hybridfree/eevblog-posts huggingface dataset:
Rubber cover on capacitor - Page 1
Forum section: electronics / beginners

author: TNb
author_rank: Regular Contributor
timestamp: January 19, 2015, 11:02:04 pm
content: Does anybody know what is the purpose of the rubber cover that is found sometimes on capacitors in power supplies? I guess it is some kind of explosion protection, but it's just a guess, can't find any info on internet.

author: sleemanj
author_rank: Super Contributor
timestamp: January 19, 2015, 11:11:29 pm
content: I'd assume it's just to prevent stuff shorting accidentally to the case (ie if it's next to a live heatsink).

author: Richard Crowley
author_rank: Super Contributor
timestamp: January 19, 2015, 11:40:09 pm
content: Heat shrink tubing isn't going to give you much protection from an explosion.Looks like simply some extra insulation around the can.Without the context (where it sits on the board) hard to tell WHY they would do that?I've actually never seen an after-market piece of heat-shrink tubing over a radial electrolytic cap like that.

author: free_electron
author_rank: Super Contributor
timestamp: January 20, 2015, 12:21:41 am
content: creepage for the high voltage. the can of the capacitor has essentially the rectified mains on it. there is a requirement for creepage , clearance and 'fingerpoking'.the standard isolation plastic around a cap may not hold during the hipot testing.shoving some heatshrink tubing over that solves that problem.

author: Seekonk
author_rank: Super Contributor
timestamp: January 20, 2015, 03:30:08 pm
content: To make it clearer, "creepage for the high voltage." means that UL deemed insufficient separation or possible contact with another live part and that the capacitor's printed shrink had no insulation rating.

author: coppice
author_rank: Super Contributor
timestamp: January 20, 2015, 03:35:36 pm
content: Quote from: Richard Crowley on January 19, 2015, 11:40:09 pmYou'd be surprised. You sometimes find heat shrink over the MOVs at power inlets. Overstressed MOVs can explode and rip through thick casings. However, if you just restrain the pieces a little as the blast occurs it dampens the fragments considerably, and the equipment case is unlikely to be breached.

author: Stonent
author_rank: Super Contributor
timestamp: January 21, 2015, 09:40:09 am
content: Capxon inside!
Rubber Dome Switches - Page 1
Forum section: electronics / beginners

author: JakeCharman
author_rank: Newbie
timestamp: October 19, 2016, 06:29:07 pm
content: Hi,I'm trying to connect to a musical keyboard which uses a series of rubber dome buttons connected in a scan matrix. However, I can't get any output from my multimeter when I connect it across the pins. I already know how the scan matrix is wired thanks to a schematic but I'd like to learn how to test these switches anyway.At first, I thought there may not be enough power present for these switches to work however I checked the multimeter I'm using on my other one and it's putting out around 3v in diode check mode and I can pull about 1.6mA from it, the circuit board in the keyboard however is only providing around 0.4v. One thing to note is that there are a series of diodes on the board, the diode check does not beep in either polarity when connected directly across these diodes but I can't tell if there is some sort of insulation over the solder joints.The keyboard is fully working so dead components aren't an issue.I'd appreciate any insights into what I might be doing wrong.Jake

author: amyk
author_rank: Super Contributor
timestamp: October 20, 2016, 12:55:47 am
content: What range are you using exactly with your multimeter? It sounds like the switches and traces within the keyboard may be printed with carbon conductive paint, which tends to be extremely high resistance even when closed. (But a typical CMOS input only needs a few uA of current, so the resistance is no problem.)

author: Towz
author_rank: Contributor
timestamp: October 20, 2016, 03:33:56 am
content: Test for resistance, membrane keypads/matrices are ususally carbon printed and its resistance can get from 100s to 1000s ohms
Rubidium Frequency Standard... do I need it? - Page 1
Forum section: electronics / beginners

author: mortos360
author_rank: Regular Contributor
timestamp: July 12, 2012, 09:41:23 am
content: I am about to buy the Rigol DG4000 series waveform generator, and I wonder if I should get 1 of the rubidium FS from eBay.If I got this right, the frequency standard should increase the accuracy of the waveform generator but leave the same resolution, is that right?And if it does increase the accuracy, will it make any difference for me? (its a 70MHz generator which I plan to use to generate and measure only a few Hz maybe KHz)

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 12, 2012, 10:35:55 am
content: The DG4062 has very good accuracy to start with. Unless you have a particular need for high accuracy it is more than adequate.The frequencies you are using are irrelevant - 1ppm is 1ppm regardless of frequency, although a generator may introduce other errors at some frequencies depending on its architecture

author: mortos360
author_rank: Regular Contributor
timestamp: July 12, 2012, 10:51:08 am
content: MikeThanks for the answer!
Rui Deng  DP 5015  DP 50V15A programmable power supply - Page 1
Forum section: electronics / beginners

author: hary
author_rank: Contributor
timestamp: February 28, 2019, 08:31:13 pm
content: HI.I was considering to buy a Rui Deng DP 5015 / DP 50V15Ahttps://fr.aliexpress.com/store/product/RD-DPS5020-Constant-Voltage-current-Step-down-communication-digital-Power-Supply-buck-Voltage-converter-LCD-voltmeter/923042_32821185351.html?spm=a2g0w.12010612.8148356.1.78933931XSezfeor DPS8005 programmable power supply but have no DC PSU supply for it. So I would need to buy one.For my previous DPS3005 (30V, 5A) I use an old 20V laptop supply witch was free, but for the one I'm considering now, I don't know where to find a proper PSU supply.What do you use ?I've seen somehttps://www.ebay.fr/itm/500W-72V-6-9A-220V-INPUT-Single-Output-Switching-power-supply/222240260342?hash=item33be8d40f6:g:5WAAAOSwknJXzPsnorhttps://www.ebay.fr/itm/500W-60V-8-3A-220V-INPUT-Single-Output-Switching-power-supply/222241238393?hash=item33be9c2d79:g:b9IAAOSwknJXzlmEBut they're are getting quit expensive and don't fit exactly the needs (only 6.9A when the DPS5020 witch needs at least 20A !)What do you use on your side ? Or what advice would you have ?These little DPS programmable bench supply are very practical .

author: metrologist
author_rank: Super Contributor
timestamp: February 28, 2019, 10:35:16 pm
content: With the 5015, the most practical is probably a 48V switch supply. I just had one in 36V and use it fine. I plan to use also a 36V Li-ion pack for portable operation.

author: bloodhunter007
author_rank: Newbie
timestamp: July 30, 2019, 05:57:04 am
content: Quote from: hary on February 28, 2019, 08:31:13 pmFor DPS5020, you can use that 60V power supply, but that current is too small, you can search a more big current switch power supply, it should be okin fact, you can search a 60V/20A switch power supply, it should be ok ... but when you use , please lower than 60V to use , it will be safe

author: bloodhunter007
author_rank: Newbie
timestamp: July 30, 2019, 05:58:08 am
content: Quote from: metrologist on February 28, 2019, 10:35:16 pmin fact, it depends on your need, only input voltage is on the range, it will be ok
Run capacitors: why electrolytic can not be used - Page 1
Forum section: electronics / beginners

author: sdancer75
author_rank: Frequent Contributor
timestamp: November 11, 2019, 03:11:33 pm
content: From wiki : Run capacitors are designed for continuous duty while the motor is powered, which is why electrolytic capacitors are avoided, and low-loss polymer capacitors are used.I am still don't understand, why electrolytic must be avoided....It's because they last less before they fail or there are also other restrictions?Regards

author: RoGeorge
author_rank: Super Contributor
timestamp: November 11, 2019, 03:18:44 pm
content: Motors are usually driven by AC, which means the polarity of the wires alternates between +/- then -/+ on the same pair of wires.Electrolytic capacitors are usually polarized capacitors, they does not support reverse voltage.

author: sdancer75
author_rank: Frequent Contributor
timestamp: November 11, 2019, 03:21:28 pm
content: Yes, didn't though of that, so I missed it at allBut how about non polarized electrolytic capacitors like start capacitors? Does this will work?

author: AVGresponding
author_rank: Super Contributor
timestamp: November 11, 2019, 03:31:40 pm
content: Not quite sure why you think electros aren't used for this, they certainly are. They are simply a non-polarised type.It's not as common as it used to be though, these days inverters are so cheap, most industrial motors use them, and most of those inverters have integrated filters, but some don't.Depending on the size and ratings, you might still find them there.

author: Gyro
author_rank: Super Contributor
timestamp: November 12, 2019, 10:21:36 am
content: Quote from: RoGeorge on November 11, 2019, 03:18:44 pmQuote from: sdancer75 on November 11, 2019, 03:21:28 pmMotor START capacitors are bipolar (non-polarized) electrolytics as they are typically too high in value to comfortably use film capacitors (cheaper too for the same value). They have high loss however, which would shorten their life and make them overheat in continuous use - they are designed for minimum case size possible for practical reasons.Motor RUN capacitors are (normally Polypropylene) Film types because their losses are much lower, allowing them to run continuously at low temperature and achieve maximum life and motor efficiency. Motor run capacitor values are significantly lower than start ones, making the film ones practical at a sensible case size.P.S. Hopefully obvious, but the motor Start capacitor is taken out of circuit by a centrifugal switch as soon as the motor reaches operating speed. Normally a couple of seconds max.
Run mcu from high voltage range - Page 1
Forum section: electronics / beginners

author: NeedCoffee
author_rank: Newbie
timestamp: March 05, 2024, 03:43:42 pm
content: Hi,I would like to be able to run an mcu from 0.8v to 20v input voltage. I am wondering what the best way to do this is. I have looked at using an LDO before a boost regulator. So for example a 3v ldo then a boost regulator like the mcp1640 to step up the voltage to the mcu minimum. I am unsure of what ldo's will work at such low voltages. The mcu will need about 20ma current at 3.3v. Is there a better way to clamp the input voltage to the mcp1640? Ideally i am looking for a output voltage that will stay the same as VIN until VIN hits 3.0v then be clamped at that voltage. Any suggestions on parts or regulators that can accept up to 20v input but can still pass voltage at 1v?Thanks

author: mariush
author_rank: Super Contributor
timestamp: March 05, 2024, 04:16:44 pm
content: The 3v ldo won't work with a voltage lower than 3v, exactly how low depends on what voltage reference it uses and other factors. With less than 3v + dropout voltage, the output of the 3v ldo will be more or less input voltage - dropout voltageYour best option is a buck-boost regulator, but such buck-boost regulators that accept high voltages (like more than 6v) typically need higher minimum voltagesfor example TPS62175 does 4.75 - 28v in, output up to 6v and 500mAChips like TPIC74100 or TPS55065 will work from 1.5vhttps://www.digikey.com/en/products/detail/texas-instruments/TPIC74100QPWPRQ1/1531097https://www.digikey.com/en/products/detail/texas-instruments/TPS55065QPWPRQ1/2092500and if you look hard you'll find other chips ... here's a starting point :https://www.digikey.com/short/vbzp9tz9

author: radiolistener
author_rank: Super Contributor
timestamp: March 05, 2024, 05:10:41 pm
content: if your input voltage is AC, you can use step-up transformer to transform 0.8V to something like 6-7V and then use rectifier and voltage regulator to get 3.3V or 5VIf voltage is DC, you can use one step-up DC/DC and one step-down DC/DC and switch them depends on input voltage.

author: NeedCoffee
author_rank: Newbie
timestamp: March 05, 2024, 08:45:34 pm
content: Thanks for the replies !, The tpic74100 looks interesting but slightly over the threshold i need. The mcp1640 will work at to boost the voltage nicely from 0.8v to 3.3v. Is there a simple way to limit or clamp this the voltage at 3v supplying the 1640 ? It does not have to be precise.I guess an LDO or buck-boost mentioned is the closest thing to a "clamp" circuit. Is there a way that I can switch from direct supply if below 1.5v for example and when the threshold is reached switch the input to the mcp1640 over to regulated output of the tpic74100?
Running a 220V pump off of two 120V outlets? - Page 1
Forum section: electronics / beginners

author: JMinSC
author_rank: Newbie
timestamp: February 24, 2018, 09:25:19 pm
content: My well has a 220V submersed pump. I'm looking for a generator to run the pump should I ever lose power. I'm not going to need continuous power, I'll just run the pump long enough to fill my containers (about 100 gallons), then shut down the generator.My questions concern the generator. Can I use a generator with two 120V outlets to run the 240V pump?I'm thinking I can rig up a "patch cord" to plug into the two 120V outlets on the generator and have a single connection to hook up to the 240V input to the pump. The 240V is just two 120 hot leads, and a single neutral lead, right? So, can I use the two hot connections from the two 120V hot outputs from the generator, and make the two neutral outputs from the generator connected together, and run my well pump off of that?

author: drussell
author_rank: Super Contributor
timestamp: February 24, 2018, 09:26:58 pm
content: You need a generator that generates 240 volts, to start....Or a pump which can be wired for 120 volts.

author: mtdoc
author_rank: Super Contributor
timestamp: February 24, 2018, 09:30:04 pm
content: No.Read up on split-phase power systems. Emphasis onphase.

author: JMinSC
author_rank: Newbie
timestamp: February 24, 2018, 09:32:24 pm
content: That answered my question.Thank you!
Running a laptop off solar - Page 1
Forum section: electronics / beginners

author: paulca
author_rank: Super Contributor
timestamp: May 23, 2018, 02:40:12 pm
content: So now it's summer my tiny solar panel setup is producing more power than I can use from my USB powered devices and a bunch of other stuff.I need to add more load. It's pointless to consider an inverter as I only have 38Ah of battery and a 10A limit.I use the laptop to watch YouTube a few hours a day, so I figured it looks like a good candidate for powering off solar.This leaves me a number of options.1. Use a "Car laptop charger"2. Use a generic 5A boost converter that will output the 19V required.One concern is knowing how much power the laptop actually draws, so as an experiment I will see about powering it off a bench supply while I find a better solution. The car charger gizmos seem to state 80W on a few, at 19V that's about 4A which sounds about right. Of course it will pull about 6A on the 12V side, which is also fine. I can either use a LiPo that goes with the Laptop or I can charge the laptop at the charge controller and run it off batteries elsewhere.Anyone have any suggestions or gotcha's?

author: The Soulman
author_rank: Super Contributor
timestamp: May 23, 2018, 02:53:05 pm
content: I'd say "car laptop charger" less hassle and the least chance of destroying your laptop.Note that "professional" laptops such from hp and dell actually has a third connection from charger to laptop that sends some identification data,without valid data the laptop may not charge and throttle down the cpu.

author: Cyberdragon
author_rank: Super Contributor
timestamp: May 23, 2018, 06:32:42 pm
content: Quote from: The Soulman on May 23, 2018, 02:53:05 pmIf they're like Apple chargers, then the charger info chip will be in the plug head. You'd have to cut the cord off one and see how many wires go to the actual power converter. If there is only two, then you can just use the connector from a real charger. However, note that it will think it's the original charger so you have to make sure it can supply that current otherwise it will overload and make the PC throw errors.Some laptops will also autodetect like phones do where it increases the current until the supply shuts off then sets the limit right below. This still has to be at least the minimum charging current.

author: paulca
author_rank: Super Contributor
timestamp: June 01, 2018, 12:40:16 pm
content: I went with a 90W car laptop charger off ebay. I already had a cigarette lighter socket with an XT60 soldered to it, so I can run the laptop off a LiPo charged from solar, or the charge controller itself which has an XT60 on it's load output.Interestingly it took two evenings watching youtube etc. to bring the 5 Ah Lipo down to 10.6V, So I could get almost 5 hours out of it. That suggests the laptop is only pulling an average of 1 Amp / 12 Watts. I would have expected many times more than that.
Running Hovermotor from VFD - Page 1
Forum section: electronics / beginners

author: made2hack
author_rank: Frequent Contributor
timestamp: January 10, 2019, 10:29:27 am
content: Hello all,Can I drive a hovermotor from a VFD intended for induction motors? Or do I need to get a hobby ESC? I mean I know the hovermotor is a so-called brushless DC, but it is still wired as 3 phase motor. Would the VFD work? Or do I risk killing the motor?Thanks,

author: capt bullshot
author_rank: Super Contributor
timestamp: January 10, 2019, 10:44:00 am
content: Short answer: no.Long answer: The DC brushless requires some kind of position feedback to the driver - can be sensorless. A typical VFD for induction motors doesn't have position feedback, just outputs a ramping up and down frequency with the amplitude (voltage) proportional to the frequency (U/F mode).If one fiddles with these settings (ramp speed, full speed voltage/frequency and voltage raising with frequency) it might be achieveable to get the motor running - but it won't be reliable. E.g. at a different mechanical load, the ramp speed won't match the different needs of the motor then, the motor will loose sync to the frequency and cease to create torque (in German this is called "kippen", don't know the English term) and stall in turn. Typically this causes the VFD to stop due to overcurrent, but if the VFD isn't matched to the motor size, it'll continue to push power into the stalled motor which will cause the motor to burn.So you'd better use a dedicated BL DC motor controller.

author: beanflying
author_rank: Super Contributor
timestamp: January 10, 2019, 10:46:16 am
content: EDIT SNAP to capt bullshotShort answer is NO. Were you hoping to use AC power to drive the motor? And for what retasking purpose?Most of the hoverboard motors I have seen also use Hall effect sensors as part of the control loop? The reason they tend to get used on Wheeled R/C or hoverboards is you can get better torque from the drive.Depending on how they are wired you should be able to use a Non Sensored BDLC ESC by simply not using the Hall Sensors. Or you may (no guarantee) be able to get a R/C Car sensored controller to work with the motor too.

author: made2hack
author_rank: Frequent Contributor
timestamp: January 12, 2019, 11:29:56 am
content: Thanks,I did not want to use a VFD, I just wanted to power on the hovermotor until I get an ESC to come in.
Running raspberry on laptop screen - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: June 23, 2015, 03:15:49 pm
content: 1. I have RPI2, model B with raspbian loaded on it.2. TO see the GUI, you have to connect a seprate monitor to RPI2 board.3. Is there anyway so that data can be viewed on laptop screen.because usually we carry laptop rather than monitor.4. One way is to get data out on uart terminal. But that is entirely terminal based.5. Also I have reading this:https://pihw.wordpress.com/guides/direct-network-connection/I am through all steps & can ping the laptop also. Able to set up connection by putty also.I am stuck in last step titled "Using X11 and Xming"Nothing happens when I run Xming, no screen opens.

author: BradC
author_rank: Super Contributor
timestamp: June 23, 2015, 03:21:37 pm
content: x11vnc and a vnc client on the laptop.

author: lapm
author_rank: Frequent Contributor
timestamp: June 23, 2015, 03:22:28 pm
content: If you can use static ip-adresses and can network raspi and laptop, you could always use VNC or one of its variants...

author: Bob F.
author_rank: Regular Contributor
timestamp: June 23, 2015, 08:48:16 pm
content: https://www.raspberrypi.org/documentation/remote-access/vnc/IIRC, I also had to google around a bit to give the raspi a fixed IP address on my network but once setup, it works like a dream. Likewise, you can use Putty on your laptop to connect to the raspi command shell using ssh.Good luck, Bob.
Running tacks in gound plain layer - Page 1
Forum section: electronics / beginners

author: Ray Hall
author_rank: Newbie
timestamp: June 11, 2018, 09:47:04 pm
content: Hello,I am making a PCB for testing automotive electronic controllers. The PCB is four layer (Top, GND, Power,Bottom). I need to run sixteen more tracks and cannot find the room to do this on the top or bottom layers. I am thinking of running them on the ground plain layer. The signals are 0 to 5 volt and 0 to 14 volts.Is this okay to do, or should I run them in the power plain ?Ray.

author: BocaDev
author_rank: Contributor
timestamp: June 11, 2018, 10:04:04 pm
content: If I were you, I would never touch the ground plane. Take the power plane and run a split plane with power in one and signals you need to connect in the other.

author: Aspin
author_rank: Newbie
timestamp: June 12, 2018, 02:35:49 am
content: Quote from: BocaDev on June 11, 2018, 10:04:04 pmYes this is What I would Advise.Noting which ever plane you Choose try to keep it to a minimum and be aware or return/supply current paths and do not cut them with these traces.

author: Ray Hall
author_rank: Newbie
timestamp: June 12, 2018, 04:15:32 am
content: Thank you for your replies. I will split the power plane and keep it way from vital power supply areas.Ray.

author: ejeffrey
author_rank: Super Contributor
timestamp: June 12, 2018, 05:29:22 am
content: Keep in mind that at AC, ground and power planes are equivalent. If you have any high speed signals on the bottom their return current will travel in the "power" plane, not the "ground" plane. If those signals pass over a cut in the power plane, they will see a large inductance due to the return path disruption. This will cause stray coupling, noise, and signal reflections.The normal reason to split power planes is because you have multiple supplies. If one region of your PCB is running on 3.3 V and another on 2.5 V, you would divide the power plane and try to avoid having any signals run over the gap. Since you are doing this because you are running out of routing space, chances are you will have signals crossing the gap. Try to keep that to low-speed, non critical signals and add supply stitching capacitors across the gap to allow a path for return currents.
Russian Capacitor Tolerance Code - Page 1
Forum section: electronics / beginners

author: rstor22
author_rank: Regular Contributor
timestamp: July 15, 2016, 09:09:40 pm
content: On eBay some sellers have high tolerance Russian capacitors with the tolerance indicated as 0.5% on the capacitor itself, for example:http://www.ebay.com/itm/8000pF-350V-0-5-ex-USSR-Silver-Mica-SGM-Capacitor-Hi-End-16pcs-/252013310113?hash=item3aad29f0a1:g:2hAAAOSw~gRVk7~DI see some listings which advertise 0.5% however on the capacitor itself it is marked as +/-5n0 (crossed out zero)http://www.ebay.com/itm/1000pF-350-V-PRECIZE-0-5-LOT-OF-2-RUSSIAN-SILVER-MICA-CAPACITORS-SGMZ-A-/272294625257?hash=item3f66063fe9:g:NPQAAOxyni9TDHRyIs the second link also 0.5% tolerance as advertised? The reason I ask is that I purchased one from each seller. The 8000pF measures 7990pF, however the 1000pF reads 1030pF so I am wondering if the 1000pF is really 0.5% tolerance.Thank you

author: wraper
author_rank: Unknown
timestamp: July 15, 2016, 09:35:32 pm
content: 8nF one clearly state +/-0,5%, second is 1000pF +/- 5pF which is the same as 0.5%, there is no "n" letter, it is Cyrillic "p"https://en.wikipedia.org/wiki/Pe_(Cyrillic).What you are using for measuring capacitance? if multimeter, no way you can expect 0.5% accuracy, especially without zeroing measurement without cap attached.

author: rstor22
author_rank: Regular Contributor
timestamp: July 16, 2016, 03:51:04 am
content: Yes. I didn't follow the zeroing procedure of the instrument which mentions to keep the cable away from AC powered devices. It now reads between 1010-1020 pF.
Russian Capacitor Voltage confirmation - Page 1
Forum section: electronics / beginners

author: Jwillis
author_rank: Super Contributor
timestamp: June 16, 2020, 09:41:04 pm
content: This .0047uF is 400V ? I must be googling wrong because I can't find it.

author: Gyro
author_rank: Super Contributor
timestamp: June 16, 2020, 09:56:06 pm
content: Yes, you've got it. 'B' is the Cyrillic version of 'V'. It's a 400V DC rating.Edit: You've got too many zeros, it's 0.047uF.

author: Vovk_Z
author_rank: Super Contributor
timestamp: June 16, 2020, 11:03:38 pm
content: Yes, "1 Вольт" (ru) = "1 Volt" (en).All K73-xx is PET/Lavsan type. K73-15 is a polyester film foil capacitor.An attachment (with an English language, that is very rare) is for K73-15M type (not K73-15B), but I think it has to be about the same (just modern one).I google-find thatdatasheet here.

author: Jwillis
author_rank: Super Contributor
timestamp: June 17, 2020, 12:32:19 am
content: Thanks folks. Learned something new again. I'm surprised that a 63V (now I know it's 63V) cap didn't explode with 200V . Good thing I took that out because it wasn't needed.

author: Vovk_Z
author_rank: Super Contributor
timestamp: June 17, 2020, 05:49:00 pm
content: Quote from: Jwillis on June 17, 2020, 12:32:19 amFilm or ceramic type - yes, they withstand several times overvoltage typically (short time and unsafe).

author: Jwillis
author_rank: Super Contributor
timestamp: June 17, 2020, 06:26:25 pm
content: This electrolytic . I have to be more careful .

author: Vovk_Z
author_rank: Super Contributor
timestamp: June 17, 2020, 08:12:44 pm
content: K50-24 - yes. " K50 " code means electrolytic type. That special K50-24 is very reliable type. It was wide used in military. I'm not sure if have seen a broken one.

author: Jwillis
author_rank: Super Contributor
timestamp: June 18, 2020, 03:01:03 am
content: Yes K50-24 470MK Φ ± 80 over 20 % 63B (470uF 63V) . Test measurement gives 411uF @1kHz with Φ -87oESR 0.02Ω .Which is as good if not better than many others. I'm impressed.

author: Vovk_Z
author_rank: Super Contributor
timestamp: June 19, 2020, 05:52:06 am
content: I have the exact experince with K50-24 ESR measurements. They very often have about the same (or even a bit lower) ESR as modern Low-ESR one types. And they usually don't show a need to be replaced after 40-45 years.
rusting diodes on your pcb - Page 1
Forum section: electronics / beginners

author: robowaffe
author_rank: Regular Contributor
timestamp: July 19, 2023, 05:43:39 pm
content: you reckon if you get a pcb from pcb way you can put a vinegar mask on it, and rust diodes on it, to get copper hydroxide diodes, but u have to press two boards together to get the anode and the kathode to connect.

author: Gyro
author_rank: Super Contributor
timestamp: July 19, 2023, 07:20:51 pm
content: Don't feed the trolls!

author: Zero999
author_rank: Super Contributor
timestamp: July 19, 2023, 07:46:52 pm
content: Why?
RX V1700 Yamaha Receiver - transistor short (with diagram!) - Page 1
Forum section: electronics / beginners

author: chode
author_rank: Newbie
timestamp: August 18, 2016, 08:01:49 am
content: Hey all!I have a Yamaha RX-V1700 Receiver that was auto-powering off due to abnormal DC Voltage.I ventured into the unknown using the repair manual and have finally discovered the problem in the Main board. This is the manualhttp://elektrotanya.com/?q=showresult&what=rx-v1700&kategoria=&kat2=schematicsI found +46 volts at the surround sound L output post at the back and followed this back through to the main amplifier board. I found a short on two pins of transistor Q370 (see attached). I have now removed both the Q370 transistor (2S C5291) and the C321 capacitor (100pF 630V) and the amp is again working perfectly.As its working, can anyone tell me what these two parts actually do? I'm not sure if I should bother ordering replacements and soldering these in?Thanks!

author: fubar.gr
author_rank: Unknown
timestamp: August 18, 2016, 11:12:31 am
content: This looks like a push-pull arrangement (actually several stages of push-pull connected in series), where Q370 "pulls" and Q371 "pushes" (or is it the other way around?)With Q370 removed, it "pushes" like before, but it only "pulls" weakly.It is still going to work but with some distortion and non-linearity, so the audio quality won't be the same.

author: cvanc
author_rank: Frequent Contributor
timestamp: August 18, 2016, 11:29:36 am
content: What fubar said.It may work now but you have lost the symmetry of a push-pull circuit relationship. Distortion (and maybe headroom) must be compromised. Definitely replace the parts.

author: chode
author_rank: Newbie
timestamp: August 18, 2016, 11:56:15 am
content: This is great, thank you both.I assumed it was just additional signal amplification as it seemed to play ok through the speaker. I'll get the parts ordered.

author: chode
author_rank: Newbie
timestamp: August 18, 2016, 12:02:28 pm
content: Also - my guess then is that Q370 "pushes" more voltage when it gets a signal at the base as its on the +ve branch of the amp with an npn transistor.That would suggest Q371 "pulls" more voltage across to the -ve branch when it gets a signal at the base of the pnp transistor?I could be massively wrong - I'm a complete novice at this!

author: macboy
author_rank: Super Contributor
timestamp: August 18, 2016, 04:03:37 pm
content: The transistor is labelled "C5291", but this is short form for "2SC5291". The initial "2S" is sometimes implied, it refers to the device having 2 junctions (transistors).
Ryobi 24V Lithium battery shows weird voltage - Page 1
Forum section: electronics / beginners

author: R-star
author_rank: Newbie
timestamp: July 24, 2023, 12:11:00 am
content: Hello, guys,I have been given this Ryobi 24V Lithium battery, but it shows weird voltages. I hope someone can clarify why.The battery has 3 terminals, marked Positive, Negative and T2, which, I assume is the NTC sensor lead. In this order:POS, T2, NEG. (see pic 1)I am measuring the voltage. I am getting:POS----T2 = 21.1 V (picture 2)POS----NEG = 6.26 V (picture 3)T2----NEG = 0 V (picture 4)Hmmm... Should it not be 20 something volts between the POS and the NEG terminals?Why is the T2 relative to the POS higher potential than the NEG terminal?The last two pictures are just the battery label, and the type.Yes, the screws are missing from the battery, because I have removed them wanting to take a look at how everything is connected inside, but it is not opening, possibly I will need to remove a label or maybe damage the edge with flat screwdrivers...

author: electr_peter
author_rank: Unknown
timestamp: August 28, 2023, 08:12:20 pm
content: Hi,Ryobi batteries may contain control module:QuoteThis seems to be the case this battery. DMM does not show raw voltages of cells (like for regular dumb batteries), but some weird interaction result with communication and protection module.Can you charge it and test it with Ryobi tools? Other than that you can carefully disassembling and checking cell voltages. Using it as is for non Ryobi tools may be tricky.
ryobi battery  - Page 1
Forum section: electronics / beginners

author: Meguinness
author_rank: Newbie
timestamp: June 30, 2025, 05:28:05 pm
content: Hi guys I need some help...I have this Ryobi battery that completely went flat....I managed to slowly recharge the cells and bring them back to 4v....I then started noticing the area marked in red becoming extremely burning to the touch ...R2 in particular ....so I disconnected the tabs on the side next to it . I had a good cleaning with electric contact cleaner but once connected the cell back same problem. This is surely why the battery went dead the first time. Any beginner tips to locate the problem? I am ready with a multimeter..what should I check.i have already replaced R2 and U1 and C1 as i believed they were shorted but no luck . i have disconnected the batteries completly . i noticed that while applying 19v to the pcb terminals the voltage output from the top connectors the one that goes in to the tool goes down from 19v while the area circled got burning hot. the battery leds level not workin at all.thanx
s Band load - Page 1
Forum section: electronics / beginners

author: kiss1970
author_rank: Newbie
timestamp: December 31, 2014, 08:24:26 am
content: Hi, i just found in my work one S BAND load (this is i found out by searching the internet) . The company who made this is EEV nd the type written on it is : B7LD98401Can anyone please tell me some of it's characteristics? e.g. power, resistance, etc ?

author: richard.cs
author_rank: Super Contributor
timestamp: December 31, 2014, 10:58:33 am
content: If that's EEV as in "the English electric valve company" then they still exist under the name "E2V", you could ask them.

author: mhzghz
author_rank: Contributor
timestamp: January 05, 2015, 07:38:34 am
content: It's a 50 ohm load for a RF isolator in a marine radar unit. It'll work over a large frequency range.

author: steve_w
author_rank: Regular Contributor
timestamp: January 06, 2015, 05:22:02 am
content: S Band is around 2.7 GHz used in marine and ATC radar.regardsSteve W

author: katzohki
author_rank: Frequent Contributor
timestamp: January 06, 2015, 05:50:15 pm
content: Look up "dummy load" to get an idea what this is used for. 50 ohms is pretty much a given. I wish I could tell you what the rating is, but it looks to me that it should handle a fair bit of power based on the size. Post a picture of it?
S.O.S. JST connector identification - Page 1
Forum section: electronics / beginners

author: pedromorgan
author_rank: Newbie
timestamp: November 02, 2018, 07:36:11 pm
content: Really sorry to bother you folks.I have been trying desperatly to identify a particular connector.Its similar to a JST.... but not quite!I have been through catalogues but after a while, my eyes are just glazing over a sea of connectors!Pitch is 1.5mmPeter

author: sokoloff
author_rank: Super Contributor
timestamp: November 02, 2018, 10:03:19 pm
content: Molex PICO-SPOX, maybe?

author: pedromorgan
author_rank: Newbie
timestamp: November 03, 2018, 02:00:51 am
content: Thanks for the suggestion.I have ordered one to try it but I’m not convinced. The lip on the end of the Molex is larger than the ones I am trying to replace.But I will see!Thanks againPeter

author: pedromorgan
author_rank: Newbie
timestamp: November 08, 2018, 06:38:16 pm
content: it arrived this morning and was a perfect fit!Thanks for taking the time to reply. much appreciated.Peter

author: sokoloff
author_rank: Super Contributor
timestamp: November 08, 2018, 08:50:31 pm
content: IDing connectors is surprisingly frustrating. I've taken to ordering a bunch of samples of parts that "seem popular" so that I have them on hand for projects.
S-Parameters De-embedding using matlab/frequency vector problems - Page 1
Forum section: electronics / beginners

author: RFbeginner
author_rank: Newbie
timestamp: June 13, 2019, 01:12:43 pm
content: hello,I'm trying to deembed a DUT that has two connectors as fixtures i have the SP of the measured DUT+Fixture and the SP of the connectors,here is some of the code;Code:S_measured = sparameters('S2P-Hyb-41.s2p');S_fixture = sparameters('DeEmbeddedFixture.s2p');freq = S_measured.Frequencies;%% DUT De-embeddingS_DUT = deembedsparams(S_measured,S_fixture,S_fixture);it's the same connector but i used it twice so...BUT while running the code this shows up regarding the DUT Deembedding section:"All sparameter objects must use the same frequency vector and the same impedance value."both objects do have the frequenciescan anyone help me solve this ? i'm new to matlab and deembeddingboth files have a frequency range from 1.5 to 3.5GHz and both are on 50Ohm adjusted so i don't quite get it
S parameters of a connector!! - Page 1
Forum section: electronics / beginners

author: blackout123
author_rank: Newbie
timestamp: August 28, 2019, 10:28:28 am
content: Hello everyone,I am desperately trying to find the Scattering parameters of a connector. For that purpose, I designed two lines, one of length L and the other of length 2L.First idea was to use the T parameters to find the connector’s S parameters and the idea was as follow:Tmeasured_L = Tc Tline TcTmeasured_2L = Tc Tline Tline TcAnd then:  * -1 = Tc Tline Tc-1 = Ta-1 * Ta = Tc-1 Tc-1and then invert everything and square root… this is the matlab code but the result cannot be correctHello everyone,I am desperately trying to find the Scattering parameters of a connector. For that purpose, I designed two lines, one of length L and the other of length 2L.First idea was to use the T parameters to find the connector’s S parameters and the idea was as follow:Tmeasured_L = Tc Tline TcTmeasured_2L = Tc Tline Tline TcAnd then:  * -1 = Tc Tline Tc-1 = Ta-1 * Ta = Tc-1 Tc-1and then invert everything and square root… this is the matlab code but the result cannot be correct

author: rfeecs
author_rank: Frequent Contributor
timestamp: August 28, 2019, 06:04:07 pm
content: This is at least the fourth time you have posted the exact same question, previously under the user nameRFbeginner.I guess you were not happy with my answer:https://www.eevblog.com/forum/beginners/s-parameters-of-a-connector/msg2618190/#msg2618190Your equations are wrong. That's why your program doesn't work.Consider this:You have two unknown two ports: Tc and TlineThese are passive and reciprocal, so for each one S12=S21Tline is symmetric, so S11=S22So you have 5 unknowns:1. Tc(S11)2. Tc(S21) = Tc(S12)3. Tc(S22)4. Tline(S11) = Tline(S22)5. Tline(S21) = Tline(S12)You are measuring 2 symmetric devices, so S11=S22 and S12=S21 in your measurements.So you have 4 knowns to get 5 unknowns. It doesn't work.You have to make some assumptions. A common assumption is Tline is a perfectly matched 50 ohm line.S11=S22=0.That eliminates one of your unknowns and gives you 4 knowns and 4 unknowns. That is solvable.Now you just need to do the math correctly. It will be horribly messy algebra.
S parameters of a connector - Page 1
Forum section: electronics / beginners

author: RFbeginner
author_rank: Newbie
timestamp: August 15, 2019, 08:50:45 am
content: Hello everyone,I am desperately trying to find the Scattering parameters of a connector. For that purpose, I designed two lines, one of length L and the other of length 2L.First idea was to use the T parameters to find the connector’s S parameters and the idea was as follow:Tmeasured_L = Tc Tline TcTmeasured_2L = Tc Tline Tline TcAnd then:  * -1= Tc Tline Tc-1= Ta-1 * Ta = Tc-1Tc-1and then invert everything and square root… this is the matlab code but the result cannot be correctCode:%% S ParametersDataL = read(rfdata.data,'S2P-L.s2p');Data2L = read(rfdata.data,'S2P-2L.s2p');freq = DataL.Freq;SPL = extract(DataL, 'S_PARAMETERS',50);SP2L = extract(Data2L, 'S_PARAMETERS',50);%% S to TTPL = s2t(SPL);TP2L = s2t(SP2L);%% sizesize(TPL)length(TPL(2,2,:))%%for i=1:length(TPL(2,2,:))TA(:,:,i)=TP2L(:,:,i)/TPL(:,:,i);TB_1(:,:,i) = TPL(:,:,i)\TA(:,:,i);TB(:,:,i) = inv(TB_1(:,:,i));TC(:,:,i)=sqrtm(TB(:,:,i));endSC = t2s(TC);so next idea was to try and find every parameter at a time and I already determined the complex propagation constant, both alpha and beta and seems ok but kinda lost on how to find S11 and S22.Any ideas?thanks

author: rfeecs
author_rank: Frequent Contributor
timestamp: August 15, 2019, 06:26:43 pm
content: Quote from: RFbeginner on August 15, 2019, 08:50:45 amTo start with, this doesn't look right considering the connectors are reversed at the input and the output.This is similar to the "Thru Delay" method of test fixture de-embedding. If you have a network analyzer with an "adapter removal" function, it has built in math to do this as well, provided you have the appropriate calibration kits.This problem has been solved and there are many papers describing the messy algebra. Here is one:https://s3.amazonaws.com/academia.edu.documents/37546242/new_procedure_774.pdf?response-content-disposition=inline%3B%20filename%3DA_NEW_PROCEDURE_FOR_SYSTEM_CALIBRATION_A.pdf&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWOWYYGZ2Y53UL3A%2F20190815%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20190815T182108Z&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=c21ed26ee4903fd8deb689f2819df37c30ce04e1db73ce2bf7adf7b9d2d58276Here is another:https://ieeexplore.ieee.org/document/76424This one is paywalled. But it has a long list of references.
S-type load cell fundamentals question - Page 1
Forum section: electronics / beginners

author: V_King
author_rank: Regular Contributor
timestamp: October 21, 2019, 08:09:57 am
content: Hello,I need a couple of 500kg load cells. One local supplier has some 2000kg load cells he is happy to sell cheaper than 500kg ones. The load cells are same manufacturer, same physical dimensions, and same technical specs apart from the load rating. The sales guy is not most technically minded, and can not advice me.What fundamentally should I expect to have differently? As I understand I would have to have a greater gain for 2k load cell to achieve the same output under 0-500kg load? What would that lead to? greater noise? Reduced resolution (if I correctly understood the theory I was reading upon)? I tried reading upon load cell rating fundamentals, but just get a headache.Thanksp.s. this is not a discussion in regards to sales person technical knowledge. I rarely find one whom is capable of answering more fundament questions of the product working principles they sell.

author: ebclr
author_rank: Super Contributor
timestamp: October 21, 2019, 11:28:33 am
content: Electronically is the same circuit, Only the size of the S load cell is the difference ( and the price also ), Still, a resistance bridge does not matter what the load is, The unique difference is in software who will adjust the slope, gain, tpco and linearizationHow many units do you need ?
s10L271 thermistor - Page 1
Forum section: electronics / beginners

author: Snake-man
author_rank: Newbie
timestamp: April 26, 2022, 10:03:20 pm
content: HiIs someone know some information abouts10l271 thermistor?I need datasheet.Thanks

author: floobydust
author_rank: Super Contributor
timestamp: April 26, 2022, 10:21:21 pm
content: That looks more like a MOV part number i.e. 10D271 or S10K275.
S6613 based LED driver - Page 1
Forum section: electronics / beginners

author: czbaterka
author_rank: Contributor
timestamp: April 11, 2025, 07:59:14 pm
content: Hello,my LED driver broke today and the manufacturer is not selling replacement (ofc). I would have to buy whole new light fixture which I hate from both environmental and financial reasons, so I decided I will reverse-engineer the driver, try to build my own and learn about this type of drivers.It seems to be based on S6613 IC and the schematic looks like this (coil polarity is probably wrong, as thats something I cannot reverse engineer):The box of the LED driver have this specification:INPUT: AC85-265V 50/60HzOUTPUT: DC24-44V 280mA +-5%I was able to find that the IC is for "isolated flyback LED driver operating in discontinuous conduction mode (DCM)", but I actually never made something similar to this. I am well aware its dealing with mains voltage and I understand safety conserns, plus basics about SMPS.Seems like the driver is driving the LED strip (few dozens of LEDs in series) inside the light fixture with constant current, so would it make sense to find some equivalent schematic with more broadly available LED driver IC, set it to 280mA and use that, instead of trying to replicate/fix this one?
SAE 1978 - Page 1
Forum section: electronics / beginners

author: SUNNAM
author_rank: Newbie
timestamp: March 23, 2015, 01:09:21 am
content: I am going to develop SCAN TOOL (GST). Then please explain how to get certification of SAE 1978? (some tool has the certification seal)

author: Wilksey
author_rank: Super Contributor
timestamp: March 23, 2015, 11:49:16 am
content: Aha, the old SAE 1978 certification.I think I can answer this one.Look up on google who the issuing authority is, contact them, pay them a shit load of money and they will probably certify your scan tool, if it works and conforms to the standard that is.Or you could just buy one of the thousand that already exists and live in peace, love and harmony, whilst saving some time and money.I can see the appeal of making your own, automotive electronic design is so easy yet so much fun!

author: HighVoltage
author_rank: Super Contributor
timestamp: March 23, 2015, 09:08:14 pm
content: Once you have signed up with SAE and you are a full paid member, they can and will tell you all the details ... for a small fee.Or you become a review authority for them and get the information for free, in exchange for a lot of work that you do for them.
Saelig? - Page 1
Forum section: electronics / beginners

author: tony3d
author_rank: Frequent Contributor
timestamp: November 25, 2013, 03:06:28 am
content: Thinking of buying my first scope from Saelig. Has anyone dealt with them before?

author: IanB
author_rank: Super Contributor
timestamp: November 25, 2013, 03:07:25 am
content: Twice. Very good service.

author: mathsquid
author_rank: Frequent Contributor
timestamp: November 25, 2013, 03:28:19 am
content: I bought an OWON oscilloscope from them several months back. Had no trouble at all, and even got an educational discount.

author: tony3d
author_rank: Frequent Contributor
timestamp: November 25, 2013, 03:31:09 am
content: Quote from: mathsquid on November 25, 2013, 03:28:19 amHow do you like the Owon?

author: mathsquid
author_rank: Frequent Contributor
timestamp: November 25, 2013, 03:39:55 am
content: I've been quite happy with it. I have the SDS6062 which is a 60MHz scope. I've used it to decode IR signals, look at output from various 555 circuits, traced the output of a few microcontroller circuits, and other simple stuff. It's the only oscilloscope I've ever used, so I can't compare it with anything, but it works well I've been happy with it.

author: tony3d
author_rank: Frequent Contributor
timestamp: November 25, 2013, 04:36:14 am
content: Quote from: mathsquid on November 25, 2013, 03:39:55 amI'm torn between the Owon sds7102, and the Rigol 1102e. I must say I really like the large screen of the Owon.