hybridfree/eevblog-posts huggingface dataset:
LCR Meters - Page 1
Forum section: electronics / beginners

author: Legion
author_rank: Frequent Contributor
timestamp: March 14, 2014, 05:23:56 am
content: As someone new to electronics I've only recently become aware of LCR meters. Couple questions.1. DMMs, scopes, FGs and DC power supplies are featured prominently in most introductory electronics courses and books, but not LCR meters. Why? Are they only used for very special circumstances? Books like "Practical Electronics for Inventors" state "The three cornerstones of electronics are resistance, capacitance and inductance." Based on that statement, the name "LCR meter" alone would make me think it's one of the most important pieces of test equipment for general electronics. Clearly though, that's not the case.2. Why not just roll all of that functionality into a DMM? Why a separate device? Is it a technical problem or a business one?

author: BravoV
author_rank: Super Contributor
timestamp: March 14, 2014, 05:31:32 am
content: Quote from: Legion on March 14, 2014, 05:23:56 amBusiness, not every one needs LCR functionality into a DMM which mainly only for volt, resistance and current measurements.

author: Shock
author_rank: Super Contributor
timestamp: March 14, 2014, 09:45:04 am
content: They have been around ages as expensive bench meters, mine is about 25 years old.Before that since the "dawn of time" as separate instruments.Over the years technology has become better, smaller and more affordable to the point where buying a handheld LCR meter isn't a big deal as it once was.Like everything though, unless your using it - pointless getting it.
Lcr-t4 nightmare  - Page 1
Forum section: electronics / beginners

author: Omarsamso
author_rank: Newbie
timestamp: May 21, 2020, 12:19:47 am
content: Hi guys. I need help urgently, I've tried many times and given up.I have an lcr-t4 tester which the display has been destroyed, I'm trying to hook it up with a display of a mixer.Please help configure.

author: tooki
author_rank: Super Contributor
timestamp: May 22, 2020, 08:11:01 pm
content: Ummm, just search eBay and AliExpress for the correct kind of LCD. The picture you show looks like it’s a character LCD, which isn’t a drop-in replacement.

author: madires
author_rank: Super Contributor
timestamp: May 22, 2020, 08:23:35 pm
content: The T4 has a ST7565 compatible display.
LCR-T7 Tester 3 pin short Self test and Calibration not working anymore - Page 1
Forum section: electronics / beginners

author: AmigaWolf
author_rank: Newbie
timestamp: April 07, 2019, 06:12:26 am
content: For some strange reason, the LCR-T7 Tester 3 pin short Self test and Calibration is not working anymore.And the battery does not want to charge, everything else is working, but he gives me the wrong values, because i cannot do the Self test and Calibration anymore.What must i do now?
LCSC driving me mad looking for momentary switches - Page 1
Forum section: electronics / beginners

author: owl_uk
author_rank: Contributor
timestamp: September 22, 2025, 03:48:10 pm
content: So this could be an issue with me being stupid but I'm looking for momentary switches for my project on LCSC. I want a 3 position momentary toggle switch, so I can push it up or down and it springs back to the middle. I can see some parts which clearly state they are mom-off-mom in their data sheets but none of them are in stock, e.g. C&K ET05 series. But I can also see a lot of parts, eg MT-0-103-L001-D000-RS where the data sheet shows the pin connections in each position, but doesn't explicitly say whether it is momentary or latching. Has anyone else had this problem?

author: Nominal Animal
author_rank: Super Contributor
timestamp: September 22, 2025, 08:38:07 pm
content: C&K 7000 serieshas7105: Single pole Mom-Off-Mom, for example C26896247205: Dual pole Mom-Off-Mom7305: Triple pole Mom-Off-Mom7405: Quad pole Mom-Off-Mom7215: Dual pole Mom-On-Mom, for example C28955837415: Quad pole Mom-On-Mombut yeah, the LCSC parts search isn't very good. I often use Digikey and Mouser to find parts and series, then look at where LCSC has categorized it.

author: thm_w
author_rank: Super Contributor
timestamp: September 22, 2025, 09:21:16 pm
content: Datasheet:https://www.lcsc.com/datasheet/C22448937.pdfIf it says ON OFF ON then its not momentary, normal terminology.You want MOM OFF MOM or (ON) OFF (ON) which is the 123 series. I'm sure there is a part number guide somewhere out there.https://www.lcsc.com/search?q=MT-0-123&s_z=n_MT-0-123
LD1117S50TR thermal pad - Page 1
Forum section: electronics / beginners

author: hosko
author_rank: Newbie
timestamp: January 09, 2018, 06:16:31 am
content: Just a quick question is the thermal pad meant to be to ground? If not where does it go, sorry I haven't really used smd components very often. I'm more use to the through variety.On a design a have tied it to ground, I am not getting any voltage on the Vout and the chip is getting very hot. I think I have answered my own question, just wanting to double check before I remove some copper with a strip board drill.Thanks

author: marshallh
author_rank: Unknown
timestamp: January 09, 2018, 06:39:18 am
content: No, the tab is connected to the middle pin.Check datasheet. Pinout is GND, Vout, Vin, so tab is Vout.

author: hosko
author_rank: Newbie
timestamp: January 09, 2018, 06:43:32 am
content: Ahhhhhhhhhh so I have shorted it, hopefully I didn't damage the Voltage Reg.Thanks

author: phil from seattle
author_rank: Super Contributor
timestamp: January 09, 2018, 09:10:30 pm
content: I suspect it's a goner. This situation is why I always order a few extra.And, I hate VRegs that don't have the large tab or slug connected to gnd. I want to use the ground plane on a PCB as a heat sink. I have toasted more than one LM317 by forgetting the tab is Vout.
LDO linear voltage regulator for ESP8266 - Page 1
Forum section: electronics / beginners

author: n0f8r
author_rank: Newbie
timestamp: September 25, 2020, 02:38:57 pm
content: Hi All,I have a board with an ESP8266 module on it - this one:https://www.aliexpress.com/item/32311028307.html?spm=a2g0s.9042311.0.0.27424c4dtzgihN.The board takes 24v and uses a switching regulator to drop that down to 4.5V which is then fed into a 3.3V linear regulator - this one:https://www.mouser.co.uk/ProductDetail/621-AZ1117EH-3.3TRG1?r=621-AZ1117EH-3.3TRG1which then feeds into the ESP module with a pair of 22uF mlcc caps across the LDO regulator output and the power in of the ESP module.My question is on LDO Linear Reg output and whether it's normal to see 3.3v with +- 0.25V variation, ie spikes down to 3V and almost up to 3.6V?I have a high board failure rate - where sometimes the ESPs just seem to go haywire (stop responding, slow to respond, random reboots) something like 10% of them in fact. Initially I thought maybe I'm getting bad quality ESP modules form China - and I'll just have to live with it. I tried de-soldering the ESP modules on a few bad boards and re-soldering fresh ESP modules on, they seemed to work ok for a bit, but then two of them started acting up again.So now I'm wondering if it could be the linear regulator I'm using, or how I'm using it. I'd guess the 22uF power filter caps I'm using are probably too big for purpose, maybe way too big, but that's only a BOM expense issue right - it wouldn't cause voltage spikes? Google tells me 3.6v and higher can kill the ESP8266 - I put one of the re-soldered boards on the scope and I'm seeing 3.3V plus/minus 0.25v on the ground and VCC of the ESP module - to be clear, at 100 micro seconds per division the voltage graph line looks very stable to the human eye, but the scope stats tell me there are peaks over 3.5V and lows almost down to 3.0V. Is that normal to expect coming out of a 3.3v LDO regulator?any tips/pointers/questions appreciated.thanks,Kevin.
LDO Regulator 0..36V 1.1A Parallelable - Page 1
Forum section: electronics / beginners

author: rstofer
author_rank: Super Contributor
timestamp: November 18, 2016, 12:51:16 am
content: It comes up from time to time that somebody wants to build a power supply that can get down to 0V. I don't know why that is a requirement, but it is!So, I was wandering around the Linear Technology site when I ran across a 1.1A LDO regulator that can get down to 0V and go up to +36V. It can also be paralleled to provide more current. Seems like a pretty cool regulator. LT 3080-1 is the device:http://www.linear.com/product/LT3080-1Less than $3 direct from Linear Technology.
LDO with two output pins - do I have to use both? - Page 1
Forum section: electronics / beginners

author: zapta
author_rank: Super Contributor
timestamp: August 13, 2016, 01:19:29 am
content: This SOT-223 LDO has two output pinshttp://www.diodes.com/_files/datasheets/AP2114.pdfIs it OK to use only one of them (e.g. that large tab)?(motivation: tight PCB)

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 13, 2016, 01:38:04 am
content: Hi,It is o.k. to use one of them. The datasheet shows some parts with the extra pin cropped short.Jay_Diddy_B

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 13, 2016, 02:29:19 am
content: not just ok, its common. you can even crop either the sot-223 middle pin or the large tab or solder them vertical.

author: zapta
author_rank: Super Contributor
timestamp: August 13, 2016, 03:10:35 am
content: Thanks, this will save me two big and ugly vias.
LDR to 'stop' a button click? - Page 1
Forum section: electronics / beginners

author: Grytpype
author_rank: Contributor
timestamp: June 10, 2025, 12:26:16 pm
content: Hi all!I'm 'made' a clock that plays an MP3 on the hour. I've got a simple clock that joins two prongs together on the hour to act as the mechanical button push on a cheap device that plays a short file via a small speaker.I've been trying to work out how to stop this playing at night and have been looking for some sort of circuit to prevent this happening if the light levels are below a certain level but have drawn a blank. As you can see from the hi-tech diagram it's a pretty straight-forward set up.Any ideas / pointers very welcome as the mrs will probably kill me if she hears Rik from the Young Ones shout "Hands up who likes me?!" one more time.Ta!

author: MK14
author_rank: Super Contributor
timestamp: June 10, 2025, 01:03:42 pm
content: If the MP3 switch input, is a rather low current affair.You might get away with inserting into the wire pair circuit (in series, i.e. cutting the wire and putting the LDR between the two cuts), an LDR.The LDR in bright daylight should hopefully conduct enough electricity, to allow the virtual push switch (from the hourly clock signal), to still work.But at night, be high enough resistance (hopefully, but not definitely), to get it to shut up!Edit:Failing that (working). You may need to use a transistor, switched by the LDR, to perform the switching.

author: Grytpype
author_rank: Contributor
timestamp: June 10, 2025, 03:17:19 pm
content: Thanks MK14 - will give it a tickle and update.I've seen and made a few beginners LDR with transistor circuits to turn on an LED so will try something along those lines if the latter fails.Ta!

author: Zero999
author_rank: Super Contributor
timestamp: June 10, 2025, 06:04:25 pm
content: How about a comparator circuit? Put a relay or opto-coupler (it might have to be back-to-back MOSFETs, if it's multiplexing) on the output and connect it across the switch contacts.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: June 17, 2025, 12:23:19 pm
content: Quote from: Grytpype on June 10, 2025, 12:26:16 pmYou can use an LDR, a 10kΩ resistor to create a voltage divider with the LDR. For switching, you can use an NPN transistor (like 2N2222 or BC547) or a MOSFET like IRFZ44N.
LDR Transistor Switch Bad Circuit? But why? - Page 1
Forum section: electronics / beginners

author: TinkerFan
author_rank: Regular Contributor
timestamp: February 25, 2016, 09:41:10 pm
content: G'day guys,I just came across this schematic in a physics lesson (we didn't test it) and I was wondering, because the circuit seems to be wrong (or impractical). I built it up with LTSpice and a bit of a playaround with it. The load was not specified (probably a light bulb; LED's seem to be unknown in physics lessons)Original schematic:https://kitronik.co.uk/blog/how-an-ldr-light-dependent-resistor-works/The upper base resistor is a fixed value, while the lower one is the LDR (it was said before, that its value is between 5k to 20M). The load is between collector and supply rail (So a normal collector circuit; transistor as a switch, right?).I then tried to choose the fixed resostor(31k), so that the transistor is just switched off, when the LDR is at its lowest value. But the Emitter resistance is much to low, so that the LDR can have any effect on the bias for the base. And indeed, something is not really working here: The voltage is just above Vbe, so the transistor is turned on and saturated, but it doesen't depend on the value of the LDR. But if the LDR has 5k (its lowest value), the transistor will get into its active region, having the base at 3.6V (what is happening here?).How could one improve this circuit? Put a large resistor at the base?Could someone please explain how this (is ment to) works and how far I am right?I'm sorry, if this is a really stupid question, but I am kinda stuck here and my English could also be better...Thank YouTinkerFanPS: The output at the collector is shown in the attachment (green is at 5k and 1meg is grey)

author: Seekonk
author_rank: Super Contributor
timestamp: February 25, 2016, 10:08:16 pm
content: These overly simplistic circuits seldom work very well. However,if you replace the transistor with a LM431 it would. It has a sharp transition at 2.5V and can easily drive a 50ma load like a small relay or LED. Understand that the saturation voltage will be around 2V.

author: ataradov
author_rank: Super Contributor
timestamp: February 25, 2016, 10:17:30 pm
content: Why is there your profile form in the first picture?

author: TinkerFan
author_rank: Regular Contributor
timestamp: February 25, 2016, 11:23:13 pm
content: Thank you for that info, I didn't check it...So this will never work due to the low impedance od the emitter? The opamp idea is overcoming this problem, right?
Lead - Lag IC detector - Page 1
Forum section: electronics / beginners

author: IvoS
author_rank: Frequent Contributor
timestamp: February 21, 2014, 05:13:54 pm
content: I am about to start designing a simple ultrasonic detector. I will use Rx and Tx piezoelectric transducers. I wonder if there is any IC with 2 inputs lets say that can detect lag and lead rise edges of square wave with minimum parts around, instead of spending too much time trying to figure out a way myself using D or JK flip flops and similar logic ICs. Thanks.

author: granz
author_rank: Regular Contributor
timestamp: February 21, 2014, 07:30:28 pm
content: Sounds like you want a phase detector. Here's one that might work for you from ON Semi:MCH12140http://www.onsemi.com/pub_link/Collateral/MCH12140-D.PDFIt basically implements the logic for you such that you get a pulse-width out of one pin or the other which is proportional to the lead or lag time.Depending on what you are going to use in regards to a microcontroller and how low your ultrasonic frequency is, you could probably also use your Tx oscillator to trigger positive-edge interrupts, and then the Rx side to also trigger positive-edge interrupts. If your microcontroller is running fast enough you could time the difference between the two interrupts. You'd need a much faster uC to get any resolution though.

author: Zero999
author_rank: Super Contributor
timestamp: February 21, 2014, 08:24:34 pm
content: A good IC but perhaps it's a bit overkill?What about a PLL IC such as the CD4046 or ithe improved 74HC4046? It includes an VCO too, which you may be able to use to drive the piezo transmitter.

author: IvoS
author_rank: Frequent Contributor
timestamp: February 21, 2014, 11:21:13 pm
content: Thanks. I will look into those two chips. I already built and tested oscillator made out of 74AC14 that has rising edge 3.5ns driving the transmitter straight from its outputs and it works beautifully. I can get around plus minus 200 - 300 mV sine wave output from the receiver depends on the distance. The working frequency is only 40kHz though. I don't need to and I don't want to use any micro. I just want to be able to adjust sensitivity or phase delay and then send it to simple logic and trip the relay.

author: granz
author_rank: Regular Contributor
timestamp: February 22, 2014, 05:31:17 pm
content: Cool. Sounds like you should go with the generic CD4046-type parts in that case. With that low frequency those parts should be fine. A lot of industrial ultrasound is actually up in the several MHz range, and I believe the CD4046 is only good up to something like 2 MHz. (The 74HC4046 is faster though I believe). I'd be interested to see your design when you have it working
Lead on Lead-Free iron tip - Page 1
Forum section: electronics / beginners

author: warmage
author_rank: Newbie
timestamp: January 30, 2013, 06:25:29 am
content: Helloz,i got a Hakko fx888 with lead-free tip , and i got tips from ebay that are lead-free , can i use lead wire core on themi dont use lead-free at all , and i cant find any Lead tips anywherei use Lead 60/40 and kester 44, 63/37

author: Psi
author_rank: Super Contributor
timestamp: January 30, 2013, 06:29:49 am
content: I'm pretty sure you can use lead-free tips with lead solder without issue.If working with both types you ideally want a separate tip for each, but most people don't bother and just make sure to clean the tip between uses.

author: warmage
author_rank: Newbie
timestamp: January 30, 2013, 06:38:39 am
content: So its safe to use lead on it , as long as i dont mix it with lead-free (which i dont have or plan to use)

author: Psi
author_rank: Super Contributor
timestamp: January 30, 2013, 06:51:53 am
content: I'm not 100% sure, but I've never specifically purchased "lead tips" for lead soldering.And i've never had any issues.In fact, most of the time the tips don't say lead or lead-free at all.I'm sure someone else will know for sure.

author: nanofrog
author_rank: Super Contributor
timestamp: January 30, 2013, 07:22:15 am
content: Yes you can use the lead-free tips for lead alloys.I'd recommend rinsing them with a lead alloy solder first before actually soldering anything first though (keep applying leaded solder for awhile, to "rinse" off the lead-free alloy that it was tinned with during manufacture). The purpose of this, is to keep from getting some unknown alloy with properties that could cause problems on the first joints you make. Doesn't take long, and is easy to do.

author: warmage
author_rank: Newbie
timestamp: January 30, 2013, 07:28:57 am
content: Thanks for the info and help

author: ConKbot
author_rank: Super Contributor
timestamp: January 30, 2013, 05:59:05 pm
content: Quote from: nanofrog on January 30, 2013, 07:22:15 amFrom the nasa hand soldering training Ive attended, "rinsing" 3 times is enough to get the alloy of the tip nice and homogenous with the 63/37 or 60/40 youre using. Just wipe all the solder off the tip you can, add a nice big blob, repeat.It wasnt in the training manual, but the professor seemd old and crusty enough to know his stuff inside and out and backwards.(found a .pdfof the workbook for anyone interested. good technique, not always appliciable for "normal" electronics )
Lead solder - Page 1
Forum section: electronics / beginners

author: GAM3x0V3R
author_rank: Newbie
timestamp: February 27, 2020, 09:18:12 am
content: Hi all im in desperate need for some 63/37 lead solder low temp. Because im in the uk im really not sure witch to get. Its for ps4 HDMI repairs.Could someone please link me to what i need from rs components because im close to a shop of theres.

author: Nusa
author_rank: Super Contributor
timestamp: February 27, 2020, 09:44:56 am
content: 63% tin / 37% lead only has one melting point: 183°CIf you're looking for a lower temp than that, it can be found, but it's not going to be 63/37 anymore.https://www.kester.com/Portals/0/Documents/Knowledge%20Base/Alloy%20Temperature%20Chart.pdf

author: Gyro
author_rank: Super Contributor
timestamp: February 27, 2020, 09:49:02 am
content: Sure.Go to the RS website. Type in 'Solder' in the search box, and then go down the filters to "Percent Lead" and select 37.It looks as if they stock MBO brand in various diameters from 0.35mm to 1mm. 0.5mm is probably a good compromise for SMD use unless you're applying extra flux.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 27, 2020, 10:53:16 am
content: If it's the low temp you need, you can consider bismuth alloys. They are available in both lead-free and leaded varieties and are sold for soldering. Bismuth alloys are relatively cheap compared to low melting alloys with other metals, like indium or gadolinium.
Leader 120A Signal generator repair question.... - Page 1
Forum section: electronics / beginners

author: Skallywampus
author_rank: Newbie
timestamp: June 14, 2020, 08:03:17 pm
content: This generator shows no recognizable wave pattern....until......Q106 emitter when touched by the + lead of multimeter generates sine waves....let go..no sine wave. Removed jfet..tested good with multimeter.....reinstalled.....same behavior.....stumped. Maybe JFET fail under load?

author: bob91343
author_rank: Super Contributor
timestamp: June 15, 2020, 05:00:38 am
content: A strange take on the old Wien bridge oscillator. I suggest adding a 1 megohm resistor from that emitter to ground.

author: Ash
author_rank: Regular Contributor
timestamp: June 15, 2020, 05:26:34 am
content: Hi,The 'Sync' connection looks suspicious.. A quick glance at the user manaual says the the terminals should have a shorting link across the terminals when that is not in use.. Is that on the back still?https://doc.xdevs.com/docs/Leader/Leader%20LAG-120a%20-%20Manual.pdfPage 3, section 1.3.2 #12.Good luck! Fixing old gear is lots of funAsh.
Leader LPS-163 power supply  - Page 1
Forum section: electronics / beginners

author: Aravinth
author_rank: Newbie
timestamp: December 13, 2020, 12:38:48 pm
content: I'm looking for Leader LPS-163 power supply manual for troubleshooting.I got it from my grandpa.. it was in the storage for about 15 years.When I got my hands on it.. I plugged it in worked great.. I tried to set the cc function shorted the supply leads and it worked for couple of seconds and then it stopped displaying.Someone please direct me to the manual.

author: bob91343
author_rank: Super Contributor
timestamp: December 13, 2020, 09:32:58 pm
content: Did you contact Leader?

author: Doctorandus_P
author_rank: Super Contributor
timestamp: December 15, 2020, 11:30:17 pm
content: Does it look a bit like:https://duckduckgo.com/?q=Leader+LPS-163+power+supply+manual&t=h_&ia=webhttps://static.arantius.com/misc/Leader%20LPS-15x.pdf

author: Aravinth
author_rank: Newbie
timestamp: December 23, 2020, 06:21:43 am
content: I haven't contacted Leader, I dont know if the company still exists.I've attached an image of my power supply. Please let me know if it rings any bell.I can open up the PSU if needed.

author: bji900
author_rank: Contributor
timestamp: February 25, 2023, 09:31:10 pm
content: https://archive.org/details/lps-160-a-1-series-manualLeader DC Power Supply ManualLPS-160A/-1 SeriesModels CoveredLPS-160A, LPS-160-1LPS-161A, LPS-160-2LPS-162A, LPS-160-3LPS-163A, LPS-160-4LPS-164A, LPS-160-5
Leader Oscilloscope question. - Page 1
Forum section: electronics / beginners

author: slowlearner
author_rank: Newbie
timestamp: August 05, 2017, 12:35:14 am
content: Hi,Can anyone tell me if the screen surround can be removed from a Leader LBG-518 scope without dismantling the front panel?I have a cracked protective window that I want to replace but I can't see any way to remove the surround.Thanks,

author: Ash
author_rank: Regular Contributor
timestamp: August 05, 2017, 01:07:13 am
content: Hi,Strangely enough I just took mine off yesterday to clean it.There are 3 screws under the label on top of the screen. If you pull the sticker almost off so it is still attached on an end, it will be easier to fit back in the right place.Then when it comes off, the screen is retained by a plastic besel on the inside that you can carefully pull out. It's secured in the corners with a friction fit lug.There should be a metal spring at the bottom that fits in two little slots that presses on the bottom of the screen as well.Hope that helps.Ash.

author: Ash
author_rank: Regular Contributor
timestamp: August 05, 2017, 02:38:51 am
content: Oh, also I have a service manual for this if you haven't found it yet.Also, I think you mean LBO-518?Ash.

author: slowlearner
author_rank: Newbie
timestamp: August 05, 2017, 12:33:02 pm
content: Thanks Ash,Don't know why I didn't think to check under the label.Glued up the crack, should keep the dust out. It would be nice to replace the screen cover but I doubt that parts would be available.And yes it is an LBOI have found a copy of the service manual, hope I don't need it.Cheers
Leadfree solder with 138ºC melting point - Page 1
Forum section: electronics / beginners

author: ablacon64
author_rank: Frequent Contributor
timestamp: February 24, 2014, 02:18:04 am
content: I crossed by this video and it seems amazing. Anyone using it? Is it reliable?I think it would solve many problems specially with BGA soldering.

author: IanB
author_rank: Super Contributor
timestamp: February 24, 2014, 02:41:31 am
content: As with many things, if it seems too good to be true, it probably is.If you read up on tin/bismuth solder alloys, you will find there are enough downsides that it is not found in regular use.Approach with caution.

author: JuKu
author_rank: Frequent Contributor
timestamp: February 24, 2014, 11:51:43 am
content: As with any soldering procedure, you must get your process right. But when you do, it is as good as other methods. When you go to details, all solders have good and not so good properties. Notable downsides for bismuth alloys have low surface tension, so parts don't self-align as nicely and fall off more easily if doing double side reflow without glue. Also, those used to be expensive and they don't tolerate lead pollution (but you are supposed to keep leaded and non-leaded separate anyway), but those issues shouldn't be problematic nowadays.

author: ablacon64
author_rank: Frequent Contributor
timestamp: February 24, 2014, 01:06:18 pm
content: I could not find many information about what would be the behavior of that alloy on soldering high density (as in small pitch) BGA chips like an AMD North Brigde. What's the thermal expansion, if it's subject to cracks, etc...One of the bigger problems I find when reworking BGAs is leadfree high temperature. I guess it would be really nice to have such a low melt point solder.
Leakage Current - Page 1
Forum section: electronics / beginners

author: ganshulrao
author_rank: Newbie
timestamp: October 24, 2013, 11:10:56 am
content: Hi,what is the expected LEAKAGE CURRENT at 60Kv DC for a Low Density Polytheylene (LDPE) insulated Cable?Conductor - 7mm OD (Copper), Insulation 23mm ODNot sure if this is the right forum.If not are there any other forums where I could post this.thank you

author: madshaman
author_rank: Frequent Contributor
timestamp: October 24, 2013, 12:53:32 pm
content: Hi, your question seems difficult to answer without more information.e.g. what's the return path through the insulation?I'm a bit frightened for you dealing with 60KV and being unsure about this question. Hope someone can help.

author: Bertho
author_rank: Regular Contributor
timestamp: October 24, 2013, 01:37:58 pm
content: That depends on the environment.If you run it in free air, then the leakage will be quite small to none (depending moisture). The biggest loss will probably come from potential corona effects if you have any part of the connection exposed to free air.The actual isolation properties are very good for LDPE and the dielectric strength is ~27kV/mm. But, it can take in 0.01% water, which means that the environment can partly destroy the isolation properties.

author: Zero999
author_rank: Super Contributor
timestamp: October 25, 2013, 05:49:57 pm
content: I agree with the above but you can calculate the worst case.Volume resistivity 1016Ohm·cmhttp://en.wikipedia.org/wiki/Linear_low-density_polyethylene

author: Bertho
author_rank: Regular Contributor
timestamp: October 25, 2013, 06:17:18 pm
content: Just one other note.If you run the cable next to a grounded plane or any part that connects to ground, but still with some distance, then you may have a capacitive problem. The LDPE isolation will then form a series capacitor where the first is from the core to the outside (with the LDPE as first dielectric) and the second capacitor is the air as dielectric.The problem is that LDPE has a dielectric constant of 2.3, whereas air ~1. The voltage from the core to the ground-plane will distribute inverse proportional to the capacitance. That pulls quite a strong electric field over to the air-gap. With only 3kV/mm isolation in air, you can have sparks flying quite easily.As example: LDPE cable uses 5mm isolation. if you have 10mm air to a ground-plane, then the effective capacity of both LDPE and air are about the same, which would let 50% of the 60kV drop over air, which only can withstand 30kV at that distance. Thus sparks may fly if there is just a very small amount of moisture.Your cable should be clear from all grounded surfaces byat least20mm to be on the safe side. Better would be about 50mm.
Leakage inductance of a  variac - Page 1
Forum section: electronics / beginners

author: MarkoAnte
author_rank: Regular Contributor
timestamp: November 28, 2016, 05:46:21 pm
content: Does anybody know if the leakage inductance variac changes in relation the the wiper location, if the variac is wound on a toroidal core? If it was 2 different windings then it would, but if it is the 1 winding can we still look at it as a separate one and say that the leakage inductance does increase if we have the variac set to 10% instead of the 100%.Best regards,Marko

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 29, 2016, 01:37:44 am
content: With respect to what? You have three choices: primary (total winding), secondary (wiper to neutral), and upside-down (wiper to hot).In any case, taking a consistent comparison, the leakage won't be much worse in one position than any other, though I expect it will be minimal in the middle, and maximal towards the ends (following a gentle parabolic curve inbetween). I would think the difference to be small, perhaps 20%.(I think the "consistent" method would be, one half (hot to wiper) with respect to the other half (wiper to neutral), adjusted for turns ratio. This uses it as a normal transformer (that happens to have a common point tied between the two windings), so the measured value is reasonable with respect to regular transformers.)I wouldn't expect it to be very useful at frequencies over a few kHz, if that's what you're thinking..?As an autoformer, the output current capacity (including surge/fault capacity) and regulation (series equivalent impedance) are quite good. Most pronounced for high ratios (above, say, 25%), you get the divider effect in addition to the transformer effect, or in other words, a lot of output current flows in series through the top half of the winding, as well as being sourced from the bottom half of the winding. Of course, at ~100%, all the current is sourced from the hot wire, and there's no series impedance. (You're still limited in current by the size of the wire, of course.)Tim

author: MarkoAnte
author_rank: Regular Contributor
timestamp: December 04, 2016, 11:28:19 am
content: Ty for the replay. I found a book that showed what you are talking about (the parabolic curve etc.) No few kHz here, I have to write up a report for a university course and then we have to comment on some results and I didn't know if this would be a factor or not.Regards,Marko
Leakage through isolated linear supply causing MAX31855 error? - Page 1
Forum section: electronics / beginners

author: ledtester
author_rank: Super Contributor
timestamp: October 15, 2020, 03:48:33 am
content: I'm using a LM317 to heat a heatsink. Attached to the heatsink is a K-type thermocouple which is being monitored by a MAX31855 module (ebay variety) and a Teensy. The Teensy is powered via USB.I didn't use a thermal insulating pad on the 317 -- after all, I want it to heat the heatsink. I've noticed that if I connect a lead from my linear power supply to the 317 (either positive or negative) the temperature readings are way off -- even with no power applied and the power supply switch off.I know the MAX31855 needs to be isolated. I guess though that my isolated linear power supply isn't isolated enough. I'm wondering what exactly is going on.

author: ledtester
author_rank: Super Contributor
timestamp: October 15, 2020, 04:45:29 pm
content: Well, I figured out something - apparently it was my ethernet cable.Powering the laptop via mains vs. battery didn't make a difference, but the reading error went away once I unplugged my laptop's ethernet cable.
Leakage  - Page 1
Forum section: electronics / beginners

author: Brainfarth
author_rank: Newbie
timestamp: July 27, 2015, 02:08:44 am
content: I threw together a bluetooth speaker with some junk laying around and ran into an odd problem. With the switch off, I'm getting enough voltage to light the LED on the amp. I would rather not have to install two power switches. Attached to this message is my rendition of the wiring.

author: SL4P
author_rank: Super Contributor
timestamp: July 27, 2015, 02:19:50 am
content: Voltage to the amp between the top rail, and the 7805 (floating at top rail minus 4 cells)

author: w2aew
author_rank: Super Contributor
timestamp: July 27, 2015, 03:10:17 am
content: Change to DPST or DPDT?

author: Brainfarth
author_rank: Newbie
timestamp: July 27, 2015, 03:44:10 am
content: The rocker switch that I'm using is a single. I was hoping that someone had an elegant solution. I have a pile of components laying around and could possibly throw something together. But unfortunately, I don't have any relays.

author: Monkeh
author_rank: Super Contributor
timestamp: July 27, 2015, 03:46:38 am
content: Put a diode before the regulator.

author: BradC
author_rank: Super Contributor
timestamp: July 27, 2015, 03:50:22 am
content: That configuration is going to create quite the imbalance across your batteries. You'll need to look at that when you charge them also.

author: Brainfarth
author_rank: Newbie
timestamp: July 27, 2015, 04:12:25 am
content: The regulator is a L7805CV from china. Do you think it would hold up very well against a max of 18v input? The bluetooth receiver hardly draws anything. If that's the case, it would solve the rest of my issues.

author: BradC
author_rank: Super Contributor
timestamp: July 27, 2015, 04:16:13 am
content: Quote from: Brainfarth on July 27, 2015, 04:12:25 amDatasheet says 35v.

author: Brainfarth
author_rank: Newbie
timestamp: July 27, 2015, 05:26:22 am
content: I guess the only reason I questioned the higher voltage is that I've heard that they get very inefficient. Or is this not going to be an issue because the bluetooth receiver draws such a small current?

author: BradC
author_rank: Super Contributor
timestamp: July 27, 2015, 06:09:36 am
content: Quote from: Brainfarth on July 27, 2015, 05:26:22 amThat depends entirely on exactly what "small current" means and it's entirely relative. A couple of 10's of milliamps and you'll be fine, much more than that and you'll want a heatsink. Why not buy one of those $2 buck converter boards from China and have it both ways?
Leaked alkaline battery and wire replacement - Page 1
Forum section: electronics / beginners

author: doodle43
author_rank: Newbie
timestamp: April 23, 2023, 08:57:12 pm
content: I have a controller for a toy drone that sat too long and the alkaline batteries leaked. I cleaned the battery compartment with vinegar. But I can see what I presume to be the same battery acid corrosion on the black wire and terminal on the PCB. It looks like the battery acid went through the black wire. I assume this will need to be completely replaced, but I’ve only ever soldered once and never done a wire.Do I need to clean the remaining battery acids with vinegar and then desolder and solder on a new wire? Should I replace both wires?

author: BeBuLamar
author_rank: Super Contributor
timestamp: April 24, 2023, 02:57:06 am
content: Definitely clean all all the chemicals from the battery. You can replace the wire but it looks like you don't need to.

author: james_s
author_rank: Super Contributor
timestamp: April 24, 2023, 07:07:32 am
content: It's not acid, it's alkali, that's why vinegar (acid) works to neutralize it.It does look like the corrosion has gone all the way up the wire, you might get away with just cleaning the crud at the ends though.

author: tooki
author_rank: Super Contributor
timestamp: April 24, 2023, 11:11:57 am
content: Replacing the wire is so easy I would do so anyway. Just practice with some scrap wire and scrap PCBs before attempting the repair.

author: james_s
author_rank: Super Contributor
timestamp: April 25, 2023, 01:08:49 am
content: It might not be that easy actually, when the battery corrosion strips off the plating it can be quite difficult to solder a wire to it, especially if the contacts are made of steel or something instead of copper. When you combine that with the terminals being in plastic that melts easily it could end up being pretty frustrating for a beginner.If you do end up replacing the wire, I would use a wire brush on a rotary tool to really clean it up nice before trying to solder it.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: April 25, 2023, 03:02:38 am
content: The other day I used 3% H2O2 diluted about 10:1 with distilled water to successfully clean a battery leak. Worked well. Just said WTF and tried it.
Leaning electroncis by teaching (YA) - Page 1
Forum section: electronics / beginners

author: Youkai
author_rank: Regular Contributor
timestamp: March 01, 2020, 07:01:33 pm
content: Hey guys, Youkai's Artificery (YA) here. I'm starting a twitch/youtube where I build cosplay/video game props, especially ones that use 3D printing and electronics. The EEVBlog forum has been a tremendous help with my current project. Getting help with the schematic though doesn't help me understand why I made the changes that were recommended. So I thought I would make some "learn electronics" youtube videos and do the time honored "learn by teaching" method.I saw this post on reddit recently:https://www.reddit.com/r/electronics/comments/fbcv64/a_very_simple_usb_cable_5v_led_testing_circuit/and I thought that little projects like this would be the perfect way to learn/explain things like current flow, etc. I'd like my learn electronics videos to be made of things like that so that they are more fun than simple "lets learn how resistance works" type things.So I'm looking for a few things here.First, any links you might have to similar projects like the reddit one which are simple and could be used to demonstrate/explain either concepts in electronics or how specific components work (potentiometers, NeoPixel LED's, etc.)Second, even if you don't have a link to an explanatory project; any concepts/components you think would be important for beginner/intermediate people to learn. I don't know if it's a beginner thing but for example in my current project someone recommended a BAT54S before my NeoPixel. I really don't understand why that's in the circuit, other than it helps prevent the NeoPixel from blowing out. So that is something I'll probably plan on covering in a video.Third, I'll be learning these things as I build the videos for YouTube so I'm definitely going to need some help learning the concepts and checking my scripts. What would be the proper place to put a thread for that purpose? Is "Projects, Designs, and Technical Stuff" the correct place?If you are interested about my current project here is my build log document:https://docs.google.com/document/d/1UCf8qaZgw3GsMXFvT55gbCp3WXba2CDr0ZiEJwghIu4/edit
learn-fpga: an amazing resource for FPGA, RISC-V in 100 lines! - Page 1
Forum section: electronics / beginners

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: August 29, 2023, 10:28:28 am
content: https://github.com/BrunoLevy/learn-fpga/blob/master/FemtoRV/TUTORIALS/FROM_BLINKER_TO_RISCV/README.mdAbsolutely amazing tutorial for beginners like meI kind of miss some testing, but the test-as-you-go feels familiar and nice for small projects.Worth a read for those interested in - and curous about FPGA.
Learn rtos - Tiva board - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: January 14, 2015, 03:04:30 pm
content: 1. I want to learn RTOS with TI's TM4C board. I use Keil.2. I had searched on net & checked that freertos is used very frequently.3. What is best way to learn freertos. (I have to learn to basic of rtos also)There is book on freertos website, is it right place to start?Or any suggestions for that.

author: dannyf
author_rank: Super Contributor
timestamp: January 15, 2015, 12:27:08 pm
content: QuoteBased on your other posts, I think you can do yourself a big favor by learning the basics, like how to use your tools, how to code, how to blink a LED, etc."Learn to walk before you try to run", as some wisemen said.Good luck in whatever you are doing.
Learn  VHDL or Verilog for Power Electronic applications? - Page 1
Forum section: electronics / beginners

author: Dmeads
author_rank: Regular Contributor
timestamp: June 04, 2019, 11:58:29 pm
content: Hello!I am interested in doing power electronics projects on SoC type chips and FPGAs. I want to do things like PWM, SPWM, Motor control, and simulate in real time using MATLAB/Simulink.I am trying to learn verilog right now, and its going pretty well considering I have never taken a digital logic course.The lecture Im watching on youtube said VHDL was designed for system design(high level), where as verilog was design for easy use with gate level design.I don't have a ton of time right now, so would it be better for me to learn VHDL or Verilog for the projects im working on?I have a tiny tiny bit of coding experience in MATLAB and Arduino but thats it, so its not like i would pick Verilog up easier due to it's c like nature.Thanks!

author: rstofer
author_rank: Super Contributor
timestamp: June 05, 2019, 01:43:18 am
content: You're just going to start a language war!If you understand Verilog (and I don't), then use it! I started with VHDL so of course I'm going to say it is the best thing since sliced bread (it isn't). But I have no real justification for selecting one over the other.Some will say they hate the verbosity of VHDL, others will like it because the language is strongly typed. And round and round it goes.Just watch!

author: OwO
author_rank: Super Contributor
timestamp: June 05, 2019, 05:17:08 am
content: VHDL and System Verilog are both fine languages to use, just whatever you do avoid plain old verilog like the plague.
duplicate post plz delete - Page 1
Forum section: electronics / beginners

author: Electro Fan
author_rank: Super Contributor
timestamp: May 31, 2020, 05:29:13 am
content: duplicate post - tried to delete - sorry

author: sairfan1
author_rank: Frequent Contributor
timestamp: June 02, 2020, 04:17:50 pm
content: I believe if post has no reply yet, user should has option to delete it, or user should has option to mark post as deleted and later some admin look on it and delete.

author: Electro Fan
author_rank: Super Contributor
timestamp: June 03, 2020, 12:09:10 am
content: This message comes up when trying to delete....An Error Has Occurred!You cannot delete your own topics in this board. Check to make sure this topic wasn't just moved to another board.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 03, 2020, 12:35:58 am
content: Quote from: sairfan1 on June 02, 2020, 04:17:50 pmno cant. only mod can delete a thread... like this one that i cant delete...https://www.eevblog.com/forum/beginners/programming-max3949-laser-driver-ic/msg3002668/#msg3002668(hope mod looking at this can delete that thread as well) so if you want to make a thread, think 5 times first before posting...
Learned something about fuses today - Page 1
Forum section: electronics / beginners

author: Skyfox
author_rank: Regular Contributor
timestamp: February 05, 2017, 01:58:38 pm
content: I have to say, finding certain specifics about fuses and other components can be a real pain sometimes!Yesterday I found a ceramic tube fuse that turned out to still be good, so I figured I'd look up the specs on it to know what it is. Here's the info on the end cap (as I first read it and searched for it):side: H250VF3.15Aend: Littlefuse logo and Semko mark(the end of the other cap has the BSI [British Standards Institute] kitemark, and the side is blank)Since the A ran right into the H I thought maybe the part number started with AH. In reality, I was confusing myself because when I did the part search I duplicated it by looking for AH250V3.15A, and of course very little came up, and then I realized the error and searched without the extra A. But 3.15 amps seemed a bit obscure, so I thought it was a 15 amp fuse and F3 was some kind of product code.I looked up the Littelfuse datasheets and fuse catalog, eventually finding ceramic fuses of this size, in the Littelfuse series 215 (slow-blow) and 216 (fast blow). My guess was that the F may mean fast, but neither datasheet describes how to decode the markings on the side of the fuse cap. They listed how to read the part number when you order a reel of fuses or something. It was the same when looking up these fuses in Digikey or Mouser because neither site showed that specific string of characters on the part pages and the datasheet links referred right back to the ones I already read.I finally had a break when I noticed there was a slight misalignment between the V and F. So I did a search for F3.15AH250V, and there it was! I learned that the letters and numbers on the side of the fuse are called the IEC markings (International Electrotechnical Commission). What came up brought me to the specific page on Littelfuse's page for this exact fuse which listed that IEC marking exactly as it shows up on the cap. Turns out, the F does in fact mean fast blow, while it it was a slow-blow it would be a T for timed blow. If I'd read the catalog more thoroughly it would have told me about that. And the H stands for high breaking capacity. They should include the IEC marking in the datasheet.And it only took 45 minutes!
Learning about Operational Amplifiers - ADALM1000 & ADALP2000 Kits by Analog De - Page 1
Forum section: electronics / beginners

author: ozwolf
author_rank: Regular Contributor
timestamp: September 29, 2015, 12:01:58 am
content: G'day!I came across thishttp://www.rs-online.com/designspark/electronics/eng/blog/initial-experiences-with-the-adalm1000by ChelsiaBack on DesignSpark . She's done a follow up posthttp://www.rs-online.com/designspark/electronics/eng/blog/learning-about-operational-amplifiers/?utm_source=newsletter&utm_medium=email&utm_content=date:%2028/09/2015&utm_campaign=operational_amplifiers.She's discussing the active learning modules by Analog Devices.Dave has sparked my interest again on analog circuits and I think this may be a reasonable self paced learning experience.Anyone have any thoughts on this system?Ozwolf
Learning about PCB design - Page 1
Forum section: electronics / beginners

author: cmumford
author_rank: Contributor
timestamp: October 20, 2020, 01:20:20 am
content: Are there any good references to learning about good PCB layout and design? I've learned (or learned of) a few things, like distance between I2C traces, track width for current, differential pairs, but I'm sure there is WAY more to learn, and probably tons of bugs in my design. Is there a good online reference? Any good book references?