hybridfree/eevblog-posts huggingface dataset:
Chinese Production House - Page 1
Forum section: electronics / projects

author: veryevil
author_rank: Unknown
timestamp: March 02, 2011, 04:10:40 pm
content: Hi, the company I work for is looking to outsource our pcb manufacture to china to save costs as currently we use a UK based production house.We are looking for a full turnkey solution where they source the parts, etch the pcb and populate it. Which is what we have in the UK currently.The quantities we would be ordering would be 50-5000 pieces. Would this be enough? Smaller orders we could still get in the UKWe are a small company and its very had to get into the Chinese market.Who do you use / can recommend?Thanks Steven

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: March 02, 2011, 04:56:01 pm
content: PCBCart has worked well for me. Fast service, promised as delivered. They are a full service fab and will make from 1 to many boards.Here's an articleI did on places I've used or that I've heard reputable things about. And actually, whether small quantity or large, there are some great Chines solutions. For smaller quantities, if delivery time isn't too critical, you'll be amazed at the prices you can find.PCBCart uses express delivery like DHL. For an order of 150 7 sq inch boards, the delivery charge was $50...but the total cost was only $250 for 150 boards.Jon

author: Simon
author_rank: Unknown
timestamp: March 02, 2011, 05:41:11 pm
content: Quote from: veryevil on March 02, 2011, 04:10:40 pmpresumably you've already worked out what people are getting for their redundancies

author: veryevil
author_rank: Unknown
timestamp: March 02, 2011, 09:15:48 pm
content: thanks for that. I didn't realise PCB cart did full service production.might have to get a quote.

author: Psi
author_rank: Super Contributor
timestamp: March 03, 2011, 08:04:32 am
content: Another company you could look at ishttp://www.ourpcb.com/I had them make some boards a year or so back and they turned out great.They seem friendly and spoke good english in the emails i had with them.They even sent me a card for new years.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 31, 2011, 03:27:05 am
content: Custom PCB Fabrication from China-www.circuit-mart.com?. any idea?

author: v8dave
author_rank: Regular Contributor
timestamp: June 04, 2011, 02:18:22 am
content: I recently got prices for some boards from this company. (I have not yet used their service)http://www.myropcb.comThey are based in Canada but the out sourcing is from China.The prices I was quoted where very good and I am likely to use this company shortly as they were lower than the previous China company I used (who suffered from QA issues. Good PCB's but poor fabrication)Dave...
chinese resistor color code - Page 1
Forum section: electronics / projects

author: radiomog
author_rank: Regular Contributor
timestamp: January 29, 2015, 06:13:12 am
content: did these guys invent their own color code for resistors?I got an assortment of 1/4w metal film resistors.the ones I got were on tape in qty of 20 each, stamped with their value on the tape.The stamped value was fairly accurate when checked against my Fluke DMM.the Resistor Color bands on the other hand were not marked properly on the majority that I had checked.I contacted the seller, see what the deal is. This can cause some major headaches down the road.I questioned my own learning, had to go verify that what I learned a long time ago, still applies, and it does. (BBROYGBVGW)I have a decent supply of 1/4w carbon film, just wanted to expand my stock a bit with a variety.you get what you pay for and all that, but how hard do you have to try to mess up a long standing standard? Maybe they're factory "seconds"? IDK. waiting for an answer.

author: Richard Crowley
author_rank: Super Contributor
timestamp: January 29, 2015, 06:27:30 am
content: What does "not marked properly" mean?I got an assortment of resistors that are very difficult to read.Its not that they used the WRONG colors, but the colors are not very bright, and not really "pure" colors.If you know the value, you can look at the colors and say: "Yeah, I guess that could be brown red orange".

author: radiomog
author_rank: Regular Contributor
timestamp: January 29, 2015, 07:55:59 am
content: wrong colors used, typically the 3rd band.might upload a photo later tonigh.

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 29, 2015, 12:04:16 pm
content: Maybe you did read them in reverse order and did read the tolerance band as the first digit and vv?
Chinese Soft Start unit - Problem - Page 1
Forum section: electronics / projects

author: fqahmad66
author_rank: Regular Contributor
timestamp: August 06, 2017, 03:38:17 pm
content: Hi guys,A need some help understanding the Strange Chinese Soft Start. Reversed Engineered the schematic. The soft start behaves rather strangely.If a remove the dotted link in schematic, it requires two pushes of tact switch to energize. Off is ok with one push.If I install the link, it energizes with one push of switch, but wont turn off with the switch.I have attached a 400VA Transformer PS to it.Best RegardsFarooq

author: fqahmad66
author_rank: Regular Contributor
timestamp: August 07, 2017, 08:43:42 am
content: Well got it reasonable working. Have to connect both LEDs. One for Standby and on for Power. Also the link should not be there. Attached are corrected schematic and images of top and bottom with visible tracks for somebody to troubleshoot or even to build ones own.Best RegardsFarooq
Chinese Strain gage part number - Page 1
Forum section: electronics / projects

author: sylvanoMTL
author_rank: Contributor
timestamp: April 23, 2025, 08:29:43 am
content: I am looking at some strain gage, in particular the BF1k-3EB.I want a full bridge strain gage for Aluminum, with 1k resistanc on each gage.Aliexpress has multitude of products, but I cannot find any reference to part numbering. Does anyone has a source for it?What kind of quality to expect from these untraceable product?I am at a early stage developping my application so I am quite loose with resolution/accuracy. But I am keen to find alternatives not too pricey

author: zapta
author_rank: Super Contributor
timestamp: April 26, 2025, 07:42:58 pm
content: If this is for production and you want a Chinese source than it's more stable and informative than what you find on Aliexpress , you may want to search at Alibaba. E.g.https://www.alibaba.com/product-detail/BF120-High-Precision-Full-Bridge-Strain_1601425251960.html?spm=a2700.galleryofferlist.normal_offer.d_title.651413a0uMcxjF
Chinese stuff - how is work ? - Page 1
Forum section: electronics / projects

author: yabba235
author_rank: Contributor
timestamp: December 06, 2023, 06:44:04 pm
content: Hi!Put in my hand mini audio amplifier from China - it use HV amplifier chip from apex manufactury. It use very strange aplication of flyback conventer base on TL494 PWM driver. I cannot compare this system to any example of using this system found on the Internet - can someone help me and explain to me how it works?I just wanted to make a similar power supply but I can't find any diagram that would correspond to this system.I am attaching a photo of the board - the output is an FTDP 20n50 n-mosfet controlled in parallel from outputs e1 and e2.I suspect that this is a copy of the power supply circuit from the Stax SRM-D10 portable amplifier. I don't know how the Chinese copied this system (there are no diagrams for me), but they managed to do it.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 06, 2023, 08:14:27 pm
content: pls straighten the mosfet we don't see under itan serious smps application has one more transformer to do the tl494 coupling, in case of the main section who could blow, the tl494 get isolationthis circuit seems simple you could do a schematic yourselfand for sure you should have a feedback line who should from the xformer secondaries and goes back to the tl494, normally thru an optocoupler etc ...but this circuit seems pretty cheap and cut on quality / functionality, and show us a zoomed out picture of this section, we may miss some parts

author: yabba235
author_rank: Contributor
timestamp: December 06, 2023, 08:24:01 pm
content: A few photos:

author: yabba235
author_rank: Contributor
timestamp: December 06, 2023, 08:25:43 pm
content: A fews photos more:

author: yabba235
author_rank: Contributor
timestamp: December 06, 2023, 08:30:32 pm
content: This circuit has no optocoupler, only voltage divider from output voltage. I can't recognize configuration of error aplifiers from 494 chip - without cleer look track and pads seems is impossible recreate schematic.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 06, 2023, 09:07:51 pm
content: Quote from: yabba235 on December 06, 2023, 08:30:32 pmNo BGA array parts so you can figure connectivity with ohmeter between pins. Not as easy as viewing bare board, but straightforward.

author: Terry Bites
author_rank: Super Contributor
timestamp: December 07, 2023, 04:18:23 pm
content: I've seen a few TL494 based amplifier circuits. The PWM controller can be used open loop to provide the class D action. The internal error opamps might be used as audio gain stages (arrgh!).You might not have a conventional TL494 application at all. Its not being used as a power supply circuit.eghttps://www.elcircuit.com/2018/03/diy-500w-class-d-tl494-switching.html

author: yabba235
author_rank: Contributor
timestamp: December 08, 2023, 03:01:34 pm
content: Quote from: Terry Bites on December 07, 2023, 04:18:23 pmNo, in this case TL494 work in "normal" mode, no D class audio aplifier.
Chinese TDA7377 2.1 Amplifier Kit - Page 1
Forum section: electronics / projects

author: Harvey17
author_rank: Contributor
timestamp: December 05, 2019, 09:54:47 pm
content: I've just put together one of these little Chinese kit TDA7377 amplifiers -https://www.aliexpress.com/item/32804621834.htmlAll working quite well considering, however there is quite a loud THUMP on the subwoofer at switch on. The datasheet for the TDA7377 states the chip has silent turn on/off, so I'm guessing the cause is the offset of the NE5532 used as a pre-amp for the subwoofer section.So, simple question is - any suggestions as to how to get rid of this? Are there any suitable opamps to replace the NE5532 with 0-offset? Am I missing some simple way of fixing this problem?

author: magic
author_rank: Super Contributor
timestamp: December 05, 2019, 11:17:49 pm
content: Maybe there is some shutdown pin on the chip amp which could be used to keep it disabled for a moment after power on?Another thing is that this TDA7377 may not actually be a TDA7377 and the NE5532, by the looks of it, most likely is not an NE5532

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 06, 2019, 03:06:21 pm
content: Looking at the TDA7377 datasheet (assuming the one on this board is genuine), there's a "stand-by" pin (pin 7). To delay the power-on of the amp, you'd need to connect it to the power supply through an RC network. Check what this pin is connected to on the board.
Chinese TL431 super capacitor balancer - Page 1
Forum section: electronics / projects

author: wictor
author_rank: Regular Contributor
timestamp: February 24, 2019, 03:30:53 pm
content: Hi,I wanted to share my experience of Chinese TL431 super capacitor balance and protection board design and it's flaws. There are many of them available from various sellers.This is photo of the board:The designer wanted probably do something like this:And circuit would work so, that it limits the capacitor voltage to 2.65 as seen in this plot:However the board had some design flaws and it actually was more like following circuit:Which was drawing current as soon as voltage was above 0.7V.So, there was two problems. TL431 was connected incorrectly, the layout would work with TL432, since it has ref and cathode swapped. And another problem was that SOT23 with marking Y2 was actually 12V zener(I verified this by desoldering it and measuring the breakdown voltage) and not SS8550, which would work and has also Y2 marking...Cheers,Wictor

author: exe
author_rank: Unknown
timestamp: February 24, 2019, 04:15:17 pm
content: Wow, that's nuts! So, basically, they used random sot-23 components and it didn't work at all...

author: magic
author_rank: Super Contributor
timestamp: February 24, 2019, 04:37:42 pm
content: Haha, that's what happens when you buy your parts on those AliExpress auctions where SMD components are only described by their markingsSpeaking of TL431 fails, I bought an adjustable voltage wall wart once whose lowest setting is 3.3V.The problem is, regulation is done by a TL431 sinking current through an optocoupler LED. The LED has a forward voltage of 1.2V and the TL431 barely sinks anything until its cathode reaches 2.5V.This PSU will never, ever regulate less than 3.7V

author: wictor
author_rank: Regular Contributor
timestamp: February 24, 2019, 04:55:55 pm
content: There are many versions of similar design sold from China. I think they have not tested the this layout at all, since TL431 cannot work with swapped ref and cathode in this kind of purpose...Heh, but anyway this design is not going to keep caps charged for too long
chip antenna feed with reference plane and without reference plane - Page 1
Forum section: electronics / projects

author: electronx
author_rank: Regular Contributor
timestamp: September 15, 2024, 05:38:13 pm
content: I am trying to design a pcb using a chip antenna. I see that in some reference layout topologies a reference plane passes under the feed trace and in some there is no reference plane. What is the difference between these?Do I understand correctly?

author: selcuk
author_rank: Frequent Contributor
timestamp: September 15, 2024, 08:59:25 pm
content: That transmission line is a coplanar waveguide. Check the link below:https://en.wikipedia.org/wiki/Coplanar_waveguideYou can do it either with or without a ground plane. But it is a better wave guide with a ground plane. Using a ground plane is better for reducing cross talk issues. I think the manufacturers made the calculations about the track width, spacing and dielectric heights with respect to that ground plane so they suggest using it. If you don't want to use a plane, you need to recalculate the track parameters. Additionally, if you want to use a different layer stack (different thickness and Dk of dielectric etc.) you need to recalculate as well.But do as suggested for the ground plane right under and around the chip antenna.

author: Salitronic
author_rank: Contributor
timestamp: September 16, 2024, 05:02:09 am
content: They a different variants of the coplanar waveguide. Generally it is more common to use a coplanar waveguide with ground plane (GCPW), particularly if you have a long feedline, bends or enclosure wall very close to the board. The ground plane in a GCPW serves not only for impedance matching but also for the return current, for a long CPW feedline (without ground) this return current needs to be handled correctly.Note that the 2 chip antennae that you listed are quite different. The first one is an unusual chip antenna that is designed to be mounted directly over a ground plane. In this case the obvious choice is a GCPW feedline. This antenna is meant for very compact designs in which not needing metal clearance under the antenna is a significant convenience. There is a catch however as the efficiency of that antenna is quite low, only 38% on a typical 1.5mm board.The other antenna is a more common type of chip antenna requiring metal clearance underneath it and has better efficiency. In this case you can choose either CPW or GCPW. GCPW is generally preferred.Note that the dimensions and spacing calculations for the feedline will be different for CPW and GCPW.
Chip antenna layout - Page 1
Forum section: electronics / projects

author: electroro
author_rank: Newbie
timestamp: August 03, 2021, 05:22:25 am
content: Hey folks,I am a beginner in RF and designing my first board with an antenna on it.I have referred the datasheet as much as i could.It is a 4-layer board with signal(red)-GND(yellow)-VDD(pink)-signal(green) stackup. The transmission line is 0.34mm (50 ohm impedance)Would love to get your opinions on the design.I am using a small molex 2.4GHz ceramic chip antenna due to space and availability constraint.The IC is a NRF52840.datasheetshttps://www.molex.com/pdm_docs/as/2030060001-AS.pdfhttps://www.molex.com/webdocs/datasheets/pdf/en-us/2030060001_ANTENNAS.pdfThank you

author: obuone
author_rank: Contributor
timestamp: August 04, 2021, 01:00:06 am
content: Hey electroro, if you have followed the data sheet example layout and matching network everything should be ok. The only thing is it seems the your ground plane doesn't connect to the ground pads of the chip antenna. Since you have added "keep out" region where the ground plane cut out should be, it stops the ground plane to properly attach to the GND pads of the antenna.
Chip / Circuit Question - Page 1
Forum section: electronics / projects

author: docmur
author_rank: Regular Contributor
timestamp: June 29, 2016, 10:30:43 pm
content: Hey GuysWhat is the best way to track head movement in three dimensions? I know IC's exist which calculate 3, 6 and 9 degrees of freedom but can this be done with simpler accelerometers?ThanksDocmur

author: uncle_bob
author_rank: Unknown
timestamp: June 30, 2016, 12:43:15 am
content: Quote from: docmur on June 29, 2016, 10:30:43 pmHiYou can buy three axis accelerometers. You can also buy three axis gyros. The combination of both is a fairly typical way to get the job done.Bob

author: ebclr
author_rank: Super Contributor
timestamp: June 30, 2016, 12:55:51 am
content: To help on prototypehttp://pt.aliexpress.com/item/Free-shipping-CJMCU-117-MPU9250-MS5611-High-precision-9-shaft-10-dof-module-SPI-IIC-communication/32569603963.html?spm=2114.02010208.3.10.RJaZS3&ws_ab_test=searchweb201556_8,searchweb201602_4_10037_10017_405_404_507_10033_10032_10040,searchweb201603_3&btsid=89e6f123-b927-410f-b9c9-0bc34e7167e4

author: docmur
author_rank: Regular Contributor
timestamp: June 30, 2016, 01:01:37 am
content: Okay cool, that's very much like the chip I'm trying to use then. I have tight size requirements, max 28mm x 14mm. I'm putting a combination accelerometer and gyros on my small board with a PIC18F and some other chips for my purpose. Just wanted to make sure I was heading down the right track.
Chip Enable funtion of buck converter - Page 1
Forum section: electronics / projects

author: Nikos A.
author_rank: Regular Contributor
timestamp: December 29, 2021, 11:58:11 pm
content: Hi guys,I will use the XC9265A331MR-G buck converter in my design. It has a pin namely CE "Chip Enable". The datasheet says, when CE is high the IC is in operation mode while when CE is low the IC is in standby modeThe standby current is 100nA while the quiescent current 0.8 - 2.1uAI will use the converter as the main buck converter to supply the MCU and the peripherals. I have to connect CE with Vin right? In my application, I cannot take advantage of the standby mode, right?So in my case the wiring should be like this:https://eu.mouser.com/ProductDetail/Torex-Semiconductor/XC9265A331MR-G?qs=AsjdqWjXhJ9U1u7bKcUHSA%3D%3D

author: thm_w
author_rank: Super Contributor
timestamp: December 30, 2021, 01:42:19 am
content: Yes.CE pin rated up to 6V so fine to connect straight to Vbatt.One use is if you are say powering another peripheral with this buck supply, and you want to disable it to save power, which you can't do here.

author: Nikos A.
author_rank: Regular Contributor
timestamp: December 30, 2021, 08:46:24 pm
content: Thanks for verifying!! Happy new year!!
Chip ID - Page 1
Forum section: electronics / projects

author: Miti
author_rank: Super Contributor
timestamp: December 28, 2022, 10:09:00 pm
content: Anybody knows what this is?Thanks,Miti

author: inse
author_rank: Super Contributor
timestamp: December 29, 2022, 06:38:39 am
content: Looks like a hot chip from Analog Devices :-)

author: robson2017
author_rank: Contributor
timestamp: December 29, 2022, 09:49:23 am
content: Looks like AD8251ARMZ

author: Miti
author_rank: Super Contributor
timestamp: December 29, 2022, 02:14:01 pm
content: Quote from: robson2017 on December 29, 2022, 09:49:23 amThanks robson2017, that’s it. How do you guys find them?Can you find this?
Chip ID in wireless switch transmitter? - Page 1
Forum section: electronics / projects

author: calzap
author_rank: Frequent Contributor
timestamp: December 09, 2015, 10:03:33 pm
content: Was replacing 12 V battery in transmitter unit of wireless switch pair and was curious about the main chip. Pics are below. Tin can is a 315 MHz SAW resonator, and the TO92 is an A733. SW1 causes "on" signal to transmit; SW2 cause "off" transmission. Can't find a data sheet for the 18-pin dip chip (AUT980202-B), but Google does find some sellers in China. Can anyone provide info?Mike in California

author: amyk
author_rank: Super Contributor
timestamp: December 10, 2015, 03:29:51 am
content: Pinout is similar to HT12E and PT2262, although power supply pins look reversed(?)

author: calzap
author_rank: Frequent Contributor
timestamp: December 10, 2015, 10:12:54 pm
content: Quote from: amyk on December 10, 2015, 03:29:51 amI think you're right; it's a similar chip. The PCB trace connecting the ends of the antenna has a moth-eaten appearance. Is this some sort of tuning or a manufacturing fault?Mike in California

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 11, 2015, 09:04:01 am
content: Quote from: calzap on December 10, 2015, 10:12:54 pmLooks like paint to me.

author: calzap
author_rank: Frequent Contributor
timestamp: December 12, 2015, 05:09:56 am
content: Quote from: PA0PBZ on December 11, 2015, 09:04:01 amWell, I couldn't tell from the pic, so I looked at the actual PCB again. The "moth holes" are actually residual solder flux which was reflecting green color from the surroundings. The trace underneath is intact. The antenna wire on topside, the trace and C4 form a loop. The loop is connected to the rest of the circuit via Q2 and L1.Mike in California
Chip identification - Page 1
Forum section: electronics / projects

author: drhex
author_rank: Regular Contributor
timestamp: March 23, 2021, 09:37:48 pm
content: Hi,have cracked open a non-working netatmo gateway which is losing WiFi after being switched on for a few days. One thing I noticed is a ca 5x5 mm chip marked 820B which seems to have some substrate on top - can't find anything googling it, excuse the lousy photographs. Does anyone have an idea what it might be?
Chip LED with wrong polarity marking? :o - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: October 02, 2021, 08:37:13 pm
content: Hi,This is a first in 25 years...I just had a batch of these LEDs from Digikey:https://www.mouser.co.uk/datasheet/2/239/Lite-On%20PLCC2%20T680%20series%20Catalog%202010-1175321.pdfand they have the cathode marking (little triangle) the wrong way around. If I connect ground to it it does not light up but if I reverse the polarity it does... See attached photos. BTW yes the leads colour/polarity is correctOut of curiosity, has anybody ever come across anything like that?Thank you

author: wraper
author_rank: Unknown
timestamp: October 02, 2021, 08:43:49 pm
content: You purchased them from digikey but link goes to a datasheet from Mouser. Are you 100% sure that datasheet is for the exact part number? Give a link to actual part you purchased.

author: ricko_uk
author_rank: Super Contributor
timestamp: October 02, 2021, 09:04:57 pm
content: Yes that is the part specified in the BOM. I just emailed the assembler to check if they used some alternative part without my authorisation. To be more specific I specified them from Digikey but got them through the assembler (the ones in the pictures are the remaining stock of the order).

author: bson
author_rank: Unknown
timestamp: October 03, 2021, 02:21:04 am
content: What's wrong with the datasheet? It shows the triangle identifies the cathode. Assuming red lead is the supply, that looks correct to me.Edit: oh, you flipped it between the pictures? That does look backwards.

author: wraper
author_rank: Unknown
timestamp: October 03, 2021, 05:55:04 am
content: Quote from: ricko_uk on October 02, 2021, 09:04:57 pmSo you don't even know if they are actually from Digikey. Assembler probably used some cheaper alternative/counterfeit and hoped you wouldn't notice. Also I don't think it should be black anywhere as it is on top, it should be purely white. Cannot find an actual picture of the exact part number, but here is an actual picture of a similar liteon LED.https://lcsc.com/product-detail/Light-Emitting-Diodes-LED_Lite-On-LTST-T680TGWT_C575517.htmlNot to say this LED is out of stock at Digikey. This thread should be called "did the assembler screw me over?"

author: ricko_uk
author_rank: Super Contributor
timestamp: October 03, 2021, 02:16:37 pm
content: Yes they replied and used another part.
Chip manufacturer from logo? - Page 1
Forum section: electronics / projects

author: robstar
author_rank: Newbie
timestamp: May 13, 2013, 04:50:56 am
content: Anyone know who this is?It's labeled "U1" and from its placement, i'm guessing it's a voltage regulator.Thanks!--Rob*

author: marshallh
author_rank: Unknown
timestamp: May 13, 2013, 04:59:50 am
content: Don't recognize, couldnt tell from first glance... Probably an asian fab that is cheap.What is the background on the rest of the device?

author: robstar
author_rank: Newbie
timestamp: May 13, 2013, 05:03:18 am
content: Quote from: marshallh on May 13, 2013, 04:59:50 amCheap is totally the direction to be thinking. The device is a motion-sensing lightbulb fixture that i'm gutting for the PIR sensor. I can't find a datasheet for that either, and was hoping to infer its supply voltage from this chip.

author: marshallh
author_rank: Unknown
timestamp: May 13, 2013, 05:08:11 am
content: Well, it could be a fixed linear reg or an adjustable one. Adjustables generally have a coupel resistors sitting next to it.Look up any generic LDO from National, Linear, NXp, etc in SOT-89 package.Best to check while running with a meter.Pinning could be: GND, Vin, Vout but could just as well be several other combos (quite annoying)

author: robstar
author_rank: Newbie
timestamp: May 13, 2013, 06:36:26 am
content: Quote from: marshallh on May 13, 2013, 05:08:11 amYeah, though this is designed to run off the mains using a light bulb socket, so "while running" will mean a more elaborate operating theater than usual.

author: peter.mitchell
author_rank: Super Contributor
timestamp: May 13, 2013, 07:15:27 am
content: can we see the whole board, so we can rule stuff out ect? see where it sites "in situ"

author: robstar
author_rank: Newbie
timestamp: May 13, 2013, 07:51:00 am
content: Sure! Here's the whole thing, just cracked open (didn't have the right screwdriver... oh wellHere's the top of the board with the PIR and leads that would go to the load (a bulb):Here's the bottom of the board with various ICs (the original mystery one is U1 on the left) and the leads that connect to the mains:

author: robstar
author_rank: Newbie
timestamp: May 13, 2013, 07:56:59 am
content: All the example circuits on the web for the BISS0001 show it and the PIRs it reads as being 5VDC devices, e.g.:http://www.e-voron.dp.ua/catalog/016873has:

author: amyk
author_rank: Super Contributor
timestamp: May 13, 2013, 10:50:10 am
content: http://md-ic.com.cn/datasheet/MD53XX_C.pdfMD5336 3.6V 500mA LDOCompany: Shanghai Mingda Microtronics Co., Ltd.

author: robstar
author_rank: Newbie
timestamp: May 13, 2013, 03:51:33 pm
content: Thanks, amyk! Googling for "biss0001 3.6v" (or "biss0001 3.3v") turns up plenty of non-5v "BISS0001" chips. Anyone know the mfr of this one? Looks like a white circle with the top half of an "S" in black on it. (Or maybe that's a final lowercase sigma?http://en.wikipedia.org/wiki/SigmaOr a stigma?http://en.wikipedia.org/wiki/Stigma_%28letter%29)
Chips for A2DP - Page 1
Forum section: electronics / projects

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 14, 2011, 05:22:55 pm
content: Can anyone give me pointers on locating chips for messing around with A2DP bluetooth? It seems like one of those not possible under 10k units type of things. I might have to hack an existing consumer device.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 16, 2011, 04:14:16 am
content: If the microcontroller (or other host) you're interfacing to has USB, just use a cheap Bluetooth adapter with a good open source driver. Else, UART interfaced modules are also very common.

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 16, 2011, 01:22:36 pm
content: Quote from: NiHaoMike on June 16, 2011, 04:14:16 amI'll probably just hack a consumer device. I keep trying to find even a datasheet on many of these chipsets and failing. Broadcom has a two page worthless info sheet on some of its chips, but nothing that would allow me to take one from a consumer device and use it, without a bunch of reverse engineering.

author: DaveW
author_rank: Frequent Contributor
timestamp: June 16, 2011, 09:54:16 pm
content: Ezurio has some nice development kits, some of which support A2DP. It also might be worth looking at the ubertooth projecthttp://ubertooth.sourceforge.net/which should be a fairly flexible system for generating bluetooth packets-may be able to add on A2DP support easily

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 17, 2011, 01:33:26 pm
content: Quote from: sacherjj on June 16, 2011, 01:22:36 pmIf there's already an open source driver for it, everything you need to know about using it is easily available. UART interfaced modules, in particular, are supposed to be standard.

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 17, 2011, 01:48:03 pm
content: Thanks all, that helps.

author: Psi
author_rank: Super Contributor
timestamp: June 17, 2011, 01:52:18 pm
content: i dunno if this is suitable but sparkfun have some bluetooth stuffhttp://www.sparkfun.com/products/8952

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 17, 2011, 02:21:45 pm
content: Quote from: Psi on June 17, 2011, 01:52:18 pmThat seems to do a bunch, but is about a magnitude higher priced than I hoped.
Chips ID - Page 1
Forum section: electronics / projects

author: Miti
author_rank: Super Contributor
timestamp: June 05, 2021, 07:45:09 pm
content: I have few 9V rechargeable batteries from Banggod and one stopped charging. I left it charging all night and the LED was still on in the morning. I opened it and the wire from the battery pack to the board was flapping in the wind. Not soldered at all, it must have just touched the pad because I charged it many times.Anyway, I was trying to identify the chips on the board without much success.There's a Li-Po charger, a step up regulator and something else. Can anybody identify these chips?Cheers,Miti

author: amyk
author_rank: Super Contributor
timestamp: June 05, 2021, 09:01:02 pm
content: 5350A -XB5350A2YL6 -LN2054Y42AMRCan't find U07QA - probably a boost converter.

author: Miti
author_rank: Super Contributor
timestamp: June 05, 2021, 10:16:18 pm
content: Quote from: amyk on June 05, 2021, 09:01:02 pmThanks amyk!

author: gamalot
author_rank: Super Contributor
timestamp: June 05, 2021, 11:25:37 pm
content: Maybe it is UB7QAhttps://datasheet.lcsc.com/lcsc/1912111437_Silergy-Corp-SY7152AABC_C408954.pdfThe R2/R3 voltage divider network is connected to the negative feedback Pin 3, so the output voltage is set to approximately 9.8V. Pin 1 is connected to the inductor and diode, and pin 4 is connected to the enable input, which are consistent with the pinout of SY7152.

author: Miti
author_rank: Super Contributor
timestamp: June 06, 2021, 12:23:52 am
content: Quote from: gamalot on June 05, 2021, 11:25:37 pmI think that's it. The marking, the pinout, the feedback voltage, everything matches. Thanks gamalot!
Choosing a bus for controlling 20 pic12 50mm apart - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: February 11, 2015, 10:48:54 am
content: Hi,some time ago i made a small board with a pic12 controlling one rgb led.Now i have some boards left (more or less 20 ) and i would like to connect the boards in one bus and be able to control them.I have two i/o left on the pic12.The distance between two board should be no less than 50mm ( 1m in total).What kind of bus should i use?I was thinking i2c but i don't know if the lenght of the cable can be a problem.Thanks for the help

author: jb79
author_rank: Contributor
timestamp: February 11, 2015, 12:45:25 pm
content: Hi!1m should be possible.It's important that the capacity of the bus doesn't go over a certain level. Otherwise the rise time (0=>1) would be to high for the system.There are several ways to solve such problems:lower bus speed i possiblebus bridge/repeater to split the bus into two or more shorter segments...The best idea would be to try it with 2 or 3 of your boards connected to a 1m cable.best regardsJuergen

author: fcb
author_rank: Super Contributor
timestamp: February 11, 2015, 04:43:57 pm
content: Quite possible to do without any buffering/extra components - but will depend on speed (bus capacitance and ground noise).

author: Unknown
author_rank: Unknown
timestamp: February 13, 2015, 12:15:52 pm
content: I will try and let you know. Any advice on the type of cable ?Sorry for the late response.

author: Christopher
author_rank: Frequent Contributor
timestamp: February 13, 2015, 02:36:25 pm
content: How aboout an i2c serial interface?Each pic is a master as well as a slave, only responds to data with its own address then shoves all the rest out to the next pic?This way you may not need to have a buffer on each chip

author: Unknown
author_rank: Unknown
timestamp: February 13, 2015, 03:27:19 pm
content: Quote from: Christopher on February 13, 2015, 02:36:25 pmI can't do serial i2c because i have only two i/o left.I took a quick glance at this appnote:http://www.maximintegrated.com/en/app-notes/index.mvp/id/148and it seems that i can use the 1-wire protocol.Later i will read it more carefully and maybe do some tests.

author: Christopher
author_rank: Frequent Contributor
timestamp: February 13, 2015, 03:29:17 pm
content: I have used the p82b96 i2c bus buffer successfully over a few m,
Choosing a Connector - Page 1
Forum section: electronics / projects

author: krenzo
author_rank: Regular Contributor
timestamp: April 11, 2012, 06:35:13 am
content: Hi, I'm working on a project that is transferring differential signal pairs over wires. I'm using shielded ethernet cables right now, but I want to move over to something with a smaller connector. I was thinking of using HDMI since the cables are plentiful and cheap. Now, my concern is what are the legal complications of using HDMI connectors? Apparently, you're supposed to pay licensing fees if you make an HDMI device. Since I'm just using the connector and sending my own signal over the wire, does anyone care if I start selling a device that uses one of these cables but not the HDMI signal standard?

author: joelby
author_rank: Frequent Contributor
timestamp: April 11, 2012, 06:46:44 am
content: Pretty sure the licensing restriction only applies to HDMI signals, but if you're making a commercial product you might want to check to remove any doubt.If you need additional differential pairs, you could also consider a mini-SAS cable (SFF-8087). They have 36 pins and weren't fabulously expensive when I checked.

author: amyk
author_rank: Super Contributor
timestamp: April 11, 2012, 07:32:13 am
content: You should at least make it so that no damage occurs if someone plugs your device into a real HDMI device --- i.e. use the same voltage signals and pin assignments.

author: Psi
author_rank: Super Contributor
timestamp: April 11, 2012, 10:51:26 am
content: Pretty sure all the HDMI licensing issues only come into play when you imply your device is HDMI complaint or you use the HDMI logo

author: T4P
author_rank: Super Contributor
timestamp: April 11, 2012, 11:12:38 am
content: You have to pay royalty fees if you want to advertise your product as HDMI-compatible or the like .And using the HDMI logo , well it's best to not say so much about HDMI then you might be able to get away scot free .
Choosing a microcontroller - Page 1
Forum section: electronics / projects

author: JuanGg
author_rank: Regular Contributor
timestamp: November 07, 2019, 08:34:56 pm
content: I am looking for a microcontroller for an automotive application,Main (given) requirements are:-32 bit-Dual CAN-USB-Dual UART-Several PWM-12 bit ADCI have been searching on Mouser and Digikey and found some that satisfy the criteria, but on top of that, ease of use and good documentation are a must as I have limited experience if none on the subject. Even some sort of evaluation board would be handy. Any pointers on where (or how) to look?Juan

author: Nikos A.
author_rank: Regular Contributor
timestamp: November 07, 2019, 08:53:23 pm
content: How about the ESP32-WROOM-32?https://eu.mouser.com/ProductDetail/Espressif-Systems/ESP32-WROOM-32?qs=chTDxNqvsyltcwz%2FUUJDtQ%3D%3D

author: coppice
author_rank: Super Contributor
timestamp: November 07, 2019, 08:56:28 pm
content: Quote from: JuanGg on November 07, 2019, 08:34:56 pmDo you need an automotive qualified MCU? If you do, that will narrow your choice a lot.

author: nctnico
author_rank: Super Contributor
timestamp: November 08, 2019, 12:26:44 am
content: NXP has some choices in their line-up.

author: viperidae
author_rank: Frequent Contributor
timestamp: November 08, 2019, 04:00:34 am
content: You could try looking at some of the stm32f4 series. Some of those have dual can controllers and cheap nucleo dev boards.

author: bson
author_rank: Unknown
timestamp: November 08, 2019, 06:07:17 pm
content: Better to use the product selectors of the various vendors - NXP, TI, ST, etc.E.g.,https://www.st.com/en/microcontrollers-microprocessors/stm32-mainstream-mcus.html#products

author: JuanGg
author_rank: Regular Contributor
timestamp: November 08, 2019, 06:49:03 pm
content: Thanks everyone, I'll see what I can do.Juan

author: Scrts
author_rank: Frequent Contributor
timestamp: November 08, 2019, 07:06:04 pm
content: If this will be for automotive OEM, then they all have a list of pre-approved microcontrollers. Another point is that if you will need to run AUTOSAR.In general, your main options are mostly from Infineon, ST, Renesas and NXP.
Choosing a PI, to stream 4 usb webcams. - Page 1
Forum section: electronics / projects

author: Supper_slash
author_rank: Newbie
timestamp: March 12, 2018, 04:27:56 pm
content: I stream on twitch and youtube. The webcams I use are{LE 20.0 M Pixel USB 6 LED Webcam Mic PC Laptop Camera}.I connect webcam A&B into a USB hub, into my USB port 1.And then webcams C&D into a USB hub, into USB port 2.All on my PC.Doing this I am able to stream ALL 4 cams at the same. And then choose what cameras I need to be using, or all 4.I wish to find a "PI" that can take over outputting 4 streaming cameras onto a "closed server {192.168.1.222}" type setting so I can use them as needed.I no pi's have 2-4 USB ports but has anyone tried to have it output 4 cams at the same time?I may need to use 2 pi's to do this task, either way, I am looking for suggestions.ALL I am looking for is 4 streamed USB webcams I can use as a server, then pull it into OBS software to stream, and switch what cams I want, etc.Eventually, I will have some camera automation going on later, all being controlled by the PI.

author: tyrel
author_rank: Contributor
timestamp: March 12, 2018, 08:26:45 pm
content: If your usb cameras support jpg compression, you could use the MJPG-streamer software :https://sourceforge.net/projects/mjpg-streamerIt converts directly the jpg frames from the camera to a mjpeg stream over http, with no reencoding.Since there is no video encoding, it doesn't need much cpu power at all, so you probably wo'nt be limited by the cpu.Depending on the camera resolution and framerate, you could be limited by the ethernet and usb bandwidth, since they share the same controler on a raspberry.

author: Supper_slash
author_rank: Newbie
timestamp: March 12, 2018, 08:50:22 pm
content: TY I will look into that.
Choosing a power entry connector - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: August 03, 2016, 06:34:12 am
content: I'm trying to choose a power connector. Any recommendations?- 24VDC, 2A max.- 2 pins (V+ and Gnd)- Cheap is good.- PCB mounted, right-angle, will poke through a plastic housing but does not have to be mechanically held onto the plastic.- Must have some sort of clip or lock, cannot be pulled straight out.- Typical "barrel" power connectors are therefore no good.

author: prasimix
author_rank: Unknown
timestamp: August 03, 2016, 07:12:27 am
content: Perhaps MolexMini-Fit Jr.? Latched, 4.2mm raster up to 13 A, 600 V.As cheaper then genuine crimping tool aPAD-12could be used.

author: DutchGert
author_rank: Frequent Contributor
timestamp: August 03, 2016, 07:45:29 am
content: Or the Wurth clone (MPC3), a lot cheaper. I use them all the time.http://katalog.we-online.de/en/em/MPC3_3_00_FEMALE_SINGLE_ROW_RECEPTACLE_HOUSING_6620XX013322?sid=8687082314

author: ajb
author_rank: Super Contributor
timestamp: August 03, 2016, 11:34:11 am
content: Quote from: DutchGert on August 03, 2016, 07:45:29 amThose look to be clones of the Micro-fit (3mm pitch) rather than the Mini-Fit (4.2mm). I might be hesitant to use connectors like that due to the difficulty of providing suitable strain relief to the entering cable. If this is an internal component or something where the connector isn't exposed to the cruel outside world it could be fine, but I'd be concerned about anything that might get rough handling. Without a shell that firmly grips the overall cable, the crimp terminals will have to bear ALL of your mechanical load.Switchcraft make barrel connectors with threaded locking nuts that are pretty nice, but not sure if there are PC mount jacks for them.Maybe mini XLR? Or regular XLR if you've got a lot of space to burn. Switchcraft TRA3M connectors are rated 5A.

author: prasimix
author_rank: Unknown
timestamp: August 03, 2016, 11:54:41 am
content: That's good point ajb. It's not the same if connector belongs to internal or external wiring. I suggested Molex for internal (inside enclosure) application.

author: ConKbot
author_rank: Super Contributor
timestamp: August 03, 2016, 02:37:51 pm
content: Switchcraft 767K on the cable mating to a switchcraft L722RA PCB mount connector?http://www.switchcraft.com/Documents/NPB%20575%20-%202.1mm%20plugs.pdfUses a 2.1mm plug, good for 5A, locking ring to secure it.
Choosing a proper shunt resistor - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: June 11, 2021, 04:21:44 pm
content: Im having trouble choosing a shunt resistor, i could not settle on a value im am comfortable with. I would like like to measure current of 0-15amps 12v or 24v load with accuracy of 0.05 amps . the adc is aADS1115 16bit ADCA 1 Ohm shunt would be to high at 15Amps it would be dissipating 225 W of heat (P= 15*15*1)A 0.1 ohm would still be a bit high because we would need 22.5W of heat dissipation.A 0.01 ohm is a bit more compelling 2.25W of heat dissipation, This would be ideal for me since the voltage it will be dropping at 0.01A is 0.12mV at 12V which they reportedly say that the ads1115 can read. My problem though is 2.25W is still quite hot, and i dont want to place a heatsink . Would these resistor survive without a heatsink at the theoretical max of my load, these are all 5W rated resistors.resistor 1resistor 2resistor 3which one is better?I could always go 1 step down further to 0.001 Ohms but the problem im facing with that is at the resistor will drop 0.05mV at 0.05A which i doubt the adc can handle that low voltage

author: ogden
author_rank: Super Contributor
timestamp: June 11, 2021, 04:30:02 pm
content: Quote from: drakejest on June 11, 2021, 04:21:44 pmConsider amplifier.https://www.ti.com/amplifier-circuit/current-sense/products.htmlhttps://www.analog.com/en/products/amplifiers/specialty-amplifiers/current-sense-amplifiers.html

author: SebastianH
author_rank: Regular Contributor
timestamp: June 11, 2021, 04:33:40 pm
content: You could always use one (or two) precision opamps to amplify the voltage by e. g. 10 or 100. As a starting point you could take a look at the opamps in the EEVBlog µCurrent. Different current range, but that doesn't really matter too much.It certainly depends on what bandwidth you need and so on. To me 10mOhm sounds reasonable, with a good Amp 1mOhm should also be feasible.

author: drakejest
author_rank: Regular Contributor
timestamp: June 11, 2021, 07:22:32 pm
content: I had a second look on prices on differential amplifiers i thought it made no sense since i had to pay 3$ per chip , but it turns out there for current sensing purposes and are like 0.3$ dual channel already...EDIT: I dont even need the ADS1115 anymore because most current sense amplifier outputs single ended reading and can use the onboard by the mCU

author: bob91343
author_rank: Super Contributor
timestamp: June 11, 2021, 09:31:26 pm
content: Don't forget the loss of accuracy due to the higher temperature of the shunt.

author: Zero999
author_rank: Super Contributor
timestamp: June 11, 2021, 09:57:32 pm
content: How about using a Hall effect transducer, rather than a resistor? It has the advantage of not dropping and voltage and isolation.https://tpe.group/en/electronic-components/current-sensors/hall-effects-sensors/hall-effect-sensor-bjhcs-sy-15a/
Choosing a right FET or IGBT for this application - Page 1
Forum section: electronics / projects

author: XaviPacheco
author_rank: Regular Contributor
timestamp: August 23, 2019, 01:25:32 pm
content: Some caveats about the circuit attached:1. The input ranges from 100 to 600VAC.2. The coil L1 has a DC resistance of 300 Ohms.3. It's oversimplified to show the concept. SW1 is a SCR. When SW1 is open, the load should not draw more than 10 mA at worst. Normally about 4 mA. When SW1 quickly closes, the load gets bypassed, and a higher current will flow through the coil L1 until the supply is cut. The coil should trip the power supply as soon as possible to avoid FET overheating. Once the supply is cut off, the only way to turn it on is manually. I mean, the coil has to be reset manually.4. The FET is configured as a current limit. This mean it's always On, not switching. So I have to make sure I don't go outside the minimum and maximum current limits.How do I do the right power calculations to find a suitable transistor? This is what I think:- I would need a high VDS breakdown. At least 1200V for the case when the input is 600VAC. It gives about 848VDC. I can add TVS diodes across VDS to protect the FET.- When SW1 is open, VDS is high. Supposing the load draws 5 mA, P = 5 mA x 800V = 4W- When SW1 closes, VDS gets a bit smaller, about 400V. This yields P = 1.2A x 400V = 480W!! But this is a very short pulse. Let's suppose the trip coil cuts the supply in less than a second.- Adding a resistor in series with the coil would reduce the stress over the FET I think.What would you suggest?