hybridfree/eevblog-posts huggingface dataset:
hot air pencil not working - Page 1
Forum section: electronics / beginners

author: zze110
author_rank: Contributor
timestamp: December 04, 2014, 02:18:57 am
content: Hello,I am trying to remove a surface mount 10/100 ethernet chip from a pcb and replace it. I purchased one of the cheap ebay hot air pencils thinking the chip would fly right off the board.However, I cannot even make the solder melt. I can melt solder easily on the roll but nothing on the PCB. I tried adding some solder to the chip leads and it applies immediately. Once there it hardens and I am unable to melt it again!I am thinking the board is sucking out all the heat I apply before the solder gets hot enough. How can I keep this from happening and remove the part? The chip is a 48-pin lqfp package.Thank you.

author: tautech
author_rank: Super Contributor
timestamp: December 04, 2014, 02:31:11 am
content: Welcome to the forum.You will need to add additional heat on the PCB.Either a hot air gun or pre-heat in the oven and work quickly.Some carefully cut the package leads and then de-solder each lead.Be careful not to rip the pads up.

author: divelectservices
author_rank: Contributor
timestamp: December 04, 2014, 02:31:59 am
content: You need a preheater under the board.

author: zze110
author_rank: Contributor
timestamp: December 04, 2014, 04:52:40 am
content: Thank you, I will try to get one.The board I am working with I believe was wave soldered. I read that they use glue to adhere the chips to the board? Would this cause an additional problem if true?Thanks again!

author: aargee
author_rank: Frequent Contributor
timestamp: December 04, 2014, 06:47:00 am
content: Most likely unleaded solder. A real PITA as it doesn't often play well with leaded and has a higher melting point.

author: Howardlong
author_rank: Super Contributor
timestamp: December 04, 2014, 07:38:05 am
content: Be aware that if it's on a multilayer stack, melting solder is quite a bit harder than on a one or two layer board as the ground plane layer has a lot of thermal mass.If the chip in question is a QFN oe other device that has a ground pad under the chip this makes the job harder too.Is it a hot air pencil, or a hot air desoldering gun? A pencil will be useless for a chip bigger than about 4mm^2. A pencil looks like a normal sized soldering iron but with a small bore for the hot air, perhaps a couple of mm diameter bore and a shaft under about 1cm diameter. A hot air desildering gun has a shaft diameter of 2 or 3cm, and a bore in step with that, and should be able to completely cover the chip with heat without waving it around given the appropriate funnel tip (or occasionally no funnel tip at all for the bigger devices).Make sure you have the air turned up enough, and there's enough temperature. Mine is at 320C. For multilayer boards with embedded ground planes it has to be within a couple of millimeters of the chip for about twenty seconds or so to shift it. You can see the solder melt on each pin under the microscope, and I prod the chip a little evey now and then with the tweezers until the ground pad melts too and the chip moves, then lift it off.
Hot-air rework near a thermally sensitive component? - Page 1
Forum section: electronics / beginners

author: bitwelder
author_rank: Super Contributor
timestamp: July 28, 2016, 12:21:35 pm
content: Let's say that I want to rework a SMD chip using the hot-air gun, but few cm away on the PCB there is some component that is thermally sensitive, e.g. an electrolytic.What's the correct way to proceed in order to avoid damaging that component?I've seen in some rework videos that a barrier of alu foil is used, sometimes held in place with kapton tape. Is that all that is possible, or there are smarter ways?

author: StuUK
author_rank: Frequent Contributor
timestamp: July 28, 2016, 12:56:22 pm
content: Foil and Kapton would be my first choice

author: MosherIV
author_rank: Super Contributor
timestamp: July 28, 2016, 01:14:10 pm
content: QuoteElectrolytics are not that thermally sensitive.However, in many places where I have worked, they use a hot plate or pre-heater to heat the whole board up to just below the melting point of solder.Then they use the heat gun to melt/reflow just the component being reworked.This minimises the thermal stress of the components around it.

author: eKretz
author_rank: Frequent Contributor
timestamp: July 29, 2016, 04:30:36 am
content: I often use foil placed around the component being worked on and just wrap/form it so it doesn't get blown off. I also use the oven preheat method, it works well too. Another bonus of the foil is that it keeps any tiny SMD parts nearby (i.e. BJTs) from blowing away should their solder happen to melt also.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 29, 2016, 05:20:20 am
content: Quote from: bitwelder on July 28, 2016, 12:21:35 pmuse thermo insulator shielding instead of alu foil the thermal not insulator.

author: jitter
author_rank: Frequent Contributor
timestamp: July 29, 2016, 11:13:49 am
content: Quote from: MosherIV on July 28, 2016, 01:14:10 pmWe normally use a pre heater only on thermally "difficult" parts or boards.Having access to a pro tool like this......means I can use the metal bucket like shields in the foreground to put around the component to be reworked. If that doesn't fit because of nearby components in the way, then kapton tape is the "plan B"...If you're handy with alu foil, maybe you can fold something into shape. It may not be a thermal insulator, it will keep the hot air away from sensitive components.
hot air soldering station for beginners - Page 1
Forum section: electronics / beginners

author: Boschi
author_rank: Regular Contributor
timestamp: December 27, 2017, 12:42:33 pm
content: first of all i briefly searched on google "hot air soldering station eevblog" but nothing recent has came up, so im asking againanyway, as a student that is starting to mount some pretty dense PCB i feel the need of a hot air gun.do you have any suggestion? i already have a fx888, so i dont need any soldering iron / hot air station bundle, i just want something cheap enough and i dont need much power (currently im working on 1" * 3" PCB). what do you recommend?if possible it should have temperature control and airflow control, but i have no experience in the field, so feel free to suggest anything that you find useful.thanks!

author: Belrmar
author_rank: Regular Contributor
timestamp: December 27, 2017, 03:43:28 pm
content: i dont realy know much about hot air soldering stations but Louis Rossmann has some pretty interesting stuff about them on his youtube channel

author: agehall
author_rank: Frequent Contributor
timestamp: December 27, 2017, 04:03:01 pm
content: There are tons of threads on the subject in the Other Equipment & Tools section.To save you time - just get a Quick DW861.

author: Boschi
author_rank: Regular Contributor
timestamp: December 27, 2017, 04:46:48 pm
content: Quote from: Belrmar on December 27, 2017, 03:43:28 pmi gave him a try and i think his choices are a bit over my budget, i dont do any professional work, so i dont need any fancy stuff.Quote from: agehall on December 27, 2017, 04:03:01 pmsorry i missed that section.about the DW861 its too pricy. the cheaper the better for me.looks like the Atten 858D is still the best option in this price range.

author: xraj
author_rank: Contributor
timestamp: December 30, 2017, 05:49:33 am
content: I have an older version of this which has been working for me.https://www.circuitspecialists.com/csi825a.htmlIt has the air pump in the main body which keeps the gun/wand less bulky. Spare parts are readily available from the vendor. I believe mine even came with a spare heating element (which I haven't needed yet).

author: KL27x
author_rank: Super Contributor
timestamp: December 30, 2017, 02:17:12 pm
content: 858D is an incredible unit for the functionality, size, ergos, and price. I binned a larger multi-function (and more expensive) unit for the 858D. I wouldn't dream of "upgrading." I'd buy a new one every year, if that's how long it lasted. Mine is going on for at least 2 or 3, now, with pretty heavy use.
Hot Air Soldering - Page 1
Forum section: electronics / beginners

author: FlyMario
author_rank: Contributor
timestamp: January 07, 2018, 01:24:23 am
content: So many years I have soldered with normal soldering irons. Lately I have been thinking of getting an Hot Air soldering station.However I wanted to ask a question. Do people solder through hole with Hot Air Stations or strictly with soldering irons?It kind of seems like it would make a cleaner job with the Hot Air but figured you guys might have a better idea.Thanks,FlyMario

author: FlyMario
author_rank: Contributor
timestamp: January 07, 2018, 01:36:01 am
content: Thank you! You make a lot of sense here. Don't need to break what works anyways.FlyMario

author: helius
author_rank: Super Contributor
timestamp: January 07, 2018, 01:46:23 am
content: Hot-air (or using an inert gas like nitrogen) has advantages for SMD rework, but it conducts heat into plated thru holes more slowly than contact soldering. One of the few hot-air systems designed for thru-hole assemblies is theZephyrtronics ZT-6; it uses masks to prevent overheating surrounding areas, but this is for very dense backplane connectors etc and not for general thu-hole soldering.

author: cdev
author_rank: Super Contributor
timestamp: January 07, 2018, 02:33:14 am
content: Blueskull, thank you for all your soldering tips.Quote from: blueskull on January 07, 2018, 01:28:56 am

author: Kilo Tango
author_rank: Regular Contributor
timestamp: January 07, 2018, 03:03:27 pm
content: Not for thro hole soldering but Hot Air is pretty good if you want to desolder a DIP. You either go round all the holes with a solder sucker and possible solder wick, and its still touch and go if you damage the plated thro holes when you pull the IC out, but if you use a decent hot air system you can heat up all the pins at once and just pull it straight out.Ken

author: cdev
author_rank: Super Contributor
timestamp: January 07, 2018, 04:18:16 pm
content: I recently got a digital hot plate that's intended for use with soldering - it has a big slab which you can heat up to hot enough so only a tiny bit more heat melts the solder. Using it you can make the soldering and desoldering process a lot more controllable because you don't have to overheat it because its already almost hot enough to melt.You have to be careful not to touch it, obviously. I've been using a metal stick vise to hold the work. (many of them come with one built in, mine didn't)So, I often use two at the same time, preheat and hot air for removal (and sometimes to solder, but mostly desoldering). Preheating keeps the work hotter so I can use the smaller nozzles on the hot air, using tweezers to lift up and move the parts. I have quite good small tweezers but need some better quality long tweezers.Also, preheat plus soldering iron to solder.A digital hot plate also works well for reflowing - You can see exactly when the solder melts.
Hot Air Station "Classes": Atten ST-862D vs Quick 8XX - Page 1
Forum section: electronics / beginners

author: untribium
author_rank: Newbie
timestamp: November 06, 2023, 01:07:00 pm
content: Hi all,I've done a bunch of hand soldering using my trusty Seeed mini iron, but am now looking to get into slightly more serious stuff. Specifically, custom designed PCBs for various hobby projects, similar in complexity to what Joe Barnard is doing for BPS.space, for those of you who know him (https://youtu.be/RjcQDPvVHno). In a nutshell, small-ish PCBs (max 100x100mm, i.e. 4x4") with a microcontroller, some sensors, etc. At the moment, I don't expect to get into major repair work for larger PCBs, so that's not a priority but I suppose it wouldn't hurt to have the capability, should the need arise...I'd like to get a station of decent quality but obviously it doesn't need to be pro level. So the question is whether I should go for an Atten ST-862D/Quick 861DW (1000W/120L) or something smaller like e.g. a Quick 859D+ (600W/50L). Price isn't a huge concern, I'll happily invest an additional $100 if it's worth it. Desk space actually matters more, but same thing, happy to move stuff around if it makes sense to go for a bigger machine.To refine/rephrase the question:What are the tasks I can get done with the ST-862D that I'd struggle with using a smaller machine?Thanks!PS: Apologies if this is a repeat question, I looked around but kind of hard to know what to search for.
hot air station how to test ? - Page 1
Forum section: electronics / beginners

author: angellonewolf
author_rank: Contributor
timestamp: February 05, 2013, 09:43:21 am
content: i have just got a hot air station but i cant even burn a piece of cardboard let alone remove a componenti assume its knackardits producing heat but not i think very much i set it on 340 air speed 4 i held it over a resister for 2 to 3 mins moving it around not any movement at all i held it directly over it for 2 mins did not even burn or heat up so i put the heat up to 400 and the same air speed and put it over a cardboard box held it there for 2mins not even a burn markany ideasthanks angel

author: jaqie
author_rank: Regular Contributor
timestamp: February 05, 2013, 09:55:00 am
content: got an oven thermometer made of metal to hold an inch away from the nozzle?

author: angellonewolf
author_rank: Contributor
timestamp: February 05, 2013, 10:32:36 am
content: good thinking may need to think about some thing like thisany more ideas so i can test it

author: Psi
author_rank: Super Contributor
timestamp: February 05, 2013, 12:51:50 pm
content: To test the heat, hold a bit of solder at the nozzle. It should melt within 2 seconds.But yeah, it sounds like there is something wrong with the unit.I have to be quite careful where i point mine or i end up putting burn marks onto my wooden desk

author: angellonewolf
author_rank: Contributor
timestamp: February 05, 2013, 01:11:31 pm
content: got one of the temp units it shows 160c after 2 mins even if the unit said temp is 340 i wonder if the heating element is gone ? or if the element is gone does it not work at allwill try the solder in a minthanks for the help guysangel

author: angellonewolf
author_rank: Contributor
timestamp: February 05, 2013, 02:20:21 pm
content: it did melt a .65 mm leaded solder but just i turned up the heat untill 480 and tryed it on some very small components its worked but took ages 40-60 sec and i did not even move the tool more than 2 -5 mm from the componentthanks for the help

author: Circuitous
author_rank: Unknown
timestamp: February 05, 2013, 02:38:37 pm
content: It almost sounds like the setting is in Fahrenheit. When set at 340 F, you should get about 170 C. And having it at 480 F should melt solder, but maybe a bit slowly, particularly if it's running a few degrees cooler than the set temp.

author: angellonewolf
author_rank: Contributor
timestamp: February 05, 2013, 10:45:47 pm
content: cheaked the details on line and up to 480c

author: andreiu21
author_rank: Newbie
timestamp: March 11, 2013, 05:24:18 pm
content: Use your multimeters K-type temperature probe. (If you have one)

author: ptricks
author_rank: Frequent Contributor
timestamp: March 11, 2013, 08:23:02 pm
content: What size is the nozzle attachment ? More air can be a bad thing with some stations because the heating elements cannot keep the target temp with a lot of air flow.

author: codeboy2k
author_rank: Super Contributor
timestamp: March 11, 2013, 09:33:01 pm
content: Here's a hot air test using 3 thermocouples for temperature verification.The test is for a Aoyue 968 , and shows it is way off the displayed temperature
Hot bar machine power supply - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: September 25, 2015, 05:05:41 am
content: Does anyone have any knowledge what kind of power supply must be used in hot bar machines?I can find details about power supplies of spot welders but not about power supply hot bar machines.

author: tron9000
author_rank: Frequent Contributor
timestamp: September 25, 2015, 07:58:57 am
content: judging from this video:I'd say it was constant current based, due to the exposed contacts.
HOT side adjustable POT for phase angle controller - Page 1
Forum section: electronics / beginners

author: AlessandroAU
author_rank: Regular Contributor
timestamp: March 30, 2015, 04:46:35 am
content: When using integrated Phase Angle Controller chips they are often adjusted by using a POT connected to the hot side of the mains supply. (See attached)If I wanted to replace the pot with a micro, what is the best approach to provide isolation?

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 30, 2015, 06:11:05 am
content: I don't know of any good solution to a properly-isolated solution for a variable resistance. To be sure, there are micro-controlled potentiometers. But none of them have the kind of isolation you would need when controlling a mains-connected power circuit like that.The typical way of doing phase-angle control from a microcontroller is to have the microcontroller monitor the zero crossing and then simply drive an opto-isolator feeding the SCR/Triac (or a random-triggering solid-state relay, SSR).For example, here is an Atmel Application Note showing how to monitor the zero-crossing of the mains power....http://www.atmel.com/images/doc2508.pdf
Hot-Swapping killing IC's - Page 1
Forum section: electronics / beginners

author: Apn15
author_rank: Contributor
timestamp: January 20, 2022, 04:20:51 pm
content: I have a project where I am using a TI TPS7B6933DBVR to power an EEPROM and a NAND gate that is used for an external IC BOOT circuit.This regulator is power by a LiFePO4 battery at 24V, but whenever I remove and re-apply power, it appears that the regulator and other IC's have shorted to ground.I have found a few articles online about this issue, but none seem to have any solutions. Is there anything I could add to the circuit to help or prevent this from happening.See below for shots of the circuits.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 20, 2022, 04:55:40 pm
content: With the regulator specified up to 45V transient, this is not necessarily the right answer, but anyway:The large 10uF MLCC capacitor causing inrush voltage peaking with inductive supply wiring. This can easily go up to twice the input voltage, and sometimes even beyond.Try the trivial fix: solder any 100uF or so electrolytic capacitor (which, by definition, always have significant ESR) in parallel with the 10uF MLCC.Seehttps://www.analog.com/media/en/technical-documentation/application-notes/an88f.pdffor more information.

author: Apn15
author_rank: Contributor
timestamp: January 20, 2022, 07:08:40 pm
content: Thanks for the suggestion and the Article.I am going to order some different capacitors and may try the series resistor circuit that was in the article.

author: Apn15
author_rank: Contributor
timestamp: August 22, 2022, 04:14:13 pm
content: I am returning to this project and have tried several solutions to this problem with limited results.The article previously posted suggested a 30V TVS, while it did limit the voltage, the spike was still around 35-38V in practice which is still too high.I have seen several articles for calculating snubber circuits, but they are all for buck or fly-back converters.The oscillation frequency of the transient is 82.64kHz. Is there any way to calculate the snubber circuit I need?

author: Siwastaja
author_rank: Super Contributor
timestamp: August 22, 2022, 04:49:38 pm
content: Did you try the electrolytic capacitor? Anything from the junk box, really, as long as C is significantly larger than the 10uF. Which is why I said at least 100uF.

author: PeteH
author_rank: Unknown
timestamp: August 22, 2022, 05:50:25 pm
content: Why would you not just add a series ~10 to 100 ohm resistor before any capacitance. You don't really care about the voltage drop as the supply is linear anyway. Feel free to add a bunch of series resistance to dampen out the inrush event, limit the peak current to less than 1-2A during hot-swap...Will also help spread the heat out from the LDO.

author: Apn15
author_rank: Contributor
timestamp: August 22, 2022, 05:59:29 pm
content: I did try an 100uF electrolytic capacitor and it did fix my problem. Its a little larger of a solution than I wanted.

author: PeteH
author_rank: Unknown
timestamp: August 22, 2022, 06:00:28 pm
content: Series resistance would result in the smallest solution size.
hot wire powering options - Page 1
Forum section: electronics / beginners

author: cosminnci
author_rank: Regular Contributor
timestamp: October 27, 2013, 02:57:39 pm
content: I have a piece of kanthal 2,5x0,40 mm and about 4mm longI need it to make a groove in depron, I tried with 24v 3A transformer it gets very hot.the element has about 0.1ohm resistance according to ohm`s law would need very high current.I have a old soldering iron the one with copper nose, but with the leads I used it does not heat up enough, maybe the soldering iron is not powerful enough or the wires I use are improper, I need to have it with wires to move it across the depron.what options would I have to heat this element?

author: madires
author_rank: Super Contributor
timestamp: October 27, 2013, 03:55:08 pm
content: 1. determine the temperature required to cut depron2. calculate the current needed to heat up the kanthal to the required temperature and add some margin (check the kanthal specs for the temperature coefficient)3. get a matching PSU and add a simple PWM driver (MOSFET) for adjusting the temperature

author: SeanB
author_rank: Super Contributor
timestamp: October 27, 2013, 07:31:24 pm
content: Get a mains dimmer rated for about 600VA or more of inductive load and put in series with the transformer primary. Turn up power from zero till it cuts correctly and do your cutting. Note the dimmer and transformer will get hot doing this, but provided your duty cycle is a max of 2 minutes on per quarter hour it will work well enough.

author: cosminnci
author_rank: Regular Contributor
timestamp: October 28, 2013, 06:23:28 pm
content: I cut and rounded an old soldering iron tip, and it does the job too.the dimmer method I`ve seen it applied, I have to try it.thank you.
Hours Meter fuse  - Page 1
Forum section: electronics / beginners

author: jonovid
author_rank: Super Contributor
timestamp: December 25, 2019, 09:57:57 am
content: odd fuse type Hours Meter? how does it workin 30 yrs of electronics I have never seen one like this.stop the video here- 7:56Retrotech_ Recordable 'Laserdisc' 22:20

author: StillTrying
author_rank: Super Contributor
timestamp: December 25, 2019, 10:43:27 am
content: I've seen a few over the years, at least until recently you could still buy them.
How a classic diode ring mixer works - Page 1
Forum section: electronics / beginners

author: w2aew
author_rank: Super Contributor
timestamp: August 14, 2014, 12:01:27 am
content: My latest video describes how a classic, double-balanced, diode-ring mixer operates. The basic theory is presented, along with a circuit description and measurements on the bench.

author: bobcat
author_rank: Regular Contributor
timestamp: August 14, 2014, 03:00:43 pm
content: Nice simple explanation of the basic function. Thanks---

author: retrolefty
author_rank: Super Contributor
timestamp: August 14, 2014, 06:27:36 pm
content: Can't underestimate your statement about impedance matching requirements (on all three ports to some degree) to reach best rated performance of such passive mixers.

author: Dongulus
author_rank: Regular Contributor
timestamp: August 14, 2014, 06:59:11 pm
content: ThanksI've always been completely mystified whenever I've looked a mixer circuit, now I'm not.

author: Odysseus
author_rank: Regular Contributor
timestamp: August 18, 2014, 06:23:57 am
content: Great video, just like the rest, as I've discovered! Seriously, watching your channel was all I did this weekend.I had seen the diode ring mixer schematic and the use of diodes as switches before, but now it really clicks for me.I'm curious about the feed-through / isolation characteristics of the diode ring mixer. Seems to me that mismatch in forward voltage of the diodes would manifest itself as increased feed-through of the LO. I've also seen schematics where the center tapped port is used as an input. I wonder what advantages/disadvantages that has in a practical circuit.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 18, 2014, 06:38:02 am
content: The ports are all symmetrical, but if it's transformer coupled, you obviously can't get DC out the two transformers, but you can between the CTs. For BFO type SSB detection, you'd want the BFO on one transformer, IF on the other, and audio comes from the center taps.Tim

author: idpromnut
author_rank: Unknown
timestamp: December 12, 2014, 04:10:33 pm
content: Excellent video, as always!One question that popped up for me was how you choose the number of windings for the transformers? Is there some extra material you can link that helps explain that part? I can understand that if I wanted to adjust this mixer design for a different frequency range, that I would need to adjust the diodes used, but how would I go about figuring out what I need to change in terms of the transformers?Thanks again!

author: w2aew
author_rank: Super Contributor
timestamp: December 12, 2014, 05:16:48 pm
content: Quote from: idpromnut on December 12, 2014, 04:10:33 pmMost broadband RF transformers for MF/HF bands are made using ferrite cores because the high permeability means that fewer turns are needed. This makes it easier to wind several wires on the same core, and minimizes problems with resonant problems in the windings. A good rule of thumb is to make the inductive reactance of the windings be 4-5x the impedance of the circuit that they're being used in.
How about XP-Pen Star05 drawing tablet for Photo Retouching - Page 1
Forum section: electronics / beginners

author: penglai
author_rank: Newbie
timestamp: April 17, 2018, 09:38:28 am
content: Hello guysI've been drawing traditionally ever since I was young. I am at an intermediary stage, according to me. I have been drawing digitally for 3 years now. I'm a little above the amateur stage I'd say.I want to get a drawing tablet now(The previous one wasn't meant for drawing. But it had display.)I am looking for a non-display type. So, I did a little research. Went through most of XP-Pen's products. And I liked the stars line.I went through the specifications. Draw, Art, Photo and Comic.I liked Comic and Art. I'm considering about buying XP-Pen Star 05 (https://www.amazon.com.au/XP-Pen-Star05-Wireless-Graphics-Battery-free/dp/B01MAZ5FDL). But the reviews section had many negative reviews. So, I wanted to ask you artists for advice.Also, any good drawing programmes for drawing and a different one for 2D animation? Both free and paid?I've been using Sketchbook Express, Autodesk Sketchbook and Artrage like, Art Flow, Art Rage on the previous tablet and Krita and Paint Tool sai on PC. Sketchbook ex used to be my favourite.Thanks for reading! Awaiting your replies.

author: Mr. Scram
author_rank: Super Contributor
timestamp: April 17, 2018, 09:41:24 am
content: Assuming you're working on Windows, have a look at Leonardo. I like the features it's offering, like the infinite canvas. I'm not affiliated in any way.https://www.getleonardo.com/
How accurate does it really need to be? - Page 1
Forum section: electronics / beginners

author: aswallace88
author_rank: Newbie
timestamp: June 27, 2019, 07:43:16 pm
content: I've recently started designing and building circuits, and to this end, I've gotten some tools that will help me understand what's going on. I got a digital oscilloscope (Siglent SDS1052DL+) and I happened upon an old Tektronix 463A for a reasonable price. They both power on and both seem to measure pretty well. The only issue is that the last proof of calibration I have for the 463A is from 1984. I want to calibrate it, and Tektronix will calibrate it for me but it'll cost $190, assuming there aren't any broken or worn out parts that need replacement. Can I calibrate it myself and get close enough for my hobby work seeing as it seems to be working correctly, or would I be better off sending it off to Tektronix and shelling out the money to make sure it's done to the nth degree?

author: bob91343
author_rank: Super Contributor
timestamp: June 27, 2019, 07:51:55 pm
content: Why do you need a calibrated unit? Once you answer that you can answer your main question.To calibrate an oscilloscope you only need an accurate voltage and an accurate time or frequency.The oscilloscope has a calibrator so you can just verify that.Nearly any cheap DMM is more accurate than an oscilloscope for voltage so you can compare with that. Frequency is easy too; even the power line is close enough. The 60 Hz line is 16-2/3 milliseconds per cycle.Chances are the units are just fine as is and don't need calibration. You don't measure stuff precisely with those instruments anyway; other gear is for that.

author: David Hess
author_rank: Super Contributor
timestamp: June 28, 2019, 08:15:13 am
content: First check the 463A against voltage, time, and transient response references to see if calibration is even required.The chances are only the gain adjustments for vertical and horizontal deflection are required.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 29, 2019, 06:59:46 am
content: In most cases one does not need a calibrated scope. The main purpose of calibration is a check that the instrument is still working oK and some commercial uses can need thus for legal reasons. Especially for a scope such a test is relatively easy and for hobby use it is a good point to really learn how to use the scope and know it's limits. One may not get all the details a good cal lab could check (e.g. divider compensation, gain flatness).Even if one really want's an official cal paper, one would do a first test anyway before sending it in - this is especially true for hobby use where time is not that expensive.A scope is usually not that accurate anyway, so that adjustments (e.g. gain, time scale) may not be needed, even after many years. SOme adjustments (e.g. divider compensation) are tricky and it may be better to just leave it as is unless one really knows how to do it and has the right instruments.
How adding a capacitor reduces the signal gain to 1 in OPAMP - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: October 26, 2020, 07:14:48 am
content: Here I can't understand how adding a capacitor reduces the signal gain to 1?

author: greenpossum
author_rank: Frequent Contributor
timestamp: October 26, 2020, 07:21:08 am
content: Not the signal gain, the DC gain, as the sentence says.

author: khatus
author_rank: Regular Contributor
timestamp: October 26, 2020, 07:22:25 am
content: yes but How?

author: greenpossum
author_rank: Frequent Contributor
timestamp: October 26, 2020, 07:25:39 am
content: The capacitor blocks the DC to ground so the voltage at the - input = output voltage so the output will follow the + input, hence DC gain of 1. But for AC the capacitor is a path to ground so there is a voltage divider for AC.

author: rs20
author_rank: Super Contributor
timestamp: October 26, 2020, 07:30:59 am
content: I'm just basically restating what greenpossum said, but doing so just on the off chance a slightly different perspective helps...If we want to know the behaviour of the circuit at DC, we can observe that capacitors block DC and therefore we can delete them from the circuit (replace with open circuit). At that point, R1 is pointing nowhere, so it can be deleted as well (it has no effect on the circuit anymore). And what you're left with at that point is the standard non-inverting voltage follower circuit (with a 18k feedback resistor), which by definition has a gain of 1 (voltage follower = gain of 1).
How are MPNs chosen? Is there any guarantee of uniqueness? - Page 1
Forum section: electronics / beginners

author: matthuszagh
author_rank: Frequent Contributor
timestamp: December 22, 2024, 07:40:20 pm
content: Do manufacturers of electronic components select their own part numbers (MPNs), or are these selected by an independent body? Is there any guarantee that part numbers are unique? If so, are there any permitted exceptions to uniqueness? For example, if I search 2N2484 on mouser I see a number of devices from different manufacturers with the same part number. In this case, I could see that it might be deemed permissible for different manufacturers to use the same part number if the datasheets specs are identical.Actually, in the example I gave, it seems 2N2484 is covered by MIL-PRF-19500/376. So, maybe any components that meet those specs can be identified as 2N2484.

author: TimFox
author_rank: Super Contributor
timestamp: December 22, 2024, 10:25:04 pm
content: The 2N- numbers were registered with JEDEC."JEDEC originally stood for Joint Electron Device Engineering Council, but it's now known as the JEDEC Solid State Technology Association." (their website)The registration includes a datasheet that parts with that exact number must meet.This originated in the vacuum-tube days. "In 1924, the Radio Manufacturers Association (which later became the Electronic Industries Association) was established. In 1944, the Radio Manufacturers Association and the National Electronic Manufacturers Association established the Joint Electron Tube Engineering Council (JETEC), which was responsible for assigning and coordinating type numbers of electron tubes." (ibid.)

author: Konkedout
author_rank: Frequent Contributor
timestamp: December 22, 2024, 10:53:57 pm
content: I suspect that the JEDEC numbers are declining in use and importance. I think that they apply only to discrete devices (not ICs). Even among discrete semiconductors, I do not think that many new ones are getting JEDEC designations. This means that companies are making their own part numbers.When I was working recently for a military/aerospace company, we used some JEDEC designated discrete components but our ICs were not JEDEC. I think we had some non-JEDEC discretes also...but my memory there is uncertain.If I wanted to sell a semiconductor designated as Konkedout271B I do not think that anyone would stop me.

author: ejeffrey
author_rank: Super Contributor
timestamp: December 22, 2024, 11:47:48 pm
content: Other than the 1N and 2N designations, many semiconductors have manufacturer prefixes such as LM, AD, TL, MC... This helped avoid accidental conflicts. Of course consolidation in the semiconductor industry means most of those are now the same handful of companies, but they still often use the same designations based on the acquired teams and product lines.
How are the ESD or antistatic properties of plastic ESD packaging boxes checked? - Page 1
Forum section: electronics / beginners

author: rogi23
author_rank: Newbie
timestamp: October 15, 2024, 02:25:55 pm
content: Hello everyone,I am interested in whether plastic ESD packaging boxes need to be checked for ESD or ANTISTATIC PROPERTIES, apart from surface resistance, and by measuring the electrostatic field they produce?Is measuring the electrostatic field they produce by manipulating them necessary?Thanks in advance.
How are TV remote docking station battery contacts wired to prevent a short? - Page 1
Forum section: electronics / beginners

author: dparson
author_rank: Newbie
timestamp: December 06, 2014, 07:57:29 pm
content: Hi all, can anyone explain how the battery contacts work on a device with a battery charging docking station? I have a TV remote control similar to the one pictured with one of these docking stations and I can't understand why there is no voltage on the gold contacts on the remote, but when you place it into a docking station the battery within it can be charged.I was working on my own project with a small 2 pin modular contact but realized there is something special going on with the remote since you can short the contacts on the remote and no current flows. How does one add this feature to a 2 pin contact that's used to charge a battery? Thanks for any help!- Dave

author: Zepnat
author_rank: Regular Contributor
timestamp: December 06, 2014, 08:19:20 pm
content: It'll probably have a battery charger IC between the connector and battery.Something like the TP4056, which is designed to prevent power coming out of the battery back to the charge socket.

author: Richard Crowley
author_rank: Super Contributor
timestamp: December 06, 2014, 08:25:24 pm
content: You kids with your new-fangled integrated circuits!It could be something as simple and prosaic as a diode!

author: SeanB
author_rank: Super Contributor
timestamp: December 07, 2014, 06:47:58 am
content: Very likely a bridge rectifier, and the base has a 6VAC current limited ( either from using a transformer with very poor regulation and a very thin secondary winding with high resistance or with an external resaistor or PTC thermistor) output, that is then used to charge the battery either with a resistor or a charge controller.Looks like your remote probably has a charge controller, and probably has a lithium pouch cell inside to power it.

author: dparson
author_rank: Newbie
timestamp: December 09, 2014, 04:16:11 am
content: Ah I see, the remote does have a charge controller, the base station has 8.6VDC on it's pins and they are recessed to prevent shorting out. The remote's pins sit into the base station and that's how it all works. Thank you all!

author: ConKbot
author_rank: Super Contributor
timestamp: December 09, 2014, 01:49:53 pm
content: 1/10-1/20 C or less constant(ish) current source, and a diode in series with 2 Ni-Mh cells. And could be itWith lithium polymer cell, an integrated charge controller (i.e. max1551 ) would be easy.
how bad are unleaded/leaded joints? - Page 1
Forum section: electronics / beginners

author: nrxnrx
author_rank: Unknown
timestamp: February 01, 2018, 05:18:54 pm
content: Hi!A friend has asked for help modifying one of his music boxes (korg volca beats) by replacing some resistors and caps and maybe soldering some components in parallel with the existing ones. As far as I can tell from pictures, it's 0805/0603 surface mount components.I don't have any lead-free solder. How brittle is a joint on a 0805 component made of 63/37 mixed with "Sn96.5 Ag3.0 Cu0.5"1in equal proportions ? How would two such resistors on top of each other (ignoring power dissipation) fare being thrown around in a bag for a few hours?Is it worth the trouble of removing all solder and maybe replacing components instead of soldering resistors/capacitors in parallel?--1. I don't know what solder Korg's contractor used. The above is just a lead-free solder mixture Pace's website told me is common.

author: NEYi
author_rank: Contributor
timestamp: February 01, 2018, 05:44:20 pm
content: Personally, I prefer removing the component, wicking up all the old solder and applying new leaded one.This way you'll get mirror-like joints that won't crack in like forever.Though, in general all these "aerospace rules" on soldering aren't that important, even crappy looking joint with mixed solder most certainly will do the job and won't crack.Just make sure it's was soldered with some kind of flux, personally I prefer rosin diluted in isopropanol.P.S. You don't have to throw away the removed part, unless it's obviously damaged.Components on top of each other work okay.

author: helius
author_rank: Super Contributor
timestamp: February 01, 2018, 05:52:02 pm
content: According tohttp://publications.npl.co.uk/npl_web/pdf/matc85.pdf,mixtures of traditional tin-lead and lead-free alloys do not result in brittler joints. They can cause separation of the joint as it cools, which can in extreme cases destroy pads on the board. A 50%-50% mixture of SAC305 and Sn63 is actually less brittle than a Sn62Pb36Ag2 pure joint.

author: David Hess
author_rank: Super Contributor
timestamp: February 01, 2018, 07:30:51 pm
content: Quote from: helius on February 01, 2018, 05:52:02 pmSn62Pb36Ag2 is pretty tough so I wonder what the story is there. I suspect its tensile strength and adhesion was so high that it was ripping the end terminations off.If I am reading that paper correctly, all but one of the mixtures were better than the two pure alloys they tested. Unfortunately they only tested the pure alloys of SnCu and SnPbAg and did not include SnPb or any of the others which makes me question all of their results.

author: stj
author_rank: Super Contributor
timestamp: February 02, 2018, 01:57:55 am
content: i'v never seen it cause a problem,what you do want to avoid is mixing different fluxes.so clean the area before you solder it if there is any old flux around.
How can an AC motor run fast? - Page 1
Forum section: electronics / beginners

author: rea5245
author_rank: Frequent Contributor
timestamp: July 20, 2015, 04:26:05 pm
content: Hi,I have a store-bought digital flip clock that runs off a 60 Hz AC motor (there's a manufacturer's sticker on it that confirms it's "60Hz"). It's old - a few decades - so I could understand it having problems. But the problem I'm seeing is that it runs fast. It advances the time by one minute every 55 seconds or so.Using a Kill-a-Watt meter, I've confirmed my line frequency is 59.9 Hz. How is it possible that an AC motor would run fast? If I understand AC motors correctly, even a noisy power line shouldn't cause such a thing.Thank you,Bob

author: IanB
author_rank: Super Contributor
timestamp: July 20, 2015, 04:39:35 pm
content: Did you ever see it keeping correct time? Was there some event when it stopped working properly?Such clocks would use a synchronous motor that is locked to the AC frequency. If the clock is not keeping time it seems that somehow the motor could be faulty.

author: AG6QR
author_rank: Frequent Contributor
timestamp: July 20, 2015, 05:03:21 pm
content: There is a gear train between the motor and the things it is driving. Is there any chance someone "repaired" it at some time in the past and swapped a gear for one containing a different number of teeth?Not all AC powered clocks use synchronous motors, though that's a very common way to do it. AC synchronous motors give off an audible hum at the mains frequency. Can you hear the hum in this clock? Are you sure it's got an AC synchronous motor?Is its speed of running consistent? Or is it somewhat erratic?

author: Tomorokoshi
author_rank: Super Contributor
timestamp: July 20, 2015, 05:06:17 pm
content: The speed of a synchronous motor is:Ns (RPM) = 120 * f / pf = line frequencyp = number of poleshttp://en.wikipedia.org/wiki/Synchronous_motorIf a pole pair shorts together, then p is decreased, which would increase the speed.You might be able to hear a beat frequency as the rotor passes by the shorted poles.

author: G7PSK
author_rank: Super Contributor
timestamp: July 20, 2015, 08:35:11 pm
content: Most clock motors only have one coil so any pole shorting will be of the mechanical variety more likely that a pole or two is missing from the motor, a finger broken off in the past but check for iron dust in the motor as that is what would short the poles.

author: Fank1
author_rank: Regular Contributor
timestamp: July 20, 2015, 11:33:33 pm
content: Clock motors usually have a "shading coil" it's just one loop of copper wire.Check to see if it has become open.
How can I (re)-calibrate my Hakko FX-888D temperature?  (re: inexpensive?) - Page 1
Forum section: electronics / beginners

author: sofakng
author_rank: Regular Contributor
timestamp: February 02, 2021, 07:16:36 pm
content: I've been having some problems with the Hakko FX-888D not melting solder properly, and I'm pretty sure at some point I accidently entered the calibration menu.It looks like the Hakko has a temperature calibration unit (Hakko FG-100) but it's very expensive for a one-time use.Should I purchase a cheap knock-off unit? Does anybody have a unit they can lend me? Should I use a K-probe (?) or similar with my Fluke 87V meter?

author: sofakng
author_rank: Regular Contributor
timestamp: February 02, 2021, 10:44:19 pm
content: Can I purchase something like the Fluke K-probes? (Fluke 80AK-A or Fluke 80BK-A?)...and then maybe use something like the Hakko 191-212 (replacement sensors) ?Is there a better option?

author: wraper
author_rank: Unknown
timestamp: February 02, 2021, 10:48:06 pm
content: You don't need to recalibrate, just reset to factory settings.https://kb.hakkousa.com/Knowledgebase/10599/How-do-I-reset-the-HAKKO-FX888D-back-to-factory-default-settings

author: sofakng
author_rank: Regular Contributor
timestamp: February 02, 2021, 10:54:27 pm
content: Thanks! I've already performed the reset, but I've read that doesn't properly reset the calibration? I'd also like to verify it's accurate anyways just to make sure.
How can i add tracking to my PSU Project - Page 1
Forum section: electronics / beginners

author: namster
author_rank: Regular Contributor
timestamp: February 10, 2018, 03:27:26 pm
content: Good Morrning , i work on symetrics PSU and for that i have used the topology of HP Application Note (In Attachment ) that work correctly and now i want to make another output with tracking Option I have tried but its not work ! in schematics i use R17 for varying Vout and R44 for -Vout how can i vary symmetrically Vout and -Vout with only R17 ?
How can I build a 120v ac voltage source with a maximum output current of 5mA? - Page 1
Forum section: electronics / beginners

author: AMWallace123
author_rank: Newbie
timestamp: January 30, 2018, 10:24:53 pm
content: Im working on a project that requires a 120v ac voltage source with a maximum output current of 5mA. What type of circuit or component can i use to accomplish this? Thanks your help

author: danadak
author_rank: Super Contributor
timestamp: January 30, 2018, 11:59:57 pm
content: This might be informative -http://ww1.microchip.com/downloads/en/AppNotes/00954A.pdfhttps://www.edn.com/design/power-management/4418393/AC-power-your-circuit-without-a-transformerhttps://circuitdigest.com/electronic-circuits/transformerless-power-supplyhttps://hackaday.com/2017/04/04/the-shocking-truth-about-transformerless-power-supplies/Regards, Dana.

author: Cliff Matthews
author_rank: Unknown
timestamp: January 31, 2018, 04:25:54 am
content: That's quite a small current without details on usage, safety requirements, tightness of regulation and AC frequency. So assuming economy and 50/60Hz (not frequencies far beyond), one could back-to-back couple two <100ma wall-warts with some current limiting PTC's between. I'm not big on math and often prefer quick mock-ups, so let's leave it open for others to comment. Almost forgot,welcome to the forum!

author: Zero999
author_rank: Super Contributor
timestamp: January 31, 2018, 10:30:47 am
content: You forgot to say what your input voltage is.If it's 120VAC, then all that's needed is a capacitor or resistor, to give the correct impedance, to limit the current to 5mA.If it's 240VAC, then use two resistors or capacitors of the same value and correct impedance to limit the current to 5mA.If it's DC, then you need an oscillator and amplifier to drive a transformer to get the correct voltage. Current limiting can be implemented in the amplifier's output stage.