hybridfree/eevblog-posts huggingface dataset:
Chosing voltage reference for MCP3913 ADC - Page 1
Forum section: electronics / projects

author: Vex
author_rank: Newbie
timestamp: January 20, 2020, 03:45:13 pm
content: Hi everyone,I'm having trouble understanding how to connect the voltage reference to the MCP3913 (http://ww1.microchip.com/downloads/en/DeviceDoc/MC93913-Data-Sheet-DS20005227B.pdf).I have to connect a bipolar signal +/- 1V, with respect to AGND, on all 6 channels. VREF pin of the ADC can't be connected to the voltage lower than -0.6V with respect to AGND. How can the ADC measure -1V then?

author: iMo
author_rank: Super Contributor
timestamp: January 22, 2020, 10:09:48 pm
content: The ADC inputs are "differential". Also both IN+ and IN- should stay within AGND and AVDD.An example:IN+ IN- result2.0 0.8 1.21.5 1.5 0.01.0 1.5 -0.50.3 2.4 -2.1

author: AE7OO
author_rank: Regular Contributor
timestamp: March 11, 2020, 03:57:27 am
content: Actually in this case the MCP3913(Like the MCP3911 which I use) can measure +/- .6V referenced to AGND. Max input is +/- 2V, but signals outside of the +/- .6V range won't be very accurate. They do caution about holding inputs below AGND for any length of time, or if the internal clock is not running.As far as the voltage reference goes, what kind reference are you using that has better specs(9ppm/C tempco) than the internal? Beating the internal VREF is hard because at that level everything counts, how long your traces are, how clean the board is, solder type, etc. These are not like some MCU vrefs that might have a 500ppm/C tempco or worse, where adding even a $2.00 external reference makes a big difference.

author: AngélicaMX
author_rank: Newbie
timestamp: March 23, 2023, 01:55:32 pm
content: Even using the internal reference, can the MCP measure negative voltages of up to -0.6V?We don't need to put any negative sign in the REF-?
Christmas LED strips. - Page 1
Forum section: electronics / projects

author: robjodicarter
author_rank: Regular Contributor
timestamp: October 21, 2018, 02:50:15 pm
content: So what I'm going to try to do is the easiest way to hook up a total of 5 strips of rgb's. They will be in 3 different places so 3 different channels but I want to use only one remote to control all the lights. Is that at all possible? And if possible to be able to alternate red and green for Christmas and such. If not it's Arduino I go.Thank you allRobSent from my PH-1 using Tapatalk

author: madires
author_rank: Super Contributor
timestamp: October 21, 2018, 03:06:46 pm
content: Same color program for all strips? Or different programs for each place? Or do you mean three controllers and one RC?

author: robjodicarter
author_rank: Regular Contributor
timestamp: October 21, 2018, 03:15:01 pm
content: So 3 windows on one channel, one channel door and one channel on gutter. All independent channels to program or I can sync them to the same color. Just need to find a remote that allows me to change the one channel at a time if possible.Sent from my PH-1 using Tapatalk

author: madires
author_rank: Super Contributor
timestamp: October 21, 2018, 03:32:13 pm
content: You can buy cheap RGB controllers with an IR RC from China, but you might be not very happy with the programs available. Or maybe build custom ones (µC with three PWM channels, FETs, an IR receiver module plus one universal RC).

author: robjodicarter
author_rank: Regular Contributor
timestamp: October 21, 2018, 03:33:58 pm
content: Yeah, I was just going to go Arduino but where is a good place to get sketch's for LED strips. Do you know?Sent from my PH-1 using Tapatalk

author: madires
author_rank: Super Contributor
timestamp: October 21, 2018, 03:43:42 pm
content: Have you tried to search for "arduino RGB strip"?

author: robjodicarter
author_rank: Regular Contributor
timestamp: October 21, 2018, 03:45:26 pm
content: Yeah they show up as addressable LED's, that is fine I'm just trying to find a collection of sketch's to dig thru and find one that I can tune to my needs.RobSent from my PH-1 using Tapatalk

author: Twoflower
author_rank: Frequent Contributor
timestamp: October 21, 2018, 04:05:13 pm
content: How about using ESP8266? You can use the WLAN functionality to sync them and they're cheap. Or using Z-wave for syncing the individual devices.
Christmas light circuit reverse engineer - Page 1
Forum section: electronics / projects

author: pyrohamish
author_rank: Newbie
timestamp: January 06, 2019, 06:34:08 am
content: I'm trying to reverse engineer a set of battery / solar Christmas lights so I can program and run the lights with a ATTINY or similar.Photo of board and the schematic I've worked out attached. I think I know mostly how it works, but, what is the purpose of the voltage divider to NPN transistor?

author: exrbc
author_rank: Newbie
timestamp: January 06, 2019, 10:28:01 pm
content: switch on when solar voltage drops, turns on when dark.
christmas light controller - Page 1
Forum section: electronics / projects

author: dewalt94
author_rank: Newbie
timestamp: December 26, 2013, 08:01:01 pm
content: for a project I need a few 12v led lights strip from ebay to flash I was thinking of using a Christmas tree light controller with the button to change the sequence will this work or is there a better idea?

author: Rerouter
author_rank: Super Contributor
timestamp: December 26, 2013, 08:18:00 pm
content: you should be able to do that, though you may need to buffer its output if your driving a bigger load than it was designed for, equally finding a way to change the sequence if not already built into the device could be interesting, as it could be a micro playing out a pattern

author: dewalt94
author_rank: Newbie
timestamp: December 27, 2013, 02:34:00 pm
content: Also I forgot to say that it was originally used for rope lights which were 240v

author: Zero999
author_rank: Super Contributor
timestamp: December 27, 2013, 03:28:12 pm
content: You may be able to modify it but you need to trace the schematic and get a datasheet for the control IC.It's possible the controller IC might work from 12V but the lights could be switched using TRIACs or SCRs which will need to be replaced with MOSFETs or BJTs.

author: David_AVD
author_rank: Super Contributor
timestamp: December 27, 2013, 09:45:47 pm
content: The original 240V AC multi-function controller won't really be suitable for use with DC LED strips. Much better to use a micro (PIC or AVR) with some MOSFETs. Shouldn't be too hard to come up with a few simple patterns, especially if they don't need to dim/fade.

author: dewalt94
author_rank: Newbie
timestamp: December 29, 2013, 12:12:45 am
content: Thanks for your advice I'm new to electronics I have an arduino that's not being used so for now I will use that with some mosfets as I don't have a programmer but will probably invest in one soon then can program a chip for the job

author: ResR
author_rank: Regular Contributor
timestamp: December 29, 2013, 09:09:58 pm
content: Maybe use an electronic power supplies (plug in wall low power ones are cheap) at the output of the christmas light controller to get 12V from 230V?

author: David_AVD
author_rank: Super Contributor
timestamp: December 30, 2013, 01:43:32 am
content: Quote from: ResR on December 29, 2013, 09:09:58 pmVery bad idea. The phase controlled output of the lights controller can make switch-mode power supplied go bang in a very big way.
Christmas lights - Page 1
Forum section: electronics / projects

author: codemonkeyrawks
author_rank: Contributor
timestamp: November 26, 2010, 02:43:23 am
content: I want to drive some Christmas lights from a Arduino but not quite sure how to do it and multiplex the pins together since the arduino only has 12 pins. I am thinking of using a 12 relays and need to output 40 lines. Any Suggestions

author: tinsmith
author_rank: Contributor
timestamp: November 26, 2010, 04:48:14 am
content: Here's one. Do you really need to set it up as a 40-element matrix display? Strand lights usually don't. Common effects like the "racing" cycle tend to use sub-arrays tied to a common signal.LEDs also don't need to be at logic high all the time in order to appear on. Even a fairly low duty cycle will usually look like it's persistently lit, but you'll start losing some apparent brightness if you go too far. Because of this, a common technique for arrays of LEDs is to set up an m x n matrix and strobe over it.

author: tyblu
author_rank: Frequent Contributor
timestamp: November 26, 2010, 06:30:23 am
content: Shift registers are great for this type of low-update rate and pin count situations. 4094 is serial to parallel converter. You'll need a driver if the lights aren't LEDs, like the ULN2803A.More resources:http://www.lightorama.com/products.htmlhttp://www.avrfreaks.net/index.php?name=PNphpBB2&file=printview&t=18054

author: badSCR
author_rank: Contributor
timestamp: November 26, 2010, 06:54:55 am
content: I lave light-o-rama.... Very good company to do business with.I use there controllers for my display.I am a very happy customer, and my neighbors love my display.Buy your lights and stuff when they go 75% off for the after christmas sale.

author: House91320
author_rank: Regular Contributor
timestamp: November 26, 2010, 09:10:23 am
content: I am blanking on the name but there chips that will do this.

author: Murphy
author_rank: Regular Contributor
timestamp: November 26, 2010, 06:00:26 pm
content: Look into using solid state relays, they can be switched by just 5v.Or make your own circuitry using triacs or mosfets if you need it cheap.

author: tinsmith
author_rank: Contributor
timestamp: November 26, 2010, 09:04:53 pm
content: Quote from: House91320 on November 26, 2010, 09:10:23 amWell, there's the TLC5940 16-channel chainable PWM controller. But it's probably overkill for this.

author: oPossum
author_rank: Super Contributor
timestamp: November 26, 2010, 09:12:06 pm
content: 8 bit power shift registersTPIC6A595TPIC6B595TPIC6C595
Christmas tree - Page 1
Forum section: electronics / projects

author: VingTor
author_rank: Contributor
timestamp: December 15, 2014, 09:03:24 pm
content: Christmas tree at work. What more can I say...

author: pickle9000
author_rank: Super Contributor
timestamp: December 15, 2014, 09:06:55 pm
content: Is the structure cardboard?I'm not the Xmas type but that is very well done.

author: kolbep
author_rank: Frequent Contributor
timestamp: December 15, 2014, 09:15:12 pm
content: Love the slogan :We Are Atmeljust makes me think of 7 of Nine... She was a hottie then.{You will be AssimilatedResistance is Futile.....}

author: VingTor
author_rank: Contributor
timestamp: December 15, 2014, 10:25:26 pm
content: Some more pictures here:http://blog.atmel.com/2014/12/11/photos-only-engineers-have-christmas-trees-like-this/Seems to be some wooden frame holding everything up.

author: Seekonk
author_rank: Super Contributor
timestamp: December 16, 2014, 09:43:43 am
content: Yellow tape on the floor reminds me of where I once worked. Managers of competing projects were grabbing floor space and put yellow tape on floor. That was till the section manager went ballistic when he saw it.
Christmass lights production line  - Page 1
Forum section: electronics / projects

author: Kjelt
author_rank: Super Contributor
timestamp: January 19, 2018, 08:31:36 am
content: I know it is not high tech like P&P machines, but I do love how they made this and the pneumatic "music" from this linehttps://youtu.be/VmfA1LrUOD8

author: LaserSteve
author_rank: Super Contributor
timestamp: January 22, 2018, 04:21:31 am
content: I could spend hours watching this... thanks for posting it...Steve

author: kalel
author_rank: Frequent Contributor
timestamp: January 22, 2018, 06:30:48 am
content: Looks good.

author: texaspyro
author_rank: Super Contributor
timestamp: January 23, 2018, 02:16:17 am
content: Excellent... now American know secret secrets of Great Wall Green Christmas Tree Light Factory #19. I wonder if Great Wall Red Christmas Tree Light Factory #237 is similar?The machine is rather clever. I assumed they would have been made by some small town full of families huddled around their kitchen tables for 18 hours a day.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 23, 2018, 05:50:35 am
content: Quote from: texaspyro on January 23, 2018, 02:16:17 amThat was in 1970's. China hasn't been the low-wage-manual-labor sweatshop place for ages.

author: Kjelt
author_rank: Super Contributor
timestamp: January 23, 2018, 08:42:29 am
content: Quote from: Siwastaja on January 23, 2018, 05:50:35 amI saw a docu last month that there are still child labour sites for electronics sorting in China. It is such a huge country with so many different cultures and sites.....
Chroma trap design for composite video signals - Page 1
Forum section: electronics / projects

author: badgerthing
author_rank: Contributor
timestamp: October 17, 2022, 06:02:52 am
content: Hello! I'm working on a project for the niche task of converting NTSC composite, to RGB+S. An NTSC decoder. Basically, to allow me to view NTSC sources on a PAL-only 1084S-P monitor (that also has RGBS input).For my purpose, it mustn't scale or touch framerate, and I'd prefer a high quality output, so I can't use a digital PAL<>NTSC converter off aliexpress.I have based my circuit off ON Semiconductor application note AN1019/D.It seems to be almost perfect, but the output has a ringing/overshoot artifact to the right of transitions.I believe I've narrowed this down to the 3.58MHz trap circuit. The artifacts are only visible in the correctly adjusted sweet spot. If I purposely misadjust the inductor, the artifacts blend in as the entire image gets chroma leakage.Any suggestions how I may get rid of this ringing artifact?Attached is my current schematic, including bodges I've made to fix mistakes.NTSC2RGB.pdf(157.11 kB - downloaded 76 times.)Cheers!
Chrome Octo Parts Browser App - Page 1
Forum section: electronics / projects

author: Terabyte2007
author_rank: Frequent Contributor
timestamp: July 26, 2013, 03:47:16 pm
content: I found this great web app for Chrome called "Octo Parts Browser". It uses the database at octoparts.com and gives you a nice sleek interface and quick browser access to a huge electronics database. Give it a try!https://chrome.google.com/webstore/detail/octopart-electronic-part/mblfcbmihdhgbkogmkbpokdeenjiamjg?utm_source=gmail
Chua oscillator - Page 1
Forum section: electronics / projects

author: Scigatt
author_rank: Newbie
timestamp: June 21, 2016, 05:58:20 am
content: Inthis topic, I mentioned I was working on a Chua oscillator. I'm at the stage where I could send off a design to be printed, but I may have missed something important due to my new-ness. I have attached two versions of the project files below. Included are the full BOM's from Digikey for each, but you can probably source many parts from junk.
Circuit Analysis in real world perspective - Page 1
Forum section: electronics / projects

author: Mohammad Jamiu
author_rank: Newbie
timestamp: October 18, 2020, 01:56:18 pm
content: How does the circuit analysis techniques learned in college of use in the production or designing of real life working circuit. Or is there any other idea use in companies that design electronics circuit. Thanks.

author: tggzzz
author_rank: Super Contributor
timestamp: October 18, 2020, 04:17:25 pm
content: Quote from: Mohammad Jamiu on October 18, 2020, 01:56:18 pmSounds like a homework question.It enables you to design something that works reliably and predictably, and to be able to demonstrate why that is the case.The alternatives are to copy-and-paste without understanding, or trial and error.

author: Mohammad Jamiu
author_rank: Newbie
timestamp: October 18, 2020, 08:29:05 pm
content: So for companies that design electronic kit do use circuit analysis when planing on designing new product.

author: Benta
author_rank: Super Contributor
timestamp: October 18, 2020, 08:41:58 pm
content: Quote from: Mohammad Jamiu on October 18, 2020, 08:29:05 pmYes, of course.EE is not about just soldering a couple of ICs together.You'll need to document that the circuit works a desired. And this includes circuit analysis; analog, digital or mostly both.To bring a product to market it must be functional and safe. To achieve this, your calculations and maths are crucial, otherwise lawsuits and ruinous costs may occur.

author: tggzzz
author_rank: Super Contributor
timestamp: October 18, 2020, 09:24:02 pm
content: Quote from: Mohammad Jamiu on October 18, 2020, 08:29:05 pmHow would you design a circuit with more than two components? Guesswork? Trial and (mostly) error?

author: exmadscientist
author_rank: Frequent Contributor
timestamp: October 18, 2020, 09:57:19 pm
content: Quote from: tggzzz on October 18, 2020, 09:24:02 pmOf course not, that's stupid. Everyone knows you just steal the circuit from the datasheet and then it HAS to work!(Seriously, a former colleague actually did design this way. He also wasn't careful to actually steal from the "recommended application" circuit... it was often the "parameter test" circuits that got lifted. Usually that just resulted in extra resistors in weird places. Sometimes he stole from test circuits that were intended to test the poor part to failure or destruction.The worst part is that this guy had 10 years of experience designing medical electronics....)
circuit board without the board - Page 1
Forum section: electronics / projects

author: ptricks
author_rank: Frequent Contributor
timestamp: October 21, 2012, 03:13:09 pm
content: I was harvesting parts from an old HP laserjet 4P and found an interesting board. The board that controls the motor where the laser bounces off of to the drum doesn't appear to be a board at all. The bottom is aluminum and the circuit traces are on top only there is nothing under the traces except the aluminum. Even the solder mask appears to just be paint on the aluminum. I have been in electronics quite a long time and have never seen anything like this. It looks almost like someone just printed off a circuit layout and stuck it to the aluminum.Anyone know what this type of PCB is called ?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 21, 2012, 03:46:35 pm
content: Aluminium clad PCB - used a lot nowadays for high power LEDs

author: penfold
author_rank: Frequent Contributor
timestamp: October 23, 2012, 07:49:35 pm
content: I recently found a very similar board and the substrate was steel, that was rather surprising. You will find that the majority of applications where this type of board is used (excluding LEDs of course) the board will be potted or enclosed, many hybrid power modules are built on this kind of board, just encapsulated by the time you see them.

author: SeanB
author_rank: Super Contributor
timestamp: October 23, 2012, 08:11:37 pm
content: Only time I see those potted in a hybrid was for 100W plus power boards, where they were metal cored. Usec by IBM in processor assemblies on minis and mainframes.The steel boards are common in printers as power interfaces for motors, and for disk drive motor assemblies where you wanted a flat motor.

author: ejeffrey
author_rank: Super Contributor
timestamp: October 23, 2012, 11:31:36 pm
content: Eurocircuits even has an IMS (insulated metal substrate) pooling service for this.

author: jabramo
author_rank: Regular Contributor
timestamp: October 27, 2012, 10:50:36 pm
content: I used these at my coop designing 400w high power LED highbay lamps. We'd bolt them to big heat sinks with a layer of thermal paste in between.
Circuit design assistance: Quad composite camera inputs to raspberry pi  - Page 1
Forum section: electronics / projects

author: markj
author_rank: Newbie
timestamp: June 26, 2023, 02:42:23 pm
content: I previously posted in Beginners section, but it seems that there are very few commercially available products, and none that will meet my needs, so I'm asking if it is appropriate to ask this forum for design help with this project?Prior post:https://www.eevblog.com/forum/beginners/how-to-do-this-multichannel-palntsc-video-stream-into-single-usb-to-rasppi/Restating project scope:Multiple (4) composite camera inputs multiplexed into a Raspberry Pi environment. I'm initially looking for hardware design input (feasibility, functional block diagram & detailed electrical design), and then will write R-Pi software for that hardware environment to allow image manipulation and interface to a smart device. I've read that R-Pi is not a good real-time environment, that's OK as I think I'd like to cycle through the images one at a 1/2 sec or so rate.Thanks in advance for any guidance and input. Please feel free with questions if I have not been clear.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 28, 2023, 10:23:57 am
content: Get a buffered video mux ic. Add termination resistors and gain set if needed (usually 6dB). Dont get hung up on precise gain set resistor values, just use something close.A neat pcb layout is a good idea @10MHz.eg LMH6574, 2 GPIO, 4x 75R 4x 75R BNCs?www.ti.com/product/LMH6574?keyMatch=LMH6574see 7.1, Functional Block Diagram in datasheet. Thats it.The AD8174 is very similar- you can even get a ready made pcb with all the stuff on it for $30 from AD.https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/eval-ad8174.html#eb-buyMAX4311?

author: jwet
author_rank: Frequent Contributor
timestamp: June 29, 2023, 12:33:53 pm
content: Google this on Ebay- 4-Channel CCTV To USB DVR Adapter Camera Quad Video Switcher For PCThis plugs into USB, takes 4 composite inputs and diplays them- its $18. Good place to start. This is the basis of a cheap secruity DVR.
Circuit design for camera switch - Page 1
Forum section: electronics / projects

author: Hornnumb2
author_rank: Regular Contributor
timestamp: October 09, 2025, 02:10:04 pm
content: I have 2 cameras and only 1 input, could a switching circuit be designed to change between the 2? Its on a 24 Chevy Silverado with a back up camera, but when backing up to fifth wheel the tailgate has to be down making the tailgate camera useless. I would like to move a camera to the bottom of back glass for when tailgate is down and be able to switch between them. The camera connectors are Fakra plugs. The cameras are just 2 conductor cables. is there a chip that would just switch between 2? Thanks

author: Andree Henkel
author_rank: Regular Contributor
timestamp: October 09, 2025, 02:34:49 pm
content: you need a DPDT (double Pole double throw) switch configuration, exist as mechanical switch, relay or analog switches. To little info given on the transmitted signal to know, if or what analog switch may be feasible.

author: Hornnumb2
author_rank: Regular Contributor
timestamp: October 09, 2025, 02:46:21 pm
content: I think the signal is LVDS, just need it to pass through,

author: Andree Henkel
author_rank: Regular Contributor
timestamp: October 09, 2025, 04:55:21 pm
content: so you would need a LVDS 2 Lanes -> 1 Lane MUX (each lane has two electrical wires)like this:https://www.digikey.de/de/products/detail/analog-devices-inc-maxim-integrated/MAX9176EUB-T/3517020

author: Hornnumb2
author_rank: Regular Contributor
timestamp: «Reply #4 on:Todayat 02:47:45 am »
content: Ordered that component, what lines will need to be hooked up for a pass through device? Thanks for the help. Michael

author: Andree Henkel
author_rank: Regular Contributor
timestamp: «Reply #5 on:Todayat 11:35:03 am »
content: read data sheet.read data sheet again.try to draw a schematic of the circuit to be builtshow it herefrom what I read, you need to connect all 10 Pins, you need a 3.3V Supply, you need two decoucling capacitors, two input terminating resistors, one on each input pair.you need to determine for the camera link pairs which wire is Data+, which is Data-if there are still questions feel free to come back and ask

author: Andree Henkel
author_rank: Regular Contributor
timestamp: «Reply #6 on:Todayat 12:05:06 pm »
content: here is a search on msop-10 adapter boardshttps://www.google.com/search?client=firefox-b-d&q=msop+10+adaptertry to select one where the traces to the IN0+/-, IN1+/- and Out+/- pins are as short as possible and the traces within each of the three pairs have as close as same length as possible.you can solder the two 100Ohms termination resistors and the two decoupling capacitors 100nF and 1nF on same board,and maybe a LDO to generate 3.3V from 12V car battery voltage too.this may work or may not. It may be necessary to do actual PCB layout with 100Ohms differential routing and trace length matching
Circuit diagrram TP4056 and DW01A - Page 1
Forum section: electronics / projects

author: Wilson__
author_rank: Frequent Contributor
timestamp: April 23, 2024, 09:47:52 am
content: Appreciate circuit diagram for the popular Li ion cell charging board using TP4056 and protection chip DW01A. I need to make a custom board incorporating the circuit since 30mAh cell does not have build-in protector board. Many thanks

author: MLXXXp
author_rank: Frequent Contributor
timestamp: April 23, 2024, 04:17:26 pm
content: https://support.envistiamall.com/kb/tp4056-dw01a-microusb-5v-1a-18650-lithium-battery-dual-function-charger-board-with-protection-module/

author: Wilson__
author_rank: Frequent Contributor
timestamp: April 24, 2024, 08:02:36 pm
content: many thanks. great information
Circuit for check PSU positive and negative rail - Page 1
Forum section: electronics / projects

author: firstcolle
author_rank: Regular Contributor
timestamp: December 12, 2017, 01:03:25 pm
content: hiI'm designing a PSU with 3 rails, +15 -15V for the analog section and +5v for the digital one. the AC comes from 2 secondary of the same transformer. the 2 GND are separated and will be connected only at one point near the A/D IC.I want to implement a check on the analog rails.. something like 5v if the rails are upper certain voltage (+14 / -14 for example).the signal could be going to the microcontroller or to a relay to enable or not a certain part of the circuit.is there an easy way to do that??I thought to use BJT's in on/off config but at this point analog GND and digital GND are connected together and I don't want that.could 2 optocouplers help? obviously, the one on the negative rail must have the GND on the cathode and -15v on the anode of the driving led. could it work?thanks

author: David Hess
author_rank: Super Contributor
timestamp: December 12, 2017, 02:58:05 pm
content: The brute force way is to use window comparators.The three supplies could be combined with 3 resistors to produce a zero volt "balance" output. Then if any of the three are wrong there is an indication of a problem.
Circuit for checking "protective earth" presence - Page 1
Forum section: electronics / projects

author: razielfirst
author_rank: Newbie
timestamp: January 12, 2022, 04:56:52 pm
content: Hi all, I'm new on the forum but a long time EEVblog follower.I am designing an EVSE (EV charger) control board, which for safety reasons must constantly check the correct connection of the ground/earth cable.If the earth connection is not present during the start-up or if disconnects during operation, the controller must perform the operations necessary to secure the system (stop charging the vehicle, activate an alarm, etc.).I cannot find many examples of how to best perform this test, the most used method seems to be to "inject" a few milliamps from the phase (230V AC) to ground through an optocoupler.If the current flows the ground is good, otherwise it is not.(see the first circuit)I don't like this simple design because in case the ground is not present it permanently puts 230v on the grounded surfaces, even when the control board is turned off.I modified the circuit by adding a relay that can be opened in case of fault (or when the card is off).Do you see any critical issues in this design? I would like to design this part of the circuit in the best possible way.Thank you.(the negative rail/GND of the control board and "protective earth" must be connected together by standard)

author: jonpaul
author_rank: Super Contributor
timestamp: January 12, 2022, 05:36:19 pm
content: what is EVSE?you make a DIY one pc or design for commercial sale?j

author: razielfirst
author_rank: Newbie
timestamp: January 12, 2022, 05:44:59 pm
content: An EVSE (electric vehicle supply equipment) is also known as EV charger.Like this oneI'm designing it for commercial sale.

author: jonpaul
author_rank: Super Contributor
timestamp: January 12, 2022, 07:55:00 pm
content: 230V thru a 330K R is ~ 666 ua small enough to be a leakage current and less than a VDE Y cap.The added relay introduces a single pint fail safe issue.In the USA, the earth connection must be tested for resistance during compliance. For various power levels a max resistance is specified, not merely presence of absence.As there is safety and liability in such designs, strongly recommend:a/ Consult the standards and regulatory rules applicable in your countries and area of sales, eg VDE /TUV in Germany, IEC in EU, UL/ETL in USA.b/Learn the safety and EMI compliance requirements OR retain services of an experienced compliance engineerc/ Design for redundancy and fail-safe, no single point failures.d/ Perform extensive testing at limits of specs.Bon ChanceJonNOTICE I AM NOT LIABLE FOR ANY CONCEQUESNCE OF THIS NOTE, REVIEW ALL DESIGNS AND IMPLIMENTATION WITH APPROPRIATE ENGINEERING AND LEGAL ADVISORS
circuit for detecting a 220v AC signal - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: September 11, 2021, 02:04:07 pm
content: I would like to create a circuit that detects if there is 220v AC present on the inputsThe requirements i set out to achieve are:Must be able to detect 220v AC that is switched less or equal to 5HzMust be robust and safe for the electronics on the other side, so can withstand surges and other factors typical mains voltage is subjected to.Outputs are already filtered out meaning 3.3v DC for 220v is present and 0v DC if there is none, not a square wave looking signal for "on"Looking through circuits online i found this moduleIt has an optocoupler which provides isolation which i think is good, but i do not like that its using an electrolytic capacitor which is very prone to failure especially in 220v AC setting when surges are not uncommon.another circuit which i think i like better since it does not use an electrolytic, I think i would need to add a MOV to protect from surges and there are cheap full bridge rectifier like theMB10sCan anybody suggest an improvement to the circuit or a better type of circuit. I think a good place to imitate a circuit are those used in industrial applications as they have stricter requirements does anybody know how its done there?

author: jmelson
author_rank: Super Contributor
timestamp: September 11, 2021, 11:09:08 pm
content: Your 390 K resistor will only supply 0.8 mA to the LED, is that enough to turn it on?I'd use two (or more) SMT resistors in series, so the voltage across each is reduced. Also, keep them away from the mounting screws.The 390K resistor will only dissipate about 1/4 W PEAK, average should be much less.Jon

author: james_s
author_rank: Super Contributor
timestamp: September 11, 2021, 11:12:52 pm
content: Either of those circuits looks like it would work fine, you could replace the capacitor with a higher quality part if you are worried about that. You could also make your own opto coupler using a 220V neon indicator and a phototransistor.

author: floobydust
author_rank: Super Contributor
timestamp: September 11, 2021, 11:20:50 pm
content: For industrial applications, a problem can be the minimum voltage threshold. If you have 80VAC do you want the circuit working? People add a series zener or resistor across the LED to shift this. PLC's will add a two transistor constant-current source.I use sensitive 1mA opto-couplers i.e.MOCD217to keep heat down. The resistor comes first, acting as a fuse. Otherwise, a shorted bridge causes smoke.Another zero-cross (only) circuit discussed here:https://www.eevblog.com/forum/projects/mains-zero-crossing-detection/msg3469950/#msg3469950

author: DeanA
author_rank: Regular Contributor
timestamp: September 12, 2021, 12:34:03 am
content: There is:MID400: AC Line Monitor Logic Output OptocouplerWhich I have used successfully in a commercial application for 230VAC.https://www.onsemi.com/products/interfaces/high-performance-optocouplers/specific-function-optocouplers/mid400
circuit for detecting ground isolation? - Page 1
Forum section: electronics / projects

author: ftransform
author_rank: Frequent Contributor
timestamp: June 22, 2013, 01:03:31 am
content: So I am going to build myself a isolated variac, with a switch to enable and disable the isolation. However, I would like to add some kind of circuit which will indicate if the output is isolated, in case the switch has a failure.... I don't want to blow up a scope.does anyone have any ideas? Other then a knife switch...

author: David_AVD
author_rank: Super Contributor
timestamp: June 22, 2013, 01:13:33 am
content: Just curious - what's the reason for wanting to disable the isolation?

author: ftransform
author_rank: Frequent Contributor
timestamp: June 22, 2013, 01:25:43 am
content: Quote from: David_AVD on June 22, 2013, 01:13:33 amIn case I want to work on something that could benefit from a grounded housing, I am not sure it seems that in other variac threads people in some cases voiced opinions against isolation, maybe I can hook up a GFIC to it, so its safer in un-isolated mode (for me and not my equipment).furthermore, you get better CMRR when the ground is connected. It would just be a switch that connects earth ground to the transformer output neutral.I guess you can try to detect the capacitive voltage, using a high impedance adc, but it seems complicated.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 22, 2013, 04:41:31 am
content: Obviously by the "transformer output neutral" you mean the end of the secondary which connects to thatsocket pin which is normally neutral.Connect a neon globe between the other side of the secondary & the Earth pin.When the switch is OFF,the neon will be OFF,when the switch is ON,the neon will glow.

author: ftransform
author_rank: Frequent Contributor
timestamp: June 22, 2013, 04:44:10 am
content: ah damn how did I over look that. I was going to connect a ADC to see if the voltage is like 0 or 120V (connected).LOLi need to sleep lol!
Circuit for temperature controll - Page 1
Forum section: electronics / projects

author: Arcadium
author_rank: Newbie
timestamp: March 21, 2022, 06:45:13 pm
content: Hello,I am making a project where I try to control heating element with type K thermocouple and AC heater. I have previously did one with DC heater, but now I need some professional help.My circuit for DC heater worked, but I have little experience in circuit design and this one will have 50 or so heater/thermocouple segments. (heater and thermocouple I have:https://www.aliexpress.com/item/32869555292.html?spm=a2g0o.order_list.0.0.21ef1802IzJAHI).It should be not too expensive and reliable. I will use Arduino microcontroller and would like to use PWM pins to control it, for the reading MAX6675 chip can be used.If it's possible to make a closed loop system without using microcontroller it would be perfect, but I don't think it can be done cheap for such quantity.If someone could come up with the schematic and components that would be great, I'm willing to pay a bit if I can get schematics and BOM.I know that forum is more for helping to learn and come up with solution and not for providing one, but in this project I'm trying to program Arduino chip directly and there is a lot to learn there(first time with bit operations). I don't want to introduce a lot of variables because I'll go crazy trying to find what's wrong.Anyways, even the general advice is welcome, worst case scenario I'll try to make it myself.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 21, 2022, 08:49:57 pm
content: One can build a temperature regulator the old analog way. If only crude proportional control is needed howver analog control could be very viable. So it depends an the required accuracy and speed. However this gets a bit cumbersome with a PI or PID regulator and the often relatively long time constants (e.g. > 1 second) for the thermal system and tuning may need soldering. So it makes sense to use a µC. Another reason to use a µC would be if more than just a constant temperature is needed, like some ramps or additional functions.For a cost effective system, especially with multiple channels, one could get away without the relatively expensive MAX6675.One may consider an external ADC, or maybe just external amplification.The required speed of the system would determin how many channels a single µC could serve.There are some relatively cheap temperature controlers from China, that may do the job.
Circuit Identification - Page 1
Forum section: electronics / projects

author: yogece
author_rank: Contributor
timestamp: November 03, 2018, 02:44:11 pm
content: Hi All,Out of curiosity i would like to know about the 2 IC's used in the 10K NTC to 0-5V / 0-10V converter module such ashttps://www.brightwinelectronics.com/product/ntc-thermistor-to-voltage-converter-10k-ntc-0-10v-0-5v-linearity-conversion

author: rstofer
author_rank: Super Contributor
timestamp: November 03, 2018, 03:18:11 pm
content: The 8 pin chip is probably an op amp and the bigger chip is probably a microcontroller.As a guess the NTC is connected to the A/D converter of the uC and the uC does some tricky math to linearize the signal. The output from the uC is run through the op amp to provide scaling and buffering.
Circuit Identification - Page 1
Forum section: electronics / projects

author: nonsuchpro
author_rank: Contributor
timestamp: December 02, 2017, 07:12:45 am
content: Hey all,Got this in a box of old electronics from a friend. He said his dad made this but had no idea what it was. I'm thinking a motor controller maybe? The 2 can transistors are 2N3019's.What do you guys think?Thanks!

author: Ian.M
author_rank: Super Contributor
timestamp: December 02, 2017, 07:26:37 am
content: Its got a pair of 2A DC 0.5A AC relays, a quad AND gate, a dual flipflop and a 555 with a large timing capacitor, so I'd say some sort of timer or sequencer for something. The relays wont stand up to a large inductive load so if it was for motors, they,d have to be small and low voltage DC.See if the TO220 is a 5V regulator, if so, trace the wiring back to the terminal block and power it up.

author: nonsuchpro
author_rank: Contributor
timestamp: December 02, 2017, 08:18:11 am
content: OK, The first 2 terminals (right) are power and ground. When I turn it on and hit the momentary button, it turns on one side and if I hit it again it turns it off. Click it again and it turns on the other side and click again to turn off. I hear the relays clicking. So it's ON/OFF/ON/OFF. The opposite end terminals measure 3.5V whether the LEDs are on or off. The 2 middle terminals measure 15-20mv when on and 0v when off.
Circuit layout/diagram programs?   - Page 1
Forum section: electronics / projects

author: viper
author_rank: Regular Contributor
timestamp: September 01, 2025, 02:50:55 pm
content: Would like to do some initial diagrams. Not sure what programs are out there? I recall Digikey and similar had a few? If I was dreaming, I'd like to find one with a lot of prestored chips and passives.Eventually I will need to do a PCB design layout in which it would be great to use the same program. I sort of want to see what AI can do but baby steps I guess. only reason I mention is it could be beneficial to work it all in the same program.

author: eutectique
author_rank: Frequent Contributor
timestamp: September 01, 2025, 03:17:23 pm
content: There is the whole tree dedicated to EDA/CAD :https://www.eevblog.com/forum/eda/

author: Benta
author_rank: Super Contributor
timestamp: September 01, 2025, 05:01:11 pm
content: Free and very professional: KiCAD.https://www.kicad.org/

author: viper
author_rank: Regular Contributor
timestamp: September 01, 2025, 08:00:42 pm
content: Outstanding! Really appreciate it guys!
Circuit mod, non-inverting op-amp buffer with a feedback resistor? - Page 1
Forum section: electronics / projects

author: MrLikerBiker
author_rank: Newbie
timestamp: October 28, 2014, 12:37:58 pm
content: I need to modify a project that involves changing a non inverting op-amp circuit with a gain of about 16into a non inverting buffer by removing a resistor. It leaves in place the original feedback resistor (15K) instead of a direct link from the output to the inverting input. The mod appears to function OK.I realise that there will be a small voltage drop across the resistor due to input bias current. However, this something like 0.1uV. The output of the op-amp connects to the input of an ADC where 1 bit = 1mV so there shouldn't be any noticeable affect.I know I could replace the feedback resistor with a zero ohm link but I am trying to minimise the number of operations to be performed in the mod.So..... Is it going to be ok to leave the 15K feedback resistor in place?

author: Kevin.D
author_rank: Frequent Contributor
timestamp: October 28, 2014, 01:08:14 pm
content: If your happy with small bias current error then should be ok, as long as the opamp is well stable at a gain of 1 (most are, yours likely is. There's a few that aren't and need some compensation on the output ).Regards

author: LvW
author_rank: Frequent Contributor
timestamp: October 28, 2014, 02:28:52 pm
content: Yes - of course, you can realize a unity-gain buffer with such a feedback resistor.There are two error sources:* As mentioned, the small DC bias will cause a tiny dc drop across the resistor, and* The (internal) input offset voltage (see opamps data sheet) will appear (multiplied with "1") also at the output.* If you are lucky both effects reduce each other - depending on the sign of the offset voltage.* I you are not lucky, both effects are superimposed and increase the dc output more than allowed.
Circuit needed:  Speed control a 12v fan that doesn't have a PWM wire - Page 1
Forum section: electronics / projects

author: frogblender
author_rank: Regular Contributor
timestamp: November 24, 2022, 09:34:42 pm
content: The 12V DC brushless fan I want to use is not available in a 4-wire version (3rd and fourth wires of fans being TACH and PWM, of course).... but I need to speed control this fan.Anyone have a circuit to convert a standard 25kHz PWM fan signal (from a motherboard, or wherever) to switch the 12V going to my PWM-less fan?

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 24, 2022, 10:35:50 pm
content: Some motherboards let you choose between pwm and voltage regulation mode, check yours.

author: james_s
author_rank: Super Contributor
timestamp: November 24, 2022, 10:42:48 pm
content: You can PWM the voltage supply to the fan, there are small inline boxes available that do just that, or you can build something yourself.

author: frogblender
author_rank: Regular Contributor
timestamp: November 25, 2022, 08:38:49 pm
content: SOLVED: it is easy: just slap in a low-side fet or npn, a flyback diode across the fan, and you are done.See pg25 for lots of examples:https://www.onsemi.com/pdf/datasheet/adt7473-d.pdfThanks to the dudes who answered.
Circuit OCR software - Page 1
Forum section: electronics / projects

author: gkmaia
author_rank: Frequent Contributor
timestamp: December 01, 2020, 12:47:41 am
content: Is there such thing as an OCR for circuits?Something capable drawing a technical circuit out of an image of a PCB with more or less manual work to guide the OCR?

author: moffy
author_rank: Super Contributor
timestamp: December 01, 2020, 08:55:08 am
content: Not to my knowledge. It would require the PCB wiring to be known(bed of nails?) while populated. Not really practical especially with more than 2 layers. Then you would have to ID every component and orientation, surface mount components make that difficult but perhaps not impossible. Then you would have to marry the PCB wiring with the components. The PCB wiring is the real sticker.
Circuit Optimization (methods with MATLAB and APLAC WINSPICE) - Page 1
Forum section: electronics / projects

author: Scutarius
author_rank: Regular Contributor
timestamp: May 02, 2011, 02:52:21 am
content: Hi,I am taking this course ( Circuit Optimization) and I really like the idea that you can profit of MATLAB and APLAC/WINSPICE working together or at least with a little help (via .txt file)You can take a look on my last assignment (attached)As a final project it is intended to develop a good application, it seems that my ideas are just simple, I was thinking in develop an smal GUI to use MATLAB and WINSPICe more friendly with some circuit involving OpAmps/transistors, maybe an FM modulator just for say something.Do you have some project (abandoned or not) that involve optimization (gain, power, current, etc)Could you give me some help? maybe a circuit quizThank you!!!

author: Scutarius
author_rank: Regular Contributor
timestamp: May 02, 2011, 03:14:31 am
content: I also have a project that involves accelerometers, and I also have a job as a PCB designer, not a big deal just simple PCBs but that would be a great opportunity for go beyond.
circuit protection - Page 1
Forum section: electronics / projects

author: Terry Bites
author_rank: Super Contributor
timestamp: March 16, 2022, 12:40:50 pm
content: For those interested in such things, mouser are o ffering this guide.https://emea.info.mouser.com/circuit-protection-guide?utm_source=elecdesign&utm_medium=email&utm_campaign=3p-21.0901-leadgen-circuit-protection-refguide-emea-elecdesign-emea-en&cid=email&pid=elecdesign

author: MegaVolt
author_rank: Frequent Contributor
timestamp: March 16, 2022, 03:07:01 pm
content: Sign up and get a useless data sheet. Hold it.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 17, 2022, 09:38:04 am
content: Its not a data sheet- its just a simple guide. Useless to you no doubt, but it maybe of interest to others.
Circuit rendition - thanks for the advice. - Page 1
Forum section: electronics / projects

author: rickey1990
author_rank: Regular Contributor
timestamp: January 27, 2016, 01:00:13 am
content: My project update, I have posted a few renditions of the board, took some advice from here and I have also been talking to a few volunteers at hobbyist groups in the UK, Lots of different age ranges with different preferences regarding microcontrollers, Pic, atmega's, 8051's, Also I have been speaking to a few people who are not electronics enthusiasts but want to jump on the band wagon. Im trying to keep the board as modular as possible,but not cluttered. This is because the person will have to make physical connections between the inputs and outputs of each module with jumper leads. I am also currently developing a website, With information on each section of the board, explaining how it functions and its layout. Starting off simple and increasing in complexity. There are also calculators for the working out of resistor values.A few people have asked me about the cost, my budget for the project is £300 ($430) This will cover the design costs,great chap in sri lanka does my work. The printing of 100 boards and all the components from china for those 100 boards.My changes are, instead of a VGA port, there will be a SD card interface with support circuitry (up to 2gb). A oscillator circuit, A reset circuit for PICS & ATMEGA'S, but can be modified to work with 8051's. The outputs of the max232 is left unconnected so Bluetooth and wifi devices can be used along with the two rs232 ports. Space for filter capacitors. Additional + & - pins. A RGB led, mounting holes. small prototyping are and space for icsp/10pin jtag.I am hoping to sell the kits for £25. Including jumper wires,Choice of microcontroller, RGB led, All the headers, Max232, 2 rs232's,SD card slot pretty much everything except the SD card and power supply.

author: LukeW
author_rank: Frequent Contributor
timestamp: January 27, 2016, 03:06:58 am
content: Why are you using an RS-232 connection to the PC in 2016? Many people would struggle to find a computer with an RS-232 port.Using resistive dividers for the SD card is a bit rough... it can work at low speeds, depending on the input and output impedances and the parasitic capacitance on the SPI lines, but using an IC is better.Or, better still, just run the microcontroller at 3.3V logic levels with nothing to translate.