hybridfree/eevblog-posts huggingface dataset:
Negotiating Power with USB 3.1 - Page 1
Forum section: electronics / beginners

author: awwende
author_rank: Contributor
timestamp: December 18, 2015, 02:37:40 pm
content: Preface: I'm a beginner to USB power negotiation, but experienced circuit designer. Other forums have been critical of the idea of doing this, but I'm looking for advice on how to do it, not if I should do it (sorry if my frustrations come across as me being a dick).The newest USB standard, 3.1 offers a wide range of power output options:5V, 900mA (USB 3.0)5V, 2A12V, 5A20V, 5AExisting USB 2.0 power optionsHas anyone worked with USB 3.1 and negotiating power? I'd like to work on a project similar to Dave's USB PSU, but with more power output.Do I need an IC to do the power negotiation (if so, is there one that's readily available from digikey/mouser)?Or can I do the same thing as the old DIY Apple chargers where you use a resistor voltage divider to enable the full power output from the USB port?

author: miguelvp
author_rank: Super Contributor
timestamp: December 18, 2015, 07:45:55 pm
content: I have not done it, but I've seen videos from Cypress explaining details on how it works.Google: "cypress usb type c" or start at this page:http://www.cypress.com/products/usb-type-c-and-power-delivery
NEMA 14-50 Distro Box - Page 1
Forum section: electronics / beginners

author: tommygdawg
author_rank: Contributor
timestamp: June 06, 2016, 10:34:03 pm
content: Hey all,Curiosity strikes again! I've tried googling this but am having a hard time finding the right keywords to use. The question is simple, do any companies make distro boxes that take a NEMA 14-50 input? I'm trying to find a convenient way to plug into a stove outlet and power one or two big cinema lights or multiple smaller lights. I realize stoves take 220V AC, so if I'm plugging in 110V lights there'd have to be a transformer in the box as well. Seems like these types of devices must exist somewhere though?Thanks!- Tommy

author: sokoloff
author_rank: Super Contributor
timestamp: June 08, 2016, 12:55:00 am
content: A 14-50 is already center-tapped and grounded, meaning it has all four wires, Line 1, Line 2, Neutral, and Ground. You don't need a transformer to pull 120VAC; you use one of the Lines and the Neutral (and Ground if you want).For what you want, I'd look into a construction panel or a small sub-panel. You will want to be able to put a breaker in before running a 15A extension cord from a 14-50 plug (which itself will have an overcurrent device far higher than the 15A/20A extension cord, leaving you in a potentially unsafe situation). Use a subpanel or construction panel and you can get a breaker to protect the outlet-connected device wiring.

author: sokoloff
author_rank: Super Contributor
timestamp: June 08, 2016, 01:08:28 am
content: Here's one example of the construction power box I was talking about:https://www.ebarnett.com/Sku/2464302?cid=SHOP_Barnett_Over99_PP_1_ALL_C&CAWELAID=120259710000019350&CAGPSPN=pla&CAAGID=26759212846&CATCI=pla-167897769406&gclid=CjwKEAjw4dm6BRCQhtzl6Z6N4i0SJADFPu1nzZ9cCOVRyGm76bGdAQY84vPz3IGInqIoN4XTtcPHcBoCfy3w_wcBMany, many others are available. You could feed that with a whip from a 14-50P. Something like:http://www.amazon.com/Conntek-RL-40401-4-Feet-40-Amp-Range/dp/B00BHGXYUE?ie=UTF8&keywords=nema%2014-50%20cord&qid=1465348077&ref_=sr_1_2&sr=8-2

author: tommygdawg
author_rank: Contributor
timestamp: June 08, 2016, 05:57:06 pm
content: Thanks for the thoughts! Perhaps I should be more specific...I'm looking for something like this:http://www.discountplumbingoutlet.com/cep-construction-electrical-products-6503gu-30-amp-mini-portable-power-center/?gclid=Cj0KEQjwhN-6BRCJsePgxru9iIwBEiQAI8rq86bJ4qhqwlXIMb4G9bcmZTgTLUKHsHpgf0vvrftCozQaAg5i8P8HAQExcept the difference is, I'm looking for something that takes a 50 amp input, ie like what you get for a stove, so I can get a bit more juice into it. Do these exist?
Neon electronic power supply design resources - Page 1
Forum section: electronics / beginners

author: gfunk7390
author_rank: Newbie
timestamp: December 13, 2016, 10:12:21 pm
content: Hello all,I have been working with bending neon for the past couple of years and have become interested in learning more about how their power supplies are designed and built. So far, I have found some good insights by looking through patents, but have yet to find much by way of actual technical resources. I'm particularly interested in solid state power supplies and specialty power supplies (dimmable:http://www.t2-neonpower.com/PRODUCTS/NEON_SUPPLIES/midget_files/midget.html, scripting:http://ventextech.com/neon-power-supplies/12-volt-dc/) I'm wondering if anyone can point me in the right direction with regards to finding any resources on electronic neon power supplies (textbooks, educational resources, design manuals, etc.). If anyone has any information regarding schematics, theory, or design particularly behind the scripting transformers that would be amazing!Thanks,G
Neon lamp on analogic scope trigger pcb - Page 1
Forum section: electronics / beginners

author: gkmaia
author_rank: Frequent Contributor
timestamp: April 14, 2019, 08:18:57 pm
content: What are these neon lamps for when placed on a trigger board of an analog scope?

author: alsetalokin4017
author_rank: Super Contributor
timestamp: April 14, 2019, 08:26:27 pm
content: voltage regulation

author: tggzzz
author_rank: Super Contributor
timestamp: April 14, 2019, 08:47:48 pm
content: Show us the complete diagram, especially whatever the neons re connected to via P402.

author: Cliff Matthews
author_rank: Unknown
timestamp: April 15, 2019, 12:19:15 am
content: OP may find help here:https://www.eevblog.com/forum/testgear/tektronix-2246-no-beam!/msg314786/#msg314786(Tek's 2246 uses this limiter too)

author: gkmaia
author_rank: Frequent Contributor
timestamp: April 15, 2019, 02:03:21 am
content: Quote from: tggzzz on April 14, 2019, 08:47:48 pmThere you go!

author: Cliff Matthews
author_rank: Unknown
timestamp: April 15, 2019, 02:18:18 am
content: Same idea, maybe they copied Tek limiting that grid to ~130v. A lot more than just triggering going on there IMO.

author: floobydust
author_rank: Super Contributor
timestamp: April 15, 2019, 02:39:23 am
content: The two series-connected neon lamps form a gas discharge tube protecting the CRT and driver from any static or arc discharges.They go directly across the cathode-to-control grid of the CRT. Nothing to do with the trigger section. The two clamp diodes D407, D408 prevent any +ve CRT grid bias and the neons limit -ve grid bias to ~180VDC.They should never be glowing except for maybe a blip on power up/down.

author: gkmaia
author_rank: Frequent Contributor
timestamp: April 15, 2019, 03:29:21 am
content: Thanks for all the answers.What is right way to test these lamps and make sure they are in working condition?

author: tautech
author_rank: Super Contributor
timestamp: April 15, 2019, 04:31:54 am
content: Quote from: gkmaia on April 15, 2019, 03:29:21 amThey rarely are crook as they're only ON in an over-voltage event (read fault).Typically neons conduct ~90V.

author: tggzzz
author_rank: Super Contributor
timestamp: April 15, 2019, 06:59:11 am
content: Quote from: gkmaia on April 15, 2019, 02:03:21 amThat's more complete information, especially the scope type - other people might have specific experience of a particular scope type.That isn't the case here, but we can see the neons are a traditional way to protect the tube from excessive grid-cathode voltages. In functioning Tektronix scopes they flicker on/off for up to 10s after the power has been turned off.
Neon sigh transformer - Page 1
Forum section: electronics / beginners

author: Andrei917
author_rank: Newbie
timestamp: March 01, 2013, 11:26:17 pm
content: Hi! I just got a used neon sigh transformer (nst) from a "junkyard". It is supposed to be 10kv 50mA, but the electric arcs are too small, like 1/3" os less (8mm). I can't really measure it with a multimeter, so I assumed the sparks are to small for 10kv. I think that because I just watched a video about nst transformer, I think it was 10kv, 20mA, and the sparks were bigggg, like 2 inches. Oh please don't play with this if you don't understand the risks, these things are letal...

author: rsjsouza
author_rank: Super Contributor
timestamp: March 02, 2013, 12:32:31 am
content: It is possible that your transformer is designed for a higher primary voltage (220V)? If you have a variac connected to the primary, this will allow you measure the voltage ratio of the transformer by applying a small input voltage and measuring the output voltage with a regular DMM.Also, the distance of the arc will depend on a series of factors, but the most significant would be the air humidity and the shape of the probes that are creating the arc.I have a 9kV neon transformer that creates sparks around 10mm when using round probes...

author: amyk
author_rank: Super Contributor
timestamp: March 02, 2013, 05:11:13 am
content: The dielectric strength of air is around 3kV/mm. If you get 8mm sparks that's ~24kV already.The open-circuit voltage will likely be higher, but you won't get 2" (~50mm) spark unless it's around 150kV.(This is assuming you are doing this in a standard dry atmosphere.)

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 02, 2013, 09:40:31 am
content: That sounds about right for a 10kv NST

author: Psi
author_rank: Super Contributor
timestamp: March 02, 2013, 11:27:24 am
content: 8mm sounds about the same as my 12kv 30ma transformer, once the arc forms thought you can drag it out 3-4cm.A few things i can think of...- Are you using both sides of the NST?- Have you checked both sides are actually working. You should get smaller arcs from each side to the center ground.Its common for one side of an NST to die and when that happens they only output half the voltage.Be safe.
Neon tube from Sega Game gear  - Page 1
Forum section: electronics / beginners

author: crt_cowboy
author_rank: Regular Contributor
timestamp: March 04, 2024, 12:01:59 pm
content: Hello,As a small pet project, I would like to make light with a small neon tube harvested from a Sega Game Gear console.Below the circuit from the console. Basically there is an oscillating circuit connected to a transformer.From the measurements I made in the console before removing the neon tube, it gets 30KHz 198 vpp. At the startup, it goes higher, around 290vpp.If I connect the neon to a 220v 50Hz power source (with a resistor as ballast), nothing happens.Any recommendations on how to make this work would be greatly appreciated.Thanks

author: Zero999
author_rank: Super Contributor
timestamp: March 04, 2024, 12:22:58 pm
content: It isn't a neon tube, but a cold cathode tube. It needs a high voltage, on the order of 1kV to start, which then drops down to a much lower voltage.I would put the console back together and sell it and buy a suitable cold cathode tube. Classic consoles go for reasonable money and even if it doesn't work you'll quite likely get more than a new cold cathode tube and driver will cost you.

author: crt_cowboy
author_rank: Regular Contributor
timestamp: March 04, 2024, 12:31:50 pm
content: The LCD was dead so I replaced it with a modern screen with backlight. I was wondering if I could experiment with the tube but looks like I would need a specific power supply

author: Zero999
author_rank: Super Contributor
timestamp: March 04, 2024, 01:52:21 pm
content: The circuit attached to your original post is a Baxandall or Resonant Royer conveter. A type of oscillator which uses the transformer as a resonant component.https://en.wikipedia.org/wiki/Royer_oscillator#Sinewave_Oscillator_(Baxandall,_aka_%22Resonant_Royer%22_vs_Original_Royer)Although the circuit is simple, it needs a specially designed transformer. You can buy it ready made. Search for CCFL inverter.
Neophyte with Tec 465 problem - Page 1
Forum section: electronics / beginners

author: Wire Nut
author_rank: Newbie
timestamp: June 30, 2014, 04:28:32 pm
content: I recently got a Tec 465 scope in pretty good shape, I tried the trace location and it did not show up. I got advice on this forum on how to take the cover off and much to my distress the rattling I heard inside was two broken caps (see photo) they seem to say 1Z over 12v over C80 I can't figure what the value of these are. I do not have access to a repair manual and could use some advice. Of course I want to fix the obvious things first- so I am starting here.

author: katzohki
author_rank: Frequent Contributor
timestamp: June 30, 2014, 04:32:32 pm
content: Yes, start with those of course. Here are the service manuals:http://www.ko4bb.com/manuals/index.php?dir=Tektronix/Tektronix_-_465_Oscilloscope/Tektronix-465_Service_Manual

author: Wire Nut
author_rank: Newbie
timestamp: June 30, 2014, 04:55:11 pm
content: Thanks so much for the manuals! I did not see the parts that I am looking for... I am used to working with record players and they have almost always exploded views of everything so first I find the part by sight, then locate it on the schematic. Could someone please help me identify those broken parts, or tell me what page the parts are on in the service manual?I figured if I got a scope and could use it, it could help me fix turntables.

author: katzohki
author_rank: Frequent Contributor
timestamp: June 30, 2014, 05:19:44 pm
content: I'm not great at identifying ceramic disc caps. Try looking at the other side.

author: Wire Nut
author_rank: Newbie
timestamp: June 30, 2014, 05:30:29 pm
content: The back side is blank on both... bummer

author: PA0PBZ
author_rank: Super Contributor
timestamp: June 30, 2014, 06:05:31 pm
content: Must be 0.1u (=100n) / 12volt.
NESS D8/D16 ALARM PCB Problem - Page 1
Forum section: electronics / beginners

author: Adrian Chick
author_rank: Newbie
timestamp: May 03, 2021, 05:00:01 am
content: We Recently moved into a house that has a NESS D8/D16 Alarm system, which is completely dead. I called an alarm technician to come and have a look. He replaced the backup battery, because it was only giving 4.2VDC and should be giving at least 12VDC. The alarm powered on and there was a flashing led on the main PCB, All Good!. However when he disconnected the backup battery, the system died again, despite there being 17VAC on the board at the terminal point. Obviously if I run it on just the battery eventually it will drain and I will be back to square one.I'm no Electronics person, but I am assuming the this must be something to do with the power input side of the board. There appears to be no components showing as being burnt out.I watched the video that had previously been posted that showed someone with a thorough knowledge of this NESS D8 system, so I am hoping someone in your great forum can help.The Technician left with his good battery and will be sending me a quote for a full system replacement!Any Help is greatly appreciated.Thanks. Adrian.

author: Valden
author_rank: Regular Contributor
timestamp: June 20, 2025, 09:10:06 am
content: Hello Adrian. Did you get the problem with your Ness D8/D16 alarm system sorted out?In case anyone finds this thread while looking for clues, for a similar problem that Adrian has described I was able to bring a Ness D8 alarm system back to life by replacing the five surface mount electrolytic capacitors on the PCB. Three were dead. These were making the Fujitsu microcontroller and the Fairchild EEPROM look dodgy, but they were in fact just fine. So, an easy fix for anyone who's handy with a soldering iron. Our Ness D8 that was only half working is now firing on all cylinders.
Netgear router silkscreen designator 'B' - Page 1
Forum section: electronics / beginners

author: Sjokolade
author_rank: Regular Contributor
timestamp: October 26, 2021, 11:17:28 pm
content: HiI crossflashed a Netgear router to a bigger model and I'm going to solder in an usb port that this smaller model did not have, there are 3 components missing and 2 of them has silkscreen designator B2 and B3 - anyone know what this components are supposed to be ?The missing cap C195 I found out is a 16V 100 microfarad.

author: ataradov
author_rank: Super Contributor
timestamp: October 26, 2021, 11:41:11 pm
content: They are ferrite beads. You can just put 0 Ohm resistors or jumpers there.
Network cable tester - Page 1
Forum section: electronics / beginners

author: mike_mike
author_rank: Super Contributor
timestamp: February 13, 2022, 12:56:05 pm
content: Hello! I would like to build a network cable tester based on 555, 4017, led's and a few more components. I would like to test UTP, STP and FTP Cat5e and Cat6 cables, which uses shielded RJ45 and unshielded RJ45 connectors.I want to mention that I need led's on both emitter and receiver of the tester, to see if the wires are swapped.This is the first schematic that I found:http://www.frankshospitalworkshop.com/electronics/diy-lan_cable_tester.html- I used a 9V battery, and I replaced the 47R resistors with 470R resistors.This is the second schematic:1. Transmitter:https://danolteanu.000webhostapp.com/testerrj45.gif2. Receiver:https://danolteanu.000webhostapp.com/receiverrj45.gifI built the first schematic, and it is working, but then I needed led on the receiver part, and then I built the receiver from the second schematic (2).I wanted to know if there is possible to make some simple improvements to this schematic ?

author: danolteanu
author_rank: Newbie
timestamp: December 10, 2023, 09:30:54 pm
content: Hi,I've designed the second schematic.Build the transmitter and the recevier and it works perfect, no improvements necesarry.BR/Daniel

author: liaifat85
author_rank: Regular Contributor
timestamp: December 12, 2023, 03:58:20 pm
content: Oh.The circuit designer himself is here! I believe, now you'll get the most authentic help regarding your network cable tester.

author: madires
author_rank: Super Contributor
timestamp: December 12, 2023, 04:23:18 pm
content: Looks very similar to the inexpensive 'LAN testers' sold for 10 bucks (the design is 20+ years old). They are great for checking continuity.

author: SeanB
author_rank: Super Contributor
timestamp: December 12, 2023, 04:52:54 pm
content: Yes, the only improvement would be to have a small 8R speaker in the Vdd of the 4017, so that each transition provides a small click, and also if the connections are intermittent you will get noise out of the speaker, telling you of an intermittent joint in the cable.Also add a 1000uF 25V capacitor across the supply pins of the 555 timer, which will help with stability as the 9V battery ages.
neutral to ground noise? - Page 1
Forum section: electronics / beginners

author: Al3579
author_rank: Newbie
timestamp: September 03, 2019, 12:54:29 am
content: This blue trace is neutral to ground reference and the yellow is line to ground. It is present throughout the whole house. I'm thinking about flipping breakers to see if its a device in the house dumping it on the neutral. Sometimes I've heard heard audible tones at about 1khz. The pulse width of the noise is about 1.85ms. I also recorded the ground to neutral noise directly it 9th harmonic 60hz noise which is 540hz.When it actually becomes audible its comes out as a 1khz tone. Maybe I'm just worrying too much!

author: Twistedsnail
author_rank: Contributor
timestamp: September 03, 2019, 01:10:34 am
content: Got any dodgy lamp dimmers or badly made LED dimmers running?

author: Al3579
author_rank: Newbie
timestamp: September 03, 2019, 01:56:01 am
content: yeah I'm going to the panel and start flipping breakers see if I can isolate it to a circuit I'll report back. Thanks!

author: David Hess
author_rank: Super Contributor
timestamp: September 03, 2019, 03:46:27 am
content: That is hardly unusual. Neutral and ground are bonded together at the service entrance and since neutral carries all of the return current, it deviates from ground depending on the impedance between them.That waveform comes from the harmonic current into a rectifier-capacitor filter commonly found on a switching power supply that lacks power factor correction.

author: Al3579
author_rank: Newbie
timestamp: September 03, 2019, 07:26:17 pm
content: Yeah I went to the panel turned off all the breakers except the one powering the oscilloscope still there just at a diminished level depending on how far the circuit is from the panel. I turned off all the breakers and powered the oscilloscope straight from the lugs of the panel and since neutral and ground are tied together at the panel I thought I wouldn't pick up a thing. I didn't float the ground on the oscilloscope just fyi. Attached is the measurement with about 10ft of extension cord from panel without anything on in the house. I'm thinking it a measurement error or some kind of signal from the service meter or stray current. I started this investigation because I've had 2 microwaves that messed up in a relatively short period of time and some fans that I thought died prematurely and a direct box that wasn't connected to anything short out. The direct box I had was used to take high impedance unbalanced signals and convert them to low impedance balanced signal for impedance matching into a op amp. It was a simple passive design and nothing more than a transformer with adjustable pad and ground lift.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 03, 2019, 07:59:14 pm
content: Neutral voltage drop, and induced ground voltage, comes from current flow. So, there's a lot of current drawn on those peaks, and not as much inbetween.This is typical for rectified mains -- SMPS and such.Tim
Never seen this component before, what is it? - Page 1
Forum section: electronics / beginners

author: WyverntekGameRepairs
author_rank: Regular Contributor
timestamp: May 10, 2020, 05:41:21 pm
content: I was salvaging old components from an old audio amplifier that no longer worked, and I came across this little guy. Google has failed me, so I’m hoping you guys can tell me what it is. Is it a capacitor? Is it a weird diode? Rectifier perhaps (tho highly unlikely as voltage rectifiers have 3 pins, input, common, and output...)?Thanks!

author: Stray Electron
author_rank: Super Contributor
timestamp: May 10, 2020, 05:45:06 pm
content: 5.5 volt 47 picofarad (47 x 10**3 micro micro farad) cap?

author: ggchab
author_rank: Frequent Contributor
timestamp: May 10, 2020, 05:45:27 pm
content: Plenty of pictures on InternetEx.:https://shopee.ph/2pcs-Japan-original-NEC-super-Farad-capacitor-5.5V-0.047F-473-square-capacitor-FMROH473ZF-i.163724074.2511028432

author: Dave
author_rank: Super Contributor
timestamp: May 10, 2020, 05:46:05 pm
content: A 5.5V 47mF supercap.Datasheet (page 22)

author: WyverntekGameRepairs
author_rank: Regular Contributor
timestamp: May 10, 2020, 06:11:38 pm
content: Welp, guess I was looking at the wrong thing.Thanks everyone!Also, I should’ve guessed it was a super capacitor. The amp had a clock, and it would’ve needed a backup for the clock IC.
New (to me) HP3455a problem - Page 1
Forum section: electronics / beginners

author: Jeff L
author_rank: Contributor
timestamp: May 30, 2018, 02:25:34 am
content: Hi, Just received my HP 3455a 2 days ago. Was working fine, now won't switch to "ohms" ,also won't do the"test" of all the LEDs like it did when I first got it. Actually, quite a few of the functions don't work now. I'mno Tesla, but I do know my way around a voltmeter and a 'scope.Any idea where to start? I have downloaded the owners and maintenance manual.Thanks, Jeff

author: Testtech
author_rank: Regular Contributor
timestamp: May 30, 2018, 04:06:46 pm
content: Stuck button?

author: pelule
author_rank: Frequent Contributor
timestamp: May 30, 2018, 05:58:24 pm
content: Another potential cause - during the shipemt the plug-in boards have lost the connection.Solution: remove top cover & internal analog top cover and re-plug the boards./PeLuLe

author: Jeff L
author_rank: Contributor
timestamp: May 30, 2018, 11:31:02 pm
content: Re-seated the small top board and sprayed with De-Oxit ---Problem Solved!!!
New 2000W autotransformer, should I disconnect mains earth pin ? - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: June 25, 2018, 08:52:20 pm
content: I got a TDGC2-2k from ebay, 0-130V up to 2000VA and I very pleased. However I want to use it as an isolation transformer too, for use on small stuff like computer PSU repair.So should I disconnect the mains earth wire from the entire unit or just from the output plug ?

author: wraper
author_rank: Unknown
timestamp: June 25, 2018, 08:55:07 pm
content: Why do you think it isolates anything? It should have only one winding, no secondary.

author: IanB
author_rank: Super Contributor
timestamp: June 25, 2018, 08:57:35 pm
content: As per the previous poster. A variac is not an isolation transformer and cannot be used as such.However, it can be useful to bring up the voltage slowly on an untested device to check for any malfunctions before applying the full mains voltage.

author: Zero999
author_rank: Super Contributor
timestamp: June 25, 2018, 10:36:20 pm
content: No, don't remove the earth pin.If you need to ask such questions, you really shouldn't be playing with this. Please read up more on the different types of transformers, including isolating and auto-transformers, before going any further. Failure to do so, could result in serious injury or death.

author: lordvader88
author_rank: Frequent Contributor
timestamp: June 26, 2018, 12:22:12 am
content: Quote from: IanB on June 25, 2018, 08:57:35 pmWell they should call it an auto-inductor since there's only 1 coil. I thought it was a transformer, especially for the price.

author: wraper
author_rank: Unknown
timestamp: June 26, 2018, 12:42:32 am
content: Quote from: lordvader88 on June 26, 2018, 12:22:12 amIt's a transformer, just with single winding acting like both primary and secondary. And "inductor" is not limited to a single coil.

author: Nusa
author_rank: Super Contributor
timestamp: June 26, 2018, 12:44:18 am
content: Quote from: lordvader88 on June 26, 2018, 12:22:12 amIt's more a case of you not knowing the terminology. The "auto" in "autotransformer" tells you it's a particular type of transformer having only one winding acting in both the primary and secondary roles.

author: innkeeper
author_rank: Unknown
timestamp: June 26, 2018, 01:18:43 am
content: Quote from: lordvader88 on June 25, 2018, 08:52:20 pmNO, NETHER ... it is not an isolation transformer!watch this all the way through....

author: SG-1
author_rank: Regular Contributor
timestamp: June 26, 2018, 02:25:55 am
content: The most exciting part is that a fault on the secondary side is a fault on the primary side, since they are one in the same.All you need now is an isolation transformer connected to the output of your autotransformer & your set.
New Aglient 1242b User/DMM, is this normal screen to do? - Page 1
Forum section: electronics / beginners

author: xclayx
author_rank: Newbie
timestamp: October 23, 2011, 04:11:49 am
content: Hi,Just received my 1242b and I've used it a few times, never dropped, knocked or otherwise. I noticed today as I was playing with the backlight button. When the screen is lit up if you gently swipe your finger accrossed the bottom of the screen or from bottom left to top left theres very fine spiderweb that shows along the bottom following the edge and up the left side. I'm worried that the screen/glass is cracked, but I can't actually see any cracks. Normal? or not.no, I haven't taken it apart yet.Thoughts? Anyone with a 1242b or similar confirm?Thanks!

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 23, 2011, 09:40:29 am
content: Picture !! The words are poor to show what happens.

author: DaveW
author_rank: Frequent Contributor
timestamp: October 23, 2011, 06:48:04 pm
content: Quote from: xclayx on October 23, 2011, 04:11:49 amJust tried it with mine-I can't replicate anything that looks like your description....

author: orbiter
author_rank: Frequent Contributor
timestamp: October 29, 2011, 08:14:52 pm
content: Quote from: xclayx on October 23, 2011, 04:11:49 amSomething doesn't sound right. I'd RMA it for a replacement.
New ATTEN 1102cal+ - Page 1
Forum section: electronics / beginners

author: kgavionics
author_rank: Regular Contributor
timestamp: June 03, 2012, 11:49:15 pm
content: hii've bought my first oscilloscope ATTEN 1102cal+ and every thing is all right exept i dont know how to remove the 60hz sinwave ( it shows a sin wave when there's no signal)thank you in advance

author: w2aew
author_rank: Super Contributor
timestamp: June 04, 2012, 12:19:30 am
content: Quote from: kgavionics on June 03, 2012, 11:49:15 pmIs this occurring with nothing connected to the input connector, or do you have wires hanging on the input? If there is nothing connected to the input connector at all, then it sounds like a fault. If you have a wire connected (and connected to nothing at the other end), it sounds like normal 60Hz pick-up from the mains supply.

author: kgavionics
author_rank: Regular Contributor
timestamp: June 04, 2012, 01:56:31 am
content: Quote from: w2aew on June 04, 2012, 12:19:30 amthank you for replyyou are right, this situation occurs when i plug only the probe without ground.Is there a possiblity to remove this option because is very confusing for me?thank you again

author: Monkeh
author_rank: Super Contributor
timestamp: June 04, 2012, 02:14:40 am
content: Quote from: kgavionics on June 04, 2012, 01:56:31 amYes, connect your ground lead.What on earth do you expect to happen if you have a meter or so of wire hanging around?

author: w2aew
author_rank: Super Contributor
timestamp: June 04, 2012, 05:27:12 am
content: Quote from: kgavionics on June 04, 2012, 01:56:31 amIt isn't an option - it's doing exactly the correct thing. The unconnected wire on the input is acting as an antenna, and it's picking up the 60Hz field from the air. Are you using a proper probe, or just unshielded wires? You may want to review my "Probes" video - go to YouTube.com/w2aew - lots of basic oscilloscope videos there, including one on the basics of probes.

author: kgavionics
author_rank: Regular Contributor
timestamp: June 04, 2012, 11:02:59 pm
content: thank you guys now every thing is clear for me
New Benchtop PSU not displaying current ... - Page 1
Forum section: electronics / beginners

author: Kilroywashere
author_rank: Regular Contributor
timestamp: November 24, 2017, 01:18:07 am
content: Hey, I just got the STP3005H SKYTOP POWER supply . I turn it on and it does not display current i turn the pots and nothing no 0 to 5 amps adjust..... However if i hook up a battery 3.4 v i can adjust it lower till it shuts the thing down ( not off just zeros it out)Is this normal in a cheap power supply???Do you need more info or some pics?Is this damn thing broken? or do i not know how to use it?

author: Mr.B
author_rank: Unknown
timestamp: November 24, 2017, 01:41:26 am
content: I cannot seem to find an instruction manual anywhere on the interwebs for it.However, usually cheap supplies such as this require the following:Set the voltage to your desired working voltage. e.g. 5.0VTurn the current knob(s) down to zero.Short out the pos and neg output of the supply.Increase the current knob(s) until the desired current limit is displayed. e.g. 0.1ARemove the short across the output.The power supply should now supply 5Vdc up until it current limits at 100mA (0.1A)While supplying the 5Vdc it will show you how much current is being drawn.

author: jcw0752
author_rank: Contributor
timestamp: November 24, 2017, 04:53:40 am
content: Hi,You do not say anything about adding a load to the output. If you have just turned on the power supply without a load you will be able to adjust the voltage but since there is no load the current will not adjust and will continue to show zero regardless of where the current adjustment is set.John

author: Brumby
author_rank: Unknown
timestamp: November 24, 2017, 05:53:38 am
content: It would seem this supply only displays actual values - and not "set" values.For volts, this is easy - because voltage does not depend on a load (unless it is excessive) - so you can set the volts with the supply and nothing else.For current - not so. You will need a load of some sort so that there is an actual current flow that can be displayed.Quote from: jcw0752 on November 24, 2017, 04:53:40 amJust so.If you want to be able to pre-set the current limit, then this is how:Quote from: Mr.B on November 24, 2017, 01:41:26 am

author: mcinque
author_rank: Unknown
timestamp: November 24, 2017, 07:09:45 pm
content: It's a normal behavior for "non programmable" PSUs, you can always see the voltage but you will see the current only with a load connected.As Mr.B said, in that PSUs you should set your desired current by shorting the leads and adjusting the maximum current value or leave it to the maximum if you don't want a specific current limiting.It is not broken, you need just a little bit of practice like everyone approaching something new.
New Brymen Test Leads - Question on Tip Insulation - Page 1
Forum section: electronics / beginners

author: LanceK
author_rank: Newbie
timestamp: November 13, 2020, 04:23:03 am
content: I just bought a new Brymen BM869s Multimeter and there appears to be insulation (or protective cap of some sort) on the test lead (right angle side that goes into the multimeter).This is my first higher end multimeter and I haven't seen this type of insulation on a set of test leads. Should I remove these caps or leave them?Image below:

author: gcewing
author_rank: Regular Contributor
timestamp: November 13, 2020, 05:43:09 am
content: Leave them on! Their purpose is to provide extra insulation against high voltages. There should be a matching groove around the socket on the meter to accept them.

author: LanceK
author_rank: Newbie
timestamp: November 14, 2020, 04:11:09 am
content: Thank you gcewing! You're correct, there is a matching groove around the socket on the meter. Appreciate you clarifying that for me.

author: wraper
author_rank: Unknown
timestamp: November 14, 2020, 04:25:34 am
content: It's a protection in case when leads are accidentally left unplugged or not fully plugged. Nothing to remove there.

author: radiolistener
author_rank: Super Contributor
timestamp: November 14, 2020, 06:16:41 am
content: my brymen probes don't have such plastic caps
New DMM... Malfunction or Normal? - Page 1
Forum section: electronics / beginners

author: HiGhGuY
author_rank: Newbie
timestamp: November 03, 2012, 11:52:40 am
content: Hi, I just got a new DMM, the Amprobe AM-240. When I turn it on to "V" with the test leads in, the voltage is constantly fluctuating. When the dial is turned to VAC its fluctuates roughly between 20-50mV and when the dial is on VDC it fluctuates roughly between 100-500mVIs this normal or did I receive a defective product? other DMMs I have used have never done this, they have just stayed at 0 until connected to a voltage source. Then again, the ones I have used before didn't measure down to mV... only VI would appreciate any help, thanks.

author: AndyC_772
author_rank: Super Contributor
timestamp: November 03, 2012, 12:00:04 pm
content: What happens if you short the probes together, does it read close to zero then?

author: HiGhGuY
author_rank: Newbie
timestamp: November 03, 2012, 01:43:39 pm
content: yes, when touching the probes, in VAC i get down to .2mV and in VDC 0

author: Simon
author_rank: Unknown
timestamp: November 03, 2012, 04:12:45 pm
content: pretty much normal, the input impedance is very high (10+Mohms) and the leads act as aerials picking up mains power that emanates a magnetic field all around you. Same happens on oscilloscopes, you will see an almost perfect 50Hz sine wave if you just wave the probes in the air. i remember being on the floor playing with my rigol and my dad walked past, the whole wave shifted up and down as he passed as his movement upset the magnetic field and effectively modulated it at a very low frequency

author: G7PSK
author_rank: Super Contributor
timestamp: November 04, 2012, 04:15:20 pm
content: Normal mine reads 2.4 mv ac and 6mv valts dc without any probes even its just picking up stray voltage zeros as soon as the leads are shorted, often wondered if those stray voltages are added to whatever voltage is being measured.

author: Simon
author_rank: Unknown
timestamp: November 04, 2012, 04:17:29 pm
content: no, that voltage is picked up due to the sensitivity of the meter, as soon as you connect it to something that will have a low impedence by comparison so it will just go away

author: Unknown
author_rank: Unknown
timestamp: November 04, 2012, 05:03:19 pm
content: True RMS meters are expected to have a slight offset with the inputs shorted. A true RMS converter has poor linearity near 0V, so the manufacturers choose to spec the meter only from 5% of full scale and up, rather than adjusting for zero offset and compromising accuracy at higher voltages. Seethis Keithley documentfor more information.
New Educational Videos - Page 1
Forum section: electronics / beginners

author: Rich@RohdeScopesUSA
author_rank: Frequent Contributor
timestamp: March 11, 2022, 04:20:29 pm
content: Hi Folks - it's been a while since I posted an update on this so I thought I'd start a new thread. In our T&M Fundamentals series, we now have 104 different videos available on YouTube, with new videos coming weekly. Everything from "Understanding Smith Charts" to "Understanding LISNs" to "What is RF?" to "Understanding UARTs".https://youtube.com/playlist?list=PLKxVoO5jUTlvsVtDcqrVn0ybqBVlLj2z8If you have a request, please let me know as well!-Rich
New Fluke 101 meter showing readings when not connected - Page 1
Forum section: electronics / beginners

author: makerman
author_rank: Regular Contributor
timestamp: January 28, 2019, 11:58:00 am
content: I managed to blow my multimeter the other day so ordered my first fluke (101), powered it on and when not measuring anything it's showing anywhere between 6-20 mA then slowly drops down. The uni-t meter and other cheapies i have don't do this, should i be worried ?

author: KermitTheFrogg
author_rank: Contributor
timestamp: January 28, 2019, 01:10:09 pm
content: Yoooo I don't think it is that bad. Some brand new multimeters aren't calibrated or maybe it is malfunctioning. Do you still have warranty?

author: Mr. Scram
author_rank: Super Contributor
timestamp: January 28, 2019, 01:21:03 pm
content: Both the Fluke 87V and Fluke 179 here do that, although they start at an even higher count. The Fluke 179 is only a few months old. I'd say it's expected behaviour.

author: makerman
author_rank: Regular Contributor
timestamp: January 28, 2019, 02:19:09 pm
content: Thanks for replies, it's measuring fine so i'll stick with it.

author: ender4171
author_rank: Contributor
timestamp: February 01, 2019, 03:49:30 pm
content: All of my Flukes do this. Try shorting the leads together. If it drops to 0.00 immediately, you have nothing to worry about. It's just stray inductance from the environment. I think cheaper meters are either just not sensitive to pick up EMI, or they use some sort of "zero-ing" circuit to discourage the behavior since a regular Joe would probably think it means the meter is broken.

author: Mr. Scram
author_rank: Super Contributor
timestamp: February 01, 2019, 04:12:08 pm
content: Quote from: ender4171 on February 01, 2019, 03:49:30 pmI think it's the latter. There have been instances of cheap meters "cheating" on their readings described on these forums. Instead of true linearity they seem to fix it in the firmware.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 01, 2019, 04:49:05 pm
content: Quote from: makerman on January 28, 2019, 11:58:00 amThat's crazy!! The meter is for sure bad as the Fluke 101 has no current measurement and can't display mA at all! Something must really be screwed up.
New guy trying to fix an old Tek scope. - Page 1
Forum section: electronics / beginners

author: anti-matt-er
author_rank: Newbie
timestamp: September 13, 2013, 05:32:15 pm
content: Hi everybody! I've been watching Dave's blog for over a year now and I've been inspired to try my hand at a a repair. I found an old Tektronix 442 scope near me for $25 and thought it would be a good choice for a first scope, provided I can get it to work again. I have a Fluke 87 III to measure with, but I don't have a hv probe right now (I could get one if needed).So here's the problem: I'm getting a pilot light but no image on the screen. All the outputs on the power supply board are good but the 1/16th amp fuse (F722) is blown. When I measure the current through across the fuse terminals I'm seeing 170ma and rising. When I left this on for a min several of the transistors got hot but I saw resistor 458 get extremely hot (glowing). I couldn't find any of the transformer coils shorted. Any suggestions on what could be wrong? I am not afraid of replacing parts and I'm not too bad at soldering, but I don't want to just throw parts at it. Is the resistor bad? It looks like the resistance has lowered.http://www.box.net/shared/0jn2bd5njp

author: dds
author_rank: Contributor
timestamp: September 13, 2013, 06:04:18 pm
content: http://groups.yahoo.com/neo/groups/TekScopes/infoThere's dedicated yahoo group for Tektronix scopes, maybe they can shed more light.

author: Unknown
author_rank: Unknown
timestamp: September 13, 2013, 08:23:32 pm
content: I second the recommendation for the TekScopes list.My guess would be that it's one of the components in the HV circuit, downstream of R458, that's causing excess current draw. Searching the TekScopes archives (although the search has been a bit temperamental since Y! introduced the new interface) should also give some helpful hints on troubleshooting HV circuits like this.

author: anti-matt-er
author_rank: Newbie
timestamp: September 14, 2013, 09:55:22 pm
content: Thank you for the suggestion. I have posted the question there as well. I'll continue to check here in case anyone has any other ideas and I'll reply if I find a solution.
New here! - Page 1
Forum section: electronics / beginners

author: The_PCB_Guy
author_rank: Regular Contributor
timestamp: March 24, 2013, 02:00:18 am
content: Good evening folks!I've been watching the EEVblog on youtube for some time now and decided it was high time I join the forum. Just wanted to introduce myself, but I'm not seeing an "off topic" forum, so hopefully I'm posting this in the right placeI am originally from a small town called Thetford, in Vermont, USA. I studied EET at Wentworth Institute of Technology in Boston, MA.I've been playing with electronics since I was 6 years old, and working with them officially since I was 12. Over the past couple of years I've moved more toward schematic and PCB design/layout and have had several of my PCBs manufactured. I've decided that PCB design is really what I'd like to do for my career. I've learned a lot from this blog and look forward to learning even more, as well as maybe even helping out a few people here and thereThanks to the admins for such a great blog! I look forward to becoming a regular here!Best wishes,Matt,The_PCB_Guy

author: Radio Tech
author_rank: Frequent Contributor
timestamp: March 24, 2013, 02:04:01 am
content: Hi and welcome. This is a great place. Sort of new to posting here myself.
New Here Component Selection  - Page 1
Forum section: electronics / beginners

author: DDCE88
author_rank: Newbie
timestamp: September 17, 2019, 02:03:30 am
content: Computer Engineering student here out of UNC Charlotte.We are working on our junior design project. Its a 300W DC to AC power inverter.I have the actual inverter stage designed and drafted up in LTspice. But now I'm in the stage where I'm looking to purchase parts for the device. I'm having trouble making a selections for some of the components specifically the inductors. I see about 35Arms going through my filter inductors, but am unable to find an inductor at the inductace and current rating, I see in the simulation on mouser or digikey.Included is my sim file.The spice model for the mosfet driver is included in the file it self.I am also including the PWL files used to simulat the PWM going into the mosfet driver.5V_10k_PWM_HIP_1S.txt goes to MC_PWM_HIGHSIDE and MC_PWM_HIGHSIDE15V_10k_PWM_LOWP_1S.txt goes to MC_PWM_LOWSIDE and MC_PWM_LOWSIDE1I know to many this should seem pretty obvious. I just don't want to drop a ton of money on this only to watch it blow up in my face.Thanks,Dan.

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: September 17, 2019, 02:31:49 am
content: Look out for power transformers with that current rating. One leg of the transformer can be used as an inductor. Most of the datasheets will also specify the inductance of the transformer winding.

author: Circlotron
author_rank: Super Contributor
timestamp: September 17, 2019, 02:34:34 am
content: Quote from: EEEnthusiast on September 17, 2019, 02:31:49 amIf there is DC going through the winding then a transformer will almost certainly saturate. Not a good solution if it doesn't have a gapped core.
New here, HI!!!!!! - Page 1
Forum section: electronics / beginners

author: biotron345
author_rank: Contributor
timestamp: November 30, 2015, 11:05:14 pm
content: Hello everyone!New to this forum. Although I've been interested in electronics since I was about 10 years old I've only really been seriously 'doing' electronics for around 10 years. I'm mainly interested in audio electronics (synths, amps etc.) and built a few lo-fi synths like Lunetta's, done lots of circuit bending and more recently building eurorack format modules. This said I have lots of gaps in my knowledgeSo hello everyone!!!!

author: orbiter
author_rank: Frequent Contributor
timestamp: November 30, 2015, 11:20:53 pm
content: Welcome to the forums friend.

author: crispy_tofu
author_rank: Super Contributor
timestamp: November 30, 2015, 11:25:51 pm
content: Welcome to the forum.
New Instructable for review: How To Use A Chip Vendor Op-Amp Model In Ltspice - Page 1
Forum section: electronics / beginners

author: RonFred2
author_rank: Contributor
timestamp: June 12, 2018, 03:52:52 pm
content: I am working on simulating the EEVBlog uCurrent schematic: Converting nA, pA, uA to millivolts. To get this simulation underway I needed to include Macromodels for the LMV321 and the MAX4239 op-amps. I went through a lot of Q/A with much friendly help from Yahoo's LTspice user group. After getting through my learning curve, I decided to write a "how to" on the topic...How To Use A Chip Vendor Op-Amp Model In Ltspicehttps://www.instructables.com/id/How-to-Use-a-Chip-Vendor-Op-Amp-Model-in-LTSpice/It's my first "Instructable" and I am still self learning electronics with EEVblog (and other's) help. Let me know if you have any suggestions to improve the tutorial.
New Member - Page 1
Forum section: electronics / beginners

author: ericaalex
author_rank: Newbie
timestamp: December 10, 2020, 10:50:24 am
content: Hello EveryoneI am new member in this forum.

author: JacobManson
author_rank: Newbie
timestamp: December 10, 2020, 10:58:00 am
content: Hello everyone, I am new to this forum, I am 22 years old and I am fond of programming and building gaming computers, I have collected 15 working gaming computers in my life.I will be glad to exchange experience and communicate.

author: fourtytwo42
author_rank: Super Contributor
timestamp: December 10, 2020, 11:05:26 am
content: Welcome I hope you both enjoy your stay