hybridfree/eevblog-posts huggingface dataset:
Parallel capacitors? - Page 1
Forum section: electronics / beginners

author: Fantasma25
author_rank: Regular Contributor
timestamp: February 26, 2014, 01:37:36 am
content: Why so many circuit designs have two or three or more small capacitors in parallel between VCC and GND instead of having just medium one? I'm talking about something like this. Thank you!

author: c4757p
author_rank: Super Contributor
timestamp: February 26, 2014, 01:42:32 am
content: Decoupling capacitors. The traces delivering power to the chip will have some inductance, so if it takes a sudden gulp of current, the voltage at the power pin will drop. A capacitor is put very close to each power pin to provide a local store of power to counteract this.Another reason to parallel capacitors is that smaller capacitors typically perform better at high frequency. If you need 100uF, but you need it to work up to high frequency, you'll have to put some small ceramic capacitors next to the big electrolytic capacitor.

author: Fantasma25
author_rank: Regular Contributor
timestamp: February 26, 2014, 01:50:05 am
content: Quote from: c4757p on February 26, 2014, 01:42:32 amThank you! Now I get it
Parallel Compensation - Page 1
Forum section: electronics / beginners

author: promach
author_rank: Frequent Contributor
timestamp: February 25, 2018, 04:40:06 am
content: How do I derive expressions 4-4 and 4-5 for the two additional poles and zeroes due to parallel compensation (Rc and Cc) ?I have derived the equivalent impedance , but I still could not obtain expressions (4-4 and 4-5)

author: danadak
author_rank: Super Contributor
timestamp: February 25, 2018, 12:17:48 pm
content: Quick method is to use parallel to series and series to paralleltransform to evaluate zero - pole. Note the circuit is complicatedbecause of the effects the amplifier has on the RC networks,eg. the reflected impedance nature of gain. At least in this instancethere is no feedback Z component due to Ccb of the transistor,"Miller Capacitance" effect.http://www.daycounter.com/Calculators/Parallel-Series-Imedance-Conversion-Calculator.phtmlhttp://www.phys.ufl.edu/~majewski/nqr/reference2015/nqr_detection_educational/The%20Series%20to%20Parallel%20Impedance%20Transformation.pdfhttps://en.wikipedia.org/wiki/Equivalent_impedance_transformsRegards, Dana.
Parallel diodes for reduced Vfd? - Page 1
Forum section: electronics / beginners

author: johm
author_rank: Contributor
timestamp: September 06, 2016, 09:59:51 am
content: Is it a good design practice to place two or more germanium diodes in parallel to achieve a lower forward voltage drop? Does increased capacitance limit bandwidth? Is therefore more current needed to bias them properly?Thank you

author: tggzzz
author_rank: Super Contributor
timestamp: September 06, 2016, 10:02:50 am
content: Quote from: johm on September 06, 2016, 09:59:51 amWith putting anything in parallel (cells, resistors, diodes, transistors, etc) the problem is ensuring the current is shared equally between unequal devices.With putting anything in series (cells, resistors, diodes, transistors, etc) the problem is ensuring the voltage is shared equally between unequal devices.How you acheive that depends on the specific application and its requirements. (Numerical requirements, no adjectives allowed : )

author: JPortici
author_rank: Super Contributor
timestamp: September 06, 2016, 11:05:09 am
content: No. two diodes does not have the same forward voltage for a given current. one will conduct more than the otherfor example: LEDs in parallel.If you need a lower Vf use a different diode technology (schottky) or use an opamp as a precision rectifier

author: danadak
author_rank: Super Contributor
timestamp: September 06, 2016, 11:09:51 am
content: Is it a good design practice to place two or more germanium diodes in parallel to achieve a lower forward voltage drop?Its possible that splitting up current would yield lower Vfd, but real issue is significant diode to diodethreshold voltage match. The only way around that would be to screen / bin diodes for matching.Does increased capacitance limit bandwidth?Depends on circuit design, how the diode is being used. Cannot make a categorical statement here.Is therefore more current needed to bias them properly?No, not necessarily.Regards, Dana.
Parallel inverter kits PCB type - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: June 12, 2021, 01:36:54 pm
content: 1. I have a 12V battery for which I need inverter of 220Vac, 600Watts or higher2. Want that each 12V battery would have one inverter PCB & if user want to parallel batteries, PCB module can also enable to parallel the inverters so that I can now combine take 1200W load from inverter. Similarly upto 5 parallel batteries.3. Searchedhttps://www.growatt-america.com/list-8.htmlhas this solution, but they are in complete case, I am looking for indivual PCB board, which I connect inside my big electrical box.4. Is there any such inverter PCB manufacturer?
Parallel magnets - Page 1
Forum section: electronics / beginners

author: PlainName
author_rank: Super Contributor
timestamp: March 02, 2023, 03:40:11 pm
content: I will be using a pair of magnets to attach a small box to a metal rail (think work light sticking to bench support). The magnets, fairly strong but small ones of about 3-5mm diameter will be perhaps 25-30mm apart.Does it matter what polarity the magnets are in respect to each other? That is, would there be a difference if both had their north pole facing the metal, or if they had opposite poles?

author: Xena E
author_rank: Frequent Contributor
timestamp: March 02, 2023, 05:33:33 pm
content: If theres a magnetic path through the magnets, even via your device and the item they are attached to, then they should be opposite so as to act as keeper. A lot of cup magnets made from rare earth metals designed for the task are actually N and S on the atachment face and are therefore complete magnetic circuits when placed on a magnetic surface in their own right.

author: PlainName
author_rank: Super Contributor
timestamp: March 02, 2023, 06:10:01 pm
content: QuoteAh! Didn't know that but it makes sense, thanks.Umm... so my follow-on is: what about three magnets? I guess there is no perfect way, but one of them being the opposite polarity would be better than all the same?

author: Xena E
author_rank: Frequent Contributor
timestamp: March 03, 2023, 05:43:45 pm
content: If mounted 'in line' just alternate polarity.
Parallel or serial connection to a single power supply? - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: September 17, 2020, 03:32:48 pm
content: I have tried to read, simulate and trawled YouTube thin but do not think I have found the right answer.Below do you find 7 circuits, 3 current sources and 1 power supply with 1 positive and 1 neutral.Some uses X amount of current, other Y amount and so on and one does use Voltage.I imagine that one current source have to configured to drive those with same current usage.How would you connect the letters? I have tried to simulate but gets different answers and the math do fast go sour for me.I can't decide what has to be in parallel or series.

author: Ian.M
author_rank: Super Contributor
timestamp: September 17, 2020, 03:40:50 pm
content: You wouldn't.As drawn, its incomplete as each load needs two terminals, as do the current sources, and if you are putting loads that require a constant current in series in real life you need to have some idea of their voltage drop so you can check if the combo will be in the voltage compliance range of your current source.

author: FriedMule
author_rank: Frequent Contributor
timestamp: September 17, 2020, 03:50:50 pm
content: Yes I think I understand. You have the positive lead going trough a current source to a circuit and then back to zero. So in the end, every current source is connected to the positive, each current source is connected to one or more loads and each load is then connected to ground.Hope it explains things?

author: Ian.M
author_rank: Super Contributor
timestamp: September 17, 2020, 04:40:50 pm
content: Nope. You need to put loads that require the same current in SERIES like a string of (dumb) LEDs. If you put them in parallel, the current will be split depending on their operating voltage vs current characteristic, and either one will hog all the current or neither will get the correct current.Otherwise the arrangement of current sources and loads is generally correct.

author: FriedMule
author_rank: Frequent Contributor
timestamp: September 17, 2020, 04:51:09 pm
content: SoE and F in parallel on DG and H in parallel on BI on A?How would you connect D, B, A and J to the transformer?

author: Ian.M
author_rank: Super Contributor
timestamp: September 17, 2020, 04:56:47 pm
content: Nope. E, F and D all in series, G, H and B all in series, then put all the branches in parallel between the supply and ground.

author: FriedMule
author_rank: Frequent Contributor
timestamp: September 17, 2020, 05:15:09 pm
content: So like this? :-)

author: Ian.M
author_rank: Super Contributor
timestamp: September 17, 2020, 06:41:15 pm
content: Looks OK

author: FriedMule
author_rank: Frequent Contributor
timestamp: September 17, 2020, 09:42:48 pm
content: Fantastic, thank you a lot!!
Parallel Port in C#  - Page 1
Forum section: electronics / beginners

author: abdullahseba
author_rank: Frequent Contributor
timestamp: June 15, 2015, 11:11:25 am
content: Is there any C# library or DLL that can send highs and lows to a parallel Port on windows 7?

author: kolonelkadat
author_rank: Regular Contributor
timestamp: June 15, 2015, 01:53:55 pm
content: There is no built-in .NET Framework class for parallel port I/O, although there is a SerialPort class for the serial port.you might find you can p/invoke DriverLinx PortIO if you run your program in Windows XP compatibility mode. but thats just a guess.

author: abdullahseba
author_rank: Frequent Contributor
timestamp: June 15, 2015, 02:02:09 pm
content: Quote from: kolonelkadat on June 15, 2015, 01:53:55 pmBut has someone else developed one?

author: mikerj
author_rank: Super Contributor
timestamp: June 15, 2015, 02:14:03 pm
content: You can try theIONETcontrol, but this is effectively a wrapper around the DriverLinx PortIO driver, so you have to install that first.

author: abdullahseba
author_rank: Frequent Contributor
timestamp: June 15, 2015, 03:02:50 pm
content: Quote from: mikerj on June 15, 2015, 02:14:03 pmthanks

author: JoeN
author_rank: Frequent Contributor
timestamp: June 15, 2015, 05:57:34 pm
content: Doing a Google search I found this straight away...http://www.codeproject.com/Tips/441815/Parallel-Port-Control-with-Csharp-NEThttp://www.codeproject.com/Articles/20545/I-O-Ports-Programming-Parallel-port-Reading-Writin#CommunicatingwiththeParallelPort1Not sure how well it works or if it works with Windows 7 - I don't even have a computer with a parallel port hooked up right now. Maybe give it a spin and see if it works for you.

author: abdullahseba
author_rank: Frequent Contributor
timestamp: June 15, 2015, 06:37:43 pm
content: Quote from: JoeN on June 15, 2015, 05:57:34 pmThanks, I'll give it a go.
Parallel RLC circuit with no Resistor - Page 1
Forum section: electronics / beginners

author: JOJOElectro29
author_rank: Contributor
timestamp: May 15, 2025, 01:28:33 pm
content: Hi, I attempted this problem but am confused with the answer here. not sure why the Wd is 0.25 and not 0.5.

author: jwet
author_rank: Frequent Contributor
timestamp: May 15, 2025, 04:27:42 pm
content: You're rightw^2 is 1/4 but w is 1/2w^2 = 1/LC = 1/(20 x .2)= 1/4, so w= 1/2
Parallel RLC circuit - Page 1
Forum section: electronics / beginners

author: miketan3904
author_rank: Contributor
timestamp: October 06, 2020, 11:58:20 am
content: Hi, I am here to ask for help for my homework. I am trying to obtain the frequency response of the source current a RLC circuit in multisim but the simulation results seems to be wrong.Here's the circuit that I used for simulation:The AC analysis amplitude of the source is set to 5A.And here's the simulation result:I have tried to calculate the total impedance a various frequencies and below are my calculations:@1Hz,XL= 0.57 ohmXC= 1591.55 ohmZtotal= 1.15 ∠ 29.65° ohm@53.05Hz (this is the resonant frequency that I measured from the frequency response),XL= 29.98 ohmXC= 30 ohmZtotal= 899.72 ∠ -0.76° ohm@1kHz,XL= 565.49 ohmXC= 1.59 ohmZtotal= 1.59 ∠ -90° ohmFrom the calculations above, the source current is minimum at resonant and it should not peak up at resonant frequency. So, I would like to ask if my concept is wrong or I did some mistakes in my simulation?Thanks in advance.

author: Andy Watson
author_rank: Super Contributor
timestamp: October 06, 2020, 01:20:32 pm
content: Quote from: miketan3904 on October 06, 2020, 11:58:20 amThe source current is fixed. Remember (?) you set it to 5A.The impedance, and hence the voltage, will peak at resonance.I think you need to refine the frequency step size in your simulation - it is missing the peak.
Parallel & serial LC filter interchaneable? - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: August 10, 2018, 07:52:10 pm
content: I read in book that parallel and series LC resonator,can be both used as bandpass filter.This seems weird becose I read parallel LC resonator is band reject filter,not a bandpass filter.Can you somehow make parallel LC resonator to act like bandpass filter? I take this one step further,can you make series LC resonator act like band reject filter?

author: Benta
author_rank: Super Contributor
timestamp: August 10, 2018, 08:18:15 pm
content: The impedance of a parallel LC connection goes towards infinity at resonance, a series LC connection goes towards zero. I leave it up to you to connect the dots...
Parallel to Parallel shift register for Sega genesis decoder - Page 1
Forum section: electronics / beginners

author: PotatoBox
author_rank: Regular Contributor
timestamp: February 23, 2022, 01:03:18 am
content: In an attempt of saving money and trying to use up the hoard of electronics I already have, I've begun designing a Sega Genesis 6-button controller decoder with TTL logic rather than using a microcontroller. I think I have a pretty good idea on how to do this and the protocol is relatively simplehttps://www.raspberryfield.life/2019/03/25/sega-mega-drive-genesis-6-button-xyz-controller/.But I've been trying to find a Parallel to Parallel shift register to use as a way to capture the outputs of the logic circuitry, store them and then latch them to the output of my decoder. I've found the cd40194, but that is only 4 bits and I was hoping there'd be a shift register within the 74hc family. That and I'd need at least 3 cd40194, since my output has 11 pins (6 buttons + 4 directional + start). I'm looking and I can't seem to find one.

author: sleemanj
author_rank: Super Contributor
timestamp: February 23, 2022, 01:57:47 am
content: Not entirely sure I follow your requirements, but maybehttps://www.ti.com/lit/ds/symlink/cy74fct2573t.pdf8 latched bits.(which was the first useful google result for "latched buffer IC")

author: Buriedcode
author_rank: Super Contributor
timestamp: February 23, 2022, 02:39:19 am
content: Quote from: PotatoBox on February 23, 2022, 01:03:18 amFrom the sounds of it you could either use a 373 or 573 (easier pinout), that is an 8 bit latch - you latch it, so its outputs are set to whatever teh inputs were at the time of latch, whilst the input changes, so you can keep a snapshot of what the 8-bit bus was before it changed.Or using two 8-bit D register, like the 574, daisy chained, so 8 2-bit serial shift registers. I don't think you're going to find one a one chip solution that isn't either a microcontroller, or programmable logic (FPGA/CPLD). Trying to find obscure/rare TTL/CMOS logic chips can be frustrating.Both above solutions have 16 outputs, the first being reading the inputs directly, and read the previous state on the latch, the second would store each 8-bits on both shift registers. You could also read the inputs to the shift registers, so thats 24-bits.As I assume you're providing the select line you can control the latch/clock of the registers between changing the select line.

author: PotatoBox
author_rank: Regular Contributor
timestamp: February 23, 2022, 01:29:22 pm
content: I'll give those chips a look. Admittedly I'll have to place an order for them from digikey regardless for them, which defeats the purpose of this sort of. Oh well. At least I'm still using my existing stock of 74-series logic already.
Parallel two voltage source - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: May 10, 2021, 12:02:33 pm
content: 1. Need to have two parallel "Mobile power bank" outputs. Each voltage source can max supply 5V/2.4Amps.2. Load can vary from 0Amps to 4.8Amps.3. Load sharing need not to be equal, but each voltage source max current has to be limited to max 2.4Amps.4.I tried LTC4415 ? Tried simualting in LTspice. But its shows 3V output at 4AMps load, where each voltage source is 5V. What am i doing wrong here?5. Also its a cost sensitive application, if anything more cost effective is available then please suggest that also.

author: Zero999
author_rank: Super Contributor
timestamp: May 10, 2021, 12:31:17 pm
content: Quote from: Vindhyachal.takniki on May 10, 2021, 12:02:33 pmTake another look at the data sheet.___EN2 is active low and you have it tied to 5V, which disables it, meaning power is only drawn from V1.https://www.analog.com/media/en/technical-documentation/data-sheets/4415fa.pdf

author: Capernicus
author_rank: Frequent Contributor
timestamp: May 10, 2021, 01:22:18 pm
content: You can do it from 2 capacitor banks, instead of using transistors, im pretty sure.

author: Zero999
author_rank: Super Contributor
timestamp: May 10, 2021, 01:35:20 pm
content: Quote from: Capernicus on May 10, 2021, 01:22:18 pmHow? Please post a schematic.

author: David Hess
author_rank: Super Contributor
timestamp: May 11, 2021, 12:30:04 am
content: What you are asking for is relatively easy to do if you accept some voltage drop. A current shunt is added in series with each output, or more likely ground in this case, and an operational amplifier is used to drive the second pass element to force the current from one output to equal the other output. This configuration is used to force current sharing when linear regulators are used in parallel.

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: May 12, 2021, 06:20:51 am
content: seems like LT4353 is right solution, but its bit expensive with all external component cost.

author: Zero999
author_rank: Super Contributor
timestamp: May 12, 2021, 08:15:51 am
content: If you want cheap, then why not use the classic discrete ideal diode circuit? It requires P-MOSFETs though, which are more expensive, given the same voltage drop. For the circuit to work well, the BJTs need to be matched, ideally with a simiilar hFEand more importantly the same VBE. Fortunately it's possible to buy BJTs in matched pairs, ICs containing two BJTS on the same bit of silicon, so they have the same characteristics. The thread linked below recommends the DMMT5401, which isn't expensive.https://electronics.stackexchange.com/questions/223935/understanding-an-ideal-diode-made-from-a-p-channel-mosfet-and-pnp-transistors
Parallel USB ESD protection - Page 1
Forum section: electronics / beginners

author: kristakis
author_rank: Contributor
timestamp: June 28, 2024, 02:19:42 am
content: I'm using a SRV05-4 for USB 2.0 ESD protection and it has 4 I/O ports/pins. I only need 2 for the USB port and rather than leaving the other 2 unused, is there any problem with putting them in parallel? As I see it, if something goes wrong and diodes start conducting, won't having an extra path to share the load be helpful?Here's the datasheet:https://www.onsemi.com/pdf/datasheet/srv05-4-d.pdf, I'm using Option 2 in the Applications Information (page 5) with a 10K resistor.

author: wraper
author_rank: Unknown
timestamp: June 28, 2024, 02:31:29 am
content: If it's full or low speed USB, there is no problem with parallel connection. However I'd simply use another device like USBLC6-2SC6, SRV05-4 is very expensive for what it is and redundant for the task.
parallel windings +  4 diode rectifier vs. series windings + 2 diode rectifier - Page 1
Forum section: electronics / beginners

author: ledtester
author_rank: Super Contributor
timestamp: June 15, 2018, 03:54:51 pm
content: In this video at the 1:57 mark the narrator says he converted the two halves of a center-tapped transformer winding into parallel windings for use with a full bridge rectifier:My question is would there be any significant difference between doing that and just using a two diode full wave (non-bridge) rectifier leaving the windings in series?The configurations being compared are shown in this document:http://www.hammondmfg.com/pdf/5c007.pdfas "FULL WAVE Capacitor Input Load" and "FULL WAVE BRIDGE Capacitor Input Load".The formulas on that page suggest that peak DC voltage remains the same, but that the "I D.C." will be about 20% more for the full wave bridge configuration -- assuming that parallalizing the windings will double your current capacity. Is that right? Are there any other factors to consider?

author: Benta
author_rank: Super Contributor
timestamp: June 15, 2018, 04:08:25 pm
content: It's all about winding resistance, which correlates with core aperture.For a center-tapped, two rectifier layout, only one half of the secondary is supplying current at any time, which is inefficient.With the parallel secondary, bridge rectifier layout, the secondary is utilized fully. You'll have one extra diode voltage drop, which is only an issue at low secondary voltages.My feeling is, that the 20% figure is a bit optimistic, my estimation would go towards 25%, but this is very dependent on transformer size.

author: Kevin.D
author_rank: Frequent Contributor
timestamp: June 15, 2018, 07:17:23 pm
content: Higher utilization of the transformer V.A rating with a full bridge rectifierthan with a full wave rectifier.look at the two configurations below (capacitive filter)FullBridge we can get 1.41*0.62 = 0.874 of the transformers V.A ratingFullWave we only get 0.71*1.0 = 0.71 of the V.A ratingSo ~ 16% better utilization.As Benta posted a fullwave is only using 1/2 of the transformer winding on each half cycle whilsta fullbridge is utilizing the whole winding on each half cycle.At lower secondary voltages though the extra 2 diode voltage drops of the fullbridge rectifier will constitute a greater portion of the available output power so at this point a fullwave becomes relatively more efficient.regards.
paralleled Buffer Outputs - Current Share Resistors necessary? - Page 1
Forum section: electronics / beginners

author: Andree Henkel
author_rank: Regular Contributor
timestamp: January 17, 2025, 03:56:41 pm
content: Hallo, I use a double Buffer 74LVC2G17 to boost current drive capability of a clock I generate with a LTC6905.Question is, do I need resistors at the outputs of the single buffers, bevore combining them. And if so, what are reasonable values?So far I skipped them and got no problems, but I´m not sure if this is a clean solution. My worry is, the delays and rise / fall times although same die and length matched layout may slightly differ so I basically get short time "bus contestion" situations at switching where one buffer sources current into the output of the other.

author: tggzzz
author_rank: Super Contributor
timestamp: January 17, 2025, 05:46:52 pm
content: Quote from: Andree Henkel on January 17, 2025, 03:56:41 pmMore of a problem: highdi/dtinducing voltages in Vcc/Gnd leads, and transmission lines/loads on the board.

author: CaptDon
author_rank: Super Contributor
timestamp: January 17, 2025, 07:49:50 pm
content: Just make sure to have some good bypass capacitors on the supply rails right at the buffer package. We have done some very unacceptable things like stacking 74LS245 etc. on top of each other or paralleling all the inputs to a buffer as well as all of the outputs to directly drive 5VDC relay coils or even incandescent panel lamps. Sometimes you 'just have to do what you have to do' when a test fixture for a one off product needs to be built overnight! Anyway, you should be fine, the delay mis-match at most would be expected to be under 1 nanosecond. Anyone remember seeing as many as 4 2102 ram chips soldered on top of each other with the chip select pins bent out and hardwired? Those were the days, turning a 4K X8 into a 16K X8 or sometimes just an 8K X8. Fun times!!

author: tggzzz
author_rank: Super Contributor
timestamp: January 17, 2025, 08:11:02 pm
content: Quote from: CaptDon on January 17, 2025, 07:49:50 pmYup, I remember those.Nowadays it is done in-chip; look at flash memory chips' cross sectionBut be careful with 74LVC1G devices. I have three of those with 143ohm series resistors driving 2.5V into a 50ohm transition line with a <300ps transition time.

author: Andree Henkel
author_rank: Regular Contributor
timestamp: January 20, 2025, 11:31:39 am
content: Thank you all.I´ll look to provide proper decoupling.My layout will be very compact, so the round trip delay at buffer output to load will be lower than the rise/fall times.
Parameters for PCB material selection for high speed ? - Page 1
Forum section: electronics / beginners

author: muthukural001
author_rank: Regular Contributor
timestamp: June 20, 2019, 02:38:37 pm
content: Hi,I have a job that I need to compare the different PCB materials that suit better for our high-speed design such as PCI gen 4 and 10Gbps serdes...I am wondering about the parameters that are specific to high-speed design...I know Dk and Df are basics...What else other than these?Thanks,Muthu

author: gar8814
author_rank: Newbie
timestamp: July 25, 2020, 02:52:19 am
content: Hi am using Megtron6 from Panasonic for a board that has signals that run at 10Gbps. We chose this predominately for the Dk Df values. One thing to note that boards made with this class of material do not do well when reworking with the soldering iron, so make sure you don't plan to make much component changes after initial assembly.Cheers

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: July 25, 2020, 07:03:08 am
content: You have higher-quality FR4-ish materials (like FR408HR) which will probably be fine up to 10 Gbps if you don't need to have very long traces.If you do need higher performance, Megtron6/7 is common, though a issue with Megtron is that (or at least so I'm told by a number of PCB houses) the prepregs have a short shelf-life, so very few houses will stock a lot of it, and usually require custom order and high minimum-order-quantity. Isola has a family of substrates called I-Tera, which is very similar in performance to Megtron, but most PCB manufacturers seem to prefer it for prototyping/low volume.As for specific parameters: Something that can be important is the weave of your material, especially if you get thin trace widths. Many PCB substrates (in fact, all the ones I listed here) are built by using a glass fiber cloth that is then kinda coated in a polymer. The glass fibers have a different dielectric constant than the polymer, so depending on if your traces are above a line of weave or not you can see a different impedance. (image source:https://blog.lamsimenterprises.com/2011/01/08/fiber-weave-effect-timing-skew/)There are a few ways around this - one is to put your traces at an angle to the weave. This way you can never have a trace that is completely above or next to a glass weave for extended lengths, minimizing the impact.Another is using cloth types that are spread out (eg 1086 is better than 1080 which is better than 106). Most manufacturers will provide lists of what cloth is used in what substrate thickness, so you can use this to help make your selection.The end-all solution to these issues is to go to more homogeneous substrates like some of Rogers' materials, but that also comes with a higher price tag (and Rogers tends to not offer quite as thin dielectrics, which may or may not be an issue for you).
Parasitic capacitance - Page 1
Forum section: electronics / beginners

author: elki
author_rank: Regular Contributor
timestamp: March 08, 2024, 06:12:31 pm
content: I need to use a variable resistor, for which I was initially considering to use a digital pot in my analog circuit. However, it’s parasitic capacitance makes its use impossible in my high frequency applications (above 100MHz). Next, I looked at digital switches, which have a similar limitation. Is there any alternative to using manual pots and switches in order to still allow its digital control? Does anyone know how big parasitic capacitance is in manual switches (if any)? From testing manual pots, the capacitance seems to be negligible.

author: MasterT
author_rank: Frequent Contributor
timestamp: March 08, 2024, 06:29:07 pm
content: Alternative is P-i-N diode, extesively used in TV bands switching

author: ejeffrey
author_rank: Super Contributor
timestamp: March 08, 2024, 06:37:28 pm
content: There are digital step attenuators and analog or digitally programmable PGA/VGAs that will do this, even up to much higher frequency.

author: Jwillis
author_rank: Super Contributor
timestamp: March 08, 2024, 07:07:25 pm
content: You can increase the bandwidth of digital potentiometers by lowering circuit impedance with parallel resistors.Increase the Bandwidth

author: elki
author_rank: Regular Contributor
timestamp: March 08, 2024, 09:46:49 pm
content: Thanks. Are there any through-hole PIN diodes with the lowest possible parasitic capacitance?Quote from: MasterT on March 08, 2024, 06:29:07 pm

author: MasterT
author_rank: Frequent Contributor
timestamp: March 08, 2024, 09:57:16 pm
content: Quote from: elki on March 08, 2024, 09:46:49 pm

author: Terry Bites
author_rank: Super Contributor
timestamp: March 09, 2024, 09:21:06 am
content: As already suggested, a wideband VGA PGA is probably the best way to go, eg LMH6881An analog mutiplier could also work here. eg ADL5391PIN diodes have a log response and horrible tempcos which may be unsuitable for your needs.
Parasitic magnetic coupling "induces a certain voltage" across a trace? - Page 1
Forum section: electronics / beginners

author: incf
author_rank: Frequent Contributor
timestamp: April 01, 2025, 07:16:37 pm
content: This came up in another thread.Suppose a PCB has a 5V power supply rail. And it makes one "loop" near or around a trace carrying a 10A 100kHz signal (part of a SMPS).One commenter said something like  "the alternating magnetic field will induce a current in the trace carrying the 5V rail" and another corrected that remark by saying something to the effect that "it will induce a fixed/predetermined voltage across the loop/trace and the current will be whatever circuit impedance limits it to"Question 1: is this true for parasitic/air core transformers "that they really are ideal transformers" in that they don't saturate or appear to have the transformer equivalent of ESR.ie. that the amount of energy being coupled/the induced current is limited purely by the impedance of loop.Question 2: Is it possible to estimate the (order of magnitude) amount of EMF induced by a 10A 100kHz trace into a 1 turn loop accidentally formed on a 1.6mm thick PCB? While I vaguely remember some equations I lack intuition.I imagine it's probably only microvolts.Any trace that crosses at a right angle with a high current trace seems like it may be subject to some amount of magnetic coupling. Even on a 4 layer PCB where the middle two layers are ground and the high current trace is on the top, and the signal trace on the bottom.edit:  original quotes:Quote from: TimFox on April 01, 2025, 01:46:03 pm
Parasitic PCB! - Page 1
Forum section: electronics / beginners

author: johnnyfp
author_rank: Frequent Contributor
timestamp: June 14, 2013, 12:12:00 am
content: What does this statement mean from description of aMCP1402.QuoteIE what is a Parasitic PCB Layout?

author: c4757p
author_rank: Super Contributor
timestamp: June 14, 2013, 12:14:52 am
content: It means someone at Microchip was sleepy. It should be "the parasiticsinthe PCB layout" (parasitic capacitance/inductance).

author: johnnyfp
author_rank: Frequent Contributor
timestamp: June 14, 2013, 12:17:19 am
content: Cool I thought that the Parasites where taking over and infecting PCB's

author: c4757p
author_rank: Super Contributor
timestamp: June 14, 2013, 12:21:50 am
content: That is also a distinct possibility.
Parralel printer display / spy - Page 1
Forum section: electronics / beginners

author: JWoodrell
author_rank: Contributor
timestamp: February 11, 2015, 04:20:26 pm
content: Hey guys we have an old piece of equipment that prints status pages over a parralel port connection. Most of what it prints is useless and sometimes it just prints garble. So i was wondering if anyone had seen a project or sonething where the parralel output was taken to a screen so you could just see the output visually rather than burning paper.The parralel port protocol doesnt seem complicated so i may have to make this thing from scratch, but i figured i would ask if anyone had seen something like this as maybe a starting point.Thanks guys

author: Rigby
author_rank: Super Contributor
timestamp: February 11, 2015, 05:48:59 pm
content: LPT ports are bi-directional, so you should be able to find a USB->Parallel cable and (if the cable supports it) capture the output from that old device via a COM port on Windows, for example.If you have an old Linux box with a parallel port laying around you can probably just do something liketail -f /dev/parport0 | tee > printer.txtto get what you need.Older devices are usually ASCII only and their output is basically a streaming text file. The same characters used to control the printer such as Line Feed, Form Feed, Carriage Return and the like are just ASCII characters that text editors render as whitespace (or as newlines, carriage returns, etc.)
Part id - Page 1
Forum section: electronics / beginners

author: ColinA
author_rank: Contributor
timestamp: January 29, 2011, 09:14:13 pm
content: I have a ns dip8 markedM8942WP90067L2Does anyone have any info on it? I think it's close to a LM386N-1

author: Simon
author_rank: Unknown
timestamp: January 30, 2011, 08:14:02 am
content: what did it come out of ? have you tried googling the numbers, I found some weird labelled parts in a Russian piece of kit only to google the number and find it was a 7400 equivalent
Part Identification - Page 1
Forum section: electronics / beginners

author: Steve Wayne
author_rank: Contributor
timestamp: June 16, 2016, 10:17:18 pm
content: Help in identifying this part would be greatly appreciated. I found this part in a box of diodes I inherited. Its internal contacts are separated by about 300-400 µm. I assume it’s somehow I, V, or R controlled. If so, how do you test for its properties? Thanks.

author: wraper
author_rank: Unknown
timestamp: June 16, 2016, 10:19:23 pm
content: It's a reed switch.

author: Steve Wayne
author_rank: Contributor
timestamp: June 16, 2016, 10:45:10 pm
content: Thanks wraper. How do you test for its properties?

author: tautech
author_rank: Super Contributor
timestamp: June 16, 2016, 10:48:50 pm
content: Quote from: Steve Wayne on June 16, 2016, 10:45:10 pmMagnet

author: wraper
author_rank: Unknown
timestamp: June 16, 2016, 11:11:32 pm
content: Quote from: Steve Wayne on June 16, 2016, 10:45:10 pmgoogle what it is

author: JoeN
author_rank: Frequent Contributor
timestamp: June 17, 2016, 02:28:26 am
content: It's meant to be a magnetically operated switch. I guess the properties you can test would be leakage when open (should be so small it makes it almost impossible to test) and resistance when closed with a magnet plus tempco on that resistance. In general, I can't see tempco ever being much of a problem. Reed switches are rated for current but you will have to guess what will be safe from the closed resistance since it isn't marked.Found this:https://www.digikey.com/Web%20Export/Supplier%20Content/Meder_374/PDF/MEDER_Parameters_of_Reed_Switch.pdf

author: Steve Wayne
author_rank: Contributor
timestamp: June 17, 2016, 04:17:54 am
content: Thank you JoeN, ebclr & everyone. Excellent information.
Part Identification: AN 1149 transistor - Page 1
Forum section: electronics / beginners

author: hyteqsolutions
author_rank: Newbie
timestamp: May 13, 2015, 07:31:32 am
content: Good Evening All,HyTeQ-Solutions here. Been in business dealing with all manner of electronic repairs for a fairly long time now, but on this one part I am stumped.The code on the damnable thing reads: AN 1149 IRF4N65I have searched high and low for a replacement part or even a data sheet, the best I could do so far is this:http://www.globalsemi-group.com/list/?193_1.htmlNow, if that is correct and it's a TO-220F, I need to find a replacement and the only two store's within driving distance are: RS Components & Jaycar Australia!So, here I am, begging for help, I need to find something suitable that will work in circuit.Details of the circuit: T3.15a in w/ 250v AC and 12v DC out to recharge cordless drill.Hope that info helps.Thank You,- HyTeQ-Solutions.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 13, 2015, 08:09:34 am
content: More details about the circuit? Is this the main power switch in a flyback SMPS then? Power rating? Voltage input range? Controller chip (if any)?4N65 sounds reasonably like a MOSFET number, so I wouldn't be afraid of throwing any generic part of similar ratings in its place.Tim

author: android
author_rank: Regular Contributor
timestamp: May 13, 2015, 08:18:41 am
content: 1149 looks like a date code (week 49 of 2011). The part is probably a 4N65 power MOSFET. UTC made one:http://www.utc-ic.com/uploadfile/2012/0313/20120313104252109.pdfYou may be able to do a parametric search for a substitute using those specs.
Part identification help - Page 1
Forum section: electronics / beginners

author: Lani
author_rank: Newbie
timestamp: December 13, 2019, 11:30:48 am
content: Hi there everyone.... Got a reel of these and I tried looking all over the place for a data sheet or even a picture of one. It looks like a accelerometer/gyro type thingy.... Hard to use these when I have no clue what they are. If anyone can shed some light that would be fantastic. Have a good one all.-TimEdit - ANother question.... I'm pretty sure it's an accelerometer so are the pin outs for these pretty universal like op amps and such? I have over 1000 of these so I guess I could just try it out and see what happens.
Part identification?  - Page 1
Forum section: electronics / beginners

author: hneve
author_rank: Regular Contributor
timestamp: May 23, 2016, 04:27:50 pm
content: Anyone know what the bottom part in this picture is?Sent fra min D6503 via Tapatalk

author: jitter
author_rank: Frequent Contributor
timestamp: May 23, 2016, 04:30:00 pm
content: Probably an axial ceramic capacitor.
Part Identifying  - Page 1
Forum section: electronics / beginners

author: chris1971
author_rank: Newbie
timestamp: October 04, 2022, 05:46:51 pm
content: Hi all hope someone can help I trying to repair this board it is for a hot water heater that operates on lpg the part iam trying to identify is the black plastic component it generates the spark that a ignition cable attached to board via a 2.8mm spade there is no spark coming from unit

author: Buriedcode
author_rank: Super Contributor
timestamp: October 05, 2022, 03:15:39 am
content: That'll be the ignition transformer, potted to prevent arcing between winding layers.These generally aren't "off the shelf", and perhaps the best source would be another heater board. The few I've seen all have these transformers, but have different footprints, so I'm unaware of any standards here.

author: chris1971
author_rank: Newbie
timestamp: October 05, 2022, 02:59:35 pm
content: Thank you I've spent hours looking for this part will look for a old board
Part name - Page 1
Forum section: electronics / beginners

author: ebb2409
author_rank: Newbie
timestamp: June 29, 2025, 09:44:16 am
content: Hello! Does anybody know the part name of the connectors used in oscilloscopes for calibrating the probes? I need to buy some of them for a project. I have already searched in several electronics providers and here, but couldn't find it. Thanks!

author: BennoG
author_rank: Frequent Contributor
timestamp: June 29, 2025, 09:58:49 am
content: bnc connector

author: Sorama
author_rank: Frequent Contributor
timestamp: June 29, 2025, 10:03:10 am
content: Quote from: BennoG on June 29, 2025, 09:58:49 amHé probably means the square bracket.

author: jpanhalt
author_rank: Super Contributor
timestamp: June 29, 2025, 10:13:08 am
content: The search term is probably "test points." Keystone is one place to look (https://www.keyelco.com). Digikey and Mouser carry its parts.

author: coromonadalix
author_rank: Super Contributor
timestamp: June 30, 2025, 06:37:31 pm
content: like this ?HHC-183 Flat Terminal Positioning Insert with Dual Hole Design

author: NE666
author_rank: Frequent Contributor
timestamp: June 30, 2025, 06:58:30 pm
content: Quote from: jpanhalt on June 29, 2025, 10:13:08 amThanks, I've been looking for something like this (test/compensation loops). They do some nice surface mount versions, which Digikey carry as stock items.

author: jpanhalt
author_rank: Super Contributor
timestamp: June 30, 2025, 07:57:37 pm
content: Years ago, I discovered Keystone to find what I needed. Then once I have that, you can find it at a distributor.Two other "what's it called" sites are:Unusual connectors (mostly automotive and similar contacts) Del City: (https://www.delcity.net/store/)Omega for TC parts, which now seems to be here: (https://www.dwyeromega.com/en-us/)China site: (https://www.omegaengineering.cn/pptst_eng/OST.htm)

author: tooki
author_rank: Super Contributor
timestamp: June 30, 2025, 08:57:30 pm
content: Quote from: coromonadalix on June 30, 2025, 06:37:31 pmThat looks for all the world like some kind of Faston accessory (adapter?), not a probe loop. The distance from hole to edge is much too large.
Part number / serires of standard "servo" crimp connectors - Page 1
Forum section: electronics / beginners

author: Isamun
author_rank: Regular Contributor
timestamp: June 19, 2015, 07:04:39 pm
content: So.. This is obviously a newbie question that has been answered before.I've been searching high and low on the "professional" sites (ie. digikey, mouser, farnell..etc) for a servo crimp connector. I've seen a lot of Molex C-Grid C and others that's not the same series.Servo connectors in my book fits into a Futaba og JR style housing with the little retainer on the housing side (not the connector side) eg:Anyone know what product series these belong to?
Part replacement working - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: March 17, 2025, 02:03:01 pm
content: There's this IC - (https://www.ti.com/lit/ds/symlink/iso1452.pdf?ts=1742185199683&ref_url=https%253A%252F%252Fwww.mouser.in%252F) instead of this (https://www.nve.com/Downloads/il4685.pdf).TI is in PCB but footprint is designed for NVE part.If I just disconnect the signals coming to pin 7 and pin 10 in the TI part PCB, will it work fine?

author: BillyO
author_rank: Super Contributor
timestamp: March 17, 2025, 03:24:24 pm
content: No.First, something on the board might be relying on pin 10 if the board is designed for the NVE part.Second, pins 11-14 do not match up.

author: Freshman
author_rank: Regular Contributor
timestamp: March 17, 2025, 05:49:55 pm
content: Thanks for pointing that out.Also with the IL4822 part, Can you confirm whether it is required to put pull-up on pin 11 and 12 (1k) and pull down pin 13 and 14 (1k) ? What happens if I install or not? There is not mention of what to place on these pins in the datasheet.

author: BillyO
author_rank: Super Contributor
timestamp: March 17, 2025, 07:11:39 pm
content: Pull-ups and pull-downs are not required. Certain busses may require termination resistors. See figure 26 on page 19.

author: Freshman
author_rank: Regular Contributor
timestamp: March 18, 2025, 02:26:14 am
content: I have added 1k pull-up resistor on pins 11 and 12. 1k Pull down on 13 and 14. Would it cause any issues

author: BillyO
author_rank: Super Contributor
timestamp: March 18, 2025, 02:30:49 am
content: Well, at this point you are in uncharted territory. I can only think doing so will degrade the signals.Why did you do that when the spec sheet does not call for it?

author: wraper
author_rank: Unknown
timestamp: March 18, 2025, 02:42:40 am
content: QuoteFirst of all, you don't need to disconnect anything as those NC pins are not internally connected in the IC. Secondly, original part has built in isolated DC/DC converter, TI part does not. NVS part has Vin on one side (VDD1A) and Vout (VDD2) on another, TI part has Vin (Vcc1/Vcc2) on both sides. Unless converter was left unused (very unlikely, why would anyone use such part without utilizing it), you need to add some isolated DC/DC converter module to the circuit to use TI part.

author: Freshman
author_rank: Regular Contributor
timestamp: March 18, 2025, 05:02:29 am
content: Since the pins will not have a stable state when idle, I thought of adding the pull-resistors to give a default state. If I reduce the resistor value from 1k to say 0.68k, would it make it better?
Part substitution - Page 1
Forum section: electronics / beginners

author: boshepard69
author_rank: Newbie
timestamp: January 08, 2020, 04:13:03 am
content: Hi everyone! I'm new to the forum but I've been following it for a while. I have a question for all of you knowledgeable folks out there. I have been troubleshooting and repairing a lot of our Cisco power supplies that have went out and I have a few that are a different model that have bad Mosfets part number IXFH12N50. I am having a hard time finding them and would like your help finding a suitable replacement. I can troubleshoot and repair, but when it gets into needing to replace a part like this with a different model, I want to make sure I'm choosing the right thing. It's a To-247 case. I appreciate any help you can give me!

author: CRCLARKE
author_rank: Contributor
timestamp: January 08, 2020, 05:21:49 am
content: check this outlll\/

author: boshepard69
author_rank: Newbie
timestamp: January 08, 2020, 05:25:30 am
content: Thanks!!!!!
Part type? Replacement? - Page 1
Forum section: electronics / beginners

author: Crambone
author_rank: Frequent Contributor
timestamp: February 19, 2024, 09:26:40 pm
content: This shows an open and I’m not sure what it is any help if it should show an open if not what to use to replace it?

author: selcuk
author_rank: Frequent Contributor
timestamp: February 19, 2024, 09:44:14 pm
content: 200 ohm resistor.https://www.bourns.com/data/global/pdfs/PWR221T-30.pdf

author: Crambone
author_rank: Frequent Contributor
timestamp: February 19, 2024, 10:07:14 pm
content: Thank you!
Partial charge of hybrid capacitors - Page 1
Forum section: electronics / beginners

author: raff5184
author_rank: Regular Contributor
timestamp: March 12, 2021, 04:25:13 pm
content: Hi,how can I calculate/measure a partial charge (for example 50%, 80%) of a hybrid energy storage capacitor? How do I know when the capacitor is at its, say 80%? I'm using these Vishayhttps://www.vishay.com/docs/28409/196hvc.pdfI am not sure because (1) being hybrid caps, the voltage doesn't start from 0, so I don't know if the behavior is the same of a normal capacitor; (2) during discharge I could use the time constant t=RC, but my load is not a resistor but an entire circuit, so would it make sense to use its "equivalent" R, as R=V/I? (3) I don't know what indicates the charge during the charge phase