hybridfree/eevblog-posts huggingface dataset:
Magnetic sensitive electronic components - Page 1
Forum section: electronics / beginners

author: RyanT
author_rank: Contributor
timestamp: April 02, 2018, 12:53:19 am
content: Is there a reasonably comprehensive list somewhere of which electronic components I need to keep away from magnets?The only things I've ever seen affected by magnets are magnetic storage media (obviously...), CRTs, and some mechanical or electromagnetic things like some clock movements, speaker coils, reed switches, etc. However, at least these days, I'm more worried about solid state electronic components.In a practical sense, I'm talking about relatively weak magnetic fields, such as that produced by a small (~ 10mm x 5mm) neodymium cylinder magnet at a distance of a couple of cm or more.I'm curious about two related failure modes, actually:Malfunctions in operating circuits, andPermanent damage to (disconnected) componentsHappy Easter.

author: helius
author_rank: Super Contributor
timestamp: April 02, 2018, 12:57:21 am
content: Only MEMS devices like compasses, accelerometers, gyroscopes, DLP imagers, pressure sensors, etc. I guess these aren't totally "solid state" like you asked.Hall devices are solid state and will be affected by magnetic fields, obviously. They should not have permanent damage.

author: retrolefty
author_rank: Super Contributor
timestamp: April 02, 2018, 02:20:22 am
content: The main component I've seen effected by magnetic effects are other transformers in close proximity causing unwanted coupling/interference. Is was an issue in tube based audio preamp/amps and some RF circuits. Normal recommendation was to mount transformers 90 degrees field direction.
Magneto powered moped and oscilloscope - Page 1
Forum section: electronics / beginners

author: billbyrd1945
author_rank: Regular Contributor
timestamp: May 31, 2023, 08:17:20 pm
content: I have a modern digital oscilloscope that I bought in hopes of learning how to use. I never got around to that, so speak to me as a third-grade child. I would like to know if I can do some experiments using the scope and my 1957, single-cylinder, 2-stroke mopedwithoutblowing my scope. Any suggestions would be appreciated. The magneto has 3 coils (ignition, headlight, tailight).

author: Manul
author_rank: Super Contributor
timestamp: May 31, 2023, 08:48:11 pm
content: Not gonna lie, a view of a modern scope hooked to a retro bike would make my eyebrows rise. Not in a bad way, of course.I don't know much about old bikes and what kind of voltages are involved. Can't tell if it is safe to directly probe stuff. My gut is saying that it's not. But I can suggest one guaranteed safe way of having some fun. You can short the probe by hooking ground clip to the tip making a small loop. If you put this loop near components of a running engine, you should be able to see ignition and maybe other interesting signals / noise. You can also wind a small coil if you need more sensitivity. Or buy a specialized "H-Probe". Such magnetic probes are very useful and allow to observe signals in non-contact way.

author: billbyrd1945
author_rank: Regular Contributor
timestamp: May 31, 2023, 08:50:03 pm
content: That sounds interesting. I'll do it.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: May 31, 2023, 08:50:20 pm
content: Google for : automotive high-voltage ignition probeThe probe should keep transients and ESD away from the scope - In theory

author: billbyrd1945
author_rank: Regular Contributor
timestamp: May 31, 2023, 08:52:44 pm
content: That looks interesting too. I'm assuming it steps everything down?

author: G-son
author_rank: Regular Contributor
timestamp: June 03, 2023, 10:41:31 am
content: How high voltage can the scope handle on the inputs? Often is written next to them.

author: billbyrd1945
author_rank: Regular Contributor
timestamp: June 03, 2023, 02:00:54 pm
content: I'll see if I can find out.
Magnetometer urgent help needed! - Page 1
Forum section: electronics / beginners

author: magictouch2020
author_rank: Newbie
timestamp: November 18, 2020, 12:51:33 pm
content: Hello,First off, I have to say I am relatively new to magnetometers.I have been working in a project for the detection of magnets (they can be different sizes) in a three dimensional space around the sensor.The magnets and sensor positions are not strictly defined and they can be in any orientation in space. I am now using the LIS3MDL board to try and accomplish this.I am able to use SensorLab library with MotionCal to obtain relatively good values for calibration.I then use the calibrated magnetometer output values to calculate the magnitude of the magnetic field.By continuously reading the sensor, I check for the increase or decrease in the magnitude value which occur when a magnet approaches from any direction.The problem I have is that over time the sensor will experience drift in the measurements.This will cause the magnitude value, which before was relatively stable, to change a lot as I rotate the sensor.Is there any way to solve this?I have by now done some research and have not reached any answer.Any tips or knowledge would be appreciated.Thank you in advance for any help, really!

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: November 18, 2020, 09:53:49 pm
content: What you're describing isnormal Hall effect sensor behaviour. Plus, in your application, the magnets' fields will merge in complex ways, depending not just on the magnets' positions in space but also on their orientations.Are you sure there isn't a better way to solve this problem? Computer vision, time of flight, retractable tethers ...
Magnets and PCB's - Page 1
Forum section: electronics / beginners

author: jram112
author_rank: Contributor
timestamp: July 31, 2013, 12:21:08 am
content: This may be a dumb question, but ... if you don't know... ask.General question: Can magnets and pcb's populated with IC's co-mingle?Specific Setup: I want to attach a pair of magnets to my 2inx2in pcb and possibly to my battery connection to the pcb (think Apple's Magsafe). My pcb will be on the back of live rodents, and it can be difficult to exchange the battery or pcb. Thus, I want my pcb to just "snap" on and off. I've tried velcro, but haven't been very successful at a good solution. The magnetic field would only fluctuate during removal of the pcb or battery connector.

author: ddavidebor
author_rank: Super Contributor
timestamp: July 31, 2013, 12:43:15 am
content: Cooooool!

author: c4757p
author_rank: Super Contributor
timestamp: July 31, 2013, 01:04:02 am
content: Quote from: jram112 on July 31, 2013, 12:21:08 amYes. A very nearby magnet can apply a small bias to some types of inductors, but still not a big deal unless you stick the magnet right on top.....live rodents?

author: jram112
author_rank: Contributor
timestamp: July 31, 2013, 01:26:10 am
content: Yes. It's a biomedical application.My biggest concern is damaging my expensive IC's. The manufacturer didn't see any problem with the magnets, but I wanted to get other opinions.

author: Psi
author_rank: Super Contributor
timestamp: July 31, 2013, 01:32:56 am
content: Quote from: jram112 on July 31, 2013, 01:26:10 amBiggest concern should be not hurting the rodents.

author: HardBoot
author_rank: Regular Contributor
timestamp: July 31, 2013, 02:59:36 am
content: I'm pretty sure only the act of moving the magnet could be a problem.

author: peter.mitchell
author_rank: Super Contributor
timestamp: July 31, 2013, 03:18:15 am
content: magnets would have very little effect on most things other than inductors/transformers, depending on what components are being used in proximity, it would have little to no effect.

author: ignator
author_rank: Regular Contributor
timestamp: July 31, 2013, 04:33:09 am
content: I don't think the hall effect voltage generated will cause any issues. I can only speak from experience vibrating avionics. The equipment is mounted in front of an electro magnet (vibration equipment are huge speakers), and in 25 years of testing I never saw any upset caused by this field. The CRT on the test station became unreadable, and it was 2 meters away from the vibration coil. I did see an attitude system get upset, but it was using low level piezo crystals to sense the earths gravity. And the effect was a slow over when the electro magnet was turned on. The latest equipment had 7447 processors and ASICs with 1.2volt cores.And in your case, there will only be an external field as you indicate when you switch battery packs.
Magnify viewfinder for using as screen - Page 1
Forum section: electronics / beginners

author: hap2001
author_rank: Regular Contributor
timestamp: September 01, 2023, 03:18:06 pm
content: Hi.I want to find a way to optically magnify EVFs, so I can use them as screens.Upon searching, there are tons of lens that do the opposite - convert screens to EVFs, which is useless to me.Any ideas?Thanks.

author: BeBuLamar
author_rank: Super Contributor
timestamp: September 01, 2023, 04:31:06 pm
content: All EVF's already have the optical magnifier (the eye piece).

author: switchabl
author_rank: Frequent Contributor
timestamp: September 01, 2023, 09:36:55 pm
content: This is likely impractical. You could, of course, use a lens to project the EVF image onto a screen. But, as a result of the magnification, it would be too dim to be useful in most environments (and EVFs aren't usually very bright to start with).You could conceivably build a very large (=very expensive) eye-piece with a high magnification that can be used at a distance. But unlike a screen it would have a very narrow viewing angle.This trade-off is fundamental (energy conservation). There is no way to have magnification and preserve both brightness and viewing angle with a passive optical system.
Magnometer mems sensor - Page 1
Forum section: electronics / beginners

author: blewisjr
author_rank: Frequent Contributor
timestamp: May 16, 2014, 02:50:41 pm
content: I was starting to look into the mems a bit on my discovery board recently. The one mems is a 3 axis accel and a 3d mag sensor. Looking into the mag sensor I noticed it has 3 registers one for each axis. I would assume by what I read in the datasheet is that each register holds a calculated measurement.Now if I was to read the measurement from each axis and add them together would I get a approximate magnetic field reading similar to what a hall effect device would do?The idea is to be able to identify electromagnetic fluctuations in a particular area due to say close proximity to transformers etc...This is more of a experiment for learning arm programming and is a great example of i2c use due to the mems being a slave. This would be a great simple practical example.Are my thoughts correct or off base

author: electr_peter
author_rank: Unknown
timestamp: May 16, 2014, 08:19:52 pm
content: Well, you could use mems magnetometer as a hall effect sensor in theory. In order to do that, you should:make program to read magnetometer registers for 3 axiscalibrate the magnetomer axis (you have to do this, there may be massive offsets). There are great tutorials on the web on calibration, especially from MEMS manufacturerscalculate SQRT[ mag_x^2 + mag_y^2 +mag_z^2 ] and use some threshold in SW to emulate hall effectHowever, in practice you can run into difficulties with SW side, magnetometer mounting, saturation issue and bandwidth problems (see datasheet for magnetometer BW, IIRC BW for magnetometers is pretty low).It sounds like fun project, I encourage you to try.

author: blewisjr
author_rank: Frequent Contributor
timestamp: May 16, 2014, 08:53:55 pm
content: Mounting is taken care of as it is on a discovery board. The max BW I believe if I read correctly is 400kHZ. I figured in theory it should work but what the hell might as well try it out.
Main post always last. - Page 1
Forum section: electronics / beginners

author: electrolux
author_rank: Regular Contributor
timestamp: May 04, 2014, 03:10:04 pm
content: Always when I view a thread on the forum the mainpost is always on th last page which is very annoying. It wasn't like that before what shall I do?

author: Simon
author_rank: Unknown
timestamp: May 04, 2014, 03:15:13 pm
content: you need to look at your display settings, I think you can set them up so that most recent appears first (reverse order) but it's not the default as it makes no sense for most people

author: electrolux
author_rank: Regular Contributor
timestamp: May 04, 2014, 03:22:47 pm
content: Quote from: Simon on May 04, 2014, 03:15:13 pmThanks it works, I just knew you would reply
Main transformer sudden death forensic, looking for cause. - Page 1
Forum section: electronics / beginners

author: anotherlin
author_rank: Frequent Contributor
timestamp: August 05, 2012, 05:31:45 pm
content: Hi everyone,I just have busted main transformer :https://www.eevblog.com/forum/product-reviews-photos-and-discussion/hameg-hm8130-function-generator-teardown-and-repair/I just unsoldered today and double checked it.It has two primary wirings for 110v (parallel them) and 220v (put them in series). One primary has 43ohms and the other one 10kOhm, this one is broken. If plugged, the main fuse keeps blowing.The secondaries seems to have "normal readings" of a few ohms.Hopefully, Hameg stocks the spare, so I can replace it.Yet, I'd like to find out what caused it to break. So as not to buy a new transformer and break it to.I was basically using the generator and it just shuts down (fuse blown), some sort of sudden death.There is a line filter before the transformer, I've checked it, it seems ok.All secondaries are connected to the usual rectifier and filter caps. They seem ok too.Then they all go to voltage regulators, standard 7805, 7815, 7915, and L200.I'm a little bit puzzled as the 78xx series are supposed to have current limiting. So even in case of a short on the main board, the transformer should be protected.Any idea ?Best regards,

author: SeanB
author_rank: Super Contributor
timestamp: August 05, 2012, 05:42:13 pm
content: Shorted diodes, shorted capacitors ( including the ones across the diodes) or open diodes can all either cause the transformer to be overloaded or to have a DC current flow through it ( causes overheating as the core material saturates) and eventually it is hot enough that the varnish breaks down and then crisp time. Could also be a faulty unit that had a shorted turn somewhere that took a few years to break down and become a problem.If you are up to it RS probably still has a DIY transformer kit. You get the core with a prewound and tested primary, and you buy the required wire and wind the secondaries you need, then assemble the core and bolt it up and use it.

author: ciccio
author_rank: Frequent Contributor
timestamp: August 06, 2012, 03:29:51 pm
content: Is the transformer used at 230 V?If so, the measured resistance values are obviously indicating one (or both) faulty primary, but are not directly leading to a blown fuse. In fact, one open primary winding will be in series with the other, resulting in non current drawn.Did you check if there is some form of continuity between primary windings?Regards
Mains Decoupling Capacitor  - Page 1
Forum section: electronics / beginners

author: jonwilhelmjr
author_rank: Regular Contributor
timestamp: March 29, 2024, 02:01:24 pm
content: I have an image of a mains plugging into a piece of equipment. The schematic shows decoupling caps to ground. First question, are these for ESD. Second how are they selected, what calculations should I accommodate to select the correct value. At the very least please provide a circuit description for me to research.

author: Andy Chee
author_rank: Super Contributor
timestamp: March 29, 2024, 02:47:50 pm
content: Not ESD.More likely rudimentary EMI/RFI suppression.https://recom-power.com/en/rec-n-class-x-and-class-y-safety-capacitors-142.html?0

author: selcuk
author_rank: Frequent Contributor
timestamp: March 29, 2024, 03:03:18 pm
content: You may read 15.7 and 15.8 from this book:https://link.springer.com/chapter/10.1007/978-3-031-14186-7_15A short summary about that type of components:https://www.we-online.com/components/media/o156212v446%20Catalogue_EMC%20Filters%20(rev1).pdf

author: madires
author_rank: Super Contributor
timestamp: March 29, 2024, 03:03:43 pm
content: The two caps are for EMI/RFI suppression (low-pass filters shunting high frequencies to PE). Since they are also safety-critical (a shorted cap could be deadly) they have to be class Y safety caps. Theoretically you would choose the capacitance value based on the desired cutoff frequency of the filter. However, there are some important points to consider. The caps will pass a small AC current (50/60Hz mains). This increases the power draw and could also become a problem when the device loses its connection to PE (electric shock hazard). So the current needs to limited to a safe value (not to harm anyone touching a metal part of the device). Another point to consider is the trigger current of RCDs. If you have multiple devices with a high leakage current (via the class Y caps) they could trigger the RCD. And there could be also country specific regulations to limit that leakage current. Therefore the class Y filter caps have usually only a few nF.

author: Vovk_Z
author_rank: Super Contributor
timestamp: March 29, 2024, 03:06:31 pm
content: Quote from: jonwilhelmjr on March 29, 2024, 02:01:24 pmThat's Y-class capacitors (for EMI/RFI suppression). Must be either Y1 or Y2 type. The calculation is quite easy (when simplified). Less then 1000 pF (1 nF) is too low and wan't help much. More then 4700 pF (4.7 nF) can give too much current through them and possibly can hurt people (if not grounded). So, if your device is not very noisy you chose 1.0-2.2 nF Y1/Y2. If your device is powerful and noisy then your choice is 3.3-4.7 nF Y1/Y2.
Mains Earth Ground Stack - Page 1
Forum section: electronics / beginners

author: metrologist
author_rank: Super Contributor
timestamp: November 07, 2019, 07:49:11 pm
content: Are we all aware that the earthing ground wire should be attached directly to the chassis first, and any additional internal ground wires must then be fastened with a separate fastener? For example, a single screw/stud and a single nut should not be used to attach both mains ground and another ground wire that may run to other assemblies, such as PCB or front panel? Should this be common engineering knowledge?

author: james_s
author_rank: Super Contributor
timestamp: November 07, 2019, 08:31:37 pm
content: What's wrong with using a single screw star ground arrangement? I certainly see it done that way in a lot of gear.

author: metrologist
author_rank: Super Contributor
timestamp: November 08, 2019, 01:42:00 am
content: There is an IEC standard, but there seems to be a qualified risk of that one point coming loose and undoing the main earth ground, when other connectors are involved.Another question, also defined is lack of mains supply gap from other circuits. Is there an insulative card that can be inserted between a supply PCB and chassis or other PCB? The "sandwich" will not pass. We need about 0.5mm more gap and there is no room without significant impact.

author: ciccio
author_rank: Frequent Contributor
timestamp: November 08, 2019, 03:55:48 pm
content: In a project that required CE compliance testing and approval from a certified lab, I needed to use the same screw (actually a threaded insert) for both the PE connection and another ground wire.It was acceped but with the following mandatory requirements:The PE wire's ground lug must be the first, with a serrated washer under it (against the case's metal, to guarantee contact even if the case is oxidized), an elastic washer over it (to maintain contact pressure and avoid loosening due to vibration), than a nut that must be serrated with a specified torque.The other wire's lug can sit the top of this nut, and can be locked with another elastic washer and a second nut.And do not forget thar the PE connection must be labeled with the relevant Earth symbol, so any service technician will know that this connection must not be tampered with

author: ciccio
author_rank: Frequent Contributor
timestamp: November 08, 2019, 04:08:02 pm
content: Quote from: metrologist on November 08, 2019, 01:42:00 amI use DuPont's NOMEX paper. There are different suppliers. Even RS has it.Best regards

author: metrologist
author_rank: Super Contributor
timestamp: November 08, 2019, 05:40:54 pm
content: Thanks. This is to comply with IEC 61010-1. We'll ask the test house about the nomex paper for our application.
Need help for mains failure detector - Page 1
Forum section: electronics / beginners

author: Raj
author_rank: Frequent Contributor
timestamp: January 27, 2021, 09:49:02 am
content: So I was making a optocoupler based mains failure detector, (not zero crossing, so I can use capacitor dropper)This is what I came up with. The input voltage is supposed to be 240v at 60hzQuoteSo I need to knowis good enough for 24x7 operation?Should I use NCP785A or LR645N5 instead?Do I have any error in my calculations?

author: Terry Bites
author_rank: Super Contributor
timestamp: January 28, 2021, 03:40:24 pm
content: seeQuote from: Terry Bites on January 08, 2021, 05:48:17 pm

author: Raj
author_rank: Frequent Contributor
timestamp: January 28, 2021, 04:20:40 pm
content: I guess, I'll have to buy some more stuff to make what you have...But I will add a MOV and fuse to my design

author: Raj
author_rank: Frequent Contributor
timestamp: January 29, 2021, 04:04:39 am
content: But Clive just happened to make a video on the same.But the one he has, looks inefficient and too small to meBut 150kShould I not put one of the capacitors in my design?
Mains Input Filter - Page 1
Forum section: electronics / beginners

author: Ranger14
author_rank: Regular Contributor
timestamp: March 04, 2018, 11:59:10 pm
content: I am repairing a Tek 2215 Non A and one of the upgrade was to get rid of the noisy transformer.. Well I can't get the parts for the upgrade and saw in the post they installed a mains input filter.. Right now it has the standard computer style plug and manage to find a common mode mains input filter.. Would it make any difference to install the common mode mains input filter vs a standard plug to pcbThanks

author: Jwillis
author_rank: Super Contributor
timestamp: March 05, 2018, 05:02:25 am
content: A mains line filter keeps power spike and line transient noise from entering your circuit .In your case a oscilloscope.A good one will have surge suppression as well.So for an instrument like your oscilloscope I would put one in.It's a little extra peace of mind.

author: FrankE
author_rank: Regular Contributor
timestamp: March 05, 2018, 06:14:02 am
content: Go for it. They're a few bucks and you should be able to find one of a suitable form factor to easily retrofit into place.I 'm not familiar with the model but as you stated 'old' it'll no doubt be pre EN 55011 CISPR 11 era whatever the US eqIf you have equipment with switched mode power supplies they can put guff on the mains. Input filters work both ways and attenuate the guff and transients going onto the line.Perhaps worth fitting appropriate line filters on other older electrical appliances,
Mains input protection: MOVs, Caps and Chokes, Oh my?! - Page 1
Forum section: electronics / beginners

author: Jebnor
author_rank: Regular Contributor
timestamp: June 15, 2013, 04:43:06 am
content: I'm wondering about mains input protection.In EEVblog #268 at about 5m30shttp://youtu.be/27c4RTntAPw?t=5m30sthere is a great view of all the mains input components. I understand that the Vantrex unit is a high end unit with tight margins and is overkill for any little projects I may have, but could someone explain or provide reference to what the components do and possibly, how to select them?My understanding is this so far:MOVs -- Metal Oxide Varistors: Protect equipment from high voltage short term transients.Capacitors -- I know what they do, in DC mostly. Why do they help on Mains inputs? just Transients again?Chokes -- common mode chokes on Mains input. This one I don't understand at all really. Common mode means they are on the same core right? Does that help with phase alignment of the Mains current or something?References to Lectures, PDF, white papers, application notes and other sources where people know their stuff are accepted freely.

author: c4757p
author_rank: Super Contributor
timestamp: June 15, 2013, 04:56:48 am
content: Quote from: Jebnor on June 15, 2013, 04:43:06 amThe choke is not protection, it's for filtering. Common mode refers to the same polarity, not the same core (though they are on the same core; a CM choke is just a special transformer) - current flowing in the same direction on both sides, so the return path for the current is elsewhere. RF emissions, mostly. The point of the choke isn't even to protect your circuit from noise on the mains, as many beginners assume, but to protect the mains from noise from your circuit (and avoid turning all the wires in your house into SMPS switching frequency transmitter antennas).
Mains Plug through hobby/project box - Page 1
Forum section: electronics / beginners

author: cybermaus
author_rank: Frequent Contributor
timestamp: October 06, 2022, 02:40:31 pm
content: I am trying to find some inexpensive (ebay, ali) project boxes in the format that plugs into the wall, and you can plug another plug into it.With some space below of above for a small ESP plus relay.Something like this:https://www.eco-logisch.nl/images/CV_pompschakelaar_W.jpgDoes not even need to be with display.But I cannot find any. I probably search using the incorrect terms:"Plug through project box""mains plug project box""schuko project box"Any one know any?

author: themadhippy
author_rank: Super Contributor
timestamp: October 06, 2022, 03:01:51 pm
content: Make your own,project box with a plug,drill a hole and fit a panel mounted socket

author: Benta
author_rank: Super Contributor
timestamp: October 06, 2022, 04:06:25 pm
content: Those kind of timers are often "Special Offers" as day/week timers for 5...10 Euro at Lidl and other discounters. Prolly cheaper than buying an empty case.

author: cybermaus
author_rank: Frequent Contributor
timestamp: October 06, 2022, 04:13:58 pm
content: Yeah, but too many displays and buttons.But indeed, I am thinking ofgetting thisand gutting it.Fairly clean and uniform, and I guess I can use one pushbutton.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 06, 2022, 04:17:49 pm
content: I've seen single mains socket adapter with a simple switch (destined to disconnect an appliance from mains without unplugging it). It is a little smaller in size and rather cheap, not reliable for high power. Maybe reuse those.https://duckduckgo.com/?t=ffab&q=outlet+switch+adapter&iax=images&ia=images

author: Jeroen3
author_rank: Super Contributor
timestamp: October 06, 2022, 04:30:55 pm
content: Stekkerbehuizing.
Mains power measurement for low power devices - Page 1
Forum section: electronics / beginners

author: Swake
author_rank: Frequent Contributor
timestamp: September 20, 2016, 12:42:59 pm
content: I'm looking for a relatively cheap mains power meter with a fine enough resolution to allow for reliable measurements on small devices such as USB chargers or a clock or wifi router and the like stuff consuming little power.They are readily available from many stores with a 2500 W or 3000 W range and cost next to nothing. Unfortunately these are not adequate when measuring only a few Watts as their resolution is way to coarse.Nice to have specs:- Resolution of 0.1 Watt; this is about the equivalent of 0.5mA at 230V).- Precision is not critical, 5% or even 10% is acceptable, as long as there is good repetitive accuracy. The goal is to compare for 'home' use not to write a scientific essay.- 20 Watt range is enough.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 20, 2016, 01:40:57 pm
content: About the cheapest thing I could think of is to get a killawatt meter and swap the shunt. I have not tried this but seems doable. I bet someone out there has tried it.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 20, 2016, 01:44:42 pm
content: 2 minutes with Google.http://ecorenovator.org/forum/appliances-gadgets/3597-hacking-kill-watt-very-low-power-measurements.html

author: spronkey
author_rank: Newbie
timestamp: September 23, 2016, 08:03:22 am
content: Whereabuots in the world are you?I have an 'Elto' power meter in New Zealand. They have two 'types' (http://www.energymonitor.org.nz/ema1type1-type2-differences) - Type 1 isn't nearly accurate enough, but type 2 could be close - it claims +/- 0.2W accuracy, and has a measurement range of 0.2W to 2760W, displaying a single decimal place on the display.I'm no expert, and certainly not on the safety aspects, but would something like theUni-T UT210Eclamp meter suit? I've been considering one of these myself, but the repeatability may be an issue at really low amperage (although, I guess you could wind the cord around a few times if it would fit?).

author: The Electrician
author_rank: Frequent Contributor
timestamp: September 23, 2016, 09:38:00 am
content: On this forum you can find:https://www.eevblog.com/forum/testgear/yokogawa-cw-10/https://www.eevblog.com/forum/projects/measuring-standby-power/

author: SeanB
author_rank: Super Contributor
timestamp: September 24, 2016, 08:07:28 pm
content: Quote from: joeqsmith on September 20, 2016, 01:40:57 pmi took a regular mechanical kilowatt hour meter and slightly adapted it using a current transformer, so that it went from 60A FS to 6A FS, using a 10:1 current transformer wound on an old toroidal transformer core.Interesting that the current reading is 1112.2 kWh, I did reset the meter movement to zero when I modified the meter, and this is the cumulative power use over a period of around 5 years.
Mains voltage multiplier HV DC supply question - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 29, 2013, 08:57:55 pm
content: How does this work the inductors, (and relay), are a mystery, I know how a normal doubler, or tripler etcetera works but this seems one step beyond:http://www.ur4ll.net/#trans3See item Multiplier X4Thanks.

author: fcb
author_rank: Super Contributor
timestamp: November 29, 2013, 11:03:01 pm
content: If you look at the board, it says +600 and -600.My guess is it is simply two multipliers, one for neg and one for pos.The other stuff is perhaps filtering and a relay to switch on the thing, perhaps with a current limiting w/w resistor.

author: Psi
author_rank: Super Contributor
timestamp: November 29, 2013, 11:49:45 pm
content: Is there supposed to be a circuit for this 4x multipler on that page, i cant see itEdit: hm.. that's odd, it just magically appeared the next time i loaded the page.

author: Chris Wilson
author_rank: Super Contributor
timestamp: November 30, 2013, 12:25:18 am
content: I can't see a circuit. Just a .jpg of the board.... Is it a .pdf or what? Thanks.

author: Psi
author_rank: Super Contributor
timestamp: November 30, 2013, 01:33:09 am
content: It's just a link to a photo of the PCB, I shouldn't have used the word circuit.
Maisheng MS-605D  - Page 1
Forum section: electronics / beginners

author: solderjoint
author_rank: Newbie
timestamp: December 10, 2022, 08:06:29 am
content: HiAllI was hoping the owners of the Maisheng MS-605D Power Supply can help pleaseI read here that people replaced the potentiometers but nkomo posted details of replacements used.Please can someone/ anyone post details of potentiometers including shaft sizeI'd prefer to keep stock potentiometers and not upgrade themThanks allI was reading your post aboutMaisheng MS-605D Power SupplyPlease can you let me know which potentiometers you usedI need to know the specifications and shaft sizeMany thanks
Major score at my local radio shack - clearance sale! - Page 1
Forum section: electronics / beginners

author: nbritton
author_rank: Frequent Contributor
timestamp: September 27, 2015, 11:36:14 pm
content: My local radio shack is having a clearance blowout sale, everything is half off the clearance price for every $20 you spend. I picked up $750 worth of kit for $317!Here is what I got:2x Extech EX210T True RMS + IR temperature Multimeters. $34.25 eachRS 2200172 AC/DC Digital Clamp On Multimeter. $13.46Make Ultimate Microcontroller Pack: $49.96Make Component Kit 1: $37.46Make Component Kit 2: $29.96RS 2770136 Basic Component Kit: $22.96Make Soldering Station Starter Kit: $24.962x Parallax BASIC Stamp 2 Experiment Board: $14.96 eachSeeedstudio ARDX Starter kit: $19.96Motor Pack Kit for Arduino: $19.96

author: edy
author_rank: Super Contributor
timestamp: September 28, 2015, 12:43:24 am
content: I am seeing a bunch of RadioShack stuff for cheap (although not cheap enough in my opinion) at the surplus section of "Princess Auto" chain of stores in my area (Canada). They have piles of Arduino shields. But I am waiting until they go lower. Maybe they will be gone by then, but I have no immediate need for them and so it will just end up on my workbench collecting dust until I get around to it.

author: rickselectricalprojects
author_rank: Regular Contributor
timestamp: September 28, 2015, 01:06:46 pm
content: nice

author: MrWizerd
author_rank: Contributor
timestamp: September 29, 2015, 12:35:32 am
content: They are doing half off all of there clearance stuff at my radio shack, if you spend 20 bux. Which is crazy there is a 300 dollar drone you spend 20 bux and get it for half off. There is also some other stuff, but most of there arduino stuff is gone, there are some kits but most of those have stuff I already have a lot of, the case is nice though. It is sad to go in to radio shack and see it devoid of anything useful anymore. Sure there is a cabinet of stuff but its almost always empty of what you need I can't even get heat shrink tubing there anymoreIt really is a crying shame, an institution has all but died.

author: crispy_tofu
author_rank: Super Contributor
timestamp: September 29, 2015, 11:32:00 am
content: WOW great score!Should've bought everything and resold it for a nice profit
Why a free electrons the majority carriers in n-type semiconductors - Page 1
Forum section: electronics / beginners

author: petert
author_rank: Regular Contributor
timestamp: September 19, 2019, 06:27:35 pm
content: Hello,This is more of a physics question, so I am not sure which category fits best.I understand that n-type semiconductors have more free electrons than holes, but I don't get why from the way they are constructed by doping.To explain, let me quote fromhttps://www.halbleiter.org/en/fundamentals/doping/:QuoteSo on one hand the dopants, for example phosphorus, will provide the free electrons. Yet this will also make the dopant/donor positive. How can you have more free electrons than holes (which appear in the dopant)? I don't see how this would not balance out to be of neutral charge overall.

author: rfeecs
author_rank: Frequent Contributor
timestamp: September 19, 2019, 11:25:18 pm
content: Quote from: petert on September 19, 2019, 06:27:35 pmThe phosphorous atoms provide the free electrons. The ionized phosphorous atoms are positively charged, but they are fixed charges.They are not holes.As you say, overall the N-type material is neutral. With each phosphorous atom you add a (mobile) free electron and a (fixed) positive charge.

author: kosine
author_rank: Regular Contributor
timestamp: September 20, 2019, 02:53:11 pm
content: Semiconductors - however doped - are electrically neutral. For every proton, there's an electron. So no net charge. Period. (If there was any residual charge they'd attract each other like magnets, pick up fluff, be used as batteries etc.)What the doping does is create dangling atomic bonds. In pure silicon, each atom forms 4 bonds, but when doped it can't quite do that because some atoms will want to make 3 or 5 bonds instead. When there's an excess of 5-bond atoms it's N type. These dangling electrons are still attracted to their parent atom, but because they're not forming a complete bond with the surrounding silicon (or germanium) they are relatively easy to dislodge. They then become a mobile charge carriers which give rise to a current.Their parent atoms are now positively charged ions and will try to grab a electrons from somewhere nearby. The application of a voltage therefore causes a leap-frog of electrons through the crystal, and that's roughly how it works. Swap the electrons for holes for P type.
Make a dumb fan into a smart one? - Page 1
Forum section: electronics / beginners

author: maybepanic
author_rank: Contributor
timestamp: November 18, 2024, 04:06:12 am
content: Hey,I've got a fan that can be regulated via an analogue potentiometer. It's a simple 0-10k Ohm pot. No pwm or anything like that. I guess it's simply reading the voltage drop across the pot.I'd love to regulate it with a raspberry pi. Is there an easy way to do this without having to mess with the fan's pcb itself?Thanks!

author: brucehoult
author_rank: Super Contributor
timestamp: November 18, 2024, 04:13:22 am
content: How much voltage is across the pot? It's just a simple low power carbon film pot, not a high power wire-wound rheostat or anything?It it's low voltage (and DC) and it's just being a low current voltage divider then yeah no reason you couldn't replace it with an analogue output from a microcontroller/Pi. Probably PWM would be fine too, but a bit of smoothing might be good. Maybe with an op amp or transistor added if it's over 5 V.

author: Ian.M
author_rank: Super Contributor
timestamp: November 18, 2024, 04:39:20 am
content: However if its a mains powered fan, it is quite likely that the control circuit is non-isolated i.e. all the pot connections are a mains live shock hazard. If the original pot has a plastic bushing and shaft, its certain to be non-isolated. Interfacing a Pi safely to a mains live analog control circuit is not so simple . . .Some expensive mains fans intended for home automation have an isolated analog control interface, typically 0-10V with a low current 10V supply in the fan to feed the pot, so can be controlled by a MCU without safety risks.Telling the difference may not be easy, so if you have a link to the fan manual or installation guide post it for us to check.

author: techninja80
author_rank: Regular Contributor
timestamp: November 21, 2024, 05:39:24 pm
content: Use a transistor like a MOSFET, and turn it on and off with the PI, or even regulate the speed with it too.
Make a LCD  - Page 1
Forum section: electronics / beginners

author: huu_tri0101
author_rank: Contributor
timestamp: February 13, 2013, 11:41:16 pm
content: On any DMM has a LCD. Can I make this LCD by myself with my icon on it ?

author: FenderBender
author_rank: Super Contributor
timestamp: February 13, 2013, 11:58:35 pm
content: Do you mean getting a custom LCD made to have certain characters on it. Surely you can. However, you will need to order in a pretty large quantity and it may be somewhat expensive.

author: mariush
author_rank: Super Contributor
timestamp: February 14, 2013, 12:17:23 am
content: As above, you can talk to a lcd manufacturer to make you an lcd screen with all the icons and segments for digits where you want them. But you'd probably need to order 1000 or so for them to have a profit or be interested to do it.Or, if you don't need to have those high contrast icons with nice shapes, you can get lcd screens that are dot matrix, meaning you can turn individual pixels on and off, something like this for example:http://www.digikey.com/product-detail/en/NHD-C12864GG-RN-GBW/NHD-C12864GG-RN-GBW-ND/1701323You can see the individual pixels and how big they are. Also, there's loads of similar lcds that also have easier to use connectors, just check the link above and the category the lcd is in.

author: huu_tri0101
author_rank: Contributor
timestamp: February 14, 2013, 01:28:30 am
content: thank you all guys.
Make a PMOS open drain circuit in LTSpice - Page 1
Forum section: electronics / beginners

author: Saimoun
author_rank: Frequent Contributor
timestamp: July 23, 2021, 01:57:07 pm
content: HiJust a quick question: I know more or less how an open drain works - pullup resistor, and then a NMOS with it's source connected to ground.I am trying to do the same with a P-MOS, basically a pulldown resistor and a PMOS connected to +5V. Kind of the upper part of an MCU push-pull output.I tried in LTSpice and I cannot seem to get it to work? It seems changing the type of PMOS makes a difference but the output never goes to 0V or even near that.See the attached schema.Thank you

author: fourtytwo42
author_rank: Super Contributor
timestamp: July 23, 2021, 02:01:48 pm
content: I am sure there was a similar question on here recently,However, check your polarities, they are wrong ANDYou say you want open drain but it is your source that is the output in that circuit

author: Saimoun
author_rank: Frequent Contributor
timestamp: July 23, 2021, 02:06:49 pm
content: Ahhh ok that was dumbYes it works better the right way
Make a simple soft-shutdown circuit - Page 1
Forum section: electronics / beginners

author: ratatax
author_rank: Regular Contributor
timestamp: August 10, 2020, 08:56:33 am
content: Hi,I have a polarity protection circuit using a P channel mosfet that is working (Q1, R9, D28). R9 was initially connected to ground.I'd like to add a switch to:- Power on the circuit when it's pressed (no need for latching circuit, the switch keeps its position)- When the switch is turned OFF, the MCU keeps the circuit active until it decides to shut it down by itself.Since the switch I use is DPST, I guess one contact can be used to tell the MCU when the user wants to power down the circuit, then with the additional MOSFET force Q1 to switch off by setting MCU_POWEROFF_CONTROL to input (high impedance). I'd like to use a p-ch mosfet too for BOM simplicity.I'm a beginner, would that work ?

author: Ian.M
author_rank: Super Contributor
timestamp: August 10, 2020, 10:08:02 am
content: That wont work. The body diode of the reverse polarity protection MOSFET will conduct so all the power on/off circuit will do is lower the power rail by the body diode Vf drop when off.To make it work, you need a separate P-MOSFET for power control, with its source fed by your reverse polarity protection MOSFET.

author: ledtester
author_rank: Super Contributor
timestamp: August 12, 2020, 03:50:37 am
content: I would look at Dave's video on a soft latching power switch for ideas:https://youtu.be/Foc9R0dC2iIHis goal is to have a momentary switch both turn power on and off, but there's enough details of how the circuit works to see how to shut the power off via a digital signal.

author: Peabody
author_rank: Super Contributor
timestamp: August 12, 2020, 04:11:24 am
content: Here's a circuit that uses a push button to power everything up, and it's an input to the processor as well. Then the processor maintains the power and turns it off when ready. But the polarity protection would need to be added ahead of all this. The orientation of the protection mosfet is opposite that of the switch mosfet.Also, you might try to find a mosfet that will handle a GS differential of something like 20V so you wouldn't need to use zeners.
Make a USB charge point from DC input - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 16, 2017, 04:42:10 pm
content: I have to make dc charge input from two options below, so that any mobile or related device can be charged:1. Input: 17.5V-29.4VdcOutput : 5V/1A for USB chargingLed: Led indication when mobile is plugged in i.e charging occurringLed off when charging completes or nothing is plugged in2. Input: 7.5V-12.6VdcOutput : 5V/500mA for USB chargingLed: Led indication when mobile is plugged in i.e charging occurringLed off when charging completes or nothing is plugged inSince I need low cost option, so I am planning to use LM2576 option for both of them.Lowest I think would be LM7805, but it gets heated up evn in case of 12.6V & 500mA option also. Since it produces wattage of around :(12.6V-5V)*0.5 = 2.55WSo I am not using this.1. Is there any other low cost solution which can be used, in which inductor is not be used externally. Dont want to use it since not availble in low cost option in local market.2. I also want to limit the current to 500mA & 1A so that any device should not be able to draw more current. What should I do in this case? What is recommended use for this. Or let the load draw more current in case of error/overload, LM2576 will thermal shutdown in case of over-temperature.3. Led indication when charging happens i.e when current is flowing. Should I place a current sense & place a op-amp across it & make a led glow or any other option also available?
Make arduino enter Void loop() only after a button is pressed, possible? - Page 1
Forum section: electronics / beginners

author: MrOmnos
author_rank: Frequent Contributor
timestamp: December 17, 2015, 05:52:04 pm
content: I want my arduino to go into void loop only after a button is pressed. Like a start button. How do I do that?

author: Ian.M
author_rank: Super Contributor
timestamp: December 17, 2015, 06:03:38 pm
content: The Arduino IDE automatically adds a main() function that closely resembles:Code:int main(void){init();setup();for (;;) {loop();}return 0;}So, simply wait for the button at the end of void setup().
How can I Make a  DPDT switch with timer using electronics   - Page 1
Forum section: electronics / beginners

author: Mikek400
author_rank: Regular Contributor
timestamp: March 02, 2015, 11:26:18 pm
content: Sorry, this is a very beginner question.I would like to make something equivilant to a DPDT switch that automatically switches. For example, plug a usb connector and it waits 3 seconds and flips the DPDT switch. We can detect the USB plug in by using the Shield and the GND wire. When plugged they are connected.I was thinking a 555 and some transistors might be able to do this, but I am just getting into electronics and don't really know where to start.I have a tablet that has a single micro usb port for charging and for usb data connections (USB OTG Host). Unfortunately this tablet doesn't follow the USB OTG standards. If it did a resistor between pin 4 and 5 would solve my problem.I have figured out how to get it to charge and accept data connections at the same time. I connected the data lines to a DPDT switch. One side of the switch shorts the data lines together, therefore putting the device into charge mode. The other side of the switch has the data lines of a USB hub connected to it.Please see attached JPGSo plug it in flip the switch and its charging and working in USB host mode. It only needs to short the data lines when first plugged in, maybe 3-5 seconds and then switch over to usb hub data lines.I want to make a small circuit to get rid of this switch and make it automatic but I'm not sure where to start. Any advice?Thanks in advanceMike

author: eejake52
author_rank: Contributor
timestamp: March 03, 2015, 05:12:52 pm
content: You could use a 555 and a small relay (e.g.http://www.kemet.com/Lists/ProductCatalog/Attachments/527/KEM_R7002_EC2_EE2.pdf)If the data lines just need to be shorted to ground (as opposed to each other), then you could use 2 NPN transistors instead of a DPDT relay.

author: Mikek400
author_rank: Regular Contributor
timestamp: March 04, 2015, 12:11:08 am
content: Would it be possible to use FET and a JFET with a cap in circuit to do this?Cap charging up and turns off JFET while turning on the FET.

author: N2IXK
author_rank: Frequent Contributor
timestamp: March 04, 2015, 12:26:26 am
content: 555 driving an AD7512 or similar?

author: Mikek400
author_rank: Regular Contributor
timestamp: March 04, 2015, 02:28:52 am
content: That looks promising. Thanks!