hybridfree/eevblog-posts huggingface dataset:
Hysteresis on an LM393 comparator - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 30, 2016, 11:58:09 am
content: I have built a little circuit to read the output from a current sense board, details hopefully attached of the device on the board. It outputs 2.5V DC with no current being sensed. If current is drawn the output rises or falls depending on polarity. I want the LM393 comparator to trip over at 3.7V, and it seems to do this, but looking at a meter and a LED on its output pin this is not a sudden change of state around that voltage. I THINK I need to add a feedback resistor, to add hysteresis? Can someone tell me what value to try and confirm it needs to go from output to the + In pin?Secondly, I want the output to go straight to an inverter based on part of an HEF4069 hex inverter. Will the pull up resistor on the output of the comparator affect the inverter's operation? Is there a better way to get a Low output from the comparator?I attach the schematic of my circuit, don't laugh too much, `tis my first attempt with Eagle"IN" is from the current sense module, "OUT" is to the hex inverter.Many thanks

author: Zero999
author_rank: Super Contributor
timestamp: November 30, 2016, 12:53:12 pm
content: You need a resistor in series with the non-inverting input, as well as a feedback resistor. The data sheet for the LM393 shows how to add hysteresis, see page 14.http://www.ti.com/lit/ds/symlink/lm393-n.pdfWhy are you using the HEF4069 as well as the LM393?

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 30, 2016, 01:03:01 pm
content: Hi Hero999, I am not sure why I am using both, I suspected there might be a more elegant way of doing things, I need the comparator to eventually cause an output that goes LOW when an over current situation is sensed... Is there a better way of achieving this please? I need the hex inverter to invert two other outputs, so it's "there" anyway.Thanks for your reply.

author: Brutte
author_rank: Frequent Contributor
timestamp: November 30, 2016, 01:50:52 pm
content: Definitely a positive feedback is needed. Take a look atEEVBlog #941

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 30, 2016, 05:09:06 pm
content: OK, I have found some time to watch that and it is of great help, thank you for the link.I think if I reverse the reference voltage and the watched voltage on the + and - pins the state of the output will be reversed and do what I need without the inverter? I will test it on the breadboard, I suspect this is why Hero999 asked why I need both? I have much to learn and I am glad I asked here! Thanks again.

author: danadak
author_rank: Super Contributor
timestamp: November 30, 2016, 11:40:54 pm
content: Here is a tool to help calculate the needed R's.http://sim.okawa-denshi.jp/en/compkeisan.htmRegards, Dana.
Hz,on meters - Page 1
Forum section: electronics / beginners

author: M0BSW
author_rank: Frequent Contributor
timestamp: March 24, 2013, 03:39:11 pm
content: https://www.facebook.com/photo.php?v=453435034727884&set=vb.100001841745533&type=2&theaterHz measuring on two really cheapo meters, and the meter I trust ideal 61-322,one of my first videos

author: Sebzy
author_rank: Contributor
timestamp: March 24, 2013, 03:56:27 pm
content: Looks like your image link is broken.

author: retiredcaps
author_rank: Super Contributor
timestamp: March 24, 2013, 09:02:43 pm
content: Herehttps://www.youtube.com/user/pcollinsfamily/videos?flow=grid&view=0
I accidentally shorted live with neutral. Did I damage something? - Page 1
Forum section: electronics / beginners

author: Heisen
author_rank: Contributor
timestamp: January 15, 2020, 08:11:31 pm
content: Hey guys,I have a very old APC UPS (RS 1000) with no batteries installed. It has a surge protection socket at the back. My intention was to use it for an oscilloscope I am about to buy. Where I live the mains voltage is not that stable. So I ended up testing it with my multi meter. I switched on the UPS put my leads in the live and neutral at the back and I heard slight buzzing/squealing noise, when I looked at my multi meter it was on continuity. My house circuit breaker wasn't tripped.After that I measured with the correct way and it works fine. Tested with the load works okay.So the short was for around 3-4 seconds before I realized. Could there be any damage to the UPS? Can I use it for my oscilloscope?Thanks.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 15, 2020, 08:35:35 pm
content: Any decent UPS has some overload protection. Single shot, like a fuse. Or resettable by a thermal/magnetic breaker or electronic circuit.This looks like a decent UPS, and it has an overload LED. Damage to the UPS is unlikely.Your multimeter on the other hand...

author: Heisen
author_rank: Contributor
timestamp: January 15, 2020, 08:47:52 pm
content: Quote from: Jeroen3 on January 15, 2020, 08:35:35 pmWorking Okay.

author: bdunham7
author_rank: Super Contributor
timestamp: January 16, 2020, 04:46:52 am
content: The continuity setting isn't a short--current would be a short--and many meter are pretty well protected even on continuity. If you want to blow things up properly you'll have to use the AMPS function.

author: tkamiya
author_rank: Super Contributor
timestamp: January 18, 2020, 11:45:43 pm
content: Yup, everything should be fine. Lucky you because if your multimeter was on lower OHM measurement or current measurement, it would have either damaged the meter or melted the fuse inside.Even if that happened, current was in order of milli-amps. There is no way UPS could be damaged.I've done that kind of thing many times. I have several cheap meters for times I'm not so sure what I would encounter. Nice bench meter comes out only when I'm sure what I'm looking at, or when accuracy is required.
I am looking for a best practices USB 2.0 reference design - Page 1
Forum section: electronics / beginners

author: Blitzschnitzel
author_rank: Regular Contributor
timestamp: June 01, 2021, 11:29:25 am
content: Hi,I am designing keyboards and for most designs I need a custom PCB. I don’t have much understanding of electronics but most of the time I am just adding switches to an Atmega32U4, so it is relatively simple.However, what puzzles me is how to best implement protection to the USB lanes. So far, I am just adding an USBLC6-2SC6 ESD chip and two 22ohm resistors between the MCU and USB-C port. When I look at other designs, I often see a wide variety of capacitors, polyfuses, ferrite beads, TVS diodes and of course different ESD chips.Is there a good reference design with widely available components that I can copy? Or is there maybe even an IC that combines all this?

author: Blitzschnitzel
author_rank: Regular Contributor
timestamp: June 04, 2021, 09:01:22 am
content: Even the manufacturer's best practice guides vary strongly. I don't know which components are important and which are esoteric fine tuning.

author: Renate
author_rank: Super Contributor
timestamp: June 06, 2021, 12:52:28 pm
content: It seems to me the biggest difference is whether the USB PHY needs external build-out resistors (like the ATMega32u4) or not.After that it's your choice to throw on an ESD chip.Quote from: Blitzschnitzel on June 01, 2021, 11:29:25 amSome consideration should be applied to this too.Using just the internal pullups on external switches doesn't cut it in my book.I like to see some actual current through a switch, a mA or two.You can throw a small cap on it too.

author: Blitzschnitzel
author_rank: Regular Contributor
timestamp: June 06, 2021, 03:07:13 pm
content: OK thx.The switches are actually in a multiplexed matrix, so pullups are not needed.

author: Renate
author_rank: Super Contributor
timestamp: June 06, 2021, 09:36:01 pm
content: Quote from: Blitzschnitzel on June 06, 2021, 03:07:13 pmMmm, I question that.Take the simplest case: one output pin of the µC feeding to a single switch feeding to one input pin of the µC.You're still relying on the internal pullup of the input pin.That means it has an effective impedance of somewhere around 70k.Try running your vacuum cleaner around that and you may get some surprising results.
I am looking for an RS422 Device? - Page 1
Forum section: electronics / beginners

author: jwhitmore
author_rank: Regular Contributor
timestamp: April 11, 2017, 09:18:57 pm
content: Hello all, the subject sort of sums it up but I may well have missed that boat. I'm playing with/learning about RS232, RS422 and RS485 and would like to interface with devices using all of them. RS232 and RS485 as I already have devices that talk using those physical interfaces. RS422 however seems to have slipped away. A search on eBay will throw up any number of interface devices which will convert an RS422 device to USB or whatever but nothing seems to actually use it. I guess given it's a bit more complicated then the other two nobody uses it for simple temp sensors or whatever.I guess I could create two ends of an RS422 interface with a PCB design but both ends could be wrong and I'd never know. If I had something which I was fairly confident was communicating properly and I could communicate with it I'd feel happier.Any thoughts or let it go? I assume that there's a load of 422 legacy kit still used in industry?

author: Paul Moir
author_rank: Frequent Contributor
timestamp: April 11, 2017, 09:31:01 pm
content: RS422 has the same signalling as RS485, just without the ability to have multiple transmitters. Think if it as RS-232 with RS-485 signalling. So you just use a RS-485 driver for it.(Minor note: RS-422 allows for multiple receivers.)EDIT: That's somewhat wrong: they are slightly different in signalling, but I think transceivers use the spec overlap.

author: SL4P
author_rank: Super Contributor
timestamp: April 11, 2017, 09:49:35 pm
content: ...and is often implemented as 4-wire full duplex (effectively balanced RS-232)

author: NW27
author_rank: Regular Contributor
timestamp: April 12, 2017, 03:09:06 am
content: RS422 can also have multiple transmitters and receivers.The significant difference between RS422 and RS485 is RS422 uses four wires (2 for tx and 2 for rx) and is full duplex ie it can receive at the same time that it is transmitting.RS485 uses 2 wires only and is therefore half duplex.You can use RS485 chips to create a RS422 network. As an example of the PC end, set one RS485 chip as a constant transmitter (output enable is a separate thing) and the second RS485 chip (again still at the PC end) as a constant receiver.This gives the four RS422 wires at the PC end.Do similar for the remote end.Also the lines should be terminated and preferably pulled to a known stateSent from my SM-N920I using Tapatalk

author: hendorog
author_rank: Super Contributor
timestamp: April 12, 2017, 06:04:01 am
content: Worth noting as well that you can connect RS422 device(s) to RS485 device(s) - obviously this means the network, and the 422 devices, need to operate half-duplex.

author: jwhitmore
author_rank: Regular Contributor
timestamp: April 13, 2017, 07:55:00 pm
content: Thanks for all the advice it's probably not the best solution but I've laid out a board with 2 x SN65HVD72D chips. I can use one of the for half duplex RS485 and use both for full duplex if I find something to talk to.
i am trying to run a K3011p optocoupler with a 5v 15mA signal. Please help - Page 1
Forum section: electronics / beginners

author: inventoratorspace
author_rank: Newbie
timestamp: September 03, 2020, 04:36:57 pm
content: i am trying to run a K3011p optocoupler with a 5v 15mA signal. It doesn't work though.Please help

author: DrG
author_rank: Super Contributor
timestamp: September 03, 2020, 04:58:29 pm
content: Quote from: inventoratorspace on September 03, 2020, 04:36:57 pmI don't wish to be harsh with your first post, but please understand that you have to provide more information if you want help. How about a schematic or some additional information...the more you provide, the more likely that you will receive meaningful help.data sheet herehttps://www.vishay.com/docs/83504/k3010p.pdf

author: TimFox
author_rank: Super Contributor
timestamp: September 03, 2020, 09:12:35 pm
content: The spec on the K3011P is maximum "trigger" current of 10 mA, but the LED does not have a current limiting resistor onboard. The output device is a triac, not a transistor.https://www.vishay.com/docs/83504/k3010p.pdfHow are you driving it?

author: DrG
author_rank: Super Contributor
timestamp: September 04, 2020, 12:35:16 am
content: Quote from: TimFox on September 03, 2020, 09:12:35 pmI don't know if we will hear from the OP again to find out what he is doing, but as I read the datasheet that I posted, the IFT(minimum, not maximum, trigger current) is 10 mA. The maximum forward current is 80 mA.

author: TimFox
author_rank: Super Contributor
timestamp: September 04, 2020, 02:52:12 am
content: No, that's the minimum trigger current: the manufacturer specifies that a current of 10 mA or more will trigger the device. The 80 mA is the safe maximum level.

author: DrG
author_rank: Super Contributor
timestamp: September 04, 2020, 03:21:47 am
content: Quote from: TimFox on September 04, 2020, 02:52:12 amDid you read what I wrote and did you read what you wrote?You: The spec on the K3011P is maximum "trigger" current of 10 mA,Me: IFT (minimum, not maximum, trigger current)is 10 mA.You: No, that's the minimum trigger currentDid someone put acid in my coffee again? *damn* I hate that when it happensMe:The maximum forward current is 80 mA.You:The 80 mA is the safe maximum level....and BTW: As too many EEs have reminded me, approaching the maximum forward current, without exceeding it, can still result in problems with power dissipation...and so on and so forth...turns out all (or at least most) of those measures have meaning - whodathunkit?

author: TimFox
author_rank: Super Contributor
timestamp: September 04, 2020, 01:49:45 pm
content: Oops--I was decaffeinated when I wrote "maximum". The 10 mA spec is what is required to trigger the unit. For this spec, max and min can be confusing.
I bought a stepper motor without a datasheet - Page 1
Forum section: electronics / beginners

author: Clear as mud
author_rank: Regular Contributor
timestamp: July 16, 2013, 05:02:59 am
content: I see there is a topic from a few days ago "Would you buy a stepper motor without a datasheet?" Apparently I would, because I did. But I am not sure I can figure out all the wires.http://www.allelectronics.com/make-a-store/item/SMT-118/16-WIRE-STEPPER-MOTOR/1.htmlIt's a surplus motor, apparently designed in the 1970s. I bought three of them, and the one I examined closely had a date of 1984 stamped on it.Made in Belgium# PD 12. Code number : 9904 112 12001. 3 Deg. 45' step angle. 175mA. 150 g/cm torque.All that information is directly from the label on the motor. I figured out the 3.75 degree step means 96 steps per revolution. if I turn the shaft by hand, with everything disconnected, I can tell it has 96 detents per revolution. Feels like detents, but maybe it is due to magnetic forces? The one user comment on the All Electronics site where I bought it says two things:1. This is a 8-phase unipolar stepper motor.2. This is listed in the Philips Data handbook CM6 04-77 (1977).I looked for that handbook and was unable to find it. I found a Google Books listing for it, but no text. I found it listed on the LibraryThing website, as being in someone's personal book collection, but I get no results on a WorldCat search. Does anyone know where I might be able to find this book and look at the pages that list data for this motor?The 16 wires are clearly in eight pairs, each with one solid color and one white with a color stripe. I checked with a multimeter, and I get about 24 to 30 ohms between each pair, and no continuity between wires of different pairs. So, the unipolar 8-phase thing seems correct, but how do I know the sequence to drive them? If I hook up any one of the eight pairs to 5 VDC (which should not exceed the rated current too much, based on my resistance measurements), the motor shaft jumps. Then I hook the same pair up backwards, and the shaft jumps again. I hook it up backwards again, and it jumps again. Each jump is always in the same direction, for the same pair of wires (but I think it is different, for different pairs), and each jump takes the shaft 3 degrees and 45 minutes around the circle. This is not exactly what I expected. If the step size is 3 degrees and 45 minutes, then I expected each pair of wires to take it eight times that distance. I thought I would have to hook up the next phase and then the next one, to go another 3.75 degrees each time. Well, actually, I guess I am going twice the step size before I hook up the wires the same way again, but it's still less of a jump than I expected. And again, how do I tell the difference between the eight pairs? If the difference between them is so tiny, and the motor already has 96 detents, am I just landing back in the detents when I disconnect the wire, no matter which pair I use?I think disassembly of one motor might be required, to see how the windings are arranged. And then I'll have to order more of them if I can figure it out, and if I have to destroy the one to get it apart.
I bought new Fluke TP88 Rigid Back Probe Pins and they're magnetized - Page 1
Forum section: electronics / beginners

author: Nocturnal
author_rank: Newbie
timestamp: December 25, 2024, 11:18:29 pm
content: I tried measuring a resistor, and the resistor stuck to one of the probes. Is this normal behavior for these tips? What's the best way to demagnetize the tips (if it's safe to do so)?

author: TimFox
author_rank: Super Contributor
timestamp: December 25, 2024, 11:25:46 pm
content: Try these, maybe:https://www.mcmaster.com/products/demagnetizers/mobility~portable/demagnetizing-area-depth~1/

author: GLouie
author_rank: Regular Contributor
timestamp: December 26, 2024, 06:59:58 am
content: Easy to magnetize steel probes with so many magnets around, even the Fluke TPAK meter hanger. I see no reason to not demagnetize (degauss), I use my old analog tape demagnetizers, such as head demagnetizers or tape erasers. An old fashioned soldering gun works, too, if it has a big heavy transformer and a way to get the item near enough to it (not the soldering gun tip). My tools often get a little magnetized, such as getting close to a loudspeaker magnet. I've never tried one of the permanent magnet devices linked.This also means your resistors have cheaper steel wire (probably clad with copper or the like) which I think is not optimal.
i broke open this stop watch now idk what to do with it - Page 1
Forum section: electronics / beginners

author: SS_Jet
author_rank: Newbie
timestamp: September 08, 2022, 09:18:42 pm
content: i have no experience with electronics so i came here to see what i should or could do with itthe model is a kadio kd-6128you should be able to see the insides with the picture i included

author: SS_Jet
author_rank: Newbie
timestamp: September 08, 2022, 09:23:29 pm
content: close up picture

author: Brumby
author_rank: Unknown
timestamp: September 09, 2022, 12:24:32 am
content: Very hard to see anything with those photos.For starters, it's not good practice to have bright light sources in the shot - such as windows (during daytime) and reflections of such. Have any lighting behind you.Second, either you have:- focus set incorrectly- there was movement during the exposure- contamination on the lens- the quality of the camera is pooror a combination of these.It does look like you have easy access to connections and buttons, so it might be quite easy to repurpose.

author: Brumby
author_rank: Unknown
timestamp: September 09, 2022, 12:34:23 am
content: Presuming it still works, you could try adapting it to any number of timing projects.A run timer for Hot Wheels time trials for example - or a lap timer. You would need to work out a means of automatically triggering start and finish - perhaps with some custom electronics (which needn't be too fancy).Anyone else have some suggestions?

author: xrunner
author_rank: Super Contributor
timestamp: September 09, 2022, 12:40:39 am
content: Does it have a speaker (looks like one on the back), and what stop watch event triggers the speaker sound? You can sense the driving signal to the speaker and with a bit more electronics you can trigger a relay or other event. I don't know what your skill level is though.

author: Terry Bites
author_rank: Super Contributor
timestamp: September 10, 2022, 11:41:00 am
content: fix it?

author: Brumby
author_rank: Unknown
timestamp: September 10, 2022, 12:42:32 pm
content: There's no statement that it's broken ... just broken open.

author: Muttley Snickers
author_rank: Unknown
timestamp: September 10, 2022, 12:50:58 pm
content: Many here so eager to assist and never felt so frustrated that they cannot.
I broken my oscilloscope  - Page 1
Forum section: electronics / beginners

author: mava70
author_rank: Newbie
timestamp: January 05, 2016, 10:38:36 pm
content: Hello, I bought an old beckman industrial circuitmate 9020 that works for few days. Today I was trying to repair a LCD and I am using my scope on the power module of the LCD. I was probing the signal after two capacitor at the power input of the LCD (few volt I think), after some time my scope stop working, power light won't light on and there is no sign of life. I checked the 220V 350ma fuse and is ok.Can be my fault or not?Marco

author: KJDS
author_rank: Super Contributor
timestamp: January 05, 2016, 10:48:20 pm
content: What did you clip the ground lead to?

author: dav
author_rank: Regular Contributor
timestamp: January 06, 2016, 02:17:07 pm
content: EEVblog #279 - How NOT To Blow Up Your Oscilloscope!
I built a wire tracer. Help me understand how it works? - Page 1
Forum section: electronics / beginners

author: Moph
author_rank: Newbie
timestamp: March 25, 2019, 02:58:04 pm
content: Hi guysFirst things first - I'm an electronics nub. I have a very basic understanding of electrical theory and can usually fault-find and repair stuff that breaks around here, but mostly I just tinker until it works.Going back a few years we had some dead irrigation solenoids (buried, of course) at our new house that I needed to find. Hooked up a solenoid chatterbox but no joy, so I had the bright idea that if I could introduce a strong signal to the wire, it would produce stray EMF that I could then pick up with a sensitive receiver. Effectively a tone injector and receiver, I guess.So I hooked up an old shed stereo to the primary coil of an 8Ω step-down speaker transformer with the secondary coil (5W tap) connected to the wire I wanted to trace and to a ground stake. I burned an repeating two-tone audio track onto a CD, played it via the stereo and figured that would work as a tone injector.For the receiver I picked up a Jaycar pre-amp and 3.5A amplifier module. I wired up the pre-amp to a bunny ears TV antenna, hooked up the pre-amp output to the amplifier input, and connected a small speaker to the amp output with a 9V battery to power the lot.The result? This Frankenstein's monster actually worked. With the tone injector in the back shed and hooked up to the active wire of the solenoid that I wanted to trace, I was able to find the dodgy solenoid buried under the front lawn to an accuracy of about 100mm. I could also detect a weaker signal from another solenoid in the garden (known location) that must have been returning via the common neutral wire.A couple of Youtube vids and pics - I only took them at the time to forward to my dad (ex-sparky; hoped he could tell me what I'd built) so excuse the lack of commentary / detail:Initial concept test:Locating the solenoid in the front yard (Youtube description has further details / pics linked):The receiver / scanner:Stereo connected to primary side of 8 ohm transformer; wire to be traced and ground stake connected to secondary side:Can anyone enlighten me as to how exactly this is working? Could I have left out the speaker transformer and just run the 'tone injector' from the stereo amp directly, or was the transformer boosting voltage as I somewhat intended? Was the ground stake necessary or would it work better hooking up the other end of the tone injector to the solenoid neutral? I honestly have no idea what I built or how it works and it's been bugging me for years =)CheersMoph

author: Zero999
author_rank: Super Contributor
timestamp: March 25, 2019, 03:24:37 pm
content: Look up capacitive coupling.The higher the voltage the better, so the speaker transformer to boost the voltage was a good idea.Connecting the 0V of the receiver would also increase the sensitivity.

author: Moph
author_rank: Newbie
timestamp: March 25, 2019, 03:42:04 pm
content: Ah thank you, I didn't know what to google. Reading up on it now =)
I cannot find the diodes in this project ! - Page 1
Forum section: electronics / beginners

author: Hextejas
author_rank: Frequent Contributor
timestamp: October 03, 2018, 09:33:35 pm
content: Here is a picture of the final project as it is all stuffed into the box.I dont see anywhere where he gets from AC to DC. I dont see any diodes on the power supply.And here is a link to the project.http://www.circuitbasics.com/design-hi-fi-audio-amplifier-lm3886/#Required-Transformer-Power

author: Gyro
author_rank: Super Contributor
timestamp: October 03, 2018, 09:38:05 pm
content: Right next to where the transformer secondary leads are connected to the PSU PCB.

author: mc172
author_rank: Frequent Contributor
timestamp: October 03, 2018, 09:39:32 pm
content: The diodes are in TO-220 packages.

author: schmitt trigger
author_rank: Super Contributor
timestamp: October 03, 2018, 09:48:12 pm
content: Very likely.4 discrete T0220 components on each side of the supply, sure look like a full bridge arrangement.

author: Hextejas
author_rank: Frequent Contributor
timestamp: October 03, 2018, 10:13:19 pm
content: AHA !!Thanks so much
[Solved] I cannot imagine what this type of LED is called. Do you know? - Page 1
Forum section: electronics / beginners

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 26, 2023, 03:06:42 am
content: Here is an SMD LED. It's used as a back light. Now I know I could buy SMD LEDs, but IDK of any that output the light backwards. Do you?<- Why didn't that work? Ugh...Thanks!

author: ejeffrey
author_rank: Super Contributor
timestamp: August 26, 2023, 03:28:35 am
content: Reverse mount or bottom entry LEDs.

author: ataradov
author_rank: Super Contributor
timestamp: August 26, 2023, 03:29:21 am
content: This looks like a regular SMD led soldered backwards. It may be helpful to see the picture of the other side.Reverse mount LEDs exist, but they usually designed for flush mount with the board, so not in a typical SMD package.Ok, it looks like they also exist in regular packages. The lens size is increased in that case, which makes sense. So, picture of the other side would be helpful for sure.Your bigger issue in finding a replacement would be the color/temperature match, especially with unknown aging on other parts. If there are not a lot of them on the board, you may have to replace all of them to get uniform backlight.

author: Kim Christensen
author_rank: Super Contributor
timestamp: August 26, 2023, 04:39:46 am
content: You mean like this one? Digikey calls them "bottom entry"...

author: ataradov
author_rank: Super Contributor
timestamp: August 26, 2023, 04:50:16 am
content: Those are the ones I was thinking about originally. This is not the bottom entry, this is just a reverse mount. There does not seem to be a consistent naming across distributors and vendors. They will be like regular LEDs, but they will have taller and more square lens to accommodate the board thickness.Like thishttps://forum.digikey.com/t/reverse-mount-smd-leds/3548Mouser calls all of them Bottom View, and then you can filter by the package type to remove the ones you linked.But look on the other side, it might be just a regular LED flipped. It does not sound likely, since pick and place process would be non-trivial, but who knows.
I cannot open the thread in Chrome??? - Page 1
Forum section: electronics / beginners

author: june
author_rank: Newbie
timestamp: October 09, 2013, 07:27:44 am
content: I am just a new one in this forum.I am used to use Google Chrome to open website.But I cannot click successfully the thread I want to do.I am just confused.....

author: Unknown
author_rank: Unknown
timestamp: October 09, 2013, 08:46:32 am
content: Did you try another browser, like Mozilla Firefox or Safari? You don't give sufficient information for anyone to verify your problem, posting a link to the thread/page you're having problem with would allow other users to attempt to reproduce your problem.

author: herctrap
author_rank: Newbie
timestamp: October 09, 2013, 08:49:27 am
content: you need 5 posts to enter the contest

author: june
author_rank: Newbie
timestamp: October 10, 2013, 07:57:57 am
content: This phenomenon hasn't happened today.Next time, I will remember to paste the link here.

author: GreyWoolfe
author_rank: Unknown
timestamp: October 10, 2013, 11:47:15 pm
content: Not sure what the issue is but I use Chrome almost exclusively and have no issue with any part of the EEVblog website.

author: geraldjhg
author_rank: Regular Contributor
timestamp: October 14, 2013, 06:49:19 pm
content: use firefoxit is even easier to print from within
I can't produce a bounced switch signal. What am I doing wrong? - Page 1
Forum section: electronics / beginners

author: billbyrd1945
author_rank: Regular Contributor
timestamp: May 06, 2018, 07:33:12 pm
content: Bought oscope to see difference between bouncing and debounced switch. Began with cheap breadboard buttons to get my "before" tracing. Problem is-- I can't seem to find just the right combination of settings to see any bounce. No need to wire in a debounce circuit until I have a nasty button to compare it to. Every one I try looks clean on my scope. I'm assuming that I'm doing something wrong. Any suggestions would be appreciated. Scope is Siglent SDS 1052DL+, 50MHz, 500MSa/s, with settings of 1.0V, M25.0us. Thank you

author: taydin
author_rank: Frequent Contributor
timestamp: May 06, 2018, 08:06:02 pm
content: To see the signal fluctuations you are expecting, you need to use a switch that is REALLY bouncing. Switches with spring loaded contacts are particularly bouncy and will give you what you want.

author: mcinque
author_rank: Unknown
timestamp: May 06, 2018, 08:26:18 pm
content: Quote from: taydin on May 06, 2018, 08:06:02 pmAFAIK, any switch bounces due to its mechanical nature.Even with 1MHz bandwidth "toy" oscilloscope, you MUST see the bounces.Are you using one shot trigger? Is averaging disabled? How is set the "Acquire" menu?And just to test the oscilloscope settings, try to emulate the bounces by lightly rub the probe tip over the positive terminal of an AA battery or a psu (with the ground clip connected to GND), you should definitely see them.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 06, 2018, 08:39:58 pm
content: Two things:1. Tactile pushbuttons tend to be surprisingly well behaved, and I suppose probably slide switches too (if they aren't dirty?). Maybe try a power switch, or a toggle kind?2. One edge tends to be bouncier than the other, usually closing I think.Also, the time constant arises from the, well, contacts bouncing -- whatever their mechanical resonances are. Usually somewhere in the milliseconds, so look on a similar time scale.Tim

author: ogden
author_rank: Super Contributor
timestamp: May 06, 2018, 09:55:21 pm
content: I am afraid that you are not using resistor in your test circuit and pull-down resistor is 1Meg of your scope input. Most likely that's why you do not see bounce.Try circuit below, with 470 ohm resistor. Note that low pull-up value is for bounce testing only - to get fast signals. Usually you would use >= 10k pullups.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 06, 2018, 11:23:58 pm
content: Try increase timescale to the order of ms /div

author: billbyrd1945
author_rank: Regular Contributor
timestamp: May 06, 2018, 11:48:16 pm
content: Ah ha! Thanks to everyone. I apologize for not including a pic of my circuit. For the record-- I was using 10k for pull down. The 470r made sense to me and the quick brush across the AA battery was a great solution as well. Did them both, got my bounce. Thanks much. EEVblog is the best!
I don't understand switch ratings - Page 1
Forum section: electronics / beginners

author: Stefan
author_rank: Contributor
timestamp: September 20, 2013, 01:10:38 pm
content: Its very embarrasing, but apparently I cannot even read datasheets of switches.Example:Contact Rating: 0.4 VA max. @ 20V AC or DC max.Contact Resistance: 50mOhm @ 2-4V DC, 100 mA.Assuming I'm only interested in DC, what does this imply?I don't even understand why they use VA. After all, if a switch is closed, the potential over the contacts is near zero, and when the switch is open the current is zero. So VA is always very low. Also many switches have different ratings for DC and AC (without even specifying the frequency) how does that make sense? A switch might only need a fraction of the period to operate, so it will essentially see DC anyway.Ok, I'm trying to be a bit more specific:If the switch is already closed, what is the maximum current I can put through it?If I open the switch, what is the maximum permissible voltage spike?If I close the switch what is the maximum permissible surge current?thanks,Stefan

author: AG6QR
author_rank: Frequent Contributor
timestamp: September 20, 2013, 04:29:22 pm
content: Quote from: Stefan on September 20, 2013, 01:10:38 pmThe critical thing happens at the transition from closed to open. How much current can the switch safely interrupt without arcing or welding the contacts together? This will vary with voltage. The rating of 0.4VA says to take the open circuit voltage times the closed circuit current and multiply them together.

author: Zero999
author_rank: Super Contributor
timestamp: September 20, 2013, 05:26:08 pm
content: Yes, the VA matters because when the switch is being opened or closed, it will dissipate a large amount of power for a short period of time, as the voltage/current need to transition from the loaded to unloaded values which can't happen instantaneously. The switch bounces a bit and if the power is too high, the contacts will weld.

author: Jeff1946
author_rank: Regular Contributor
timestamp: September 21, 2013, 01:29:05 am
content: Also with AC when the switch breaks the arc will stop at the zero crossing point vs dc which won't so current rating will be lower for dc.
I don't understand how shading coils work - Page 1
Forum section: electronics / beginners

author: fubar.gr
author_rank: Unknown
timestamp: October 02, 2024, 09:54:37 am
content: https://en.wikipedia.org/wiki/Shading_coilIf I understand correctly, the sum of the two magnetic fluxes (main and 90deg shifted) is still a sinewave that passes through zero. So the chattering problem in contactors should persist.

author: Berni
author_rank: Super Contributor
timestamp: October 02, 2024, 10:06:35 am
content: If you take a closer look at the photo in the Wikipedia article you will notice that the shading coil only goes around half of the exposed magnetic core.So when the unshaded half is crossing 0 and providing 0 attraction force, the shaded part is 90 deg out and providing some attraction. Then when the shaded part is crossing zero, the unshaded part is again out of phase and so it providing some amount of attraction. Once you sum together both of the forces never goes truly to 0.Or a more mathematical way of explaining it. Yes you always get a normal zero crossing sine wave if you sum two sine waves. But you don't always get a zero crossing is you do "abs(sine1) + abs(sine2)"
I Give Up! Correct IDC Tool for Molex Connectors - Page 1
Forum section: electronics / beginners

author: ed_reardon
author_rank: Regular Contributor
timestamp: May 31, 2017, 05:52:40 pm
content: Hello all,Getting nowhere fast here, which is the correct tool for these small IDC type connectors?I have a basic IDC tool for making the more conventional 2-Row (EIDE) type, but naff all in the tool chest for this one.Details here!http://uk.rs-online.com/web/p/idc-connectors/6827104/?searchTerm=6827104&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B367D247C5E5C647B377D247C5E5C647B31307D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D36383237313034267374613D3638323731303426Call me a numpty, I'll take it!Cheers,Ed

author: darrellg
author_rank: Unknown
timestamp: May 31, 2017, 07:38:13 pm
content: According to Digikey, this is the correct tool:http://uk.rs-online.com/web/p/downlights-display-lighting/1295079/?sra=pmpn

author: ed_reardon
author_rank: Regular Contributor
timestamp: May 31, 2017, 08:06:24 pm
content: How much!Typical RS!Cheers Darrelg that's very kind of you to take the time to help numpty here!

author: darrellg
author_rank: Unknown
timestamp: May 31, 2017, 10:40:24 pm
content: That's the price pretty much anywhere. If you have a Dremel with a cutoff bit, you can make one fairly easily. Attached is a picture of one I made about 20 years ago from a piece of plated brass. I think it was a coin return plunger from a slot machine coin slot.

author: rdl
author_rank: Super Contributor
timestamp: June 01, 2017, 12:11:54 am
content: Can't you get that type of connector in a snap together version? I'm almost certain I bought and used some like that years ago. Of course, they may not have been an exact match.
I got my first multimeter! - Page 1
Forum section: electronics / beginners

author: Auggie
author_rank: Contributor
timestamp: February 28, 2010, 03:36:13 am
content: So I was looking to buy a multimeter and the whole time I just kept hearing Dave's voice scream "FLUKE 87!!!" So i got me a Fluke 87! Thanks Dave. Cant wait for it to get here so I can start measuring!

author: Unknown
author_rank: Unknown
timestamp: February 28, 2010, 04:43:30 am
content: Quote from: Auggie on February 28, 2010, 03:36:13 amYou will not be disappointedI think it is the best meter (both value for money and USABLE features) that fluke have made.Regards,Kat.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: April 05, 2010, 07:55:44 am
content: I want to buy one tomorrow. I don't mean order it and wait for it, I mean go somewhere that has it on display. I wanna touch it, feel it and then buy it.I am at Windsor NSW, but will travel.Any recommendations? Who sells this meter?

author: EEVblog
author_rank: Unknown
timestamp: April 05, 2010, 09:50:18 am
content: Tricky Dick Smith used to carry it, but I doubt they have it any more.Don't know anyone close to Windsor who would really have it in the window for a scratch'n'sniff.Unfortunately if you buy it from a shop front you are very likely to overpay.Sadly, it's a very expensive meter in AustraliaThere is a used one on ebay from an Oz seller if that suits:http://cgi.ebay.com.au/Fluke-87-Multimeter_W0QQitemZ320509347637QQcmdZViewItemQQptZAU_B_I_Electrical_Test_Equipment?hash=item4a9fd88735Dave.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: April 05, 2010, 11:52:01 am
content: Quote from: EEVblog on April 05, 2010, 09:50:18 amYeah, we nuttin' out here but banjos and moonshine.QuoteYeh you said it.QuoteI was looking at that too. I cant decide a brand new 179 would be better. I'll get the 87 some day, but for now I just need a digital meter with low sens on the DC.I am using the full featured handheld jaycar (not so) cheapy $140 meter with the 200A clamp that they were selling a few years ago. It's great for working on household power and cars etc. Today I was working on a little comparator circuit on a breadboard and I couldn't figure out why my trim-pots were 'moving'.Then the penny finally dropped that the damn meter was pulling down on the voltage when I had it connected to an input.So I went to the 2007 jaycar catalog and looked at the specs cos the manual is long gone: No impedance rating even given!!Edit: I remembered where I left the book for the old meter. Input impedance is supposed to be 10 meg. Well is isn't 10 meg today. Something's amiss.+1 the OP. Hurry up Fluke and get here.
I gotta package people! - Page 1
Forum section: electronics / beginners

author: PerranOak
author_rank: Frequent Contributor
timestamp: July 18, 2019, 04:12:09 pm
content: Does anyone have/know of a "list" of all the various packages in which chips come?The best would be a PDF or something that has them all and simple details of dimension stats, etc. with a diagram for each.Cheers.

author: Jwillis
author_rank: Super Contributor
timestamp: July 19, 2019, 05:48:09 am
content: http://ww1.microchip.com/downloads/en/PackagingSpec/00000049BQ.pdfeasily Googled or have I misunderstood the question

author: forrestc
author_rank: Unknown
timestamp: July 19, 2019, 06:05:55 am
content: Quote from: PerranOak on July 18, 2019, 04:12:09 pmThe number of different types/varieties of packages which semiconductors come in is a lot larger than most people would think. Each manufacturer tends to have a different set of specs. Jedec does maintain a list of outlines in JEP95, but I haven't ever seen a copy.The best thing to do is to search on each manufacturer's website for packaging specifications.If you're looking for a general overview, wikipedia has a couple articles which list package types and show samples of them.

author: PerranOak
author_rank: Frequent Contributor
timestamp: July 19, 2019, 12:44:25 pm
content: That's great Jwillis, thanks. I guess I'm just a spanner at Googling!Thanks forrestc I just wanted a typical list that I could have to hand rather than searching each time.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 19, 2019, 12:46:38 pm
content: I was afraid for a moment you had to put people in packages.Tim
i have a ac speaker and i want to run it in my car - Page 1
Forum section: electronics / beginners

author: peterflax
author_rank: Newbie
timestamp: March 24, 2018, 01:34:52 pm
content: what do you guys recommend A dc to ac inverter or should i cut the wires of the transformer inside the speaker and connect them directly to the car power.

author: Brumby
author_rank: Unknown
timestamp: March 24, 2018, 02:17:53 pm
content: You have given less than 10% of the information necessary for anyone to even try and guess at an answer.Let's start with information about the "speaker" you are talking about. Make and model, pictures (well lit and in focus, please) and a couple of sentences describing what you see the problem is.We aren't mind readers - and while we could start throwing ideas around, they are going to be a lot more useful if you can give us some actual detail.

author: rdl
author_rank: Super Contributor
timestamp: March 24, 2018, 02:31:49 pm
content: Leave it in the house and go get something intended for automotive use.

author: Audioguru
author_rank: Super Contributor
timestamp: March 24, 2018, 04:48:35 pm
content: A car battery is "12V" but is actually about 14VDC. You and we have no idea about how much DC voltage the amplifier in your speaker uses. It might be 3VDC or might be 50VDC.If you feed the amplifier too much DC voltage then it blows up but if you feed it too little DC voltage then it will not work.How will you feed the speaker? Sound sources are stereo with two channels. You will need to combine the two channels with a circuit to feed the single speaker.
I have a couple of questions about this burglar alarm circuit - Page 1
Forum section: electronics / beginners

author: nullpoint
author_rank: Newbie
timestamp: May 13, 2015, 07:06:17 pm
content: This is a burglar-alarm circuit. There should always be a lightsource pointed to the LDR, and if the line of light is broken, the buzzer goes off.I have a couple of questions. How does the alarm stay on after the lightsource is back, and how does it reset after the switch is pressed?

author: Andy Watson
author_rank: Super Contributor
timestamp: May 13, 2015, 07:24:43 pm
content: T1 and T2 form a bistable. When T1 conducts, the voltage on its collector is low (and the buzzer sounds), T2 has no bias. When the switch is closed, T1 has no bias and stops conducting, it's collector voltage rises, cause in T2 to conduct. The voltage on T2's collector is now low - removing the bias for T1.

author: Delta
author_rank: Super Contributor
timestamp: May 14, 2015, 12:55:44 am
content: Is that an old symbol for NPN BJTs, or something weird and unique to a manufacturer?

author: Andy Watson
author_rank: Super Contributor
timestamp: May 14, 2015, 08:50:19 pm
content: Quote from: nullpoint on May 13, 2015, 07:06:17 pmI assume that you turn it on with SW1 closed. If SW1 is open, it could power-up in either state - it would be a matter of luck. It might be possible to force the state by bridging LED1 with a resistor - causing T2 to turn on first.Where did the circuit come from? Those are very old style transistor symbols!

author: Richard Head
author_rank: Frequent Contributor
timestamp: May 15, 2015, 10:14:21 am
content: I remember seeing those transistor symbols in the old Salora TV sets from the 70's. I think it may be a Scandanavian convention.

author: nullpoint
author_rank: Newbie
timestamp: May 15, 2015, 01:08:54 pm
content: Thanks!The circuit is from a relatively new exercise book. I've never seen those symbols before either.

author: nullpoint
author_rank: Newbie
timestamp: May 15, 2015, 01:10:25 pm
content: Quote from: Richard Head on May 15, 2015, 10:14:21 amThey are actually Scandinavian!
I have a problem form Amplifier voltage divide - Page 1
Forum section: electronics / beginners

author: mourad3d
author_rank: Newbie
timestamp: November 14, 2014, 09:42:59 pm
content: I have a problem form Amplifier voltage divideIs a problem that the ability to show me that the program Multisim itself is not showing me in the following accountsWhere the capacity of the planned 1.2 ml Watt, but the 8 Micro program show what the cause of itKnowing that the impedance of the biggest income impedance phase out Alsabakyhttp://upload.qariya.info/up2014/199054/F5DC850826F746D09E9B28FD9B719481.jpgThe File For Multisimhttp://www.4shared.com/file/Dmkajrgfce/Transistor15-11-2014.html?

author: RJFreeman
author_rank: Regular Contributor
timestamp: November 14, 2014, 10:28:16 pm
content: Not sure what you are asking, can you post a schematic?

author: mourad3d
author_rank: Newbie
timestamp: November 14, 2014, 11:18:42 pm
content: thank youThis amplifier circuit in the form of voltage divideI make some calculations to extract the circuit's capacity was 1.2 ml WattWhen the work program of simulation result of the ability did not show the exact reason for thisModify message

author: Zero999
author_rank: Super Contributor
timestamp: November 15, 2014, 07:05:05 pm
content: The link to the schematic doesn't work.Here's the schematic you posted this on a different forum.It's a basic common emitter amplifier.Are you asking for the calculations for the potential divider to bias the transistor properly?

author: mourad3d
author_rank: Newbie
timestamp: November 15, 2014, 09:34:40 pm
content: Ok the schematic Can you Download of the linkhttp://www.m3dmax.com/3d/Tran.zipI'm doing you the ability accounts, but the ability to Multisim program different Wayne error results

author: mourad3d
author_rank: Newbie
timestamp: November 16, 2014, 02:30:35 am
content: the schematic
I have a question with my RGB Header on my PC. - Page 1
Forum section: electronics / beginners

author: Whathefrench
author_rank: Newbie
timestamp: March 15, 2018, 08:59:25 am
content: Hi, I have a little project, let me explain:I want to control an rgb lamp, from an rgb header on my pc but wirelessly.I’m gonna use ATMega328P chips on both side, and flash an arduino bootloader on it. That way i can use arduino language.So, I have already design something for the lamp side.This ATmega328p, just basically receive data through RF, and just control the leds. If nothing is, receive for 30secs, the chip just run a small program, to light up the LEDs following a pattern.On the pc side, I haven't really done anything yet. How can I power the circuit from the rgb header, and recover the pwm signals from the header at the same time ?I know the rgb header for pc are common anode, because the header is [+12V,G,R,B]Thank you in advance for your answer! (Sorry, for my bad level of english, i'm not a native english speaker)