hybridfree/eevblog-posts huggingface dataset:
Nissan Diagnostic tool - Data Cartridge  - Page 1
Forum section: electronics / projects

author: Cozzmo
author_rank: Regular Contributor
timestamp: October 07, 2019, 05:52:13 am
content: Thought i'd share with you something interesting i found today. I recently got a Nissan Consult Diagnostic unit, not the eBay $10 one, the original real deal Nissan Dealer gear for Pre-2000 vehicles. It uses a PCMCIA card size cartridges with a 1x38 pin interface (instead of the 2x34 pin for PCMCIA) and when opened up, it reveals some exposed die storage attached directly to the PCB with bond wires and all visible (and not encapsulated at all). Beautiful ! Literally held together with very thin double sided tape.In time i'd like to extract the data from the card(s) to be able to provide a resource to other enthusiasts as these cards are hard to get, and the later versions / updates are even harder to get and often very very expensive. Depending on the features and the year model of the car it may require a specific card for certain diagnostics. Very interesting (to me at least).
Nissan Leaf Battery Pack Charge Information - Page 1
Forum section: electronics / projects

author: IpigiEpos
author_rank: Newbie
timestamp: June 26, 2021, 03:25:24 am
content: I recently purchased 2 Nissan Leaf (2015) battery packs and set them up in a 4S configuration. The MPPT charger (Renogy Rover 20A) I use allows for custom user setting. I'm trying to confirm some of the information that I found online as very little seems available.Does anyone have any information that they could contribute to know how to charge Nissan Leaf Batteries? Specifically, can anyone suggest what charger settings I should use for charging? Assuming the information below is correct, I am looking to charge at around 85% SOC and discharge no more than 20% SOC in order to extend the number of cycles the battery can hold a good charge at. Right now the battery is connected to a BMS that supports this voltage range for a 4S configuration.Information I have so far (collected from various sources online - may not be accurate)Type : Lithium-ion - Laminate TypeCathode/Anode Material: LiMn2O4 with LiNiO2/GraphiteCell Max Charge : 4.2vCall Min Discharge : 2.5vEach Pack comes in a "2S" configuration (8.4v Max, 5v Min, 7.6v Nominal)Nissan Charge Information (from a youtube video) - unclear if these are Nissan Charging parameters or the actual cell charge values:100% 4.1v95% 4.075v90% 4.05v80% 4.0v65% 3.925v50% 3.85v30% 3.75v20% 3.7v15% 3.675v10% 3.65v7% 3.635v0% 3.6v

author: Siwastaja
author_rank: Super Contributor
timestamp: June 26, 2021, 09:57:02 am
content: Don't know about the Nissan's LMO chemistry exactly but I'm 99% sure 0% isn't at 3.6V. This would be roughly 45% and at the best long-term cycling range, don't leave it unused.For long-term cycling, I'd prefer leaving 25-30% unused on the top and maybe 15-20% on the bottom. Storing and cycling at top means electrolyte reactions and lithium plating. Cycling at very bottom means, AFAIK, increased heating (due to higher DC ESR near bottom) and back-and-forth "swelling" of the lattice. 20-70 is a good range to stay within. In voltage, this would be very roughly, what, maybe 3.5V to 3.95V.I'm assuming you are using low charge/discharge rates (say, below C/5) in such large solar storage system which makes voltage-based SoC estimation a breeze so you can ignore complex and error-prone charge intergrators. You can characterize one cell yourself, just slowly discharge into constant current load, record voltage and record charge integral. Do the same charging back. If charge / discharge currents are near zero (i.e., test is very long), the two curves are nearly identical. The larger the charge/discharge current, the more apart the curves become. For a generic SoC estimation curve, take the average of the two at each point.Everyday charge to 4.0, occasionally / if needed charge up to 4.2V. Under negligibly low load, discharge down to maybe 3.4V, but under heavy load say C/2 you can go down to 2.5V usually. This is because the DC resistance of the cell rises near empty, making the U=I^2*R drop of the cell higher.
NIST getting into IC design for R&D... - Page 1
Forum section: electronics / projects

author: Bud
author_rank: Super Contributor
timestamp: September 21, 2022, 09:22:12 pm
content: ...and Google pays for it...https://www.ept.ca/2022/09/nist-google-to-form-supply-of-chips-for-researchers-startups/
Nixie Holder - Page 1
Forum section: electronics / projects

author: veedub565
author_rank: Frequent Contributor
timestamp: April 23, 2020, 09:32:18 am
content: I'm looking for a suitable holder for a Mullard ZM1175 NixeSomething like this would dohttps://www.google.com/search?q=nixie+holder&bih=937&biw=1920&rlz=1C1GCEB_enGB893GB893&hl=en-US&tbm=isch&source=iu&ictx=1&fir=NBM8gL9wlAgi6M%253A%252C0Ndcc9EFsCnsiM%252C_&vet=1&usg=AI4_-kQPlaiLJbfPi3OFYcwemjuDb40CsA&sa=X&ved=2ahUKEwj1m6_Knf7oAhXy-ioKHX9ZAPoQ9QEwAXoECAoQGA#imgrc=NBM8gL9wlAgi6M:Any suggestions ?
Nixie Tube Decimal Point Question - Page 1
Forum section: electronics / projects

author: BHyman
author_rank: Newbie
timestamp: May 31, 2021, 07:55:57 pm
content: Hello everyoneI've been working on a project that is making a clock using IN-14 nixie tubes, 74HC595 shift registers, 74141 nixie tube drivers, a RTC, and an Arduino Nano. I was able to wire up one tube to test some code and get a feel for how they work. I used a 10k resistor (I know the schematic says 68k) with a 170V power supply to power it.My question is about the decimal point on the tubes. I know on the datasheet it says that the current for it is lower than the normal digits, so I need an additional resistor. Would this resistor go in between the transistor driving that decimal point and the cathode for it, or somewhere else? Do I also need resistors in between the arduino and transistors? Also, how do I figure out the value for the resistors? I've attached a picture of my schematic that I made in KiCAD for this. This is my first attempt at trying to do a project like this and I would really appreciate any advice. Thank you!

author: oPossum
author_rank: Super Contributor
timestamp: May 31, 2021, 08:10:33 pm
content: All that is needed is a resistor between the emitter and ground. Connect the base directly to the MCU and the collector directly to the nixie. This is a crude switched current sink. The current will be approximately 4 / R. So a 22k resistor would be approximately 180 microamps.

author: BHyman
author_rank: Newbie
timestamp: May 31, 2021, 10:12:12 pm
content: Thanks for the quick and detailed response. If you don't mind me asking, where does the 4 in the calculation come from?

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 31, 2021, 11:29:12 pm
content: Quote from: BHyman on May 31, 2021, 10:12:12 pmI interpreted it as 5V - 0.7V Vbe drop which gives about 4V.

author: profdc9
author_rank: Frequent Contributor
timestamp: June 01, 2021, 02:47:21 am
content: I used a 10k resistor for the digits and a 22k resistor for the decimal points.I would consider multiplexing the digits. You will need far fewer signals. I did a very similar projecthttp://www.github.com/profdc9/NixieClockwhere I multiplexed the digits.
nixie tube speedometer - Page 1
Forum section: electronics / projects

author: Add_man
author_rank: Newbie
timestamp: August 30, 2017, 04:17:49 am
content: So ok, I have this somewhat unusual idea of adding an auxiliary nixie tube speedometer display to my car.( i would keep the old one in place.)I was thinking of using the small in-17 tubes and powering the HV board off the 12v car supply. while controlling them using a simple microcontroller. and would used a pass through speed sensor to capture the speed data.but... my car gas tanks right next to the dash (like within a foot of each other and within the same compartment) and I'm worried about 10.5 gals of gasoline sitting, sloshing and venting next to 170v (although it is low amps). Do you'all know if this would pose a risk? or would this be a fireball death trap?
NKR K1000 Mini 2-Channel Audio Switch/Mixer Modification - Page 1
Forum section: electronics / projects

author: Lalbert
author_rank: Newbie
timestamp: November 05, 2017, 07:09:35 am
content: Recently I bought a NKR (Not Kwite Right!) model K1000 "mini 2-channel audio mixer" from a supplier on AliExpress (under AU$30 incl. post), only to discover that it does not function as a mixer at all, but rather as a 2-channel audio switch! On the plus side, it has a pair of digital echo processors (no mention of this in the ad or product spec's) and a headphone output with its own volume control. Also, the ad on AliExpress implied it connects to a mobile phone via USB! I pulled the thing apart and reverse-engineered it to see if it could be modified to function as a mixer.Sure enough, there were some missing resistors which, if fitted, might make it work as a mixer, but I suspect not optimally. I devised a simple modification to make the device function properly as a mixer and to use the echo processor more effectively. Contact me if you would like to see the schematic and details of the mod. To find the product on eBay or Aliexpress, use the keywords "mini sound mixer K1000". By the way, there is no USB connectivity... the USB socket is used solely for charging the battery.
NMOS as high side pass transistor to drive LEDs? - Page 1
Forum section: electronics / projects

author: llkiwi2006
author_rank: Regular Contributor
timestamp: January 21, 2018, 02:04:22 am
content: Hi,I recently came upon a circuit that drives 60 leds in parallel (at a maximum of 1-2mA each) with a pwm signal from a microcontroller, but it does switching on the high side with a n-channel mosfet. The pwm signal is a 0-5V logic signal, and the mosfet is fed with a 5V drain voltage, so the mosfet ends up dropping around 1.5V, heating up to around 50 degrees C.My questions is why have they done this? Since they are already using resistors to limit the current to each led, why not just use bigger value resistors and a p-channel mosfet (or do low side switching) instead, so heat is not dissipated in the mosfet?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2018, 02:37:06 am
content: Quote from: llkiwi2006 on January 21, 2018, 02:04:22 amProbably because they were not smart. Never attribute to intent, what can be reasonably attributed to stupidity (to paraphrase).The circuit still works if "PWM" is more than 5V; 10V would be good. This can be better than using PMOS, because NMOS performs 2-3 times better. In this case, the added logic would probably be worse, but it's an important tradeoff at higher power levels.If the LEDs don't need to be common to ground, they're better placed in the drain circuit (hanging off +5V), in which case an NMOS is just fine.The PWM signal does need to be inverted, for a common source switch (of either polarity). Probably a trivial software change (or add an inverter).Tim

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 21, 2018, 03:10:10 am
content: I would not be so quick to attribute this to stupidity given that we know nothing beyond the redrawn schematic.Driving a common source vs. a common drain (source follower) results in different dynamics. Is the difference important?Was this a BOM issue (pch vs. nch, small resistor vs. larger resistor)?

author: David Hess
author_rank: Super Contributor
timestamp: January 21, 2018, 04:35:51 am
content: They either did not know any better or wanted to save the 20 extra cents that a p-channel MOSFET would cost over an n-channel MOSFET. A PNP transistor would have worked and been less expensive.
NMOS inverting amp with negative VDD? - Page 1
Forum section: electronics / projects

author: Chad1
author_rank: Contributor
timestamp: June 21, 2012, 09:50:52 pm
content: Hi guys,I'm trying to design a circuit using only an N-FET and a resistor that performs with the basic inverting amp characteristics, but I want it to work with both a + and - VDD. Any suggestions? I'm sure this spec will require more components than an N-FET and a resistor. I tried to come up with a circuit that introduces a diode in series with GND so that when Vin (gate) is pulled low, Vout is VDD (where VDD<0). Below is a truth table of what I want (the last line is the only one that is a problem):Vin (VDD>0) Vin (VDD<0) Vout------------------------------------------------------high 0low VDD (>0)high 0low VDD (<0)VDD||/\/R \||-----o----------o VoutVin ----|-----|||GNDThanks a lot!
No link on Wiznet W5200 - Page 1
Forum section: electronics / projects

author: daniel19210
author_rank: Contributor
timestamp: July 21, 2013, 07:55:28 pm
content: Hi!I'm working on a simple project which uses Wiznets W5200 ethernet chip. Communication between w5200 and main microcontroller works fine but there is no link between w5200 and the router. I based my schematics on those found in w5200 and hx1188 (ethernet trafo) datasheets. Did I do something wrong? Are traces too long/thin or something? I would appreciate any help as I'm really desperate right now. Thanks!Schematics and board layout for ethernet part are attached below.

author: MagicSmoker
author_rank: Super Contributor
timestamp: July 28, 2013, 06:15:27 pm
content: It looks like you didn't connect the transformer center taps on the PHY side to your 3v3 analog supply, but you did connect some lines on the RJ45 jack to 12V, which is a risky thing to do (the PoE standard, if used, specifies a nominal 48V supply).Your layout isn't ideal for ethernet, but that is something to tackle after correcting the above mistake. And since you have to redo the board anyway, I also strongly suggest using an ethernet jack with integrated magnetics (usually called a "magjack")Finally, you should try to copy as much from the reference design as you can:http://www.wiznet.co.kr/Sub_Modules/kr/product/product_detail.asp?Refid=643&page=1&cate1=&cate2=&cate3=&pid=1143&cType=2Hope this helps - I used the similar W5100 to give ethernet connectivity to a product I designed a few years ago and it was not a particularly well-polished chip. These days I use microcontrollers with built-in MACs and inexpensive external PHYs like SMSC's LAN8720, thereby avoiding the whole dodgy/kludgy MAC/PHY combo chips like the Wiznet W5200 or Microchip's ENC28J60.
No-name class D amp board - disable headphone jack sensing? - Page 1
Forum section: electronics / projects

author: mtin
author_rank: Newbie
timestamp: July 26, 2025, 02:21:50 pm
content: Hi! I am building a little project, a wearable vest with bass shakers in it. I got some cheap class D amplifiers to power this, as they had integrated bluetooth, 100W output, AND, important for my project, a headphone out. I planned to "daisy chain" these, so one gets an audio signal, powers 2 shakers, passes the signal on to another one which then again passes the signal on to actual headphones that you wear. End result should be kinda silent disco but with heavy body bass feeling.Problem is: the headphone jacks have sensing built in which disables the amplifier once you connect something to the Aux Out. It's not the mechanical switch of the jack, the sensing happens way before when I start connecting a cable it cuts off the main speakers. When I push it in even further, then the headphones come on.Do you think there is any chance to trick the board into allowing both amplified speaker output _and_ headphone output? Any ideas would really save my project. Last resort would be to get an active headphone amplifier and put it infront - but that's more devices to power (off power banks) and more electronics and cables in general.I bought these boards:https://www.amazon.de/dp/B095NYYJ9MAny help greatly appreciated!! ❤️

author: themadhippy
author_rank: Super Contributor
timestamp: July 26, 2025, 02:34:06 pm
content: id try bodging a wire or 3 onto the connections from the jack to the pcb

author: themadhippy
author_rank: Super Contributor
timestamp: July 26, 2025, 03:22:46 pm
content: Quoteand have very quiet speakers

author: Buriedcode
author_rank: Super Contributor
timestamp: July 26, 2025, 10:13:48 pm
content: That jack has a switched contact for the tip, but it looks to be a 4 pole socket - tip, ring, ring2, and sleeve.A common way to sense a stereo plug being plugged in is to check for continuity between the sleeve, and ring2 - the 4th pole, since a stereo plug will short those two.A quick way to check is to look at the connections to the jack - audio will most likely go to ceramic caps, the ground connection will go to local ground, where-as a switched contact will most likely have a resistor pull-up, and go to an IO on the IC directly.
No NEC Blues - Page 1
Forum section: electronics / projects

author: Helmanfrow
author_rank: Contributor
timestamp: July 09, 2020, 08:05:04 pm
content: I have a Sony GP5 guitar effects processor from the early 2000's which is no longer passing signal.One one clear symptom is that the front LCD screen lights up but displays no characters.Another is a loud, high-pitched whine which sounds like it's coming from a component labeled NEL-D32-46. I've looked it up and it appears to be a NEC voltage inverter for the LCD panel. Coincidence? I think not.I can't be certain that this component is the reason for the general failure but it seems like a good place to start so I figure it's worth swapping out.Problem is that the component seems to have been discontinued ages ago and I don't know how to track down NOS or pin-equivalent replacements.Anyone know where I can find these?

author: Renate
author_rank: Super Contributor
timestamp: July 09, 2020, 08:12:23 pm
content: Is that thing dragging down the +5V?That's the first thing that I'd check.Does this box pass audio by default when turned on?I'd just remove the inverter and see if the audio works.

author: themadhippy
author_rank: Super Contributor
timestamp: July 09, 2020, 08:21:55 pm
content: Quotedo you meen NEL-D32-46?not cheaphttps://www.radwell.co.uk/en-GB/Buy/NEC/NEC/NEL-D32-46/?redirect=true

author: Helmanfrow
author_rank: Contributor
timestamp: July 09, 2020, 08:39:58 pm
content: Quote from: themadhippy on July 09, 2020, 08:21:55 pmYes, that was a typo; corrected.Quote from: themadhippy on July 09, 2020, 08:21:55 pmYeah, I saw that listing and was hoping it was not representative of the if-you-know-where-to-look rate.

author: Helmanfrow
author_rank: Contributor
timestamp: July 09, 2020, 08:47:17 pm
content: Quote from: Renate on July 09, 2020, 08:12:23 pmI'll locate and check the 5v rail and report back. I just need to order a new DMM (Topic of my next post).It's been a lo-o-ong time since I've used this thing so I don't remember how it operates nominally, but it very likely would be passing signal immediately upon booting up.

author: Renate
author_rank: Super Contributor
timestamp: July 09, 2020, 09:53:47 pm
content: Oh, and check the backup battery there.If it's dead-dead it could be killing everything too.

author: Helmanfrow
author_rank: Contributor
timestamp: July 09, 2020, 11:55:19 pm
content: Quote from: Renate on July 09, 2020, 09:53:47 pmYeah... the battery is tack-welded in place.I'll need to snip it out and affix a button cell holder.
No regulator - Page 1
Forum section: electronics / projects

author: brownt
author_rank: Regular Contributor
timestamp: August 07, 2018, 10:41:29 pm
content: what happens if I was to run a project on batteries without a regulator.A microcontroller, a digital pot and a few LEDsWhat sort of problems occur, or what is the disadvantage?

author: MT
author_rank: Super Contributor
timestamp: August 07, 2018, 11:07:57 pm
content: Quote from: brownt on August 07, 2018, 10:41:29 pmThe "brown out" "Power Supply Supervisor "circuitry inside MCU will keep MCU at reset or reset or shut down MCU.You basically dont do MCU design without regulator.

author: james_s
author_rank: Super Contributor
timestamp: August 07, 2018, 11:54:39 pm
content: The disadvantage is you burn out the micrcontroller if your battery voltage is higher than the max rating, or the circuit malfunctions once the batteries are only partially drained and along with erratic behavior you end up throwing out batteries that still have a lot of life left in them.

author: Ian.M
author_rank: Super Contributor
timestamp: August 08, 2018, 01:54:51 am
content: Its not impossible if all parts have a sufficient supply voltage range. e.g. Microchip have many 8 bit MCUs that have a supply voltage range extending from about 2V to 5.5V which are well suited to running from 3x AA or AAA cells or a single LiPO, as the supply voltage range includes both the fully charged voltage (and the max charging voltage for the LiPO) and the commonly accepted fully discharged voltage of 2.4V (0.8V per cell) for the 3x AA or AAA batteries, and 3.0V for the LiPO.However driving LEDs without excessive brightness change as the battery discharges can be difficult, and its also more difficult to use analog sensors etc. when you don't have a fixed supply voltage.One viable strategy is to use a high efficiency boost regulator IC to boost to 5.0V, when running, avoiding the common variable supply voltage issues, and shut it down in sleep mode so the MCU gets Vbatt less one Schottky diode drop to maintain its state, + gate power to other parts of the circuit that don't need to be powered in sleep using P-MOSFETs.

author: james_s
author_rank: Super Contributor
timestamp: August 08, 2018, 03:52:22 am
content: Battery powered gear with no regulator used to be very common back in the days of CMOS logic. The widely used TMS1000 and related microcontrollers typically ran directly off a 9V battery. Not much advantage anymore though, efficient switching regulators are cheap and compact.
"No RSENSE" sensing Linear Technology - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: January 18, 2021, 11:25:10 am
content: Is there a general write-up anywhere on this? The LTC3873 data-sheet saysQuote

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 18, 2021, 03:47:36 pm
content: What confuses you that is not enough in the datasheet?A transistor in the open state is also a small resistance resistor like a shunt. It is not necessary to measure the voltage drop on the low-resistance shunt-external resistor, you can perform this measurement on the transistor junction. However, the shunt resistance is normalized and has a certain value, has an accuracy class. The junction resistance of the transistor is normalized very roughly, it can vary significantly in neighboring instances, it depends strongly on the temperature and the level of the control voltage - this is an inaccurate measurement, it is more suitable for short-circuit protection or current limitation, which is used in the LTC3873.

author: 741
author_rank: Frequent Contributor
timestamp: January 18, 2021, 04:17:45 pm
content: Ah, OK so a fairly wide tolerance on RDS is fine.Thanks!

author: Andree Henkel
author_rank: Regular Contributor
timestamp: January 18, 2021, 04:48:46 pm
content: well, datasheet text could have been written more clearly:to a conventional sensing resistorin series tothe source of the power Mosfet
No Shielded Box? - Page 1
Forum section: electronics / projects

author: moffy
author_rank: Super Contributor
timestamp: June 19, 2023, 02:57:27 am
content: This is trivial, but also useful enough to share. I have been doing some very low level noise measurements and the circuit needed some shielding, both emf and thermal. So not having a suitable box I wrapped the board in gaffer tape then alfoil and grounded the alfoil. It was surprisingly effective. But after doing this a couple of times I realised I could apply the gaffer tape to one side of the alfoil then wrap the board in the composite blanket, gaffer tape towards the board. I will now keep my shielded blanket for future projects ugly as it is. Perhaps others have similar or better ways to shield a circuit when no suitable box is available? The board in question did have a ground plane.

author: TimFox
author_rank: Super Contributor
timestamp: June 19, 2023, 03:06:17 am
content: I don't have a photo handy, but years ago I built a test box using two aluminum cake pans.Mine was fancy, using hinges along one edge and a large rectangular cutout that I covered with a multiple connector plate (in case I needed a different set of connectors).My first plate had several BNC feedthroughs and several binding posts for power connections.The pans already had flanges around the open end, so I used clips around the boxes to hold them together.

author: moffy
author_rank: Super Contributor
timestamp: June 19, 2023, 03:17:49 am
content: Quote from: TimFox on June 19, 2023, 03:06:17 amThat sounds really cool, I would have loved to have seen a photo of you baking a circuit.
No worries keyfob - Page 1
Forum section: electronics / projects

author: bitluni
author_rank: Contributor
timestamp: December 03, 2013, 06:13:26 pm
content: Heyho,have another mini project readyNever search your keys again! just check out the vid for all the details how it's build.http://youtu.be/0L-zfQSA9tcI know it's not perfect since I could build it even smaller by programming the CC2540 directly... but this it's just a simple showcase.For more background on the modules I am using check out the complete playlist:https://www.youtube.com/playlist?list=PLjUbKCHhzPEy5dh0gXNUEl3-JLvPpUt2qThe project code can be found on my page:http://lab.bitluni.net/keyfobAs soon I get some hand on an android 4.3 device I will implement an app that replaces the remote.
nodemcu + sparkfun micro oled display issue - Page 1
Forum section: electronics / projects

author: uranium235
author_rank: Contributor
timestamp: October 23, 2016, 08:45:04 am
content: I'm having some problem with the NodeMCU and themicro oled display breakout board from sparkfun,everything works but i noticed that i does not display any text at all, i tried this with the sample code that they provide.Another problem is that in the demo code this partCode:void pixelExample(){printTitle("Pixels", 1);for (int i=0; i<512; i++){oled.pixel(random(oled.getLCDWidth()), random(oled.getLCDHeight()));oled.display();}}causes the nodeMCU to display this message on the serial portQuoteI'm using arduino IDE to write the code for nodeMCU, and the NodeMCU and the oled display is connected via SPI.
Noise cancelling headphones - Page 1
Forum section: electronics / projects

author: polli
author_rank: Contributor
timestamp: October 02, 2017, 02:02:55 pm
content: Hi!Please do not help me, do not give me advice, do not tell me what I'm doing wrong!To make this a bit more interesting, I'm not going to look at any tutorial, guide or book about anything anywhere close acoustical engineering. It might be worth it, as I might learn something about solving problems in general, when help might not be present.This is my first project I'm doing, in parallel with the MIDI controller thing I already posted about. I'm using this thread as a project log, so I can laugh at my mistakes when I'm done, and I guess you can already laugh now? :PI'm making some active noise cancellation headphones. This is going to be an horrible looking contraption, but I hope that it will work just as well, if not better, than what I would be able to buy for ~50$.Here is my tentative component list:* the smallest MCU that has an ADC and DAC at >=12bit, at least 48khz sampling rate, 32 bit FPU and let's say around 1 MFLOPs at 32 bit.* a couple of cheap headphones/earphones. Since the microphone is probably going to give me a pretty different signal depending on how it's positioned, I'll mark its place and orientation on my skin, and tape it there as accurately as possible, while using the earphones/headphones I can consistently position in the same way.* some kind of weird audio circuitry I know nothing about and will have to learn while I make the project! I think the microphone will have both a positive and negative voltage, while I think the ADCs I heard about - for instance in Arduino boards - only measure from 0V up. I'll also need some kind of amplifier, since I might not have a lot of bit depth to play with.Another fun part about this is that most of the things I'm about to make - evolving an IIR filter using myself as a fitness function, for example - I only understand conceptually and have never made. I know what's an IIR, but I've never coded one, not even using a filter cookbook, and I don't understand any DSP math.I hope to post an update soon.
noise coupling through a BJT transistor base? - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: April 13, 2014, 01:16:00 am
content: So if I am using a 2n2222 as a low side switch from a filtered supply, how much junk will go through the capacitor into my load?Am I correct in assuming that the parasitic base-collector capacitance is the main problem (how noise gets in).This is for driving relays. I don't know if I should have a individual filter for each relay or if I can use a low side switch and use only one filter.

author: c4757p
author_rank: Super Contributor
timestamp: April 13, 2014, 01:25:54 am
content: Base!!If I needed to switch relays from a low-noise circuit, I'd either 1) find a way to switch them while signal stuff isn't being done, or 2) power them from an isolated supply and switch them through optocouplers.

author: SArepairman
author_rank: Frequent Contributor
timestamp: April 13, 2014, 01:31:30 am
content: Quote from: c4757p on April 13, 2014, 01:25:54 amwell their being switched through a isolator and it is just range relays. I was going to use a simple capacitance multiplier filter to power the relays, I doubt much will couple through them.its probably completely unnecessary to do so BUT i still want to know the basic theory of how noise gets in.
Noise density of a 7586 nuvistor - Page 1
Forum section: electronics / projects

author: dom0
author_rank: Super Contributor
timestamp: December 15, 2015, 10:31:17 am
content: Is there some way to estimate what sort of noise density this tube produces in a cathode follower configuration?Plate current is ~4.2 mAGrid - plate voltages is ~-63 VCathode - plate voltage is ~-60 V

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 15, 2015, 09:13:10 pm
content: Not really.Can you find a noise figure (mind over what frequency/range) or equivalent noise resistance in any datasheets?Common manufacture types typically varied quite widely on noise, something about variable quality of the cathode interface (metal to oxide, and oxide to oxide). PQ types (7586 should count) were better made and controlled, and should be expected to have less noise, but the tricky part is, aselectedGP type might have better performance than the average PQ. You might have to select from dozens or hundreds to find it, of course.So, the part to part variance should be smaller, and the average should be smaller, but the fact is, your particular device might be +/-50% of that average, or something like that.The flip side being...How would you know? If you're concerned about noise, then it must be affecting your system. And therefore you have some way to quantify it. Suck it and see -- measure it yourself. (And perhaps try a few individual tubes and see how each one does?)My offhand guess is that it'll be under 10nV/rtHz, maybe 5ish. I think I would be surprised if it were less. There will be a 1/f knee, I think somewhere in the audio range, so take that into consideration as well.Tim

author: barry14
author_rank: Regular Contributor
timestamp: December 15, 2015, 09:53:24 pm
content: I have a copy of the data sheet for the 7586 nuvistor. Although the description states that this device is capable of "low noise service", there are no noise specifications in the 7 page sheet.

author: barry14
author_rank: Regular Contributor
timestamp: December 15, 2015, 10:00:59 pm
content: There is some noise data in the following publication but it is for very high frequencies (200 MHz):http://frank.yueksel.org/other/RCA/RCA_Nuvistors_NIT140.pdf.

author: calexanian
author_rank: Super Contributor
timestamp: December 16, 2015, 04:08:06 am
content: The 7586 is not really an audio tube. Its intended use is on off applications where it remains in cutoff for long periods of time. Generally however these types of tubes have very stable emission characteristics which lend themselves to low noise. As for linearity its a craps shoot. You need to pick a operating window that satisfies your headroom and bandwidth needs. They tend to be narrow in these types of tubes, but it is doable. Follow the general rules of low noise. Solid negative feedback loop and typically if you error on the side of higher plate current, to a certain degree the noise will be lower.Just some off the cuff thoughts.
noise figure plot  - Page 1
Forum section: electronics / projects

author: snarkysparky
author_rank: Frequent Contributor
timestamp: February 21, 2018, 04:16:23 pm
content: I am interested in making an amplifier with 2SC3324 transistor. My source impedance is 2k ohm.Having trouble understanding the noise figure plot for the 1db contour at 2k ohm.Can the amplifier have a 1db noise figure for all the collector currents in my added red circle.What is the meaning of the upper curves.Thanks

author: EmmanuelFaure
author_rank: Regular Contributor
timestamp: February 21, 2018, 04:34:25 pm
content: It's a contour plot, within the region inside the 1dB contour, the noise figure is below 1dB.
Noise Function to Homemade Signal Tracer Using LM386 - Design & Questions - Page 1
Forum section: electronics / projects

author: nico_2006
author_rank: Newbie
timestamp: December 18, 2024, 09:54:54 pm
content: Hi, I am designing a signal tracer based on the frontend of a Heathkit IT-5383, using an LM386 as the power amplifier, with a gain of approximately 500 and an input impedance of 500 kΩ. I would like to add the noise function found in the Heathkit IT-12.To achieve this, I plan to add a secondary winding on a transformer that provides 120 V, rectify this voltage with a diode and a 22 µF capacitor, and then include an RC filter consisting of a 10 kΩ resistor and a 47 µF capacitor. The output of this circuit would be connected to the probe through a 68 kΩ resistor, similar to how it works in the IT-12.My question is: will the gain of the device be sufficient or excessive for this function? Do you have any other ideas on how to implement it? I am open to suggestions.
Noise in SMD resistors - Page 1
Forum section: electronics / projects

author: Pat Pending
author_rank: Regular Contributor
timestamp: October 15, 2012, 06:10:21 pm
content: Can anyone recommend good low noise SMD resistors.From what I've read, the physically bigger resistors (i.e. 1/8W leaded resistors) have better noise performance.

author: free_electron
author_rank: Super Contributor
timestamp: October 15, 2012, 07:59:29 pm
content: how low ? susumu has some really low noise smd resistors. the resistive element is a special alloy.

author: ejeffrey
author_rank: Super Contributor
timestamp: October 15, 2012, 08:35:11 pm
content: Physical size doesn't really matter, what matters is the type of resistive element, and different package styles have different options. Resistor noise is a combination of johnson noise and excess noise. Johnson noise is the same for every resistor, and only depends on R and T. Excess noise depends on the applied voltage and the type of resistor material. Wire-wound, metal film and foil resistors have negligible excess noise. Thin film resistors generally have low excess noise, but it depends on the material. Thick film and carbon composition resistors are noisy.

author: Pat Pending
author_rank: Regular Contributor
timestamp: October 15, 2012, 11:33:56 pm
content: Thanks - That's good feedback.This link explained a lot, especially after reading the comments.http://www.digikey.com/Web%20Export/Supplier%20Content/Stackpole_738/PDF/Stackpole_ThickFilmXThinFilm.pdf?redirected=1

author: free_electron
author_rank: Super Contributor
timestamp: October 16, 2012, 12:18:17 am
content: Go wathc this: it explains the noise created by the actual current lfow.http://www.susumu-usa.com/products/tf.htm

author: Pat Pending
author_rank: Regular Contributor
timestamp: October 16, 2012, 04:55:51 am
content: Thanks Free e-, that was an informative presentation, especially the slides on current noise through the bulk resistance material.Looks like thin film will have the performance I'm after.
Noise injection for magnetic in-wall mains wire tracing - Page 1
Forum section: electronics / projects

author: Axk
author_rank: Regular Contributor
timestamp: October 18, 2020, 07:11:28 pm
content: I'm thinking about something similar to what this guy made:but using a dedicated "noise-generator" instead of the CFL bulb.Is 10mA peak current at 100 KHz enough for this?I'm thinking of the following design using a 555 timer, an NPN transistor and a 5W power resistor (I will also add an input fuse) with 10mA peak current (~ 3mA average):It works in the simulation and the power dissipation on the power resistor is around 1W and 300mW on the 300K resistor so I think it should work.My only concern is if the current is enough, but I suppose at such high frequencies it should be enough to pick up with a 15mH radial inductor (the largest value my local supplier has) and an opamp?I think this should work better than electric-field based capacitive sensors in my case because I have some old wiring which presumably has places with bad insulation so I have entire walls that trigger my capacitive sensor.What do you think?

author: Axk
author_rank: Regular Contributor
timestamp: October 18, 2020, 07:21:30 pm
content: Just changed the NPN to a real transistor model in the simulation and now it doesn't switch off.Have to figure out why.Guess it could be some sort of a leakage current that's always there...

author: Axk
author_rank: Regular Contributor
timestamp: October 18, 2020, 07:32:21 pm
content: Thinking more about it I guess I need a faster transistor.

author: Benta
author_rank: Super Contributor
timestamp: October 18, 2020, 07:43:39 pm
content: I think you need to learn some basic physics first.Youtube (or whatever) is a wonderful playing ground for kooks with no clue.Inductive sensing of current running through a wire that's perpendicular to the end of a coil won't fly. What this guy's actually sensing is capacitive coupling into the windings of the coil.That can be done done much easier by just holding an electrode close to the wire and amplifying the signal. Which, by the way, is how pretty much all "cable finders" work. You'll even find them integrated into hand drills etc. and they work fine.Your bad insulation would give you other problems, such as getting a shock when touching the wall. In that case you have bigger problems.

author: Axk
author_rank: Regular Contributor
timestamp: October 18, 2020, 08:47:24 pm
content: Ups, didn't think about the orientation.Do magnetic coupling based wire tracers exist then? Will it work if I orient the coil correctly or the magnetic coupling is just not strong enough?Tracing the wires is the first step to replacing them.

author: pwlps
author_rank: Frequent Contributor
timestamp: October 18, 2020, 09:50:45 pm
content: Quote from: Axk on October 18, 2020, 08:47:24 pmFound this one:https://megger.com/cable-route-tracer-accutrace

author: Axk
author_rank: Regular Contributor
timestamp: October 18, 2020, 10:13:15 pm
content: Great find, thanks!
Noise on 25mV 1Mhz sine wave wave - Page 1
Forum section: electronics / projects

author: Terabyte2007
author_rank: Frequent Contributor
timestamp: October 20, 2013, 12:39:18 pm
content: I have this random noise which I think may be related to my cable which is brand new. It is a ringing noise which does not appear to come from the equipment. I have tried to isolate any EM noise in the area which I don't think it is. I can make it come an go with just moving the cable so I thought maybe it was the connection or a cable issue. Changing cables did not help and I found that moving my arm around did change the ring and even remove it! To me this sounds like EMF interference or maybe grounding issues with the circuit. Is there good solid method to remove noise at these level (25mV and smaller)?Here are the captures:

author: awallin
author_rank: Frequent Contributor
timestamp: October 20, 2013, 01:10:45 pm
content: looks ilke noise from a switched-mode powersupply?how often does that repeat? something in the range of 50-100kHz would be typical for SMPSU.If you only need the 1 MHz then use both high- and low-pass filters around that frequency.Shielding and strategically placed ferrites might reduce that noise also.Use linear powersupplies or batteries if you really need low noise.

author: ElectroIrradiator
author_rank: Frequent Contributor
timestamp: October 20, 2013, 01:12:54 pm
content: Are we supposed to guess what you are testing?Schematic, test points and setup, please.

author: Terabyte2007
author_rank: Frequent Contributor
timestamp: October 20, 2013, 05:34:54 pm
content: Quote from: awallin on October 20, 2013, 01:10:45 pmI think you might be right with the switched-mode. Thanks.

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 20, 2013, 05:44:43 pm
content: Quote from: Terabyte2007 on October 20, 2013, 05:34:54 pmMy neighbour had a sub $1 mobile phone charger doing something like that, effectively killing my reception in the 2-20Mhz area.I told him that it was a real fire hazard so he unplugged and binned it right away...
Noise on mains supply - Page 1
Forum section: electronics / projects

author: MattHollands
author_rank: Frequent Contributor
timestamp: December 29, 2015, 08:26:27 pm
content: Hi,I built a Nixie clock a while ago, mostly following Mike's designs (http://www.electricstuff.co.uk/nixpthschem.pdf) for the 230V version (I'm in the UK). This means that it counts the 50Hz cycle of the mains supply to keep time.What I found is that when I plug the nixie clock in next to my lamp, I can turn the lamp on and off repeatedly and this causes the clock to advance time. This is due to noise created on the mains supply due to the switching of the lamp, which looks like the mains supply cycling. It normally jumps about 2 minutes at a time.I would like to suppress this noise but I'm not sure of the best way. Could anyone help me out?I thought a choke might help, but I only had one lying around the house so I tried wrapping the mains lead around it. This had no effect but I am willing to accept that this was due to the fact that it wasn't a very thought through choke.In the schematic, C5 is there to remove high frequency noise, so perhaps I could replace it with a larger capacitor.Thanks!Matt

author: AlphZeta
author_rank: Regular Contributor
timestamp: December 30, 2015, 05:46:14 pm
content: Did you try properly decouple all those counter ICs (4017)?

author: w3amd
author_rank: Regular Contributor
timestamp: December 30, 2015, 05:56:17 pm
content: Band pass filter for 40-70 Hz?

author: mij59
author_rank: Frequent Contributor
timestamp: December 30, 2015, 06:53:04 pm
content: First check the power supply rail +4V7.Switching noise could affect the set input of U8B, or the clock input of U3.Try for C5 10nF.Connect the CO output of U6 directly to the clock input of U3.
Noise rejection on 3v3 line for long runs - Page 1
Forum section: electronics / projects

author: DonnieBrodan
author_rank: Contributor
timestamp: April 04, 2021, 06:39:23 am
content: I have a microcontroller powered by 3v3, with a 3v3 sensor connected through a differential bus over cat5. If I use a long cat5 cable, I noticed my USB Hub powering it disconnects the devices on the hub. I assume this is due to connecting a giant antenna to the 3v3 line (and indirectly into the 5v USB line powering it). Is there a simple solution for this?

author: SeanB
author_rank: Super Contributor
timestamp: April 04, 2021, 09:26:21 am
content: Probably voltage drop on long lines. you probably will be better off using a 5V feed down the line, and local decoupling and regulation by the far end to feed the sensor. Extra decoupling capacitors and overvoltage protection on the connections to the long line at both ends would also be advantageous.

author: DonnieBrodan
author_rank: Contributor
timestamp: April 04, 2021, 11:32:22 am
content: Thank you, so I just noticed there are no filter caps on the main board sensor connector connecting VCC and GND. My sensor board has 100nF and 1uF caps across VCC and GND. Could it be this simple? Also sensor board has a protection diode across VCC and GND, might do well to add one to the main board... Sensor is running fine from 3v3, not sure if voltage drop alone is killing anything?

author: DonnieBrodan
author_rank: Contributor
timestamp: April 09, 2021, 06:01:42 am
content: Could potentially connect the (USB eugh) scope to the 3v3 line and the upstream 5v lines to see how they look. I could bodge a 0.1uF and a 1uF decoupling cap on the main device 3v3 connection for troubleshooting. Will likely require a new batch of PCBs once I get it figured out though.
Noise/ground loop problem with car 220v inverter and subwoofer - Page 1
Forum section: electronics / projects

author: jorgen_re
author_rank: Newbie
timestamp: July 13, 2014, 12:39:21 pm
content: I've got an 220v inverter in my car which is driving a 220v home theatre subwoofer. The output of the inverter is floating. I use a audio splitter cable to feed both my car stereo and the subwoofer with audio from my phone. When I power up the sub I can immediately hear ~100Hz humming in the sub, but it disappears when I connect the audio cable to the sub and effectively ground the sub's output to the car's chassis. However when I connect the audio cable to the sub, the humming noise manifests to the car's speakers. It is possible to drown out the hum with uncomfortably high volume.I could solve this problem easily with a dedicated car subwoofer but I don't want to spend money on one at the moment. Another thing to note is that I am feeding the whole signal to the sub with no low pass filtering. It works fine without, but an active LP-filter could both be beneficial in terms of audio quality and maybe stop the hum going the "reverse direction" back to the original car audio system?Help and suggestions is appreciated!

author: Psi
author_rank: Super Contributor
timestamp: July 13, 2014, 01:16:55 pm
content: car audio isolation transformer