hybridfree/eevblog-posts huggingface dataset:
Discuss improvements in the design of a latching switch? - Page 1
Forum section: electronics / beginners

author: Crsus
author_rank: Contributor
timestamp: January 15, 2025, 01:08:42 pm
content: In the design of my latching switch, I've noticed that the drive current is relatively low, and I want to increase the power output. What improvements can be made in the design?To increase the drive power of your latching switch design, you can consider improvements in the following areas:Voltage rating: 3.7V to 24V1.Can the power be increased by paralleling two MOSFETs?2.Can improvements be made in the structure and heat dissipation?3.Should an additional transistor stage be added when the MCU directly drives a MOSFET?

author: inse
author_rank: Super Contributor
timestamp: January 15, 2025, 01:25:36 pm
content: Please don’t overcharge us with too much details of your design as well as resolution.If “drive current is relatively low“, what current level are you talking about?Compare the MOSFET gate voltage to the datasheet value first.P.S. How do you get your MCU programmed without ICSP pads?

author: Konkedout
author_rank: Frequent Contributor
timestamp: January 16, 2025, 04:31:28 am
content: What is the desired behavior of your "latching switch"? What are the voltage and current levels? How does it turn off?Maybe you can just use an SCR?These listings are somewhat whack-o. An SCR should have 3 terminals. It is easy to get one rated for several amps and 100's of volts. But...once it turns on it stays on until the current drops down below the holding current which is normally quite low.https://www.mouser.com/c/semiconductors/discrete-semiconductors/thyristors/scrs/?instock=y&sort=pricing

author: WattsThat
author_rank: Frequent Contributor
timestamp: January 16, 2025, 04:48:43 am
content: My magic crystal ball is broken today, you’re asking for physic abilities from us to come up with the multitude of pertinent details you’ve omitted from the post such as:Why did you use a non-logic level mosfet driven by an unknown voltage MCU?Why not a gate driver?What are the load characteristics? Voltage? Current?Do you really expect people to research the parts you used without links?

author: Crsus
author_rank: Contributor
timestamp: January 16, 2025, 12:12:13 pm
content: "This is a contactless switch that uses an MCU to drive a MOSFET.The MCU has been directly programmed without leaving an ICSP interface for in-circuit serial programming.I have limited proficiency in English, which may lead to some unclear or imprecise descriptions on my part.

author: inse
author_rank: Super Contributor
timestamp: January 16, 2025, 12:36:50 pm
content: Ah, it’s doing capacitive sensing via TP5, then whats the switch for?The supplied schematic is barely readable.What current is being switched?What did you measure yet?What supply voltage is the MCU run with?Don’t just give the minimal information if you want answers
Discuss the interference of magnetic field on PCB board - Page 1
Forum section: electronics / beginners

author: Benjam
author_rank: Regular Contributor
timestamp: September 09, 2021, 01:50:09 pm
content: I am a high school student from Texas. I am very interested in electromagnetics. I found that the best magnetic encoder is from Renishaw, and when I was learning about his product, I found this product:https://www.rls.si/eng/aksim-2-off-axis-rotary-absolute-encoderI have a very big doubt. It interacts with the magnet below it through the PCB board. When the magnet rotates, will it generate a magnetic field? The book says, isn't the PCB board to avoid magnetic interference? The changing magnetic field will interfere with the circuit board. The higher the frequency of change, the stronger the interference (because the changing magnetic field will induce current inside the conductor); more than a certain degree, the circuit board may be burned (the principle of the EMP bomb). So does this conflict? ? I am very confused.

author: Manul
author_rank: Super Contributor
timestamp: September 09, 2021, 03:12:52 pm
content: Yes, it is true that changing magnetic field induces electric current. But something being true does not necessarily make it a huge factor. For example, does light from your computer screen heats up your eye retina because of photon absorbtion? Answer is: yes it does. But your eyes does not start boiling and burning, because in this case the heating is absolutely negligible, not even worth talking.It is true, that a precision circuit might be disturbed by changes in magnetic flux. Special PCB layout techniques or magnetic shielding (like mu metal) might be needed. Likely not in this case. Interference is very small.

author: Terry Bites
author_rank: Super Contributor
timestamp: September 09, 2021, 03:38:39 pm
content: emf=NABωA track of say 1mm is one turn (n=1). A is one mm2, B say 10mT, ω=1000rad/s (10000rpm)1*0.0000001*.01*1000= 1uV into an open curcuit. Less than an ant fart.
disintegrated plastic screw threaded hole solution - Page 1
Forum section: electronics / beginners

author: coppercone2
author_rank: Super Contributor
timestamp: February 14, 2023, 02:18:56 pm
content: So if you have a PCB on a plastic substrate that has molded plastic bits that you thread into, you might have ran into the situation before where they disintegrated and you have a front panel thats dangling in the breeze when you press on a button.I tested it and the results were great.1) drill a small hole the size of your screw (probobly M3) in the chassis where the insert goes2) get the insert for the screw that fits into the hole on the PCB3) file the insert down to the correct height, matching with other inserts4) insert screw into insert5) clean with alcohol6) stick a small ball of jb weld over the hole you drilled7) press the insert into it, so the screw goes through the holepress some JB weld around the insert using some kind of implement, like a small wooden stick9) after 10 min cure time, extract the screw using pliers, carefully10) you have a replacement metal threaded piece that is reasonably bonded to the plastic substrate and correctly aligned11) you can put more JB weld around it when its cured to shore it upFinally fixed my wavetek 399 front panel.Billion ways to do this, but this is the best way I found.I know its good because I filed down the brass insert near perfect with a leatherman. There was no tapping, aligning, presuming, liquids (besides cleaning, I mean no god damn epoxy liquids) or heat involved.https://www.amazon.com/HELIFOUNER-Female-Knurled-Threaded-Embedment/dp/B0B38J2VJV

author: RoGeorge
author_rank: Super Contributor
timestamp: February 14, 2023, 10:06:50 pm
content: Depending on the plastic type, fiber fillers hardened with cyanoacrylate might work, too.- Fill the hole with cotton, or hemp rope, or napkin paper, or other similar fiber as a filler.- Pour a few drops ofcyanoacrylate(AKA "superglue").- Let it dry, then drill and make thread.
dismantling a 16X2 LCD to flip a polarizer? Are zebra strips finicky? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: February 14, 2015, 08:54:52 pm
content: I have one of those extremely common 16X2 LCDs that came with an Arduino starter kit.It's blue with white lettersbecause the backlight is white.http://www.electronicoscaldas.com/333-large_default/display-lcd-16x2-el-1602a.jpgIt's held onto the PCB with 6 twisted metal tabs.http://www.wayengineer.com/images/TFT/YX-1602A-1.jpgIf I open it up to see if I can simply flip a polarizing filter to reverse the colours will it be impossible to get everything back in the right position so the zebra strip connects properly?Is there a thin polarized sheet in there like I'm assuming?

author: free_electron
author_rank: Super Contributor
timestamp: February 14, 2015, 09:03:28 pm
content: the polarizer is typically glued to the glass. won;t work

author: wraper
author_rank: Unknown
timestamp: February 14, 2015, 09:04:00 pm
content: First of all it almost certainly is glued to the glass. Secondly you need to rotate the polarizer by 90owhat is impossible because display is not square.

author: dentaku
author_rank: Frequent Contributor
timestamp: February 14, 2015, 09:13:16 pm
content: Quote from: wraper on February 14, 2015, 09:04:00 pmDoh! You're right. I should have realised that

author: Whales
author_rank: Super Contributor
timestamp: February 14, 2015, 09:37:27 pm
content: If you have an old computer/laptop screen you don't care about that's lying around, a piece of the polariser can be cut out by hand. If you disassemble one the various layers fall out like a disused sandwich. I've used this to repair small LCDs with water-damaged polarisers before.

author: elgonzo
author_rank: Unknown
timestamp: February 14, 2015, 09:51:33 pm
content: Quote from: wraper on February 14, 2015, 09:04:00 pmRotating the polarizer 90 degrees is not necessary. Just flipping it front-to-back should do the trick (assuming there is no glue involved).When i was a kid i had a calculator whose LCD polarizer and glass were not glued. Long story short: When i accidentally placed the polarizer back-to-front after a teardown, the display was inverted. I kept it like that, because it made my calculator look cool...

author: dannyf
author_rank: Super Contributor
timestamp: February 14, 2015, 10:04:17 pm
content: QuoteYeah. You may need to heat it up, however.

author: wraper
author_rank: Unknown
timestamp: February 14, 2015, 11:02:38 pm
content: Quote from: elgonzo on February 14, 2015, 09:51:33 pmThat works only for circular polarization AFAIK.

author: SeanB
author_rank: Super Contributor
timestamp: February 15, 2015, 05:10:33 am
content: The LCD polarisers are typically placed at a 45 degree angle, so that they can be viewed by people using polarised sunglasses without taking them off. Those are horizontally polarised to reduce glare, the 45 degree angle makes the display still visible, even though it will be low contrast.
Displacement current, where is it in electronics? - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: July 19, 2018, 04:02:35 pm
content: Although I have done some stuff with the differential form of Maxwell's eq's and with Clifford algebra, I never did enough to understand what the displacement current is (I just did it for fun on my own, not in class with problems/applications/tests)So where/when does it show up in EE courses, dealing with resistors, capacitors, inductors, and semi-conductors?I do have utube, but I'm asking anyways

author: Wimberleytech
author_rank: Super Contributor
timestamp: July 19, 2018, 05:28:59 pm
content: I watched the video. It should answer you question very well.Displacement current is the current that charges a capacitor.It shows up in EE everywhere capacitors are discussed (which includes semiconductors). It may be called "charging current" instead of "displacement current."

author: rfeecs
author_rank: Frequent Contributor
timestamp: July 19, 2018, 06:22:59 pm
content: Quote from: lordvader88 on July 19, 2018, 04:02:35 pmPretty much nowhere. Although sometimes it is mentioned in dealing with capacitors, it is not needed to understand or describe how a capacitor works. It might be mentioned in a discussion of how to apply Kirchhoff's law to one plate of a capacitor or something obscure like that.Where it is mentioned is when you have propagating electromagnetic fields: in antennas, transmission lines, waveguides.Maxwell added a term to Ampere's law:Ampere's law says that a current produces a magnetic field. The term Maxwell added is the displacement current. It says that a changing electric field also acts like a current and also produces a magnetic field.Now, Faraday's law says that a changing magnetic field produces an electric field; the displacement current addition says that a changing electric field produces a magnetic field. So the two coupled fields can create an electromagnetic wave that can propagate through space. This can only be explained by adding the displacement current to Ampere's law.
Display enable vs Data Enable in LCD - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: May 10, 2024, 05:43:43 am
content: In this datasheet:https://ww1.microchip.com/downloads/aemDocuments/documents/MPU32/ProductDocuments/DataSheets/SAMA5D2-Series-Datasheet-ds60001476.pdfI'd like to understand the difference between the functions of pins: page 50, 51Pins PC29 - LCDDISP &Pin PD1 - LCDDENWhat is the difference between LCD Data enable vs LCD Display enable?

author: aliarifat794
author_rank: Regular Contributor
timestamp: May 10, 2024, 06:30:19 am
content: LCDDEN controls the timing of data transfer to the LCD panel, while LCDDISP controls the activation of the entire display.LCDDEN is typically used to enable the data transfer from the LCD controller to the LCD panel. It indicates to the LCD panel that valid data is present on the data lines and should be latched or sampled. LCDDEN is often used to synchronize the transfer of pixel data to the display.LCDDISP is used to enable the entire display. When LCDDISP is active, the LCD panel is turned on, and pixels can be displayed. This signal controls the overall activation of the display, allowing it to show content.
Display for autoranging multimeter? - Page 1
Forum section: electronics / beginners

author: dds
author_rank: Contributor
timestamp: September 04, 2013, 08:38:53 am
content: Is it possible to buy somewhere display like this one ?

author: mariush
author_rank: Super Contributor
timestamp: September 04, 2013, 09:17:21 am
content: I suppose you can custom order some... but you'd need minimum orders of thousands, maybe.Digikey has such custom lcd screens from time to time, but in low number... i guess overstock made for some company... and they're hard to find.There are dot matrix lcd displays with i2c or sci interface (128x128 , 128x32 , x64 etc) which are easy enough to use and you can create custom icons on screen for what you need, but generally they're a bit more expensive because of the driver on the back side ...3-5$ maybe if you buy 100 pcs... for example :http://www.digikey.com/product-detail/en/COG-C144MVGI-08/153-1146-ND/2523706

author: free_electron
author_rank: Super Contributor
timestamp: September 04, 2013, 12:31:36 pm
content: Thereis at least one standard one. It was made for the icl7134 i believe. That is or was an autoranging dmm ic.

author: RoadRunner
author_rank: Frequent Contributor
timestamp: September 04, 2013, 04:51:36 pm
content: i hope this can work for few things.http://www.ebay.com/itm/1pcs-6-bit-segment-LCD-Display-Module-Digital-Seg-LCD-/140918780524

author: dr_p
author_rank: Frequent Contributor
timestamp: September 06, 2013, 08:51:35 am
content: Here you go:http://www.soselectronic.cz/a_info/resource/l/trumeter/APM.pdfYou can search for them by their model number.

author: mianchen
author_rank: Regular Contributor
timestamp: September 07, 2013, 07:00:43 am
content: if it's one off, you can buy a dirt cheap DT830 and just use its LCD...

author: G7PSK
author_rank: Super Contributor
timestamp: September 07, 2013, 07:25:16 am
content: Fluke-29-ll-or-79-ll-NOS-Multimeter-LCD-Glass-Display-Panel-Series-2-ll-/370890447287?ssPageName=ADME:B:FSEL:US:1123http://www.ebay.com/itm/Fluke-83-83-lll-85-85-lll-New-LCD-Glass-Display-Panel-83-3-85-3-/370890432445?ssPageName=ADME:B:FSEL:US:1123http://www.ebay.com/itm/Fluke-21-3-23-3-75-3-77-3-New-Multimeter-LCD-Glass-Display-Panel-Series-3-lll-/331012611528?ssPageName=ADME:B:FSEL:US:1123

author: PedroDaGr8
author_rank: Super Contributor
timestamp: September 07, 2013, 07:34:31 am
content: Quote from: G7PSK on September 07, 2013, 07:25:16 amI have a strong feeling I know where that seller got those displays. Via another seller on ebay. The other seller sold the displays in packs of 8 and 10. Let's just say he likely paid about half the price of one for the lot of 8 or 10. Every now and then this other seller gets a new batch which always seems to end when I have a meeting at work.
Display Malfunction - Pixel column shift - Page 1
Forum section: electronics / beginners

author: GaboBaa
author_rank: Newbie
timestamp: December 06, 2021, 04:15:08 pm
content: Hello to everyone,I am some sort of a beginner in what electronics is concerned, but I try always to search for a solution before asking. Sadly, in this case I have absolutely no idea how to solve this...I bought this display (https://www.amazon.es/gp/product/B099NHLFPH/) last week and I have some sort of a pixel shift problem (see picture attached). The screen shows the image that I'm sending it via HDMI but it is all shifted. It's not a signal problem because the OSD (On Screen Display, the display's integrated menu) also has this problem. The second thing I'm noticing is that the board "thinks" that it's native aspect ratio is 4:3 and not 8:3, because when I set a 4:3 AR resolution (eg. 1024 x 768), the screen is completely filled but if I choose it's supposedly native resolution (1920 x 720), I have black bars at the top/bottom.I know that returning the board is an option, but because I'm abroad right now (where the display was supposed to be installed), I'd much prefer to find a solution...Thank you all and have a nice week!Gabriel

author: devinatkin
author_rank: Contributor
timestamp: December 06, 2021, 04:28:28 pm
content: It doesn't quite fit with everything but it looks like it's trying to display an interleaved signal when it's not getting one and swapping certain lines around. There's clearly something wrong with the controller that it's not detecting the correct aspect ratio, and putting the black bars. But if you can force your output to swap from non-interleaved to interleaved it may fix your problem. It may try and get smart and swap around as you do it so you'll probably want to disable any auto resolution adjustments to make it behave.At least that's the best I can say from the details available (Hope it helps)
Displaying characters and graphics on a TV with a Z80 computer. - Page 1
Forum section: electronics / beginners

author: Volt
author_rank: Newbie
timestamp: December 17, 2015, 08:38:30 pm
content: Hello, my first post!I have been building a Z80 computer for the past couple of months and I have hit a bit of a brick wall, the problem is that I want to be able to plug my computer into a TV (PAL, preferably composite). So have been searching for IC's that may do the trick, I have taken a look a the MC6847, MC6845 and 6561 VIC but their a bit complicated for me at the moment.My main constraint is that I don't want to use a microcontroller (So the Arduino TVout library is ruled out for me), therefor is there a simpler way/IC for printing to a TV screen?Thanks for reading, hope I have given enough info and sorry for bad grammar/spelling.

author: Unknown
author_rank: Unknown
timestamp: December 17, 2015, 08:44:00 pm
content: http://www.waveguide.se/?article=bitmapped-video-interfacePerhaps this will be useful? I've literally just finished reading it.

author: alank2
author_rank: Super Contributor
timestamp: December 17, 2015, 08:46:32 pm
content: This guy is doing it with an AVR, but you might find some good info and ideas:http://www.batsocks.co.uk/products/Other/TellyMate.htm

author: Unknown
author_rank: Unknown
timestamp: December 17, 2015, 08:54:57 pm
content: Actually, thinking about it some more... all the devices you've mentioned are geared up for a 68xx / 65xx type of bus, and rely on shared memory. They might be a pain in the arse to rig up to a Z80 (though possible, you'll need to do some fiddling).What might be the best option is to get hold of a TMS9918/29 instead. The Sega Master System used a similar and mostly-compatible VDC with a Z80 CPU, and the 9918 & variants use their own separate DRAM-based video memory. It handles all the timings and addressing for you, so no need to worry about the black arts of DRAM.IIRC, you write to it just like an I/O port, and would need some sort of interrupt setup so that the video memory is only updated during the vertical blanking interval.Search for a schematic of the master system and you'll get a feel for how it all fits together.

author: Volt
author_rank: Newbie
timestamp: December 17, 2015, 09:40:48 pm
content: I have been looking at your suggestions, I think the Bitmapped video interface may be the best way at the moment until I can get my hands on a TMS9918, it seems simple to build and program for.Thanks for your help
display/screen for rpi capable of cold weather - Page 1
Forum section: electronics / beginners

author: Majoren
author_rank: Newbie
timestamp: February 05, 2018, 04:19:56 pm
content: Hi! im building a project for a rpi + seek thermal, i went outside today with my setup which has a waveshare 3.5a display and after 1min the screen started displaying artifacts and a very slow update rate, desaturation, massive color banding etc... everything that could go wrong went wrong basicly and im wondering if you guys know any screen that can withstand the sub zero temperatures of sweden, we are talking about -20, doesnt have to have touch screen, i could just use a controller/external keyboard but yeah help me out here!requirements (celcius)capable of working under sub zero temperatures (-20C minimum)3.5" up to 5"30hz/30fpsthanks for the help!

author: danadak
author_rank: Super Contributor
timestamp: February 05, 2018, 05:50:42 pm
content: Kyocera, take a look at their automotive displays -http://www.kyocera-display.com/products/auto.aspAlso used in extreme cold environments have been resistive pad heaters.But not for low power designs. Google "resistive pad heater lcd".....Regards, Dana.

author: Majoren
author_rank: Newbie
timestamp: February 06, 2018, 06:56:29 am
content: edit : find them on mouserhopefully they are not too expensive! mouser website seems really f****** slow... any european stores anyone could recommend?edit2: kyocera screens are too expensive, maybe there is a way for me to make my current screen capable of operating in the sub temperatures?thanks but i cant see anywhere to purchase their stuff and it feels like their products are kind of really expensive also, they dont have any backlight so it wouldnt be possible to use the screen outdoors during the day...

author: BrianHG
author_rank: Super Contributor
timestamp: February 06, 2018, 07:07:39 am
content: OLED screens have no refresh artifacts at temperatures even below -40 degrees. Cheap ones do exist, but, good luck finding one in you are not ordering in the thousands or more.

author: firehopper
author_rank: Frequent Contributor
timestamp: February 06, 2018, 01:54:26 pm
content: another method is to use some small power resistors to keep the display warm. dont want it to get hot, just above freezing I think.. or maybe a lil higher..

author: danadak
author_rank: Super Contributor
timestamp: February 06, 2018, 04:37:16 pm
content: Lower cost than Kyocera is -http://www.edtc.com/pop.php?id=1But Kyocera displays outstanding appearance, specs alone do not tell everything.Regards. Dana.

author: Majoren
author_rank: Newbie
timestamp: February 08, 2018, 08:59:53 am
content: how do i connect these to the RPi ?Quote from: danadak on February 06, 2018, 04:37:16 pm
Dissecting/Analyzing an audio amplifier - Page 1
Forum section: electronics / beginners

author: ajcrm125
author_rank: Contributor
timestamp: April 19, 2022, 06:25:34 pm
content: It's been years since I messed around with analog stuff (my day-to-day job is a digital designer) but I'm working on an arcade game and want to better understand how the audio circuitry is laid out. Specifically the opamps and surrounding circuitry.Attached is the circuit for reference. For now, all I care about is everything to the right of the yellow line.So let me explain what I 'think' I know and you guys can correct me and/or fill in the missing pieces.The source signal DAO passes though C32 and R51 to an inverting amplifier implemented by one of the opamp's at 2N. I'm assuming C32 is to create a highpass filter?That amplfier has a gain of -1.2 due to R52 and R51. The output should be centered around 1/2 the opamp's power supply voltage because of the voltage divider created by R53 and R54. Not sure what C30 is for other than to reduce noise on the non-inverting input?R55 and C39 is used for a lowpass filter, and it looks like the other opamp at 2N is being used as a buffer so I'm not sure what R56, R57, C41 and C40 are used for.Finally we have another highpass filter at C42 (?) and a final amplfier using Q1 (which I am less interested in than that opamp stuff).Thanks for any info!-Adam

author: Kleinstein
author_rank: Super Contributor
timestamp: April 19, 2022, 06:50:27 pm
content: The last OP and the circuit part from C39,C40,C41 forms a 3rd order active low pass filter. The configuration is called Sallen keyhttps://en.wikipedia.org/wiki/Sallen%E2%80%93Key_topologyThe high pass fitlers are more like coupling capacitors to get rid of DC offsets, not really filtering in the actual audio band.Audio with an LM324 OP amp is not really high quality - it is normally an OP to avoid for audio use as it produces quite some cross over distortion.
Dissimilar Resistors in Series - Page 1
Forum section: electronics / beginners

author: TheN00b
author_rank: Contributor
timestamp: January 07, 2020, 01:39:35 am
content: Hi all,Wow, it's been a while since I posted. I am in university studying an engineering discipline, and I wanted to come up with a project to further my understanding of circuits. I have decided to make a dynamic electronic load (that can dissipate 50W to 1kW in very roughly 50W steps). To do this, I had to come up with a resistance that would, when put in parallel, roughly equal the 1kW load in 20 individual parts. So I went with a 2.9 ohm load per part, which I know will not let me have exactly 1kW but I can get close enough for my liking. One issue I have run into is heat, but with 3x dissimilar resistors in series (1 ohm, 1.5 ohm, 0.4 ohm), I am having a bit of an issue calculating the heat dissipated per resistor in order to find the correct heatsinks for the resistors. With similar resistors, it is very easy, as I would call on my old friend Ohm to just useCode:p=i^2rper every resistor. However, with different values of resistors, I run into a bit of an issue. Knowing that current throughout a series circuit is unmodified, do I just use that same equation? I feel like there is a complication to it and before I go out and buy heatsinks, wanted to confirm that my logic is sound.Thanks in advance!

author: unitedatoms
author_rank: Frequent Contributor
timestamp: January 07, 2020, 01:51:07 am
content: There is no complication. Each resistor Ra, Rb, Rc in series will dissipate Ra*I^2, Rb*I^2 and Rc*I^2.Go ahead, and let the basic safety be with you (1kW is not a joke, no matter how small the voltage is)

author: james_s
author_rank: Super Contributor
timestamp: January 07, 2020, 01:53:05 am
content: Ohms law is your friend. With anything in series you know the current is the same through all nodes. Since you know the current and you know the resistance of each resistor you can easily calculate the voltage across any one of them and from that you can calculate the power.

author: atmfjstc
author_rank: Regular Contributor
timestamp: January 07, 2020, 02:54:41 am
content: How would this electronic load work, exactly? From your description it seems like you would have 20 sets of 3 resistors each (1+1.5+0.4 ohm) in parallel, each set dissipating 50W, and that you could somehow switch the sets in and out of circuit. Is this correct?

author: TheN00b
author_rank: Contributor
timestamp: January 07, 2020, 04:43:45 am
content: Ah, got it. Thanks everyone! I will be careful definitely.@atmfjstc, it uses relays on switches to control each channel that is connected to a bus bar (parallel) so I can "step" up using the 20 switches on a panel.
Distance sensor linearity improvements - Page 1
Forum section: electronics / beginners

author: Poe
author_rank: Frequent Contributor
timestamp: April 01, 2019, 08:35:46 pm
content: What's commonly done to deal with the exponential output of cheap reflective phototransistor distance sensors?Are circuits used to improve linearity or do they just deal with it in software?NOT the fancy parallax ones (image below) or ToF ones, but the ones which entirely depend on reflected light intensity (above).Thanks again
Distinguishing CMOS logic input and output pins - Page 1
Forum section: electronics / beginners

author: ledtester
author_rank: Super Contributor
timestamp: April 30, 2021, 06:07:25 pm
content: I ran across this video:"How to Identify Unknown Logic Integrated Circuits 4000 series, 5400 series, 7400 series."https://youtu.be/knfW0tOK7iEwhich showed how to determine which pins of a CMOS logic chip were inputs and which were outputs.Basically the procedure measures the impedance of the pin -- high impedance means input and a lower impedance means output.I was thinking of how to automate this with a microcontroller's digital IO pins and came up with this idea:The GPIO pin would first charge up the cap and then switch to an input to see if the Pin Under Test discharges it. If so you could surmise the pin was an output currently outputting a low logic signal. And a similar test to see if the output was outputting a high logic signal. If the pin neither charged or discharged the cap you could conclude it was an input.Questions:- Any caveats to be aware of?- Is there something similar that could be used for TTL logic?

author: ataradov
author_rank: Super Contributor
timestamp: April 30, 2021, 06:35:56 pm
content: Why not just enable pull-up and see if the pin reads as high, then enable pull-down and see if the pin reads as low? If both are true, then it is a high impedance state. Otherwise it is easy to tell if it is an output driven low or high.
Disturbances get into all my PSU - Page 1
Forum section: electronics / beginners

author: uliano
author_rank: Regular Contributor
timestamp: November 09, 2024, 03:23:36 pm
content: These traces come from 3 different PSU. As the disturbance seems coherent among them I'm assuming that it's coming from outside.The grid? How can I tell and, more importantly, prevent it?

author: BennoG
author_rank: Frequent Contributor
timestamp: November 09, 2024, 05:35:30 pm
content: looks more like something injected into the probes (telephone , some relay switching, dishwasher switching heater on / off)

author: uliano
author_rank: Regular Contributor
timestamp: November 09, 2024, 06:07:07 pm
content: Thank for orienting my attention elsewhere. It's always where you're not looking at!This time it was the el chepo PSU of a ledstripe light.

author: uliano
author_rank: Regular Contributor
timestamp: November 11, 2024, 07:18:23 pm
content: Update:By replacing the Chinese, Amazon sold, PSU "Nuova Germany" ("nuova" means "new" in Italian, WTF??) with a Taiwanese, Amazon sold, Meanwell I got *complete* rid of *those* disturbances. And that's good.But then, I started falling into a huge rabbit hole...Under the big disturbances there are smaller ones and I'm afraid I'm sailing to a neverending questWhile I'm still falling, and falling, and falling... I may also have stumbled on a bug of the SDS 1104X HDMore on that in the next days and in an appropriate topic.

author: tszaboo
author_rank: Super Contributor
timestamp: November 11, 2024, 07:45:20 pm
content: Two things. You have to define what's acceptable levels of noise, for functional reasons and for EMI compliance. Nothing is ever noiseless. And improving the probing setup often times are important, because it very well might be that the noise is picked up by the oscilloscope probe over the air and not actually present in the circuit.

author: uliano
author_rank: Regular Contributor
timestamp: November 11, 2024, 08:18:35 pm
content: The crappy PSU had, superimposed on top of the 24 V, a mighty 4Vpp @ 42kHz that gave rise, radiated by 2 meters of led stripes and picked up through the air, to the above signals. That was clearly unacceptable and I got rid of it. Now I have something else I can investigate but, luckily, whith much less amplitude. Given my surroundings I’m aware that I can never hope to be in a quiet environment, so at some point l’ll need to stop.
Divide power using triac ; formula ; calculation - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: December 15, 2014, 10:04:46 am
content: 1. I am using a pure resistive load & have to divide output power by using triac. Ckt has 220V ac2. I have a zero crossing detector output signal at every zero so I get two signal in once complete cycle.3. User can select 0.0 – 1.0 value & according to that I have to output the power .e.g if user have selected 0.5 then I have to output half power during 0-180 phase of ac signal.4. I have some calculation on when to turn on triac which i have attached.5. Plz check if I doing it right.6. If I am doing it right, currently I am calculating angle by hit & trial. But I have to do it in MCU, I don't know how to calculate it otherwise because formula contain arithmetic & trigonometry function as in attached .

author: Andy Watson
author_rank: Super Contributor
timestamp: December 15, 2014, 03:52:05 pm
content: Looks good. I would avoid the real-time calculation and use a look-up table.

author: Zero999
author_rank: Super Contributor
timestamp: December 16, 2014, 11:23:52 am
content: Do you not have libraries for the trigonometry?Yes, use a look up table. Pre-calculate x for the different fractions, using a spreadsheet and include them in an array in your program.

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: December 17, 2014, 03:30:16 pm
content: 1. I have attached a file, in which it is explained how to do phase control.2. First one is equal phase division. Which I have done correctly.3. Second is equal power division. this is what I am trying to achieve, its calculation I had described in post#1.I want to know if I am doing it correctly.
diy 12V ups questions - Page 1
Forum section: electronics / beginners

author: Diyaudio_enthusiast
author_rank: Contributor
timestamp: October 20, 2021, 01:11:14 pm
content: Good day membersI'm making a small 12V ups for routers,modems etc..Main power supply is a 12V 2A wall power adaptor.Secondary power supply is a single 18650 connected to tp4056+voltage boost module.I'm planning to use IRF9530N p channel mosfet for switching.I've attached a rough schematic to show the connection.Please let me know about possible issues with this arrangement.Thanks

author: Vovk_Z
author_rank: Super Contributor
timestamp: October 21, 2021, 08:06:16 pm
content: Why do you need a switch?

author: Diyaudio_enthusiast
author_rank: Contributor
timestamp: October 24, 2021, 12:36:51 pm
content: Quote from: Vovk_Z on October 21, 2021, 08:06:16 pmto switch between wall adaptor & battery (when mains power down)

author: ogden
author_rank: Super Contributor
timestamp: October 24, 2021, 02:46:56 pm
content: You can buy that thing instead:https://www.meanwell-web.com/en-gb/ac-dc-industrial-din-rail-with-ups-function-output-drc--40a

author: Vovk_Z
author_rank: Super Contributor
timestamp: October 25, 2021, 07:13:37 am
content: The switch can be eliminated choosing the right voltage for the charger.Doy you reaaly need to switch between them if you have protective Shottky (or other type) diodes?

author: JohanH
author_rank: Frequent Contributor
timestamp: October 25, 2021, 04:15:36 pm
content: I've had a stupid charger/powersupply adjusted to 13 V connected to a small 12V lead battery for 6 years now, driving router, wifi access point, network switch, modem and a raspberry pi (using a 12V to 5V DC converter) for 6 years. Foolproof and no circuitry needed.

author: Vovk_Z
author_rank: Super Contributor
timestamp: October 25, 2021, 08:32:35 pm
content: I'm talking about the same.

author: Diyaudio_enthusiast
author_rank: Contributor
timestamp: October 28, 2021, 08:32:33 am
content: Thanks all for the inputMains supply is quite unstable here.When there is repair, we wont be having any power for 8 hours.I'm using this as a learning experience too.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: October 28, 2021, 12:33:11 pm
content: like the others said, the easiest way is to build an adjustable power supply, set it on ~13-13,8V (which is no problem for common 12V devices) and hold a Pb battery in parallel on float charge.Calculate the current drain from your devices and choose an appropriate Ah rated Pb-battery and you're fine to go also for longer than 8h
Diy 150mm HDMI cable, Identifying Spec constraints, HDMI over IDC cable. - Page 1
Forum section: electronics / beginners

author: Stromuslabs
author_rank: Newbie
timestamp: November 19, 2019, 06:52:03 pm
content: Hey there, I want to make a pcb with a interboard hdmi signal due to chassis port placement. In the past ive been making a ridiculous in house interboard hdmi cable using aluminum foil tape around the tdms pairs and their ground. Which worked quite well 70% of the time. To avoid the 80 points of solder and misalignment points of failure I thought it would be nice to use A short 150mm idc cable to a male hdmi board mount like some Ribbon cable drone boards.Ive been looking at specifications and high speed design im not sure if it the cable would need a ground plane or some spec i havnt considered or can calculate. Any advice on looking at specifications to manipulate them over non standard cabling? Ive been thinking of making a proof of concept board to test and learn how to do eye diagram compliance testing but would be nice to be confident of a design before a prototype.As an aside ive also been looking into laying out the impedance matched tdms on a 2 layer board where most documentation implements a four layer design. Any advice on that? Its a relativly short run from the hdmi to the idc mezzanine and should be able to have a uninterrupted ground plane due to the relative simplicity of it, hdmi is a focus but will also have ethernet and usb on the other side of the board.Thank you for any advice on this, i strive to offer my own expertise one day.First post gotta have a emoji.

author: mariush
author_rank: Super Contributor
timestamp: November 19, 2019, 07:07:26 pm
content: I really have to ask why, when you can buy 15cm or 30cm hdmi cables easilyex.https://www.ebay.com/itm/15cm-Short-Cable-HDMI1-4-A-Male-to-Mini-HDMI-C-Male-Lead-Power-Adapter-Cord-Wire/273673930599?hash=item3fb83cc767:g:MrUAAOSwPcVVgikPall kinds of connectors on each here here:https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=15cm+hdmi+cable&_sacat=0If you really want cheap cheap, I'd consider using 2 pieces of cat6a ethernet cable. Each has 4 pairs of wire .. so one could carry the 3 tmds pairs and the clock pair ( and since it's cat6a which has separator between pairs, you should not need the tmds shield wires) and the other can carry all the other crap (5v, i2c ddc, ceac etc)

author: Stromuslabs
author_rank: Newbie
timestamp: November 19, 2019, 07:18:49 pm
content: Why indeed. When i looked a year ago I couldnt find 100mm hdmi cables specifically right angle ones then moved to 150mm custom job through prototypes. I like the twisted pair idea for future designs. I think ill jump on the quick 3$ right angle here and call it a day. I am still interested in a twist on idc could work for high speed differential signals as they are easy to get manufactured with dirtycables or by hand
DIY 30-0V Power supply project - Page 1
Forum section: electronics / beginners

author: Grzegorz2121
author_rank: Contributor
timestamp: January 29, 2017, 01:20:15 pm
content: Hello everyone!Some time ago i decided to test my knowlege and practice about electronic by creating my own power supply.My first few prototypes had very big problem - voltage on the output was unstable and it was oscillating when I attached a load.My most succesful prototype didn't have that problem but voltage couldn't go up to 30V.(that was just OP AMP with transistor and feedback)I want to create power supply that will use buck module to minimalise power loss due to heat and linear module that will smooth out voltage from converter.Both block should be controllable by DAC from uC 0-5V corresponds to 0-30V(so i will be able to put uC to control these)My converter circuit works fine (i hacked buck module using op amp so i can control it with 5V-0V)But my linear circuit is garbage.Can you help me design linear section of this power supply?I have no idea how to drive BJT and create feedback that won't oscilate.

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 29, 2017, 02:28:42 pm
content: What do you have for the linear regulator so far?Does it work on it's own without a switcher before it?You use a small current source to drive open the output transistor.Then setup an opamp as an error amplifier for the voltage and have it draw the base current away from the transistor when the voltage is to high.I would set the switching preregulator to keep the collector-emitter voltage of the output transistor steady rather than keep a second supply voltage relative to ground.Look up a servicemanual for a comparable HP supply and have a look at the schematic.
DIY 50/600 Ohm BNC termination? - Page 1
Forum section: electronics / beginners

author: Thilo78
author_rank: Regular Contributor
timestamp: April 11, 2016, 04:31:52 pm
content: I'm currently starting to play along with a 200 kHz signal generator I picked up at the recent hamfest.Now I seem to find myself in need of proper termination on my BNCs. Not surprisingly, to be honest.At least I found the signal to disappear when I daisy-chain to scopes via BNC...Now, instead of spending serious money on ready-made terminators, I wonder if it's feasible to build your own from BNC connectors and 50 or 600 Ohm resistors (depending on application)Actually, it should be no problem, but I'm not totally sure about the quality of the resistors and the power rating.Given that my siggen delivers something around 10 Vpp into 1 Megohm, I'd expect to need approximately 2 W rated power for a 50 Ohm terminator.Am I thinking the right direction so far?

author: vindoline
author_rank: Unknown
timestamp: April 11, 2016, 04:39:31 pm
content: Check out this thread:https://www.eevblog.com/forum/projects/home-made-feed-through-terminator-for-bnc/
DIY Aux In connection to car stereo JVC KD-G161 - Page 1
Forum section: electronics / beginners

author: Mikolaj1110
author_rank: Newbie
timestamp: December 13, 2023, 09:26:43 am
content: I soldered the AUX IN cable as in the diagram, added capacitors. In the diagram, pin 4 is GND. I insert a CD with a silent recording and unfortunately nothing comes from the smartphone. I will add that I am a complete amateur in these matters. The soldering went quite smoothly, no cables touching or soldering. I read threads somewhere that in a similar radio they cut off the beams from the CD stereo, but how to do it (link to the thread below) and then solder R and L. I also tried without capacitors.https://electronics.stackexchange.com/questions/420007/diy-aux-in-connection-to-car-stereo-jvc-kd-g151

author: p.larner
author_rank: Frequent Contributor
timestamp: December 14, 2023, 11:34:55 am
content: what has your phone got to do with this?.
DIY Bench power supply 0-24V 10A - Page 1
Forum section: electronics / beginners

author: Lekke
author_rank: Newbie
timestamp: May 20, 2011, 04:53:09 pm
content: HelloI have Powernet 220V -> 24V 10A SMPS laying around and Im in a need of bench supply. I thought that it would be nice and safe to use this power supply since I dont know how to do mains stuff safely. This would eliminate the need for potentially expensive transformer too.Is there any easy way to build bench supply around this? Power dissipated with linear regulation seems a bit high, is it practical for this kinda thing? Are there any smps designs that would be practical for beginner? Tried to google those but didnt come up with anything useful.Just as an brainfart, would it make any sense to buy/build 24V -> 12V dc-dc converter to mimic multiple transformer tabs found in linear bench supplys? That way power loss wouldnt be that high. Sounds a bit silly but I dont know.

author: Zero999
author_rank: Super Contributor
timestamp: May 20, 2011, 06:24:10 pm
content: Building a switched mode power supply is a good idea but using a typical buck converter design to emulate a centre tap won't work. You need to design the 12V SMPs so it can both source and sink current forming a switched mode virtual earth.
DIY Build Oscilloscopes - Page 1
Forum section: electronics / beginners

author: SgtTech
author_rank: Contributor
timestamp: March 21, 2024, 07:17:21 pm
content: I have searched through youtube but cant seem to find if Dave has done any reviews of DIY build oscilloscope kits. He might have got one as a mailbag. I think it would be a nice topic to build and review some on teh EEVblog. I imagine that their accuracy and functions are limited but as a learning tool they have their place I think. I want to build one into a DCC model railway panel so I can see various signals, wave forms, cbus signals etc.

author: Grandchuck
author_rank: Super Contributor
timestamp: March 21, 2024, 08:24:10 pm
content: https://www.amazon.com/s?k=dso+138+diy+oscilloscope+kit

author: Doctorandus_P
author_rank: Super Contributor
timestamp: March 21, 2024, 11:10:07 pm
content: A lot of the DIY contraptions are often some uC with a display. Most (almost) completely skip the frontend. I do sort of like the Yje Tech DSO Shell a bit. It even has a frontend (with some analog muxes) and if the triggering was better, and the thing was less buggy, then I'd even give it a thumbs up.There are some of these on Hackaday, but the maker from the Xprotolab has been collecting info on a bunch of these and listed them onhttps://www.gabotronics.com/resources/hobbyists-oscilloscopes-menu.html
DIY CCFL Inverter circuit - Page 1
Forum section: electronics / beginners

author: kcghost
author_rank: Newbie
timestamp: April 20, 2013, 05:59:44 pm
content: The backlight (CCFL) on my laptop LCD screen is dim, and after some research I found its usually the inverter board at fault.I could buy a replacement board, but that wouldn't be very fun and its not worth it for this laptop. If possible I would like to only use electronics I already have in my house.I don't care about dimming capability, I just need it bright.Before finding out many details, I went ahead and took apart the laptop screen and a standard CFL bulb.I had assumed at the time that the electronics that drive a CFL would be the same or similar enough to drive a CCFL.The plan was to just take out the CCFL inverter board, and wire up 120 volts to the CFL circuit to drive the pins that were previously the output of the inverter board.However the CCFL is driven by two pins, the CFL is driven by four (two on each side of the tube).How far off was I in my assumption? Is it possible to use the CFL electronics to drive the CCFL?What modifications do I have to make?Can I just hook up one of the pair of outputs to the CCFL input? (I doubt that, but its worth asking)If using the CFL circuit is not the best option, are there any other ways to hack up a cheap CCFL inverter circuit?Thanks in advance for any help.

author: SeanB
author_rank: Super Contributor
timestamp: April 20, 2013, 06:12:35 pm
content: Not likely to be the inverter board on an older laptop, more likely the tube itself. The tube is available as a part ( eBay or RS) and is fiddly to install but doable.

author: Alana
author_rank: Frequent Contributor
timestamp: April 20, 2013, 06:17:25 pm
content: CCFL's need much more voltage to start up than heated 4 pin ones. I think computer CFL backlight works on around 1kV [dont try to mesure it yourself - i fried a DMM when i wanted to mesure such circut]. Read about it herehttp://en.wikipedia.org/wiki/CCFL_inverterAnd from my personal expirience with PC and laptop stuff - usually its the CCFL that craps out first so if you managed to disasemble your laptop's screen try finding replacement. Mechanically damaged LCD's are best source for CCFL blubs.

author: amyk
author_rank: Super Contributor
timestamp: April 21, 2013, 08:50:50 am
content: A CFL is just a regular hot-cathode fluorescent lamp that's been packaged together with a ballast. They rely on filaments at each end of the tube to heat the electrodes to emission temperature, whereas CCFLs just need the inverter to supply enough voltage to strike the glow discharge.