hybridfree/eevblog-posts huggingface dataset:
"Generic" Spectrum Analyzer tutorial, demo old Tek 1401A - Video - Page 1
Forum section: electronics / beginners

author: w2aew
author_rank: Super Contributor
timestamp: October 24, 2011, 03:03:20 am
content: I recently picked up an old Tektronix 1401A Spectrum Analyzer Module from the mid 1970s, and it inspired me to to put together this short video to review the basic architecture of a conventional swept Spectrum Analyzer. I hope you all find it helpful.73,Alan W2AEW@AlanAtTek

author: codeboy2k
author_rank: Super Contributor
timestamp: October 24, 2011, 04:46:37 am
content: Wow. Awesome tutorial, well presented. Thanks so much for taking the time to put this together.-- Cheers!

author: SgtRock
author_rank: Unknown
timestamp: October 24, 2011, 04:53:19 am
content: Dear Alan:--Great post. I enjoyed it very much. We used to use a version of these, called panoramic receivers. Same output you showed except we would have little markers at the bottom showing where our receivers were tuned. Because the radio frequencies looked like blades of grass on our green scopes, tuning to a signal was called mowing the grass. You would just move your little marker to the spike, and viola you could hear the signal. Radio stations and other constant sources would be there all the time. What interested us were the "Push To Talk" spikes. And what was most interesting of course was "Complex Working" where signal A would come up for a few seconds then signal B would come up for a few seconds followed by signal A...and Bobs you uncle. I would venture to say that, even with encipherment and frequency hopping, these things are still proving useful in many cases, to the FCC and probably to some other folks, whom I will not mention here."Marconi invented the radio but he had to wait years and years till anything decent was on." Johnny CarsonBest RegardsClear Ether

author: w2aew
author_rank: Super Contributor
timestamp: October 24, 2011, 03:43:37 pm
content: Quote from: SgtRock on October 24, 2011, 04:53:19 amThanks for the nice comments. You'll probably like the "search marker" functionality of this 1401A as shown in this short video:The panoramic receiver is interesting. This type of swept analyzer would be useful to sweep the band for the "grass". Then, if you move the marker to the blade of interest, you can adjust the SPAN to zero and AM demodulate. I don't know if there was a FM demodulate option for this analyzer - I'd have to look that up!Some of today's modern real-time spectrum analyzers can also give you the functionality of the panoramic receiver. With these units, you can continually "stare" at up to 110MHz of real-time "live" spectrum, and place markers on signals of interest, and listen to any one that you choose. Hmm, I might have to make a short video about that too...Alan

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 24, 2011, 03:55:27 pm
content: thanx alan for that educational video.
"Home made" LCD panel + HDMI to VGA issues - Page 1
Forum section: electronics / beginners

author: step_s
author_rank: Regular Contributor
timestamp: November 12, 2016, 03:35:45 pm
content: Hi EEVersI made a screen from an old labtop LCD and the MT6820-D monitor driver, and it works like it should when run over VGA.I then tried hooking it up to my main computer through a passive HDMI to VGA converter, and this makes the screen turn on for 1sec with the desktop showing, then goes black, and shows "no signal" for a couple of seconds, then just loops like this.The converter works without problems with a normal VGA compatible screen.So the home made screen works, and the converter works, but they don't work together :/Any thoughts? Could the passive converter trip the monitor driver chip in some way?

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: November 18, 2016, 05:59:43 pm
content: HDMI signals are digital 0's, and 1's. VGA is Analog. With the right converter, maybe it works...?You might have HDCP issues as well if you try displaying copyrighted material.http://www.tomshardware.com/forum/id-3133491/hdmi-vga-converter-work.html

author: janoc
author_rank: Super Contributor
timestamp: November 18, 2016, 10:01:10 pm
content: Oh and don't forget that many cheap HDMI->VGA converters take power from the HDMI connector intended to drive the EDID EEPROMs in monitors/TVs (there is no such thing as "passive" HDMI to VGA converter). The amount of current available on these ports is often insufficient and the problems you have could be well thanks to that.This is a typical example of such converter:https://www.aliexpress.com/item/HDMI-to-VGA-Cable-HDMI-Male-to-VGA-Female-HDMI-to-VGA-Video-Converter-Adapter-Cables/32722750678.htmlMost HDMI ports will not be able to deliver the amount of current this thing needs and you could even fry your device with it. I have hacked one of these to give it external power from a nearby USB port, then it worked OK (well the image quality sucks, but you get what you pay for).
"Hot glue" sensitive components - Page 1
Forum section: electronics / beginners

author: kalel
author_rank: Frequent Contributor
timestamp: November 29, 2017, 09:28:16 pm
content: When using hot glue with prototype boards to provide support for components, wires, or otherwise, which components are sensitive enough that they would or could be damaged from the heat of applying hot glue to them?I realize there are different hot glue types and even temperatures, but I don't have specific information to provide, I'm just interested generally/broadly in what should be avoided when working with hot glue.

author: ataradov
author_rank: Super Contributor
timestamp: November 29, 2017, 09:32:11 pm
content: All components will be fine. Hot glue is not that hot. Components are designed to go through the soldering process, which is way more high temperature.

author: KL27x
author_rank: Super Contributor
timestamp: November 29, 2017, 10:05:57 pm
content: I use hot glue on those little inductors, where the wire is wound around a fragile ferrite spool. Left naked, they break at the slightest bump. The only tricky part is removing the glue if/when you need to without breaking these fragile parts. I keep the glue bathed in alcohol with a brush while picking it apart with tweezers.The only component I have found which is really sensitive to hot glue is not from the heat, but from the alcohol. (In case you ever want to remove the glue from nearby components.) The cap/lid of the plastic housing of the flat SMD piezos will tend to fall out when exposed to solvent. They are (at least in some cases) glued in place rather than welded.

author: retrolefty
author_rank: Super Contributor
timestamp: November 29, 2017, 10:12:32 pm
content: Well off hand I would say hot glue is not useful and possibly harmful for several electronic components thatthat physically move, turn or rotate. Like variable capacitors, potentiometers, roller inductors, exposed relay contacts, motor rotors. Maybe some others?

author: ataradov
author_rank: Super Contributor
timestamp: November 29, 2017, 10:15:33 pm
content: Quote from: retrolefty on November 29, 2017, 10:12:32 pmThe question was about thermal damage.Obviously don't interfere with physical movement of the components.

author: Greg Robinson
author_rank: Regular Contributor
timestamp: November 29, 2017, 11:22:03 pm
content: Polystyrene capacitors.

author: retrolefty
author_rank: Super Contributor
timestamp: November 30, 2017, 12:00:06 am
content: Quote from: ataradov on November 29, 2017, 10:15:33 pmMy comment was meant to be somewhat tongue in cheek but forgot to include some emoticon.Maybe
"Increase" gate threshold voltage for HV high dv/t? - Page 1
Forum section: electronics / beginners

author: rentner
author_rank: Regular Contributor
timestamp: September 29, 2017, 06:45:13 am
content: Hey folks, I want to build a H Bridge with high current capabilities, high speed (>200khz) short turn on/off times and a relative huge voltage for that stuff of >300V rail/-rail.If the low side N-Fet pulls down, the high side Mosfet always turns back on and creates shoot through. This of course only happens because it is an inductive load. (Filter)The Turn-Off diode basically does nothing for the 1V threshold - it barely conducts any current.I think of using HF Mosfets with 6nC total gate charge for very dast and easy switching, but the tiny gate threshold voltage of 1V at this high dv/t conditions has almost no chance to stay off. Gate driver uses BJT output stage - as my fetish implies - it is discrete. The high side driver works at "light speed" and runs stable, but the Output stage has no chance to hold the gate off. I don't realy feel like Mosfet totem pole configuration because of... well shout through. The driver circuit would be way to complicated and delay switching events a ton.How the hell do they get these Class D Amps get to work? I simulated it with real Driver ICs and at certain Q(G) and V(GS)every high side driver IC renders useless.300V in 50ns is the goal...Either you have an Idea, how to convert a Square PushPull Totem Pole BJT signal in to mosfets with pull down to zero volts or whatever else is possible. If you have an Idea, I am totally waiting to here it before I get totally insane!Edit: This is the link to the LT-Spice file so you can take a look at the problem. Just simulate a few tens of microseconds and you will see the shoot through. I don't manage to fix the solution and don't 100% get the problem...http://s000.tinyupload.com/index.php?file_id=99962263409283120830

author: rentner
author_rank: Regular Contributor
timestamp: October 08, 2017, 08:06:45 am
content: Push!Thread got to oblivion and no click in a week!

author: fourtytwo42
author_rank: Super Contributor
timestamp: October 08, 2017, 09:48:31 am
content: First it would be preferable to provide a schematic as a pdf so people can see what you are doing without resorting to downloading a file into LTspiceSecond with no knowledge of your circuit I would suspect the drive impedance of the high side mosfet is to high.

author: capt bullshot
author_rank: Super Contributor
timestamp: October 08, 2017, 09:55:22 am
content: A negative voltage applied to the gate in off-state may help. This is standard with IGBTs, no so common with MOSFETs.Or have a look of some of these optoisolated IGBT drivers from avago, some of them have special miller clamp for this issue.If you use discrete BJTs, look for collector currents in the range of several Amps. Zetex / On make such transistors especially for gate driver purpose. Smaller transistors won't work properly here.

author: Circlotron
author_rank: Super Contributor
timestamp: October 08, 2017, 10:00:05 am
content: Quote from: capt bullshot on October 08, 2017, 09:55:22 amThat's what I was going to say too.
ethernet cable tester or something - Page 1
Forum section: electronics / beginners

author: jonsykkel
author_rank: Newbie
timestamp: December 06, 2015, 10:00:22 pm
content: hi, i suck at electronics and im trying to invent an ethernet cable tester. the idea is to have 2 boxes, one active and one passive, each with their own rj45 port. the active box generates 4 different frequencies using a ripple counter or something, mixes them together and sends the resulting signal through the cable pairs (the 4 pairs have their "own" frequency, for example orange pair corresponds to 8kHz, blue one 4kHz and so on). the passive box has bandpass filters across the pairs that filter out the frequencies that dont belong to each pair. not sure if this idea is completely retarded or if it could work. the purpose of having the different frequencies for each pair is to be able to determine if for example 2 pairs are swapped around in one end or something. anyway i have a couple of questions:1. would the passive filtering thing work at all? could i just use simple RC filters? maybe the fact that the frequencies are harmonically related would mess things up, i dont know.2. in the active box, how could i detect if a frequency is present?here is a picture that might help explain (drew only 2 pairs of the pairs)thanks in advance

author: Ian.M
author_rank: Super Contributor
timestamp: December 07, 2015, 12:08:11 am
content: A good ethernet cable tester will detect opens, shorts, and *ANY* miswiring including swapped pairs, inverted pairs, split pairs etc.A great ethernet cable tester uses +/-1V signal levels so it wont damage the transceiver of a connected device if it is accidentally connected to an active cable, and tolerates +/-50V on all pins so it isn't harmed if accidentally connected to a POE feed.Then you get into cable identifiers . . . .

author: jonsykkel
author_rank: Newbie
timestamp: December 07, 2015, 05:18:07 am
content: Quote from: Ian.M on December 07, 2015, 12:08:11 amgood points, thanks for the replyi think it should handle opens, swapped pairs and split pairs already, shorts could be detected by testing one pair at a time and seeing if the signal appears on any other lead, and for inverted pairs i think i could just place a diode in the passive box.i dont know how one would protect from +-50v, i think its not really that important as im just doing this for fun and to learn. though it would be nice to know how that theoretically could be done.

author: Ian.M
author_rank: Super Contributor
timestamp: December 07, 2015, 05:51:57 am
content: Quote from: jonsykkel on December 07, 2015, 05:18:07 amThat's relatively easy. One approach would be to put a30mA polyfuse rated at >50Vin each line at each end, with heavy duty Schottky clamping diodes to a positive and a negative clamping rail at each end and a 1N5335B 3.9V 5W Zener between the clamping rails. That would limit the max voltage between any two pins to 5V.Another cheaper approach would be to put a 10K 1/4W resistor in series with each line at each end, but that would make it impossible to detect excessive resistance at the RJ45 plug terminal crimp or the socket punchdown.
"Learning the Art of Electronics" - Page 1
Forum section: electronics / beginners

author: jobog
author_rank: Regular Contributor
timestamp: February 12, 2016, 07:36:13 pm
content: I was going to buy "The Art of Electronics" from Amazon when this book, "Learning the Art of Electronics" came up in the search. Same authors, the cover looks the same. They are taking pre-orders as the book is not yet released. Does anyone know if this is legitimate or is it a ripoff copy of the original? It appears to be more lab oriented than the original. I am questioning the legitimacy as there are several grammatical errors evident when reading through the preview.

author: Pack34
author_rank: Frequent Contributor
timestamp: February 12, 2016, 07:46:06 pm
content: It's a companion book. The previous edition had the same thing.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: February 12, 2016, 10:18:51 pm
content: I have the previous edition.It is a very good book, with lab exercises on concrete electronics, with a lot of tutorial.As for the main book, its the best of its kind.

author: Audioguru
author_rank: Super Contributor
timestamp: February 13, 2016, 12:09:16 am
content: I got my copy online for free 10 years ago.

author: JoeN
author_rank: Frequent Contributor
timestamp: February 13, 2016, 01:25:23 am
content: Quote from: Pack34 on February 12, 2016, 07:46:06 pmI'd rather have the X chapters done.

author: Zero999
author_rank: Super Contributor
timestamp: February 13, 2016, 09:55:13 pm
content: Quote from: Audioguru on February 13, 2016, 12:09:16 amI wasn't aware they were officially giving it away.I know a few years ago, there various some sites where pirate copies could be downloaded.
"pure" sine wave inverters (sunforce pro series in particular) - Page 1
Forum section: electronics / beginners

author: kyedo2002
author_rank: Newbie
timestamp: May 24, 2013, 09:00:57 pm
content: I wanted to know if since a/c inverters list a peak and a continous output if you could "hack" the inverter by specifically cooling components because I imagine the peak period is short because the inverter simply can't(doesn't for marketing reasons) have this extra feature.

author: Paul Price
author_rank: Super Contributor
timestamp: May 24, 2013, 11:31:15 pm
content: Get a fan, the only difference between a hot convertor that gives you the current your want and a cold one that does is cooling.
"seeing" sound recorded on video? - Page 1
Forum section: electronics / beginners

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: August 23, 2015, 10:36:16 am
content: Assuming I can link to this public video on facebook...What causes the camera to show the "shock wave" at about 11 seconds?Someone suggested the lense in the camera flexing, or the camera sensor moving, but then why wouldn't it continue to happen throughout the video?

author: German_EE
author_rank: Super Contributor
timestamp: August 23, 2015, 03:54:44 pm
content: A couple of guesses:1) The air is being severely compressed and forms a lensing effect.2) The sound level affects one or more sensors in the camera.I don't think it's the camera lens flexing because a) these are made of glass or hard plastic and b) this would affect the focus. In any event I hope that whoever was holding the camera was wearing earplugs.

author: unitedatoms
author_rank: Frequent Contributor
timestamp: August 23, 2015, 04:07:24 pm
content: What causes the camera to show the "shock wave" at about 11 seconds?Someone suggested the lense in the camera flexing, or the camera sensor moving, but then why wouldn't it continue to happen throughout the video?It could be difference in grip force of human operator's hand. Humans body mechanics is adaptive filter, so it behaves differently after 11 sec.

author: Balaur
author_rank: Unknown
timestamp: August 23, 2015, 04:11:16 pm
content: IMHO the explanation is much more mundane: the operator hands were hit by the initial sound wave and that caused the phone to move/tilt/rotate crazy. Since that was the first big bass, the operator wasn't quite prepared. Afterwards, consciously or not, he stabilized the phone better.EDIT: I agree with unitedatoms, haven't seen his reply before answering.

author: codeboy2k
author_rank: Super Contributor
timestamp: August 24, 2015, 04:29:40 am
content: I was watching the sun-visors shake up and down and wondering what his ear drums and microscopic little tiny small eensy fragile irreplacable inner ear bones must be doing right about then...
"Side channel" information on laptop audio jack? - Page 1
Forum section: electronics / beginners

author: keystroke
author_rank: Newbie
timestamp: December 15, 2012, 07:14:50 am
content: I'm playing around with an oscilloscope and my laptop's headphone jack. I get the tip/ring/ground and measure between them. I also measure between them and an external reference ground. I notice I can see when the battery is charging. That is, if the battery is not in the laptop but the AC is in, then I insert the battery, it runs through a few seconds of a test, and then if the battery is not full, it goes to a certain waveform – if it is full, it goes to another "quieter" waveform. This is best done when the laptop is turned off otherwise the waveform is quite noisy.I'd like to be able to understand more about what is going on. Might there be any other data present in the signal on the headphone jack if I am not putting out an audio waveform? ie. by virtue of the circuit passing through some of the data processing elements of the motherboard, when the computer is powered on? There is a lot of noise in the signal but maybe it is possible to clean it up some.I thought this was interesting as it is a similar idea:http://cs.tau.ac.il/~tromer/acoustic/(Here the noise comes from a bank of 1500µF capacitors).Thanks everyone!

author: Rerouter
author_rank: Super Contributor
timestamp: December 15, 2012, 07:51:11 am
content: its either radiated noise off the switchmode charging circuit or electrical noise on the supplies and final signals of your laptops amp / dac, its not too uncommon, just depends on what its amplitude is compared to say a quiet piece of music, if its 1/10th or less, you probably wont consciously notice it, (expecially if a constant tone)

author: T4P
author_rank: Super Contributor
timestamp: December 15, 2012, 08:36:04 am
content: Is your laptop PSU isolated? Because if it is then PSU noise will couple into the laptopOR if it's non-isolated but it doesn't have a third-prong and usually that third prong is used to couple some noise onto the earth pinOr it could be that your PSU is non-isolated has a third prong but there's a ground loop usually with UK plugs i defeat ground loops by reversing the plug ( if you could, some PSUs might blow up)
'Zigzag' pin header - Page 1
Forum section: electronics / beginners

author: namlu
author_rank: Contributor
timestamp: August 26, 2014, 10:12:37 am
content: Hello.I came across this pin header.Any idea how it is called? What do I write on eBay / anywhere else in order to find this.Thank you.Sent from my iPhone using Tapatalk

author: bobcat
author_rank: Regular Contributor
timestamp: August 26, 2014, 10:38:05 am
content: Offset pin header?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 26, 2014, 10:43:36 am
content: Probably a custom part, or a standard long header that's been formed

author: German_EE
author_rank: Super Contributor
timestamp: August 26, 2014, 12:30:44 pm
content: I think it is to convert from 0,3 inch spacing to 0,6 inch. No idea what they are called though.
A!tium Designer - Page 1
Forum section: electronics / beginners

author: Lunat1c
author_rank: Contributor
timestamp: March 13, 2011, 07:54:30 am
content: Hi,Recently I had the chance to try out A!tium Designer and I must admit I found it quite nice to work with. However I realized that during the simulation process neither currents nor voltages can be measured by means of a probe (voltages can only be seen in waveforms, while I don't have a clue how to measure currents). Am I missing something obvious here?

author: Hypernova
author_rank: Unknown
timestamp: March 15, 2011, 02:06:57 pm
content: Wow, you are the first person I know who actually use the simulation part of it. Everyone I know just use it for the PCB design.

author: neoone
author_rank: Regular Contributor
timestamp: March 20, 2011, 01:46:25 am
content: hmm I must admit that it's true that almost no one I know uses Altium as simulation soft even though it is a part of the CAD course on University. Any way as I remember it is similar to PSpice, maybe I'll check that if I have time.

author: EEVblog
author_rank: Unknown
timestamp: March 20, 2011, 01:58:00 am
content: Quote from: Hypernova on March 15, 2011, 02:06:57 pmWhat can I say other than ditto :->Dave.

author: reagle
author_rank: Unknown
timestamp: March 20, 2011, 06:54:02 pm
content: I dunno, the post-layout simulation features are nice, though I am still only planning to use themThinking it may come handy to tweak termination resistors on high speed memory buses for example

author: RayJones
author_rank: Frequent Contributor
timestamp: March 20, 2011, 07:14:48 pm
content: Oh for a bare bones / bare price version.Sounds like we are all paying a lot extra for fluff only a minority use!
a) New member; b) is there any "copper ink" for the creation of PCBs ? - Page 1
Forum section: electronics / beginners

author: PCBaby
author_rank: Contributor
timestamp: December 08, 2015, 08:36:35 pm
content: Greetings. I'm new to this forum ...and to basic electronics also. Thanks in advance for your patience, then :-)My first question is probably quite naïve, but I didn't find the answer yet: I always saw that we create PCBs by way of erasing (and wasting) the part of the copper layer we don't use ...instead of just writing the lines we do. Are there 3D printers e.g. (or normal printers for that matter) that can spit the final product using "copper ink" ?

author: naragon1
author_rank: Contributor
timestamp: December 08, 2015, 08:45:40 pm
content: Welcome. There are several "solutions" like this out in the market. The Amp Hour Podcast did an episode on this type of solution - I believe it was #260.http://cartesianco.com/http://voltera.io/http://www.voxel8.co/https://www.kickstarter.com/projects/1597902824/agic-print-printing-circuit-boards-with-home-printHaven't used any of them ... so I can't provide feedback or recommendation on any specific one.

author: PCBaby
author_rank: Contributor
timestamp: December 09, 2015, 08:41:09 pm
content: @Naragon.Many thanks for your answer! Those are interesting solutions indeed, although quite expensive ones. "Cost the skin of the butts", as we say hereI saw that one of the problems seems to be that the conductivity of the ink is not as good as copper's, and even seems to worsen with time. One thing I'll try, then (provided I can find indelible ink) would be to reinforce the lines written by the printer with simplecopper-to-PCB electrolysis. This will (hopefully) create an additional layer providing better conductivity.A beginner's dream, probablybut I'd like to give it a try if I find the necessary ingredients.Temporary bridges would obviously have to be inserted between the various lines in order to expose all to the electrolysis etc.etc.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: December 09, 2015, 10:35:58 pm
content: pro pcb fabs use various combinations of additive processes and/or very thin Cu foil, build up full copper trace by electrolysisbut there are some places roll annealed Cu foil is superior and big pcb places will be recycling the etched Cufor small, simple home fab the foil already laminated to the glass-epoxy is easy to work withbut given the time, trial and error, special equipment, space required to become a "home pcb fab hobbyist" and home chemical waste disposal headachesI highly recommend 1st world hobbyists to send out to the many low volume/quickturn pcb fab services that exist - get a pro product, plated thru holes, and have an expectation that environmental regs are followed
A (hopefully) not so beginning question on S-parameters - Page 1
Forum section: electronics / beginners

author: hpmaxim
author_rank: Regular Contributor
timestamp: April 28, 2022, 12:33:41 am
content: I am struggling to understand scattering parameters in the context of nodal analysis. As I understand it, Sxy describes the ratio of voltage coming out of port x vs the voltage going into port y. As an amateur radio operator, I'm quite familiar with the notion that power entering one end of a transmission line could be reflected (S11), attenuated (S21) or amplified (if S11+S21 > 1). And I realize that motors can produce "back emf" which can simply treated as a series voltage source...But I have trouble wrapping my mind around the concept of directional flow of voltage when it comes to say a nodal analysis as you would encounter when running SPICE in transient mode. In fact, SPICE is notoriously bad at supporting S-parameters. As it stands, S-parameters aren't a natural fit. S-parameters are specified as a function of frequency and there is no concept of frequency in a transient analysis. However, we aren't helpless here, we can perform an inverse FFT and get an impulse response (mind you, that impulse response is unlikely to be perfect for a variety of reasons), and then we can perform convolution... So given S21 and a voltage on port 1, we can calculate the voltage on port 2 in the time domain.But this leaves a few questions in my mind:1) What of S11? The model I proposed of the transmission line essentially treats Port 2 as being a voltage controlled voltage source with no loading on Port 1 -- in reality, the transmission line should impact current distributions and hence voltages on Port 1 -- which in turn would impact Port 2. Perhaps this secondary impact on port 2 would be considered a reflection and already taken into account in S21 -- but I'm not clear it accounts for how loading on port 1 may affect the signal coming into port 1, particularly if the input signal is being driven by a non-linear element like a transistor.2) What of S12? If the voltage on port 2 is a voltage controlled voltage source, then what happens if someone is putting a signal into port 2. You can't really parallelize voltage sources.Thanks in advance for all the thoughtful answers to follow!

author: m k
author_rank: Super Contributor
timestamp: May 01, 2022, 01:10:38 pm
content: I don't understand what you don't understand.Maybe you're just missing a correct picture.If there is a galvanic connection S2 is obviously affecting S1.It's just a perspective of analyze where it is not.If you have a transmitter and a receiver, and you measure their antenna connections you get a practical spectral response and that's it.It's irrelevant why it is what it is, it still is.What changes if you change antennas to wire connection?You mentioned a time domain, does it have a size?Fastest speed is finite so even smallest parts feel the difference.Parallel voltages have combined energy.I think you would get better answers from different section of the forum.
A "Click" with a piezo - Page 1
Forum section: electronics / beginners

author: brue
author_rank: Contributor
timestamp: October 15, 2012, 06:04:20 pm
content: HiIm designing a product that uses capacitive sensor buttons. For better usebility, i would like to have a "click" sound if a button press is detected.I do not have much space for a loudspeaker, so i want to use a piezo.But how do i produce a nice sound like a click with a piezo? Is it possible at all?I dont want only a crappy biiiip.Thanks

author: AndyC_772
author_rank: Super Contributor
timestamp: October 15, 2012, 06:09:50 pm
content: I'd have thought that was the easiest sound of all!Why not test it out? I presume you're using a microcontroller of some kind, so get hold of a sample of a piezo transducer that you can accommodate within your product, and connect it to a spare I/O pin (maybe via a transistor to buffer it).Experiment with a few different drive waveforms - start with a single logic high pulse 1ms wide, then vary the pulse width and the number of pulses in the burst until you get a sound you like.

author: ejeffrey
author_rank: Super Contributor
timestamp: October 15, 2012, 08:42:58 pm
content: A step impulse or a single pulse of several ms will usually generate an acceptable click sound, but it may be a bit quiet depending on the size of the piezo element and the environment. To make it louder you need several pulses, but then it starts to sound more like a beep.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 15, 2012, 10:33:30 pm
content: For the best volume, give it a few cycle at its resonant frequency - a very short beep will sound louder than a simple click.
a alternative for a MAX744A chip????? - Page 1
Forum section: electronics / beginners

author: pol
author_rank: Newbie
timestamp: January 06, 2012, 12:00:50 am
content: first I want to say sorry for my English, I know its not so good.But does anyone have a good alternative for a MAX744A chip.The damn thing is not available any more here in Holland.(its a 5V, Step-Down, Current-Mode DC-DC Converter.)Thanks,
A better soldering iron - Page 1
Forum section: electronics / beginners

author: Vaati
author_rank: Newbie
timestamp: August 02, 2011, 02:18:59 pm
content: I've done some searching for a better soldering iron than the one I've been using for the past 3 years, a WP25. A few days ago I watched a video on drag soldering, and realized that having a 30 year old iron (without even knowing the necessity of flux I might add) might not be ideal for such a method.So far, it looks like I ought to go with the Atten 937B or the 938D -- does anyone have either of these irons? If so, please write a review/post a teardown.Thanks.

author: saturation
author_rank: Super Contributor
timestamp: August 02, 2011, 02:36:39 pm
content: Atten as a brand is very mix quality at best, doesn't work at worst. If you are going to buy a Chinese branded station, Aoyue is a better bet.A best bang for buck right now is the Hakko FX 888 or the Weller WES51.

author: hodx
author_rank: Newbie
timestamp: August 09, 2011, 11:26:29 pm
content: Ditto on the Hakko FX 888...its the best bang for your buck.....best $95 i ever spent.............

author: CoolBeer
author_rank: Newbie
timestamp: August 10, 2011, 12:20:48 pm
content: I agree on the fx-888, it's a whole nother world from my previous ebay iron.And if you look at it as an expensive tool, it will definitly last you a long time, so per year it's nothing at all-Kolbjørn
A bit help with identifying Fault...   (Stroboscope 12000 F/min) - Page 1
Forum section: electronics / beginners

author: Haltec
author_rank: Newbie
timestamp: January 26, 2014, 06:05:47 pm
content: Can someone please help with identifying this CDM element ?It's a UNILUX Lith-O-Light 5 Strobe. An schematic would be great / on PM off course.It use do deviate in flash timing *few flashes per min - and after inspection re-assembly it doesn't flash at all... - Regardless of timer setting.FET's are replaced and working.Kind thanksBR

author: Andy Watson
author_rank: Super Contributor
timestamp: January 26, 2014, 06:49:22 pm
content: Quote from: Haltec on January 26, 2014, 06:05:47 pmAlmost certainly a capacitor used to store the main charge for each flash. Looks like it has been specially made to fit - hence the unilux code.12000 F/m is a very high rate, if this unit has been used at that rate for any significant time I would consider the possibility of the flash tube being tired - they are only good for a limited amount of energy.

author: Haltec
author_rank: Newbie
timestamp: January 26, 2014, 07:21:39 pm
content: Tube is NEW. (208 usd goes off....)Sorry I didn't mentioned earlier.Is there any reasonable way to determine state of that capacitor or even it's capacitance (claculation??) since is "custom built" for this app. ?Agreed 100% about high rate. And it works almost 24/7 in printing business.(It make pictures on high speed passing "endless" paper look's still so that color aligment can be visually inspected... / each of four colours are placed separately on anilox rollers - sometimes few metars away from each other....)Kind thanks for your reply.Haltec

author: SeanB
author_rank: Super Contributor
timestamp: January 26, 2014, 07:33:19 pm
content: At a quick ballpark looking at the size it will be around 1-2uF at about 400VDC rating. Not likely to have failed but unsolder one end and check the capacitance. If it has high voltage on it when powered ( usual caveats apply about probes and shorting out traces etc and safety) it will have around 300-400V across it. If it is there look at the trigger side. If not look at the inverter side or the inverter regulation loop.

author: Andy Watson
author_rank: Super Contributor
timestamp: January 26, 2014, 07:56:15 pm
content: I agree, something of the order of 1uF, several hundred volts. As SeanB says - unsolder it and measure it. The writing under the ty-wrap might give you some more info on the size. Since this is most likely a special you'll have to go back to Unilux to get it - so probably worth emailing them and asking/begging for details so that you can test it properly.Just had a squint at the Unilux webstie - ouch! These people know how to charge!

author: Haltec
author_rank: Newbie
timestamp: January 28, 2014, 06:08:59 pm
content: Several thousand volts maybe ?http://www.talonix.com/shop/item.aspx?itemid=8858#.Uufw2_s1hkgHow to test this one I have anyway ?Yes - they doing great job regarding charging. Schematics are around 100 usd (officially from Unilux)Kind thanks for your replys.Haltec
A.C. applied to a coil's centre-tap - Page 1
Forum section: electronics / beginners

author: Quantumplate
author_rank: Regular Contributor
timestamp: September 14, 2023, 02:32:00 pm
content: I found a circuit for a part of a radio called a 'double balanced mixer' that featured a signal applied to the secondary's centre tap. The author said when it swings positive both ends of the coil also swing positive.Now that is the opposite of a single coil affair. (no tap, signal in at one end)Is the reason because: in the centre-tapped coil we effectively have two coils in parallel, but as they are wrapped on the same core then the magnetic fields cancel each other out resulting in no inductive effects?I've searched on this, but in vain. Radios...pah! old hat...

author: TimFox
author_rank: Super Contributor
timestamp: September 14, 2023, 04:21:32 pm
content: Yes, double-balanced mixers can be made with two transformers (each with a center-tapped secondary) and four diodes.Seehttps://blog.minicircuits.com/a-quick-guide-to-mixer-topologies/The "RF" (input) and "LO" (oscillator) are applied "normally" to the two transformer primaries, producing a voltage across the secondary of each.The "IF" (output) is taken between the two secondaries' center taps, typically grounding one of them, and is DC coupled.

author: jwet
author_rank: Frequent Contributor
timestamp: September 14, 2023, 04:22:00 pm
content: This is correct. It might help to think first about the DC case. If you change the DC of the center tap, both ends will follow it up and down one to one. Its like biasing circuits. AC really doesn't change anything.You've just gotten to the beginning of a long trek to understand mixers and double balanced ones especially. There a lot of Hams and even EE's that never fully appreciate the magic how these work. Lots of resources on the Web. A of E and ARRL Handbooks have lucid explanations.Good Luck.

author: Quantumplate
author_rank: Regular Contributor
timestamp: September 14, 2023, 07:53:25 pm
content: Quote from: jwet on September 14, 2023, 04:22:00 pmHi John! Thanks, but the thing i need to understand is why? Is my explanation correct or no?

author: langwadt
author_rank: Super Contributor
timestamp: September 14, 2023, 08:13:20 pm
content: Quote from: Quantumplate on September 14, 2023, 07:53:25 pmthe coils and inductance is not really involved, you are just moving everything up and down

author: Quantumplate
author_rank: Regular Contributor
timestamp: September 14, 2023, 08:50:51 pm
content: Quote from: langwadt on September 14, 2023, 08:13:20 pm

author: ledtester
author_rank: Super Contributor
timestamp: September 18, 2023, 01:02:06 am
content: Quote from: Quantumplate on September 14, 2023, 02:32:00 pmThis video on the workings of a (double-balanced) diode-ring mixer might be of interest:#167: How a Diode Ring Mixer works | Mixer operation theory and measurement -- w2aewhttps://youtu.be/junuEwmQVQ8
A capacitor of 5mF is ok for this type of circuit? - Page 1
Forum section: electronics / beginners

author: bonzer
author_rank: Regular Contributor
timestamp: January 05, 2019, 10:47:49 pm
content: Hello everyone! Please tell me if you think this is a bad idea. Having a circuit like this with resistors of value about 10kOhm and the second capacitor 300nF. It feels like that 5mF capacitor is too big but I don't know. For that frequency of operation, do they even exist non electrolytic or non polar like ceramic with good frequency response? Would they cost too much? Is this anyway possible? I don't have to implement it practically but anyway I would like to know what are the disadvantages, a part from maybe big dimensions. If it's a huge problem I could anyway solve it by changing some resistor values but please let me know what you think.

author: Zero999
author_rank: Super Contributor
timestamp: January 05, 2019, 10:58:28 pm
content: 10kHz is not a high frequency.Presumably you mean 0.005F, by 5mF, not 5µF.Why not make it DC coupled? 5mF and 10k is a time constant of 50s, so it will take around 10 minutes for the DC bias point to be reached.

author: bonzer
author_rank: Regular Contributor
timestamp: January 05, 2019, 11:18:41 pm
content: Oh thanks! I didn't think about it. So it's also a problem in DC.

author: M4trix
author_rank: Frequent Contributor
timestamp: January 05, 2019, 11:30:10 pm
content: Good luck finding a 5µF capacitor.

author: Audioguru
author_rank: Super Contributor
timestamp: January 05, 2019, 11:35:32 pm
content: 5mF is 5 milli Farads which is 5000 micro Farads that is HUGE! A 1uF film capacitor will produce a -3dB cutoff frequency at 16Hz.Why do you want a peak of more than 10000 times at about 15kHz? When the input is only 5mV peak which is almost nothing then the output will try to be more than 50V peak.Here is a simulation with a 1uF input capacitor:

author: Zero999
author_rank: Super Contributor
timestamp: January 06, 2019, 08:52:41 am
content: Quote from: M4trix on January 05, 2019, 11:30:10 pmUse the nearest E6 value, which is 4.7µF or if non-polarised is really required, two 10µF back-to-back.I didn't mention this in my previous post, because I'm not convinced a non-polarised capacitor is necessary.

author: bonzer
author_rank: Regular Contributor
timestamp: January 06, 2019, 02:57:19 pm
content: Thanks for your answers. Well you convinced me that it's not the case. I will try to change some resistors. I also noticed later that it anyway doesn't do what I was looking for (it introduced me the first zero at higher frequency while I wanted the first zero to be in the origin.)
A capacitor question, ceramic versus film. - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: May 07, 2019, 09:43:44 pm
content: In the attached circuit C1 and C2 are 470pF for the MF version. I built the LF version and used polypropylene caps, easily found in 1nF value. I am building the MF version now, and I do not have poly caps in 470pF, is there any reason not to use ceramic through hole caps there, at 470pF? Thanks.

author: jmelson
author_rank: Super Contributor
timestamp: May 07, 2019, 10:34:06 pm
content: Just use NP0 caps, and it should be fine. Most likely anything at all will also be fine, is is just 5 V signals, anyway.Jon

author: David Hess
author_rank: Super Contributor
timestamp: May 08, 2019, 03:00:28 am
content: In almost all cases, ceramic C0G/NP0 capacitors can be used in place of film capacitors. In many cases including this one, ceramic X7R capacitors (10% tolerance) would also work.

author: pwlps
author_rank: Frequent Contributor
timestamp: May 08, 2019, 08:42:57 am
content: Poly caps are much more stable (temperature, aging) than the ceramic ones so you would use them e.g. in an RC or LC oscillator, but I don't see any reason to not to replace them with ceramic caps here.I have a question: in your circuit the high and low side mosfets are driven in quadrature (from the 7474), what is the purpose of that?

author: Chris Wilson
author_rank: Super Contributor
timestamp: May 08, 2019, 10:16:21 am
content: Thanks for the replies, I guessed the ceramics would be OK as coupling caps in this application but thought it prudent to check and be sure, I know now for next time, and I much appreciate all the help

author: Chris Wilson
author_rank: Super Contributor
timestamp: May 08, 2019, 10:20:28 am
content: Quote from: pwlps on May 08, 2019, 08:42:57 amI am not able to answer that, I am a relatively novice builder of it, not the designer, but if it's relevant and helps, the signal applied to the input is X2 the wanted frequency and the circuit divides by two and the output is half the input, Class D. All similar amps for LF and MF amateur bands usage seem to use the same topology. Sorry, I am not sure that really answers your questionThank you for the info re the capacitors.
A cheap way to compare DC microamp readings in multimeters. - Page 1
Forum section: electronics / beginners

author: camurgo
author_rank: Newbie
timestamp: November 08, 2018, 10:53:10 pm
content: Hi everyone,I would like compare the accuracy of the readings of my multimeters in the DC microamp range. I would also like to accomplish this in the cheapest way possible.To carry this out I assume I need some sort of adjustable electronic load (I have of one these,https://www.aliexpress.com/item/ATORCH-150W-Constant-Current-Electronic-Load-200V20A-Battery-Tester-Discharge-Capacity-Tester-meter-12V24V48V-Lead-acid/32821877897.html?spm=a2g0s.9042311.0.0.78854c4dKUizpXand it works fine for the amp range) or current source, but I couldn't find one so far that goes below the miliamp range.Does anyone have tips/suggestions to achieve this? Thanks.

author: ArthurDent
author_rank: Super Contributor
timestamp: November 08, 2018, 11:34:27 pm
content: You can compare one meter against the other to see how closely they agree but that tells you next to nothing about the accuracy of the meters, unless one is of known high accuracy. Also an electronic load like you've shown probably isn't that useful, especially for low level currents.If you had a known accurate power supply voltage with a known accurate resistor you could check the known current accuracy of your meters. Without knowing 2 of the variables in the equation E=IR you can't accurately calculate the third. Also the R in the equation is the known accurate resistor plus the meter resistance.

author: 6PTsocket
author_rank: Regular Contributor
timestamp: November 08, 2018, 11:43:00 pm
content: Quote from: camurgo on November 08, 2018, 10:53:10 pmWhat is your reference standard? If it is an accurate microammeter, put the meters in series, adjust current for mid scale and full scale readings on the reference meter and compare. If it is an accurate voltmeter, buy a resistor to the accuracy you require and mesure voltage drop across the resistor. Ohms law will take it from there. Select values that will be on the upper part of the ammeter range. Linearity is a factor. Meters can be dead on at one part of the range and off in another. There is no need for some super accurate source, as long as it is adjustable to get your meters to read on scale. Remember, these are microammeters so keep current limiting in mind.Sent from my SM-G900V using Tapatalk
A Chinese alternative to TPS6300X Single Inductor Buck-Boost Conve - Page 1
Forum section: electronics / beginners

author: anda3243
author_rank: Contributor
timestamp: April 02, 2022, 04:25:59 am
content: Hello EveryoneI am working on a design where I need a power supply for a CSK32F103 processor (this is a STM32F103 clone that is available in China).Originally I was thinking to use the TPS6300 from Texas instruments, but these are not available in china. Almost same prices as gold for this component in China. The trade war and chip shortage is felt in China.This component is a bit overkill, it provides a more power than I need, but it has a convenient low power mode that is good to preserve the battery.Component info:https://www.ti.com/lit/ds/symlink/tps63001.pdf?ts=1648872896497&ref_url=https%253A%252F%252Fduckduckgo.com%252FPower save feature is mentioned in chapter 7.4.3 on page 9.The best replacement I have found so far is something like this:https://item.szlcsc.com/236244.htmlIts a much simpler component. But it does not have the low power mode.Does anyone have a suggestion for a component, or a circuit that can be made with lower end components?Thank you in advance!

author: amyk
author_rank: Super Contributor
timestamp: April 02, 2022, 07:12:38 am
content: What's your Vin and Iout/Vout requirements? The TPS6300X is a buck-boost but the ME2108 is a boost only.HX8001looks like a very close match.

author: anda3243
author_rank: Contributor
timestamp: April 02, 2022, 07:44:56 am
content: Quote from: amyk on April 02, 2022, 07:12:38 amThank you for the answer, I will check it out.The input voltage can be 2.7 to 5.5 V. The output should be 3.3 V .
A chip for smooth dead time adjustment - Page 1
Forum section: electronics / beginners

author: AlexRG
author_rank: Regular Contributor
timestamp: April 15, 2025, 09:23:03 pm
content: Hello friends! I'm looking for a chip that could smoothly adjust the dead time. I drew an approximate diagram.What is required:- power supply +5V- 3.5MHz PWM input (if more, only better)- two outputs, direct and inverted- load 15-20pf- there must be a pin for connecting a resistor. This resistor needs to adjust the dead time from 10 to 100 ns. If wider, only better. But, not lower than 10-15 ns.And most importantly, it is very desirable to have a body that has legs. That is, SO, SOP, SOIC, SOT23, etc. BGA mounting and blow dryer I can not pull..For example and understanding. The dead time adjustment mechanism using just one resistor is implemented in many drivers, for example NCP51561, UCC21530. Shouldn't there be a simple microcircuit for weak signals?) Please help me find one.