = E x strain = 17 * 10^9 * 1 * 10^-6 = 17000Force = Stress * area = 17000 * .15 * .15 = 382.5So kg-force = 382.5 / 9.8 = 39.031. One microstrain produces 39.03Kg force. Such small strain with such high Kg-f Is there any mistake in calculation I am doing?2. My material is glass fibre. Or I have selected wrong young modulus??

author: Andy Watson
author_rank: Super Contributor
timestamp: November 06, 2014, 11:54:44 pm
content: Any chance you could draw a diagram? I'm not following what you are trying to achieve.How are you applying the load? Applying a load through the plate will produce considerably more stress than applying the load as tension. You need to specify how the load is applied and how the plate(s) is supported.
Calculating hysteresis  - Page 1
Forum section: electronics / beginners

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 21, 2019, 11:22:05 pm
content: Hello all,I starting to learn about opamps, comparators to begin with. I want to add a 5mV hysteresis for Low threshold of 1.5v and High threshold of 2.5v. The circuit is to charge supercaps. I got the resistor vlaues with playing around with the LTSpice simulator.Would appreciate if anyone could share the calculation of this circuit including the Hysteresis.

author: Wimberleytech
author_rank: Super Contributor
timestamp: December 22, 2019, 01:27:08 am
content: Are you hoping for 5mV of hysteresis, or 500mV? Post your LTSpice file.Calculating the hysteresis is pretty simple. You have to solve two cases: 1) when the output is high, and 2) when the output is low. In each case calculate what Vin must be in order for the non-inverting input voltage to be 1.3 volts.

author: anishkgt
author_rank: Frequent Contributor
timestamp: December 22, 2019, 01:47:07 am
content: Thank you !From reading couple of app notes of TI i know its all about the Hth and Lth. but can't find anything that explains in simple english. Yes its 500mV not 5mv, sorry !
Calculating inductance for boost converter - units - Page 1
Forum section: electronics / beginners

author: newtekuser
author_rank: Frequent Contributor
timestamp: March 04, 2024, 05:15:32 am
content: Watching Phil's Lab video on calculating the value for the inductor and want to know what units he used to get the 23uH value for the inductor.Vout = 16VVin = 5VEff = 0.8Fsw = 1.5MHzFirst he uses the estimation formula for the inductor ripple current = 0.3 * Iout (max) * Vout/Vin = 96mAThen he feeds the inductor ripple current into the inductance formula (Vin(Vout - Vin) ) / Vout * f * IL = 23uHDoes he express the 1.5MHz frequency as 1.5 and ripple current as 0.096OR1.5MHz frequency as 1.5 and ripple current as 96, then multiplies everything by 1000 ?

author: newtekuser
author_rank: Frequent Contributor
timestamp: March 04, 2024, 05:40:33 am
content: Answering my own question: the frequency value is in MHz and the current ripple is in Ampsso (5 * (16-5)) / 16 * 1.5 * 0.096 = 23uH

author: Berni
author_rank: Super Contributor
timestamp: March 04, 2024, 06:15:36 am
content: You are supposed to put everything into equations as base units. so the 1.5MHz should be 1500000 Hz and the result should be 0.000023 HJust that since Mega is x1000000 and is on the bottom of the fraction so becomes /1000000 and Micro is /1000000 the units just happen to work out in a nice way, letting you work with numbers without a bunch of zeroes.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 04, 2024, 02:07:13 pm
content: I've used this handy tool.https://www.coilcraft.com/en-us/tools/dc-dc-optimizer/#/searchGive up on inches and farenheit.
Calculating inductor value for buck converter using XL1509 IC - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: May 22, 2025, 06:39:29 pm
content: Hello friends, I want to build a Buck converter using a Chinese XL1509 IC. For designing the buck converter, I have taken all the theoretical calculation formulas from the book Power Electronics written by L. Umanand. But the problem now is that the value of the inductor I’m getting using the formulas given in the book is significantly higher compared to the value given in the XL1509 IC datasheet.For example, in the case of a 12V output, if the maximum input voltage is 40V and the minimum input voltage is 4.75V, then the inductance value I get is 352.5 µH, which is quite a bit higher than the value (150 µH) specified in the XL1509 datasheet!Can anyone in this forum help reconcile the discrepancy between the book’s calculation and the datasheet values?Here is the Theoretical Calculation from the power electronics book by L UmanandHere is my Excel file for CalculationHere is my Excel file for calculation.https://docs.google.com/spreadsheets/d/1G3gOypwJzxKFlhouzd6OTIGSwy34eQnq/edit?usp=sharing&ouid=104527294515503795614&rtpof=true&sd=true

author: khatus
author_rank: Regular Contributor
timestamp: May 22, 2025, 07:53:54 pm
content: I observed that changing the ripple current (diL\ΔiL) in the denominator of the inductance equation significantly affects the calculated inductance value. For example, when the ripple current is increased from 1% to 2% of the output current, the required inductance decreases from 352.5 µH to 176.25 µH.

author: jwet
author_rank: Frequent Contributor
timestamp: May 24, 2025, 05:33:00 pm
content: It looks like you have things worked out. I was a FAE for Maxim for a while and had a lot of conversations like this with customers. We gave formulas in our data sheets that often didn't agree with text book examples. These were based on theory but were modified for the specific features of our parts and were often optimized in the lab.Generally text books are written for a generic continuous conduction PWM type buck. Commercial chips have all kind of wrinkles incorporated and slip into non continuous modes, etc. The inductor ripple current (usually over 20%) is a trade off with input and output capacitor values and especially ESR, since they have filter this to the final output. Don't confuse output ripple with inductor ripple current. Keeping inductor ripple current very low creates some strange problems, it will drive the V/L in the inductor lower which will force higher inductance. Higher inductance generally gives you a limited range of min to max output current because you don't have the range to charge the inductor harder. In general I would trust the Manufacturer's recommendations. I would also do some tests of the final circuit before release to see what was going on. An Oscilloscope current probe is a great tool for this.Good luck.
Calculating input ripple voltage to SMPS - Page 1
Forum section: electronics / beginners

author: king.oslo
author_rank: Frequent Contributor
timestamp: January 18, 2012, 08:07:44 am
content: Hello everyoneI thought I would make a SMPS. After rectification of the AC voltage, I need to work out how much capacitance I must add.I found this really nice formula which calculates the capacitance required to reduce to10% rippleoutput. The website says this is a typical requirement:Code:C = (5 × I_out) / (V_out × f)// source: [url=http://www.kpsec.freeuk.com/powersup.htm]www.kpsec.freeuk.com/powersup.htm1. That is great, but I cannot use it directly to get values for 5% or 20% ripple. Which formula should I use to find this?2. When looking at the datasheet of switching controllers; what is maximum input ripple usually called? I can only find V_in: 2V-26V.Thank you.Kind regards,Marius

author: amspire
author_rank: Super Contributor
timestamp: January 18, 2012, 08:34:02 am
content: Lets go to basics. Worst case, the capacitor is charging for almost zero time, and discharging for the rest of the timeThe half cycle period of the mains is 1/2 x 1 / f.I = C x dV/dT (This is the standard formula relating current to rate of change of voltage for a capacitor)So worse case, the capacitor will discharge by dV = (I / C) x dT = I /( C * 2 * f) if you are using a full wave rectifier.Rewriting this, C = I / (dV * 2 * f)dV = Voutx Rf(where Rf= the ripple factor. 10% ripple equals a ripple factor of 0.1)so C = I / ( Vout* Rf* 2 * f )Put in 0.1 for Rfand it matches the equation you found which is good.Richard

author: amspire
author_rank: Super Contributor
timestamp: January 18, 2012, 09:03:58 am
content: In terms of the datasheet, the amount of ripple will be determined by two things.The minimum voltage in has to be above the minimum voltage the regulator needs to operate. So if you had a 12V buck regulator, then the regulator and switching device voltage drops may mean you want at very minimum 13V in.The second thing is there is probably an input rejection ratio spec'ed for the regulator. If it was 40dB, and you wanted the output ripple due to the input ripple to be less then 10mV, then you need the input ripple to be less then 1V p-p.Richard.

author: Psi
author_rank: Super Contributor
timestamp: January 18, 2012, 09:06:12 am
content: You can also use something like LTspice to simulate it and see what the output looks like.It can be a bit confusing using spice at first because there are quite a few options.But once you have your circuit working you can try different value caps with different esr and see what sort of ripple you'll get.
Calculating noise floor from SNR - Page 1
Forum section: electronics / beginners

author: sled
author_rank: Contributor
timestamp: June 30, 2017, 01:55:04 pm
content: Hey there,I'm trying to choose the right LDO for my audio codec circuit without introducing measurable noise. I foundthisarticle from Analog Devices with a sample calculation, so I tried to reproduce their calculations but the numbers won't fit... Maybe I'm overlooking something?Here's the part in question:Quote(Remark: I think 11.26 nVrms should be 11.26 nVrms/rt-Hz in the first sentence..)To my knowledge the SNR is calculated by:SNR = 20*log10(VFS/Vqn)whereVFS= RMS Value of Full Scale InputVqn= RMS Value of Quantization NoiseIn this caseVFS= 2 Vp-p/ (2*sqrt(2)) = 0.707VRMSSolving forVqn= VFS*10-SNR/20= 0.707VRMS*10-78dB/20= 89uVRMSNoise spectral densityN0= Vqn/ sqrt(Fs) = 89uVRMS/sqrt(125.0MHz) = 7.96nVRMS/rt-HzObviously7.96nVRMS/rt-Hzis far away from the mentioned11.26nVRMS/rt-Hzin the articleThanks a lot in advance!Simon

author: bson
author_rank: Unknown
timestamp: July 01, 2017, 06:25:31 am
content: Quote from: sled on June 30, 2017, 01:55:04 pmShould be:89uVRMS/sqrt(125.0MHz/2) = 11.26nVRMS/rt-HzI.e., spectral width is half the sampling rate. (A duh moment I'm sure.)
Calculating Output High voltage for a MCU - Page 1
Forum section: electronics / beginners

author: loudaslife
author_rank: Newbie
timestamp: April 10, 2015, 03:44:25 am
content: I'd like to drive some LEDs, but I don't know what voltage to expect coming from the MCU.The ATmega328 datasheetlists the expected output high voltage on page 314, but only for 4 sets of conditions. Is there any way I can calculate the expected voltage given an arbitrary current and source voltage? Or would I have to resort to actually getting my hands on one to measure?

author: Rufus
author_rank: Super Contributor
timestamp: April 10, 2015, 04:12:47 am
content: The datasheet you linked has plots of typical output pin voltage vs. current.

author: Psi
author_rank: Super Contributor
timestamp: April 10, 2015, 07:52:47 am
content: 5V in 5V out with no load.Worst case with 20mA load you are guaranteed to get more than 4.2V @ 85C.In reality, at room temp and no other pins loaded, you'll probably get ~4.80V at 20mA load.

author: dannyf
author_rank: Super Contributor
timestamp: April 10, 2015, 12:23:08 pm
content: Quote35.7 Pin Driver Strength.Typicall 20-25ohm is a good number and 50ohm is a conservative number.
Calculating power from oscilloscope CSV file - Page 1
Forum section: electronics / beginners

author: omglol
author_rank: Regular Contributor
timestamp: July 16, 2017, 09:16:58 pm
content: I am trying to measure power of the three phase machine using 4-channel oscilloscope and this method:http://teledynelecroy.com/doc/threephase-power-measurements-using-a-fourchannel-scope-to-measure-threephase-powerI used 2 differential probes and 2 current probes, set like this:Channel 1 (Vac): Differential probe, attenuation ratio 1/20, oscilloscope setting 500 mV/divChannel 2 (Vbc): Differential probe, attenuation ratio 1/20, oscilloscope setting 500 mV/divChannel 3 (Ia): Current probe, ratio 10 mV/A, oscilloscope setting 50 mV/divChannel 4 (Ib): Current probe, ratio 10 mV/A, oscilloscope setting 50 mV/divNow I saved (attached) approximately 1.5 period of the waveform as CSV file. What would be the easiest way to calculate power from this data? I have no experience here, please help me.Thank you very much.

author: alm
author_rank: Super Contributor
timestamp: July 17, 2017, 12:43:23 am
content: Your question is not sufficiently specific to understand the nature of your problem. What did you try? What problems did you run into? What information have you found?I would mport the data in a spreadsheet of choice or in MATLAB or whatever you are familiar with. Convert the measured values to real voltage / current values based on attenuation / conversion ratios (so multiply voltage by 20, multiply current by 10 mV/A). Use the equation at the top of that application note to calculate instantaneous power at each point in time, and from that you can calculate the average (arithmetic mean) power across one cycle.If you have a fancy scope, then you should be able to do all of this inside the scope (scale the channels, add and multiply, and cycle mean).

author: joeqsmith
author_rank: Super Contributor
timestamp: July 17, 2017, 01:10:17 am
content: Are you just not understanding the math? Don't know how to use Excel or other tool? Seems like you have everything you need.
Calculating pull-up resistor values for older processors? - Page 1
Forum section: electronics / beginners

author: MarkS
author_rank: Unknown
timestamp: January 26, 2016, 08:54:37 pm
content: Once again, another 68000 question. I know that the processor will need pull-up resistors on both the halt and reset lines. In nearly every reference I can find, from older schematics and books to current retro projects, 2.2K Ohm resistors are used. I've done a Google search on how to determine pull-up resistor values and everything I can find is geared towards today's hardware. The best advice I can find is to size the resistor to be 1/10th the impedance of the pin. With that in mind, I look a the electrical charastics in the datasheet, beginning at page 141:datasheet. Nothing. I cannot find anything that would tell my why 2.2K is the value of choice. There are no impedance values given for any pin and using the input leakage current (the only reasonable data I can see) doesn't lead me anywhere near 2.2K.I'm willing to accept that resistor value and go with it, but for all I know, it was a miscalculation on some project from decades past that found its way into every other project since. I really don't want to accept this without know how it was calculated.

author: Ian.M
author_rank: Super Contributor
timestamp: January 26, 2016, 09:09:58 pm
content: Bus capacitance and desired risetime?

author: MarkS
author_rank: Unknown
timestamp: January 26, 2016, 09:57:36 pm
content: Quote from: Ian.M on January 26, 2016, 09:09:58 pmThat helped! Googling along those lines brought up i2c documentation. While not exactly the same, it gave me formulas I wasn't aware of. Thanks!
Calculating resistor for LED - Page 1
Forum section: electronics / beginners

author: EEBlackSheep
author_rank: Contributor
timestamp: February 01, 2012, 05:37:11 am
content: OK, one of the simple ohms law calculations is to calculate the resistor size for an LED. I ran across this web site describing how to do it:http://www.seattlerobotics.org/guide/electronics.htmlHe has a 6VDC power source, with a 330R resistor and a red LED all in series. He calculates the theoretical current by ignoring the LED and calculating the value for the resistor alone using the total voltage of the circuit. I have seen this before and it make no sense to me. Once the circuit is on, there is a voltage drop across the LED and therefore there will *not* be a full 6V across the resistor. So the current in the circuit will be less than the his calculation.So by my calculation, the red LED will have a 1.9V voltage drop, so 6V-1.9V=4.1V is across the 330R resistor, giving 12.4mA I hooked up a circuit and the experiment agrees.So... am I correct in that his method for calculating the current limiting resistor is flawed?

author: amspire
author_rank: Super Contributor
timestamp: February 01, 2012, 05:40:50 am
content: Both your reasoning and your calculations are perfect.

author: IanB
author_rank: Super Contributor
timestamp: February 01, 2012, 06:25:33 am
content: He is certainly wrong in that article when he says, "The current then flows through the LED, which doesn't have resistance"However, the LED will appear quite bright with 12 mA, hardly less than with 18 mA. So if the LED is just for indication it is quite OK in this case to simplify the calculation and ignore the voltage drop over the LED. The LED will last a bit longer and the battery consumption will be less. Sometimes "good enough" is good enough. The trick is knowing when...

author: Psi
author_rank: Super Contributor
timestamp: February 01, 2012, 06:31:32 am
content: Yeah, you will see people ignoring the LED drop sometimes.It only becomes an issue at low voltages.I guess it's an easier way to explain it to someone with no electronic background.

author: vk6zgo
author_rank: Super Contributor
timestamp: February 01, 2012, 06:33:37 am
content: Quote from: IanB on February 01, 2012, 06:25:33 amExactly what I was going to say!I must admit I usually ignore the LED voltage drop as well.Because the human eye is not linear,there is very little difference in brightness.It gets a bit messier with High Intensity LEDs,though.VK6ZGO

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: February 01, 2012, 11:43:19 am
content: Here are a couple articles I wrote for Digital-DIY after reading a couple horrendous explanations of how to do this.LED CalculationsLED Calculations - The Lab Section
Calculating resolution - Page 1
Forum section: electronics / beginners

author: ElectricGuy
author_rank: Regular Contributor
timestamp: March 06, 2015, 04:06:03 am
content: Hey everyone;Help one on this one, because i'm not getting there alone.I have a system that measures the velocity across two points. Thoses points are separated from each other 30cm.My PIC micro starts a timer when the projectil travels across the first sensor and stops on the second sensor.My Timer is configured to tick every 4uS (8Mhz/4/(1:8 prescaller)-1.In software i'm multiplying my timer value by 4 so i can get the time traveled in uS.So, my velocity in m/s is V=300000/(timervalue*4)All is working fine great, i get the velocity. but now i want to figure the resolution of the system, and i'm not getting there.Can somebody help out?Thank you!

author: KerryW
author_rank: Regular Contributor
timestamp: March 06, 2015, 04:40:54 am
content: Your resolution is 3uS. You probably want to know the resolution in M/S, though. don't you?The resolution in M/S changes with the velocity.1 tick = 75000 M/S, 2 ticks = 37500 M/S, resolution = 37500 M/S10000 ticks = 7.5 M/S, 10001 ticks = 7.49925 M/S, resoluyion = 0.00075 M/S

author: IanB
author_rank: Super Contributor
timestamp: March 06, 2015, 04:46:16 am
content: If you are measuring time intervals, your resolution is 4 µs (the smallest resolvable difference between two measurements is 4 µs).If you are measuring speed, the resolution is a function of the time resolutiondt, the distance between measurement pointssand the speed you are measuring,v. Your speed resolution is given by:dv= [s/t] - [s/ (t+dt)]wheret=s/vhencedv=v* [1 -s/ (s+v*dt)]Therefore the resolution is better at lower speeds, greater distances, and smaller clock intervals.

author: ElectricGuy
author_rank: Regular Contributor
timestamp: March 06, 2015, 04:53:23 am
content: Ok, i understand now. And yes, i want the m/s resolution.Thank you IanB and KerryW.Actually i was getting those values, but didn't understand them.I think for each measure i will calcule and print also the resolution. So i can always know the resolution that i'm getting.

author: babysitter
author_rank: Frequent Contributor
timestamp: March 06, 2015, 05:34:40 am
content: Hi,your resolution with this timing setup will always be the same as long as you don't change one of the contributing values sensor distance or timer settings. I think it would be more interesting to printout the interval you dont know about in m/s, like inSpeed between X1 m/s and X2 m/s. X1 is the corresponding speed according to the timer value, X2 the speed that corresponds to timer-1, as the actual trigger event is inbetween those two, not earlier than timer-1 but before timer.
Calculating the parameters to wind my own inductors - Page 1
Forum section: electronics / beginners

author: nathanpc
author_rank: Unknown
timestamp: September 16, 2015, 12:41:13 pm
content: I'm playing around designing my own switchmode converters using standard inductorslike this, but I want to play around with a bit more current than they are rated, so I decided to wind them my own using some torroidal cores I salvaged from old ATX power supplies. What I'm currently interested is how I can calculate the parameters necessary to wind them, things like the number of turns necessary to get a certain amount of inductance, and specially how much current it's rated at, since I'm pretty sure there are some magnetic limitations to this, not just the gauge of the wire.

author: bktemp
author_rank: Super Contributor
timestamp: September 16, 2015, 12:43:33 pm
content: You can use this tool for all the calculations:http://www.micrometals.com/software_index.html

author: firewalker
author_rank: Super Contributor
timestamp: September 16, 2015, 12:51:20 pm
content: You could also have a look at the "Transformer-and-Inductor-Design-Handbook".Alexander.

author: nathanpc
author_rank: Unknown
timestamp: September 16, 2015, 03:40:46 pm
content: Thanks very much for the quick replies, but are there any other resources available to do this? The Micrometals calculator is extremely difficult to use if you don't know much about the parameters and the handbook is extremely complex and long if I just want to learn the basics to wind my own inductors, in the future I could read it to get a really good theory background.

author: bktemp
author_rank: Super Contributor
timestamp: September 16, 2015, 04:44:13 pm
content: Iron powder cores are not the easiest to use because they have a soft saturation curve and quite high core losses. Therefore the tool really helps much selecting suitable material, size, wire gauge and number of turns.Ferrite cores are probably much easier to calculate.
Calculating the voltage of capacitors - Page 1
Forum section: electronics / beginners

author: microbug
author_rank: Frequent Contributor
timestamp: April 30, 2013, 06:56:57 pm
content: I am a beginner, and when people say things like 'add a small capacitor to the output', I am always a bit stuck. Although I am somewhat familiar with what sort of capacitance I would need, I have no idea about the voltage. This is an example of a schematic - look at C1, C3 and C4, none of which have voltages marked. Should I just use the maximum voltage that I think is likely to be passing through there, say 35V, or is there something I'm missing here?Thanks for any help!

author: c4757p
author_rank: Super Contributor
timestamp: April 30, 2013, 07:00:12 pm
content: Quote from: microbug on April 30, 2013, 06:56:57 pmFTFY, and yes, plus about a 50% safety margin.

author: microbug
author_rank: Frequent Contributor
timestamp: April 30, 2013, 07:01:50 pm
content: OK, thanks! I guess everyone has to start somewhere...

author: Rick Law
author_rank: Super Contributor
timestamp: April 30, 2013, 09:50:20 pm
content: Quote from: c4757p on April 30, 2013, 07:00:12 pmA few weeks ago, I was playing around with (home-made) boost circuit. The chip's spec is 40V, but I grounded the reference by mistake and output went up to 47V. A 50V capacitor literally started steaming... Blew the 50V capacitors within a few seconds of reaching 47V.After I swapped the capacitor, I quickly modified my output-adjustment voltage divider so that it will not go beyond 30V with my new 50V-capacitors.Yeah, leave some safety margin.

author: c4757p
author_rank: Super Contributor
timestamp: April 30, 2013, 09:57:19 pm
content: A 50V capacitor might not behappywith 47V, but it shouldn't start steaming! That could be ripple current. If your circuit is pushing large current spikes through the capacitor, its ESR will heat up. That's why DC-DC circuits typically use low ESR capacitors.

author: AcousticBruce
author_rank: Contributor
timestamp: April 30, 2013, 10:02:45 pm
content: Quote from: c4757p on April 30, 2013, 09:57:19 pmAnd this would be the point where a cheap DSO might not catch the spikes? This all depends on the speed of the spike though.

author: Rick Law
author_rank: Super Contributor
timestamp: April 30, 2013, 10:11:10 pm
content: Quote from: AcousticBruce on April 30, 2013, 10:02:45 pmInteresting! I learn something new from both of you.
Calculating Thevenin Voltage by superposition - Page 1
Forum section: electronics / beginners

author: markusz
author_rank: Contributor
timestamp: January 10, 2022, 01:43:53 am
content: Hi experts,I'm calculating Thevenin Voltage by superposition, and the whole process can be seen in the attached picture.To sum it up:The circuit has one Voltage source and one Current sourceBy superposition, I can take the sources one by oneFirst, I take Voltage source and open the Current sourceNext, I take the Current source and short the Voltage sourceFinally I add them up.The right answer is V_thev = V*R2/(R1+R2) - I0 * R3. I got the first part correct but the second part wrong.Can you please let me know where did I go wrong? Thanks!

author: ledtester
author_rank: Super Contributor
timestamp: January 10, 2022, 02:15:10 am
content: Working backwards you can see that your step 1 is correct, so your problem is in step 2.Hint: no current flows through R1 or R2. All of I_0 flows through R3 and back into the current source.The circular arrow in the middle isn't valid since it doesn't represent a circuit.

author: markusz
author_rank: Contributor
timestamp: January 10, 2022, 02:29:52 am
content: Quote from: ledtester on January 10, 2022, 02:15:10 amThanks for the tip, I think I get the idea: If I look at the node south of the current source (call it B), using KCL, so apparently the current coming into the node (from R3) is I0, and the current coming through the source is also I0, which means there is 0 amp going to R1 and R2.I'm also reading node analysis and it says I can ground any node and it shouldn't affect the outcome. I guess if I ground node B this becomes more obvious.
Calculating Three phase power conversion 220V@200A to standard 220V AC - Page 1
Forum section: electronics / beginners

author: ApplePi
author_rank: Contributor
timestamp: August 20, 2013, 04:29:01 pm
content: As it says in the title I'm trying to calculate the max current if I convert the Three phase 220V@200A to 220VAC or 120VAC. I've been trying to find information and I can't seem to find anything anywhere.

author: PuterGeek
author_rank: Regular Contributor
timestamp: August 20, 2013, 04:41:57 pm
content: I'm a little confused about what you are trying to do.If you mean the maximumsingle phasecurrent you can get, you can only use one phase and it would be 200A (of which you could us 80% or 160A continuious). If you want to drop the voltage to 120V you will lose some power in the transformer so you would get less than 320A (probably 300A or less). The power company will prabably be unhappy with you if the other legs aren't equally loaded.If you are trying to combine all of the phases to single phase you will have to use a power converter such as a motor generator. The maximum continous input current will be 80% and the output will depend on the efficncy of the converter.Hope that helps.

author: AlfBaz
author_rank: Super Contributor
timestamp: August 20, 2013, 04:55:23 pm
content: You are not providing enough infoIf you want to replace a 3 phase machine with a single phase machine and still have it deliver/consume the same power then calculate 3 phase power then use that value to determine the current required for single phase

author: ApplePi
author_rank: Contributor
timestamp: August 20, 2013, 04:56:52 pm
content: I need to convert 3phase 220v power to standard 220v power for Servers

author: dr.diesel
author_rank: Super Contributor
timestamp: August 20, 2013, 05:00:46 pm
content: Servers don't use 3-phase power directly. You'll need to measure/amp clamp each phase separately (will likely not be balanced) to determine the current use, plan for the future, then spec.

author: PuterGeek
author_rank: Regular Contributor
timestamp: August 20, 2013, 05:29:58 pm
content: Quote from: ApplePi on August 20, 2013, 04:56:52 pmFirst, a clarification; three phase power in the US is normally wired as Y (wye) at 480V or 240V. Industrial 480V is sometimes wired as delta which would require transformers. Delta three phase is normally only used for production facilities so it is unlikely.Each leg of 480V is 277VAC to neutral and would require transformers to drop the voltage. Each leg of 240V is 120V to neutral and 208V between any two legs.You can run the servers at 120V off single phase breaker. You can run the servers off two phase breakers if their nameplate says they can operate at 208V.
Calculating Watt & Watt-hour consumed from battery  - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 04, 2018, 04:50:43 am
content: 1. I have a data logger for 48V battery which takes reading every 1 second of voltage & current & store it in a file.2. Reading is something like this:a) 47.4V, 50Ab) 47.3V, 49.4A....and so on until battery discharges completely in one hour.3. How to calculate Watt & Watt hour consumed from it over hourNormally if voltage is same, I calculate by difference of current between two multiply by voltage.But in this case voltage is also reducing(during discharge) & going up during charge.How to do the calculations of Watt & Watt/hour in it, should I take average of voltage over period of time & multiply by current difference?

author: maukka
author_rank: Unknown
timestamp: February 04, 2018, 08:50:10 am
content: DC watts are simply voltage*current.Watt-hours are integrated over time so if you have a 1 second sampling rate you add each reading cumulatively to the previous like this:47.4V*50A*1/3600h=0.658Wh0.658Wh+47.3V*49.4A*1/3600h=0.658Wh+0.649Wh=1.307Wh

author: Dave
author_rank: Super Contributor
timestamp: February 04, 2018, 11:51:32 am
content: Alternatively, you should consider using trapezoidal integration, especially if your measurements are more sparse.You take the mean of two consecutive measurements and multiply it by the time between those two samples.

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 06, 2018, 02:46:00 am
content: trapezoidal integration works fine
Calculation of current in a AC circuit - Page 1
Forum section: electronics / beginners

author: Bryan
author_rank: Frequent Contributor
timestamp: April 28, 2014, 08:26:49 am
content: All:Ok, probably a dumb question but looking at the values of the resistors R2-R3-R4 in this circuit I am not sure how the author is getting the current values of 10ma,1ma and 0.1ma . I suppose being AC there is a difference.http://www.next.gr/meter-counter/meters/Simple-Curve-Tracer-Circuit-l14760.html

author: lewis
author_rank: Frequent Contributor
timestamp: April 28, 2014, 09:11:06 am
content: It's in milliamperes per volt. Current equals voltage divided by resistance. So at 1V, the current through the 100R is 10mA, through 1k is 1mA and through 10K is 0.1mA.The currents are RMS values, which is generally how AC current is measured. It's the "DC equivalent" current.

author: Bryan
author_rank: Frequent Contributor
timestamp: April 28, 2014, 09:18:19 am
content: Ah, that's right per it's ma/volt. Thanks, missed that.
Calculations for ESC - Resistor Divider Network - Page 1
Forum section: electronics / beginners

author: ripper_pc
author_rank: Newbie
timestamp: September 07, 2019, 09:47:40 am
content: I am curious as to the calculations behind this:https://simple-circuit.com/wp-content/uploads/2018/03/pic16f887-brushless-motor-controller-esc.png(See Capture.png)Example; If the MCU works on 3.3V;1 - Till what value of the Motor Battery Voltage is this resistor divider good.(Do we just take into account ex: R1 and R6 as voltage dividers to calculate the output voltage of the divider for BEMF sensing?)2 - Alternatively; if I want to run the motor at a higher voltage; which part of the voltage divider do I change ?(Is it okay to add a Diode to Vdd (MCU) to limit any potential damage to the MCU from higher voltages)3 - What would happen if R7;R8;R9 were reduced to 10K ?Thanks!
Calculator to find multiple standard capacitors to achieve specific value - Page 1
Forum section: electronics / beginners

author: ricko_uk
author_rank: Super Contributor
timestamp: December 06, 2019, 11:25:29 pm
content: Hi,I need a calculator to find how many and which standard-value capacitors I need to connect together (series and/or parallel) to achieve specific (unusual and non-standard) target capacitance values.I came across one a while back but couldn't find it anymore. Do you know where I can find one?Thanks

author: ebclr
author_rank: Super Contributor
timestamp: December 07, 2019, 11:58:11 am
content: "Maybe" you find something useful herehttps://www.digikey.com/en/resources/online-conversion-calculators

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 07, 2019, 12:00:10 pm
content: Use a resistor calculator and invert the topology (series <--> parallel).Tim

author: artag
author_rank: Super Contributor
timestamp: December 07, 2019, 12:16:02 pm
content: Bear in mind that most capacitors have huge tolerances - 20% easily, and electrolytics can be -50,+100%.This means firstly, that assembling a capacitor from other values may not be as accurate as you expect : if you're trying to get less than a 10% change you may already be there !Secondly, except in special cases, circuit designers try to avoid a need for accurate capacitance values. So in may cases you can fit something that's 50% out and it will still work OK.
Calibrate CNY70 reflective optical sensor - Page 1
Forum section: electronics / beginners

author: jbs
author_rank: Contributor
timestamp: May 20, 2020, 12:19:55 pm
content: Hi,I have a CNY70 sensor which I use in my project.I want the sensor to give out the same value when I hold my finger 1 cm in front of it. However, depending on whether I use it during the day (daylight) or during the evening (artificial light) it gives me different readings.How can I resolve this problem?Thanks,Joël
Calibrate RTCC as accurately as possible - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: April 16, 2020, 09:51:33 am
content: Hi.I recently put together an RTCC project, using aMCP79410rtcc chip, which I will use in a battery-powered situation with an attiny.But that's not important. What I'd like to do is to accurately perform the calibration procedure, in order to have the best possible accuracy (I know that temperature and other stuff will influence the crystal frequency but in principle I should be able to do it). The RTCC anyway supports trimming down to +-1ppm.I thought of enabling the sqw output (as suggested on the 1Hz value) and then measure the frequency over time to establish how much to correctThe problem is twofold though:the compensation of the clock trimming is applied once a minute. I then need several minutes measurements to have a valid valueI don't know what instruments I have that can measure frequencies or time periods with a 1ppm accuracy. (if a specific instrument is needed I can spend as much as 100€ perhaps but I cannot afford more)regarding 2. I only have an arduino uno (which I'm using now to program the clock), a BluePill, a Siglent SDS-1104X-E (which is not accurate enough), a TinyFPGA BX (that I don't know how to use) and basically nothing else.How should I approach the problem? Can I solve it with what I have?Thanks for the help.
Calibrated RF power sensor reference cal factor question - Page 1
Forum section: electronics / beginners

author: route20
author_rank: Newbie
timestamp: April 06, 2023, 07:23:17 pm
content: I'm setting up a modest RF lab at home and purchased a 437B meter with freshly calibrated 8482A sensor. The vendor (who also performs the calibration) provides a current cal factor table for the sensor. The printed reference cal factor is 99% (suggesting the cal factor at 50MHz is 99%). The printed cal factors for 30MHz and 100MHz are 98.9% and 98.7%, respectively. These interpolate to 98.8% at 50MHz. Shouldn't the reference cal factor be 98.8% in this case? Or am I misunderstanding something? I use (way newer) gear like this at work but those are calibrated by the metrology guys and the data stored in memory in the heads themselves, so I rarely have to think about the cal factors.Yes, it's a small amount and the reading would be in spec either way (off by 0.01dB/0.002mW), I'm mostly just trying to understand the why of it.

author: alm
author_rank: Super Contributor
timestamp: April 06, 2023, 08:12:05 pm
content: I've seen this before where the cal factor for 50 MHz is not between 30 Mhz and 100 MHz, or on any kind of smooth line through the other points. I guess it could be uncertainty in the calibration (the measurement uncertainty of the 8482A is in the 1.2% ballpark), or maybe the calibration at 50 MHz is done another way than the other frequencies? Either way, I'd use the reference call factor (99%) to adjust the sensor to the 50 MHz reference.
calibrating a counter - Page 1
Forum section: electronics / beginners

author: ME
author_rank: Frequent Contributor
timestamp: February 27, 2025, 08:38:30 am
content: I have ordered a GPS 10Mhz Disciplined Oscillator, its listed as having a square wave output, Will that be good for calibrating frequency counters or do i need to filter it into a sine wave?, thanks.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 27, 2025, 09:32:09 am
content: A square wave should be fine for a frequency counter. It would only be in the microwave range that too much harminics could cause problems, like measureing the frequency of an harmonic.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: February 27, 2025, 11:10:15 am
content: It should be fine, although some frequency counters may give erratic readings on high Voltage square waves. If you have a problem, a band pass filter will turn your square wave into a sine wave. eBay UK item 294657191023 is one example.SJ

author: benj38
author_rank: Frequent Contributor
timestamp: February 27, 2025, 02:21:07 pm
content: I have yet to encounter a frequency counter that will be confused by a 10MHz square wave from a GPSDO. If yours does, consider buying a lottery ticket the same day, because you are beating the odds

author: tggzzz
author_rank: Super Contributor
timestamp: February 27, 2025, 02:25:39 pm
content: Quote from: Solder_Junkie on February 27, 2025, 11:10:15 amWhy would anybody put a 240V signal into a frequency counter?Hint: look under my moniker.

author: edpalmer42
author_rank: Super Contributor
timestamp: February 27, 2025, 05:23:56 pm
content: Make sure that the triggering controls on the counter are set appropriately for the signal coming from the GPSDO.Typically, the output of the GPSDO will be CMOS levels, i.e. ~5V and ~0V. Check this on a scope. Also make sure that the rise and fall times are nice and clean. Then set the counter for DC triggering at a voltage of ~ 2V5. Use 50 ohm coupling if the GPSDO allows it.If you notice that the reading is always up and down over a tight range you might have external noise messing with the counter. I usually use a low pass filter to remove interference from local high-power FM stations.
Calibrating a Hakko 939 (Anyone familiar with this?) - Page 1
Forum section: electronics / beginners

author: Fizbin
author_rank: Newbie
timestamp: January 24, 2016, 12:37:51 am
content: I'm installing a new tip on my 903 iron for my 939. There seems to be two methods for calibration. One method is using a tip thermometer. Another method, (or perhaps this method is in conjunction with the tip thermometer) you have to take the offset temp that's printed on the tip, etc ,etc.So do I have to perform both methods? Can I just measure the tip? Yes, you can tell I'm a beginner.

author: Shock
author_rank: Super Contributor
timestamp: January 24, 2016, 11:57:42 am
content: You normally do one or the other.Not sure if you're using multiple tips but if it is the same genuine Hakko tip type and things are still working fine no need to calibrate at all. If your new tip does have an offset listed though and youhave notcalibrated your station before, it's fine to start using the new offset. e.g. crank it up the heat +10 degrees or whatever it says for that tip.If you don't have a thermometer and are on a budget they sell clone Hakko FG-100 for $15 or so on ebay, celsius only I think so if you can live with that it's a bargain.When you calibrate the station you can calibrate it either to an offset tip or a tip that has no offset, it's up to you and depends how much tip swapping you do. Calibrating to an offset tip would mean if you put a non-offset tip in the iron you would need to adjust the station to cancel out the offset.If your station supports presets you can set up presets as offsets. e.g. a +10 degree setting for a specific tip. Hope you can wrap your head around this.

author: Fizbin
author_rank: Newbie
timestamp: February 12, 2016, 01:27:35 pm
content: Lost track of this thread and my post. Anyway, thanks very much!
Calibrating a solder station - Page 1
Forum section: electronics / beginners

author: tony3d
author_rank: Frequent Contributor
timestamp: November 03, 2013, 03:38:25 pm
content: I noticed that almost all these solder stations have a procedure for calibrating the temperature. Is it safe to use a multimeter to calibrate a solder station? Will the high temps damage the thermocouple?

author: chiefengineer
author_rank: Newbie
timestamp: November 03, 2013, 04:33:14 pm
content: A standard type K-thermocouple survives 1000 °C no problems at all, so don´t worryThe tip of your iron is maybe mains earth, but this should´t be a problem if you probe it with a multimeter with thermocouple.But is there really a need to calibrate a soldering station?

author: Rufus
author_rank: Super Contributor
timestamp: November 03, 2013, 05:05:16 pm
content: Quote from: tony3d on November 03, 2013, 03:38:25 pmThe need to calibrate a soldering iron is debatable.A K type thermocouple is good for the temperature, the insulation it is wired with may not be. Getting good thermal contact may be an issue. The commercial tip thermometers have fine wire thermocouples with a little bit of metal crimped over the junction, that metal wets easily. I have a couple of the fake Hakko tip thermometers you can get on ebay for like $10. I am quite impressed with them, you get a pack of 10 thermocouples and if you don't trust the internal meter you can clip an external K type thermometer on to the thermocouple posts.

author: pickle9000
author_rank: Super Contributor
timestamp: November 03, 2013, 05:49:31 pm
content: Hakko makes a cheap tip tester. Nothing wrong with using a multimeter probe but use one with minimal mass. Also note that the tip temp will vary with the mass and shape of the tip and calibrating each time you change a tip is not really done. Knowing your tip temp is a good thing but most people will have a few favorite temps with one tip and use those 95% of the time. As a general rule "If you ask yourself the question then act on it". Is my iron to hot? Then check it.http://www.ebay.ca/itm/HAKKO-FG-100-iron-thermometer-measurement-solder-iron-temperature-tester-/160980265854?pt=LH_DefaultDomain_0&hash=item257b2beb7e

author: M. András
author_rank: Super Contributor
timestamp: November 03, 2013, 05:57:27 pm
content: hehe thats a fake one, the real is over 300bucks

author: Shock
author_rank: Super Contributor
timestamp: November 04, 2013, 02:04:02 am
content: Ah nice little tool just brought one to play with. Some sellers don't ship the sensors.

author: pickle9000
author_rank: Super Contributor
timestamp: November 04, 2013, 02:19:18 am
content: I actually bought mine locally but yea it looks like a knock off. In any case it's over a year old, don't use it much but seems to work fine. The TC's are very tiny and fast acting. The display looks identical to the real one (maybe it is the same). The price difference is crazy.

author: M. András
author_rank: Super Contributor
timestamp: November 04, 2013, 05:17:18 pm
content: i have a clone too its accurate so no problems. it was a cheaper option then the weller service center....
Calibrating FX-888 - Page 1
Forum section: electronics / beginners

author: ABCD
author_rank: Contributor
timestamp: January 26, 2013, 02:13:06 am
content: How do you check that the dialed up temperature is what the iron is putting out? There's the calibration screw on the temp knob, but what do you use to measure the temp at the tip?

author: IanB
author_rank: Super Contributor
timestamp: January 26, 2013, 02:20:37 am
content: A tip thermometer:But honestly, it isn't worth it for home users. Just adjust the temperature dial to suit your working conditions. The solder should flow easily and quickly on joints, but the flux should smoke as little as possible and not char or burn.