hybridfree/eevblog-posts huggingface dataset:
Is it time to replace my iron tip when? - Page 1
Forum section: electronics / beginners

author: mictas
author_rank: Regular Contributor
timestamp: December 06, 2017, 08:04:59 am
content: So, a few days ago I was trying to do some soldering and I found my iron tip just not cutting it. After taking off the tip its self, I have notice that an inner sheath hanging loose and easily removable. This is sitting between the heating element and the tip itself.I did notice that the iron works fine with another tip. And I was always thinking it a tip had to be in real bad shape, before it needs replacement.By the way, I have a Hakko FX888D soldering station.

author: AndyC_772
author_rank: Super Contributor
timestamp: December 06, 2017, 08:27:17 am
content: Any tool that is no longer doing the job it's required to do, should be repaired or replaced.Tips are cheap and disposable. Change it.

author: Rerouter
author_rank: Super Contributor
timestamp: December 06, 2017, 09:02:37 am
content: That sheath you have noted is the ceramic casing for your irons heater. If it has cracked, you will have to replace the heating element. And this loose fitting cracked heater would be why it's not performing up to snuff.For hakko stuff you may find buying an entire new pencil is fairly cheap.

author: mictas
author_rank: Regular Contributor
timestamp: December 06, 2017, 11:35:35 am
content: Quote from: Rerouter on December 06, 2017, 09:02:37 amThere are no cracks in the ceramic, I make sure to check that, every time I have swapped the tip. It has some black lines on it, but it looks in-tacked.Its more the inner sleeve on the iron tip, the metal sheath came off very easily and I am thinking... "Okay, that is not good"
Is it totally safe to short an open drain output of an IC to ground? - Page 1
Forum section: electronics / beginners

author: mbmsv
author_rank: Newbie
timestamp: January 05, 2024, 10:45:47 pm
content: Let's say I have a design that controls some active low output signal using an open drain output and I want to provide an option for a user to force this signal to low. Can I simply add a jumper between my output and ground? The pull-up resistor is a part of my circuit, so I know that the current through the jumper will be small. Thanks.

author: Benta
author_rank: Super Contributor
timestamp: January 05, 2024, 10:55:24 pm
content: Yes. That's what open-drain outputs are for.
Is it true that increasing winding count doesn't increase electromagnet force? - Page 1
Forum section: electronics / beginners

author: dusan
author_rank: Regular Contributor
timestamp: February 28, 2024, 10:23:42 am
content: The formula for the pull force of electromagnet is:Code:F = (N x I)^2 x μ0 x A^2 / (2 x g^2)N=number of windingsI=currentA=areag=distance to metalHowever if I increase number of windings, the resistance will increase linearly so the current will proportionally drop (if I keep voltage the same, e.g. battery). So if I increase the number of winding using the same wire it will not increase the pull force. Correct?

author: radiolistener
author_rank: Super Contributor
timestamp: February 28, 2024, 11:28:07 am
content: Yes, increase winding count leads to more longer wire which increase it's resistance, but you can increase voltage in order to keep current the same and get higher magnetic field strengthAlso note that magnetic filed strength depends on current I (Amperage) and winding density (N loops count per L distance):\$H = \frac{NI}{L}\$So, there are two way to increase magnetic field strength - increase current or/and increase winding density. You can increase winding density by increasing loops count with keeping the same coil length or by reduce coil length with keeping the same loops count.Both ways has some limit because wire has some diameter and you're needs to decrease wire diameter in order to bypass size limit which is also leads to increase wire resistance.

author: donlisms
author_rank: Frequent Contributor
timestamp: February 28, 2024, 06:06:44 pm
content: And remember - there are constant current supplies as well as constant voltage supplies.

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 28, 2024, 07:16:24 pm
content: Increasing number of windings would likely to increase magnetic force strength because the added resistance usually not very much if you use decent wire size.
solved: Is lead free HASL okay for 0402 resistors and 0.5mm QFN-48? - Page 1
Forum section: electronics / beginners

author: incf
author_rank: Frequent Contributor
timestamp: March 28, 2025, 08:38:42 pm
content: "Is lead free HASL okay for 0402 resistors and 0.5mm QFN-48?"At what point is HASL too bumpy to allow assembly of small SMT components? Can 0201's be compatible with HASL?It seems like it can vary a lot.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: March 29, 2025, 02:53:07 pm
content: Lead-free HASL is not ideal for 0402 resistors.https://www.acdi.com/comparing-pcb-surface-finishes

author: wraper
author_rank: Unknown
timestamp: March 29, 2025, 02:58:52 pm
content: It depends, if it's a good HASL, it will be fine. But HASL often is way too bumpy for that. If it's for production, for cost saving use OSP instead.
Is LTSpice an appropirate tool to use to model digital circuits? - Page 1
Forum section: electronics / beginners

author: JoeN
author_rank: Frequent Contributor
timestamp: August 10, 2016, 05:45:40 am
content: By digital circuits, I mean transistor circuits working as digital circuits where the circuit is modeled up from transistors up to gates, more complex subcircuits, and finally state machines. Right now I modeled a RS flip flop and built a test circuit to use it as a frequency divider, just as a test. I think it is quite interesting how as an analog simulation it shows you the slew of the transistors (especially when it is run at a faster clock), voltage excursions, etc. Is this the way to do it? Or is this insane? How well is this going to perform if there are a few thousand transistors in the simulation?Comments or advice would be appreciated.Basic gates:Inverter2-NAND3-NANDThe RS flip flop:The testbench circuit:The results:

author: bobaruni
author_rank: Regular Contributor
timestamp: August 10, 2016, 09:57:53 am
content: Looks good and if it works for you, why not!Simulations will start to slow down the more components and signal paths you have.Also, there are a few digital gate components built into LTSpice's shipped library.I just wonder though, if you are going to design something using thousands of transistor, it might be time to look at something like CPLD/FPGA.

author: rstofer
author_rank: Super Contributor
timestamp: August 10, 2016, 01:33:26 pm
content: Or at least use the toolchain for the CPLD/FPGAs. Most have schematic entry and many have simulators. There's a bit of a learning curve to using the toolchain and describing circuits but they can be described at the gate level.Try the free version of Xilinx Vivado.
Is Micsig DP10007 Differential probe suitable for SMPS work - Page 1
Forum section: electronics / beginners

author: sijmen
author_rank: Contributor
timestamp: August 11, 2021, 10:10:57 pm
content: Hi,I'm looking for a Differential probe that can be used for SMPS work. Originally I was looking at the HVP70, but they're not in stock, so then thought of the Micsig DP10007, but I'm not sure if the 700v max input is good enough for SMPS voltages. (230V mains input).Links to the specs are below:For the HVP70:https://www.eevblog.com/product/hvp70/For the Micsig probes:It seems to me the HVP70 is more closely matched the to DP10013 than the DP10007, but would like clarification, and what are the key specs I should be focusing on.I'd also like to know if the DP10007 could be used for SMPS work.Regards,Sijmen.
Is my AFCI breaker bad or is it supposed to do it? - Page 1
Forum section: electronics / beginners

author: BeBuLamar
author_rank: Super Contributor
timestamp: November 28, 2023, 05:02:27 pm
content: I wired up a small power supply with 3 terminals, L, N and GND. To make sure that I have the L and N wired correctly I measured the voltage between the L and GND to make sure it has voltage. I used a Fluke 113 with has low Z voltage input. So when I did that it trip the AFCI breaker. Is the breaker supposed to do that or is it to sensitive?

author: CaptDon
author_rank: Super Contributor
timestamp: November 28, 2023, 05:24:56 pm
content: How low is low Z?? If it created a current of over 5 ma. it would probably trip. I think that would trip even a standard GFI?

author: coppice
author_rank: Super Contributor
timestamp: November 28, 2023, 05:32:52 pm
content: Quote from: BeBuLamar on November 28, 2023, 05:02:27 pmDid you mean AFCI? This is more the behaviour of a GFCI. Those low Z voltage measurement functions will trip a sensitive GFCI.

author: CaptDon
author_rank: Super Contributor
timestamp: November 28, 2023, 05:36:50 pm
content: AFCI will still trip just like a GFI, it combines both functions.

author: bdunham7
author_rank: Super Contributor
timestamp: November 28, 2023, 05:40:02 pm
content: Quote from: BeBuLamar on November 28, 2023, 05:02:27 pmAccording to this, a Square-D AFCI willl trip by 50mA. Your 113 has about 2.2k initial impedance IIRC, so at 170Vpkyou'll definitely be over 50mA.https://media.distributordatasolutions.com/schneider2/2020q3/documents/494f6c69f2d3d986959417d7a8b1bdfc64bcb40a.pdf
Is my beaglebone black wireless busted? - Page 1
Forum section: electronics / beginners

author: Dijital
author_rank: Contributor
timestamp: January 15, 2017, 05:22:36 am
content: I cannot find an answer to this anywhere.If you take a bbb wireless out of the box, plug in an hdmi and plug in a power cable, is it supposed to boot into linux? It seems like it ships with a linux distro already flashed, but I can't find any sign of it. My 1080p monitor just shows a black screen, no noise, flickering, or anything. The pamphlet in the box seems to imply it should, but the "getting started" tutorial says nothing on the matter.I tried flashing the latest kernal but the bb just seems to hang and never finish (i left is flashing for 6 hours). Also the wiki gives linux commands to adjust in ordere to force it to flash on boot, but without any sort of video output, im not sure how I am supposed to edit the settings. I'm usually pretty technically adept, but this thing has got me stumped.

author: rstofer
author_rank: Super Contributor
timestamp: January 17, 2017, 02:22:30 pm
content: You didn't mention the microSD card. In theory, BBB boots from the microSD. There used to be a time when they would flash the image but it bricked too many boards. Read about it here:https://beagleboard.org/latest-images

author: sam1275
author_rank: Frequent Contributor
timestamp: January 19, 2017, 01:16:36 pm
content: Do your bbb have heartbeat/CPU/MMC LED?I have a no-wireless bbb, and I didn't try HDMI yet, but it boot well, it response to USB and Ethernet by default, and flash a new firmware takes about 10 minutes I remember.Good luck.
is my counters cal ok? - Page 1
Forum section: electronics / beginners

author: ME
author_rank: Frequent Contributor
timestamp: September 07, 2025, 08:47:30 pm
content: I have an old Blackstar meteor 600 counter , i fed it 10MHZ from my bh3sap GPSDO The call cap is very finiky , the nearest reading i can get with a 10 second gate time is 10.000005 ,iss that ok , It is used at hf and below mostly but maybe 2m if its ok for that?.

author: DimitriP
author_rank: Super Contributor
timestamp: September 07, 2025, 09:26:22 pm
content: Feed the 10MHz signal to the external REF input if yours has one.You'll have more variation due to temperature than the calibration accuracy.It's close and good enough for HF and 2m @ 0.5ppm.

author: radiolistener
author_rank: Super Contributor
timestamp: September 08, 2025, 06:28:18 am
content: 0.5 ppm is good result for amateur purposes, for better result it requires some cesium or rubidium frequency standard, its more expensive and hard to calibrate for amateurs.

author: ME
author_rank: Frequent Contributor
timestamp: September 08, 2025, 11:15:57 am
content: now all i need to do is check my wavetek si4015 gen output with it,as i cant find a way to do it as the user manual is crap and written by aliens! for the si4015.
Is my flowchart for programmed io and interrput drive io correct? - Page 1
Forum section: electronics / beginners

author: shivajikobardan
author_rank: Contributor
timestamp: October 22, 2021, 01:39:29 pm
content: Source of my knowledge-:https://electronics.stackexchange.com/questions/204337/programmed-io-vs-interrupt-for-deviceshttps://slideplayer.com/slide/265620/And my teacher.So here is what I understand about1) Programmed IO-:Here CPU periodically executes instruction which reads READY pin2) Interrupt driven IO-:Here CPU checks interrupt at the end of each instruction cycle whereas IO device sends interrupt.The original flowchart for these are as follows-:https://imgur.com/a/fIwwxyfHere is what I have made-:https://imgur.com/a/0woBT73First one is programmed io and second one is interrupt driven io. In interrupt driven io I mistakenly drew arrow from "CPU issues read command to IO module" to "hardware/CPU checks for interrupt at the end of each instruction cycle".I just want to know if my understanding of flowchart is correct or not?

author: westfw
author_rank: Super Contributor
timestamp: October 24, 2021, 11:42:48 pm
content: I would say that in Programmed IO, the SOFTWARE issues a read command to the IO device and checks the ready pin, while with interrupts the CPU Hardware checks for interrupt after each instruction. And I don't like that in the original diagram ends the interrupt by going to the top, instead of with a "return from interrupt" - I would draw the whole "interrupt" routine as disconnected from the main program flowchart. (but that doesn't agree with your textbook, so it might not be the answer that they want.)
Is my Li-ion battery still safe to use? - Page 1
Forum section: electronics / beginners

author: sam1275
author_rank: Frequent Contributor
timestamp: December 06, 2016, 02:37:50 am
content: Hello.Today I teared down my tablet, the battery is consist of 2 pieces of thin, large surface area and soft cell, they stick to a metal plate using some double-side glue tape, so I have to pull real hard to get it off, during this I bent the battery, then I bent it back. The area I bent went warm for a while, then cooled down, now the battery still seems to work, but is it still safe to use?Thanks.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 06, 2016, 03:43:03 am
content: It never was completely safe, and now is less safe than before.I wouldn't use it unless I was prepared to deal with a battery fire. Meaning easy and fast access to a ventilated and fire resistant space to dump the entire laptop. The hidden message is that you have to be ready to sacrifice the laptop to continue using it.Is this an appropriate risk to take? I can't tell you, and I doubt that anyone else can. I don't know if the chances of a fire are 1 in 10 now or one in a million. It is probably better than 1 in 10 based on my experience with damaged batteries. It is probably not much better than one in a million because the statistics seem to show that undamaged batteries are not more than 10 to 50 times better than that. And even if I could put an exact number on the risk I don't know how you feel about that number. Everyone has different risk and value standards.

author: tatus1969
author_rank: Super Contributor
timestamp: December 06, 2016, 04:53:01 am
content: +1 dont use it anymore, too dangerous. plus discard it quickly and appropriately, it doesnt need to be charged to be able to self ignite.

author: sam1275
author_rank: Frequent Contributor
timestamp: December 06, 2016, 06:37:39 am
content: Okay thank you everyone.That battery is not usually user replaceable, it's inside the tablet and it's just bare cell connects directly to the mainboard, that's why its soft.However you guys should be right, I'll stop using it...
Is my oscillator analysis method in SPICE valid? - Page 1
Forum section: electronics / beginners

author: Whales
author_rank: Super Contributor
timestamp: January 12, 2021, 09:45:39 am
content: I've been investigating Vackar oscillators on my workbench and in my spice sims (QUCS and Micro-Cap). Take for example this triode powered oscillator from figure 5 ofVackar's 1949 paper:My initial buildup looks approximately like this:I promise the diagrams are identical, I've just re-arranged things and added a (slightly off) bias voltage for my mosfet.Previously I used transient analysis in my SPICE sim to see how oscillators behaved, but this was fiddly and time consuming. I realised I could probably get most of the information I needed by running an AC simulation instead.Method 1: Substituting the mosfetReplace the transistor with a sine voltage source (ie Vds = input to control, Vgs = output to measure)Look for a peak in my gate voltage versus frequency graph indicating where the circuit resonates (and therefore may oscillate)Sweep the values of my variable capacitor so I can see different target oscillation frequencies (peaks in my graph).Question:is this analysis technique valid, or am I making some bad assumptions here?Method 2: Adding an AC signal in series with the transistorI thought keeping the transistor itself in the loop would make more sense, ie analyse the oscillator as a whole (not just as a network of RLC). (EDIT:) It seems to resonate much more sharply, floor at 0V and has an odd resonating point low down, making me think I'm doing something silly:Playing with the MOSFET bias doesn't seem to improve this, only make it worse.

author: Whales
author_rank: Super Contributor
timestamp: January 12, 2021, 09:54:51 am
content: Misc note: I've been playing with two different pieces of SPICE sim software, QUCS (as shown above) and Micro-Cap. Both give identical results for AC analysis of the same RLC circuit (hooray!) BUT qucs is about 10x or more faster doing it! Same number of points and everything, it's amazingly better. The results do diverge however if I add the 2n7000 in, but they probably have different models of its parasitics/etc so that makes sense.Both Micro-cap and QUCS seem to have a long list of interface annoyances unique to them both, so I hate them both equally now

author: Ian.M
author_rank: Super Contributor
timestamp: January 12, 2021, 12:48:09 pm
content: See Michael Tien's method for plotting the loop gain of a SPICE simulation.You'll find a reasonable introduction at:https://sites.google.com/site/frankwiedmann/loopgainIt helps if you can run LTspice as that comes with a Tien method loop gain example.
Is my power-adapter universal? - Page 1
Forum section: electronics / beginners

author: paxmees
author_rank: Newbie
timestamp: January 11, 2017, 07:14:49 pm
content: I have an item(Roland sc-D70) with 100 V marking on it. Id like to use it on 230 V line.So I opened it and found:Poweradapter on separate board. (KPC 1694V-0)It has fuse T2AL250V.Cap 400V.Heatsinked 3-leged thingiQuoteCan i asume its safe to use or is there something more i should look?Marking KPC 1694V-0 seems to be more universally used, what is it?

author: CJay
author_rank: Super Contributor
timestamp: January 11, 2017, 09:03:46 pm
content: I'd expect it to have a range like 100-240V rather than a single voltage if it was universal.

author: neil t
author_rank: Regular Contributor
timestamp: January 11, 2017, 09:56:15 pm
content: I wouldn't assume anything, a quick check on google reveals only that it seems to be used by a number of different company's ie Samsung and the like but found no specs or any info relating to voltages.

author: wraper
author_rank: Unknown
timestamp: January 11, 2017, 10:45:39 pm
content: As it is marked 100V, most likely, it accepts 100V only. No other useful information provided in the post.
Is my power supply safe or not? - Page 1
Forum section: electronics / beginners

author: pinipon
author_rank: Newbie
timestamp: September 09, 2014, 11:52:59 pm
content: Hi guys,I'm newbie in EEVblog forum. I would like to have your feedback about my "Chinese" power supply.I bought this stuff 1 month ago and I decided to check some parameters/specs of the device:Although the precision in DC is enough to me, on the adjustable output I can measure 80Vac rms between +/GND and same between -/GND. On the 5VDC fixed output I can measure 50Vac rms. Both 50Hz...My question is: is that stuff safe or not?? or is an issue of the manufacturer... Do I have to claim to the store where I bought this stuff?Please see the pictures at:https://www.dropbox.com/sh/ur99hk7cr8j6kds/AABXGCBb7qvm_AcoeBZFekFYa?dl=0Thanks in advance for your help.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 10, 2014, 12:29:55 am
content: That's normal.What matters is, how much AC current? It's dangerous if it's more than 5mA or so (under 1mA would be preferable).Tim

author: Simon
author_rank: Unknown
timestamp: September 10, 2014, 06:00:02 am
content: put a 1K resistor in parallel with your meter and retry. I can get tens of volts off house walls if i use my meter with about 1Gohm input resistance

author: TriodeTiger
author_rank: Regular Contributor
timestamp: September 10, 2014, 11:22:16 am
content: Either coupling from the transformer, or a cap across the transformer for RFI?, and probably very low current. I thought it in series halved the voltage however, but 80*2 seems like an odd voltage.

author: amyk
author_rank: Super Contributor
timestamp: September 10, 2014, 01:35:08 pm
content: Quote from: TriodeTiger on September 10, 2014, 11:22:16 amInput impedance.

author: pinipon
author_rank: Newbie
timestamp: September 10, 2014, 11:04:53 pm
content: I put 1k resistor between - and GND and take only 40mV rms, current below 0.05mA that's the minimum the meter can measure. Same between + and GND.I do same tests with my home made power supply with initially I take 16Vac rms, but putting a load make the voltage drop to an insignificant value.Thanks guys for your help.Cheers,Pinipon

author: Simon
author_rank: Unknown
timestamp: September 11, 2014, 05:53:27 am
content: if you just touch your meter probe you can pick up well more than 40mV from thin air
Is my resulting transformer correct? - Page 1
Forum section: electronics / beginners

author: LoveLaika
author_rank: Frequent Contributor
timestamp: June 14, 2022, 08:54:47 pm
content: I worked out equations for an ideal buck-boost converter, but I think I'm not sure if I wrote it correctly. So, I wanted to ask here.In my attached image, I have two equations: one for V_L and one for I_C. Drawing out 'rough' circuits for them yield the two halves, and seeing the relation of the dependent sources, you can replace the set of dependent sources with an equivalent transformer (on paper). I was wondering if I did it correctly though?The equation for V_L yields the circuit on the left using KVL. The equation for I_C yields the circuit on the right using KCL. Using the top node as the node to implement KCL (and assuming that the capacitor current is 0), the current going into the node should equal the current leaving the node. However, the signs are tripping me up. If you look on the set of equations at the top right to describe the right circuit, since I_R is negative, then V would be negative (oops, that resistor should just be V, not V/R. My bad). Given the way the circuit is drawn, did I replace the sources correctly with the transformer's dot notation in the right locations?Also, if I draw out an equivalent Thevenin circuit for the secondary load R, do I have to do anything special with regards to the tranformer's polarity?

author: ledtester
author_rank: Super Contributor
timestamp: June 15, 2022, 01:33:09 pm
content: Quote from: LoveLaika on June 14, 2022, 08:54:47 pmThe two sides of your transformer do not have any reference to a common voltage so I don't think the phasing dots matter.In LTspice, for instance, every part of your circuit needs to have a reference to ground and so you don't have this situation.

author: ledtester
author_rank: Super Contributor
timestamp: June 15, 2022, 08:26:01 pm
content: Quote from: LoveLaika on June 14, 2022, 08:54:47 pmHere's a video on deriving the network equations for an ideal transformer:

author: LoveLaika
author_rank: Frequent Contributor
timestamp: June 20, 2022, 02:11:02 pm
content: Thanks for the reply, as well as the link to the video. Sorry for not being able to reply sooner. I see that I forgot to put down a common voltage, but to be clear, the bottom node on both sides of the circuit could be considered the reference/common voltage linking the two circuits.
Is op amp supply current on datasheet per channel? - Page 1
Forum section: electronics / beginners

author: Bootalito
author_rank: Unknown
timestamp: December 30, 2018, 03:54:08 am
content: I'm searching for an optimized 4 channel op amp to drive a 4 parallel mosfets for an electronic load. I'm able to achieve ~0.02A/uSwith an AD8630 by using a 330R resistor to gate or about 15mA per channel. The AD8630 has an output short circuit current of 50mA, so I'm a bit overspec, but its stable. I need more power!The AD8534 says it has a "250mA Output". Then I realized I didn't actually understand if the datasheet specification for "Output Current Limit", "Output Short Circuit Limit", etc, was for the entire device or per channel. I figured these specs were for the entire device regardless of if its a single or quad channel amp. But I really don't know!I'm using the same mosfets as the Rigol Electronic load, and it has a claimed spec of 5A/uS with 12 Fets. I think it has a 3.3R resistor and when you do the math with the gate charge its in the ball park of 5A/us. How does one deliver 4Amps to a mosfet gate in the linear region in a controlled manner? I mean you can use a gate driver, but that's just for slamming the gate open and shut.

author: Nerull
author_rank: Frequent Contributor
timestamp: December 30, 2018, 04:04:03 am
content: https://www.analog.com/media/en/technical-documentation/data-sheets/ad8531_8532_8534.pdfPage 11 has section on maximum power

author: Bootalito
author_rank: Unknown
timestamp: December 30, 2018, 04:45:16 am
content: ThanksIn an electronic load application the application of power is so brief as to be non-consequential though. Although in that section it says the minimum resistor one should place on the output is 20R. 5V / 20R = 250mA. But what if I'm using a quad package? Does this mean I can put 20R resistors on each output? Meaning that the entire package will be driving 1A of power for about 50us
Is optocoupler only suited for switcing applications??? - Page 1
Forum section: electronics / beginners

author: ajoseph88
author_rank: Contributor
timestamp: September 23, 2015, 03:57:06 pm
content: Can an opto-coupler be used to provide isolation in feedback circuits...eg. say in my case, where the input voltage of 0 to 200V D.C is from the armature of a dc motor, is passed through low pass filter and a voltage divider, and the final output is 0 to 5V D.C, but i did not provide any kind of isolation... what can we use to provide isolation. can we use a opto-coupler, but the output voltage after isolation should vary linearly from 0 to 5V as the input varies from 0 to 5V.Or is buffer-opamp a good choice... What can I use to provide isolation...I searched on the internet and found some DC/DC isolators like "recom r1s 0505", but the problem with that is, the output is a constant 5V, and is useless for feedback applications....

author: Tomorokoshi
author_rank: Super Contributor
timestamp: September 23, 2015, 04:32:51 pm
content: A couple options:1. Analog linear optoisolator:https://www.digikey.com/product-detail/en/HCNR201-500E/516-1773-1-ND/18943172. Use a separate micro at the motor and run communications through a digital optoisolator to the other side.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 23, 2015, 04:37:23 pm
content: An Optokcoupler can also be used in alalog feedback applications. Many switched mode supplys use this to control the voltage.However one should keep im mind that normal optocouplers are not very linear, not temperarure stable and can age. So feedback should only transfer a signal that is not that sensitve. Often that means havening the reference value on the sender side, and integrate the transfered signal. So dirft of the optocoupler will silghtly alter the speed, but not the final value.So direct transfer of the 0-5 VsSignal would require a special linear optocoupler or a different isolation.

author: ajoseph88
author_rank: Contributor
timestamp: September 23, 2015, 05:47:15 pm
content: How about buffer or unity gain op-amp configuration... They call it isolation amplifier...I have the op-amp ready at my place, so is it a good option or High linear analog optoisolator HCNR201-500E as said by one of the gentleman... Which one should I go for...

author: macboy
author_rank: Super Contributor
timestamp: September 23, 2015, 09:11:39 pm
content: Quote from: ajoseph88 on September 23, 2015, 05:47:15 pmBoth at the same time actually. Download, read, and understand the data sheet for the analog optocoupler. Generally they have two outputs; one goes inside the feedback loop of an op-amp on the non-isolated side, and the other goes on the isolated side. This is necessary to provide a linear transfer function.
is PhoneFix diyfixtool.com legit to buy stuff? - Page 1
Forum section: electronics / beginners

author: river
author_rank: Contributor
timestamp: November 05, 2022, 04:03:29 am
content: I saw a youtube video for the Aixun, and the poster (VCC Board repairs) said he bought everything Aixun from PhoneFix (diyfixtool.com).I have never heard of diyfixtool.com before but all the prices even with the $30 shipping fee is still less than Aliexpress for Aixun and other soldering tools. they also have oem JBC handles.I'm worried since I have not bought or heard about them before. Does anyone know anything about them or safety?Video review is hereand he links in the comments the website to buy it. They sell the Aixun T3A I am interested in is $30 less on this place than on AliExpress (even after large shipping cost added).I'm not sure I posted this in the right place.thanks

author: river
author_rank: Contributor
timestamp: November 05, 2022, 08:56:43 pm
content: If there is a better place I can post this question please let me know . thanks

author: Haenk
author_rank: Super Contributor
timestamp: November 05, 2022, 10:32:06 pm
content: This seems like a legit site, lots and lots of specialized tools and a large number of blog/media posts (also specialized and not copied from other sites), lots of contact information and payment possible via PayPal.For a quick scam, that would be just too much stuff going on.But that's just my impression.

author: river
author_rank: Contributor
timestamp: November 08, 2022, 01:14:01 am
content: thanks

author: razecus
author_rank: Newbie
timestamp: January 26, 2024, 10:29:05 am
content: Hello people,I had an order on this site, i got myself a webcam with a c-mount, but my experience is not a happy one.Other than the typical specs scam i don't know what to say you shall expect.specs war like this:5.0MP 4K Webcam Specification:Image Sensor: CMOSHigh Definition:5 Megapixelsi got2 MegapixelsSensor Type:IMX317- this is a pipe dream - in the box was an AX USB2.0 (vendor ARC International?) which can work at max 1920x1080 30fps ishResolution:30FPS (3840*2160), 30FPS (1920*1080)Output Format: YUY2/MJPGMaximum Resolution:3840x2160only30FPS (1920*1080)
Is possible to make a clock from a 555 timer? - Page 1
Forum section: electronics / beginners

author: LinkZ
author_rank: Contributor
timestamp: May 19, 2015, 07:16:14 pm
content: I've found this site (http://www.engineersgarage.com/contribution/digital-clock-without-microcontroller) which claims that is possible to make a led clock from a 555 timer and few other parts.here is the schematics:url immagineCan this circuit work?If yes, in the description it says that few basic and/or gates are required. Which should I use?

author: Zero999
author_rank: Super Contributor
timestamp: May 19, 2015, 07:21:08 pm
content: Not really. A clock made with an RC oscillator won't keep time and will drift all over the place.Use a 32768Hz crystal and a divide by 15 counter to get a 1 Hz time base.

author: German_EE
author_rank: Super Contributor
timestamp: May 19, 2015, 07:24:34 pm
content: The 555 just supplies one pulse a minute to drive the first counter. All of the chip information is there apart from the AND and the OR gates, so have a quick look in a 74HC series catalog and see if you can find themANd yes, this will drift like crazy.

author: smjcuk
author_rank: Frequent Contributor
timestamp: May 19, 2015, 07:30:37 pm
content: Built something similar to that in 1991. No idea what happened to it to be honest. Probably nicked the bits for something else.

author: Simon
author_rank: Unknown
timestamp: May 19, 2015, 07:41:40 pm
content: Ypou can make a closk oscillator with unbuffered cmos gates and a 32.768 KHz crystal, I did this for a friend to make a 30 second ticker but used a microcontroller and fed the 32.768KHz in as an interrupt to keep time
Is "read access speed" in datasheet matter for flash ic?  - Page 1
Forum section: electronics / beginners

author: debi
author_rank: Contributor
timestamp: April 23, 2023, 07:57:59 am
content: Hi guys,im trying to source a flash SST39vf040 90-nh-4C (plcc format)... unfortunatly i only can find SST39vf040 70-nh-4c. Looking at the datasheet there is only a difference between 90ns and 70ns read access speed. In case i put a 70-nh-4c, what is going to happen ? Sorry for this noob question.https://html.alldatasheet.com/html-pdf/46905/SST/39VF040/1015/20/39VF040.htmlcheers !

author: BadeBhaiya
author_rank: Regular Contributor
timestamp: April 23, 2023, 08:30:50 am
content: You should be able to use it without a problemThe access time difference is quite insignificant.

author: debi
author_rank: Contributor
timestamp: April 23, 2023, 10:03:43 am
content: Quote from: BadeBhaiya on April 23, 2023, 08:30:50 amHello,thanks for your helpdo you why they made different acces speed ic with so little difference if it's not that important ?cheers

author: wraper
author_rank: Unknown
timestamp: April 23, 2023, 10:16:24 am
content: There is no issue using IC with lower access time. Access time is rated for worst case only, therefore it's easily possible that some 90ns IC actually can be faster than 70ns IC.QuoteIt is important if you need to operate them fast. It's not like they have a different silicon die. Manufacturer bins them in production and can sell faster ICs for more. If they produce more of faster ICs than market demands, manufacturers often sell faster ICs as lower grade.
Is Siglent sds2104x oscilloscope "Upgradble"? - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: April 09, 2018, 06:20:54 am
content: Thinking about getting a Siglent sds2104x oscilloscope, because it is about how much I can afford but less then what I think that I may need later on. So the big question, is there a free way to "upgrade" it to the full 300 Mhz?

author: tautech
author_rank: Super Contributor
timestamp: April 09, 2018, 07:28:50 am
content: Quote from: FriedMule on April 09, 2018, 06:20:54 amNo not at this time.There's a promo on SDS2kX models ATM so the 200 MHz version is the same or better price as the 100 MHz model was before the promo.See here:https://store.siglentamerica.com/product-category/digital-oscilloscope/sds2000x-series/If you click the model you're interested in there's a further promo available for the options package.

author: FriedMule
author_rank: Frequent Contributor
timestamp: April 09, 2018, 09:52:53 am
content: unfortunately I do live in Denmark but Siglent.eu does properly also have sale.The price is just to high for my taste so again, if it was possible to upgrade:-)

author: tautech
author_rank: Super Contributor
timestamp: April 09, 2018, 11:42:19 am
content: Quote from: FriedMule on April 09, 2018, 09:52:53 amThe link I provided came from this page:https://www.siglenteu.com/digital-oscilloscopes/sds2000x/BTW, Siglent.eu is not Siglent in Hamburg.
Is Single to Differential Conversion Really Needed? - Page 1
Forum section: electronics / beginners

author: gigavolt
author_rank: Contributor
timestamp: April 06, 2023, 02:19:00 am
content: I have a differential ADC lying around, but want to use it to digitize a single-ended signal. According to its reference design, TI recommends sticking a differential output op amp in front and using that to drive the ADC. My question is if this is really necessary or if I can just connect in_negative to ground and the (always positive) signal to in_positive?Also, I did hear that ADC inputs can be unfriendly. Maybe that's a good reason to use the driver? However, the input signal is itself coming from an op amp.The diagram is on page 33 of the following PDF.https://www.ti.com/lit/ds/symlink/ads8867.pdfedit: removed garbage from the link

author: jwet
author_rank: Frequent Contributor
timestamp: April 06, 2023, 04:06:17 am
content: In most cases the common mode voltage of diff input ADC's is limited, but the particular device that you've chosen has an unusual R-R common mode input range. You should be able to do what you want. A few considerations- you're giving up 6 db or 1 bit of resolution right off the bat since your input is unipolar- 15 bits is still pretty good. The input is a 55 pF cap behind an analog switch- that's a rough load. Look at the DS around for recommendations- it looks like something like 100 ohms on the op-amp output and then a 1000 pF cap to ground, the slug of current for the input will come from that cap- the sereis R will keep your amp from oscillating. It sounds like you're just experimenting- it will certainly work if you take a little care with the single ended drive to keep your driver happy.

author: gigavolt
author_rank: Contributor
timestamp: April 06, 2023, 04:08:14 pm
content: Thanks! That's good to know.I'm adding an antialiasing filter right before the ADC too, so hopefully that cap can help out with the filling up the ADC's input.
Is SMD capacitor that is so small, 1-2 x 1-3 mm non polar - Page 1
Forum section: electronics / beginners

author: abdulbadii
author_rank: Frequent Contributor
timestamp: February 04, 2023, 12:20:41 am
content: Is SMD capacitor that is so small, 1-2 x 1-3 x 1 mm always non polar ?How many Farad max do such kind of capacitors have?

author: inse
author_rank: Super Contributor
timestamp: February 04, 2023, 08:36:35 am
content: If there is no marking on it, it is not polarized.The capacitance can be anything from pF to uF

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: February 04, 2023, 11:14:08 am
content: A good picture would be helpful in identifing the type.All polarized capacitors are marked in some way.Jeff

author: jpanhalt
author_rank: Super Contributor
timestamp: February 04, 2023, 11:21:02 am
content: Quote from: abdulbadii on February 04, 2023, 12:20:41 amNo.Check any decent supply house. Why do you inquire?
Is Sodium Persulphate going to attack heatshrink? - Page 1
Forum section: electronics / beginners

author: Noize
author_rank: Regular Contributor
timestamp: October 08, 2012, 03:15:31 pm
content: I am currently building an etching tank set up with 25 watt aquarium heater, and air pump. A thermistor comparator circuit will control the heater.I will be using sodium persulphate at 45c for the etchant.I am going to waterproof the thermistor with heatshrink, is that suitable(is the sodium persulphate going to attack it.) or is there better stuff than heatshrink?Haven't got any heatshrink to test unfortunately, going to get some.Just thought about putting the thermistor in a test tube full of johnsons baby oil(mineral oil) and immersing that, but it probably has too slow response?By the way sodium persulphate starts to decompose at 50c

author: SeanB
author_rank: Super Contributor
timestamp: October 08, 2012, 03:51:43 pm
content: Use a heatshrink with an internal adhesive layer, which will melt to form a waterproof seal around your sensor.

author: Noize
author_rank: Regular Contributor
timestamp: October 08, 2012, 04:15:21 pm
content: Quote from: SeanB on October 08, 2012, 03:51:43 pmNice I will get some of that thanks

author: Alana
author_rank: Frequent Contributor
timestamp: October 09, 2012, 07:33:08 am
content: In case of lack of the shelf solution the usual replacement is pot sensor in hot glue, then shrinkwrap it. Tested, had no problems up to now.
Is some ESR normal ? - Page 1
Forum section: electronics / beginners

author: Hextejas
author_rank: Frequent Contributor
timestamp: September 25, 2018, 11:43:26 am
content: Just for grins I measured the capacitance and ESR of an expensive new cap.It is a Nichikon, 100uf, 63v and the ESR is 0.48 ohms.I guess that I expected it to be 0.00.Was that unrealistic and is it normal that caps will have some ESR ?I tried to read the datasheets but had no luck.Thanks

author: helius
author_rank: Super Contributor
timestamp: September 25, 2018, 11:46:56 am
content: Expecting 0Ω ESR from any electrolytic cap is completely unrealistic. ESR from a healthy electrolytic cap will be on the order of 1Ω.As I posted in another thread recently, you can compute the specified ESR from the Dissipation Factor using \$ ESR = {DF \over 2 \pi f C} \$There is also a handy chart on the back of those cheap ESR meters that guides you to the value to expect.
Is switching a hifi receiver push button using an optoisolator OK? - Page 1
Forum section: electronics / beginners

author: slekvak
author_rank: Newbie
timestamp: September 26, 2016, 09:11:59 pm
content: Hi!My receiver has a speaker select (zones) toggle on the front of the chassis, with a simple push button behind it. As far as I can tell from the service manual, the button is switched to chassis ground and connected to a input on a microcontroller. I am planning on switching it with a Raspberry Pi or an Arduino.Would it be safe to use a optoisolator for this, or do I need a relay? I have soldered two wires to the push button, shorting them seems to work fine, and was hoping I could use a "4N35 FSC Optocouplers Phototransistor 30V DIP6" I have available...Snippets from service manual:I hope someone is able to give me some advice (and/or comfort)

author: Paul Moir
author_rank: Frequent Contributor
timestamp: September 26, 2016, 09:20:16 pm
content: Sure. Richard Crowley turned me on to using optofets such as the H11F1M series because then you don't even need to know polarity. But you have the parts and you have the schematic so that's no problem.It's possible (but almost definitely not true) that they're putting some current through the switch which would mean you'd have to drive the LED pretty hard to "press the button". You could simply measure the current going through the switch using a multimeter on a mA range. The 4N35 has a guaranteed minimum current transfer ratio of 1, which means if you put 10mA through the LED it will allow 10mA through the phototransistor.

author: george.b
author_rank: Frequent Contributor
timestamp: September 27, 2016, 06:17:58 am
content: It should work. I mean, it's just a logic pin, I doubt it'll drain much current through the optocoupler.
Is SysML Used in EE? - Page 1
Forum section: electronics / beginners

author: eev_carl
author_rank: Regular Contributor
timestamp: March 14, 2020, 06:43:20 pm
content: Hi,Does anyone in EE use SysML for wiring diagrams? I'm talking about a diagram like this.-Carl

author: Zero999
author_rank: Super Contributor
timestamp: March 15, 2020, 10:28:40 pm
content: No, I've never heard of it.

author: filssavi
author_rank: Frequent Contributor
timestamp: March 15, 2020, 11:18:43 pm
content: I have never seen it eitherIn the automotive world there are a couple of standard wiring diagram types for one overall connections and one for cable harnesses (what pin of what connector goes where) but they all are very close to regular schematics in overall logic and they are usually done with whatever CAD package the mechanical part is made in

author: Just_another_Dave
author_rank: Regular Contributor
timestamp: July 16, 2021, 02:31:13 pm
content: I used once Sysml when designing a power supply architecture as it was part of a bigger project designed by systems engineers. In my experience, it is quite uncommon in EE, but it is sometimes used when the circuit is part of a complex system that contains mechanical and electrical components, as well as programmable devices (for example a robot).If the project just involves electronic circuits, schematics and block diagrams are more widely used as they are easier to use. Additionally, the person in charge of soldering the pcb will be expecting an schematic and other representations might make his job more difficult (for example a circuit described in python)
is tektronix gds 220 worth it for 140$ - Page 1
Forum section: electronics / beginners

author: OwaisAhmed
author_rank: Contributor
timestamp: May 09, 2022, 11:37:47 pm
content: this would be my first ever oscilloscope. today i went to the market and saw this oscilloscope for 140$ with probes included. need scope for repairing power supply checking laptop motherborad and pc motherboard 50 to 75 mhz signal. before that ii was about to buy hantek 2c10 but ii couldn't afford it. do anybody have an experience with this scope and does this model has some problems. and what about interface and display quality. and does oscilloscope hang or freeze!!!

author: EEVblog
author_rank: Unknown
timestamp: May 10, 2022, 01:52:42 am
content: You mean TDS220It's an ancient scope which still has a community of fans.Still very useful for $140. If in good condition you could probably resell on ebay for more than that.Small memory, poor and slugish display, but remember, at one point in time this was the most popular digital scope in the world. It does not hang or freeze.

author: WattsThat
author_rank: Frequent Contributor
timestamp: May 10, 2022, 02:43:10 am
content: And it boots up in seconds…But it’s a first generation digital monochrome LCD scope. If complete with all knobs and probes, especially if they’re not $5 eBay specials, $140 is probably fair market value in most places. It’s feature-less. Very basic. No screen capture.If you’re thinking about probing around on the primary/mains side of a pc or switching power supply, think again. That’s a no go with standard probes, you need a differential probe for that which will cost more than the scope. Be sure to watch Dave’s video on how to not blow up your scope:https://youtube.com/watch?v=xaELqAo4kkQ