hybridfree/eevblog-posts huggingface dataset:
NodeMCU ESP8266 delay slowing down - Page 1
Forum section: electronics / beginners

author: dusterthefirst
author_rank: Newbie
timestamp: April 21, 2020, 07:02:06 pm
content: I have recently purchased a NodeMCU (1.0) ESP8266 and connected it up to a speaker that I salvaged from an old alarm clock, pictured below. I connected the red wire to pin0 and the black wire to ground, as I assumed it would work. and started playing around with tones using the Arduino library (tone()) with delay()s between them to play a song. At first it worked very well, and kept almost perfect time. But listening to it today, it is playing the tones noticeably slower than it used to. I thought I might have drawn too much current from the board and blew a component, causing the clock to somehow slow. But i have no idea how to check or fix the problem. Any other ideas would be welcome. (I have tried to cut the times in half and it gets back to playing about the right tempo, but I am still perplexed as to what caused the issue.

author: Manul
author_rank: Super Contributor
timestamp: April 21, 2020, 07:53:00 pm
content: Well, you should never connect a speaker directly to MCU. Not only it is too big load, but it is also inductive. Back EMF of an inductive load can do unpredictable things for such a delicate chip. Maybe clock dividers failed, thats hard to say.

author: ozcar
author_rank: Frequent Contributor
timestamp: April 22, 2020, 06:00:48 am
content: As Manul said, not a good idea to connect the speaker directly, but did you perhaps change the "crystal frequency" setting in the IDE?

author: dusterthefirst
author_rank: Newbie
timestamp: April 22, 2020, 01:16:32 pm
content: I thought about that, but the changing it from 80MHz to 140MHz just causes the output pins to go haywire and does not speed it up at all

author: ozcar
author_rank: Frequent Contributor
timestamp: April 22, 2020, 06:32:43 pm
content: Quote from: dusterthefirst on April 22, 2020, 01:16:32 pmI was wondering if you had changed the "Crystal Frequency" rather than the "CPU Frequency" that you are talking about (80MHz vs 160MHz actually). However, I just checked, and I notice that you only get the option to change the crystal frequency (26MHz vs 40MHz) if you select a generic board, like say "Generic EP8266 Module" rather than a specific known board like "NodeMCU 1.0". So, scrap that theory, assuming you have not selected a generic board.
NodeMCU Network Temp Probe - Page 1
Forum section: electronics / beginners

author: paulca
author_rank: Super Contributor
timestamp: January 13, 2018, 08:19:19 pm
content: Well that was easy.Dallas DS18B20.Soldered a 4k7 across Data and VccFemale to female jumper leadsVCC to 3.3VData to D2GND to... well GNDHeat shrink the Dallas sensorUSB wall wart.Sprinkle some code.Voilà Wifi enabled temp probe.Stuff it in a corner of a remote room.Now I have this little set:QuoteBR is bedroom - the NodeMCUDS is downstairsOD outdoors (hanging out the window on an RJ45)AP air pressure, HM humidity, AT aux_temp (provided by the pressure/humidity sensor)All of the above from the living room PI3Still sucks that the power supply costs more than the flipping NodeMCU. Especially as I could only find a 2A Raspberry PI wall wart and they aren't cheap.Code:Code:#include <OneWire.h>#include <ESP8266WiFi.h>#include <DallasTemperature.h>#include <WiFiUdp.h>// Put your wifi SID and password in a file of this name// or uncomment and edit these// const char* ssid = "mysid";// const char* password = "mypassword";#include "credentials.h"#define ONE_WIRE_BUS D1OneWire oneWire(ONE_WIRE_BUS);DallasTemperature sensors(&oneWire);void setup() {WiFi.begin(ssid, password);sensors.begin();}void loop() {sensors.requestTemperatures();double temp = sensors.getTempCByIndex(0);WiFiUDP Udp;Udp.beginPacket("10.0.0.3", 9999); // host, portchar data;memset(data, 0, 255);int len = snprintf(data, 255, "BR:%.2f:'C", temp); // KEY:VALUE:UNITUdp.write(data, len);Udp.endPacket();delay(5000);}EDIT:References/credits:http://arduino-esp8266.readthedocs.io/en/latest/esp8266wifi/udp-examples.htmlhttps://github.com/esp8266/Arduino/issues/584WTF?http://www.hobbytronics.co.uk/ds18b20-arduino

author: paulca
author_rank: Super Contributor
timestamp: January 13, 2018, 08:24:49 pm
content: If you want to use it without a "hub" to receive the UDP you would be better off following the example in the link which uses the ESP8266 Webserver instead.
noise added to AC coupled inverting amplifier vs dc coupled - Page 1
Forum section: electronics / beginners

author: SArepairman
author_rank: Frequent Contributor
timestamp: April 12, 2014, 03:04:12 am
content: How do I determine the amount of noise added to a AC coupled inverting amplifier by the coupling capacitor drain resistor?Typically a 100k-1M ohm resistor is used to make sure the capacitor never fills up. But I thought a 100k resistor had quite a high noise, compared to a low noise op-amp.If an amplifier has X nV/sqrtHz noise how would I determine the new nV/sqrtHz noise once a 100Kohm resistor is grounding the op-amp input? *assuming G=1 buffer*This tool might help:http://www.daycounter.com/Calculators/Thermal-Noise-Calculator.phtmlbut I don't know what to do.*this is done as a easy method of dealing with offset voltage problems.based on something I saw on a TI website:http://www.analog.com/static/imported-files/tutorials/MT-047.pdfpage 4seems to imply that a 300k ohm resistor to ground infront of an op amp would contribute to 70nV/hz noise.this basically takes AC coupling out of the question for a low noise system.. right?

author: acbern
author_rank: Frequent Contributor
timestamp: April 12, 2014, 12:19:36 pm
content: now I see what you are looking for in your other post.what you should do is to claculate the noise generated by the input resistor. use the temperature, frequency range (e.g. 20khz for audio) and resistor and insert in the tool.do the noise calculation with the amplifier (no need to use the formula, just calculate via the nv/sqrt hz data given).your combined noise then is: un total = sqrt (un resistor^2 + un amp^2)
Noise at full bandwidth - Page 1
Forum section: electronics / beginners

author: elki
author_rank: Regular Contributor
timestamp: August 02, 2024, 12:39:40 pm
content: .

author: Vovk_Z
author_rank: Super Contributor
timestamp: August 02, 2024, 06:48:20 pm
content: .

author: RoGeorge
author_rank: Super Contributor
timestamp: August 02, 2024, 07:19:28 pm
content: . ._ _ .... ._ _

author: radiolistener
author_rank: Super Contributor
timestamp: August 03, 2024, 03:58:50 am
content: ..–.– ..–.– ..–.–

author: Vovk_Z
author_rank: Super Contributor
timestamp: August 03, 2024, 05:01:49 pm
content: --..--
Noise Filter? - Page 1
Forum section: electronics / beginners

author: Undweeber
author_rank: Regular Contributor
timestamp: April 04, 2018, 02:16:39 pm
content: Why does a microwave need a noise filter, I though that would be needed by delicate electronics like a blue ray player, microwaves seem crude enough to get by without it 🤔

author: Cliff Matthews
author_rank: Unknown
timestamp: April 04, 2018, 02:46:30 pm
content: It's not so much what gets in, as what gets out. Everything must play together. EMI leakage back out to the line will make or break certification approval. * see image

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 04, 2018, 02:57:41 pm
content: Which kind, transformer or inverter?The latter, simply because any SMPS needs it.The former, I've only ever seen a pair of ferrite rod chokes on the cathode connection, and that's it. The emissions at 2.45GHz are apparently not very well controlled, and anything getting out along the line cord, or leaking out the enclosure, is probably invisible compared to the mess leaking out around the door.Tim

author: Undweeber
author_rank: Regular Contributor
timestamp: April 04, 2018, 04:22:54 pm
content: @bothMicrowave I took apart is General Electrics, but every single component inside is Samsung, the filter isSN-UF11B

author: Cliff Matthews
author_rank: Unknown
timestamp: April 04, 2018, 04:35:48 pm
content: So is it broken, or was this a tear-down?

author: Undweeber
author_rank: Regular Contributor
timestamp: April 04, 2018, 10:26:00 pm
content: it's a working microwave that was on the sidewalk, a store was moving to a different location and didn't want their dirty microwave i guess, it's a dream come true for me lol, now i have a 21VAC motor which i can convert into a hand crank generator for my infinite power flashlight project, and have a powerful magnetron, and tons of other goodies, very high quality build inside

author: Cliff Matthews
author_rank: Unknown
timestamp: April 05, 2018, 12:33:34 am
content: Was it transformer or inverter?For transformers, tape over primary to protect and use a hacksaw carefully on one side of secondary, then toss it in vise to tap out the secondary till it falls out the other side.. (good copper scrap). Makes a quick spot welder with 4 turns of a short chunk of welding cable and some RL26 solder-on lugs.

author: Undweeber
author_rank: Regular Contributor
timestamp: April 05, 2018, 03:18:53 am
content: it has a huge transformer inside, i will definitely save it for a future project, but at this mooment i dont need a welder, i used to hate electronics, but holy shit monkey balls theres so much you can do with it, i keep getting pulled in more and more
Noise in CRO - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: January 29, 2015, 11:57:54 am
content: I am using CRO to measure area under grap plotted by DAC output from MCU.Problem is when I put probe on MCU output pin, there is random noise in signal i.e signal is not smooth.That why I cannot read exact area under curve from MCU.Earlier I thought noise could be from MCU pin. But I put the probe on GND pin of MCU, same random noise appears on it also.CRO ground pin is connected to ground pin of MCU.

author: Andy Watson
author_rank: Super Contributor
timestamp: January 29, 2015, 04:05:49 pm
content: The noise is probably being picked-up in the ground lead of your probe. Basically, wires have inductance, even short wires have significant inductance at higher frequencies! The video linked in this thread explains the problem:https://www.eevblog.com/forum/index.php?topic=12540.0

author: katzohki
author_rank: Frequent Contributor
timestamp: January 29, 2015, 05:16:49 pm
content: What is your ground of the CRO connected to?

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: January 30, 2015, 05:05:18 am
content: @andy,thanks it helped
Noise in single vs dual supply - Page 1
Forum section: electronics / beginners

author: ricko_uk
author_rank: Super Contributor
timestamp: January 02, 2020, 03:40:31 am
content: Hi,using an instrumentation amplifier (or any amplifiers) and assuming in the specific application it can be connected to single or dual supply, which is better to keep supply noise to a minimum? Single supply or dual supply?Does dual supply introduce more noise?Whichever it is, could you please explain also why?Thanks

author: unitedatoms
author_rank: Frequent Contributor
timestamp: January 02, 2020, 04:31:58 am
content: I tried to calculate noise for two variants of supply. It looks like dual supply with uncorrelated voltage noise has small advantage. Consider single supply 10v with 10mv noise VS dual 5v/5v and 5mv noise each. The square root of sum of squares will be 7.07mv which is less than 10mv.Problem is that ripple of supplies is usually correlated. But references can have broadband noise in frequencies higher than ripples. So may be it is still a valid advantage.

author: ricko_uk
author_rank: Super Contributor
timestamp: January 02, 2020, 04:55:15 am
content: Thank you Unitedatoms,two questions:1) in my application it is slightly different from what you suggested. The option I have is 0 to 5V or -5V to +5V. What would it be in that case?2) in your example you assume that in the split supply you have half the noise. Why do you assume that? Would it not be the same noise for each rail (whether 0-10 or +/-5V?Thank you

author: gbaddeley
author_rank: Regular Contributor
timestamp: January 02, 2020, 05:05:32 am
content: With dual supplies, referenced to 0V, the noise in +5 and -5 will be uncorrelated, meaning the noise sum is less than their peak-to-peak sum. Read up on noise theory. Generally noise is not a design consideration for single vs dual supplies as the inst amp’s PS rejection will contribute lower noise than from other sources.

author: unitedatoms
author_rank: Frequent Contributor
timestamp: January 02, 2020, 05:17:20 am
content: With single 5 VS dual 5+5, the noise is X VS X*1.4142. So choose single supply.I assumed that single VS dual is for identical voltage span. If you double the span, then noise is proportionally grows as square root of sum of squares.I also assumed that noise amount is proportional to supply voltage, to give a fair comparison. No other reasons, just to make example simpler.

author: David Hess
author_rank: Super Contributor
timestamp: January 02, 2020, 01:50:45 pm
content: Blueskull posted what I was going to post. Correlated noise in the bipolar supply can be rejected more effectively by the power supply rejection instead of the common mode rejection. Tracking supplies have advantages in low noise circuits which can take advantage of this.Note that the power supply rejection curves shown in datasheets may actually be common mode rejection or open loop gain if the wrong test circuit was used.
Noise in system when laptop is connected to external supply - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 23, 2016, 04:59:03 am
content: I have a system in which pin is toggled. Pin toggle is viewed on CRO with 10x setting & peak detect. There are two cases:Case1: MCU board is powered by laptop usb power. CRO earth is connected to MCU board ground. laptop is powered from internal battery & no external supply is connected to laptop. SO CRO earth is connected to MCU ground which in turn connected to laptop ground via usb connector shield.In attaced pdf, page 1 shows the pin toggle waveform. It is nice & clean, no noise or whatever.Case1: Now external supply is connected to laptop also.Now suddenly there is noise in system. Page 2, shows the noise in pin toggle. Pin toggle time is still the same. (However pic shows it larger, I think its due to camera speed). But noise is present in system as shown.Then I connected CRO probe to ground of MCU where CRO earth probe is connected. Page 3 shows the noise in MCU ground also.1. What is this noise? One reason could be that now laptop is connected to earth, which is now connected to MCU ground. But this happened in first case also where CRO earth is connected to CMU ground?2. Is this actually a noise? Because noise is present both in pwer & ground of MCU, so I think if it is measured by differential probe then there will ne no noise in case2.3. is this noise dangerous for circuit, i.e it affects analog circuitry. If yes, how to get rid of this noise.PS: I have long wire coming thorugh CRO i.e separte earth probe & separte CRO probe. Another erason could be this is due to large CRO probe wire length. But if that would be case, it should happen in case 1 also.

author: haveissues
author_rank: Contributor
timestamp: February 23, 2016, 10:55:10 am
content: I had this exact thing happen to me along with an erratic touchpad. The laptop was given to me because of the touchpad and it turned out to be the cheap POS replacement power supply they bought was incredibly noisy. Hook your scope up to the laptop power supply output and you might find your problem.
Noise Margins Inverter - Page 1
Forum section: electronics / beginners

author: Benta
author_rank: Super Contributor
timestamp: November 17, 2023, 10:14:35 pm
content: Do your own homework.

author: etnel
author_rank: Contributor
timestamp: November 17, 2023, 10:24:16 pm
content: Thank you, just solved it. Nerd.

author: Benta
author_rank: Super Contributor
timestamp: November 17, 2023, 10:32:52 pm
content: Good.Insulting people is not the best entry to a forum you might need in the future.

author: etnel
author_rank: Contributor
timestamp: November 17, 2023, 10:35:58 pm
content: Was not intended as an insult. Sorry to hear that you felt that way!

author: Bud
author_rank: Super Contributor
timestamp: November 17, 2023, 11:05:19 pm
content: Very informative post, thanks guys.
Noise on scope due to laptop. - Page 1
Forum section: electronics / beginners

author: Mattjd
author_rank: Regular Contributor
timestamp: November 08, 2018, 01:09:39 am
content: So today in the lab I was at a work station, had a scope, generator, power supply on and in use, they were all plugged into the same surge protector. Additionally, my laptop was plugged into that same surge protector. My laptop (a macbook pro) was using the power supply that didnt have a ground plug (there are two types), there was a lot of noise on the scope, and when I unplugged the laptop it went away. Why?

author: Sylvi
author_rank: Regular Contributor
timestamp: November 08, 2018, 03:46:10 am
content: HiLaptops like cell phones have practically no shielding, which is why you should not have either one near your body. In both cases, all the emitted noise is microwave energy which is bad for you. There are a range of frequencies that intermodulate each other making a broad spectrum of noise that extends downward to frequencies your scope can easily see and that other equipment can pick up.You might also want to check if the wireless is turned on in the lap top. We bought a printer that was connected via USB but every time it was sent a print job it was trying to find a wireless connection. We had to go into the printer's menu to turn the wireless off. We have nothing wireless - no cell phones, no cordless phones, no cloud-printers, no wireless LAN. Everything is wired. Pretty much all wireless stuff and every CPU clock is in the microwave range. Desk top computers generally have better shielding. Your DSO has a computer, too, but it is a piece of industrial equipment with a designed longer life than the lap top, so it has proper shielding.
Noise - Page 1
Forum section: electronics / beginners

author: vargoal
author_rank: Regular Contributor
timestamp: February 15, 2015, 12:49:47 am
content: Hi EEVBlog Community,I am working on developing a modified SPI interface for robotics. Anyway I got the basic protocol working but I am trying to determine if a data validation should be added like a basic parity bit. Given the hardware I am using the clock speed of the interface is around 70 hz. I plan to test the system near a dc motor and under lower voltage conditons ot my arduino pro mini. Anyway I was wondering if there is anything else I should try that would cause line noise on the data lines which could result in data corruption. Any advice is appreciated.

author: Neganur
author_rank: Unknown
timestamp: February 15, 2015, 11:55:19 am
content: Hmm apart from your power source, you could try to use a function generator with a sharp square wave and see if you manage to couple some of that onto your data lines.With a 70 Hz SPI clock and 3V? 5V? You could also try and find some cheap power drill, those can be a good source of noise.But without knowing more about the environment or the power design I'd guess that anything with current surges will do.

author: mij59
author_rank: Frequent Contributor
timestamp: February 15, 2015, 12:04:34 pm
content: On and off switching of mains power to an inductive load works great, e.g. soldering iron with safety transformer.

author: vargoal
author_rank: Regular Contributor
timestamp: February 16, 2015, 10:57:58 pm
content: Thanks for your advice. I think I will start with the coupled square wave and then move on from there. To give you a little more detail I am using 3.3v logic and I am trying to get an arduino pro mini to talk to a HiTechnic Super Pro Board(see link below). To my knowledge only one other robotics team has done this and when I looked at their code it seemed overly complicated. I will try to post more details about the project including the code and pictures after I finish a little more of it.Hitechnic super pro boardhttp://www.hitechnic.com/cgi-bin/commerce.cgi?preadd=action&key=SPR2010
Noisy atMega1280 Input pin - Page 1
Forum section: electronics / beginners

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 06, 2011, 04:20:54 pm
content: i programmed arduino mega to become logic analyzerherebut one problem. when i connect directly the DDS digital output to atmega pins configured as input, the DDS analog signal shown in DSO become so noisy, the DDS signal is not high freq stuff, only around few KHz to few Hz, the noise is high frequency stuff 0.5-1Vpp. i thought when a mcu pin configured as input, it will become high impedance and very low loading to the source generator? so i dont get where this noise is coming from. i thought it will be blocked in and out of the mcu since hi-Z connection. how i connect the arduino and DDS is shown below. should i add extra filter or components before feeding in the arduino chip? if yes please advice personally or provide links. thanks.

author: Psi
author_rank: Super Contributor
timestamp: November 07, 2011, 03:55:00 am
content: Few ideas...0.5-1V p2p is pretty large so its probably something simple, like a grounding issue.Do you get noise when the signal connection is made or does the noise appear even before then when the cables ground connection is made?Move your DSO probe ground clip to the arduino ground. (if its not there already). If your measuring the signal with reference to a ground point that is far away from the arduino (like mains earth) you will probably see lots of ground noise.Try powering the circuit from something that's isolated. eg, if it's getting power from usb try an laptop running on battery.Check you have the pin pullup disabled. When a pin is set as input it will only be highZ if the pullup is disabled (pretty sure its off by default but i'm not too sure about the arduino environment).Double check you don't have some other code that's accidentally switching the port to output sometimes. As that would look like high frequency noise if it's happening in your main program loop. You could check this by putting the scope on the input pin without anything connected except a 10k resistor to arduino ground and another 10k to vcc. That will show if the pin is being accidentally switched to output or pullup enabled, (it should be half rail all the time).Some pins have other functions, check your not trying to use one of these other functions as it might be changing the pin to output.Also if you can post a better pic of your signal with and without this noise we might be able to tell what kind of noise it is and where its from.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 07, 2011, 12:25:06 pm
content: ok i spotted the problems. 1st and major, is when i'm tired, lack of sleep and motivation and ready to bed while posting this thread. 2nd, the green stuff at far left in the picture (connected to FG output) and my DIY 1/10X probe (with DIY yellow ring and white clip), should not be there. long ground loop also slightly contributed to the noise. the mentioned noise is shown below.
Noisy oscilloscope measurements - Page 1
Forum section: electronics / beginners

author: wsowa
author_rank: Newbie
timestamp: November 07, 2018, 12:21:46 am
content: So I've build an non-isolated SMPS, an AC->DC buck converter essentially. I run into some problems I described here:https://www.eevblog.com/forum/projects/acdc-buck-converter-noise-on-input-causes-heavy-ringing-on-output/msg1692356/#msg1692356.I have recently started some more experiments following suggestion in above thread that the noise might be picked up by probes/scope and I got to the point where I think I don't know how to use oscilloscope properly. Thus a thread in "Beginners" section.I thought I'll measure my SMPS using poor's man diff probe, i.e. use just two channels per measurement since the suggestion about ground and EM coupling problems. I have probes with the crocodile GND wire detached and no probe ground connected with "spring".So I have mains conected into the SMPS' input on a PCB and also to the mains L and N at the PCB terminal are connected to 2m long pair of wires open at the end with the switch on the hot wire. See the diagram below for a schematics and the scope measurement taken when I engage the switch: See scope1.png attachment. Clearly the output of the SMPS is noisy.Then I though "I'll measure just the mains and check what happens when I click the switch". But I left two other channels (for no reason really) connected to the PCB which in turn was not connected to anything. It was physically 50cm away with no power connected to it, just with probes on the output. Here's what I got: See scope2.png attachmentStill noise at SMPS output!That brings be to the conclusion that whatever I've seen on the scope and posted in the thread I linked at the beginning was likely a measurement noise. So the big question iswhat am I doing wrong?! Why do I see probes on remote unpowered PCB picking up a noise from switch of unloaded mains line? How to avoid it?

author: wstrzalka
author_rank: Newbie
timestamp: November 16, 2018, 08:48:55 am
content: Have you tried putting the circuit in the metal can (Faraday cage)?This will tell you whether it's the circuit ot the scope picking the noise ...

author: CatalinaWOW
author_rank: Super Contributor
timestamp: November 16, 2018, 05:33:08 pm
content: There are two general ways this noise can get into the scope, ground problems and air paths (call it EMI). For things like your setup an air path seems most likely. I suspect you have the unused channels in high impedance mode. If your scope supports it try putting them into 50 ohm mode, or just put 50 ohms across the inputs.All measurements require wires which act as antennas, and load the circuits being tested. Drawing a circuit with a simplified model of the scopes input (usually just a resistor and capacitor, but maybe an inductor also) can help you understand these effects, and help you make the compromises that are always required when hooking observation lines to a circuit.
Noisy power supply adapter - Page 1
Forum section: electronics / beginners

author: bborisov567
author_rank: Regular Contributor
timestamp: October 18, 2022, 05:20:06 pm
content: Recently i built a clock with arduino and max7221 for 7 segment display. I use old Nokia charger adapter as a power supply. It is connected to the Vin of the arduino and the max7221 is connected to the 5v rail. Everything is fine until i set the display at low brightness, then the adapter starts hissing. I have 220uf cap on the Vin rail and 10uf+100nf on 5v rail. My question is - can i do something or i should get good old transformer?

author: fourtytwo42
author_rank: Super Contributor
timestamp: October 18, 2022, 05:50:17 pm
content: Could well be it likes a minimum load, I assume as the brightness is reduced so is the load current. So maybe add a suitable resistor from 5v to 0v.If you happen to be on a long ADSL line these "Asian" power supplies can also wreck your broadband connection!

author: bborisov567
author_rank: Regular Contributor
timestamp: October 18, 2022, 07:09:43 pm
content: Yes, that seems to be the case! After adding 180 ohm resistor the hissing becomes barely audibly. Thank you!
Nokia 6610 / 6100 color lcd - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: January 17, 2017, 04:07:19 pm
content: Anyone knows where to get these?https://www.sparkfun.com/products/retired/569At one time these were easily available and a good deal for diyers who wanted to integrate them in their projects.There are few shops on ebay that sell them in small quantities but they are getting rarer by the day even Sparkfun has stopped selling them.Anyone knows any good reliable source or are there any alternatives?

author: mikerj
author_rank: Super Contributor
timestamp: January 17, 2017, 04:41:46 pm
content: AliexpressorBanggood.

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: January 17, 2017, 04:49:12 pm
content: Quote from: mikerj on January 17, 2017, 04:41:46 pmOK! thanks for the input.I see that these are using the ST7735, that's fair enough, I was under the impression that the nokia one's used the Epson S1D15G10 or Philips PCF8833 Controller.I would like to hear from folks that have used this one or any of the Nokia one's just to get their first hand experience about it.

author: amyk
author_rank: Super Contributor
timestamp: January 18, 2017, 03:23:08 am
content: ST7735 is a very similar command set to the PCF8833, although it uses 2-byte pixel addresses.http://wiki.s1mp3.org/LCMControllers

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: January 18, 2017, 04:23:04 am
content: Quote from: amyk on January 18, 2017, 03:23:08 amThat's some really good info.So currently is the ST7735 the only available choice? are there any other LCD's with controllers as popular as the ST7735?

author: lordvader88
author_rank: Frequent Contributor
timestamp: January 18, 2017, 04:42:31 am
content: wow I found a broken nokia 610 (yes 610) ages ago that had smashed outer glass. So today I took it apart and the LCD screen inside is perfect, not a scratch. Once I hook up 3.7V I hope it will work and be able to play games on it pr something. Otherwise what a waste of a nice screen and stuff
Nokia LCD problem - Page 1
Forum section: electronics / beginners

author: Lesterwyatt
author_rank: Regular Contributor
timestamp: January 01, 2015, 09:07:07 pm
content: Hello.I have interfaced a pic18f and RTC to a nokia to a 5110 graphical lcd.However i am having a few problems, i am using a lookup table to display the time using RETLW. (see below)My problem is when the table is called from the BCD value, its only calling and displaying 1 byte rather than 6 byts i.e.BCD value (00000001) 1.calls table and dissplays 0X00rather than 0x00 0x00 0x42 0x7f 0x40 0x00anybody know what im missing?Part of my code I am using for the Nokia 5110 lcd.6 byte value to display the number '1' on nokia lcdaddwf PCL,fretlw 0x00 //6 byte character mapretlw 0x00retlw 0x42retlw 0x7Fretlw 0x40retlw 0x00Thanks Lester

author: macboy
author_rank: Super Contributor
timestamp: January 02, 2015, 01:17:43 am
content: A lookup table like you implemented will return a single value based on the passed in value of W. For your table, if you call the lookup table with W set to 2, it will return 0x42 (in W). If W is set to 3, then it will return 0x7F. You won't get 6 values unless you call the table 6 times.Does that help?

author: Lesterwyatt
author_rank: Regular Contributor
timestamp: January 02, 2015, 02:03:48 am
content: Yes I understand, hmm wonder if I could put a value of 6 in a tmp register and have a decfsz and on every pass add 1 to bcd value? this way it would decrement down the retlw table based on the first received byte?i.e. received byte is 00000001. and adding 1 would be 00000010....lester
Nomenclature for power connector - Page 1
Forum section: electronics / beginners

author: Virosa
author_rank: Newbie
timestamp: November 27, 2016, 03:54:53 am
content: Hello all,I'm not a beginner to electronics, but I am a beginner to electronics that take power from the wall! I am repairing an old radio with a busted power supply, and it takes a "universal" 2-pin cord to get 120V from the wall here in USA.As I was drawing a DaveCAD-style schematic of what the power supply was all about, I noticed that the power connector has 5 pins! Very weird, I only expected 2 to get fed into the transformer. So I decided to look up power connectors on Mouser to see what those 3 are about, and I can't find any similar parts! I looked under "power to board", and filtered on "120V", and nada! Zip! Zilch! What gives?So here are my questions.(Pictures of connector attached):1) Is there an official name for the universal 2-pin connector? (example of mating cable:https://www.amazon.com/gp/product/B01HPWIDVS/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) Is IEC-320-C7 what I'm looking for?2) What are those 3 extra pins for? There are traces going to them, so they aren't just mechanical bosses, surely?3) Why didn't my Mouser search reveal any similar parts? Are these type of connectors no longer used?Thanks for any help you can offer!-Louie

author: G7PSK
author_rank: Super Contributor
timestamp: November 27, 2016, 03:00:33 pm
content: The other 3 connections are probably DC switching for battery operation, when the mains plug is inserted it disconnects the battery power and switches to the mains generated low voltage DC.

author: Virosa
author_rank: Newbie
timestamp: November 28, 2016, 01:47:49 am
content: That makes a lot of sense.I'm still curious why am I not seeing any comparable parts in digikey/mouser? Is IEC-C7 no longer used? Or is my google-fu incredibly weak lately? Because I'm not turning up any connectors that would work inside a small, inexpensive project.

author: sleemanj
author_rank: Super Contributor
timestamp: November 28, 2016, 01:58:23 am
content: C7 is the common figure-8 (aka shotgun) plug, and C8 is the matching socket, you r picture doesn't look like a figure 8 socket to me.It looks more like an IEC C10 Socket, which makes with a C9 plug - although your pins look round and according to the image below 9/10 are rectangular pins, so it may not be a standard IEC socket at all.
Non-antistatic soldering stations with earthed tip - Page 1
Forum section: electronics / beginners

author: AndrejaKo
author_rank: Frequent Contributor
timestamp: March 16, 2013, 12:55:56 am
content: I'm using Ersa RDS 80 soldering station which has high impedance tip connection to ground. From what I've read in their catalogs, it's not antistatic. On the other hand most descriptions of antistatic soldering irons say that the tip is grounded.So what else is needed to except grounded tip to have antistatic soldering iron and why would non antistatic soldering iron have grounded tip?
Non-conductive and non-corrosive gels for a lighting project - Page 1
Forum section: electronics / beginners

author: nathanpc
author_rank: Unknown
timestamp: November 02, 2015, 04:26:13 pm
content: I'm planning to do a little lighting project with some tiny glass bottles and really bright RGB LEDs. To give it a little better effect I was thinking about filling the glass bottles with some sort of gel, but since the LED pins are probably going to be in contact with the gel itself, I want to know if there are any non-conductive and non-corrosive gels that I could use for this project.

author: tooki
author_rank: Super Contributor
timestamp: November 02, 2015, 04:40:27 pm
content: I don't know about gels, but shattered tempered glass (which breaks into little pieces with relatively blunt edges) in a jar with a light inside makes a great effect.

author: DmitryL
author_rank: Regular Contributor
timestamp: November 02, 2015, 05:05:51 pm
content: Quote from: nathanpc on November 02, 2015, 04:26:13 pmHmm.. there is such thing as UV-curing gel. Used for gluing nails

author: SeanB
author_rank: Super Contributor
timestamp: November 02, 2015, 05:15:15 pm
content: Clear silicone gel grease, available as a sachet. Sold as a personal lubricant.

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: November 02, 2015, 05:41:33 pm
content: Quote from: SeanB on November 02, 2015, 05:15:15 pmDepending on the gel that stuff tends to turn yellow over time...Actualy this is an interesting question, I had something simmilar in mind and thought about that problem, too.I ended up thinking about silicon isolation oil as the "perfect" material, but that stuff is expensive as hell...

author: bugs
author_rank: Contributor
timestamp: November 02, 2015, 06:17:37 pm
content: Maybe vaseline / petroleum jelly?

author: dentaku
author_rank: Frequent Contributor
timestamp: November 02, 2015, 06:42:58 pm
content: This sounds like something Big Clive might know about.https://www.youtube.com/user/bigclivedotcomI hope he reads this.

author: continuo
author_rank: Frequent Contributor
timestamp: November 02, 2015, 07:27:33 pm
content: What's the purpose of the gel? If you want uniform illumination or light scattering I would fill the bottles with tiny glass perls or something similar...
Non ESD-Safe Soldering iron to ESD-Safe  - Page 1
Forum section: electronics / beginners

author: tronxkid
author_rank: Newbie
timestamp: June 17, 2011, 08:09:02 pm
content: I have finished reading a DIY tutorial about making a non esd-safe soldering iron to an ESD-safe soldering iron by just grounding the soldering tip.My question is DOES IT really make an ESD-Safe Iron? and Please share your thoughts about this method or any other method for Non ESD-Safe -> ESD-SafeTronxkid

author: johnmx
author_rank: Frequent Contributor
timestamp: June 17, 2011, 09:23:29 pm
content: That’s the only method I know of.Remember, it’s also important that you use an ESD Wrist Strap when handling/soldering ESD sensitive devices.
Non-flammable rechargeable batteries for electric bicycles - LiNiMnCoO2? - Page 1
Forum section: electronics / beginners

author: e100
author_rank: Frequent Contributor
timestamp: May 24, 2017, 03:45:19 pm
content: When I looked at electric bike conversion kits a couple of years ago it seemed like everyone was using LiFePO4 batteries. These are essentially non-flammable (unlike the LiCoO2 battery typically used in mobile phones), so storing and charging a large bike battery in your house or workplace was unlikely to set it on fire.However, since then things have changed. It looks like LiFePO4 is being displaced by LiNiMnCoO2 (NMC) batteries.I tried searching for information about the safety of these types of battery but couldn't find much.Can anyone comment on the failure modes of this type of cell and whether they contain a flammable electrolyte or solid?

author: MagicSmoker
author_rank: Super Contributor
timestamp: May 25, 2017, 11:31:43 am
content: The solvent for the electrolyte in all lithium ion chemistries is a combination of various carbonate esters which are themselves very flammable, unlike pretty much every other type of battery chemistry in which water is the solvent for the electrolyte.The reason LFP (LiFePO4) is considered (relatively) safe is because it is practically immune to auto-ignition from thermal runaway, while LCO is inordinately prone to it; NMC and NCA are in between those two extremes, though closer to the LFP end of the scale. Note, however, that LFP still has a considerable advantage in both charge and discharge rate compared to all the other Li-ion cell types except the rather rare Titanate kind. That may or may not be relevant in an electric bike application - a 500W drive system with a 48V/10Ah battery will only be stressed at a little over 1C, and the typical NMC or NCA cell can handle at least a 2C discharge (the >10C discharge rating of a LFP cell is hardly an advantage, then, as I imagine an e-bike that can only run for 6 minutes wouldn't be a big seller).

author: exmadscientist
author_rank: Frequent Contributor
timestamp: May 26, 2017, 05:17:47 am
content: It's a few years old now, butthis NREL reporthas more information than you could ever want on lithium-ion chemistries. Short version: yep, they're flammable... but so are all the others.

author: grifftech
author_rank: Frequent Contributor
timestamp: May 26, 2017, 04:55:52 pm
content: Quote from: MagicSmoker on May 25, 2017, 11:31:43 amone that only takes 6 minutes to charge would be
Non-functioning oscilloscope?  - Page 1
Forum section: electronics / beginners

author: patrickwang
author_rank: Newbie
timestamp: October 26, 2017, 02:24:32 am
content: Hi, I recently bought a Tek 2225 scope on eBay. The screen produces a trace and can display both channels at the same time. But when I hooked it up to my function generator, it does not produce a trace whatsoever. What are some troubleshooting steps I can take or should I just return it?Thanks

author: ataradov
author_rank: Super Contributor
timestamp: October 26, 2017, 02:36:58 am
content: Check that you have coupling in DC position first. If this is the case, then only disassembly and inspection will tell.

author: BrianHG
author_rank: Super Contributor
timestamp: October 26, 2017, 02:53:02 am
content: set your vertical resolution to it's largest volt/div setting and slow down your horizontal time base.

author: tggzzz
author_rank: Super Contributor
timestamp: October 26, 2017, 08:31:46 am
content: If this is your first scope, read the operators manual to understand the effects of the controls.http://w140.com/tek_2225_op_and_opt.pdf

author: danadak
author_rank: Super Contributor
timestamp: October 26, 2017, 10:50:17 am
content: Set scope to page 4-1, 4-2 settings, trigger to auto, trigger source to INT (internal), vertical to AC.http://w140.com/Oscope_Tek2235-op.pdfRegards, Dana.

author: Shock
author_rank: Super Contributor
timestamp: October 26, 2017, 07:20:00 pm
content: Try the inbuilt probe adjustment signal. It's just to the left of the trigger BNC socket. But as people mentioned, an analog oscilloscope requires familiarity with the oscilloscope to manually setup the trigger, coupling, horizontal/vertical etc properly.Try both channels, you might also want to check your probe as well and swap it if you have two, or test with a multimeter.

author: james_s
author_rank: Super Contributor
timestamp: October 27, 2017, 08:52:38 pm
content: The first thing to do is make sure you know how to properly use it. I'm not trying to suggest you don't, but more than once people have brought me "broken" scopes that in fact worked just fine, they just didn't know how to operate it.
Non-inverting Op-amp Comparator with Hysteresis - Page 1
Forum section: electronics / beginners

author: Jwillis
author_rank: Super Contributor
timestamp: January 27, 2020, 07:49:25 am
content: How do I work out the Hysteresis of a comparator with a dynamic reference ?Do I just take an arbitrary reference voltage within the range I'm using and work it out from that? I'm not sure if the Vth (High Threshold Voltage) and Vtl (Low Threshold Voltage) should move up and down with the reference.

author: David Hess
author_rank: Super Contributor
timestamp: January 27, 2020, 10:16:02 am
content: The hysteresis is independent of the reference voltage unless specifically designed otherwise. Usually it only depends on the output voltage swing and divider ratio.
Non linearity of the single stage grounded emitter amplifier - Page 1
Forum section: electronics / beginners

author: bob7185
author_rank: Contributor
timestamp: December 02, 2019, 02:16:20 am
content: Hi, everyone I've been going over the basics reading the AoE 3rd edition by HH. I am currently reading about the Shortcomings of the single-stage grounded emitter amplifier precisely their non linearity . I m kinda lost in that part where the authors say:"... Because this represents the extreme variation of gain (i.e., at the peaks of the swing), the overall waveform “distortion” (usually stated as the amplitudeof the residual waveform after subtraction of the strictly linear component) will be smaller by roughly a factor of 3.". Where does that 3 come from ? How did they derive it ? If somebody can please help with that doubt.

author: magic
author_rank: Super Contributor
timestamp: December 02, 2019, 08:41:26 am
content: Kinda impossible to answer without more context or the same book that you are reading

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 02, 2019, 09:38:34 am
content: It's on page 94.They're referring to the peak change in gain. The error averaged over a full waveform is smaller, by about that much.For example, suppose the output waveform were a triangle wave (rather than the "barn roof" it actually is). We know the triangle wave has harmonics with amplitudes that go as 1/N^2 (for N odd). This sums to 1.47% THD. But the peak error is .Hmm.Excuse me while I step over to the blackboard and doodle something for a moment...Ah, the closest sine wave to a triangle wave is 0.81246152 amplitude (best fit, 100 samples evenly spaced). That is, for a triangle of peak amplitude 1 and a sine of peak 0.81..., the RMS error is minimal.In this case, the peak error is 18.7% while the RMS is 7%, which is, very approximately, the factor of 3 mentioned.Crude demo:https://docs.google.com/spreadsheets/d/1gBjter_vGnuW1iC6h7usQKf3WjN0YbGgO2lV13uEJVE/edit?usp=sharingYou may also find this helpful for seeing how such a calculation can be done?If one were to input an exponential waveform instead of a linear ramp (of some given amplitude, because again, the distortion of an exponential is proportional to its amplitude), they'd get closer to the result H&H got. The waveform is peakier (a poorer fit to a sine), so the peak-to-RMS error can be expected to be higher, probably above 3 for the amplitude pictured.(Ed: didn't really have to go and write a spreadsheet for that. It's sufficient to note that the harmonics are orthogonal; the RMS test is equivalent to an inner product and the inner product of fundamental with any harmonic is zero. So the "best fit" of course has to be the ratio of the triangle's fundamental amplitude, or 8/pi^2 ~= 0.81. Not that these terms are probably meaningful to the beginner!)Tim
non polarised capacitors - Page 1
Forum section: electronics / beginners

author: M0BSW
author_rank: Frequent Contributor
timestamp: February 02, 2014, 08:08:32 pm
content: Hi, I need a non polarised electrolytic capacitor, and I'm in a bit of a pinch, I remember that there is a way of wiring two polarised caps to make a no polarised cap, but I can't for the life of me remember how to do it , can anyone help.

author: SeanB
author_rank: Super Contributor
timestamp: February 02, 2014, 08:10:55 pm
content: Back to back in series same value.

author: M0BSW
author_rank: Frequent Contributor
timestamp: February 02, 2014, 08:24:47 pm
content: Quote from: SeanB on February 02, 2014, 08:10:55 pmIt is just to try something out , before buying a non polarised cap, as the thought of one of them degrading wouldn't be good.

author: The Electrician
author_rank: Frequent Contributor
timestamp: February 03, 2014, 12:21:12 am
content: What's the application? Will the voltage across the NP cap have a substantial DC component for any length of time?

author: M0BSW
author_rank: Frequent Contributor
timestamp: February 03, 2014, 07:37:16 am
content: Quote from: M0BSW on February 02, 2014, 08:24:47 pmI don't think so, I'm using them as a part of a noise filter at the speaker end on a receiver. the output is around 3 watts into a 8ohm speaker. This is the basic circuit.

author: Mr Smiley
author_rank: Frequent Contributor
timestamp: February 06, 2014, 03:03:27 am
content: From a pdf document i got some from where i can't rememter"If two, same-value, aluminum electrolytic capacitors areconnected in series, back-to-back with the positive termi-nals or the negative terminals connected, the resulting sin-gle capacitor is a non-polar capacitor with half the capaci-tance to either of the original pair. The two capacitors recti-fy the applied voltage and act as if they had been bypassedby diodes. When voltage is applied, the correct-polaritycapacitor gets the full voltage."