hybridfree/eevblog-posts huggingface dataset:
SPDT output voltage for unconnected input - Page 1
Forum section: electronics / beginners

author: crazymach
author_rank: Newbie
timestamp: March 02, 2018, 09:50:54 pm
content: Noob question.If I had a 2:1 multiplexer like this onehttps://assets.nexperia.com/documents/data-sheet/74LVC1G3157.pdfInput 1 was a normal signal going through it, and input 2 was disconnected and I selected input 2, will the output be connected to input 2, thus be an open? And will this output have a voltage related to the VCC or GND rails?

author: David Chamberlain
author_rank: Frequent Contributor
timestamp: March 03, 2018, 08:25:55 am
content: Hi Crazymach, do you mind if I rephrase your question....You are asking if you had a AC signal on Y0 and Y1 was disconnected then what would be the cross talk between Y0 and Z if S were HIGH (meaning Z is connected to Y1)In that case this is given as ?iso "isolation (OFF-state)" on page 13. Figure 22 on page 14 show the test setup for that.But just based on your question the potential of the output (Z) with respect to VCC or GND then technically it should be zero (or at least floating with respect to those rails). This is an analog switch not a digital buffer and so they behave more like a 'solid-state relay' some more info can be found in the link below.https://www.analogictips.com/whats-difference-analog-switch-digital-switch-ics/

author: SebG
author_rank: Regular Contributor
timestamp: March 03, 2018, 08:28:31 am
content: HiThe mux is an analog switch so it acts same as a mechanical toggle switch but with some resistance (~6 Ohms). So if you select input 2 then the output will be floating. Each switch is essentially bidirectional pass-through mosfet that is enabled or disabled using S input.

author: Ian.M
author_rank: Super Contributor
timestamp: March 03, 2018, 09:00:58 am
content: There's a little leakage current - up to a maximum of 2uA so a high impedance voltmeter will measure a voltage between VCC and GND on its output, with a source impedance >500K. The typical leakage is 0.1uA, but that should still be detectable on a 10MegDMM. Don't count on the typical leakage - it will get much worse at elevated temperatures.
Speaker amplifier output with vs without coupling cap ? - Page 1
Forum section: electronics / beginners

author: BravoV
author_rank: Super Contributor
timestamp: September 04, 2013, 06:31:57 am
content: Ok, I understand cap can not pass DC (AC only), thats it, but this is really a noob question, what is the pro & con on each with/without the cap for driving a speaker ?Is it for cheaper cost by reducing just one cap ? I'm "assuming" its not just that simple right ?TIA

author: David_AVD
author_rank: Super Contributor
timestamp: September 04, 2013, 06:40:13 am
content: An amplifier with a single supply rail usually has the output biased at half the supply with no signal. Your audio signal then moves this voltage up (towards V+) and down (towards 0V). The output capacitor removes the DC offset so the speaker only sees the AC (audio) portion.An amplifier with split (+/-) rails has the output near 0V with no signal. Your audio signal then moves this voltage up (towards V+) and down (towards V-). You don't need the output capacitor in this case as there is no DC potential across the speaker.Make sense?EDIT: There are also other amplifier topologies (bridge, etc) that work differently. I've kept it simple for this reply.

author: Tube_Dude
author_rank: Regular Contributor
timestamp: September 04, 2013, 06:38:06 pm
content: Quote from: BravoV on September 04, 2013, 06:31:57 amWith cap- Pro: No need of output protection. In case of short of the output devices, no DC current at the output to burn your speakers.Con: Reduced damping factor at low Audio frequencies and inherent phase shift.Without cap- Precisely the oposite. Need output protection (relay). And no reduction of DF, nor introduction of phase shift at the lower end of the audio spectrum.
Speaker magnet and coil geometry how it works - Page 1
Forum section: electronics / beginners

author: Mike Jung
author_rank: Contributor
timestamp: April 15, 2021, 07:36:19 am
content: I am trying to understand how a speaker REALLY works and in particular the reason for the geometry of the magnet and coil. I do not understand why they are shaped like that and how the coil repels / attracts the concentric magnets.I wonder if somebody knows an explanation on the Web or maybe some book where this is discussed more in depth than the elementary way in most electrical texts.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 15, 2021, 07:55:09 am
content: The round coil is conventient for production and symetry, so it is the obvious choice. To ease on heat transfer the coil is reltively thin (often just 1 layer or wire). The magent is formed to produce a relatiely homogenous and strong magentic flied at the coil. As an alternative form one could have a relatively long coild that extends beyound the magentic field, so that all the field goes through the coild - this way also gives a linear response (constant force for a given current independent from the position). This is a radial field to have an axial force from the current through the coil.To get the flux to the inside it needs a cetain size inside, so that the coil diameter can not be very small. Some suitable steel plate are usially used to concentrate the magentic flied from the relaticely large area magents at the outside (at least for the classic form with ferrite magents). Often the magent itself is just on the outside with axial magnetization.
speaker protection board help - Page 1
Forum section: electronics / beginners

author: Prime73
author_rank: Regular Contributor
timestamp: January 25, 2014, 07:54:47 pm
content: Hello folks,Got off ebay a speaker protection board kit ( here is a link for these who interested:http://www.aliexpress.com/item/Stereo-Speaker-Protection-Board-DIY-Kit/1505413451.htmlAssembled it as per instructions and schematics, but the relay doesn't work when I feed the board with a signal from my amplifier. Here is the schematic for the kit:I'm trying to understand how this schematic works so I can troubleshoot it. I have access to an analog scope (and basic understanding how to use it). When I feed a signal to point A (B) ( see the above schematic) I don't see anything on Q1's base and nothing at point C. I don't understand how "C2, C3 and Q1, Q2" (C4, C5 and Q3, Q4) part work. I would really appreciate if someone could spend some time and help me out.thanks.

author: SeanB
author_rank: Super Contributor
timestamp: January 25, 2014, 08:18:06 pm
content: Q1, Q2 ( along with Q3,4) form a simple level detector. If the DC signal input is above ( or below) around 1.2V for long enough ( the 2 capacitors form a low pass filter to remove most of the audio signal from the input leaving only the DC component) the transistors turn on. Q1 is a simple common emitter turned on for positive signals over 1V2 typically, and Q2 is a common base so needs a slightly higher negative input to get a similar collector current.At point C you will have a voltage of around 1V2 ( 2 base emitter voltage drops of Q7 and Q8) and when one of Q1-Q4 turns on long enough you will see the voltage drop down below this and the relay will turn off. Q5 Q6 are a basic astable multivibrator, and the diode forces the LED on to show power applied and the relay is on, with it starting to flash when the relay turns off.To test you apply around 3V DC to any of the inputs ( either polarity to test both halves) and this should turn the relay off.

author: Prime73
author_rank: Regular Contributor
timestamp: January 25, 2014, 08:58:08 pm
content: thanks for the explanation, makes sense now. Tried 3V on point A and B. I see about 600mV on bases for Q1 and Q3 however nothing at point C. Replaced Q1 and Q2 with new ones (just to make sure and tested the old ones - they seem ok). Still nothing at point C. What else should I look at?

author: Rerouter
author_rank: Super Contributor
timestamp: January 25, 2014, 11:25:39 pm
content: point C should be at about 1.4V with nothing connected to the inputs, voltage has to be coming out of the LM317 in order for the output to work,on 20V for the V+ it takes about 3 seconds to start functioning,at 11V which seems to be close to the minimum you want it takes about 7 seconds to start functioning,so make sure the LM317 is throwing out a decent voltage,

author: Prime73
author_rank: Regular Contributor
timestamp: January 26, 2014, 12:18:20 am
content: thanks again. replaced Q7 (it appears to be a faulty one) and all seems to be working now. Not sure what happened to Q7 though... Point C is at 1.36V and the relay kicks in at about 3 seconds mark. LM317 outputs 12.8V
Speaker Squeal Help/suggestions required! - Page 1
Forum section: electronics / beginners

author: majestic10110
author_rank: Newbie
timestamp: August 23, 2020, 08:29:26 am
content: Hi Guys,I have an audio amp 8 ohm matched to an 8 ohm speaker. When I connect it to the circuit board I want to work with I get an almighty squeal!When I take audio from the circuit I want to work with and power it from another source it works fine.So I know my issue originates from the positive line out of the circuit board when applied to the audio amp.I also find that the audio amp powers with just the positive connected, I believe it is getting ground from the audio headphone socket.Any help to solve this would be appreciatedThanks

author: Jwillis
author_rank: Super Contributor
timestamp: August 25, 2020, 01:18:20 pm
content: It might help if your describe what the circuit board does you are connecting to the amplifier . A block diagram or even beter a circuit diagram .But if I had to guess I would say you have an impedance issue between the circuit board and amplifier that is causing the amplifier to oscillate . Or there is an attenuation issue that may be over driving the amplifier . Their may also be a DC voltage in the AC signal between the circuit board and amplifier which can cause problems . These are just guesses of course without knowing how and what is connected together .

author: bob91343
author_rank: Super Contributor
timestamp: August 25, 2020, 08:39:54 pm
content: Getting the ground from the headphone socket is asking for problems such as yours. You need to make power supply connections separately from the audio connections, and in the case of audio, need to keep the speaker connections separate from the input connections.
Speaking of inductors and switchers - Page 1
Forum section: electronics / beginners

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 20, 2016, 02:59:44 am
content: Is this of use? Like it? Upvote if you want to see more. This is just a teaser:http://seventransistorlabs.com/Images/Phase_Shift_PWM_Teaser.pdf(The overall objective is as the title says; this is just the first subsection or so. For a beginner level kit, I think it would be unfair not to cover these topics, at least very briefly, before getting into the meat of things. The rest is a work-in-progress.)Tim

author: 10101
author_rank: Contributor
timestamp: June 20, 2016, 04:00:25 am
content: seems great, good learning material

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 21, 2016, 07:58:38 am
content: Dang, so not much interest in this?Tim

author: deephaven
author_rank: Frequent Contributor
timestamp: June 21, 2016, 08:07:22 am
content: Don't be discouraged by the lack of response so far. You only posted a bit over a day ago so it's early days. I think a lot of people would be interested but might not necessarily put a response here. I think, once the word gets out, there will be quite a few people who will be anxiously waiting for the next installment if you're going to 'publish' it that way. I for one will be keen to see further from you.
Spec of a scope: "flatness" - What is it exactly? - Page 1
Forum section: electronics / beginners

author: eTobey
author_rank: Super Contributor
timestamp: May 29, 2024, 09:13:53 am
content: I can not find information about this spec (just lot of mechanical flatness).Anyone can explain or has some links for it?

author: gf
author_rank: Super Contributor
timestamp: May 29, 2024, 09:38:04 am
content: If you mean specs like in the attached screenshot, they refer to the frequency response.

author: pdenisowski
author_rank: Super Contributor
timestamp: May 29, 2024, 10:08:14 am
content: I also assume they mean the frequency response - in this case, how uniform the passband is. I discuss this in one of my videoshttps://youtu.be/FhT8TpuI7ek?t=531

author: eTobey
author_rank: Super Contributor
timestamp: May 29, 2024, 12:52:16 pm
content: I have now made 2 different measurements, which i thought would yield the same result. I run a sweep (5-55Hz), and looked at the maximum amplitudes. Then i made a FFT (1Hz - 500Hz), but from 22Hz to 70 Hz there is a huge bump. What is this?

author: ebastler
author_rank: Super Contributor
timestamp: May 29, 2024, 01:29:18 pm
content: What was the actual signal amplitude you sent to the scope during that sweep? Looks like about 20 mV p-p with a 500 mV offset?!I think you mixed somthing up with the peak hold function. You don't want that applied to the time series signal, but select it as the FFT mode! (So the FFT uses the strongest frequency components it encounters at various times, while the sweep is ongoing.)You also need to set a rather slow sweep time on the signal generator. Essentially the FFT must complete at least one full spectrum calculation for each data point you want in the final swept spectrum.

author: gf
author_rank: Super Contributor
timestamp: May 29, 2024, 02:27:08 pm
content: Quote from: ebastler on May 29, 2024, 01:29:18 pmIndeed. Never ever use peak detect acquisition mode in conjunction with FFT.Peak detect acquisition isnotsampling in the sense of the Shannon-Nyquist samplling theorem.
basic questions - Page 1
Forum section: electronics / beginners

author: newtoCBs
author_rank: Newbie
timestamp: February 26, 2022, 07:50:00 pm
content: Could someone please identify what each of these devices are.Thanks.[ Attachment Invalid Or Does Not Exist ]

author: Swake
author_rank: Frequent Contributor
timestamp: February 26, 2022, 08:22:51 pm
content: a: condensator, polarised. cannot read the value.b: diodec & d & i: condensator.f: unlikely to be resistors, might be coilsg: likely a transistorh: resistors. 333 means 33000 OhmL: probably diode, can be any type of diode. certainly not resistors.grid mazes are just connections, eventually there is a component on the other side of the board.

author: mariush
author_rank: Super Contributor
timestamp: February 26, 2022, 08:56:22 pm
content: A is a tantalum capacitorB are diodes. The code may be printed on the glass bodyC and D are most likely capacitors.F ... agree with Swake, good chance they're inductors.The small rectangles with numbers on them are resistors ... last digit is the number of zeroes for example 101 means 1 zero after 10, so 100 ohm ... in your case 333 = 33000 or 33kOhmI - small ceramic capacitorsE probably a film capacitor otherwise could be an inductor. probably some film capacitor with a very weird capacitance value to get a specific clock or frequency.G could be anything, could be a transistor, could be a mosfet, could be a fixed voltage linear regulator, no idea. Numbers or code on it may tell you more.

author: newtoCBs
author_rank: Newbie
timestamp: February 26, 2022, 09:29:41 pm
content: Thanks.

author: tooki
author_rank: Super Contributor
timestamp: February 27, 2022, 03:55:49 pm
content: Quote from: Swake on February 26, 2022, 08:22:51 pm*capacitors(We used to call them “condensers” in English, but not for a very, very long time. The only place the word survives is in “condenser microphone”.)
Specific Step Down Regulator - Page 1
Forum section: electronics / beginners

author: garagefactory
author_rank: Newbie
timestamp: March 23, 2017, 04:24:20 am
content: Hi everyone I have a question about voltage regulators. I'm trying to design a board for a project that requires 4 different voltages 1v, 1.15v, 3.3v and 5v each line draws approximately 2.25A and I am going to be stepping down to these voltages from a 3400mah li-ion battery at 7.4v. Does anyone have an ic or component they would recommend I use in this type of project thanks for the help!

author: Nusa
author_rank: Super Contributor
timestamp: March 23, 2017, 05:38:00 am
content: Something like this?http://cds.linear.com/docs/en/datasheet/4644fd.pdfIf you meant 2.25A continuous load for each voltage, that battery isn't going to last very long.

author: Rick Law
author_rank: Super Contributor
timestamp: March 23, 2017, 08:59:12 pm
content: 2.25A in 4 voltages makes 9Amps total. Most if not all 18650 protected batteries on the market wont even be able to put out 9Amp.

author: Nusa
author_rank: Super Contributor
timestamp: March 23, 2017, 09:27:38 pm
content: Quote from: Rick Law on March 23, 2017, 08:59:12 pmBzzt, math error! You can't just add amps from different voltages together and get a meaningful result. Convert each load to watts, sum them, then divide by battery voltage to get current draw at the battery. Add a smidge for conversion losses and I get about 3.3 Amps. That's still a lot, but should be within the battery's ability. It just isn't going to last terribly long.

author: mariush
author_rank: Super Contributor
timestamp: March 23, 2017, 09:54:29 pm
content: Maybe a couple of TPS54395PWPR ( 2 x 3A regulators) :http://www.digikey.com/product-detail/en/texas-instruments/TPS54395PWPR/296-30581-6-ND/3478059Yeah, keep in mind that you have 1 x 2.25 + 1.15x2.25 + 3.3 x 2.25 + 5x2.25 = 23.5 watts. Assuming 85% efficiency, you're looking at ~ 27.5 watts or / 7.4v = 3.7A constant load on the battery. This may be a bit too much.Can't you optimize your design so that you won't have 1.0v and 1.15v , couldn't you maybe make them 1.05v or something like that, to use just one regulator but designed for higher current?depending on how much room you have, it may be cheaper to have a stronger 1.15v rail (for 5A+ for example) and use a LDO to get 1.0v @ 2.25A from it. Maybe you're space constrained on the pcb and then the tiny losses (0.15v x 2.25a = 0.33w) would be acceptable. See for exampleISL80103from intersil or MIC59300Linear parts are sexier but expensive and maybe harder to use (in particular the bga or lga parts)

author: Rick Law
author_rank: Super Contributor
timestamp: March 25, 2017, 12:46:24 am
content: Quote from: Nusa on March 23, 2017, 09:27:38 pmNot a math error. My error is, since he is talking voltage regulation, I mind-locked into thinking he was using linear regulator which (unless I am mistaken) takes the same amps in as amps out and just drop the voltage. So, he wants 2.25 amps out, he has to put 2.25 amps in.Of course if he is bucking, than it doesn't need the same amp.
. - Page 1
Forum section: electronics / beginners

author: qwerty1
author_rank: Newbie
timestamp: November 06, 2019, 07:29:30 am
content: .

author: magic
author_rank: Super Contributor
timestamp: November 06, 2019, 07:43:06 am
content: You first need to decide which RGB standard you want to encode in, it's not like there is one. This decision has probably already been made for you by the system that's going to consume your data, whatever it is.Then there is whole science of "color spaces" I'm not very familiar with. But the gist is that human vision has three types of cones with different sensitivity to different frequencies. So you somehow calculate how much each type of cone would be stimulated by the signals you detected and then you construct an equivalent stimulation using the particular RGB colors provided by your display.

author: flynwill
author_rank: Regular Contributor
timestamp: November 06, 2019, 02:47:05 pm
content: It depends on what you mean by "determine color precisely". If the goal is to produce the same appearance to human viewers on a monitor of some sort, then you are looking for a sensor that can sense (or emulate) the CIE color matching functions. You'll then need to apply the appropriate matrix to convert the resulting x,y,Y values these to whatever colorspace your display uses.If your goal is something else then let us know.

author: flynwill
author_rank: Regular Contributor
timestamp: November 07, 2019, 02:30:14 pm
content: Ah, in that case a multi-band sensor like the one you located might work pretty well. But you will likely need to calibrate it with actual test strips. Your color chart reference will have been made with half-toned inks to give the same visual appearance as the actual test strip, but there will likely be significant spectral differences that a multichannel sensor will see differently. The manufacturer of the test strips might have actual spectral response data on the dyes in the test strip that could also be the basis for working out a proper calibration process. if your project has significant backing then the purchase of a real spectral-photometer might be in order, that would allow you to get the same information directly.You will also need to pay close attention to the spectra of whatever light source is used to illuminate the sample. Traditionally incandescent bulbs are nearly always used for this purpose because of their uniform spectra. It might be possible to use a white LED light source for your project, but the very uneven spectra is going to complicate things.
Spectrum analyzer affcted by external trigger signal - Page 1
Forum section: electronics / beginners

author: Guangtao Zhu
author_rank: Newbie
timestamp: October 29, 2024, 05:26:29 am
content: I use an electrical spectrum analyzer (ESA) to observe a 2.5-GHz signal. Then I observe the Y-output of the ESA in a oscilloscope (OSC) (Channel 1, CH1), as shown in Fig. 1. This is the desired spectrum.Then, I need to send a trigger signal (100 KHz) from a function generator (FG) to the OSC. However, if I connect the trigger signal to either CH2 or EXT TRIGGER port, the spectrum displayed in the ESA completely changes, as shown in Fig. 2. It looks like several narrow and unnatural fast-sweeping peaks. It is completely not the spectrum I need. How can the ESA be affected by a signal connected to the OSC?Same thing happens when I connect the trigger signal to the external trigger port of the ESA, as shown in Fig. 3.In all three cases, the ESA runs in the free runnning mode without being controlled by the trigger signal.What is the possible cause of this problem and how can I solve it? I want to observe the correct spectrum while using the trigger signal.
Spectrum Analyzer + EMC prob for motor magnetic fields  - Page 1
Forum section: electronics / beginners

author: SirRage
author_rank: Contributor
timestamp: August 03, 2021, 07:06:17 pm
content: I’m interested in experimenting with motor winding configurations. First I’ll try modeling them in software (once I figure out what package will work) and then build a test setup and then I want to be able to inspect the magnetic fields to see if they match the model, or if the model was just broken.I was looking at getting a TekBox EMC prob and probably a Spectrum Analyzer. I don’t have either of these but I imagine that’s what I need.As for the magnetic model software, I’m guessing MatLab + Simlink is probably where I want to start. Thanks!
Spectrum Analyzer Front End ESD Protection - Page 1
Forum section: electronics / beginners

author: sbvr4
author_rank: Contributor
timestamp: February 06, 2020, 03:35:01 pm
content: Hi,What is the most robust ESD protection method for the front end of a spectrum analyzer, or any ESD sensitive input, when not in use? I have two young children always running around. I don't have a lab set up, so my equipment is constantly moving around. I would like to protect my SA as much as possible against possible damage caused by ESD.Would a direct short offer the best protection since ground and the input are always at the same potential? Or a 50ohm termination kept on the input? Or the basic plastic dust cap?Thank you,Sbvr4

author: jlake
author_rank: Contributor
timestamp: February 06, 2020, 05:39:54 pm
content: I would recommend a few things:Keep ESD protective covers on RF connectors i.e. an ICP polymer with a low surface resistivity and something which meets the static decay requirements/regulations of whatever country you're inKeep the SA plugged in and ensure it's sufficiently grounded i.e. don't use an extension cable, etc.I don't know your circumstances, but surely it isn't*that*hard to keep it out of reach of your kids? Usually just putting it on a shelf or a high worksurface is sufficient to stop them meddling with something. If you're using it in a non-static-safe work environment, then preventing ESD damage will be difficult regardless of whether your kids are there or not. If that's the case, you should exercise good ESD practices like shorting the outer and inner conductors of coaxial cables before connecting them to your SA.From experience, a SA (along with most test and measurements equipment) is more likely to be damaged through mechanical means by inexperienced operators than ESD. Kids accidentally bumping, scratching or flexing the RF connectors poses a more likely threat to the welfare of the instrument.I hope that helps.

author: sbvr4
author_rank: Contributor
timestamp: February 07, 2020, 11:19:48 am
content: Thank you for your thoughtful response, jlake. I ordered some mil-spec antistatic caps. I had been holding off since I couldn't seem to find any that permitted purchasing less than a 1000. Plus I have several 50ohm terminations laying around. I liked the idea of terminations (50ohm or short) because they're threaded on. I ended up buying a small lot of caps on eBay.Thanks again,Sbvr4
Spectrum Analyzer RBW vs VBW - Page 1
Forum section: electronics / beginners

author: KD0RC
author_rank: Regular Contributor
timestamp: February 25, 2014, 03:38:36 am
content: I recently bought a Rigol DSA 815 spectrum analyzer. So far, I am getting along with it just fine. One thing I am just not clear on, however, is the difference between Resolution Band Width (RBW) and Video Band Width (VBW). I understand the concept of RBW - it is the 'window' that you are looking through at any given time during the course of the sweep. A smaller RBW means seeing more detail in the trace at a cost of more time to do so. This is not a problem for steady-state signals, but can be problematic for quickly changing signals. Please let me know if I am confused here...So what does VBW really mean? The SA by default keeps the RBW and VBW the same, but if I unlink and set them differently, it seems like VBW applies some kind of averaging, but maybe not over as many samples as video averaging. Just guessing now... Any help understanding this would be much appreciated!Thanks & 73,Len, KD0RC

author: rfbroadband
author_rank: Unknown
timestamp: February 25, 2014, 04:22:06 am
content: as you indicated correctly, the Res BW is set by a bandpass filter in the IF path. The video bandwidth sets the low pass filter bandwidth after the detector the therefore filters out out the noise...I created a simple example: 500 MHz CW into a spectrum analyzer for two different ResBW and VB settings, which should illustrate what I mean. Please note that VideoBW and ResBW are often coupled or set automatically by the analyzer, so if you want to adjust them independently (or manually) you need to disable the for example "Video BW auto" setting. Different manufacturers use different naming conventions...Hope that helps:

author: grego
author_rank: Frequent Contributor
timestamp: February 25, 2014, 04:31:08 am
content: As usual W2AEW has an awesome video describing both in detail:

author: w2aew
author_rank: Super Contributor
timestamp: February 25, 2014, 04:38:25 am
content: Quote from: grego on February 25, 2014, 04:31:08 amThanks for posting my video.In a nutshell, RBW is the pre-detection filtering, and VBW is the post detection filtering.

author: KD0RC
author_rank: Regular Contributor
timestamp: February 25, 2014, 05:13:02 am
content: Thank you all for this! Alan, that was a fantastic video and explained it perfectly. I was thinking of VBW as averaging, but now that I see that it is a LPF, it makes more sense. A narrow VBW in conjunction with video averaging lets really weak sigs stand right out. I put an antenna on the input, tuned it to 2.5 MHz, and can see WWV including the upper and lower sidebands for the 100 Hz tick, the 500 and 600 Hz tones and what looks like a 440 Hz tone. I think the 440 might be the pulse coding for sending the date and time.You guys are making the learning experience quite pleasurable!Thanks & 73,Len, KD0RC
spectrum analyzer showing dBuV - Page 1
Forum section: electronics / beginners

author: kumar
author_rank: Contributor
timestamp: December 22, 2014, 07:37:08 am
content: I have a spectrum analyzer which displays dBuV on y axis. Is it the field strength that is displayed? ( I mean, dBuV/m)

author: IconicPCB
author_rank: Super Contributor
timestamp: December 22, 2014, 08:22:41 am
content: NO....

author: PE1RKI
author_rank: Regular Contributor
timestamp: December 22, 2014, 08:41:29 am
content: with an antenna used for emi measurements and a correction table, then yes.

author: kumar
author_rank: Contributor
timestamp: December 22, 2014, 09:02:34 am
content: I forgot to mention, a near field probe is connected to the analyzer to check the emission from an equipment.

author: PE1RKI
author_rank: Regular Contributor
timestamp: December 22, 2014, 10:23:57 am
content: then you should be able to load a correction or normalisation table into the spectrum analyzer or some other way to calibrate it.

author: IconicPCB
author_rank: Super Contributor
timestamp: December 23, 2014, 03:05:11 am
content: You sure?
Speed controlled electric motors - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: August 22, 2018, 02:03:31 am
content: Hi All,Sorry for the silly question, google isn't really helping, how would I go about finding a motor for a project, what I do have are a very particular set of needs (get the movie reference?):48v, 1AIdeally it has internal electronics and I just feed it 48v, 5v and PWMSpeed from 500rpm to 10000rpmThe "can length" should be less than 50mmAre there standard sizings, are there suppliers of a variety of motors, in Australia would be ideal?Are there any physics issues with such a motor?Thanks.Richard

author: IconicPCB
author_rank: Super Contributor
timestamp: August 22, 2018, 10:48:06 am
content: google Anaheim automation
Speed controller issues - Page 1
Forum section: electronics / beginners

author: adiorio110
author_rank: Newbie
timestamp: January 11, 2025, 10:20:29 pm
content: Hi AllI sure one of you guys can figure this out.I have a motor I want go clockwise for 10 seconds stop for 3 seconds and go counterclockwise for 10 secs and repeat several times. I got that to work fine with forward reverse motor controller.Problem is the motor is 3000rpm I want to be able to lower and control speed.The speed control also works fine independent from the motor controller (Only test in one direction)12V 3000rpm motor cw/ccwhttps://www.amazon.com/gp/product/B07ZNX5MK3/ref=ewc_pr_img_5?smid=A142RLYNPQ7MGH&psc=15V - 24V Motor Controller Motor Forward/Reverse Controller Timing Delay Time Cycles Relay Motor Controller Board with LED (https://www.amazon.com/dp/B07S1B4H1Q?ref=ppx_yo2ov_dt_b_fed_asin_title)When I wire in the Speed controller with the motor controller it only works in forward directionit will spin forward 10s stop 3s next ten secs will pulse the motor but will not spin then it will again go forward for 10sI will enclose pictures of what I haveThank YouAnthony

author: BeBuLamar
author_rank: Super Contributor
timestamp: January 11, 2025, 11:54:31 pm
content: Do you have information on your motor controller?

author: adiorio110
author_rank: Newbie
timestamp: January 12, 2025, 12:50:30 am
content: Sorry it did not come with instructionsJust have youtube video on setting uphttps://youtu.be/Y1gwOkPtqCg?si=jhfkpFysh7cmBelZ

author: adiorio110
author_rank: Newbie
timestamp: January 12, 2025, 05:34:40 am
content: I just figured what may be a solution.. If I use a power supply that I can regulate voltage I can make it work as I need...Will this cause a problem ?
Speed of an object in a solenoid - Page 1
Forum section: electronics / beginners

author: montoyo
author_rank: Newbie
timestamp: May 25, 2015, 12:13:48 am
content: Hello everyone,First I do apologize for my terrible English and my noobness at electronics.I was looking for the formula to compute the speed of an object in a cylindrical solenoid.This is what I've found:B = µ0*N*I/LF = B*I*L= µ0*N*I²And according to newton's second law:a = F/m= µ0*N*I²/mFirst question: is this formula correct?This seems weird because it means that the acceleration of the object inside the solenoid doesn't depend onthe length of the solenoid (L vanishes).Second question: what is N?Okay; it's the number of cable loops around the solenoid; but around the whole solenoid?Or only around the part of the solenoid where the object stands?Thanks in advance for your help.

author: IanB
author_rank: Super Contributor
timestamp: May 25, 2015, 12:42:44 am
content: The short answer is "zero". The force on an object (such as a steel ball) inside a solenoid is zero.Regarding your equations, you have:B = µ0*N*I/L = µ0*I*(N/L)The important thing here is that the field intensity depends on the number of turns per unit length. For an "infinitely" long solenoid the field is the same everywhere. If the field is the same everywhere and the object inside it is symmetrical, then the object will experience no force as all magnetic forces will balance out to zero.Obviously if the solenoid has finite length, then the field will change near the ends of the solenoid and objects here will experience some force due to the field gradient.Therefore, the answer to your question is more complicated than you think it is, and a simple answer is not possible.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 25, 2015, 01:48:19 am
content: The Maxwell stresss = B^2 / (2*mu_0)is a pressure like any other, therefore, what causes things to move is a difference. In the middle of a solenoid, the force is zero, just as the force inside a gas cylinder is zero. An opening at the end, where there is a gradient or difference, is what pushes things around.Tim
speed sensing - Page 1
Forum section: electronics / beginners

author: Dexter12353
author_rank: Newbie
timestamp: May 18, 2015, 04:10:43 am
content: I am working on making a speed sensor work for a project I have been working...the sensor the speed gauge came with was extremely weak. It literally had to be less than 1mm away from the magnet to pick it up. Do you guys think I could purchase some stronger sensor and get it setup so it can detect a magnet from roughly 5mm away?I looked into hall effect sensors and got lost when it said required gauss, I don't know exactly how strong the magnets are, but a screw driver will stick to the ones already installed. I also have some rare earth magnets that I can stick on top to make them stronger.Any help is extremely appreciated!

author: Dago
author_rank: Frequent Contributor
timestamp: May 18, 2015, 04:36:58 am
content: The sensor is most likely a reed switch. To replace it with a Hall sensor you'd need a comparator in between. Just stick a stronger magnet and it will probably work well enough.

author: Psi
author_rank: Super Contributor
timestamp: May 18, 2015, 06:27:30 am
content: +1 for bigger magnetYou can get free rare earth magnets from around the lens in old CD/DVD drives and larger magnets from hard disk drives at the pivot point of the head arm.

author: mikerj
author_rank: Super Contributor
timestamp: May 18, 2015, 07:19:00 am
content: Quote from: Dago on May 18, 2015, 04:36:58 amThe other thing to note with reed switches is that they are very sensitive to orientation with respect to the magnetic field. They tend to be least sensitive when they are parallel and centred to the face of the magnet, applying the field to one end of the reed switch greatly boosts the range over which they can activate.

author: Dexter12353
author_rank: Newbie
timestamp: May 18, 2015, 02:42:30 pm
content: I'm sorry for not mentioning the sensor it came with was 3 writes...1 12 wire and a ground
Speed/hall sensor types - Page 1
Forum section: electronics / beginners

author: THRobinson
author_rank: Newbie
timestamp: April 03, 2020, 06:00:46 pm
content: Hey guys, I know very little about electronics, just the bare basics with semi-decent soldering skills.I am building a guitar pickup winder. To be cheap and easy I could buy this5 digit display with sensorhttps://www.ebay.com/itm/223331093919It's battery powered for the display but works and reads 1200rpms. The motor I will be using is a 12v 1200rpm, and I need 5-digits because pickups are around 18000 windings.I would however like a powered displayhttps://www.ebay.co.uk/itm/293493654999Looks like rpms are fine, 5-digits, etc... Where I got lost was the sensor. NPN, PNP, closed, open, 2wire, 3wire....plus the digital display has no reset, which I assume is simply a momentary switch attached?Hoping to get some advice... Again, no biggie to use the battery lcd, it's already done and ready to go, just rather the led display because easier to read. Looking to run off a 12v power supply... Has 2 motors, 1200rpm and 10rpm, both 12v. Will connect a motor controller to each for speed and reverse. Thanks.

author: THRobinson
author_rank: Newbie
timestamp: April 06, 2020, 04:50:56 pm
content: Anyone?

author: mikerj
author_rank: Super Contributor
timestamp: April 06, 2020, 06:41:20 pm
content: The input is active low, so you need a sensor that pulls it's output to ground when it detects whatever you wish it to detect. For a hall effect or inductive proximity sensor you want a NPN output (it does say this on the last picture). You may be able to use a simple reed switch, though 1200 RPM may be too fast for reliable operation so I wouldn't recommend this. Likewise the reset input is active low, so a push button switch wired to 0v and the reset input should do the job, assuming the counter has it's own pull-up resistor on board.Since the LED counter does not come with a sensor, so the final cost will be well above the LCD display counter that does come with it's own sensor.

author: thatguy1988
author_rank: Newbie
timestamp: April 09, 2020, 07:30:00 am
content: See the following page for information about Hall sensors including the difference between PNP and NPN type.https://thesensorshack.com/sensors/hall-effect-proximity-sensor/You will need to choose a high frequency Hall sensor. They sample at frequencies up to 30 kHz, which to be honest is not enough for very high frequency audible sounds, but I don't know what the highest frequency note on a guitar is. You could also consider an eddy current sensor which is like an inductive sensor but with an air core (instead of an iron one). It can sample at up to 100 kHz.I just saw that the sensor you posted counts at 20 Hz, that is very slow! Actually it says that it is an inductive sensor, these work at lower frequencies than Hall sensors because they consists of a coil wound around an iron core, excited by An AC signal and the iron core has a sort of electrical inertia which limits sampling rate. As a said in the previous paragraph, an eddy current sensor has an air coil and therefore has a sampling rate faster than even Hall sensors.
Speeding Edge "Right the first time" handbook - Page 1
Forum section: electronics / beginners

author: christerb
author_rank: Newbie
timestamp: November 01, 2019, 04:59:30 pm
content: I wanted to ask Speeding Edge (speedingedge.com) if they had any plans for a new edition or a reprint of the "Right the first time" handbook. However my e-mails to them bounced. I know the handbook can be downloaded for 25 USD per volume, but I much prefer to read a printed book. Also I am not sure I want to pay in advance if they cannot be contacted. Used copies are available for ridiculous prices. Does anyone know of their plans?

author: christerb
author_rank: Newbie
timestamp: November 02, 2019, 03:25:17 pm
content: It seems I have to answer myself ;-) Even though my e-mail bounced, I got an answer from speedingedge.com. There will be no more hard copys of "Right the first time". I did order volume one and received a download link by e-mail.
SPI bit banging; MCP3208; Raspberry;error - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: July 14, 2015, 04:09:57 pm
content: 1. I am using raspberry pi 2 board with raspbian loaded. need to do SPI by bit banging & interface MCP3208.2. I have taken code from here, it is written for MCp3008(10 bit adc):https://github.com/raspberrypi-aa/raspberrypi-aa/blob/master/spi_bitbang_test.py3. Only change i had made in code is instead of callingadcValue = recvBits(12, clkPin, misoPin)I had calledadcValue = recvBits(14, clkPin, misoPin)Since have to receive 14 bits of data.4. Problem is code is not working. It keeps on sending random data ranging from 0-10700. Even though data should be max 4095. It means I am not reading data correct.5. Problem which I think is since MCP3208 has max freq = 2Mhz , but in code there is no delay between two consecutive data read or write. I think I need to add some delay of 0.5us whenever I need to transition clock sicen I am operating at 1Mhz.6. For some delay I am currently reading these:https://projects.drogon.net/accurate-delays-on-the-raspberry-pi/
SPI bus packet structure - Page 1
Forum section: electronics / beginners

author: Randall W. Lott
author_rank: Regular Contributor
timestamp: August 31, 2012, 04:59:32 pm
content: Does anyone know of a resource for learning the SPI protocol? I would like to decode the MOSI and MISO lines by hand.I couldn't find any resources on how packets are structured or if there are common commands, such as the packet start and stop.Thank you.

author: JuKu
author_rank: Frequent Contributor
timestamp: August 31, 2012, 05:45:05 pm
content: SPI is much simpler than that, there is no universal commands, packet structure or such. SPI simply gets a few bits from here to there. What those bits mean is application specific. Seehttp://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus.
SPI Master/Slave setup with PIC MCU - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: February 01, 2024, 03:48:21 pm
content: I'm setting up two PIC 16LF18324 MCUs one as master and other as Slave to communicate through SPI, I want to know how does slave knows that its a start of data receive event,does it start reading right after SS' get low or it starts reading incoming bits on first change of clock event. ?if interrupts are enabled, does this event also triggers the interrupts?When does master start sending data, right after SSP1BUF register loaded with data? or after loading data we need to trigger something to tell uC that its time to start shifting data.I'm getting help from datasheet and was going to start writing code for it but i was not clear about ponts mentioned above, datasheet is attached.

author: DavidAlfa
author_rank: Super Contributor
timestamp: February 03, 2024, 08:25:24 am
content: Spi is always driven by CS/SS pin. You might have many slaves, each with it's own CS, sharing SCK/SDI/SDO.Why are you attaching an old preliminary datasheet? Everything is in the website, also updated:https://www.microchip.com/en-us/product/pic16f18324Read 30.2.5 SLAVE SELECT SYNCHRONIZATION

author: bidrohini1
author_rank: Contributor
timestamp: February 03, 2024, 01:12:38 pm
content: The actual transmission is triggered by either generating a clock signal or pulling the SS line low, depending on your configuration.

author: DavidAlfa
author_rank: Super Contributor
timestamp: February 03, 2024, 01:24:55 pm
content: Well, yeah, you can skip CS... but it's a bad idea and complicates things, the devices can get out of sync.SS-driven SPI automatically resets the SPI peripheral.
SPI modes, which is correct? - Page 1
Forum section: electronics / beginners

author: fabiodl
author_rank: Frequent Contributor
timestamp: July 11, 2023, 01:27:13 am
content: Inhttps://www.allaboutcircuits.com/technical-articles/spi-serial-peripheral-interface/Mode 3: Clock phase is configured such that data is sampled on the rising edge of the clock pulse and shifted out on the falling edge of the clock pulse.instead, inhttps://www.analog.com/en/analog-dialogue/articles/introduction-to-spi-interface.htmlSPI Mode 3, CPOL = 1, CPHA = 1: CLK idle state = high, data sampled on the falling edge and shifted on the rising edge.Which is correct?

author: ejeffrey
author_rank: Super Contributor
timestamp: July 11, 2023, 02:29:51 am
content: The former is correct.The CPHA definition is in terms of "leading" and "trailing" edges where the meaning of leading and following depend on the "idle" state from CPOL. It's a super confusing and annoying spec.

author: ArdWar
author_rank: Frequent Contributor
timestamp: July 11, 2023, 02:52:15 am
content: That AD article is incorrect. Their timing diagram, while technically correct and actually work, don't even help illustrating the difference.For SPICPHASEit's usually easier to remember the convention as leading/trailing edge instead of rising/falling edge

author: fabiodl
author_rank: Frequent Contributor
timestamp: July 11, 2023, 11:29:33 pm
content: Thank you. It was surprising that a page for beginners is correct and a silicon maker page is wrong.

author: pdenisowski
author_rank: Super Contributor
timestamp: July 12, 2023, 09:55:57 am
content: Quote from: fabiodl on July 11, 2023, 01:27:13 amI actually used this exact same example in my video on SPIhttps://youtu.be/0nVNwozXsIc?t=473(Back up a minute or two for the explanation of CPOL and CPHA before the example)

author: pdenisowski
author_rank: Super Contributor
timestamp: July 12, 2023, 10:00:58 am
content: Quote from: ArdWar on July 11, 2023, 02:52:15 amYes - I always refer to this as "leading / trailing" or even "first / second" edge to avoid confusion.
SPI op codes for atmel 25640 - Page 1
Forum section: electronics / beginners

author: kenn
author_rank: Contributor
timestamp: March 03, 2017, 03:52:41 pm
content: Hi there,I have an Atmel flash chip that I de-soldered and attached to a prototype board so I could learn about SPI. the datasheet is in the link below.http://www.atmel.com/Images/Atmel-8535-SEEPROM-AT25320B-640B-Datasheet.pdfI have a bus pirate and can get into the SPI menu but I am not understanding how to send the op-codes? I want to simply read data but everything I have tried doesn't seem to work. for example in table 6-1 of the data sheet I can see that READ is 0000 X011 so I have tried typing that in, I have tried that plus an address range and various other permutations. Does anyone have an example of what to actually enter into the prompt to get some data back? On YouTube there is a great videoabout SPI using the PI but in the video he mumbles something about "not knowing the right codes" so it isn't returning anything, I was hoping to see an example in there but it doesn't tell me anything. Hopefully someone can point me in the right direction.Thanks

author: elecman14
author_rank: Unknown
timestamp: March 03, 2017, 06:15:50 pm
content: Take a look at this:https://hackaday.com/2009/06/30/parts-spi-eeprom-25aa25lc/Also this is a good reference:http://dangerousprototypes.com/docs/Bus_Pirate#Chip_demonstrations