hybridfree/eevblog-posts huggingface dataset:
Quality EPON modem manufacture? - Page 1
Forum section: electronics / beginners

author: sam1275
author_rank: Frequent Contributor
timestamp: April 29, 2015, 07:29:31 am
content: Hi everyone.I want to buy a EPON modem but all searches on google or ebay are just a few Chinese product, are there any quality EPON modem which is big-branded?If I search "fiber modem" there will be much more, but can I use that with a EPON ISP?Thank you!
Quality of voltagesource for MCU, certain sensors - Page 1
Forum section: electronics / beginners

author: eTobey
author_rank: Super Contributor
timestamp: March 11, 2023, 12:02:18 am
content: Hi,i am developing a brushless DC motorcontroller. I am not a professional, but im slowly collecting knowledge about it.I am wondering, how clean i have to make the rails for proper operation. At the Moment i plan to use 3 rails (12V, 5V, 3.6V). Generated from buck converters (42V input -AP66300). I wonder now if i can leave the voltage rail as is, or if i have to put some filterring after the buck.I tried searching for this subject, but i cant find the right keywords.

author: eTobey
author_rank: Super Contributor
timestamp: March 11, 2023, 07:26:20 am
content: I finnaly found some informations:In a forum, some said about the internal Regulator of a MCU, so i went to the datasheet.It seems to me, that i dont have to worry that much about it. But i recall, that dave said, Voltageregulator will pass riplle from the powerline?And there is one sentence, that makes me wonder, if a ripple influences it:"VBAT is the power supply for RTC, external clock 32 kHz oscillator"Can it influence the clock?

author: Psi
author_rank: Super Contributor
timestamp: March 11, 2023, 07:39:43 am
content: Often we add support for all these optional things on the first prototype PCB version. Then you figure out if they are actually needed after you build and test the first prototype. If you discover you need the filter then at least you have footprints on the PCB for it.If you don't have footprints for it then you have to bodge the components onto the pcb to get it working which is annoying.The pcb costs the same if you add a few extra pads for some filtering or you don't. Space on the board for extra parts is free as long as it doesn't make the overall pcb larger. You can add a footprint for a zero ohm resistor to bypass the optional circuit if it's not required. For the case of a filter you can just replace the R or the L in the RC/LC filter with the 0 ohm, so you don't need a special 'bypass' footprint.

author: eTobey
author_rank: Super Contributor
timestamp: March 11, 2023, 11:29:38 am
content: So from what i have read and understand, there is A, and B that give me a kind of stable output. And now i additionally add the same again to achieve even better results.But in this additionally step, there is a possiblity, that A starts to oscillate. Is it only, if the load is pulling current in the resonant frequency of the LC filter?
Quality probes and clips for through-hole and SMD? - Page 1
Forum section: electronics / beginners

author: Borillion
author_rank: Newbie
timestamp: June 22, 2023, 06:21:52 pm
content: Does anyone have recommendations for probes and clips for through-hole and SMD clips that are relatively affordable and somewhat robust?The last ones I purchased where not very robust, had weak "pincers" that would deform and release, required soldering to reattach wires that snapped at the solder joint.I would be connecting to pins and pin headers for the most part, examples of assorted connectors or devices I might work with, pads, vias, pogo connectors, eeprom or flash chips, connectors like around the Pi Pico and ESP32 SiP, etc.

author: jasonRF
author_rank: Regular Contributor
timestamp: June 22, 2023, 07:29:14 pm
content: I have used these and think they are pretty goodhttps://www.amazon.com/dp/B083PRVPCRbut I have only used them with soic and through-hole.I don't know how well they would work for finer pitches than soic.I just tried on some finer-pitched ICs and I couldn't get them attached. Perhaps the grabber wires are thicker than the space between the legs on the chips?The attached picture shows me using them on an soic8 eeprom as I fail to hack my picoscope (and to be clear, the clips worked great - the problem was that my trial and error changing of bytes didn't lead anywhere so I reverted the memory back to the original values).jason

author: Borillion
author_rank: Newbie
timestamp: June 22, 2023, 07:52:39 pm
content: Thanks. Those do look a bit better since they have the leads to connect to with the dupont ended wires, unless the pin breaks off LOL.I kind of went click happy today after posting and purchased a bunch of different styles on Amazon to out of frustration.Last one is about $100 but if the work it might be an interesting option.
Quality Short courses to doif taking bsc electrical and electronics engineering  - Page 1
Forum section: electronics / beginners

author: rodgi kibs
author_rank: Newbie
timestamp: December 10, 2024, 09:32:40 am
content: Which short courses can I be doing because I'm in a 9month from the system .Also Is machine learning worth taking for an electrical engineer and I so guide me of it's necessity and most suitable online course.thanks in advance

author: rstofer
author_rank: Super Contributor
timestamp: December 10, 2024, 02:12:15 pm
content: You can Google for 'applications for neural networks' to get a feel for the scope of applications. Facial recognition and voice recognition are obviously useful.
Quality Soldering Iron for SMT 0402 and above, IC's and microcontrollers ? - Page 1
Forum section: electronics / beginners

author: breakz
author_rank: Newbie
timestamp: August 11, 2017, 04:47:01 pm
content: Not too fancy, something around 40-50 USD/EURI have a Weller SPI-27C which I can use for 0603 and above but if I try to do 0402 it does not work for me.Anyone know if I can a get a thinner tip for this specific iron ?thanks.

author: KL27x
author_rank: Super Contributor
timestamp: August 12, 2017, 08:32:57 am
content: If I were going to buy something for SMD, today, and do it under $50, I'd probably put my chips down on a Yihua 939D.For 0402 stuff and point-to-point wiring of SMD IC pins, the T18 CF1 tip is pretty great.

author: julian1
author_rank: Frequent Contributor
timestamp: August 12, 2017, 11:15:45 pm
content: Have you tried a cheap hot-air gun/solder-paste and tweezers instead of a soldering iron?

author: breakz
author_rank: Newbie
timestamp: August 13, 2017, 08:36:21 pm
content: Quote from: julian1 on August 12, 2017, 11:15:45 pmyes and I like the hot-air solution too but I want to be able to do both ways.
quality T12 tips ? - Page 1
Forum section: electronics / beginners

author: bobbydazzler
author_rank: Regular Contributor
timestamp: July 18, 2021, 05:48:51 am
content: Anyone know what I need to look for when looking for decent quality tips for my new KSGER t12 soldering station? The station comes with a knife tip which I don't usually like and I've already ordered a cheap wedge D12 tip from ebay -https://www.ebay.com.au/itm/152869816964.I haven't had good experience ordering cheap tips from ebay for my Hakko clone in the past they oxidize really fast above 300c and I'm worried my new tips will have the same problem unless I can find a quality source.

author: ebclr
author_rank: Super Contributor
timestamp: July 18, 2021, 06:55:10 am
content: If you are so demanding, simply pay the premium for the original hacko ones, I use the ones from aliexpress and works like a champ, But I never go behind 320 C because I don't need that excessive temperature

author: bobbydazzler
author_rank: Regular Contributor
timestamp: July 18, 2021, 02:27:58 pm
content: 310c is the highest I use atm so if the sleep/standby function on the t12 works well I might not need to worry about it then.

author: wizard69
author_rank: Super Contributor
timestamp: July 18, 2021, 07:45:04 pm
content: Quote from: bobbydazzler on July 18, 2021, 02:27:58 pmJust buy the original Hakko tips and you will not have any problems. In the end buying decent tips will not cost you any more, if anything they will be cheaper in the long run.There are a lot of places where you can cut corners to keep the expense of the hobby under control, I do not believe that a soldering station is the place to cut those corners. This especially if you intend to do any fine work.Generally this advice holds for any tool you buy to support the hobby, make sure they are quality so you don't end up buying again in a months time. Now with so many player sin the market it can sometimes be hard to tell if anyone brand is in fact a robustly and accurately made tool. It is like flush cutters, there is a seemingly endless number of brands and prices you can pay; but if the blades don't line up, bend or break they are just a waste of money. More importantly they can lead to a lot of frustration. Same goes with soldering tips, tips that get crunchy way to fast just lead to frustration.
Quality WLAN amplifier one can actually buy? - Page 1
Forum section: electronics / beginners

author: Logan
author_rank: Frequent Contributor
timestamp: April 18, 2022, 03:12:37 pm
content: Hi.I'm looking for this for years, but still no satisfying answer.Just something similar to the picture, but from a reliable brand.I want it to be "power in, antenna in, antenna out", no software config needed. At least cover all 2.4 GHZ bands, and 802.11n compatible (It's better with 5Ghz ac and MIMO channel in one unit). At least 1 watt output, with bi-directional gain(also amplify received signal to host), and AGC.All I can find are either not a reliable brand, or cannot buy directly.Does anyone know a suitable one?Thanks.

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: April 18, 2022, 03:28:39 pm
content: How would it work with a weak device at the other end?

author: BrokenYugo
author_rank: Super Contributor
timestamp: April 18, 2022, 05:11:58 pm
content: Over 1 watt into the antenna is illegal, so you aren't going to find a reliable brand making such equipment.What exactly are you trying to do? Wifi range problems are usually not solved with more power.

author: free_electron
author_rank: Super Contributor
timestamp: April 18, 2022, 05:15:53 pm
content: Quote from: Ed.Kloonk on April 18, 2022, 03:28:39 pmtelephathy !I've always wondered about that.If we could just combine telepathy with large FPGA's... you just think about some functionality and the FPGA implements it. put a solar cell on the back (with a small battery for nighttime of course) of the FPGA.. imagine the possibilities ! no more mucking about with wires , or wifi or whatnot. no more need for development toolchains or VHDL or other crap.

author: Logan
author_rank: Frequent Contributor
timestamp: April 18, 2022, 06:33:47 pm
content: Quote from: Ed.Kloonk on April 18, 2022, 03:28:39 pmThat's why I want bi-directional gain.

author: Logan
author_rank: Frequent Contributor
timestamp: April 18, 2022, 06:35:16 pm
content: Quote from: BrokenYugo on April 18, 2022, 05:11:58 pmI did find a few, but they need quote, not selling directly.
quantum theory (tv series) - Page 1
Forum section: electronics / beginners

author: 3roomlab
author_rank: Frequent Contributor
timestamp: March 16, 2015, 05:49:30 am
content: i was watching this@ 13:57 ... how could that happen? the photon have 2 behaviors when watched/not watched?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 16, 2015, 06:16:40 am
content: Don't know what specifically they're talking about ("this video is not available"!), but you can rest assured, I think it's a theorem these days: all press/media reporting on quantum phenomena is uniformly somewhere between "bad" and "absurd".I assume the problem in question is one of superposition and/or entanglement? Possibly a double slit or interferometer experiment, something like that?I don't have a clue how the notion came into being that fundamental particles "know they are being watched by a conscious observer", but I can assure you, statements to that effect are on the "absurd" end of the spectrum. The explanation is far more mundane: however you arrange the experiment, when you "flip the switch" somewhere in there, you're simply changing the boundary conditions of the system, and therefore the expected result.Tim

author: pickle9000
author_rank: Super Contributor
timestamp: March 16, 2015, 06:28:16 am
content: The general theory is that the act of looking involves some form of light. It's that light that bombards the area and pushes things around.Have a look at an scanning tunneling electron microscope.

author: mtdoc
author_rank: Super Contributor
timestamp: March 16, 2015, 06:36:38 am
content: Can't watch the video either.But yes maybe trying to illustrate the effects of quantum entanglement (e.g Einstein's"Spooky action at a distance") or the collapse of quantum superstition, with the paradox as illustrated bySchrödinger's famous cat.
Quartz crystal loading capacitance - Page 1
Forum section: electronics / beginners

author: WimWalther
author_rank: Regular Contributor
timestamp: July 07, 2021, 07:39:57 am
content: How are loading caps selected for quartz crystals? For example..A design that uses a micro with external oscillator crystal calls for a 25MHz crystal and a pair of 33pF caps hanging off the osc pins to ground. Several 25MHz parts are available, with various capacitance specs - 16pF, 22pF, 33pF, 47pF, etcWhich value do I select & why?Thanks

author: Zero999
author_rank: Super Contributor
timestamp: July 07, 2021, 08:55:21 am
content: https://www.eevblog.com/forum/beginners/have-i-got-these-crystal-frequency-calculations-correct/https://www.eevblog.com/forum/beginners/oscillator-circuit-check-my-math/https://www.eevblog.com/forum/beginners/what-are-they-doing!-xtalosccaps/https://www.eevblog.com/forum/beginners/mcu-hse-crystal-choosing-the-right-capacitor/

author: jpanhalt
author_rank: Super Contributor
timestamp: July 07, 2021, 09:24:38 am
content: Presumably you are asking about the Pierce configuration used often for MCU.Simple (Pierce):https://community.nxp.com/thread/388856More detailed (also discusses Colpitts configuration):https://www.nxp.com/docs/en/application-note/AN3208.pdf
Quartz oscilator - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: October 27, 2020, 12:37:59 pm
content: I have an 19.2MHz SMD oscilator with 4 pins. One pin is XTAL_IN and the other is XTAL_OUT, next is GND and the last is Sensor pin.The oscilator is used in a device.Question: On which pin( s) should I measure its frequency 19.2MHz? Only on XTAL_OUT? Or also XTAL_IN?Thank you for replies

author: perieanuo
author_rank: Frequent Contributor
timestamp: October 27, 2020, 05:33:47 pm
content: hi, xtal_out

author: Jane
author_rank: Frequent Contributor
timestamp: October 27, 2020, 06:10:20 pm
content: It is as you said, so Xtal works OK.Thank you for the reply.
Quartz oscillator in place of a Quartz+Caps circuits for Esp32-H2 - Page 1
Forum section: electronics / beginners

author: Watth
author_rank: Frequent Contributor
timestamp: March 01, 2025, 07:55:18 pm
content: Hey everyone!I'm exploring the implementation of a ESP32-H2-MINI-1U.There is the possibility to add an external 32.768KHz with its accompanying caps:Can I use instead a Crystal oscillator (e.g.Seiko Epson X1B000211000100)From what I gathered, it is possible, by connecting the oscillator's output to the µCU's X_pos, and leave the oscillator' IO and the µCU's X_neg unconnected.If the external 32kHz clock is not implemented, the same pins can work as GPIO. If the oscillator is connected to X_pos, and X_neg is free, can the later's pin be used for GPIO?Thanks for reading!

author: xvr
author_rank: Frequent Contributor
timestamp: March 03, 2025, 03:17:00 pm
content: 32K quartz used in RTC circuit that should be run in various power saving modes. Epson Quartz oscillator consumes up to 2mA, so you can forget about power saving modes of ESP32. But without RTC and power saving modes there is no point in using 32K crystal.
help with oscillator with quartz crystal - Page 1
Forum section: electronics / beginners

author: alex123
author_rank: Newbie
timestamp: June 18, 2020, 05:51:17 am
content: hi, i have a problem with question C.searching the internet I found that the circuit was published in a magazine called ARRL handbook 2001 but I do not have access to the magazine.Can someone help me find the oscillator condition.

author: awallin
author_rank: Frequent Contributor
timestamp: June 18, 2020, 05:53:42 am
content: https://en.wikipedia.org/wiki/Barkhausen_stability_criterion?

author: alex123
author_rank: Newbie
timestamp: June 18, 2020, 06:02:39 am
content: Quote from: awallin on June 18, 2020, 05:53:42 amif I know the Barkhausen Stability Criterionbut I don't know what the feedback network is, it's not that easy
QUC simulator (Quite universal circuit Simulator) - Page 1
Forum section: electronics / beginners

author: rakeshm55
author_rank: Regular Contributor
timestamp: March 15, 2016, 07:22:43 am
content: I would like to start using QUC simulator ... I have used LTSpice and I am new to this tool ... is it worth??... Any suggestions/ advises welcome...(Circuit cellar - Robert lacoste - Dark side) recommends this tool for simulation exercises...https://sourceforge.net/projects/qucs/?source=directoryhttps://en.wikipedia.org/wiki/Quite_Universal_Circuit_Simulator

author: david-IT
author_rank: Contributor
timestamp: March 15, 2016, 09:28:20 am
content: also come to learn about it,hope someone can give the suggestion
QUERY REGARDING USING PCA9685 AND MOSFET - Page 1
Forum section: electronics / beginners

author: Ihtisham
author_rank: Newbie
timestamp: November 13, 2024, 02:59:37 am
content: Hi, I am planning to control 16 (12V, 3.3A) using PWM modulation. I will attach arduino with PCA9685 to control these fans. By question is how I can use mosfet with PCA9685, to amplify my voltage from 5V to 12V. PCA has three output pins. (Yellow, red and Black). How mosfet will be attached between source and PCA to control fan? and will each fan require a seperate mosfet. If there is any alternative solution for it, then it would be great. Thank you.

author: Harry_22
author_rank: Frequent Contributor
timestamp: November 13, 2024, 08:44:22 am
content: Hi!The title written in all capital letters seems a bit off-putting.

author: xvr
author_rank: Frequent Contributor
timestamp: November 13, 2024, 11:43:40 am
content: QuoteMOSFET Source pin should be attached to ground, Gate pin to PWM output, Drain pin to fan. Another fan pin connect to +12V. Also connect diode (in reverse) across fan.QuoteYes
Query: Source capacitor calculations for Ex-i Circuits with Zener barriers - Page 1
Forum section: electronics / beginners

author: aju11
author_rank: Contributor
timestamp: August 17, 2020, 02:35:19 pm
content: Should the capacitors connected before the safety barrier be considered for calculation of total allowed capacitance for Ex-i system?My project has a 24V DC SMPS with bulk capacitors (about 15000uF) followed by a safety barrier (fuse-Zener Diode-Resistor), a cable and a controller-sensor board.SMPS and barrier are in safe area (Ex-d enclosure ) and the cable and controller board are in hazardous area.Table A2 of IEC 60079-11 specifies limits to the maximum capacitance values.Query:Should the bulk capacitance (connected before energy barrier) be considered for calculation total capacitance along with the cable and controller board's capacitance?Please help!

author: aju11
author_rank: Contributor
timestamp: August 26, 2020, 09:03:14 am
content: Please Help!!

author: Tomorokoshi
author_rank: Super Contributor
timestamp: August 26, 2020, 04:35:04 pm
content: I understand the hesitancy of others to answer this question. The nature of the question along with the background information reveals that you may be taking on something that requires more experience.There is a lot that can easily go wrong with any hazardous location assessment or installation.Start with understanding how Table A.2 applies to your system. See Figure A.3 and determine the role of U and C and what values they take compared to yours. What does it mean for a source U to have some voltage? If one has an ideal voltage supply, does the concept of capacitance attached to the supply make any difference?Review 60079-11 Annex A.Review 60079-14 Annex A.Review 60079-25 Annex A.There is a lot more that needs to be considered and understood here. Be careful how you proceed, as a satisfactory answer here does not mean your system is safe.
Question  - Page 1
Forum section: electronics / beginners

author: Russ
author_rank: Regular Contributor
timestamp: January 11, 2018, 04:32:45 am
content: If six 3v/200mA-rated photovoltaic cells that are connected in series and six more 3v/200mA rated photovoltaic cells also connected in series and placed in parallel with the first set of six, what is the total voltage of the combination of photovoltaic cells?Thanks

author: mtdoc
author_rank: Super Contributor
timestamp: January 11, 2018, 04:42:33 am
content: The same as each separate series string - that is 6 x 3V = 18V.The amperage adds for parallel PV strings, not the voltage, so you'll end up with a nominal 18V, 400 mA array.

author: IanB
author_rank: Super Contributor
timestamp: January 11, 2018, 04:43:47 am
content: If you put six 3 V, 200 mA supplies in series, you get an 18 V, 200 mA supply.If you put this 18 V, 200 mA supply in parallel with another 18 V, 200 mA supply, you get an 18 V, 400 mA supply.The rule to remember is that series voltages add up, parallel currents add up.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: January 11, 2018, 04:44:15 am
content: Hmm, hope this isn't a joke, but 6 X 3 volts(series)=18 volts @ 200mA + 18 volts @ 200mA (series) in parallel with first series is still 18 volts @ 400 mA output (if the spec numbers can be trusted).

author: Russ
author_rank: Regular Contributor
timestamp: January 11, 2018, 04:46:47 am
content: Quote from: tpowell1830 on January 11, 2018, 04:44:15 amNo, not a joke. Thank you VERY much. 👍Russ

author: tpowell1830
author_rank: Frequent Contributor
timestamp: January 11, 2018, 04:52:15 am
content: You're very welcome.

author: digsys
author_rank: Unknown
timestamp: January 11, 2018, 05:31:43 am
content: NOTE: They may not share perfectly in parallel though. You need to keep them both aligned perfectly. In some cases, you may not achieve thefull 400mA, but should be close
Question about a 12V Power PMOS Switches - Page 1
Forum section: electronics / beginners

author: Mr.sun
author_rank: Newbie
timestamp: August 01, 2020, 06:42:21 am
content: Hi everyone,there is diode(named 'D1') in the circuit of MiniPC.PrjPcb Project (one example from AltiumDesigner),but the Q20(Si7635DP-T1-GE3) has drain-source body diode,my question is:what's the function of the D1?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 01, 2020, 07:01:28 am
content: Idunno. Lower voltage drop? Potentially higher surge current rating?Could use a TVS on the input as well. Maybe filtering if there's noisy stuff elsewhere, too. But eh, it's only an example, I wouldn't put much confidence in its electrical design, whatever it is.Tim

author: MasterT
author_rank: Frequent Contributor
timestamp: August 01, 2020, 12:00:09 pm
content: If D1 is a zenner, than OVP above 20V.

author: Mr.sun
author_rank: Newbie
timestamp: August 01, 2020, 01:04:24 pm
content: Quote from: MasterT on August 01, 2020, 12:00:09 pmD1 is B530C-13-F， a Schottky Diode 3.

author: MasterT
author_rank: Frequent Contributor
timestamp: August 01, 2020, 01:25:43 pm
content: Schottky doesn't make any sense, but zenner may save mosfet for short transient OVP, static discharge etc.

author: David Hess
author_rank: Super Contributor
timestamp: August 01, 2020, 07:09:56 pm
content: A parallel schottky diode is common where the body diode should not be forward biased because its recovery time will short out the switch when commutated, but this hardly applies here. You can see this in synchronous switching regulators.The body diode has the same voltage and current rating as the power MOSFET. Is there a possibility of reverse current through the MOSFET's body diode which is higher than the current rating of the power MOSFET? I see that big capacitor slowing turn-on time which would limit current in the forward direction.
Question about a datasheet - Page 1
Forum section: electronics / beginners

author: king.oslo
author_rank: Frequent Contributor
timestamp: October 17, 2013, 09:03:02 pm
content: Hello there,Looking at the FEI rubidium datasheets. The one which Dave got has a short term drift of 10^-11/ day.Here is the datasheet:http://www.freqelec.com/rb_osc_fe5680a.htmlMy question is, 10^-11 relative to what? 10MHz? 1Hz? Some other unit, or something else altogether?Thanks,Marius

author: KJDS
author_rank: Super Contributor
timestamp: October 17, 2013, 09:05:50 pm
content: It's a ratio.So as it's a 10MHz oscillator, then 10^7Hz * 10^-11 gives 10^-4 per day, or 0.1milliHz per day.
Question about a F Type coax surge suppressor board - Page 1
Forum section: electronics / beginners

author: bugalou
author_rank: Newbie
timestamp: March 13, 2015, 01:57:09 am
content: I recently broke down a non functional APC ES BE725BB UPS. I now want to re-purpose the the coax surge suppressor board. Unfortunately I tossed the case/housing in the recycling bin weeks ago and have no idea which side is the input side, and which is the output side. The board's mounted components are under a metal shield that is soldered to the board. I was hoping I could get some guidance on figuring this out from the traces on the rear of the board with a multimedia. I would like to avoid having to desolder the shielding if possible.I had no luck trying to find a schematic of the UPS online, nor even some pictures of the unit opened up. Pictures are below:

author: benjamin545
author_rank: Contributor
timestamp: March 13, 2015, 04:02:26 am
content: i dont know if what you have is a typical surge suppressor that im use to but ill describe what you often install out in the field for coax surge suppression for broadband TV or CCTV.basically you have these rectangular metal cans with an f terminal marked equipment and an f terminal marked field. if you open them up and look insideand the center core of the input has a bare wire that goes straight over to the output terminal and halfway between there is a trans-orb that goes to the metal casing.essentially, there is no real input and output, its just a straight through connection with a transorb to ground, if you get enough of a + or - voltage the transorb will conduct to ground and crowbar the surge.what you have there MAY be different but i really doubt it.

author: babysitter
author_rank: Frequent Contributor
timestamp: March 13, 2015, 07:08:14 am
content: The shunted current shall go to ground the shortest possible way, so I vote on the side with the "GRN" terminal as being antenna port.

author: bugalou
author_rank: Newbie
timestamp: March 13, 2015, 01:29:35 pm
content: Thanks for the replies. Like Ben said, I am thinking it doesn't matter, and the antenna being close to ground makes sense too.
Question about a schematic with a 100K resistor - Page 1
Forum section: electronics / beginners

author: uk.casmith
author_rank: Contributor
timestamp: June 22, 2020, 08:49:31 pm
content: Hello,I'm going through an electronics book and the author has a 100K resistor added to the noninverting input pin of the comparator, and has the output connected to it to provide positive feedback.I don't understand why we need the 100k resistor in this schematic? I understand that the IC pin must have a very high Independence that it won't make much difference, but I just don't get why he would add it?Please see attached photo.Any help would be appreciated.Thanks,Cameron.

author: TimFox
author_rank: Super Contributor
timestamp: June 22, 2020, 08:59:08 pm
content: The 100k resistor and the 500k pot form a voltage divider to adjust the magnitude of the positive feedback. I assume that is to adjust the hysteresis.

author: uk.casmith
author_rank: Contributor
timestamp: June 22, 2020, 09:05:57 pm
content: Wow, yeah that makes sense.I'm new to electronics and i've only seen very simple voltage dividers that start at use the same path eg:5 volts >> Resistor >> Resistor >> gndIn this case the transistor could be providing less voltage like 3.5 volts and the output voltage could be providing 4.5 volts. Not really sure how that works?Cheers,Cameron

author: Zero999
author_rank: Super Contributor
timestamp: June 23, 2020, 01:01:00 pm
content: The output voltage of the phototransistor, depends on how much light is shining on it.The circuit would be easier to understand, if propper symbols were used for the comparator, rather than just showing the package, which isn't much use, without referring to the data sheet.
question about Amps and 12V - Page 1
Forum section: electronics / beginners

author: eevfan007
author_rank: Contributor
timestamp: August 26, 2015, 09:06:54 pm
content: Im building a fish pond in my garden.I bought a big 230v AC to 12v DC transformer, that can deliver up to 10 A.From that 12v I connect miscellaneous LED lamps. All the LEDs have their own driver boards on them, so in that sense I should be fine.My question is... Am i correct in my assumption that as longs as the transformer can deliver more amps than what I actually use, I will be fine?I can't damage the LEDs by being theoretically able to deliver 10 amps right ? That the problem only occurs when I have LEDS that require more than what I can supply ?I also have a fuse in the circuit too.Thanks for making this clarification.Are there any dangers, gotchas or general advice you guys have on keeping a 12V system like this safe?I have encapsulated everything in waterproof enclosures etc...Thanks

author: Hideki
author_rank: Frequent Contributor
timestamp: August 26, 2015, 09:12:14 pm
content: You are correct, and it sounds like you're doing everything right

author: Delta
author_rank: Super Contributor
timestamp: August 26, 2015, 11:45:09 pm
content: You are spot on mate.Only thing to watch for is that the 12vDC psu is a proper SELV item, and thus safe to power stuff outside and in a pond,.

author: rickselectricalprojects
author_rank: Regular Contributor
timestamp: August 26, 2015, 11:54:36 pm
content: yep it will work fine

author: Rick Law
author_rank: Super Contributor
timestamp: August 27, 2015, 03:30:34 am
content: Quote from: eevfan007 on August 26, 2015, 09:06:54 pmI suggest keeping it away from direct sun light as well. UV from the sun destroys most plastic.I had an outdoor fish/frog mini-pond (just a large plastic tub). My pump, lights, (winter) water warmer connections were all encased in plastic boxes but under direct sun light! Some time into year two, the plastic was so weaken by the UV rays from the sun my plastic casing had many many tiny cracks. It crumbled into bits just because of the force of trying to pick it up...

author: fivefish
author_rank: Frequent Contributor
timestamp: August 27, 2015, 03:37:43 am
content: QuoteDid you buy a power transformer? or a power supply?A power transformer will be outputting AC on it's secondary, not DC.

author: Joule Thief
author_rank: Regular Contributor
timestamp: August 27, 2015, 04:10:30 am
content: Quote from: fivefish on August 27, 2015, 03:37:43 amI believe he may have intended to say a 230 VAC to 12VDCpower supply- and it came out as "transformer".Quote from: eevfan007 on August 26, 2015, 09:06:54 pmI hope you enjoy the serenity a fish pond will offer.

author: homebrew
author_rank: Frequent Contributor
timestamp: August 27, 2015, 07:00:30 am
content: Quote from: eevfan007 on August 26, 2015, 09:06:54 pmMaybe you should add fuses for the individual boards. Depends on their specification ...10@ 12V equals 120W of heating power when things go wrong.
question about amps - Page 1
Forum section: electronics / beginners

author: shane_95
author_rank: Regular Contributor
timestamp: July 19, 2012, 06:26:23 am
content: I have a 9V 2A transformer, i hooked it up to my 12v 34mA fan. my question will than only draw the 34mA and leave me with 1.966A?

author: Classicmacintosh
author_rank: Newbie
timestamp: July 19, 2012, 07:14:34 am
content: If the fan is a brushless DC type then current draw will most likely be reduced to some extent, probably to roughly 25-30mA.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 19, 2012, 10:13:39 am
content: Quote from: shane_95 on July 19, 2012, 06:26:23 amSorry,Shane,but you have a strange way of phrasing questions.As Classicmacintosh said,the motor will probably draw a bit less at the reduced voltage,however,for the sake of argument,we will go with 34mA.With no other load connected to the transformer, that will be theonlycurrent in the circuit.The transformer can now,if a load drawing 1.966A is connected inparallelwith the motor,deliver that current as well,for a total draw of 2A,On that basis,you can say that your transformer after supplying the motor,still has the capability of supplying a further 1.966A.

author: T4P
author_rank: Super Contributor
timestamp: July 19, 2012, 01:55:30 pm
content: Quote from: shane_95 on July 19, 2012, 06:26:23 amlol no.Unless it's a DC-DC Conv then will the V=I/R law apply.So it will draw less than 34mA at 9V, because the literal resistance at 12V is 352ohmsso at 9v it draws only 25.5mAAnd so the transformer is loaded at 25.5mA leaving the rest possible for another deviceBUT it only applies if it's at 9V ... if it's a linear unregulated transformer you see more than just 9V

author: digsys
author_rank: Unknown
timestamp: July 19, 2012, 02:25:44 pm
content: Quote from: shane_95 on July 19, 2012, 06:26:23 amAnother way to explain this is -P=VxI so the transformer can supply 18VA of Energy (AC). If you add a bridge to make DC, you still have the SAME ENERGY available,(- the diode loss of the bridge, which we'll ignore for now) BUT VDC= 1.4X VAC and IDC = IDC / 1.4 (again, forget losses for now)So for simplicity, you have 18VA (or WATTS) of power available.The fan draws 9VDC x 0.04A = 0.35W (close enough), which leaves you with 17.65W available BEFORE the Transformer OUTPUT startsto drop, and heat up. You CAN do this with just AMPS, as the others have suggested, both methods are fine.SOMETIMES, it is easier to visualise what you have available using POWER. You need to be fluent with the primary relationships -V=IR, P=VI and the variations, you'll use these ALL the time !!
Question about AoE 3rd (MC34063 example) - Page 1
Forum section: electronics / beginners

author: EngKyr
author_rank: Newbie
timestamp: February 25, 2018, 08:01:14 pm
content: I everyone,I was reading the example about buck converter at page 644 and I went troght the calculations.On the book is writted ton/off = 6 and ton = 17usec. It should be ton/off = 0.6 and ton = ~7usec.Am I write or I missing something?thank you in advance!
Question about battery amp-hour ratings - Page 1
Forum section: electronics / beginners

author: fubar.gr
author_rank: Unknown
timestamp: December 12, 2016, 03:37:42 pm
content: Most batteries of any type will have a capacity rating in amp-hours or watt-hours printed on them.But at what discharge level do these numbers refer?Eg, Automotive lead acid batteries have capacities ranging from 35 Ah up to 100 or more. Does this refer to discharging the battery from 12.8 Volts to 10 Volts ? Or until the voltage drops to zero?

author: NottheDan
author_rank: Frequent Contributor
timestamp: December 12, 2016, 04:24:51 pm
content: To the cut-off voltage.http://web.mit.edu/evt/summary_battery_specifications.pdf

author: tszaboo
author_rank: Super Contributor
timestamp: December 12, 2016, 05:52:25 pm
content: Quote from: fubar.gr on December 12, 2016, 03:37:42 pmIt makes very little difference, as 98+% of the capacity will be above 10V. The tolerance of the capacity will result a bigger error.

author: sibeen
author_rank: Frequent Contributor
timestamp: December 26, 2016, 09:59:11 am
content: Like many things in the electrical field you have to be careful and read the spec sheets carefully to do any valid comparisons.For a standard lead acid battery the amp hour rating of the battery is given as the multiple of amps and hours(Doh). As an example if a battery can supply 10 amps for 10 hours it then gets labelled as a 100A/h battery. The technical bit is in how long a battery is actually discharged over. There are at least five rates that I've seen used, the 10 hour rate being the most common. As a battery is an electrochemical device normally the longer the discharge is undertaken the more energy that can be withdrawn for it. A battery that can produce 100 amps for 1 hour (100 A/h) would be expected to be able to produce substantially more if the discharge was extended to 10 hours, so you may see something in the order of 13 amps for 10 hours = 130 A/h.The rate of discharge used is called the "C" rating, so a battery given as 100 A/h C3 means that the battery has given 33 amps for 3 hours; conversely a battery rated at 50 A/h C10 means 5 amps for 10 hours.The C10 standard is far and away the most common, but I have seen C1, C3, C8 and C20 also used. The C20 was obviously pulled out by some marketing genius who realised he could get a few extra amp hours out of a battery by extending the discharge time.

author: Rick Law
author_rank: Super Contributor
timestamp: December 27, 2016, 05:10:05 am
content: Note also that the capacity depends greatly on the output current. The SLA I have for emergency has multiple ratings listed: Four different Current and their corresponding AmpHour.
Question about BNC test leads versus regular test leads - Page 1
Forum section: electronics / beginners

author: kleblanc
author_rank: Unknown
timestamp: January 31, 2016, 02:04:38 pm
content: I am looking for some general information about BNC vs regular single wire test leads. What I have found is BNC is generally rated for up to 500V and has dielectric shielding for frequency up to 4 GHz. I am more or less looking at the BNC/banana/mini-grabbers used with DMM test equipment. I like the BNC setup since it keeps multiple leads from becoming a rats nest.My questions areThe pros and if any cons of BNC test leads.Are there specific reasons not to use BNC?Thank you.

author: Ranger14
author_rank: Regular Contributor
timestamp: January 31, 2016, 02:25:40 pm
content: How much current can a bnc handle ??

author: uncle_bob
author_rank: Unknown
timestamp: January 31, 2016, 04:32:07 pm
content: HiIf you are talking about a volt meter, the BNC / coax setup will add a bit more stray C to your measurement. That's not much of a deal at low frequencies. It can be an issue in some cases.The bigger question is - what are you doing? If you have a multimeter and are checking a circuit, the ground may well clip on way over there and you are probing quite a ways away. That works fine with normal test leads, not so well with BNC stuff. If you have an RF circuit and want to get accurate numbers, some sort of probe will be a better way to go than any sort of test leads. Essentially a probe is a special case of a BNC / coax test lead. They have worked a bit on the stray C issues and improved it's performance a bit.The other question seems to be - is there a magic way to avoid a rat's nest on my bench? The simple answer to that one is - no. You will have wires and cables all over the place.Bob

author: uncle_bob
author_rank: Unknown
timestamp: January 31, 2016, 04:38:48 pm
content: Quote from: Ranger14 on January 31, 2016, 02:25:40 pmHiBNC's depend on the spring contact in the middle to keep a low dc resistance. Depending on how long you use them, that contact gets pretty worn out. They start out with a 2A rating and go down from there. They are not intended as a power connector. They are a test signal connector.Surprisingly, banana plugs are very similar. They get rated all over the place (some say 3A max, others 5A, others 30A). In the real world after some use, they may get pretty warm at 3A. Tweak the springs a bit and they cool back down.Crazy stuff.Bob

author: kleblanc
author_rank: Unknown
timestamp: January 31, 2016, 04:46:00 pm
content: Thank you for the info. I typically work on controls measuring/supplying 24VDC 4-20 ma loops along with resistance measurements. So everything is within lead reach most of the time. I was wondering if this is ok or not recommended.Sorry for the ignorance, what is stray C and how would this affect my measurements if at all.Thanks!

author: uncle_bob
author_rank: Unknown
timestamp: January 31, 2016, 05:51:23 pm
content: HiStray C = stray capacitance. If you have an AC signal at high frequencies it can be an issue.Bob
Question about CAN bus physical layer - Page 1
Forum section: electronics / beginners

author: no1no2no3no4
author_rank: Newbie
timestamp: February 13, 2023, 08:36:00 am
content: I'm attempting to understand CAN bus and there is an aspect about the physical layer that I cannot wrap my head around. I'm looking at this (https://www.ti.com/lit/an/sloa101b/sloa101b.pdf) document made by TI explaining CAN bus (also attached in case link rots). In figure 8, some CAN bus traffic is shown, and I don't understand the voltages shown on the CAN bus/channel 1. The voltages seem to be inverted from what I would expect. For example, on the left hand side of the image when only node A is transmitting I would expect the CAN bus to show identical voltages to node A but it seems to show inverted voltages to node A. What is the process that is inverting the voltages here? In my mind, I'm thinking that for the time when only node A is transmitting, we can ignore all the other nodes on the network and consider a "network" of only 1 node, node A. In this simplified case, wouldn't node A and CAN bus voltages simply be the same? Is this a valid simplification? From what I understand is that all of the nodes are in parallel so they should simply always have the same voltage across them(not accounting for the time it takes for the signal to propagate) correct?

author: no1no2no3no4
author_rank: Newbie
timestamp: February 13, 2023, 09:08:29 am
content: Ok, now that I'm looking at it more, I'm wondering if maybe they just have the voltage flipped on the oscilloscope for all the nodes but not the CAN bus. As I understand, the recessive bit should be low and each node seems to be high when not sending data. Also the ACK bit should go high and on the scope it goes low. Would be weird if they set it up like this...

author: Jeroen3
author_rank: Super Contributor
timestamp: February 13, 2023, 09:34:14 am
content: Figure 8 shows 3 outputs of the transceiver on the TTL side, not the CAN side. Only channel 1 is one of the CAN bus lines. Of which there are 2. And one of which is inverted from the other. See figure 9.

author: no1no2no3no4
author_rank: Newbie
timestamp: February 13, 2023, 05:12:13 pm
content: So it seems my misunderstanding was with the setup of the oscilloscope in this case.Now, if I understand it correctly, the voltage displayed is the voltage at each node, referenced to ground. I'm not sure I understand what TTL means, is this transistor-transistor logic? So on the TTL side, the signal is inverted? I can't find those exact symbols anywhere, they seem to be the transmitter and receiver?And then the voltage displayed for the CAN bus is the voltage referenced to ground on CANH, which is why the voltage goes high for the dominant bit. And CANL would be inverted from CANH.

author: langwadt
author_rank: Super Contributor
timestamp: February 13, 2023, 05:30:21 pm
content: the node a/b/c is before the transceiver that drives the busthe transceiver inverts, see fig. 4
question about capacitors - Page 1
Forum section: electronics / beginners

author: Solaris
author_rank: Newbie
timestamp: October 21, 2014, 03:14:12 pm
content: hi, i have a silly questionok, say for instance we have a 10 volt 1000uf capacitorbut we only put say 5 volts into it... would it now be equivalent to a 5 volt 1000uf capacitor?that is to say, would the energy stored be equal to a 5 volt 1000uf capacitor charged to 5 volts?this confuses me because i see PSU's with 20 volt capacitors on the 12 volt railit makes me wonder if the capacitance is the same at almost half the voltage.thanks

author: ElektroQuark
author_rank: Unknown
timestamp: October 21, 2014, 03:16:55 pm
content: Yes.The marked voltage is the maximun voltage the capacitor is reliable for.At same charged voltage, equal capacity capacitors store the same energy.

author: Simon
author_rank: Unknown
timestamp: October 21, 2014, 03:17:10 pm
content: The capacitance is always the same. Electrolytic capacitors are like high speed batteries and have liquid acid in them so you NEVER run them full voltage or temperature that is why your 12V PSU wisely uses 20V capacitors. The behavior will be the same regardless of voltage but over-voltage permanently damages them quickly and no good designer uses them at their rated voltage (yes i has taken some stuff apart designed by clods).

author: Solaris
author_rank: Newbie
timestamp: October 21, 2014, 03:31:58 pm
content: thanksthis explains the mystery.

author: Jeroen3
author_rank: Super Contributor
timestamp: October 22, 2014, 08:22:33 am
content: A recent EEVblog episode went into some details of ceramic capacitors and a possible trap for young players regarding this issue.Might be related.

author: Simon
author_rank: Unknown
timestamp: October 22, 2014, 08:47:33 am
content: That was a different problem and regarded specific type of capacitors in tiny surface mount packages
Question about Car Battery Analyzers - Page 1
Forum section: electronics / beginners

author: nowlan
author_rank: Frequent Contributor
timestamp: August 05, 2015, 02:58:57 pm
content: Hello,I was curious about some car battery analyzers. They claim to use conductance, which is 1/R from memory.Battery University LinkSome examples:1.Cen-Tech(Internals)2.Ctek3.SolarWould I be able to do the same with a multimer or ESR meter?

author: saturation
author_rank: Super Contributor
timestamp: August 05, 2015, 04:05:40 pm
content: Yes. Just insure your AC source has a blocking capacitor to protect the signal output circuitry. The battery's output impedance correlates poorly with Ah, but its an index of battery aging. Its more accurate to burn test a battery.EIS or Dielectric spectroscopy is basically a spectral signature of a healthy vs unhealthy battery. Instead of using one frequency as the standard AC test, it uses several frequencies. You could consider the battery as a variable capacitor, as it ages the capacitance changes so the frequency response changes too. AFAIK, no one knows the optimal frequency or combinations of them. This is probably what the cadex patent is about.http://lygte-info.dk/info/Internal%20impedance%20UK.htmlhttp://www.flippers.com/esrkthnt.html#batteryI wouldn't be surprised if the practical task is to inject a square wave instead of sine and getting the Fourier signature, as an index.