hybridfree/eevblog-posts huggingface dataset:
VFD connected to Single Phase Induction Motor - Page 1
Forum section: electronics / beginners

author: made2hack
author_rank: Frequent Contributor
timestamp: February 27, 2019, 11:36:31 am
content: Hi all,I've got this induction motor which I've mentioned in a previous post:Electric Motor SpecsThe motor has 4 connection points, U1, U2 and Z1 and Z2. U1 & U2 are the primary coil (approx 5 Ohm) and Z1 & Z2 is the secondary coil (approx 10 Ohm).There is also a start capacitor of 20uF to get it started.I want to connect it to a VFD. The VFD I have is your typical chinesium AT1/AT2 model with Single Phase In (ie 220V) and either Single Phase Output or 3 Phase Output. The output terminals are U, V, W. As per the instructions, they say to connect W and V terminals across the main coil (so U1 & U2 on my motor). And they say connect secondary coil after removed capacitor to U. So I assume to connect U to one end of either Z1 / Z2. The other end is left floating.I cannot get the motor to start under it's own power. The VFD throws error 6 (over current). I can get it to start and work by manually twisting the motor shaft until it starts working under it's own power and then the VFD works as expected (adjust speed / frequency, fwd, reverse etc).I am assuming I still need to connect the starting Capacitor but I'm not sure over which terminals to connect it to or how it would work together with the VFD.Any thoughts?Thanks,

author: Wolfram
author_rank: Frequent Contributor
timestamp: February 27, 2019, 11:47:56 am
content: The motor will not be able to start if one end of the start winding is left floating. Connect the other end of the starter winding to the corresponding end of the run winding, as you would when using it as a capacitor-run motor.

author: made2hack
author_rank: Frequent Contributor
timestamp: February 27, 2019, 11:59:06 am
content: Is the start winding the higher ohm one ? Ie Z1 / Z2?

author: made2hack
author_rank: Frequent Contributor
timestamp: February 27, 2019, 12:18:49 pm
content: Ok, so I got it to work by connecting one end of Z (start winding? The one with higher resistance) to one end of the running winding. It starts fine but it goes into Overcurrent at around 3.3 - 4 Amps. Before, it would be running at 1.8 Amps full speed (when only one winding was connected). Now, it cuts out not quite full power. The VFD is purported to be a 1.5KW VFD with a rated current of 8A.
VFD Display Driver & STM32 Nucleo Board - Page 1
Forum section: electronics / beginners

author: riacob
author_rank: Newbie
timestamp: June 04, 2022, 09:19:20 pm
content: Hello everyone,I have recovered, from an old DVD reader, a VFD display and it's driver. The chip is a "CS16312", which appears to be a clone of NEC's "PD16312".Actually, the whole DVD players seems a clone of a philips one...Anyway, I've found myself with the "Semico" (clone) datasheet at hand, which is totally in chinese, and later found the NEC datasheet (in proper english of course).The problem is, i tried interfacing to it using an STM32 with the SPI interface, but it does not seem to give any signs of life.My issues right now are:1- I'm not sure if the devices interface in the same way, sadly I don't have a DSO or signal analyzer to compare my STM32 SPI output to the data coming from the "original" main board;2- I'm not sure if I'm interpreting the datasheet right (so i might be doing something wrong);3- I'm not sure if I somehow fried the chip, because it was originally working;4- I don't think I accurately understood the way to use the "fixed address" and "incremental address" modes;What I've currently extrapolated (what I'm doing) from the NEC datasheet1- The byte order is LSB-first;2- CPOL is 1 and CPHA is 2;I'll attach the two datasheets, if anyone knows techical language in Chinese, your help would be much appreciated in comparing the two.Sorry for any mistakes but I'm a newbie to electonics and a non-native English speaker.Thanks in advance to everyone who'll help me.EDIT:I just bought myself a basic logic analyzer, which should arrive tomorrow.Also, currently I'm doing the SPI operations in the following order:1- Set display mode2- Set data3- Set address & send data4- Set controlIn "fixed address" mode

author: m k
author_rank: Super Contributor
timestamp: June 13, 2022, 07:57:40 pm
content: What was the situation when it worked, before or after you did something?NEC sheet 14 has close ups.Put data available when CLK goes down, then when CLK rises the chip takes the data in.Same with data out, when CLK rises the data is available, and old data is gone.
VFD Display - Protocol inquiry - Page 1
Forum section: electronics / beginners

author: StEeLz
author_rank: Newbie
timestamp: June 15, 2015, 06:46:17 pm
content: Hi EEV Community!After seeing Dave hacking a VFD display on the episode #717, I've decided to salvage one as well (so beautiful/vintage).I found that the Buick LeSabre instrument cluster had one, and the good part with this car is the VFD is a module, it is not directly attached to the mainboard. The 16 x 2 (5x7 pixels each) module has a driver integrated.The 2 ICs on that module are Delco parts, undocumented of course. Seems like a driver and a memory/shift register.I have now figured out all the pins, but I am struggling with the kind of protocol used. I would like to use an Arduino/Raspberry Pi to send messages on it.3 Pins are active, I have done some screenshots.Is it I2C? SPI? Serial? or proprietary?This is the pattern repeated (31.8 Hz)The sequences starts with 2 bits, then 32 bits :When doing a closeup on the first 2 bits, it looks like this (Signal #1 : Zooming made some peaks disappear, but what is this middle signal, not square wave?). Clock seems to run around 500KHz:If you ever saw that or have any clue...I already appreciate if you read until here! Have a great dayBaptiste
VFD help - Page 1
Forum section: electronics / beginners

author: Chipset
author_rank: Contributor
timestamp: June 16, 2012, 08:16:14 am
content: So I pulled this VFD from a microwave oven some time ago, I really wanna use it for a project as a panel meter but I know fuck all about VFD's.Here are some pictures,As you can see it's an NEC display with a part number of FIP4J9A, however googling that just gets me a FIP selection document which details picking a FIP display for a product.Looking through that document it appears my display is a semi-custom model, but I'm not sure.All I really need to know is how to make it work, the back of it has a handy wiring schematic and from that and the document it's pretty apparent that this display needs to be multiplexed, which I would love some info on how to do.I might point out that in the original board I took it from, it was wired directly into the pins of a giant 40 pin micro. Sadly I didn't keep the board.Any info is appreciated, step by step instructions and a schematic even more so.Thanks in advance.

author: Psi
author_rank: Super Contributor
timestamp: June 16, 2012, 08:36:59 am
content: I don't know much about VFDs either but i got one to light up some segments once.First you need to find the filament wires. (Those 3 thin horizontal wires you can see on the picture).Connect them up to a current limited powersupply and start low.Bring the current up slowly until (with the room lighting off) you see them start to glow a tiny bit.Quickly reduce the current until they completely stop glowing.*Be careful* if you use too much current they will glow bright red and melt, then it will be useless.Get a second power supply and common it with the first powersupply.Start at 5v and connect it to various pins. You should see segments light up. If not try 12v, then 24 etc.It should definitely light up at 24V

author: Bored@Work
author_rank: Super Contributor
timestamp: June 16, 2012, 08:38:45 am
content: Start with reading the wikipedia article about VFDs. It roughly explains how they work and has some pointers to more information.

author: amyk
author_rank: Super Contributor
timestamp: June 16, 2012, 12:06:51 pm
content: If the FIP selection document you found was this:http://www.excesssolutions.com/mas_assets/acrobat/ES1672.pdfThen the last 2 pages give a good guide on how to use them.The FIP4Q8A looks the most similar to yours. That model requires only 2.4VAC filament voltage and 81mA.The two outermost pins are for the filament. The "schematic" on the back is actually the conductive traces to the anodes.

author: codeboy2k
author_rank: Super Contributor
timestamp: June 17, 2012, 03:11:55 am
content: Quote from: Psi on June 16, 2012, 08:36:59 amI did thatonly onceThere's some good information here on the Noritake websitehttp://www.noritake-itron.com/subpages/applicnotese/vfdoperapn.htm
VFD inrush current - Page 1
Forum section: electronics / beginners

author: xoom
author_rank: Regular Contributor
timestamp: May 18, 2017, 01:41:23 pm
content: Hi, have to fix VFD007L21E. Found that inrush current limiting resistor is almost burned.. when meassuring it shows ~900ohm. And by size its like 2W resistor.. Why its burned and what better nominal to put? btw there is relay across it so its active control.. after caps are charged it should short out that resistos.. tested that relay and its working..

author: jmelson
author_rank: Super Contributor
timestamp: May 18, 2017, 07:55:57 pm
content: OK, I assume this is a variable frequency drive (not vacuum fluorescent display).If it has a resistor to slow-charge the capacitor bank, and a relay to short the resistor before starting operation, then either the relay was not operating, or there is an excessive load on the DC side.These things usually have some kind of voltage sensing circuit that decides when to switch on the relay. If there is an unexpected load on the DC side, the cap bank voltage may never rise to the level where the relay turns on. That will smoke the resistor for sure. Possibly there is a shorted transistor in the inverter section.When you say you tested the relay, do you mean you tested it alone? Then the circuit that controls the relay may be bad, or as I say above, the caps may never charge to the required voltage.Jon

author: Paul Moir
author_rank: Frequent Contributor
timestamp: May 18, 2017, 10:38:12 pm
content: Happen to be repairing one right now that looks the same. One motor phase had a short and so the inrush resistor exploded (which was a little surprising!). The identical unit has a 120 ohm inrush limiter. I'll be trying out STGP10NC60KD to replace the original, obsolete Fuji Electric 1MB05D-060 IGBTs. This is the first time I've tried to match up an IGBT so it may not be successful.Can you post a pic so we can make sure we're working on the same thing?EDIT: I guess I can too. CR1 is where the resistor was.

author: jmelson
author_rank: Super Contributor
timestamp: May 19, 2017, 03:36:39 am
content: If the IGBTs popped, it likely took out the gate driver chip, too. From experience, I'd replace the driver for both transistors of that phase, and both transistors of the popped phase, too.Jon

author: Paul Moir
author_rank: Frequent Contributor
timestamp: May 19, 2017, 05:19:28 am
content: Yes, fortunately it's easily available: IR2112. Mine seem healthy but I ordered one anyway.EDIT: Just dropping a note that the repair was successful. The IR2112 turned out to be fine as did the other phases IGBTs. I also had to get some new 0.3mm insulating thermal pad covers for the to220 packages. My version is the Automation Direct GS1-10P5. I didn't realize how inexpensive the drive was before I ordered the parts. It certainly doesn't look that cheap on the inside: nice parts and nice workmanship. But probably not worth fixing (~$10/phase for IGBTs & driver + $5 for the silpads).
VFD Layout constraints have ground running through choke, no bueno? - Page 1
Forum section: electronics / beginners

author: codohundo
author_rank: Newbie
timestamp: April 21, 2023, 02:26:31 am
content: I'm building a box for a CNC Spindle VFD, in order to keep the 220v mains (split phase) lines as short and tidy as possible the Zero Phase Reactor (common mode choke) is really close to the VFD, and the Mains ground for the Drive ends up wanting to run straight through the middle of the toroid, is this inconsequential or should I route the ground awkwardly to avoid it? Any thoughts would be appreciated.
VFD, LED, and LCD update speeds... - Page 1
Forum section: electronics / beginners

author: alank2
author_rank: Super Contributor
timestamp: September 10, 2014, 01:42:26 pm
content: Hi Everyone,Well, I don't need to ask about LED's because they can switch so fast you can even see it, but I wonder about the update speed of VFD vs LCD. A LCD datasheet I read said something about a response time of 180ms for on and 100m for off, so taking the max there you can get about an update speed of 5 times per second. How fast are VFD's? I looked at a couple of datasheets, but didn't see the speed listed...Thanks,Alan

author: mariush
author_rank: Super Contributor
timestamp: September 10, 2014, 02:31:16 pm
content: With LCD, it's not the actual panel that's slow, it's the controller. Some can update very fast. The controller runs at slow frequencies and due to multiplexing pixels, update rate is slow.I don't have much experience with VFDs. May want to look at OLED displays, they may update faster.

author: bktemp
author_rank: Super Contributor
timestamp: September 10, 2014, 03:03:58 pm
content: You have to distinguish between update speed and response time.The update speed tells how fast you can write new data to it, like the samplerate of a DAC. The response time is more like the analogue bandwith of the system.LCDs have a update rate in the range of 60-200Hz. The response time is quite slow and has a strong temperature dependency. It can be as low as a few seconds for low temperatures but is typically in the range of 10ms for tft lcds and 100ms for passive lcds.Since OLED displays are scanned the same way as lcd screens their update rate is in the same range, but their response time is much faster, typically in the microsecond range.I have no real values for vfds, but they are quite fast. My guess is somewhere near oleds.

author: DanielS
author_rank: Frequent Contributor
timestamp: September 10, 2014, 05:31:46 pm
content: VFDs will turn on/off as fast as you can drive their voltage up/down, much like LEDs, neon bulbs or plasma displays.LCDs are so slow compared to emissive display technologies because molecules need to align with the electric field - there is an electromechanical process to their operation. Same goes for e-Ink except the mechanical part is even more acute.
VFD testing rig advise - Page 1
Forum section: electronics / beginners

author: JohnXJohn
author_rank: Newbie
timestamp: January 24, 2024, 05:26:22 pm
content: I'm thinking to build I fvd testing rig to learn and test troubleshooting, dealing with different wire lengths playing with oscilloscope etc. I've done plenty of general electrical work but not much electronics.General outline:3 hp 3ph motor belt drive to 4.25 hp pm dc motor wired to resistor bank.Id like be able to simulate various real world conditions like high starting loads, sudden loads etc..Current thought is to use a bank with high wattage low resistance 3 ohm or so and PWM the output current of the dc motor with an Arduino. Would that work same as a variable resistor?Cooling is an obvious issue, what else ?Thanks bunch!

author: Zero999
author_rank: Super Contributor
timestamp: January 26, 2024, 09:56:04 pm
content: A word of warning: use an oscilloscope with a high voltage differential probe. Never float your 'scope.You can also consider an isolation transformer. 3 single phase 1200VA transformers could be used to make a 3 phase transformer.Regarding PWM, yes sort of, but the frequency needs to be high enough not to result in torque ripple. You'll need a back-EMF diode, as it's possible the motor's inductance will damage the switching device. It will also help to smooth out the current through the motor and thus the torque. Consider an optically-isolated MOSFET driver.

author: JohnXJohn
author_rank: Newbie
timestamp: January 27, 2024, 01:58:13 pm
content: Quote from: Zero999 on January 26, 2024, 09:56:04 pmThank you!I already own 1300v rated diff probes, what would you consider high enough of a frequency?

author: Zero999
author_rank: Super Contributor
timestamp: January 28, 2024, 10:04:04 am
content: This isn't something I've done before, so I thought I'd briefly read up on it.VFDs don't work at that higher frequency so, you don't need a massive bandwidth.100MHz aught to be more than enough.Here's an interesting article I found on Tektronix website.https://www.tek.com/en/documents/primer/making-measurements-on-3-phase-motor-drives-with-an-oscilloscope
VFD to control 3 phase AC induction motor 400V 6000 rpm - Page 1
Forum section: electronics / beginners

author: dexterbot80
author_rank: Newbie
timestamp: March 21, 2019, 02:55:57 pm
content: Hello,I want to control the speed of a woodcutter that is equipped with an asynchronous three-phase motor 400V 6000 RPM 6KW.From the searches I came to the conclusion that a VFD would successfully solve my problem so I decided to build one.Arduino DDS Sinewave Generatorhttp://interface.khm.de/index.php/lab/interfaces-advanced/arduino-dds-sinewave-generator/seems to me the simplest solution for adjusting the frequency - I tested this circuit and obtained a three-phase sinusoidal signal.This is my control circuit:https://www.dropbox.com/s/5qbsr6hkr6mztf4/CONTROLL%20BOARD.png?dl=0This is my gate driver circuit:https://www.dropbox.com/s/oacyodtjh10pahm/GATE%20DRIVE.png?dl=0Please help me to better understand how the control circuit works and tell me if the electronic circuit is correct.Basically, I have to get 6 Hi / Lo signals that will command the three-phase IGBT bridge.Thank you

author: Zero999
author_rank: Super Contributor
timestamp: March 22, 2019, 10:41:42 am
content: I admit, I haven't checked out the links. It seems like you're reinventing the wheel.What not use an off the shelf inverter? Preferably one with a serial interface, allowing you to control it using an Arduino.

author: james_s
author_rank: Super Contributor
timestamp: March 23, 2019, 11:33:38 pm
content: Building stuff like this is fun, but if you just want to run your motor you can get an off the shelf VFD for a few hundred bucks, probably less if you're willing to gamble on a used one. These will offer far better performance and more features than you're going to get by building one.

author: jmelson
author_rank: Super Contributor
timestamp: March 24, 2019, 01:39:04 am
content: Assuming a 2-pole motor, you would need 100 Hz, which almost any VFD today will do. One issue is the motor may be a low-inductance motor, and may require some inductors between the VFD and motor. I run a 60,000 RPM air bearing spindle from a VFD that will only go up to 400 Hz, so that limits me to 24,000 RPM, but it works. I had to add inductors to each phase wire. But, it works.Designing a 400 V VFD is not for the beginner. You need to use purpose-designed FET/IGBT gate drivers, and even still, trace inductance and layout issues can cause expensive explosions.Jon
VFD with CDS maybe? - Page 1
Forum section: electronics / beginners

author: hermitengineer
author_rank: Regular Contributor
timestamp: June 25, 2022, 12:25:22 am
content: My microwave has a really dim VFD display. I decided to take a close look at it to see if there is anything easily fixable. I know VFDs leak, but this is only a few years old.Anyway, one thing I noticed on visual inspection is that there is a black spot on the front of the display in the lower right corner. It is also clouded around the right side. I noticed that there is a metal ring (or at least a half-ring) which is mounted at a diagonal to the front pane. It is connected to a wire strip on both sides which goes down to the rest of the internal contacts and there is a third strip that comes up between the other two. I can't see through the cloudy black part well enough to get more details than that. But I wonder, is this a light sensor intended to adjust the brightness? If so, being covered in a black cloud would definitely explain why it keeps the display so dim.Either way, is that black spot likely to indicate that the display itself is failing?

author: BrokenYugo
author_rank: Super Contributor
timestamp: June 25, 2022, 12:31:04 am
content: That's the "getter", a sort of vacuum pump to catch any errant molecules. You can tell the tube has lost vacuum if the spot turns white.https://en.m.wikipedia.org/wiki/Getter

author: hermitengineer
author_rank: Regular Contributor
timestamp: June 25, 2022, 03:22:19 am
content: Ok, so the black spot probably means it hasn't leaked yet then.Now, on schematics for VFD-based displays, I see that there are two sets of pins, labeled F1 and F2, that seem to be the filament power? On this one, F1 and F2 go directly to one of the secondary windings on the step-down transformer. The voltage between those two connections is 3.5VAC. Does that sound reasonable?The other secondary is 24V with a center tap. There is a 7915 regulator on the board for a -15V supply to something, probably display-related. One chosen reference, a plug with a black wire, shows voltages between -20 and -15V on various VFD pins. Not sure if this is a true ground yet though.
VGA LCD CRT MONITORS MODS - Page 1
Forum section: electronics / beginners

author: Klomderper
author_rank: Newbie
timestamp: March 29, 2015, 05:42:23 am
content: I have a generic VGA LCD monitor, I want to MOD it as to look like an old orange monochrome display from back in the day. How easy can this be done and would you mind making a video? I would also like to see other MODS of other VGA uses as well.

author: German_EE
author_rank: Super Contributor
timestamp: March 29, 2015, 07:55:35 am
content: You did not say what sort of video signal you wanted to feed in to your modified display. The easiest way to do this is to set your PC to output a black and white image using the video settings in the control panel.Now the modifications. With the red channel connected to the VGA plug and the blue channel disconnected insert a variable resistor in series with the green channel (470 ohm should be fine) and adjust to taste. Playing around with a paint program I got orange by using 100% red and 75% green (HTML ffbc00).

author: Klomderper
author_rank: Newbie
timestamp: March 29, 2015, 01:18:23 pm
content: Yes, you are correct, I did not specify, I would like to keep the VGA input functioning. My idea was to strip out the back lights and install RGB LED's.

author: Prime73
author_rank: Regular Contributor
timestamp: March 29, 2015, 01:42:08 pm
content: software emulator?try this:https://github.com/Swordfish90/cool-retro-term

author: German_EE
author_rank: Super Contributor
timestamp: March 29, 2015, 02:10:18 pm
content: Well, as you can see there is no need to strip out the backlight and install LEDs, just modify the VGA signal to display the colors you want using a series resistor in each lead. Just make sure that you send a black and white VGA signal from your PC.

author: Klomderper
author_rank: Newbie
timestamp: April 03, 2015, 05:15:19 pm
content: Love it! Thank you!
VHDL trying to read and write signed reals with textio - Page 1
Forum section: electronics / beginners

author: chris_leyson
author_rank: Super Contributor
timestamp: July 07, 2017, 08:47:35 pm
content: Hi guys this is driving me nuts. I'm using Xilinx ISIM and trying to read and writesignedreals using textio but it just doesn't want to work. Out of desperation I just cut and paste a test bench from herehttp://vhdlguru.blogspot.co.uk/2012/01/reading-and-writing-real-numbers-using.htmland that works but as soon as I put a + or - in front of any number in 1.txt ISIM says "at 0 ps: Error: Read a non-real, a real is expected". Am I missing a library or does textio only handle unsigned reals ?
VI vs Time battery curves to show remaining power left under the curves - Page 1
Forum section: electronics / beginners

author: ez24
author_rank: Super Contributor
timestamp: August 28, 2015, 07:56:52 pm
content: I asked this question on a very long post (somewhere around 62 pages) and found out that I linked in the YT wrong. Just FYI when you link in a video, it links in at the spot where you are watching (sometimes). So I linked in after my story and did not get any answers. So here is a new post with the correct link.I want to know is there any truth to the VI vs Time graph that he draws, ie is there power under the combined curves? I have a hard time believing he could be lying when he is starting a company and posting it on YT. I know people exaggerate but this ?I do see there are more thumbs down than up, and this is the first video I found like this.Well anyway the part I am interested in runs only a couple of minutesI have seen graphs where one vertical scale on one side and another is on the other side. He did not show that it should be on the right side.https://youtu.be/622uCZ_pE0w?t=496This is only about the curve not the Batterizer for more info about that see :https://www.eevblog.com/forum/blog/eevblog-751-how-to-debunk-a-product-%28the-batteriser%29/currently at 71 pagesSo PLEASE no discussion of the Batterizer, just the VI vs Time curves from the video. Is it right or wrong?thanks

author: Delta
author_rank: Super Contributor
timestamp: August 28, 2015, 09:23:25 pm
content: Wrong.

author: Chris C
author_rank: Frequent Contributor
timestamp: August 28, 2015, 10:07:23 pm
content: First, the graph is horrendously off scale, in an intentionally misleading way. He draws a vertical line in the middle, like this:|--|--|To represent where a battery would drop below nominal voltage and become useless. Had the graph been to scale, it would have been about here:|------------------------------------|--|Better yet, here's a REAL discharge curve under various constant current loads:There is very little usable energy left in the battery once voltage starts to drop below nominal, which it does rapidly.I have not looked at the Batterizer, but presumably, it uses a voltage boost circuit to provide nominal voltage (V) anyway. But if your device needs 100mA at V, and the battery is at 1/2 V, that means the Batterizer is going to be draining 200mA from the battery! And the battery voltage is going to drop off even faster than in the graph above.So that's the second error in the YT graph, claiming the current drain on the battery will remain constant, even when the battery voltage drops below nominal.
Via in pad - Page 1
Forum section: electronics / beginners

author: Veketti
author_rank: Regular Contributor
timestamp: April 02, 2023, 09:12:49 am
content: Dear All,Is it how big of a mistake to have via in pad if hand soldering components? I've tried to google and some say that it is bad in reflow process that the solder paste gets into the via and cause bad connection. Nothing I have found about hand soldering. I have found it very tempting at least in four layer PCB where inner layer is GND to put all 1206 size capacitor grounds directly by via in pad. Sometimes I also enhance the via current carrying capacity by soldering the via to solid if via not in pad. I'm using Loctite C400 Sn63 solder.Is this approach destined to fail in some timeframe or no worries, can continue doing this?Thank you in advance

author: wraper
author_rank: Unknown
timestamp: April 02, 2023, 09:23:06 am
content: For hand soldering it barely matters, you may just need to apply a bit more solder.

author: jimtien
author_rank: Newbie
timestamp: April 02, 2023, 09:46:26 am
content: as I know, via in pads is expoxy filled and copper plated on the surface. This will prevent solder paste from migrating.

author: Siwastaja
author_rank: Super Contributor
timestamp: April 02, 2023, 09:54:31 am
content: Even for reflow, it's not always disastrous, depends on the hole size, pad size and paste mask opening. For example, 0.3mm holes suck only a little bit of solder but 0.4mm are much worse. A large pad can afford losing some of the solder, a smaller one not.For hand soldering not a problem at all. You just apply solder until the solder joint looks visually OK, like you always do. If the via sucks out some solder, you will just be adding more, unless you are doing it blind.

author: wraper
author_rank: Unknown
timestamp: April 02, 2023, 09:57:14 am
content: Quote from: jimtien on April 02, 2023, 09:46:26 amVias are not filled unless you order plugged or plated over vias.
via stitching in PCB's - Page 1
Forum section: electronics / beginners

author: SnakeBite
author_rank: Regular Contributor
timestamp: March 29, 2014, 07:11:01 pm
content: hello,can anyone please explain me what is the purpose of the VIA stitching in PCB design? what it does? does it only important in multi-layer PCB's?i design 195W DC/DC power supply, do i need to add that to the power tracks ( i have one or maybe two layers PCB)?thanksIdo

author: Neilm
author_rank: Super Contributor
timestamp: March 29, 2014, 07:21:46 pm
content: Via sticking is used in only a couple of scenarios:1) Moving a lot of current from one layer to another. Multiple vias in parallel reduce the impedance of the connection. I was once caught out when a power module I was using put the 5V through a single via - I found the microprocessor module it was connected to wouldn't reliably boot due the the extra resistance in this track.2) EMC purposes. For example sometimes you might see a row of vias around the edge of a multilayer board. This will act as a screen to stop any high frequency resonances between layers in the PCB escaping. (Two planes in a PCB can create a good antenna.)Neil

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 29, 2014, 08:20:59 pm
content: In my opinion, a board should always be covered by ground plane (in the respective areas where it is acceptable: obviously, you don't want ground plane spanning isolation barriers, for instance). This provides the best noise immunity and signal quality.A four layer board can often be made with unbroken planes on the inner layers, but a two layer board must have slots in one or both planes due to routing. Every trace that crosses the ground plane causes a slot opening in the plane, which disturbs the flow of currents across the plane.So, simply, everywhere there is a slot, if at all possible, you arrange traces on the opposite side so they avoid the slot, or cross it perpendicularly, and short across the slot(s) between layers with vias.The density of vias need not be great. For casual circuits (audio, digital logic, that sort of thing), one via every 20-40 mm is fine. If the opening spans less than 20mm, stitching across it is probably not even necessary.Low impedances and high frequencies require more vias, so that in the 10GHz+ range, vias might be placed every mm. Or you may need those vias to carry heavy currents, or to keep inductances low (a trace crossing a slot exhibits far greater inductance than a trace over solid ground plane).Even if you don't need the signal quality or current capacity or any of those benefits, it's still a good idea because flooding the board improves manufacturing (the copper density is more even, so the board is less prone to warping), and leaving floating copper (islands or thieving) is poor design practice.Tim
Vias in BGA pads (for one-off prototyping) - Page 1
Forum section: electronics / beginners

author: stevenhoneyman
author_rank: Regular Contributor
timestamp: September 27, 2015, 08:10:46 pm
content: I'm at the point where I need more stuff in less space, so will hopefully be using some BGA packages. The problem is either I spend $$$ on a PCB that will allow vias small enough to fit between pads and 4-5 mil traces for the same reason, or I put vias in the pads themselves.Of course for mass production unless they're capped it's asking for a disaster. But how about for one-off prototyping/hobbyist boards? Has anyone done this and had a good amount of success?I could easily plop a couple of small solder balls in the hole before applying paste/flux... or try sticking with HASL in the hope it does the job for me and the rest of the pads aren't too uneven

author: stevenhoneyman
author_rank: Regular Contributor
timestamp: September 27, 2015, 10:07:35 pm
content: Thanks for the detailed replyQuote from: evb149 on September 27, 2015, 09:47:24 pmFirst thing to go (being the biggest package in use) would be a 144-ball, 0.8mm pitchQuote from: evb149 on September 27, 2015, 09:47:24 pmOh I'm quite sure it'll take some practice to get right! The cost of the 1 part is equal to roughly 10x PCBs, so I'd try and salvage the IC first and forget about the PCB.It's purely a hobby, so if it takes me a month of practice on whatever the cheapest BGA I can find before I feel confident enough to attempt the first real one then so be it. Time is no issue here.Quote from: evb149 on September 27, 2015, 09:47:24 pmI did get a quote (no special via requirements, just 4/4 with 4 layers), it was $140Quote from: evb149 on September 27, 2015, 09:47:24 pmI'll enquire about the smaller via sizes (after this Chinese holiday is over), good idea.
Vias on pads / metalized holes - Page 1
Forum section: electronics / beginners

author: fsky
author_rank: Contributor
timestamp: October 09, 2015, 09:57:03 am
content: Hello!Look at the examples below.I don't really get why they use vias on metallized holes or pads like that.Is this connected with heat distribution? Does they make it to allow substrate to heat up evenly on both sides,thus reducing the risk of copper pad to fall off during soldering of large components? Or maybe it's rather for something in connection with high current conduction? If I'm right, is it the only reason?I got a THT component footprint with those vias and because I was not able to do such small ones it made me wonder if it's actually necessary. Any ideas?

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: October 09, 2015, 12:00:09 pm
content: Mounting holes are *generally* connected to the ground plane of the board. Vias offer redundancy in connecting to the ground plane as the hole plating can be damaged by screw threads and the pads can be ripped off either side, but they also strengthen the hole against over tightened fasteners which would otherwise crush PCB.I'm not sure about the first picture as it appears to be a component lead so may well be to act as a heatsink, but its hard to say without a wider FoV

author: peter.mitchell
author_rank: Super Contributor
timestamp: October 09, 2015, 12:22:55 pm
content: vias add mechanical strength to pads when soldered, the solder plugs the vias, going through the board anchoring the top part of the pad to the bottom part, thus anchoring the leg to both the top and bottom side of the board.

author: fsky
author_rank: Contributor
timestamp: October 09, 2015, 02:42:41 pm
content: One of the attached pictures is a foto of a hall effect current sensor, ACS756. Those leads are only a low resistance copper conductor, so I doubt the power dissipation is an issue here. However, maybe the footprint has those holes for mechanical strengthening, as mentioned before, given the size of the device (so maybe it could be affected by high vibrations). Thank you for your ideas
Vias size for heat transfer on copper pad on both layers - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: May 06, 2016, 03:01:39 am
content: 1. I have designed a circuit with 10A of current capacity. For large current I have made large copper track on both top & bottom layer. Now to connect both tracks, I have made multiple vias of sizedrill dia: 23.62205 milpad dia: 39.37008 milVias are connected so that heat can be transferred between both tracks equally on top & bottom.A)What is the ideal vias size for this kind of purpose.B) I have found one chinese PCB, they have vias spread acorss track. What is size of vias in attached pics?2. I have attached gerbers EVM of bq24650. On top layer it has IC bq24650 with 9 micro vias benath it. What is tehre size. I think it is 0.010 inch as mentioned. Is it tht small?What is drill & pad size for this via?3. I have to design a heat sink for PCB. On locla market I have it just a Aluminium which has been tooled for this purpose. But on internet I was reading heat sink are of particular AL alloy. Does that mean I should get it tooled from some reputed manufacturer only?AL alloy have better thermal conductivity but do they have better thermal dissipation also?
Vibration Sensor Latch Circuit - Page 1
Forum section: electronics / beginners

author: Jabberwock
author_rank: Newbie
timestamp: July 08, 2021, 02:16:53 pm
content: Hi, need some help to make sure this schematic will work before I build it.If there is any vibration the sensor will wake up the MCU. The MCU can then send a signal to shutoff the circuit and by doing so, there won't be any power consumption.I'm unsure if there will be any problem with VCC being tied to the vibration sensor. Is there a need for a resistor there? The mosfet gate as far as I understand should not take any current. So the lower current rating 0.2mA of the vibration sensor should not matter, right?

author: Ian.M
author_rank: Super Contributor
timestamp: July 08, 2021, 02:38:50 pm
content: You've neglected the inrush current into C1 when the sensor first closes, which could easily peak at hundreds of mA. Also, if there's any vibration when Q3 is operated to shut off the power, it effectively crowbars the Vcc rail through the sensor and Q3.

author: Jabberwock
author_rank: Newbie
timestamp: July 08, 2021, 02:48:34 pm
content: You are right. I didn't see that.So I should add another 100kΩ.

author: ledtester
author_rank: Super Contributor
timestamp: July 08, 2021, 02:55:15 pm
content: Your 2N7002's look like they have the drain and source reversed. The body diode of Q2 will always be conducting which doesn't seem right - or am I missing something?For that matter, the orientation of Q1 also looks suspect.

author: Jabberwock
author_rank: Newbie
timestamp: July 08, 2021, 03:08:00 pm
content: Yeah, could be as I'm using Chinese IDE...
VIBROTEST 60 Probe pinout  - Page 1
Forum section: electronics / beginners

author: DarkZero
author_rank: Regular Contributor
timestamp: March 07, 2015, 12:54:03 pm
content: Hey all !Is there by any crazy chance that someone knows pinout for this probe. manufacturer is Bruel & KjaerThanks in advance

author: ConKbot
author_rank: Super Contributor
timestamp: March 07, 2015, 05:07:16 pm
content: Start ohming out between pins, and from the pins to the shield. 6 pins could be a wheatstone bridge with sense lines for the excitation, or there could be an onboard amplifier, and just power, ground signal, an identification eprom. If you get a 2 pairs shorted together, and a relatively constant resistance between everything else, then you know its the former.

author: Andy Watson
author_rank: Super Contributor
timestamp: March 07, 2015, 05:49:28 pm
content: http://www.bkvibro.com/fileadmin/mediapool/Internet/PDF-Files/Documentation/Sensors/P_T/P95def.pdf

author: DarkZero
author_rank: Regular Contributor
timestamp: March 07, 2015, 07:49:42 pm
content: Hey all!Man am i glad i found this forum...THANK YOU SO MUCH!
Vici VC99 have I partially fried it or the main dial? - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: May 27, 2017, 12:12:13 am
content: Its 1 of those low end but decent DMM, there's a few clones like Vichy VC99, using the FS9922-DMM4 , with very little input protectionsA few too many times I know I applied voltage when still resistance setting for instance. When I'm turning through the dial settings it seems to easily get stuck on the LCD and lit up the wrong things sometimes as it turns through the dial.If it lands on the right setting, they all seem to work as far as I can tell, and to what seems the normal accuracy/readings.I've had it apart a few times, maybe I have the dial too tight or loose/etc?This happened back in Feb, and I've barely been using it since, so IDK. But when it works, it seems fine. But when it gets stuck changing between settings, I have to turn it off it reset it

author: sleemanj
author_rank: Super Contributor
timestamp: May 27, 2017, 12:56:25 am
content: Clean the dial contacts, reassemble, ensure that you use all the screws to reassemble, don't leave any out accidentally, including the case screws.Leaving out a screw can indeed easily cause dial range weirdness (I speak from experience).
VICTOR 86E usb high accuracy multimeter - Page 1
Forum section: electronics / beginners

author: torr032
author_rank: Regular Contributor
timestamp: November 29, 2011, 03:21:05 am
content: Hi,Has anyone heard of a victor 86Ehttp://bigbyte.by-trade-shows.com/Digital-Multimeter-VICTOR-86E-with-USB-jack-and-high-accuracy.htmlor here straight from manufacture:http://www.china-victor.com/cn/product_data.aspx?ClassID=168&ID=128(notice on first link power supply is 3V, on second it's a 9V battery)just look at his specs and accuracy. This is an excellent multimeter. Display 21999 counts!!! I can't buy him, only two ebay sellers sell them, non of them ships to my country:http://www.ebay.com/itm/VC86E-4-1-2-Digital-Multimeter-AC-DC-Capacitance-Resistance-Temperature-Hz-/180756074556?pt=AU_B_I_Electrical_Test_Equipment&hash=item2a15e6d03c#ht_2958wt_905

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: November 29, 2011, 03:34:30 am
content: Quote from: torr032 on November 29, 2011, 03:21:05 amYou are very lucky, select another brand and model, so to save your self from burning your own money.

author: torr032
author_rank: Regular Contributor
timestamp: November 29, 2011, 04:51:05 pm
content: which one would you recommend in this price tag up to 60$ maybe. He will mainly sit on my desk, I need accuracy, reliability and as much functions as possible. Thanks

author: Unknown
author_rank: Unknown
timestamp: November 29, 2011, 05:20:21 pm
content: Try Dave's $50 DMM shoot-out, plus his DMM buying guide. Even if you don't buy any of the multimeters he reviewed, it should make you aware of what to look for in a multimeter, and what can go wrong. Buying an unknown piece of equipment is always a gamble, especially if it's from an unknown brand.
Video amplifier splitter by transistor - Page 1
Forum section: electronics / beginners

author: Halford
author_rank: Contributor
timestamp: November 24, 2015, 09:26:13 am
content: Hi everyone once again.I'm trying to copy a small design, a Video amplifier splitter by transistor, so that I can hook up my video googles and my monitor together while flying my RC helicopter.I found a nice design that will fit into a very small pcb, so it's perfect for my portable ground station, but there is a connection that I do not understand.the VR2(2k2 in the middle lower part of cirquit) is a potentiometer, but it just hooks up 2 legs out of 3 (not like VR1 on the left).Is it just using 2 legs to make it a variable resistance or it just doesn't show the full circuit? or is it me just been a noob not understanding?here is a pic of the schematics, thank you for your help

author: Dave
author_rank: Super Contributor
timestamp: November 24, 2015, 09:42:22 am
content: Thismight help.

author: Halford
author_rank: Contributor
timestamp: November 24, 2015, 09:48:53 am
content: indeed, thanks a lot
Video: Back to Basics: Practical guide to diodes - Page 1
Forum section: electronics / beginners

author: w2aew
author_rank: Super Contributor
timestamp: November 06, 2019, 10:10:02 pm
content: By popular request, I put together a "Back to Basics" video on diodes. The video doesn't go into the semiconductor physics or any heavy math, it just gives some good practical information about how to think about typical diode behavior (IV characteristics) - from "ideal" behavior, working towards more "real" behavior. It also briefly discusses some of the many different types of diodes. Demonstrations are shown. Links to many of the previous videos I've done on more specific diode types and applications are also included in the YouTube video description notes.Enjoy:
Video Bandwidth of composite cable - Page 1
Forum section: electronics / beginners

author: tiofilo75
author_rank: Contributor
timestamp: April 13, 2014, 05:14:31 pm
content: Hello everyone, I've tried searching for information on the bandwidth of a yellow composite cable but I have not been able to find any exact numbers. Does anybody happen to know what it is? thanks.

author: SeanB
author_rank: Super Contributor
timestamp: April 13, 2014, 05:26:18 pm
content: Should be 8MHz, as that is what a composite video signal requires as bandwidth, and the cable has to support this without too much loss at the high end, where the 2 colour subcarriers are modulated on. If bandwidth is too low you get a loss of colour saturation with the colours looking washed out in PAL, with NTSC you get colour washout and colour shifts so faces go green or blue.This really becomes important with long lengths of cable, as then attenuation of the higher frequencies is more pronounced. not too much problem with 2m of cable, but with 50m it will be noticed.
Video: Basics of a Summing Amplifier using an Op Amp - Page 1
Forum section: electronics / beginners

author: w2aew
author_rank: Super Contributor
timestamp: April 14, 2014, 05:13:50 am
content: Following along the lines of Dave's excellent video #600 which gave an overview of the basics of op amps, here's a short tutorial on summing amplifier configurations with op amps:

author: electronics man
author_rank: Frequent Contributor
timestamp: April 14, 2014, 10:16:37 am
content: Brilliant video, very informative thanks

author: w2aew
author_rank: Super Contributor
timestamp: April 14, 2014, 03:55:17 pm
content: Quote from: electronics man on April 14, 2014, 10:16:37 amI'm glad you found it useful!While I stated it in the video, I maybe should have stated a little stronger that understanding the basic operation of op amps, as shown in Dave's #600 video or in my video on the topic from last year, is a pre-requisite for understanding this video.Thanks again for watching!

author: Witention
author_rank: Contributor
timestamp: April 29, 2014, 05:39:10 pm
content: I've been trying to get my head around "current-mode" op amps (as opposed to "voltage mode"). They seem interesting in that, in a typical configuration (according to a TI app note), bandwidth reduction is only a function of Rf, not the total gain. But I'm not clear on how an op amp can be sensitive to current on its inputs while maintaining a decent approximation of an ideal op amp (i.e., where zero current flows into/out of the inputs).

author: w2aew
author_rank: Super Contributor
timestamp: April 30, 2014, 12:32:36 am
content: Quote from: Witention on April 29, 2014, 05:39:10 pmThe simple answer is - they don't. Current feedback op amps are different in design, and thus don't follow the same rule that the inputs (at least the inverting input) don't draw current.
Video: Basics of R-2R Resistor Networks for Digital to Analog Conversion - Page 1
Forum section: electronics / beginners

author: w2aew
author_rank: Super Contributor
timestamp: March 29, 2013, 03:33:21 am
content: Here's a new video that presents the basics of R-2R resistor "ladder" networks. It shows how Thevenin equivalents and Superposition can be used to easily analyze the operation of the circuit as a simple digital to analog converter (DAC). Some practical examples are shown using an Arduino and a homemade R-2R circuit.