hybridfree/eevblog-posts huggingface dataset:
What is the role of this circuit? - Page 1
Forum section: electronics / beginners

author: fabiodl
author_rank: Frequent Contributor
timestamp: November 20, 2020, 10:56:39 am
content: In thissc-3000 schematicpage 6 I found the attached circuit. What is its purpose? does it only shift down the voltage?

author: TimFox
author_rank: Super Contributor
timestamp: November 20, 2020, 02:26:21 pm
content: It looks like a circuit to emulate a Zener diode using the PNP transistor to pass the current, but you need to show more of the total circuit to make clear what goes in and what goes out.

author: Cerebus
author_rank: Super Contributor
timestamp: November 20, 2020, 03:24:08 pm
content: It gets clearer if you get more of the circuit:(there are 3 channels like this, this is the top one and is a little clearer than the one the OP posted but is functionally identical)and it gets clearer still if you redraw it in a slightly more classic form than the original draftsman:Now the output transistors look like a Sziklai complementary feedback pair, with the zener inserted to do some level shifting. Either the original designer has done something moderately clever to establish a required set of DC conditions on the output, or they got their DC bias conditions in a real mess earlier in the chain and had to use the zener to rescue themselves.TR3 is an emitter follower, TR4 works with it to provide more current gain and a little more voltage gain (it gets closer to the ideal gain of 1 for an emitter follower). TR4 also provides TR3 with negative voltage feedback (by altering the Vbeof TR3) and so also improves the linearity of the emitter follower. TR3 and TR4 work together to act as a compound transistor. Read up onSziklai pairsif you don't understand this bit.The long and the short of it is that this is just a rather unusual output amplifier.

author: fabiodl
author_rank: Frequent Contributor
timestamp: November 23, 2020, 11:29:19 pm
content: I was wondering if they used the nonlinearity of the diode in any way, but I am now more convinced that all the zener does is shifting the dc,thank you!
what is the smallest transformer one can use for an inverter circuit. - Page 1
Forum section: electronics / beginners

author: Artisticano.black
author_rank: Newbie
timestamp: July 01, 2020, 09:25:02 pm
content: Hi guys, I am working on a project where I want to step up a 3.7 volt DC supply from a 500mah lipo Battery into voltages as high as 250V, so essentially I am looking at making an inverter but the key constraint is the size aspect of it. I want to make it as compact as possible. With dimensions of around 15X15X10 mm. I was wondering if I can use an EE10 transformer for the job. Also if you can share the schematics for some sort of inverter or maybe an EMP device that might do the above mentioned task.
What is the standard TO220 footprint for "bent centre leg"  fitting? - Page 1
Forum section: electronics / beginners

author: ocset
author_rank: Super Contributor
timestamp: November 03, 2018, 10:28:41 am
content: Hi,We are using a TO220 NFET in our 60W offline (240vac) flyback smps.We wish to bend out the TO220 centre leg to increase clearance on the PCB.This bending will doubtless be done by a machine eventually.What is the standard "bent leg TO220" footprint? (ie the dimensions and PTH to PTH spacings that the "leg bending machines" most commonly work to)Surprisingly, this didnt say...https://www.infineon.com/dgdl/Infineon-Package_recommendations_for_assembly_of_Infineon_TO_packages-AN-v01_00-EN.pdf?fileId=db3a30431936bc4b011938532f885a38The following says 1.75mm plus 1 to 2 times the leg thickness.....but is there a standard?http://www.irf.com/technical-info/appnotes/an-1031.pdfAlso, the AN1031 doc has all three leads bent........this must be from some standard "bending machine" otherwise it would be too labour intensive. Do you know which machine is used?OK, found PN5050, hoep someone else finds this useful.https://www.olamefusa.com/e_spec_handtools.htm#PN505015Very expensive tool though.https://www.olamefusa.com/e_spec_handtools.htm#PN505015

author: hermit
author_rank: Frequent Contributor
timestamp: November 03, 2018, 06:53:44 pm
content: You might get a clue from this device. 7 pins and staggered.https://www.analog.com/media/en/technical-documentation/data-sheets/3081fc.pdf

author: floobydust
author_rank: Super Contributor
timestamp: November 03, 2018, 07:14:00 pm
content: SeeOn-Semi TO-220 case 340AXYou have to watch the bend radius so you don't stess the die or the leads. It's also another manufacturing step risking ESD damage.Ultimately the TO-220/D2PAK package is limited for high-voltage creepage/clearance for regulatory.Slots are also commonly used between the pads on the pcb.
[Sloved] What is the tequipment EEVBlog code? - Page 1
Forum section: electronics / beginners

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: October 16, 2023, 05:10:09 pm
content: Some time ago I stumbled onto a post talking about how their was a code for tequipment which, provided that it wasn't shared publicly, would remain valid indefinitely. Supposedly, you had to post and ask for it in the EEVBlog, and it was good for 10% off your hobbyist) purchase at tequipiment.Assuming that this is still going on, could someone please DM me the code as well?ThanksPS: The post was old so I do/did not want to add onto it.

author: edavid
author_rank: Super Contributor
timestamp: October 16, 2023, 05:58:47 pm
content: It's right here:https://www.eevblog.com/forum/testgear/eevblog-members-discount-at-tequipment/msg2085649/#msg2085649
What is the test output for? - Page 1
Forum section: electronics / beginners

author: DFliyerz
author_rank: Newbie
timestamp: November 19, 2014, 03:42:55 am
content: I have this bench power supply, and have been using it for experimenting with electrolysis. I didn't pay much attention to this part when I got it, but I'm now wondering what the "test" positive output does, and if it simply produces a massive 200V DC. Please help!

author: Kappes Buur
author_rank: Regular Contributor
timestamp: November 19, 2014, 06:28:09 am
content: To test an external voltage source (eg: battery).Mind the polarity, though.
What is the Theoretical Maximum Refresh Rate of TFT LCD Displays? - Page 1
Forum section: electronics / beginners

author: SwaziLande
author_rank: Newbie
timestamp: May 08, 2019, 01:33:39 am
content: I just picked up a free ViewSonic VP720b today. It's 1280x1024 TFT AMLCD, so not the highest resolution, but I was hoping to modify, or all together replace, the mother board so that it can increase the refresh rate to something higher than 85Hz. Before anything I wanted to know if that was even possible.I know about IPS panels, but I don't know if the reason they can have such a high refresh rate is due to the technology in the display it's self or the display controller. if it is because of the display controller, I was thinking I could maybe custom build a mother board to make the display have a higher refresh rate. Probably overkill, but I thought it might be a fun project.The current Flat Panel Display Controller is and old Realtek RTD2363 which I couldn't even find a datasheet for. But I could find one for an RTD2525 which seemed like the later evolution of the 2363 (https://cdn.datasheetspdf.com/pdf-down/R/T/D/RTD2525-Realtek.pdf). I'm not sure if this helps but the display it's self has a 30 conductor FFC. Thanks for any input, or for telling me I'm chasing unicorns.

author: pwlps
author_rank: Frequent Contributor
timestamp: May 08, 2019, 05:33:22 pm
content: The response time depends on the technology of the display itself. Apparently IPS are not the fastest:https://www.trustedreviews.com/news/ips-vs-tn-vs-va-gaming-performance-colour-explained-2948955
what is the use for 2 cathodes in an triode? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: February 02, 2020, 12:50:40 am
content: what would someone use 2 cathodes for?I found this 6Г7 tube that has 2 cathodes and don't see it useful.

author: schmitt trigger
author_rank: Super Contributor
timestamp: February 02, 2020, 12:52:35 am
content: It would be very interesting if you post the tube schematic.Perhaps as a mixer?

author: ArthurDent
author_rank: Super Contributor
timestamp: February 02, 2020, 01:18:19 am
content: That is a multipurpose tube with one cathode, 2 anodes, plus a triode. Tubes like this were used the diodes for the detector and automatic volume control (AVC) and the triode for the 1st audio amp in a receiver. Here is a similar tube.https://frank.pocnet.net/sheets/093/6/6SQ7.pdf

author: ArthurDent
author_rank: Super Contributor
timestamp: February 02, 2020, 01:39:04 am
content: You are not understanding what I have said or the datasheets have described. Here is the tube redrawn to make it obvious.
What is the use of these extra spacers in these female banana connectors - Page 1
Forum section: electronics / beginners

author: BreenBoks
author_rank: Newbie
timestamp: January 23, 2023, 12:58:10 pm
content: Bom dia!This has been bugging me for quite some time. I have these real cheap Chinese female banana connectors which consist of 7 (!) parts. What it the recommended way of mounting these, and what is the use of these two extra plastic parts?Thanks for your time!

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: January 23, 2023, 01:22:09 pm
content: You can use them to mount the banana jacks to a metal chassis but still not make electrical contact to the chassis using those spacers.

author: BeBuLamar
author_rank: Super Contributor
timestamp: January 23, 2023, 01:22:37 pm
content: To make sure the metal parts don't touch the panel that you mount it on.

author: BreenBoks
author_rank: Newbie
timestamp: January 23, 2023, 01:26:48 pm
content: Of course! Making boxes with my 3d-printer made me forget there are other materials besides PLA! Thanks

author: Stray Electron
author_rank: Super Contributor
timestamp: January 23, 2023, 02:55:01 pm
content: They include two nuts for a reason. Use one nut and the flat washer to mount the jack and tighten it down. Then install the wire lug (wired to your circuit of course) and then secure that with the second nut. That will enable you to remove the wire lug and change your circuit or to repair it, without having to dismount the entire jack.

author: BillyO
author_rank: Super Contributor
timestamp: January 23, 2023, 03:23:01 pm
content: I have also used them with plastic panels by putting both on the outside to reduce how far the jack extends into the case. But the real reason for their existence is as mentioned.
What is the value & voltage ratings of this capacitor - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 06, 2017, 05:10:33 am
content: What is the value & voltage ratings of this capacitor1. Attached find a pic of a board. This is capacitive supply board & two capacitor in series are used. The boards works upto 440V.2. What is capacitance & voltage rating of this capacitor.Is cap = 550uF& voltage rating=??3. H684K C550MFF4Not sure if its C in first line end.

author: David Hess
author_rank: Super Contributor
timestamp: February 06, 2017, 05:26:23 am
content: 684K means 68 * 10^4 picofarads or 680,000 picofarads or 680 nanofarads or 0.68 microfarads. I think 550 is the DC voltage rating.

author: tautech
author_rank: Super Contributor
timestamp: February 06, 2017, 05:36:55 am
content: Quote from: David Hess on February 06, 2017, 05:26:23 amThe K has nothing to do with the absolute value, it is the value tolerance indicator, in this case+10%http://www.robotoid.com/appnotes/electronics-capacitor-markings.html

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 12, 2017, 05:56:30 am
content: Thanks for your reply.I have to make a capacitive supply from 440Vac to 9vdc & then regulator 7805.Will make & see the results. Tested using these capacitors it is working fine.But I will connect two 2.2uF,400V in series to be used for this since current requirement is bit more, cap as in attaced pic. SO that end capacitance is 1.1uF/800V.Though They are not safe since they are not X2 type. But I have seen them in so many boards, none of them had any problem due to capacitor or capacitor every busted.1. Are these two capacitor in series can withstand 440Vac. Since combined voltage value will be 800V. In ac 440Vac peak will be = 440*(2^0.5) = 622Vac. So I think I am well within limits?Theoretically for 800V max ac can be = 800V/(2^0.5) = 565Vac.2. What is voltage variation in these capacitors? is it +-10%?3. Which fuse value should be used in this? Max ac load comes out to 150mA. So I am placing 1A fuse.4. What is the MOV selection criteria for this.

author: deltalight
author_rank: Newbie
timestamp: February 12, 2017, 06:25:47 am
content: If I read your objective correctly, you are constructing a transformerless supply where the 2.2uF 400v film cap is in series with the A/C line (220VAC?).If this is the case, then you may want to use a Panasonic Class X sately film caps:ECQUA (Class X) Polypropylenehttp://datasheet.octopart.com/ECQ-UAAF684K-Panasonic-datasheet-22087606.pdfECQUL (Class X2) Metalized Polyesterhttp://www.farnell.com/datasheets/18742.pdfThe film structure in these caps is made in a matrix such that if it fails, it opens and doesn't short for sately reasons. Should be available from DK and Mouser.
What is the viability of a newbie being able to design this? - Page 1
Forum section: electronics / beginners

author: Jackster
author_rank: Frequent Contributor
timestamp: January 15, 2017, 09:08:43 pm
content: So I have this project where I need to design a PCB for a project.The designed is centred around a Arduino "ATmega328" and a couple 7 segment displays.I need to still have the USB part to program the micro controller.Will also need a lithium battery charger and a secondary input that is between 10-20v to power the whole thing.While I would love to just hand this off to someone, I don't really have the budget to do that so I am looking to design and get the PCBs made and components fitted on a run of around 50 units.I have been watching Dave's older videos on doing this and feel like it is possibly something I could do myself?Not really used circuit design software before. I have had a tinkle in CircuitMaker but it is a tad daunting looking at how much there is.I am guessing it is best done in baby steps?Tare apart the Arduino design and then design the drop down converter, then the charging circuitry.Thinking it would be best to look at stuff already made, like those charging circuits you can get off eBay and reverse engineer them into my design?(If that is allowed? Guessing most of these things are just straight off the PDF you get from the manufacture so no real problems there?)What my question is here, is if this is at all viable for someone just starting out.ThanksJack,

author: kripton2035
author_rank: Super Contributor
timestamp: January 15, 2017, 09:18:36 pm
content: I think you should find all arduino ready modules that fits your need.program it, discover how they work. make one protptype with ready made small boards, and breadboards.then, once it works, ( one big step for you) you can go to the next step: make your own pcb with only what you need on it.if you need 50 working units, better make one working first.also if you are stuck on a problem, I'm sure you will get help by coming on this forum and explaining it.

author: tautech
author_rank: Super Contributor
timestamp: January 15, 2017, 09:19:02 pm
content: On a similar vein is a reply in this thread along with some links to other PCB software:https://www.eevblog.com/forum/projects/pcb-etching-81228/msg1114208/#msg1114208

author: Jackster
author_rank: Frequent Contributor
timestamp: January 16, 2017, 08:38:58 am
content: Quote from: kripton2035 on January 15, 2017, 09:18:36 pmAlready got a prototype working using the Arduino Nano board. Though I have yet to program buttons or the wifi.My main problem is the power stuff. I am guessing there are open designs out there that people share that one could use?Or is it just a case of search though the forums as I am sure others have posted something similar.Quote from: tautech on January 15, 2017, 09:19:02 pmI remember doing this is school years ago xDProbably give it a go while I wait for PCB manufacture to make a test one and ship it.Thanks guys!
What is this(drip?) transducer?  - Page 1
Forum section: electronics / beginners

author: soldar
author_rank: Super Contributor
timestamp: September 01, 2019, 08:15:35 am
content: I found in the trash, near a clinic, these two identical transducers. They have connections for a tube and an electrical connection with four conductors. They look like they have some kind of optical detector.I suspect the most likely use is they detect drops as they fall OR they might detect liquid level in the chamber. Maybe those serum bags you see in movies.If you search Google images for serum drip transducer you can find similar-looking things.Before I tear into them and destroy them I wonder if anyone is familiar with them and what kind of electrical circuit they might have. I wonder if the optical transducer can be put to any useful use. Maybe a drip watering system for delicate plants

author: Gyro
author_rank: Super Contributor
timestamp: September 01, 2019, 09:56:28 am
content: I think it is an optical liquid presence detector. The presence or absence of liquid in the tube is going to change its refractive index, there's no space in there for anything to drip.The term 'drip' is a generic term for IV bad infusion systems. The actual drip chamber is much bigger, having space for a small volume of fluid and the pipe where the drips emerge from at the top. My best guess is that it is used as a 'bag empty' sensor (end of infusion alarm).EDIT: Looking closer, there does look to be a very small nozzle in the RH end of the left hand unit in your photo - this might just possibly cause a drip if maintained vertical (not sure how practical that would be in practice).

author: soldar
author_rank: Super Contributor
timestamp: September 01, 2019, 01:12:52 pm
content: I think it is inserted in the vertical hanging tube and it probably detects level in the chamber where the liquid drips. The question is how is the best way tp test the contacts. I assume two are for power and two for signal. What is the best way to approach an investogate?

author: Rerouter
author_rank: Super Contributor
timestamp: September 01, 2019, 01:20:13 pm
content: starting point would be diode check, most chips ESD diodes mean there is going to be a diode drop between each supply and the output. so whichever pair has 2 drops is likely the supply connections.

author: soldar
author_rank: Super Contributor
timestamp: September 17, 2019, 11:07:21 am
content: I did a quick resistance measurement but it does not tell me anything obvious.At the same time I observe that, even though it is a proprietary connector, it has four wires with the standard USB colors and I see a tiny IC inside. What are the chances that it is USB? I do not want to risk connecting it to a computer USB port. Is there some non-risky way to test? Other ideas?
What is this 1982 circuit board made of? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: June 24, 2014, 08:13:38 pm
content: I finally removed the shielding from an old General Instruments / Electrohome satellite receiver from 1982 (first IF Amplifier IF-I Made in Canada) and see that it's all this shiny metallic looking stuff. It almost looks like thick aluminum foil. I dabbed my flux pen on it and was able to solder to it quite well and of course all the components on this board are surface mounted to this material.The back of this board is regular copper with green a coating.What is this stuff?Is it basically a big metal sticker transferred onto FR-4 like material?

author: chrissmeuk
author_rank: Contributor
timestamp: June 24, 2014, 08:38:06 pm
content: Possibly FRP with copper. It looks like it has just been tinned after etching hence the appearance.If you don't need it or it's duff, scratch some of the tinning with a flat blade and see if it's copper underneath.

author: Mr.B
author_rank: Unknown
timestamp: June 24, 2014, 08:38:55 pm
content: Looks like roller tinned FR-2 to me...

author: dentaku
author_rank: Frequent Contributor
timestamp: June 24, 2014, 09:03:53 pm
content: Aha.Yup, I scraped the top layer off and it's copper underneath.

author: Fank1
author_rank: Regular Contributor
timestamp: June 24, 2014, 09:55:09 pm
content: I believe it was called REXOLITE used mainly for high frequency stuff.Not a sticker, just plated copper after it was etched.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 26, 2014, 08:01:54 am
content: Quote from: dentaku on June 24, 2014, 08:13:38 pmJust tinned copper---& the board material? FRP of some kind,bit different,& slightly cruddier than most."Very Electrohome",they used this board material in all their Picture Monitors,too.

author: dentaku
author_rank: Frequent Contributor
timestamp: June 26, 2014, 01:10:02 pm
content: Quote from: vk6zgo on June 26, 2014, 08:01:54 amIt's kinda lumpy and you can see the fibers in it so it is strange looking stuff. It also smells very different than regular boards when you cut into it. Regular boards smell like horse manure but I'm not sure if that's the material itself or if it the smell of green solder mask.
what is this 1n760 diode? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: December 29, 2019, 04:40:40 pm
content: so I am trying to make a modernized, and cheaper version schematic of the 'dual rectifier' amplifier. but I can't seem to find anything about this 1n760 diode in the shematic, also what is the value of that resistor that has '22?' next to it? I am not sure cause it has another value next to it.also, those caps are 4 10000uF caps by my understanding, yes!?

author: george.b
author_rank: Frequent Contributor
timestamp: December 29, 2019, 04:57:49 pm
content: Quote from: ELS122 on December 29, 2019, 04:40:40 pmJudging by the voltages, that should be a 4.5V Zener. References to 1N760 that I could find on the internet are to a Germanium diode. 1N761-1N769 are zeners, so the type number might be wrong on the schematic.Quote from: ELS122 on December 29, 2019, 04:40:40 pmSomeone seems to not have been happy with the original 39 ohms value and annotated a different value? DunnoQuote from: ELS122 on December 29, 2019, 04:40:40 pmCorrect.

author: mikerj
author_rank: Super Contributor
timestamp: December 29, 2019, 10:04:19 pm
content: It's actually a 1N750, the schematic isn't very clear but you can see the flat top of the five. The 1N750 is a 4.7v, 500mW zener so the voltages marked on the schematic are approximate.

author: george.b
author_rank: Frequent Contributor
timestamp: December 29, 2019, 11:56:09 pm
content: Quote from: mikerj on December 29, 2019, 10:04:19 pmHa, well spotted!
What is this 2 lead part? - Page 1
Forum section: electronics / beginners

author: jpyeron
author_rank: Regular Contributor
timestamp: May 30, 2020, 01:41:31 am
content: While cleaning up my lab bench, I ran across these components.They are small, black, teardrop shaped, without any labeling.Thoughts?

author: floobydust
author_rank: Super Contributor
timestamp: May 30, 2020, 02:05:51 am
content: They look like bead thermistors. You can measure their resistance and see if it changes a lot with temperature.

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: May 30, 2020, 02:15:48 am
content: Yeah, my bet is on generic 10 kOhm NTCs. Check your eBay/AliExpress/whatever purchase history ... works great for mystery parts.

author: jpyeron
author_rank: Regular Contributor
timestamp: May 30, 2020, 02:21:51 am
content: That makes sense, a few years ago there was a project using that here. I'll test when back at the bench.Thanks

author: TimFox
author_rank: Super Contributor
timestamp: May 30, 2020, 02:52:57 am
content: Connect an ohmmeter, then squeeze hard between your thumb and forefinger.

author: jpyeron
author_rank: Regular Contributor
timestamp: May 30, 2020, 06:46:36 pm
content: once I had the "thermistor" keyword to search by it narrowed it down.Amico 100 Pcs 10K Ohm 3% Temperature Measurement NTC Thermistors MF52-103Amazon ORDER PLACED - November 7, 2012 (sigh, need to organize more often)
What is this?  - Page 1
Forum section: electronics / beginners

author: jbrewton
author_rank: Newbie
timestamp: January 30, 2014, 09:05:02 pm
content: First time poster long time watcher:Can someone tell me what this is?

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 30, 2014, 09:07:20 pm
content: Looks like a polyester film capacitor.

author: xygor
author_rank: Regular Contributor
timestamp: January 30, 2014, 09:24:45 pm
content: A polyfuse.http://www.digikey.com/product-detail/en/600R150-RAF/600R150-RAF-ND/1211303

author: SeanB
author_rank: Super Contributor
timestamp: January 30, 2014, 09:29:57 pm
content: PTC fuse, 150mAhttp://www.littelfuse.com/products/resettable-ptcs/~/media/electronics_technical/datasheets/resettable_ptcs/littelfuse_ptc_600r_datasheet.pdf

author: jbrewton
author_rank: Newbie
timestamp: January 30, 2014, 09:35:43 pm
content: Thank you xygor and SeanB.This will make for some interesting experiments.

author: vigsgb
author_rank: Contributor
timestamp: January 30, 2014, 10:30:25 pm
content: I was asking the same question to myself the other day while I was exploring an old PCB out of a microwave. My component was a Varistor as the PCB had a Z symbol on the PCB under the component. Your picture looks like the same type of component.. Maybe a PolyFuse is the same as a Varistor?
What is this? - Page 1
Forum section: electronics / beginners

author: supercar14
author_rank: Newbie
timestamp: April 01, 2015, 05:09:51 am
content: Hi all. I'm new to the electronics hobby and just recently got a soldering kit and started scrapping stuff for parts. I was recently taking apart an old CRT monitor (don't know the make or year) and found this.I'm thinking it's some kind of inductor but there was no designator on the board. I've never seen anything like it before. If anyone knows what it is I would be most appreciative.Thanks

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 01, 2015, 05:34:41 am
content: Yes, it is an inductor. The several wires twisted together are a high-current form of "Litz-wire", which is used to handle high currents at high frequencies.http://en.wikipedia.org/wiki/Litz_wireIt would have been helpful to see down inside the middle. It may be hollow, or it may have an adjustable "slug" to "tune" it, or it may have a rod of ferrite as a core.http://en.wikipedia.org/wiki/Ferrite_coreIt seems possible it came from somewhere in the horizontal sweep circuit, or perhaps in a switch-mode power supply (SMPS).

author: supercar14
author_rank: Newbie
timestamp: April 01, 2015, 05:55:56 am
content: Didn't even think to look in the middle. Yes it does have a slot in each end for an allen key. I'm not too familiar with how the old crt's work, so I don't really know what the board it was on was (I suppose I should have taken some pictures before I took it apart). It wasn't off the main board or with any power components, it just had some caps and resistors on it.That's all that's left of the board.Anyway thanks for the reply.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 01, 2015, 10:48:04 am
content: Looks like it was part of the extensive and extraordinarily fiddly kludge of circuits that enabled the old-school CRT to accurately shoot colors across the whole screen. Even on the most modern versions, there were literally dozens of adjustments to manipulate the three electron beams to hit only their proper (red or green or blue) phosphors on the face of the CRT. That board had several "trimmer resistors" (marked "VR.." for Variable Resistor). and that inductor was adjustable by using a plastic hexagonal "tuning wand" to move the ferrite slug back and forth (to increase or decrease the coupling between the two windings).
What is this? - Page 1
Forum section: electronics / beginners

author: gowf67
author_rank: Contributor
timestamp: May 28, 2015, 02:11:55 am
content: I removed this from an old board with some really old and large resistors. To my untrained eye it looks like a tunable air coil or is it just a plain old potentiometer? If it is a coil is there anyway to check the inductance? Thanks

author: Yansi
author_rank: Super Contributor
timestamp: May 28, 2015, 02:16:38 am
content: Nah. Just plane old wirewound pot.

author: c4757p
author_rank: Super Contributor
timestamp: May 28, 2015, 02:17:27 am
content: yup, standard, old-fashioned WW pot. Rather coarse winding, but standard nonetheless.

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 28, 2015, 02:17:47 am
content: It is an old-school wire-wound trimmer pot. Probably 100 ohms or lower.Not designed to be usable as an inductor.

author: gowf67
author_rank: Contributor
timestamp: May 28, 2015, 02:19:51 am
content: Looks like I over thought this LOL.
Delete Delete Delete - Page 1
Forum section: electronics / beginners

author: The_Almighty_Bacon_Lord
author_rank: Contributor
timestamp: July 11, 2016, 08:29:17 pm
content: Delete Delete Delete

author: bktemp
author_rank: Super Contributor
timestamp: July 11, 2016, 08:34:49 pm
content: It is a capacitor. It has the modified package type for reduced parasitic inductance (larger solder connection, smaller distance between pads).

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 11, 2016, 08:36:09 pm
content: I *think* it is a capacitor, and it looks like it is designed to have a low esr, that is why it looks turned 900.But I have no experience with this so I could be totally wrong

author: ataradov
author_rank: Super Contributor
timestamp: July 11, 2016, 08:38:57 pm
content: They are indeed low ESR capacitors.

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 11, 2016, 08:45:19 pm
content: Quote from: The_Almighty_Bacon_Lord on July 11, 2016, 08:44:19 pmYeah, that would be the thing to do.

author: ataradov
author_rank: Super Contributor
timestamp: July 11, 2016, 08:45:52 pm
content: Quote from: The_Almighty_Bacon_Lord on July 11, 2016, 08:44:19 pmNot at all.Quote from: The_Almighty_Bacon_Lord on July 11, 2016, 08:44:19 pmDo that, those are mostly bypass caps they don't really matter.

author: ataradov
author_rank: Super Contributor
timestamp: July 11, 2016, 09:33:03 pm
content: Quote from: The_Almighty_Bacon_Lord on July 11, 2016, 09:30:50 pmWith alcohol.Quote from: The_Almighty_Bacon_Lord on July 11, 2016, 09:30:50 pmDon't use excessive force. Those pads are not that easy to remove even if you wanted to. You are not gona damage them by gently rubbing them with alcohol.

author: ataradov
author_rank: Super Contributor
timestamp: July 11, 2016, 09:40:05 pm
content: Quote from: The_Almighty_Bacon_Lord on July 11, 2016, 09:38:17 pmOf course it will, otherwise entire electronics industry would have really tough time getting anything done

author: ataradov
author_rank: Super Contributor
timestamp: July 11, 2016, 09:48:07 pm
content: Watch your language.It would have turned on even without that cap.

author: ataradov
author_rank: Super Contributor
timestamp: July 11, 2016, 09:54:08 pm
content: Quote from: The_Almighty_Bacon_Lord on July 11, 2016, 09:50:51 pmI don't know how impressive it is. Those capacitors are providing local power bypass. If you have reasonably designed motherboard, then things will work (or at least try to boot) if you remove most or even all of them. They mostly affect system stability under varying load.
What is this?  - Page 1
Forum section: electronics / beginners

author: RyanG
author_rank: Regular Contributor
timestamp: September 01, 2017, 12:39:44 am
content: I took apart an old emergency light and this part was in it. I haven't found too much about it online. The only thing I saw was one site that suggested it might be an SCR.

author: KMoffett
author_rank: Regular Contributor
timestamp: September 01, 2017, 01:33:38 am
content: Likely a c106Y4 with a TECCOR number:http://pdf1.alldatasheet.net/datasheet-pdf/view/616880/NJSEMI/C106Y4.htmlKen

author: Gyro
author_rank: Super Contributor
timestamp: September 01, 2017, 04:59:32 pm
content: Yes, it's a T106 SCR. I've not seen one with the leafframe extended from the tab before though - More secure as they are typically just TO220 'style' package usually used vertically without a heatsink.
What is this? A transformer? - Page 1
Forum section: electronics / beginners

author: GeorgeTsak
author_rank: Contributor
timestamp: November 22, 2015, 03:49:44 pm
content: Before some time my atx power supply died so I decided to open it to take parts like capacitors, diodes and so on. However I took a part which I cannot understand what it does. It looks like a transformer but it only has two cables coming out of it. It has the metal body and a coil like a normal transformer. Any idea?

author: dmills
author_rank: Super Contributor
timestamp: November 22, 2015, 03:53:47 pm
content: Old school passive power factor correction inductor.Regards, Dan.

author: GeorgeTsak
author_rank: Contributor
timestamp: November 22, 2015, 03:57:48 pm
content: Thank you very much!

author: amyk
author_rank: Super Contributor
timestamp: November 22, 2015, 04:00:46 pm
content: Quote from: dmills on November 22, 2015, 03:53:47 pmA real one, I might add.https://www.eevblog.com/forum/chat/fake-pfc-made-of-cement/
What is this boost converter chip? - Page 1
Forum section: electronics / beginners

author: ivoras
author_rank: Contributor
timestamp: August 09, 2017, 11:36:02 am
content: Hello,I've ordered a couple of these boost converter modules from AliExpress:https://www.aliexpress.com/item/0-7-5V-to-3V-3-3V-5V-DC-DC-Boost-Converter-voltage-Step-up-Module/32800430445.htmland they've proven to be unexpectedly good as far as quiescent power consumption is concerned, so I'm trying to re-create them on my own PCB -- but I can't seem to find what that boost converter chip is.I've tried to magnify the image and read the markings; it looks something like FO2188A, but I can't seem to find any components with that model name. Any ideas what is this chip?Alternatively, can someone suggest a small, low-input-voltage (<= 0.7V), low quiescent current and cheap boost converter IC with similar characteristics?

author: Neilm
author_rank: Super Contributor
timestamp: August 09, 2017, 05:31:48 pm
content: What sort of quantities are you talking about? If you are only going for a few then that will change the suggestions. If you are happy for a few thousand then try looking at the main suppliers website - I have always found the TI site easy enough to search. A few moments gave me the TPS61099 that needs a an inductor, a couple of resistors and caps. Chip is $0.67.

author: floobydust
author_rank: Super Contributor
timestamp: August 09, 2017, 08:20:38 pm
content: From the logo it seems to be chinese semiMicrOne ME2188.PFM boost-converter. Rated 0.9-5V input, 1.8-5V output; 350kHz.I wonder about the modules 0.7V input spec.

author: floobydust
author_rank: Super Contributor
timestamp: August 09, 2017, 08:42:45 pm
content: It seems to start at 0.8V or so and run lower, depending on load.I'm not sure what the A22 vs A30 suffix is about.
What is this called (some kind of heating element) - Page 1
Forum section: electronics / beginners

author: Electron123
author_rank: Contributor
timestamp: May 26, 2025, 04:05:37 pm
content: I took apart an electric incense burner recently and found this part (see picture). I think it's the heating element. Can someone tell me how it works and what it is called?

author: Doctorandus_P
author_rank: Super Contributor
timestamp: May 26, 2025, 04:36:19 pm
content: https://html.duckduckgo.com/html?q=mica+insulated+heaterThere is simple heating resistance wire inside, and the mica plates are used for the insulation. You find this stuff in all sorts of consumer equipment. Mica is cheap and it does not need much thermal mass. (solid) Ceramic carriers for the heating wire are more robust, but because ceramic is very brittle, it must be much thicker, and this increases the thermal mass.

author: Algoma
author_rank: Frequent Contributor
timestamp: May 26, 2025, 05:03:02 pm
content: Its silver flat material held by brass rivets is a compressed sheet of Mica, the material what replaced Asbestos as a "safer" high heat thermal barrier.While a distinct mineral, there were older sources that can still contain Asbestos fibers.

author: Electron123
author_rank: Contributor
timestamp: May 26, 2025, 07:34:33 pm
content: I'd like to make something similar but about 1 inch in diameter. Is it just 2 pieces of mica sandwiching a loop of nichrome wire? The circuit from the incense burner I took apart looks pretty simple. But how do you determine what diameter of nichrome and how much to use?

author: Algoma
author_rank: Frequent Contributor
timestamp: May 26, 2025, 08:21:33 pm
content: You can salvage the such materials out of any cheap scrap toaster.Resistance, run a multimeter probe along the wire length until you get the desired (Matching?) resistance for your application. Less resistance if you want it to pass more current and produce more heat output.You can get dedicated heating elements. Nichrome stuffed in fragile mica sheet while connected to mains voltage is kinda sketchy and risky if it shorts out inside. There are better off the shelf solutions to heating elements (Ceramic heaters that embed the spicy bits inside solid material.). it depends how hot you want it all to get, and the available cooling to keep it under control without thermal runaway. There is a careful balance with heating elements, between a toasty warmer to a flaming electrocution hazard because the cat knocked it on the floor.
What is this capacitor? - Page 1
Forum section: electronics / beginners

author: mictas
author_rank: Regular Contributor
timestamp: April 28, 2015, 08:47:28 am
content: Well I have been exploring the CD4001, 4013, 4016, etc... IC's and I have been finding a number of circuits that require a 10n or 100n non polorized capacitors and wondering what are they, the Google searches I have done, all came up empty.I tried building a few already, only to have them fail.Here is a link to one project:http://startingelectronics.org/beginners/start-electronics-now/tut17-electronic-dice/I'm just planning on doing an order on eBay next chance I get.

author: Dago
author_rank: Frequent Contributor
timestamp: April 28, 2015, 09:13:30 am
content: Well a 10n or 100n non-polarized capacitor could be made by a wide variety of different technologies. In practice for general purpose stuff it will most likely be a (multi-layer) ceramic capacitor. Plastic capacitor (polypropylene etc.) used to be common previously but nowadays are used in more special applications (where for example the microphonic properties of ceramic capacitors could be a problem).

author: mictas
author_rank: Regular Contributor
timestamp: April 28, 2015, 09:20:46 am
content: Quote from: Dago on April 28, 2015, 09:13:30 amThe non-polarized capacitors, I have or I have looked up all have two letters, not just one. Is the site I am looking at not adding the 'f', as PA0PBZ is pointing out, it is just a 100nf (103) capacitor?

author: cyr
author_rank: Frequent Contributor
timestamp: April 28, 2015, 09:38:58 am
content: If you are asking if the "n" refers to the capacitance which is measured in farads, then yes. A 10n cap means a 10nF (nano farad) cap...Just like the resistors, a 2k2 resistors means a resistor with a resistance of 2200 Ohms.

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 28, 2015, 09:43:46 am
content: The pictured cap is 10nF (10 x 103=10.000pF), not 100nF which would be 104.Without a letter the capacity is almost always shown in pF.
What is this circuit? ( Running a 50kv powesupply) - Page 1
Forum section: electronics / beginners

author: Beamin
author_rank: Super Contributor
timestamp: May 10, 2019, 11:11:44 pm
content: It has 4 FETs and "an integrated circuit" as he calls it generating 1000Hz. He says "generates both sides" Does he mean those FETs are in a push pull amplifier configuration?Does the noise come from the primary vibrating against the field made by the iron core; ie would it not make that noise if there was no magnetism from the iron core?https://youtu.be/uCm1iPLVe8I?t=2050This guy is the creepiest, but also the most genius guy on youtube. I remember the first time I saw a video where you saw more then just his hands. Wasn't expecting that!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 11, 2019, 07:58:33 am
content: Creepiest? I forget if "he" or "her" is appropriate, but they're somewhere on the spectrum; I'd think you'd have identified with them more.Cool projects in any case!Yes, push-pull, specificallyH-bridgeso both sides are fully driven.Noise may be the core, yes (magnetostriction). At these voltages, it may be insulation moving around as well. Not so likely wires moving, as that takes a fair amount of current.Tim

author: Zero999
author_rank: Super Contributor
timestamp: May 11, 2019, 12:08:05 pm
content: He talks about the oil shorting out the primary and secondaries but the oil should be a dielectric, capable of withstanding a high voltage, so shouldn't short out anything.I stopped watching after that point because it didn't make sense.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 11, 2019, 08:44:15 pm
content: One of the few electronics related channels I watch. He does some pretty interesting stuff.QuoteYes. Towards the end he shows you the schematic.

author: ArthurDent
author_rank: Super Contributor
timestamp: May 11, 2019, 11:46:40 pm
content: That video is just wrong and dangerous in so many ways. For one, using the torch to cut that tank with the uncapped cans of paint thinner right next to the flames. This guy should be a front runner for the Darwin awards.
What is this circuit for? - Page 1
Forum section: electronics / beginners

author: vmallet
author_rank: Regular Contributor
timestamp: July 30, 2020, 10:59:06 pm
content: I am trying to figure out the circuit of a smart wifi socket and I bumped into a part of the circuit that makes no sense to me.The overall device is pretty straightforward with an ESP8266 controlling the relay/LED/etc. Here's the strange bit:GP2 goes to the GPIO2 pin of the 8266.What does this do? My current thinking is that Q1/R28/R29 might as well not be on the PCB because they do nothing but maybe I'm missing something, hence the question.Thanks!

author: Whales
author_rank: Super Contributor
timestamp: July 30, 2020, 11:05:26 pm
content: ~30mV base bias? Indeed that circuit doesn't do anything other than pullup GP2 by 10K.Could there be inputs to this circuit you are missing? Traces under parts or in hidden layers of the PCB? If that 1.5K resistor goes to a signal rather than GND then this would be a functioning inverter.

author: langwadt
author_rank: Super Contributor
timestamp: July 30, 2020, 11:13:45 pm
content: Quote from: vmallet on July 30, 2020, 10:59:06 pmsure the 100k is connected to 3.3V ?

author: vmallet
author_rank: Regular Contributor
timestamp: July 30, 2020, 11:19:03 pm
content: Quote from: Whales on July 30, 2020, 11:05:26 pmThat's what I thought too and I checked it over three times, but I don't see anything coming to the gate..Here's the PCB section (you can click for full size):The via in the emitter pad goes straight to GND on the other side.The trace out of R29 goes straight to 3V3.The trace out of the collector goes to GP2 and the 10K pullup.Maybe they had something there in the past, ditched it, and kept the left-overs?

author: vmallet
author_rank: Regular Contributor
timestamp: July 30, 2020, 11:47:24 pm
content: Quote from: langwadt on July 30, 2020, 11:13:45 pmPretty sure at this point. I see it visually, and I just re-measured a 0 Ohm continuity between R29 and the output pin of the 3.3V regulator. Very bizarre.
What is this component? - Page 1
Forum section: electronics / beginners

author: Alfgan
author_rank: Contributor
timestamp: February 02, 2020, 09:28:01 pm
content: Hello everyone,I found a box of components from where I was a kid. I am with my friend used to collect random electronic components and then trade them. Recently I too that box to see what components I had and found this component which I do not know that it is. Maybe you could tell me? Is it a some quartz or capacitor?Thank you.Best wishes

author: ataradov
author_rank: Super Contributor
timestamp: February 02, 2020, 09:46:53 pm
content: The picture is blurry, but it looks like a ferrite bead.

author: Alfgan
author_rank: Contributor
timestamp: February 02, 2020, 10:09:17 pm
content: oh, thanks

author: pcmad
author_rank: Regular Contributor
timestamp: February 03, 2020, 03:42:51 am
content: if solid and 2 pins it could be miylar cap if hollow and i cylinder then ferrite bead

author: Shock
author_rank: Super Contributor
timestamp: February 03, 2020, 04:03:27 pm
content: It's a radial style ferrite bead (with no legs).
What is this component ? - Page 1
Forum section: electronics / beginners

author: ArereDin
author_rank: Newbie
timestamp: October 06, 2023, 06:59:16 am
content: I have to build a Lifi emmiter/receiver for a school project, i already have a picture of what the final result should look like and i don't recognize one of the components.I'm pretty sure the component is part of the receiver part.The light we receive shines on a photodiode, the signal is then amplified and fed into an arduino uno that converts the signal to bits.Here is the component (red arrow pointing to it)

author: calmtron
author_rank: Regular Contributor
timestamp: October 06, 2023, 07:06:39 am
content: Polymer film capacitor.
What is this component ? - Page 1
Forum section: electronics / beginners

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: March 22, 2015, 01:52:00 pm
content: Thanks !

author: dmills
author_rank: Super Contributor
timestamp: March 22, 2015, 02:10:17 pm
content: Gas discharge tube, if the voltage becomes excessive the thing arcs and diverts the energy away from whatever it is protecting.They are available in voltages from ~60 to well over a 1,000v breakdown. and while not as fast as a MOV they can handle a great deal of energy.Regards, Dan.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: March 22, 2015, 02:21:50 pm
content: Thanks Dan,Is it for the same use that are sometimes neon bulbs in circuits ?As in this PM3209 oscilloscope ?

author: N2IXK
author_rank: Frequent Contributor
timestamp: March 22, 2015, 02:29:48 pm
content: In some cases, yes. But neon lamps can also be used in other applications such as voltage regulation, relaxation oscillators, etc.GDTs like you show are only used for transient voltage suppression.

author: SeanB
author_rank: Super Contributor
timestamp: March 22, 2015, 05:49:22 pm
content: Yers, the neon lamp can be used as a voltage clamp, with it having low capacitance, but the voltage will be somewhere between 80 and 130V (depends on the individual lamp, whether it is lit and it's age and use) and will have limited current and power handling. The gas discharge tube can handle very high peak currents and has very low on state voltage with a reasonably defined turn on voltage.The one you show the picture of has a deposit of Americium sputtered on the glass wall on the inside so as to make the turn on voltage well defined, even in the dark and with a slow rise. It provides a small amount of ionisation current to help start the arc discharge instead of having a glow discharge. When triggered it has a very low voltage drop, even at high current, though the energy it can handle is limited, but it will typically survive a close lightning strike, unlike the neon lamp.