hybridfree/eevblog-posts huggingface dataset:
Very tall SMD LEDs? - Page 1
Forum section: electronics / projects

author: jayeye
author_rank: Contributor
timestamp: February 10, 2019, 01:16:48 am
content: I need to mount indicator LEDs 30mm above the PCB. I'm making fewer than ten pieces of this, so having light pipes manufactured is not an option. I *could* solder some wire to ordinary T-1 (3mm) LED to lengthen the pins, and even twist it so they become surface-mount, but that's way too ugly, and in any case the leads are not stiff enough to keep the LEDs properly positioned. I looked through LED accessories on Digikey, but I can't find anything suitable. Suggestions?/ji

author: djacobow
author_rank: Super Contributor
timestamp: February 10, 2019, 01:20:15 am
content: I wonder if you could "manufacture" a few light pipes using some plexiglass and some careful sawing.

author: sokoloff
author_rank: Super Contributor
timestamp: February 10, 2019, 01:26:21 am
content: For fewer than 10, I'd probably just use a tiny daughter board with pin headers and Dupont F-F jumpers to join the main board.

author: fossil
author_rank: Contributor
timestamp: February 10, 2019, 01:26:51 am
content: Quote from: jayeye on February 10, 2019, 01:16:48 amCheckout out Light Pipes athttps://lcsc.com/products/LED-Light-Pipes_977.html

author: Kasper
author_rank: Frequent Contributor
timestamp: February 10, 2019, 02:23:22 am
content: Search DK for 'light pipe'.

author: georges80
author_rank: Frequent Contributor
timestamp: February 10, 2019, 02:53:19 am
content: If you have a place that sells plastic around where you live (I do...) you can source some small diameter acrylic rod easily. Cut to length and then just sand the ends with some wet/dry fine paper. Instant light pipe. Simple.cheers,george.

author: jayeye
author_rank: Contributor
timestamp: February 10, 2019, 02:54:04 am
content: Quote from: Kasper on February 10, 2019, 02:23:22 amSuccess!https://www.digikey.com/product-detail/en/LPV2-1250DP/492-2426-ND/8595199andhttps://www.digikey.com/product-detail/en/VLP2-D-6/RPC5350-ND/3819305I have no clue why I didn't find them earlier; I think I was looking just in the LED section of the catalog. Now on to figure out what LED of the several thousand options to useIt still amazes me that a piece of molded plastic is so much more expensive than a microcontroller with a billion transistors, but that's supply and demand for you!)Thanks!/ji

author: Kasper
author_rank: Frequent Contributor
timestamp: February 10, 2019, 04:35:42 am
content: Now to choose from the plethora of LEDs and pipes.Some light pipes have a bunch of similar models with different heights and angles that all fit the same footprint. I recommend one of those so its less of a pain when your mech dimensions change.
[Solved]Very weird behaviour of realloc() - Page 1
Forum section: electronics / projects

author: blueskull
author_rank: Unknown
timestamp: March 20, 2016, 10:10:53 am
content: I just got stuck in a bug for hours regarding to realloc. When I initially malloc an array to be very small, say, 1kB, successive realloc in my program won't work and will simply throw an error -- invalid old size or invalid new size, and glibc raises a signal to terminate my program.The point where realloc fails is very close to 132kB, I can understand it is 132KB minus some other local variables -- which makes sense since max local heap size is 132kB.When I set the initial malloc size to 1MB, realloc behaves correctly. What's more weird is I created another program that realloc from 1 byte, a byte at a time, all the way to 1MB, and it works perfectly.Anyone experienced this before? Realloc will not try to allocate memory from elsewhere -- it will stuck on heap memory in some tricky cases.

author: Macman
author_rank: Regular Contributor
timestamp: March 20, 2016, 10:24:09 am
content: This sort of problem normally happens when the RAM gets corrupted. I would check your program very carefully for all memory accesses.

author: dom0
author_rank: Super Contributor
timestamp: March 20, 2016, 10:47:19 am
content: Things like these are usually heap corruption by your program, something that e.g. Valgrind will find in a matter of seconds

author: bson
author_rank: Unknown
timestamp: March 20, 2016, 07:01:00 pm
content: Not sure what you mean by "throwing errors" or "raising signals", but if you're getting a bus error or segmentation fault you're dereferencing a stale pointer or fail to check for errors. realloc() returns NULL if it fails. Otherwise it returns a pointer to the new memory block. If it needs to move the chunk because it can't be extended and needs to be replace it will need a footprint equal to the old memory chunk plus an unfragmented size equal to or greater than the new size, plus some trivial housekeeping data. If the new size is greater than the maximum chunk size it will be allocated on a special large object chain and not subject to the general defragmentation scheme, and each time you extend it you will need a new one. (Beyond some trivial rounding, like 16 or 64 bytes.)

author: sarepairman2
author_rank: Frequent Contributor
timestamp: March 20, 2016, 07:35:56 pm
content: have you considered simplifying the problem by using op-amps and comparators?are you trying to build a matrix or terminator ? why do you need code that advanced?
Very weird result using IR2110 - Page 1
Forum section: electronics / projects

author: Neukyhm
author_rank: Contributor
timestamp: February 24, 2018, 06:49:53 pm
content: Hi there,I have built an IR2110 operated ZVS Mazzilli driver. The idea is to make it work at 113kHz using a big 2kV 136nF capacitor and a ETD59 core instead of a CRT flyback.I built the regular Mazzilli driver and it worked for 15 seconds until MOSFETs burnt. Then I thought about using the IR2110 instead of big and slow gate resistors, so I designed and built the attached circuit. Mosfets are both IRFP250N.According tothis blogthe IR2110 can be used as dual low side driver. Today I have finally tested the circuit. I have to help it in order to begin oscillation, but it's working at >1MHz according to my oscilloscope. Do you guys have any idea why this is happening? It should be working at 113kHz; the other regular mazzilli driver worked at that frequency.

author: ocset
author_rank: Super Contributor
timestamp: February 24, 2018, 08:13:39 pm
content: A load , as such, cannot be seen. Maybe the voltage on the drains of those fets is going above their maximums.?

author: Seekonk
author_rank: Super Contributor
timestamp: February 24, 2018, 09:46:03 pm
content: Did you power the two + pins of the driver with + supply?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 05, 2018, 04:52:53 pm
content: You can't substitute digital parts in an analog circuit and expect it to work.The analog behavior of the original circuit is actually critical to its operation, even though it might not seem like it under steady state oscillation.The improved digital equivalent, of the original analog circuit, is actually an OSC + PLL + driver. Quite a bit more hardware, not to mention protective devices and such.Gate bias resistors are easily solved with smaller resistors, better performance transistors (IRFP260 are ooooooold) or a modest analog buffer. 100kHz is not particularly taxing for this type of circuit.Tim
VFD Board - Page 1
Forum section: electronics / projects

author: Lance
author_rank: Frequent Contributor
timestamp: July 31, 2012, 07:06:02 am
content: I recently found a VFD mounted on a board sitting around. I managed to identify it as an NEC FIP display, and that it uses a National Semiconductor MA1003 as the driver. The board itself is marked as a National product. Thus far I've been unsuccessful in finding a datasheet on the device. It doesn't really help that the device is potted over as well. There are clearly the 6 connecters on one side of the board, one of which is unused. Beyond that I haven't been able to figure out anything else about the board.Does anyone have a datasheet for this driver? If not I might as well go about removing the VFD from the board and trying to drive it manually.

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 31, 2012, 08:47:38 am
content: Well, it says MA-1003

author: Lance
author_rank: Frequent Contributor
timestamp: July 31, 2012, 06:55:18 pm
content: Quote from: PA0PBZ on July 31, 2012, 08:47:38 amThat looks like the same module. I'm wondering what the various input voltages are for the park or signal lines are. At the least I need the ignition pin set active to enable the display.

author: Lance
author_rank: Frequent Contributor
timestamp: August 02, 2012, 09:19:20 pm
content: I tested it, and it works! The trim pot on the back has been soldered into one position, I'll see if I can clean that up. In the mean time, I'll just go about putting it in a housing.
VFD Display 20x2 - Page 1
Forum section: electronics / projects

author: facumedica
author_rank: Contributor
timestamp: April 15, 2014, 09:49:21 pm
content: I need the datasheet of a VFD display. Is marked from NEC, it says FD20X2AA-C. Is quite old, it has some custom chips on it back and two 7408.Thanks!

author: codeboy2k
author_rank: Super Contributor
timestamp: April 19, 2014, 12:47:21 pm
content: I have the following for the NEC FC20X2JA.. it might help.

author: facumedica
author_rank: Contributor
timestamp: April 20, 2014, 09:55:07 pm
content: Thanks! It's not the same but it should give me an idea. I'll take a look and maybe use the Test function and see if it does something.I'll keep you informedThanks again!

author: facumedica
author_rank: Contributor
timestamp: April 21, 2014, 12:26:51 am
content: I'm uploading some pictures, maybe they'll help.There's a simple schematic, I couldn't find the Datasheet of the B6101C055/B6I0IC55Mine has only parallel comunication so there are less pins.Could you give me a hand on this?Schematic (can't upload it here it's a big image. 1.1MB)https://www.dropbox.com/s/46utny2n03lpa39/20140420_211400.jpg]https://www.dropbox.com/s/46utny2n03lpa39/20140420_211400.jpgBye!

author: facumedica
author_rank: Contributor
timestamp: April 21, 2014, 12:30:35 am
content: More attachments!The AND gates are obviously used as buffers.

author: facumedica
author_rank: Contributor
timestamp: April 21, 2014, 01:46:23 am
content: The B6101 it's a gate array. It will be more difficult to know which are the data lines, I though that one was like a controllerDatasheet:http://pdf1.alldatasheet.com/datasheet-pdf/view/127292/NEC/B6101.htmlHow can I control the display without the board which came with it? How can I make a custom controller?

author: facumedica
author_rank: Contributor
timestamp: April 21, 2014, 03:14:26 pm
content: It Is almost impossible to know which pins are whichIf I could find the datasheet of the fg70's or something more obvious I could trace the pins (as I did on a hd44780 lcd).I'm considering to make a custom driver with a PIC micro. I will desolder the glass and start testing!Any ideas for the controller?Bye!
VFD HCS-12SS59T, brauche Programmierhilfe  - Page 1
Forum section: electronics / projects

author: Ditt
author_rank: Newbie
timestamp: February 27, 2021, 05:06:33 pm
content: Hallo,ich versuche das VFD Display HCS-12SS59T zu programmieren. Das Mitglied qrti hat 1987 ein Beispiel in der Programmiersprache "C" veröffentlicht.Da ich aber nur Bascom programmieren kann, ist es mir nicht gelungen den Code zu verstehen. Es gibt bei diesem Display einen Command, mit dem manalle Anzeigen aufleuchten lassen kann. Das habe ich geschafft. Doch irgend einen Character darzustellen gelingt mir nicht. alles bleibt dunkel. Wenn qrti oder jemand anders mir dieHexzeichenfolge der Befehle aufzeigen könnte, wäre das für mich eine große Hilfe.Vielen DankDitt

author: Ditt
author_rank: Newbie
timestamp: February 27, 2021, 06:03:06 pm
content: Here my text translated in English.Hello,I am trying to program the VFD display HCS-12SS59T. The member qrti has published an example in 1987 in the programming language "C".But since I can only program Bascom, I did not manage to understand the code. There is a command for this display, with which you can to light up all displays. I managed to do that. But I can't display any character. Everything stays dark. If qrti or someone else could show me thehex string of the commands, it would be a big help for me.Thanks a lotDitt

author: Ditt
author_rank: Newbie
timestamp: March 26, 2021, 10:38:17 am
content: In der Zwischenzeit habe ich einen C-Programmierer gefunden, der mir das C-Programm in Bascom übertragen hat.Das Programm läuft hervorragend.Ditt

author: coromonadalix
author_rank: Super Contributor
timestamp: March 26, 2021, 02:17:51 pm
content: english forum please

author: Ditt
author_rank: Newbie
timestamp: March 28, 2021, 02:27:47 pm
content: Ok,In the meantime, I found a C programmer who transferred the C program to Bascom for me.The program runs very well.Ditt

author: Simon1234
author_rank: Contributor
timestamp: August 21, 2021, 01:21:41 pm
content: Quote from: Ditt on March 26, 2021, 10:38:17 amHallo Ditt,könntest du mir das Programm in Bascom netterweise zu Verfügung stellen?Habe auch noch ein paar Anzeigen rumliegen, die ich in nächster Zeit betreiben will.Danke vorab.GrußSimon

author: harerod
author_rank: Frequent Contributor
timestamp: August 21, 2021, 04:51:34 pm
content: Guys, have you heard of mikrocontroller.net? That site is infested by German native speakers.

author: Simon1234
author_rank: Contributor
timestamp: August 21, 2021, 10:30:25 pm
content: Quote from: harerod on August 21, 2021, 04:51:34 pmSorry for the trouble. I tried to contact Ditt via a private message, but the forum software says that Ditt's inbox is full. So I had to write here."PM could not be sent to 'Ditt' as their inbox is full!"
VFD reduced voltage question - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: February 06, 2023, 02:10:47 pm
content: Is it possible to use a VFD at half of its rated voltage?For example VFD rated for 480V in and 5HP used with a 240V source and 2HP motor.Probably depends on how far down you can adjust the settings?Anybody do this?

author: TheMG
author_rank: Frequent Contributor
timestamp: February 06, 2023, 02:26:25 pm
content: It will probably complain about insufficient voltage and refuse to do anything at all.

author: wasedadoc
author_rank: Super Contributor
timestamp: February 06, 2023, 07:01:14 pm
content: I was briefly wondering what Vacuum Fluorescent Display runs at 480 Volts until I got to the 5HP part.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: February 07, 2023, 01:56:34 am
content: I've run many on single phase input, but never reduced voltage. I'm guessing you'll get a DC bus low voltage fault if you try it.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: February 07, 2023, 02:02:14 am
content: The DC bus will get pumped during braking of the motor (and that is then again bled of via a "braking resistor"). This means that the internal DC bus is a quite important part of an VFD, and all VFD's will monitor this voltage to check if it is in between allowable limits. So it either won't start at all if the input voltage is too low, or it will give you a DC bus error. (Maybe only at the moment you try to start the motor).
VFD tube clock project - Page 1
Forum section: electronics / projects

author: kodon
author_rank: Contributor
timestamp: February 11, 2012, 03:54:30 pm
content: Check out my almost completed VFD tube clock!One day I noticed a brief tutorial of numitron tubes in hack-a-day. I decided to order a set of those from eBay, but they turned out to be VFD tubes. No worries, they are actually even nicer than the yellow glowing numitron tubes. So I decided to make a small clock project...The clock has an ATmega328 µC and DS1307 RTC with a coincell battery backup. Tubes are controlled with HEF4543 BCD-to-7SEG decoder/latch/drivers. Then there is two UNL2003 IC's and bunch of 0805 resistors/caps... and that's about it.I could have done the tube board with 2 sided layout but I wanted the topside to be clean so I ended up with a single sided PCB. Therefore I had to use lots of that flat cable to power things up.Enough yada yada...Here is the clock in action:It needs some finishing touches with the casing... Maybe a smaller box and holes to be drilled for the tubes. I maybe should have added a 12 Volt regulator and there were few minor bugs but they are now fixed.So, waddya think?

author: Unknown
author_rank: Unknown
timestamp: February 11, 2012, 04:51:24 pm
content: Nice one.And the blue ones look better to me as well.

author: wkb
author_rank: Super Contributor
timestamp: February 11, 2012, 06:01:19 pm
content: Somewhat related: I found this ideahttp://www.ebay.de/itm/Rohren-Oszilloskop-Uhr-Scope-Funk-Uhr-Tube-Clock-/330673234478?pt=DE_TV_Video_Elektronik_Funkgeräte&hash=item4cfda9222e#ht_3662wt_1157rather nice / geeky

author: Mint.
author_rank: Frequent Contributor
timestamp: February 12, 2012, 09:26:36 am
content: Thats crazy! Awesome job!

author: kodon
author_rank: Contributor
timestamp: April 13, 2012, 09:43:47 pm
content: Thanks, maybe I'll post the schematics someday. This was made only for my own amusement, so nothing fancy has been done there with the layout. Also I modularized the project with the display board and the "driver board" to make things nicer (in a development point of view). I tend to be lazy with these things so I figured this is the only way to actually accomplish this project.

author: steve_w
author_rank: Regular Contributor
timestamp: April 14, 2012, 12:39:47 am
content: Good job, now make it so the alarm can be set at a different time for weekdays and weekends and my wife will let me get one :-)regardsSteve W

author: amyk
author_rank: Super Contributor
timestamp: April 14, 2012, 11:19:05 am
content: I like the blue color too.

author: Harvs
author_rank: Super Contributor
timestamp: April 14, 2012, 12:16:24 pm
content: Looks real nice. Great little project.For future reference, there's really no need to buy a separate RTC device when using a ATmega328p (or was that the non-pico power version you had?) The only thing is it's a bit more work getting all the sleep modes sorted when going into battery backup. That and the oscillator pins are the same as the main crystal oscillator pins, so you have to use the internal RC oscillator. Anyway, just a thought that may save you a few $.
VFD Tube Longevity - Page 1
Forum section: electronics / projects

author: tsvisimcha
author_rank: Contributor
timestamp: October 10, 2024, 02:34:23 pm
content: I purchased some pulled Soviet IV-18 VFD tubes. I've found some limited info online about driving them and I have a general idea of what I'm doing but I'm not sure if there are any steps I should take to preserve the longevity of the tubes. Some have said to slightly undervolt them but others have said this can cause issues. Any advice would be appreciated.

author: Xena E
author_rank: Frequent Contributor
timestamp: October 10, 2024, 04:12:34 pm
content: Keep within the ratings.Make sure to not exceed the cathode filament voltage, and don't underrun them, excessively, it can cause poisoning of the emissive oxide layer aim for a variation of no more than +0 –5% of ratings.They normally last a very long while if treated with respect.X

author: tsvisimcha
author_rank: Contributor
timestamp: October 10, 2024, 09:10:14 pm
content: When you say underrun did you mean voltage or current?

author: Xena E
author_rank: Frequent Contributor
timestamp: October 10, 2024, 10:01:27 pm
content: Referring to heater voltage, (but of course underrunning voltage will reduce the current also).Research "cathode poisoning" for reasoning.Keep all other electrodes within published specifications.

author: tsvisimcha
author_rank: Contributor
timestamp: October 11, 2024, 01:13:52 am
content: Thank you much for the assistance!
VGA audio spectrum analyser - Page 1
Forum section: electronics / projects

author: GK
author_rank: Super Contributor
timestamp: September 04, 2012, 02:25:39 pm
content: .

author: poptones
author_rank: Frequent Contributor
timestamp: September 06, 2012, 12:06:25 pm
content: http://www.soundhound.com/It works amazingly well. I recall having it work within about ten seconds one time when we were in a van full of people talking in the background and the cellphone held near a dash speaker.You could always use audio from one of the artists sharing their work on youtube. There's plenty of great artists there who would appreciate the added recognition.
VGA controller using a Basys2 - Page 1
Forum section: electronics / projects

author: Fantasma25
author_rank: Regular Contributor
timestamp: October 11, 2013, 04:42:31 pm
content: Hello, I'm just starting making my VGA controller using an FPGA. I made the horizontal and vertical sync signals and a small test demo that only shows one color. The thing is that I've compared my sync signals with the ones of the demo that comes with the Basys2 board and they are a little bit different. They both have the same sync pulse and front and back porche, but the signals are a little bit delayed. I'll upload the comparison. Is this a critical thing? When I plug both projects to a monitor, they both have the right edge a little bit fuzzy. Thank you!

author: kfitch42
author_rank: Frequent Contributor
timestamp: October 11, 2013, 06:16:06 pm
content: The one thing to remember about the "VGA standard" is that it doesn't really exist. If you get a picture, then you are doing OK. If you really want to be sure you are doing something that will work with many monitors, then you probably want to emulate something that you think(know?) works with many different monitors, e.g. the VGA output from you computer.

author: hlavac
author_rank: Frequent Contributor
timestamp: October 11, 2013, 10:31:21 pm
content: Clock jitter on the Basys 2 oscillator is terrible for generating VGA signals, you may want to fit the optional oscillator in the provided socket and use that as clock source....

author: Fantasma25
author_rank: Regular Contributor
timestamp: October 11, 2013, 11:46:40 pm
content: QuoteThanks for the tip! I will search for a good one.QuoteI'll take a look at that. Thank you!
VGA Monitor Interface - Page 1
Forum section: electronics / projects

author: Chryseus
author_rank: Regular Contributor
timestamp: September 24, 2010, 10:36:05 pm
content: Hey guys!I'm designing a simple 2 lead ECG/EKG machine and I need information on interfacing it with a standard VGA monitor, I'm using a ATMega 48 micro.So far all the information I've found is rather vague and/or confusing, so if anyone can point me to a good article that would be great.Any help on this project is much appreciated, I will be releasing the source and schematic for everyone to enjoy.

author: armandas
author_rank: Frequent Contributor
timestamp: September 25, 2010, 09:35:40 am
content: It's quite simple really. You only need 5 signals:HSYNC - TTLVSYNC - TTLRED - AnalogueGREEN - AnalogueBLUE - AnalogueSync signals depend on the resolution and refresh rate you want to use. As you are using a micro, you'll have limited choices (640x480 @ 60Hz requires 25MHz pixel clock!).The colours are analogue and their intensity depend on voltage.I attached a part of my report, which discusses the implementation of VGA interface. It does not go into details of monitor operation though. You can find that information here:http://books.google.com/books?id=mwUV7ZK9l9gC&lpg=PP1&dq=fpga%20prototyping%20by%20vhdl%20examples&pg=PA257#v=onepage&q&f=false

author: Chryseus
author_rank: Regular Contributor
timestamp: September 25, 2010, 11:42:36 am
content: Thank you that helps a lot.

author: Zad
author_rank: Super Contributor
timestamp: September 25, 2010, 04:07:53 pm
content: You are going to have your work cut out generating VGA with that chip. Maybe you could get TV resolution but 640x480 is pushing it. Epson used to have a great video generator chip, the S1D13806 which had onboard video memory. 4dsystems in Australia do a nice little graphics chip too:http://shop.4dsystems.com.au/38-vga-embedded-vga-graphics-modules

author: jpwack
author_rank: Contributor
timestamp: September 30, 2010, 08:19:05 pm
content: Doing it at a low resolution may work, but just to scare yourself a little, you have to output 3 values at pixel-clock ~= 1.5*{width}*{height}*{vrefresh}, I did once drive a VGA monitor with an Spartan3 FPGA @ 1024x768x60, but it was all done directly, no buffers and in 3 bits of colour (our board did not have DACs AFAIR).The board that Zad mentions looks neat, or maybe use a salvageable RAMDAC from a old videocard too.Cheers
VHF radio modules... - Page 1
Forum section: electronics / projects

author: Precisiontools
author_rank: Regular Contributor
timestamp: April 19, 2013, 11:28:34 am
content: A few years ago (about 7 actually) I was involved in a project where we used Radiometrix VHF radio modules. I have a similar project on my horizon and I have revisited their products and they have had significant price rises and seemed to have cornered the market.Anyone know of any options in this field for 151.3Mhz ISM band data transceiver modules?Thanks in advance.

author: JamesAus
author_rank: Contributor
timestamp: April 19, 2013, 01:01:01 pm
content: In the 151.xxxMhz band you have limited choice. Only other one I know of is Elsema, and depending on which Radiometrix modules you were considering you may find Elsema's offerings less appealing.I don't believe the price of the BiM modules has changed much at all, but that may depend on quantity. Are you limited to 151Mhz or are you open to other ISM bands?

author: mswhin63
author_rank: Frequent Contributor
timestamp: April 19, 2013, 04:02:16 pm
content: I use to use Radiometrix modules, but I purchased mine fromwww.lprs.co.uk. The shipping rates were not too bad although they distribute to Farnell. I think they ceased Radiometrix stuff and worked on their own gear. Mine about 10 years ago though.

author: Precisiontools
author_rank: Regular Contributor
timestamp: April 20, 2013, 09:44:06 am
content: Thanks guys...I am going to stick with the VHF ISM band...my application requires it. Looks like I will stick with Radiometrix for now.Cheers
Valve Guitar Amp Preamp Modification (VHT Classic 18) - Page 1
Forum section: electronics / projects

author: tomsouthtrader
author_rank: Newbie
timestamp: September 21, 2020, 12:26:17 pm
content: Hello EEV Forum!Something slightly different for this forum, however its quite clear that the knowledge and experience of members of this forum is second to noneI have been trying to modify my VHT Classic 18 (basically a cheep Chinese amp based loosely on a Marshall 18w circuit).Essentially I am trying to completely bypass the awe full input gain stage that uses a TL072. And wire the guitar straight to the input of the first preamp tube..I have found the schematic for the amp, and working from that I got the soldering iron out..My aim was to completely remove the TL072 from the circuit and wire the input straight into the tube.The schematic I have attached shows what I have done to the circuit.The amp didn't blow up thankfully.And it does make a sound... And The tone itself is not to bad (at least through the LO input).However it now has a couple of issuesThe input is now incredibly noisy. There is some sound even when the master is at minimum.Also the treble control when turned all the way up makes make an awful noise (almost like some self oscillation). However I had never turned this all the way up before attempting this modification.So I am asking for you knowlage and advice on how to fix my 'mod' <3)Link to the schematic and my 'MOD'..https://drive.google.com/drive/folders/1Q-AdViC60HTd6p0KYzZEajgf1M5A8tYZ?usp=sharingUPDATE..Following some advice received for a member of another forum i have placed the input signal after C52 rather than before it...This worked and achieved exactly what i set out to do, However..Does the input of a 12ax7 need a capacitor inline???And what would be the best way to wire in a volume pot for this input? and any suggestions on a value for it?Also i have now also attached a schematic and how it is wired now..

author: gbaddeley
author_rank: Regular Contributor
timestamp: September 22, 2020, 12:27:12 pm
content: Replace R76 100k with a 1M audio pot. Disconnect C52 from the preamp IC and connect it to the pot wiper.

author: tomsouthtrader
author_rank: Newbie
timestamp: October 05, 2020, 06:21:54 pm
content: hi gbaddeley,Thanks for the reply.I have just tried this. And it resulted in extreme noise and the signal cutting out once both end of the pot are reached!Is C52 necessary for any electrical reason???Thanks again
Via in pad on an 0201 part? - Page 1
Forum section: electronics / projects

author: daqq
author_rank: Super Contributor
timestamp: March 07, 2025, 09:04:28 pm
content: Hello,I'm dealing with a fairly dense board and it would help me to use vias in pads on 0201 capacitors as shown below:Pretty much a 0.5mm via with a 0.25mm hole sticking out of the 0201 pads.I don't work as much with 0201 components, so I would like to ask you whether this will cause any manufacturing issues? The vias are through hole, type VII, so filled and capped. There may be a small dimple, but not too deep.I am however worried about thermal issues when soldering.Is this an okay thing to do, or shall I use a different solution? If not, what about using microvias in the 0201 pad? Would using 0402 parts be okay in this situation (0.5mm through vias)?Thanks!

author: mtwieg
author_rank: Frequent Contributor
timestamp: March 08, 2025, 01:26:36 pm
content: It certainly can be done (so long as the vias are properly overplated, see IPC-6012). There are a lot of factors besides layout that can contribute to tombstoning (component placement, reflow profile, paste print quality, component height, etc), and if all of those are done well you can often get away with murder on the layout. If you're working with a good CM which will profile the boards before real assembly (i.e. not JLCPCB), I wouldn't worry much. Otherwise, I would at least avoid vias directly to large inner planes, and would try to "balance" things by having VIP on both leads. I'm assuming you're at least using blind vias, otherwise you might have trouble routing these traces...

author: electron_plumber
author_rank: Regular Contributor
timestamp: March 08, 2025, 02:07:02 pm
content: I wouldn't place vias of that size under 0201's due to the asymmetry it creates in the copper.Having said that, I've placed microvias under 0201's many times in mass production with no issues. They're small enough to center in the pads without violating minimum solder mask sliver design rules. Obviously, you'll want the vias plated over.

author: daqq
author_rank: Super Contributor
timestamp: March 09, 2025, 08:57:39 am
content: Thanks! So, it's a "Yes, but..." kinda thing. I'll probably use 0402s then, they should work just fine. Gonna take up more space and have a bit less capacitors, but it'll work.

author: Whales
author_rank: Super Contributor
timestamp: March 09, 2025, 09:13:57 am
content: Can you always put a via on both pads rather than just one? That would help the thermal & wicking symmetry.

author: daqq
author_rank: Super Contributor
timestamp: March 09, 2025, 10:18:17 am
content: Quote from: Whales on March 09, 2025, 09:13:57 amOn most I can, but internally (or externally) they'll be connected to a plane. There's a ground plane on the inside and outside and power planes on the inside.
Via in pad with HASL finish for BGA - Page 1
Forum section: electronics / projects

author: Miyuki
author_rank: Frequent Contributor
timestamp: February 01, 2021, 09:10:10 pm
content: Hi, do any of you try HASL over via in pad?I want to try it on a cheap proto board.0.2mm drill size and cheap HASL finish. I hope it will prevent possible solder wicking.

author: brabus
author_rank: Frequent Contributor
timestamp: February 02, 2021, 07:54:59 am
content: You aim to fill the VIA with the HASL solder, don't you? For a single proto board it may even work!No fab would recommend it for a production run, though: there is no stability in this process. A single non-perfectly-cleaned via may wick during reflow, leaving the pad unconnected.Never tried it myself, I always went for the capped vias route.I am very curious with the result, keep us posted!

author: Miyuki
author_rank: Frequent Contributor
timestamp: February 02, 2021, 09:45:13 am
content: Quote from: brabus on February 02, 2021, 07:54:59 amExactly what I want.Will try to order few boards and take pictures of how it will look.
Via in Thru Hole Pad - Page 1
Forum section: electronics / projects

author: dannybeckett
author_rank: Contributor
timestamp: February 15, 2023, 10:44:22 pm
content: Hi guys,I know that vias placed in thru hole pads increase current carrying capability (see attached screenshots for high current pcb device). However I was thinking today if this practice can improve mechanical rigidity of the substrate.If you were to include these additional vias in a pad that will be used with a bolt, would the force needed to crush the pcb increase? If so, I wonder if this technique has been properly tested and assessed?

author: Whales
author_rank: Super Contributor
timestamp: February 15, 2023, 11:24:17 pm
content: I've read that putting compression on solder is a bad idea, it "creeps" over time and then loosens your bolt.I might be incorrect by generalising this, perhaps it only applies in certain situations. Maybe confining it inside vias prevents this? Not sure.

author: thm_w
author_rank: Super Contributor
timestamp: February 16, 2023, 01:38:34 am
content: It will increase the tear out strength, will it increase the compression strength? seems kinda unlikely.Maybe instead describe what you are trying to do.Some screw to board connections will use a wave washer or other spring force to attempt to keep constant pressure over time.https://electronics.stackexchange.com/questions/524791/why-do-some-pcbs-have-these-circular-rings-are-they-plated-through-hole-viashttps://electronics.stackexchange.com/questions/240092/why-do-some-pcbs-put-vias-around-mechanical-through-holeshttps://www.tempoautomation.com/blog/robotics-design-protecting-pcbs-from-thermal-stress/

author: DavidKo
author_rank: Frequent Contributor
timestamp: February 16, 2023, 07:51:11 am
content: Every hole in the substrate decreases its rigidity. Via is only electroplating in the hole. To increase rigidity the Al2O3 substrate can be used (on the other hand ceramic is more brittle), Al IMS or Cu IMS depending on your needs.

author: dannybeckett
author_rank: Contributor
timestamp: February 16, 2023, 09:17:12 am
content: Thanks for the contributions guys. Just to clairfy, I'm not trying to do anything - just saw this technique again recently and wondered whether crush strength would improve as well as current carrying capability.Good point David - perhaps if the vias were lined with a tube or riveted it would help, but as you say standard electroplating is very thin and won't provide any reasonable structural reinfocement.
Via stitching for high current on multiple power and ground planes   - Page 1
Forum section: electronics / projects

author: OwenH
author_rank: Contributor
timestamp: July 24, 2020, 11:11:12 am
content: Hi,I am working on a design using an microcontroller controlled infineon Profet +24 to switch a power bus at 14v - 23v at 10 amps. The PCB is a 4 layer board with 2oz copper on the outer and 1oz copper on the inner layers. At the output of the power switch I have 2 power planes and 2 ground planes to handle the current. The output is to an edge board connector on the lower right side of the PCB as seen in the images. The edge board connector uses the top pins for power and bottom pins for ground.My question is whether it is best to use stitching vias for both the 2 power and the 2 ground planes between the power switch and the connector? or is it better to add vias only at the connector and the switch as shown on the images?I imaging I have enough copper to accomplish this with just the top layer and the bottom layer but it seemed to me it would be better to use all 4 layers since I already have them and it should help with thermal dissipation of the Power profet switch.Any advice is greatly appreciated!Owen

author: ejeffrey
author_rank: Super Contributor
timestamp: July 24, 2020, 04:42:41 pm
content: I would put them just at the connector and switch as shown. Vias in the middle wont carry much if any current anyway and will just create holes in your power planes that increase resistance. They might help a bit with cooling the inner layers, but at only 10 amps over 3 oz copper and what looks like a fairly short and wide run I wouldn't worry about that.
ViaDesigner Pulse Oximeter - Page 1
Forum section: electronics / projects

author: lgbeno
author_rank: Frequent Contributor
timestamp: April 30, 2013, 06:32:43 pm
content: So I'm all setup with a ViaDesigner license from the amp hour and I think that I'm going to try my hand at designing a pulse oximeter circuit. For now ill just use a red led and photo diode to measure a waveform.Basic architecture is to use a opamp and pnp to create a constant current led drive. Then another opamp as a TIA. The output of the TIA will be ac coupled to a gain stage followed by a low pass filter and the a buffer amp to drive a ADC.Anyone have experience with such a circuit or any words if wisdom?I'll use this thread as sort of a project log.

author: babysitter
author_rank: Frequent Contributor
timestamp: May 01, 2013, 08:18:08 am
content: make the led current controllable, not fixed. so you can make it brighter with big thumbs and dim it when a lot of light reaches the receiver. pulse the led to discern from ambient light. its not a pulseoxi, its a photoplethysmograph (if you plot optical attenuation over time) or pulse sensor.written with baby on my knees

author: lgbeno
author_rank: Frequent Contributor
timestamp: May 15, 2013, 06:37:16 pm
content: Thanks for the advice! Sorry I haven't been on the forum for awhile but have been working in this project.I did notice exactly what you are talking about wrt the variability of Rx light through the thumb vs finger. If I use the same led current through a finger, it saturates the diode however works great through the thumb.To address this, I made my current reg variable and placed an op amp to regulate the DC common mode of the Tia output (filtered through LPf of 2meg ohm w/ 2uf). This still presents a problem because that regulator also cancels out my pulse signal because this as well is very low frequency! I thought that time constant would crush it but I can still see my pulse leak through on the current output.It might be time to setup a dac and some logic instead...

author: lgbeno
author_rank: Frequent Contributor
timestamp: May 15, 2013, 06:39:03 pm
content: By the way, like the dedication of staying on the forum while caring for kids. When my two year old sits on my lap I have the hardest time keeping her away from pressing keys in the keyboard. "Super letters" as she calls them.

author: babysitter
author_rank: Frequent Contributor
timestamp: May 15, 2013, 08:46:24 pm
content: OK, you talked about a DAC taking care of the measured signal, so I guess there is a Microcontroller around, too. Use a PWM output and a low pass filter to make a little DAC to control the light intensity. In the µc, you can play with the time constant of the LED intensity regulator however you like it.. even measuring it once, keep it on a fixed value until the fixed value doesnt work anymore because the ADC is over/underfed.Fixed intensity with a resting test person can tell you a bit about the tendency of the blood pressure rising or falling.Yeah, kids are great - mine always wants too see what I am doing, but at nine months still quite easy to keep off of the devices i am playing with
Vias in drain pad for MOSFET - Page 1
Forum section: electronics / projects

author: jmw
author_rank: Frequent Contributor
timestamp: November 13, 2018, 12:31:43 am
content: I'm limited in space on the top side of my board to put a copper pour around the drain of a MOSFET for thermal relief. I know it's common to have exposed pad vias to ground in many ICs, but is good practice to say drop some small vias in the large drain pad to a pour on the reverse side of the board?
Vibing DT Sensors & Mallory Sonalert  - Page 1
Forum section: electronics / projects

author: TrotsKeeper
author_rank: Newbie
timestamp: January 27, 2023, 07:25:49 pm
content: I have two piezo sensors that I want to use to measure heart rate and compare the accuracy of signal:1. Flexible piezo electric sensor(https://www.mouser.ca/datasheet/2/418/5/NG_DS_DT_Series_without_Leads_A-1130506.pdf) - thin, flexible, can be used as wearable2. Piezoelectric transducer(https://www.mouser.ca/datasheet/2/252/AST100Q-1519790.pdf) - smol so can also we used as wearableHowever, I'm not sure if I can actually use this to get the heart rate measurement - I'm not sure if they are sensitive enough. The goal is to connect these piezos to an arduino nano 33 BLE and send the data to matlab. What do you guys think - in your experience, would these piezo sensors be able to detect heart rate if I tape the part around my finger or wrist ?

author: bidrohini
author_rank: Regular Contributor
timestamp: January 29, 2023, 02:57:27 am
content: I never really used or heard of using these sensors as heart rate sensor. For heart rate measurement, these sensors are good.https://www.sparkfun.com/products/11574

author: TrotsKeeper
author_rank: Newbie
timestamp: February 03, 2023, 03:53:56 am
content: I came across them as well - the only issue is I can't use optical based sensor as part of the requirements
Vibration measurement  - Page 1
Forum section: electronics / projects

author: meeder
author_rank: Regular Contributor
timestamp: October 17, 2015, 07:46:24 pm
content: For a archery related project I am looking for a way to determine the vibrations that occur in a riser during a shot.What I want to know besides the intensity of the vibrations and the frequency spectrum of those vibrations.What kind of sensor could provide me with the data needed, I have found vibration sensors but they don't seem to give you the frequency spectrum as well.

author: AndyC_772
author_rank: Super Contributor
timestamp: October 17, 2015, 08:24:50 pm
content: Provided you have an accelerometer that samples fast enough, all you need is to run an FFT on the data and you get the frequency spectrum.

author: AMS
author_rank: Contributor
timestamp: October 18, 2015, 10:44:31 am
content: A 3-axis accelerometer scanned at 4 times higher than your maximum anticipated frequency should be fine. You also can use a piezo sensor (film based ones) and glue it on and sample that at the same frequency (4*max frequency) however Piezo would not give you an absolute intensity. Then as AndyC_772 said just take and FFT in the data.

author: EEVblog
author_rank: Unknown
timestamp: October 18, 2015, 11:28:38 am
content: The right gear for this stuff is from companies like PCB Piezotronics and Bruel & Kjaer. And the Dynamic Signal Analyser is the tool of choice.
Vibration proof 2 pin 10-15A connector for inside vehicle use? - Page 1
Forum section: electronics / projects

author: e-pirate
author_rank: Regular Contributor
timestamp: February 26, 2025, 10:33:35 pm
content: Hi, folks.Any suggestion on 2 pin connector type for like 15A maximum load for use inside (not sealed) vehicle that is vibration resistant (with lock)?Need to connect dash cam PSU to cigarette socket wires and hack it somehow inside to keep cig port free.I have some spare XT60 around, but they can eventually come out cause of vibration, I think.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 27, 2025, 04:02:33 am
content: Anderson Powerpole, popular in amateur radio applications, They have a standard way to put them together for 12V, I recommend following it.

author: Amper
author_rank: Frequent Contributor
timestamp: February 27, 2025, 09:41:42 am
content: I understand your urge to have a lock but realistically they wont fall out. The contacts of amass XT60 or 90 are pretty strong and the worst case is to loose the dashcam for a little while, no fire risk or loss of controlIm not sure where you want to put the connector but if its hidden and both connectors are on the end of a wire just put a ziptie around them and they will never come apart. (between the wires around the plugged connectors)If you wanted to do something in larger numbers i wouldnt do it like this but for a single connection that isnt unplugged regularily...

author: todd_fuller
author_rank: Contributor
timestamp: March 16, 2025, 12:34:36 pm
content: Deutsch DTP
Video - Bushnell Yargade Pro 500 Laser Range finder, teardown - Page 1
Forum section: electronics / projects

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: April 27, 2015, 08:57:28 am
content: Hi,I have made another video where I have teardown of yet another laser time of flight range meter - Bushnell Yardage Pro 500 from around 1999. Please enjoy. Comments as always are welcome

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 27, 2015, 11:23:55 am
content: Hi Alexei,Interesting to see how these thing work. Thank you for a this nice video, I should view some others you made.Just a little comment: when you are showing pictures and datasheets the audio is very weak and hard to understand, and you really should not edit so that it cuts a scene in the middle of a sentence. It did not keep me from watching though!

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: April 27, 2015, 05:22:25 pm
content: Yes, thanks for feedback. I noticed the sound level difference when I was editing it, but after I uploaded video to Youtube I found that difference is much much more noticeable. I will try to figure out how I got it so wrong.

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: April 28, 2015, 05:05:22 am
content: I fixed (I think I did) sound in the video. Had to re-upload it of course.
Video by Unit 3 compliance: "We Need To Talk About Ground" - Page 1
Forum section: electronics / projects

author: Whales
author_rank: Super Contributor
timestamp: June 23, 2022, 03:59:49 am
content: I recently came across a board design with a USB micro B port that had the (unused) USB VCC wire capacitively coupled to ground and the USB shield inductively coupled to ground. To me this sounded like two completely contradictory arguments about how to handle noise (one a noise highpass to ground, the other a noise lowpass to ground).In my searches I came across this video. I'm glad to see I'm not too insane in my thinking.... and yes my design also uses a split ground plane. I was almost there by putting my ADC directly on the spot where I join the two ground planes, BUT some of my signal wires cross in a non-joined spot, so I'll change that now