hybridfree/eevblog-posts huggingface dataset:
Mechanical relationship between stator and magnets in linear BLDCs - Page 1
Forum section: electronics / projects

author: Yaroooo
author_rank: Regular Contributor
timestamp: January 10, 2020, 05:38:13 pm
content: Hello!I'm trying to understand BLDC principles on linear motion. In particular a 3-phase motor unrolled on a linear rail. I'd like to understand basic principles and create a small model to play with. Leaving "control part" out of this topic, I'm looking for tips and help to understand mechanical relationships between magnet/coil displacement and distances.Online it's possible to find something already made commercial and some basic principles with animation, but without useful parameters (maybe I've typed wrong magic words on Google). Anyway documentation and links are appreciated. I premise that I know this topic is not easy and high efficiency is reached only with EMF simulations, but at hobby level some guide lines and proportions sometimes are enough to play with.Model I'd like analyze is the one that represents rotational BLDC on a linear plane, with magnets as rotor(or mover) and coils as stators(or base). 3-phase current will drive coils and move above carriage (plate with magnets). Commonly are used 2 winding per phase and there's a (supposition) relationship of 3 coils every 2 magnets. I've tried to represent this on linear configuration in below image, in first illustration magnets are aligned with bottom coils (don't look at colors), in second one magnets are in a commutation position where 2 coils are open (black).I've found that it's hard to realize in real because coils will have a bigger footprint due winding, accordingly exposed core will have a gap between each coil. In below image I've tried to illustrate what happens. Keeping same magnet/coils width and pitch between them I'll have a gap between active coil and related magnet or a small overlap. In gap case I'll nearby nullify fems. Increasing magnets to their maximum width probably a better result is obtained, but seems that anyway overlaps are really small.This make me think that maybe a different approach is used, principle is simplified to be easy explained by actually something is different. Maybe 3coils-2magnet proportion is not respected. In facts it's a linear motor without rotational limitations so we've an open loop instead of a closed one. Can I drive coils with a 3-phase but keep a different pitch in magnets distance? Or is there something I'm missing?

author: unitedatoms
author_rank: Frequent Contributor
timestamp: January 10, 2020, 06:11:03 pm
content: Quote from: Yaroooo on January 10, 2020, 05:38:13 pmNot necessarily. Look again at rotary brush DC motor coils. The aperture is very close to 120 degrees even if the copper takes space.Edit: It looks like you have no problem with understanding the BLDC. What is you are trying to solve? Are you not liking to have cogging in the motor ? In linear motors I saw, the magnets are looking like parallelograms, so the area of intersect over displacement in not pure trapezoid as result, but somewhat more smoothed function.
Mechanical Respirator - Page 1
Forum section: electronics / projects

author: Angel Maboni
author_rank: Newbie
timestamp: May 10, 2020, 03:46:42 am
content: Hello, this is my first post here, so sorry if i dont follow a rule or something like that. I have a question. Recently i saw that Medtronic liberated the Puritan Benett 560 schemes, and i need help with it. I'm from Argentina and since all this things with COVID-19, i dont have any classes. I'm studying electronics and am currently in my last year. As a kind of "homework" my teacher gave us the mission to create from zero a mechanical respirator, i have to do a report of how i designed it,i have to put all the schemes and circuits, and all that. I downloaded all the RAR files from Medtronic page, and i gave them a look , but i dont know what could i extract from there, my goal with the ventilator is to control the oxygen flow, and one or two of that things that get in the screen. If you know anything that could help me, i'll aprecciate it a lot. Thanks and sorry for my typos.

author: Rat_Patrol
author_rank: Frequent Contributor
timestamp: May 11, 2020, 09:40:46 pm
content: I would say you first need to identify what needs to be monitored and adjusted, as well as triggers.A mechanical ventilator is more than just pushing air. The ventilator has to "breathe" based on when the patient is breathing, so you need some way to sense when the patient is at least trying to take a breath. There is actually a lot that goes into the professional models, but since this is just an "assignment", I would say take the key features you need to monitor/trigger/control and build out from there.Professional models also humidify the air. So depending on how far you want to go, you need to monitor the humidity and have a mechanism for adjusting it.This could easily be done with an Arduino, probably use a MEGA.Start with your sensors, then work out from there.

author: Angel Maboni
author_rank: Newbie
timestamp: May 11, 2020, 10:06:17 pm
content: Thanks!! I 'll start with that.
Medium voltage AC amplifier - Page 1
Forum section: electronics / projects

author: muvideo
author_rank: Frequent Contributor
timestamp: May 06, 2012, 05:18:48 pm
content: Hello,recently I got a beautiful keithley 2015, for who doesn't know it, it's a THD analyzer and a sine wave generatorpacked in a general purpose bench multimeter.I'm playing with led power supplies, the ones that I am working on are mainly single stage PFC-Flybackdesigns, 5 to 30W power. I tought to use the 2015 for measuring current's THD of these led drivers.Now I measured the THD of my mains voltage, 220V 50Hz, and it's about 2%I need an AC power supply for testing, but no luck finding something at good price here, is usa thereare some on ebay but they are too heavy to ship at reasonable cost.Here the crazy idea of the week:the 2015 internal generator measures about 0.02% distortion and it's variable in both amplitude and frequency.How much difficult would be to build an amplifier for the 2015, and using it as AC powersupply for these circuits?The goal would be something like 150-270VAC 50Hz 300mA, but would be better 85-300Vac 40 to 70Hz.Probably it will be linear and not very efficient, but i can use the 2015 to set the voltage and frequency.Also how difficult would be maintaining a low THD?Something like this as starting point:http://www.edn.com/article/474563-High_voltage_amplifier_uses_simplified_circuit.phpNaturally it will be isolated from mains by a transformer or an smps circuit, that will create the+-400V rails.All suggestions are welcome, also something like "don't waste your time and buy an AC source"but only if you can advice me what and where to searchThank you,Fabio.P.S.Don't worry, the 2015 will be subject to the usual "teardown and photo" treatment asap
MELB: Looking for PCB layout help... (CLOSED) - Page 1
Forum section: electronics / projects

author: SL4P
author_rank: Super Contributor
timestamp: March 02, 2016, 09:32:31 am
content: I have an Altium 10 schematic, which I need help to take across to a relatively simple PTH double-sided board layout (approx 100x100mm). A second very simple board hangs off the side (LEDs) (100x25mm).Will need a couple of simple footprints, and mental contribution if you're interested!Two boards, pannelize up to some convenient multiple for production.My need is quite pressing, I have gone to PCB-CART for copper in the past.Ok to pay off-book rates, do you need some beer money?PM for more conversation.

author: SL4P
author_rank: Super Contributor
timestamp: March 02, 2016, 11:52:37 pm
content: Just to advise - I have one member looking at this project over the next few days.If he's good at what he does - he'll be able to buy beer for a couple of weeks.Thanks for the replies
MELF Resistors, anyone suggest place to buy ? - Page 1
Forum section: electronics / projects

author: dashpuppy
author_rank: Regular Contributor
timestamp: February 15, 2018, 04:03:48 pm
content: I'm looking for a pile of MELF 0204 resistor values, hard to find them all in one location. Probably going to buy stock of 100-200 each value. Anyone have some good links to share other than Digikey or Mouser ?10k221ohm100k1k392ohm150ohm681ohm56.2k1.5k4.75k
MELF SOD-80 diode with numbers round body? - Page 1
Forum section: electronics / projects

author: Chris56000
author_rank: Frequent Contributor
timestamp: March 16, 2019, 11:19:47 pm
content: Hi!Just a quickie one!Does anyone know which series of MELF diodes are blackish in colour and have no band to denote cathode - just a series of small white numbers round the body at the cathode end - I've a board with a lot of '1s' and a lot of '7s' - the diodes marked '1' rectify O/P from a standard 50Hz transformer secondary, whilst the '7' marked devices are clustered around some small ferrite-core transformers!There is also one marked '6' and another marked '9'!The diodes marked '1' test like a standard small diode with a Vf abut 0.61-0.62V, the ones marked '7' test like a fast-recovery diode with a Vf about 0,48V and those marked '6' or '9' test as a schottky with Vf about 0,15V!Chris Williams

author: Chris56000
author_rank: Frequent Contributor
timestamp: March 17, 2019, 03:24:48 pm
content: Hi!The diodes I'm trying to identify are shown in the attached image!Chris Williams
MeloAudio MIDI Commander - Custom Firmware - Page 1
Forum section: electronics / projects

author: Harvs
author_rank: Super Contributor
timestamp: July 01, 2021, 07:08:09 am
content: I'm putting together a custom firmware for this MIDI footswitch I bought.Thought I'd post here incase anyone else was interested or had one and wanted to contribute.https://meloaudio.com/products/meloaudio-midi-commander-guitar-floor-multi-effects-portable-usb-midi-foot-controller-foot-switchesThe hardware's quite nice really, can't fault it for what I think is a pretty reasonable price. Nicely finished, and products in this market are typically pretty expensive for what they are. One of these is around $160 USD.Firmware that comes on the device is ok I guess for specific applications they intended. It all becomes a bit hacky for things outside of this though, and I want to do sequences of commands to configure multiple items on my pedal board with a single button.Hardware is pretty simple as one would expect. STM32F103RET, some switches, LEDs, SSD1306 OLED, and the USB & MIDI connectors. There's also an SWD header pads on one end of the board which makes debugging easy.All the hardware is basically nutted out, and there's a CubeIDE project which exercises everything (this is just code thrown in the main.c file for reversing, not intended to be an actual application yet.) High res PCB photos are in the git repo.https://github.com/harvie256/midi-commander-custom

author: Harvs
author_rank: Super Contributor
timestamp: July 01, 2021, 08:00:59 am
content: An interesting part of the PCB is the un-populated MIDI-IN Jack. The passives and protection diode is populated, needs the jack and so-5 footprint optocoupler.There's no reason this couldn't also function has a generic USB-MIDI interface.Something I'll probably do, as could be useful. By far the hardest bit will be drilling a neat hole in the powder coated case though...

author: Renate
author_rank: Super Contributor
timestamp: July 01, 2021, 03:19:42 pm
content: I can never get used to feeling my way with shoes so I use pedals barefoot (with socks).The "guitar style" stud switches are not acceptable.I have an iRig BlueBoard which has elastomeric switches.https://www.ikmultimedia.com/products/irigblueboard/I wouldn't mind owning something with a more solid case.I don't use any of the iRig software, I just get the GATT myself.I know, this is comparing apples & oranges.

author: Harvs
author_rank: Super Contributor
timestamp: July 01, 2021, 04:13:55 pm
content: I can certainly understand what you're saying. Also I find the second row of switches particularly difficult to quickly hit without smashing the first, but it seems to be a common complaint across the market.My main use case is without a computer, just using traditional midi serial. This kind of limits the market a bit more.

author: Renate
author_rank: Super Contributor
timestamp: July 01, 2021, 06:34:51 pm
content: Yeah, I can't even imagine hitting the second row.Hmm, stuff I've never thought about!https://en.wikipedia.org/wiki/Organ_shoes
Membrane keypad - Page 1
Forum section: electronics / projects

author: Oaklander
author_rank: Regular Contributor
timestamp: August 09, 2019, 07:00:15 am
content: I need a keypad for a project. I was about to use tactile switches on PCB and a graphic overlay on top. That approach would have some problems like matching the length of the switch stems just to the underside of the graphic overlay. Durability might also be poor.Now I have found out that there are reasonably priced manufacturers of membrane keypads in China. They will be more expensive than tactile switches but not by much. Membrane keypad will also be much easier for mechanical design as it only needs a flat surface to stick on. They are also said to have a lifetime of millions of key presses.Does someone have any experience on designing and ordering membrane keypads? There is almost no information found online.Who designs the technical side of the keyboard? Do I have to design the circuit or only graphics?
Membrane keypad cost - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: May 11, 2021, 09:42:14 pm
content: Hi,I am trying to get a rough idea of cost (ranges) to make a keypad membrane front panel with the specs below.At this stage I don't have design and the suppliers I contacted all ask for a design before they can quote.Can anybody provide some rough idea of cost and timescale based on your previous experiences. Obviously the specs will be different, but if you have some examples I can try to guess a rough budget.Specs:- 8 switches- 6 colours (it might qualify for full colour) and some transparent areas (LEDs and display)- 250 mm x 250 mm- waterproof (I think they all are by design?)Thank you

author: thm_w
author_rank: Super Contributor
timestamp: May 11, 2021, 10:48:47 pm
content: They are somewhat waterproof, but you should mention this in the spec and they can provide quality adhesives between the layers which will keep out moisture (eg 3M 7959). If you plan on using this outdoors. If you want real immersion waterproof, then there is more to that as well.- How many LEDs are we talking about?- What kind of switches, tactile metal dome or membrane carbon?- What connector type?- Quantity?I would mock up a quick design and send it to them, it doesnt have to be perfect.My rough guess is for ~500pc quantity you are in the $4-10 range, add $600 for NRE. You are basically using all the high end features possible.https://www.jrpanel.com/switch/buy/http://www.elecflex.com/fq.asp?detailid=9(quote with no file?)

author: ricko_uk
author_rank: Super Contributor
timestamp: May 11, 2021, 11:32:30 pm
content: Thank you thm_w,I didn't come across that company. Useful link!I can take it from there.Thank you
Membrane keypad metal dome sizes and button-press experience - Page 1
Forum section: electronics / projects

author: hcglitte
author_rank: Regular Contributor
timestamp: February 06, 2021, 03:45:04 pm
content: Hi,I would like to ask the community regarding experience with sizes for metal snap dome sizes for membrane keypads.Our current design uses 12mm snap domes. See attached pictures for how this size is defined.The customers mostly wear gloves (cold snowy conditions) when operating the buttons.We are satisfied with this metal dome size.We are now considering using another manufacturer for the membrane keypads.This manufacturer has the option of including IP67 rating.They achieve this by adding an internal gasket ring which require a 5mm edge clearance.The issue is that this mandates the use of 10mm domes to fit space for the routing.The button spacing will stay the same though.The graphical appearance of the buttons are square 12x12 mm^2 with radius corners.Currently we use pillow embossing which fits this area.The manufacturer says that the embossing is OK to stay the same size.My worries is if the button-press experience would be worse, considering that they wear gloves.I tried to press our existing buttons just a bit off center, still within the 12x12mm^2 area of course.This was not very successful. Center pressing is quite mandatory.This "discovery" makes me to think that 10mm domes should still be OK, since center pressing is what really matters anyway.I was keen to ask here if anyone has done any "research" regarding this potential issue.Thanks.
Membrane Panels - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: July 05, 2011, 01:06:06 pm
content: Does anyone have any recommendations for an Australian supplier (or a supplier who readily ships to Australia) of printed Membrane panels. I am looking for someone who can produces prototypes and small batches up to A3 dimensions for realistic prices. (Yes I am realistic and no I don't want to finance someones kid through college.)Any suggestions?

author: PeterG
author_rank: Frequent Contributor
timestamp: July 05, 2011, 02:18:01 pm
content: If anywhere, i think China will be where you will end up looking for a product like this.Regards

author: Unknown
author_rank: Unknown
timestamp: July 05, 2011, 09:57:46 pm
content: Thanks Peter you are probably right in saying China, any suggestions from there?The local suppliers I've found/used need quantity and/or cannot support the larger sizes. With prototypes it's never going to be easy. Roll out Gillard's Combustion tax and nothing will be manufactured here period.

author: PeterG
author_rank: Frequent Contributor
timestamp: July 06, 2011, 03:15:01 am
content: yeah, Gillard is hell bent on destroying whats left of Australia.I dont know of any companies in China that work with Membrane Panels but if your going to have any luck anywhere, i would bet on China.

author: Unknown
author_rank: Unknown
timestamp: July 06, 2011, 03:23:21 am
content: Your probably right. There are lots of CNC milling machines in Australia but it's cheaper and quicker for me to order custom aluminium panels from the USA, looking like this will be similar. I'll keep searching. Thanks for your reply.

author: lowimpedance
author_rank: Super Contributor
timestamp: July 06, 2011, 05:31:48 am
content: You may have already have looked at this site, (or its not what your looking for!, excuse the bum steer if its not.)Anyway useful for panel 's and labels etchttp://www.screenprocesscircuits.com.au/Good luckJohn
Memory bus termination: ultra short distance edition. - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: September 10, 2018, 04:11:12 pm
content: I am tackling the memory bus again, this time on a board designed to be tiny. The topology here is a point to point connection between an Allwinner A13 and a MT41K256M16HA DDR3 memory chip running at DDR3-1066 (The memory chip is overclocked but I am running an DDR3L chip at DDR3 voltages anyway.) I have managed to figure out a layout that is free of vias (top side wiring only) and the maximum trace length is about one centimeter. Do I still need the 24 ohm series termination resistors as specified on Allwinner reference design and Micron technical manual TN4614, or can I just ignore all of it and use whatever on-die termination Micron shipped on that chip?On a related note, does SODIMM modules usually comes with all the termination already in place?
Memory Game Simon Says - Page 1
Forum section: electronics / projects

author: corgon
author_rank: Contributor
timestamp: March 08, 2025, 05:51:25 pm
content: Here is a short video:

author: themadhippy
author_rank: Super Contributor
timestamp: March 08, 2025, 07:57:39 pm
content: will it be sold by the 1910 Fruitgum Company?

author: Amnandaoralio
author_rank: Newbie
timestamp: June 28, 2025, 08:46:34 am
content: Where can I buy this product for credibility? I think it's great!GeoGuessr
Memory mapped SPI RAM - STM32 - Page 1
Forum section: electronics / projects

author: pyrohaz
author_rank: Regular Contributor
timestamp: December 23, 2014, 12:58:26 am
content: Hey all,I've got a small SPI SRAM chip (23LC1024) that I've written a driver for and I'm wondering if there is anyway for me to use it as accessible memory by my microcontroller (STM32F0 Discovery)?I'm not actually too sure on how to word it. I mean it in the sense of the microcontroller knows about and can occupy it during compile time, it just uses my driver whenever it needs to access the RAM? I know it will be really slow but I want to know if it is possible more than anything!Thanks,

author: tonyarkles
author_rank: Regular Contributor
timestamp: December 23, 2014, 01:29:12 am
content: You're thinking of something like mmap() that you can use in Unix, right?I've got two answers, from my admittedly limited but non-nil experience with STM32:1: No. The chip itself doesn't have any native support for doing that. It's too complex and too much of a special feature.2: Sort of, if you're willing to do a little bit of extra work. What the STM32 *does* support is DMA. You could pretty easily set up a buffer (in real memory), and a set of functions called something like flash_read(int sector, void* buf), and flash_write(int sector, void* buf). These would trigger an SPI read with DMA that would copy data to/from your sector.Either way, you're not going to get mmap(), but you can get reasonably close by using some support functions that abstract away all the nitty gritty detail.

author: dannyf
author_rank: Super Contributor
timestamp: December 23, 2014, 01:43:33 am
content: QuoteThe answer is no.Your mcu isn't aware of compilation - that's a PC thing. So there is definitively no way for that to happen.Having said that, for chips that support FSMC/FMC (your F0 isn't one of them), it is doable.To use the spi sram on your chip, you have to write code to manage it.

author: pyrohaz
author_rank: Regular Contributor
timestamp: December 23, 2014, 03:01:17 am
content: Quote from: tonyarkles on December 23, 2014, 01:29:12 amYup pretty much! What I really want it to be able to access the external SPI RAM as a standard array e.g. ExternalRam = 5; or something along them lines. Obviously the Name notation is very C based but could I set the start of the external ram as a virtual address, much higher than the largest address within the STM32 and then somehow intercept whenever the processor tries to access that area of memory, with a function to get the data off the SPI chip? I'm find with blocking reads/writes to help with thread safety etc.Quote from: dannyf on December 23, 2014, 01:43:33 amI've looked into the FSMC/FMC stuff but there are SO MANY pins required and they only support parallel rams which tend (in packaged I can solder...) to be large. I've actually got the STM32F439 discovery but I'm waiting for support within CoIDE to teach myself about FMC and the LCD interface.
Memory-mapped WLAN for ARM - Page 1
Forum section: electronics / projects

author: Gall
author_rank: Frequent Contributor
timestamp: February 02, 2012, 06:47:38 pm
content: I would like to hook wlan to ARM (S3C2440). I don't want to use USB or SDIO since both are already busy for other purposes (USB has a hub). The best thing I can do is to hook a wlan module to the bus just like DM9000.Can someone please recommend a wlan module or at least a chipset? A module is better since I don't want to mess with RF stuff. My board runs Linux.
MEMS IMU: Short Term High Accuracy Estimation of Position - Page 1
Forum section: electronics / projects

author: Psycho-look
author_rank: Newbie
timestamp: January 29, 2018, 12:28:33 pm
content: Hey,I am measuring movements using an IMU with 6DOF with 3-axis acceleromter and gyroscope. But i lack a bit accuracy with my current setup. My goal is to measure short term precision in relative position, in relation to my first movement.I have to accurately measure for about 1 sec and i can calibrate for temperature and other non-optimal factors, as my data is processed after the measuring and not in real time.Currently my angular data is quite accurate, but the acceleromter data is dragging my position of limits due to the accuracy of my IMU. So here comes my initial question,Are there MEMS IMUs that have more then 16-bit resolution, it has to be capable of measuring +/- 2g or more and have a resolution/sensitivity of somewhere around 0.005mg per LSB i think. Leading to an IMU with at least 20-bits, where every bit is quite accurate, not an IMU with lots of bits and terrible accuracy. Also, it has to be quite lite and therefore ''has to be'' a MEMS IMU. In addition, the gyro has to be accurate but if the acceleromter is accurate the gyro should not be a problem i would assume, from a short time perspective. It needs to be able to run on batteries and not be to heavy, preferably already in a complete HW setup so i can use it out of the box. When it comes done to price well, accuracy > price, the main objective is not how much it cost but how good it can measure!I have to be able to measure about 0.1mm change in position for movements of about 2 - 10mm for 1 sec, in relative position.Are there any IMUs on the marked that have the capability of this kind of accuracy?Any input is highly appreciated and if I left out any essential information I can elaborate more!Hopefully there is a good answer to this, either good or bad news are appreciated!

author: Psycho-look
author_rank: Newbie
timestamp: January 29, 2018, 12:58:37 pm
content: It ''does not need to be low cost''. But if u mean IMUs in the 5 000$ + range, the cost starts to become to extensive. I do not know what people look at as low cost IMUs since the price range is so large.
MEMS MC6470 responding weird things with i2C connection. - Page 1
Forum section: electronics / projects

author: Robotec
author_rank: Contributor
timestamp: June 06, 2022, 11:43:39 am
content: Good morning everyone,I'm developing a driver to the 6-axis MC6470 to test it before including it in a new product, is a 3 axis accelerometer 3 axis magnetometer.The problem is that i'm able to configure the accelerometer part and read it back without any problem but the magnetometer doesn't work at all, Investigating more the ID registers read really weird things:for example this is from the datasheet, is supposed to read these values in the ID registers:This is what is read:Also to enable to magnetometer a power on register has to be written... ok lets do it... sent 0x80 (10000000)but its read a not active 0x00...Any idea or experience with mCube? Is my first device form them and the tech support mail doesn't even work, i bought two units and both work like this so i have discarded a faulty unit.

author: mikerj
author_rank: Super Contributor
timestamp: June 06, 2022, 01:34:22 pm
content: You are using slave address 0x4C which is only for addressing the accelerometer (with pin A5 grounded). From section 7.1 of the datasheet"The I2C device default addresses for the magnetic sensor is 0x0C."

author: Sauli
author_rank: Contributor
timestamp: June 06, 2022, 02:11:26 pm
content: For the accelerometer:"The accelerometer requires a Stop bit between I2C transactions."For the magnetometer:"In a read cycle, the I2C master writes the device ID (R/W# = 0) and register address to be read. Themaster issues aRESTARTcondition and then writes the device ID with the R/W# flag set to ‘1’. Thedevice shifts out the contents of the register address."

author: Robotec
author_rank: Contributor
timestamp: June 06, 2022, 02:20:06 pm
content: Quote from: mikerj on June 06, 2022, 01:34:22 pmcompletely right, thank you so much.working as intended now.
MEMS Microphone IM73A135V01 with ESP32? - Page 1
Forum section: electronics / projects

author: destinyawait
author_rank: Newbie
timestamp: April 03, 2024, 10:03:25 am
content: Hi,I need help regarding IM73A135V01 MEMS Microphone and how I can use it with ESP32 board. There is no Breakout board available and I am very new to even design a breakout board. It is my humble request if someone can help me out.Thank you 🙏
Memsic i2c magnetic/(compass) sensor. What am I reading here? - Page 1
Forum section: electronics / projects

author: HSPalm
author_rank: Regular Contributor
timestamp: June 22, 2011, 03:18:46 pm
content: Hi.As my first post on this forum, I decided to ask for some help. I bought thishttp://www.sureelectronics.net/goods.php?id=944magnetic sensor from Sure Electronics because it was cheap and I wanted a way to learn i2c. Now I've setup up the i2c part, it's just that I don't know what the actual output of this thing is. I successfully read all 4 registers (x msb/lsb & y msb/lsb) and bit shifted them to two 12 bit registers for output over UART. The output on the x and y axes is changing between 0~300 when I turn the sensor module, BUT WHAT IS IT TELLING ME? The datasheet of the magnetic sensor chip is herehttp://gettheworkdone.net/images/NerdKits/Projects/I2C/Compass/MEMSIC%20documentation%201172-compass/MMC2120MG.pdf, I must be missing something.Thank you!Henrik

author: armandas
author_rank: Frequent Contributor
timestamp: June 22, 2011, 04:09:49 pm
content: I haven't worked with magnetic sensors, but I would guess that you need to look at the specification table (as shown in the attached picture).From what I understand, the output is biased at 2048 counts and will change with a (typical) rate of 512 counts/gauss. If you get 0 on the output, that would imply a magnetic field of |-2048 / 512| = 4 gauss.I have no idea if this number makes any sense, and I might be totally wrong. Corrections are more than welcome!

author: HSPalm
author_rank: Regular Contributor
timestamp: June 22, 2011, 06:29:03 pm
content: You were actually not far off at all. Memsic has released several application notes regarding their magnetic sensors, I got them in a zipped file from Sure Electronics download section, which describes how to properly take measurements, calibrate and calculate your correct values. It's an interesting read, and you learn a lot about how magnetic sensors workshttp://www.sure-electronics.net/download/index.php?name=DC-SS503&type=0

author: RayJones
author_rank: Frequent Contributor
timestamp: June 22, 2011, 08:49:46 pm
content: I'd suspect you are receiving X and Y components, which when put together can create a vector.Using trigonometry (arctan2) you can then determine the angle of this vector. and hence direction?The magnitude of the vector would then be the flux density.You cannot simply use one component alone to determine the flux density.

author: Mechatrommer
author_rank: Super Contributor
timestamp: June 22, 2011, 09:08:50 pm
content: assuming you read it correctly. were you measuring earth magnetic field? i dont quite understand the question and familiar with the device. but i bought accelerometer from sureelectronics as well which will register earth g at one axis oriented downward.
Merry Christmas! PCB Christmas tree using WS2812C RGB LEDs and Attiny85. - Page 1
Forum section: electronics / projects

author: rohanwoods
author_rank: Newbie
timestamp: December 12, 2018, 05:14:15 am
content: Decided to dive head first into some PCB design and make a Christmas tree that I could give out as gifts this festive season. Pictures and video of it in action below:https://imgur.com/a/bX1Yenghttps://youtu.be/aDBNVOSA5uUOnly took me 3 revisions for a mostly finished version. Will most likely make a version that just runs off USB without a battery as this makes them quite a bit cheaper to make.The design uses 3 interlocking boards in the shape of a Christmas tree and an Attiny85 to control 22x WS2812C RGB LEDS. These are lower power (5 ma per colour) versions of the WS2812B (also known as Neopixels). The B versions end up too bright, even with the C versions I ended up running at 20% brightness). These are covered with foam dots to defuse the light. A boost converter ups the battery voltage to 5v and a charge IC takes care of battery management. I have put in the circuitry for reprogramming the Attiny from the USB port, but I have not tested it yet.Version 1 - Proof of concept, just ordered the main board. Turns out I should of listened when the datasheet for the boost controller said there is a DC path through the boost converter even when it is disabled. So it worked, it just wouldn't turn off. The whole circuit apparently runs on 3.7v without an issue.Version 2 - All three boards. Put in a mosfet to switch power on and off. Routed the battery to a pin on the Attiny for voltage monitoring, turns out it will power the entire circuit from this pin. Missed a trace that connected VCC to the last LED. Ended up getting the base board from JLCPCB completely covered in soldermask despite following the Eagle export procedure exactly from their website for all three boards.A cut trace, two mod wires (I think red mod wires look a little festive anyway) and much scraping gave a working prototype. Using the Seed Studio 2-layer export option to create gerbers from Eagle resulted in the next set of board turning out fine.Version 3 - No real mistakes, but the battery is not removable.I learnt that cheap batteries from eBay tell outrageous lies - the "2300 Mah" battery I used runs the tree for 4h20m at roughly 50ma consumption. I expected them to be a little off their quoted specs, but not by an order of magnitude!
Mesuring +50V -50V DC  - Page 1
Forum section: electronics / projects

author: imblunt
author_rank: Newbie
timestamp: April 15, 2025, 06:40:50 am
content: hey,brand new here Feel free to move if its not the right area, and im having a stupid moment.I'm trying to measure + and - 50V DC with an ads1115. I have got below what I think will work. can anyone confirm if it will?Thanks

author: Zero999
author_rank: Super Contributor
timestamp: April 15, 2025, 07:32:43 am
content: Where are the grounds of the +50V and - 50V power supplies? Are they isolated from the +5V supply?

author: Terry Bites
author_rank: Super Contributor
timestamp: April 15, 2025, 08:02:42 am
content: Zero999 Asks if the voltage sources are isolated (ie they do not share a common ground) with good reason.If the ADC inputs are truely differential then you'd just pot down the voltages.For the -50V input pot down and reverse the polarity at the ADC.If there is by accident or design a common ground shared by the two voltage sources, this will not work.Magic smoke may pay you visit.In principle your offset scheme works. The slope of the -50V input is negative, you'd fix that in code.You could set the offset and slope a little more accurately.Use R1 and R2 to pot down the 50V to FSR.Use R3 and R4 to add an offset of 2xFSR.BTW, here's very handy resistor ratio calculator>https://jansson.us/resistors.html

author: imblunt
author_rank: Newbie
timestamp: April 15, 2025, 11:36:42 pm
content: Heythanks both. yes the + and - 50v DC are completely isolated from the rest of the system powering the ADS1115.the idea was to fix the reverse slope in code as you mentioned.

author: Zero999
author_rank: Super Contributor
timestamp: April 16, 2025, 07:57:10 am
content: Quote from: imblunt on April 15, 2025, 11:36:42 pmWhich are the positive and negative connections to J13 & J12? Presumably they both share a 0V/ground node i.e. are connected together in series?
Metal core PCB prototyping? - Page 1
Forum section: electronics / projects

author: ajb
author_rank: Super Contributor
timestamp: May 12, 2015, 12:44:21 am
content: Anyone know of a board house that will do low quantities of aluminum core PCB at a decent price? Don't need anything fancy, just a few single-layer ~40mmx135mm rectangles so I don't have to hand wire another couple dozen RGBW LED star boards. I looked at a number of the low cost places but none of them seem to offer metal core as a standard option, or maybe I just missed it.

author: Tombs Balsam
author_rank: Newbie
timestamp: May 18, 2015, 03:45:05 am
content: Quote from: ajb on May 12, 2015, 12:44:21 amMaybe you can have a try withwww.pcbway.com/e
Metal detector nice website with doc / BOM / PCB .... and a lot of info - Page 1
Forum section: electronics / projects

author: Overspeed
author_rank: Frequent Contributor
timestamp: October 11, 2024, 01:54:46 pm
content: Helloa very interesting website for DIY metal detector with performanceshttps://simplemetaldetector.com/pulse-induction-metal-detectors/pim-2-pi-metal-detector/pim-2-pulse-metal-detector/RegardsOS

author: dusan
author_rank: Regular Contributor
timestamp: October 11, 2024, 04:14:26 pm
content: I did lot of experiments some time ago, I've tested maybe 20 different schematics, most of them were garbage and the only usable results I got (detect coin at 15cm) was with DiodeGoneWild's induction balance detector and with simple direct frequency measurement using arduino (also coin at 15cm). Biggest disappointment (ratio of efforts vs. results) was pulse induction type, it worked but I just couldn't even get it close to required sensitivity, and the only thing that remained from it is this bad boy (UNI-T for scale).I now have one pinpointer in the works, there are few remaining thing to solve (14500 battery that I'm waiting for and few different coil tests). It will also be my first "box-first design" as I'm trying to reduce the amount of jank in my builds.
metal lined IEC connector inlet without filter? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: June 13, 2021, 03:08:31 am
content: For retrofiting old oval connectors on ancient stuff, I often replace them with IEC connectors, but the problem is unless you want to do too much sheet metal work, its not shielded, and the oval ones are kinda screened. is there is manufacturer of normal IEC inlets that happens to have a metal screen on it that happens not to have a filter, i.e fit in equipment thats too small. i know the filter ones are shielded but they are too large.this is usually a shitty job that requires a die grinder on stuff slightly too thick for a nibbler lol, talk about vibration testing, but I can't tolerate a multi cable system, its just too muchnot that it really matters about the shield because these things are usually high voltage, have massive vent holes, etc.. its probobly doing nothing
Metcal MX500 handles, whats wrong? - Page 1
Forum section: electronics / projects

author: chapai
author_rank: Newbie
timestamp: April 30, 2019, 12:54:30 pm
content: I bought MX500P-11 with 2 handles.Looks the same but with slightly different connectors.1st: STSS RM3E, 2nd: MX RM3E1st smaller work fine. 2dn can't screw into the station. just does not fit.is this handle for another model or required a special adapter?

author: Nerull
author_rank: Frequent Contributor
timestamp: April 30, 2019, 04:44:16 pm
content: Are you reversing the barrel off the connector before putting it on?The bottom style works a bit differently than the top one, it doesn't just thread on. The outside barrel clamps the connector in place. First, turn the barrel until the 'fingers' of the connector are exposed, push them over the connector on the power supply, then thread the barrel over the fingers until its clamped in place.

author: chapai
author_rank: Newbie
timestamp: April 30, 2019, 11:38:24 pm
content: thanks.it probably stuck inside the barrel, and coaxial connector rotated with the barrel, freely.I check the resistanceand it's zeroindefinite. so the wire is broken or disconnected.Next journey to repair the handle. It is possible to but the same connector, to replace old one?

author: JXL
author_rank: Regular Contributor
timestamp: May 01, 2019, 12:17:36 am
content: Like @Nerull said: you have to unscrew the outer sleeve until it looks like this

author: chapai
author_rank: Newbie
timestamp: May 01, 2019, 01:00:27 am
content: thanks, I got the point.As barrel stuck, coax connector rotated with it and wire inside detached/ripped off. I mistakenly say zero resistance. actually, it is the opposite no connection.I can reuse this connector, but still, probably need to cut the plastic and resolder.

author: Monkeh
author_rank: Super Contributor
timestamp: May 01, 2019, 08:20:50 pm
content: No connection to what?

author: chapai
author_rank: Newbie
timestamp: May 01, 2019, 09:47:24 pm
content: central pin to the metal barrel.it should be just coil inside.

author: Monkeh
author_rank: Super Contributor
timestamp: May 01, 2019, 11:00:46 pm
content: Only with a tip inserted. I think they're DC coupled..

author: chapai
author_rank: Newbie
timestamp: May 01, 2019, 11:19:42 pm
content: I put the tip in 2nd and no connection between piт and barrel.But with 1st it's ok.
Mete-O-Mate - Tubes provide weather information - Page 1
Forum section: electronics / projects

author: balu
author_rank: Regular Contributor
timestamp: August 28, 2017, 06:38:48 pm
content: Hello,After long time of research and development I find a way to get weather data from the internet with a tube based circuit. It works very well and will update the current weather and the three day forecast every 10 minutes.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: August 28, 2017, 07:07:33 pm
content: I like the 1S2 diode!

author: calexanian
author_rank: Super Contributor
timestamp: August 28, 2017, 08:00:03 pm
content: Wait. Is that reporting the weather, or making it?

author: Rbastler
author_rank: Frequent Contributor
timestamp: August 28, 2017, 08:03:17 pm
content: Is there A E/PY88 and a E/UCH81 on it, along with 1S2/DY86 ?

author: calexanian
author_rank: Super Contributor
timestamp: August 29, 2017, 03:36:58 am
content: Can Mork Call Orson on that? It really is cute.

author: floobydust
author_rank: Super Contributor
timestamp: August 29, 2017, 04:29:33 am
content: Contribute to global warming and power up the filaments

author: duak
author_rank: Super Contributor
timestamp: August 30, 2017, 04:14:28 am
content: Do I see a Nuvistor inside of larger tube? Or could it be an actual interocitor?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: August 30, 2017, 04:42:23 am
content: Quote from: duak on August 30, 2017, 04:14:28 amLooks like it, but it's just the anode.

author: Molenaar
author_rank: Regular Contributor
timestamp: August 30, 2017, 04:16:46 pm
content: At least use red/orange LEDs underneath the tubes, if you don't want to power up the filaments...

author: Vtile
author_rank: Super Contributor
timestamp: August 30, 2017, 06:03:35 pm
content: I wonder if that mete-o-mate could be used to control the weather with addition of the flux capacitor.
Meteo station for Windy - Page 1
Forum section: electronics / projects

author: Ivan Donev
author_rank: Newbie
timestamp: October 12, 2023, 01:40:19 pm
content: Hi Everyone,Just built a meteo station, which successfully sends temperature and pressure to Windy's global meteo map.Its readings can now be seen live on the map and I'm thinking of next attaching a solar panel and installing it somewhere downtown (near some WiFi).It uses ESP32 for main board and a BMP280 sensor with two 4.7kOhm pull-up resistors on SCL and SDA:It's made with Iot cafe, based on the meteo station example on the site.Here's the project:And the project's web relay for sending to windy:The web relay URL is:Code:https://stations.windy.com/pws/update/?temp={{AirSensor.temperature}}&mbar={{AirSensor.pressure}}where theis a personal code, which I got from Windy when I registered the meteo station.Cheers!
Methodology of testing lead acid batteries. - Page 1
Forum section: electronics / projects

author: maximafly
author_rank: Newbie
timestamp: March 06, 2020, 08:32:27 pm
content: Hi Guys, I'm new here, I have searched the forum and general internet already, I am trying to find out how these modern automotive 12v battery testers actually test the battery, for example you input the SAE rating of the battery and after a few seconds it responds with battery voltage, internal resistance, actual capacity and charge level. How does it actually test this as the leads are not thick enough to put the battery under a high load. I am still trying to find out and will post here if I find anything. I would like to replicate something like this with an arduino to get an understanding of what is going on. Any input would be appreciated.
methods reducing |VGS| of a mosfet question - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: October 29, 2024, 08:50:44 pm
content: Hello,As you can see below M1 Vgs is 14V.I dont need 14V to open this transistor , I need only 5V.I have extra Vgs, Is there a way to reduce the Vgs?Thanks.

author: Salitronic
author_rank: Contributor
timestamp: October 30, 2024, 12:49:47 am
content: If the input voltage is fixed and known you can just add a resistor across C10 to form a voltage divider with R4.If the input voltage is variable then you can add a 5V Zener diode across C10 to cap the voltage.You should also add some resistance in series with C10, as it is now C10 will discharge directly into U1 and U2 when their outputs go low, it's quite a large capacitor and the discharge current will damage the comparator output.
Metrix+ DM 620 multimeter - Page 1
Forum section: electronics / projects

author: Everbrave
author_rank: Regular Contributor
timestamp: June 11, 2025, 09:56:55 am
content: This logging multimeter is made in India. The specs. look good; 50000 counts, basic accuracy 0.05 on VDC.Does anyone own this multimeter and can share his experience?Additional info. is much appreciatedThanks
Mezzanine rated for high cycle count? - Page 1
Forum section: electronics / projects

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: January 19, 2018, 07:49:38 am
content: Hi everyone!I'm looking for a 30 pin mezzanine (at least it must be a thin board to board connector with signal integrity good enough for USB 2.0 HS) that has, say 3000 cycles or more.The closest I've seen is Hirose DF37 series which advertises a 3000 cycles rated part. Though, can't find it on the website....Anyone happen to know of something?I'll use it for a compute module which will be inserted and removed many times.Thanks!
MFDC Welding Inverter Control Strategy  - Page 1
Forum section: electronics / projects

author: ow19m
author_rank: Contributor
timestamp: May 05, 2022, 07:00:37 am
content: Hello ,I'm designing an MFDC Inverter and I stumbled upon a thread given below which has helped me alot in finding my mistakes . Does anyone have the Resource or can help me in controlling the system like the one shown in the article , Im basically using a 100KVA 50/60Hz transformer ,my frequency will in between 60 - 400 Hz , not using a high frequency transformer for now . I understand how to control an inverter and how IGBT's are fired /Timing etc ,But I m still confused whether what im supposed to do in order to control Current, either start frequency from 400Hz and then lower the frequency to the desired frequency or apply PWM strategy in order to have Significant Savings in electricity Bill , Your help will have a great impact on my understanding.https://www.eevblog.com/forum/projects/high-frequency-igbt-h-bridge-snubber-network-question!-reusing-medar-spotwelder/