hybridfree/eevblog-posts huggingface dataset:
Homebrew CPU/Minicomputer system from 74HC logic project - Page 1
Forum section: electronics / projects

author: homemadecpu1986
author_rank: Contributor
timestamp: September 08, 2020, 03:19:53 am
content: Hello friends.I just wanted to share my project. It's a 16bit CPU and computer system, built from 74 series logic.It is 16bit, and has up to 4MB of ram. It has virtual memory such that each process can access up to 64KB of memory. A total of 256 processes can run in parallel including the kernel supervisor process.It is built on wire wrap boards and uses around 260 IC's. It is wired by hand.It has 2 serial ports right now, one is connected to the internet.Here is a quick video about it:It has no operating system right now. Only a simple monitor. I am working on it!It is connected to Telnet on address 74cpu.uk.ms on port 51515. I invite you to visit and play around. You can run your own programs there too.I am working on getting a compact flash interface and a floppy drive too for fun.Thank you for looking.

author: ale500
author_rank: Frequent Contributor
timestamp: September 09, 2020, 04:39:21 pm
content: Great work !Do you have some schematics, opcode description, architecture to share with us too ?

author: cheeseit
author_rank: Regular Contributor
timestamp: September 09, 2020, 05:54:34 pm
content: Very cool, you just gained another subscriber. I second the request for more details.

author: homemadecpu1986
author_rank: Contributor
timestamp: September 10, 2020, 08:39:20 am
content: Hi there. Everything is here:https://github.com/Pconst167/homemade_minicomputer_latest
homebrew psu - Page 1
Forum section: electronics / projects

author: m3vuv
author_rank: Super Contributor
timestamp: January 27, 2022, 06:57:45 pm
content: Hi all,im building this psu,but instead of using the lm723,i am using an infinion sg3532 ic,the thing is i dont have a 500 ohm pot for r11,i only have a 1k pot,what difference will that make if any,just so i know if i need to order one,the one i have is a 1k 10 turn wirewound.TIA

author: xavier60
author_rank: Super Contributor
timestamp: January 27, 2022, 11:12:07 pm
content: Quote from: m3vuv on January 27, 2022, 06:57:45 pmThe 1K Pot wont matter at all. The current sensing input is 100mV on the sg3532 so the CS resistance can be made much lower. A resistor should be put in series with one end of the Pot to set the upper current limit of the range.The data sheet also shows "FIGURE 9 - HIGH EFFICIENCY LOW VOLTAGE REGULATOR". They mean Low Drop Out voltage.

author: xavier60
author_rank: Super Contributor
timestamp: January 27, 2022, 11:29:36 pm
content: Or the CS resistance can be left as it is to give a range starting at about 400mA.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 28, 2022, 12:33:39 am
content: You have posted somewhere else the same question in 2018 ??

author: m3vuv
author_rank: Super Contributor
timestamp: January 28, 2022, 02:36:59 am
content: i dont remember that.

author: xavier60
author_rank: Super Contributor
timestamp: January 28, 2022, 02:58:30 am
content: I have not been able to find the input common mode range on the sg3532.If it includes GND, this will allow the output voltage to be adjust to zero volts without needing to add extra tricks to the design.
Homehub 3.0a UART OpenWRT - Page 1
Forum section: electronics / projects

author: paul_g_787
author_rank: Frequent Contributor
timestamp: April 23, 2025, 07:42:58 pm
content: I want to flash some old Home Hub 3.0a routers to use as access points. The problem is the tutorial is deleted as this site is no more:https://openwrt.ebilan.co.uk/viewtopic.php?f=5&t=104I have the firmware from here:https://openwrt.org/toh/bt/homehub_v3aI have already successfully flashed multiple homehub 5s using UART. The problem I have is finding the UART points on the PCB on the homehub 3.0a.Does anyone have access to the tutorial or a pic of the UART points?I have attached a pic of the PCB. Maybe someone can help me identify the pins?

author: Monkeh
author_rank: Super Contributor
timestamp: April 23, 2025, 07:52:07 pm
content: Quote from: paul_g_787 on April 23, 2025, 07:42:58 pmThere are pictures right there on the OpenWRT wiki.
Homemade 2.5W Laser Build - Page 1
Forum section: electronics / projects

author: pknoe3lh
author_rank: Regular Contributor
timestamp: March 06, 2017, 10:04:35 am
content: Hey Everyone!Want to share my Home made Laser cutterYouTube:https://youtu.be/KK3RJVtJfsU(English Version)https://youtu.be/dvDvydRWGTI(German Version)Github:https://github.com/pknoe3lh/laser_hardware(Hardware Design)https://github.com/pknoe3lh/grbl-Mega(Firmware)Photos:https://goo.gl/iJYk0H(Electronic)https://goo.gl/photos/PYZxVB97AwpBpuJi8Parts:http://www.banggood.com/TB6600-Upgraded-Version-32-Segments-4A-42V-5786-Stepper-Motor-Driver-p-981997.html(Motor Driver)http://www.banggood.com/445nm-2_5W-2500mW-Blue-Laser-Module-With-Heatsink-For-DIY-Laser-Cutter-Engraver-p-993521.html?rmmds=myorder(Laser)GreetingsPatrick

author: pknoe3lh
author_rank: Regular Contributor
timestamp: March 06, 2017, 12:05:40 pm
content: This video was actually made earlier
Homemade basic component tester for oscilloscopes - Page 1
Forum section: electronics / projects

author: WackyGerman
author_rank: Regular Contributor
timestamp: July 13, 2014, 09:19:03 am
content: Hi there ,here ist my really first start project in electronics . I bought a C30 oscilloscope made by Grundig from Ebay and there is no component tester inside this unit . So I decided to build one by myself . The cost of the ordered parts were less than 30 € and the schematic is really really easy . You can see on the pics that it is all built in in one housing , the C13 socket with 2 pole switch and fuse for the source , the transformer 230V/9V 155mA , the 20k resistor , the control light , the bnc sockets to connect to the oscilloscope and the banana jacks to connect the test object .Primany circuit and secondary circuit are installed seperately and all contacts of the primany circuit are shrunked for safety reasons . It made lots of fun to build it and I checked it out and it works well .For myself it was a little trip in the past . When I learnt my job electrician in the firm they also repaired audio stuff like radios and TV s and the guy who did the job shew me how to look for defective diodes and transistors with an oscilloscope . I remember it was a hameg 400 series with built in component tester . He was an electronic student and a really clever guy .Here are some pics of my homemade component tester and the schematic for that
Homemade Enclosures - Page 1
Forum section: electronics / projects

author: Chiaroscuro
author_rank: Newbie
timestamp: April 19, 2015, 04:16:37 pm
content: Here is an easy way to make your own simple enclosures of any size or shape using four basic tools. A Jigsaw, file, vice Folder and sandpaper.This box that I made today cost me nothing as the aluminium was used material.

author: SeanB
author_rank: Super Contributor
timestamp: April 19, 2015, 04:33:38 pm
content: Very nice that.

author: kurt
author_rank: Contributor
timestamp: April 19, 2015, 07:13:58 pm
content: Nice job

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 19, 2015, 08:16:13 pm
content: Nice, but there is nothing supporting the front plate, won't it smoosh under use? I'd have put the side panel under the plate, or added flanges.

author: Chiaroscuro
author_rank: Newbie
timestamp: April 19, 2015, 08:46:08 pm
content: Quote from: Alex Eisenhut on April 19, 2015, 08:16:13 pmThat is a good idea, I will probably improve and modify it and add more support to the front. It is solid in it's current form but if it is cut then it will weaken it.Thanks for the nice comments on it.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 19, 2015, 09:05:26 pm
content: Quote from: Chiaroscuro on April 19, 2015, 08:46:08 pmI just wish I had the room for a decent workshop area.

author: Chiaroscuro
author_rank: Newbie
timestamp: April 19, 2015, 09:13:30 pm
content: Me too, My place is tiny, but what can you do?

author: void_error
author_rank: Frequent Contributor
timestamp: April 20, 2015, 07:35:39 am
content: I wish I could buy aluminum plate in something smaller than the 1x2m size sheets where I live... but nobody sells anything smaller -.-
Homemade esr meter! - Page 1
Forum section: electronics / projects

author: Tita
author_rank: Contributor
timestamp: June 15, 2013, 06:20:35 am
content: Hi from Romania!This is my first post on the forum... .and i like to present to you my homemade esr meter!The original schematic,pcb and ideas can be find in this web site:http://members.shaw.ca/swstuff/esrmeter.htmlI have been using shockley diode for the brake rectifier ,because the 1n4148 diode was having a high voltage drop in the original schematic!!Some pictures:http://imageshack.us/photo/my-images/801/966k.jpg/http://imageshack.us/photo/my-images/854/7wuz.jpg/http://imageshack.us/photo/my-images/593/bqmx.jpg/The two leads go to the analog multimeter!http://imageshack.us/photo/my-images/12/multimeteryx360trd.jpg/P.S Sorry for the crap language...right now i'm learning how to write !

author: InterestedTom
author_rank: Regular Contributor
timestamp: June 19, 2013, 03:36:33 pm
content: I really like the analog approach. And by only using one high voltage rated part you really keep the cost down, nice one.

author: Tita
author_rank: Contributor
timestamp: June 19, 2013, 04:51:56 pm
content: Thanks!Now i'm working on the second esr meter.. O0.to be more portable !

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 19, 2013, 05:00:23 pm
content: Tita,Here is a link to an ESR meter that I designed.https://www.eevblog.com/forum/projects/5-transistor-esr-meter-design/msg172136/#msg172136This is also an analog meter.Jay_Diddy_B

author: Tita
author_rank: Contributor
timestamp: June 19, 2013, 05:21:18 pm
content: I will try!But my panel meter is having the sensitivity around 350uA..will work?

author: PaulAm
author_rank: Frequent Contributor
timestamp: June 19, 2013, 06:05:49 pm
content: I made one of those; it's been pretty handy.I added a LED so I could remember when the power was on and put the whole thing in a box with space for the leads.Had to buy a Chinese meter off of ebay, but everything else was out of the junkbox.

author: firewalker
author_rank: Super Contributor
timestamp: June 19, 2013, 06:12:20 pm
content: This is mine.http://alexkaltsas.files.wordpress.com/2012/04/dsc00737.jpghttp://alexkaltsas.files.wordpress.com/2012/04/dsc00738.jpgAlexander.

author: Balaur
author_rank: Unknown
timestamp: June 19, 2013, 09:19:29 pm
content: Quote from: firewalker on June 19, 2013, 06:12:20 pmGeia sou,Great minds think alike:

author: firewalker
author_rank: Super Contributor
timestamp: June 19, 2013, 09:26:12 pm
content: Quote from: Balaur on June 19, 2013, 09:19:29 pmAlexander.
Homemade Landline phone intercom system - Page 1
Forum section: electronics / projects

author: Silex93
author_rank: Newbie
timestamp: February 28, 2015, 01:07:07 pm
content: Good day communityI am doing a project which requires me to connect two landline phones together and use them to form an intercom system. Currently the design i ma using can be found here.http://wandel.ca/homepage/phone-intercom.htmlI have successfully created this circuit (except i used those small 12V piezoelectric buzzers instead of the sonalerts) but what i am seeking to do now is not using the buzzers anymore (kinda annoying sound) but to use the actual ringing mechanism within the phone.I have been doing some reading around about how much volts it takes to ring a landline phone and i think it's about 48-70vAC at around 20hz?But from the circuit i currently have, i am not sure how to implement a similar mechanism whereby if one phone is picked up, the other one is rung and vice-versa. Any help is greatly appreciated

author: German_EE
author_rank: Super Contributor
timestamp: February 28, 2015, 05:16:10 pm
content: A phone will only ring if the handset is down (the technical term for this is 'on hook'). So, have a button on each phone that places 90V @ 20 Hz on the line and the internal circuit of the phone will do the rest with the ring tone being heard in the earpiece of the calling phone.
Homemade PCB Exposure Units - Page 1
Forum section: electronics / projects

author: beanflying
author_rank: Super Contributor
timestamp: April 11, 2018, 09:41:33 am
content: Interesting getting back into making PCB's after a long long time away (I tend to use protoboard for one offs and have used online).I started with Dalo Pens and a Fishbowl way back when but have decided to arrange a UV development set of bits. The idea isn't really new and there is a few YouTube videos on similar units including some home built chassis's by people with far to much time on their hands.So I started with an Epson Scanner from the local op shop for $10 and ordered 5m of 3528 U/V Led strip off evilbay.While waiting for the tape to arrive I started stripping out the Scanner of the non useful stuff but left the switchpad installed minus some of the extra components to drive a little Ardiuno (code to be tweaked) and added a four digit LED and a couple of tactile switches for +- of power and time.The stock buttons were sanded back and given a coat of silver for fitting some new labels. Still have a small matching light pipe to add under the display.

author: beanflying
author_rank: Super Contributor
timestamp: April 11, 2018, 09:54:09 am
content: The U/V Strip arrived today obviously made from floor scrappings as it had nearly 20 joins in the 5MAnyway I unrolled it trimmed it to 250mm lengths and squashed it under a few bits of glass on top of my coffee machine to straighten out (about 60 degrees)Spacing I wasn't to worried about but I decided to use most of the roll which gave me 19 strips due to being sent 4.9mand 20 gaps on the non conductive foil cardboard. 6mm Nuts worked well for 10mm spacers with an occasional check with a ruler.For wiring I ran positive one side and negative the other and supplied in the middle by some 16AWG wire as the power draw is nearly 2A. Wire links were bent around a carpenters pencil to loop around the oposite polarity pads.Power to burn at 100%, final wiring and programming to be done over the next few days.Tracing potential too. This is an inkjet print under a sheet of standard paper.

author: beanflying
author_rank: Super Contributor
timestamp: April 13, 2018, 06:24:22 am
content: Not sure if it entirely needed based on some online videos but I made a Amber lamp of about 1W. 10 strings of 5 with a 100 ohm dropper on 12v gives plenty of light to work by. Clips onto the shelf above the workbench when needed.

author: beanflying
author_rank: Super Contributor
timestamp: April 16, 2018, 04:11:16 am
content: Just some programming to go. Changed the plan a little to use a Pro-Micro clone with built in USB and installed it on a hacked replacement lower board for power and usb in so programming can be done covers on. Also ran plugs to all boards for ease of assembly.I used a cheapy evilbay fet board as I had a couple of spares along with a salvaged heatsink (not really needed)The Lightpipe on the LED board works better than the stock EPSON one.Back in a few days when I get some working code.

author: kripton2035
author_rank: Super Contributor
timestamp: April 16, 2018, 06:01:11 am
content: nice project ! subscribed .
Homemade plc working  - Page 1
Forum section: electronics / projects

author: little_carlos
author_rank: Regular Contributor
timestamp: August 17, 2015, 12:56:15 pm
content: hello guys, ive finally made a plc with a pic16f628a, il put the video here so you can see it working

author: rvalente
author_rank: Frequent Contributor
timestamp: August 19, 2015, 12:55:45 am
content: Nice, are you learning to program? F628 is a starting micro for many people, was mine as well!

author: little_carlos
author_rank: Regular Contributor
timestamp: August 19, 2015, 03:00:25 am
content: Quote from: rvalente on August 19, 2015, 12:55:45 ami use a program called ld micro, in this software you do the program in ladder(used in a real plc) for some variety of pics, very useful to short the time to make a program or to simulate or do your own plc like i did, im also learning c and little bit assembler haha
Homemade ProbeMaster SMD test probes - Page 1
Forum section: electronics / projects

author: wwjd1924
author_rank: Contributor
timestamp: February 23, 2022, 02:13:28 pm
content: This post is a double post due to browser trouble.Here's the other one:https://www.eevblog.com/forum/projects/probe-master-smd-test-probes-diy/

author: cdev
author_rank: Super Contributor
timestamp: February 23, 2022, 02:30:29 pm
content: Pogo Pins!Quite a markup they are getting on them. Those are spring loaded gold plated pins sold for test applications. They are mass produced so quite affordable in quantity. They are very good probes.They are used in fixedbed-of-nailstest jigs.

author: wwjd1924
author_rank: Contributor
timestamp: February 23, 2022, 03:27:07 pm
content: NOTE: this post should have been deleted!I made another one as my browser was giving trouble. sorry about that
Homemade Z80 powered 8 bit computer question - Page 1
Forum section: electronics / projects

author: sahko123
author_rank: Frequent Contributor
timestamp: April 17, 2017, 08:41:18 pm
content: Thanks for taking the time read this topic.I'm in the process of designing a simple 8 bit computer and I'm looking for a readily available 8 bit binary to hexadecimal decoder with 2 seven segment display outputs. Or alternatively a readily available 4 bit to hexadecimal converter with 1 seven segment display output. Its use will be to monitor the data and address bus of the 8 bit computer. I'm not intending to add an external crt/lcd monitor for the time being.Thanks for any relevant response.For whom it may concern the computer runs off of a z80 processor.

author: Kilrah
author_rank: Unknown
timestamp: April 17, 2017, 08:44:41 pm
content: https://www.eevblog.com/forum/beginners/7-segment-display-driver-for-hexadecimal/

author: starblue
author_rank: Newbie
timestamp: April 18, 2017, 08:18:56 pm
content: I built such a thing some years ago, using an ATMEGA48.

author: james_s
author_rank: Super Contributor
timestamp: April 19, 2017, 11:32:47 pm
content: Binary to hex is relatively easy, look at the internal schematic for a 7447 and you'll see how a decoder works, adding a few gates to decode the full set of hex values is pretty easy. Personally I would use a CPLD like the XC9536, it's cheap, small, and can drive the LEDs directly. You could even include multiplexing logic if you wanted to save some wiring.One issue that will remain is hex characters look pretty crappy on 7-segment displays, but if you use the CPLD it's trivial to use 14 segment displays instead.
Honey, where'd you put my PC ? - Page 1
Forum section: electronics / projects

author: digsys
author_rank: Unknown
timestamp: January 09, 2013, 03:09:23 am
content: Now I'm going to need glasses to FIND my PC !!www.solid-run.com/cuboxI do like the open source aspect.

author: SLJ
author_rank: Frequent Contributor
timestamp: January 09, 2013, 03:29:48 am
content: Actually, I like this PC for 25 bucks also. SD card drive, Linux, HDMI out, USB, LAN, Audio, etc. Might be similar to the guts in the first one.http://www.raspberrypi.org/faqs
Hook Up Wire Voltage Rating for Connecting DC Links of VFDs - Page 1
Forum section: electronics / projects

author: magicsmoke
author_rank: Regular Contributor
timestamp: July 08, 2019, 07:05:36 pm
content: I have always assumed that the hook up wire voltage rating is for Vac rms. For high voltage DC applications does the same voltage rating apply? I need to connect the DC links of three VFDs or AC Drives at nominally 710 Vdc. Would the correct standard voltage rating for the hook up wire be 1000 V (or can I use 600 V rated wire which is more widely available)? The drives are in a pretty cool environment, not subject to UV or chemical exposure, and run for only a very limited period of time.Any recommendations for sources?

author: floobydust
author_rank: Super Contributor
timestamp: July 08, 2019, 07:17:24 pm
content: UL 1015 wire is rated 600VRMS or 750VDC. Assuming the wire pulls do not nick the insulation, you need a decent electrician because arc-flash would be catastrophic.The wire voltage ratings are the voltage (electrical) "class" so 600V could be 625V and still OK.

author: langwadt
author_rank: Super Contributor
timestamp: July 08, 2019, 07:33:06 pm
content: Quote from: magicsmoke on July 08, 2019, 07:05:36 pmthis has some,https://www.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/238000/FA238474/en_US/LXM32_DC_bus_Manual_V101_EN.pdf

author: ConKbot
author_rank: Super Contributor
timestamp: July 08, 2019, 08:45:46 pm
content: I've used MTW (machine tool wire) VW-1 that was 600V rated, that had a secondary 1KV UL type 1032 rating (not sure which type rating you'd need for your application), I got it purely for flexibility at relatively low cost. It was nice and flexible, and had a dual layer insulation (white inner, black outer) made for being able to see nicks easily.
Horizontal Tilt Switch Dual Ball vs Single Ball, SW-200D vs SW-200  - Page 1
Forum section: electronics / projects

author: sleemanj
author_rank: Super Contributor
timestamp: February 28, 2020, 11:24:06 am
content: Does anybody have any knowledge they can impart on the difference between the commonly available (from Ali etc) SW-200D and SW-200 horizontal ball tilt switches?From what I gather the 200D is dual ball and the 200 single ball, but I can't see much of a difference in "performance" between them.I actually have both on my bench here and the most I can say is that the 200D is noisier, has a higher or less stable resistance. The 200D is at least from the vendor I used a little more expensive.
Horse paddock maintenance using robotics - Page 1
Forum section: electronics / projects

author: Jameslpom
author_rank: Newbie
timestamp: July 29, 2018, 04:33:45 am
content: Hi there,I am new to electronics as I didn't have a project to drive forward but now I do.I have 20 acres of grazing land with 15 horses, I don't have the space, funds or time to purchase a tractor for pasture management.I suppose the reason why I am writing on this forum is that I want to develop a machine or multiple machines that can do the following tasks. Aeriation of soil, scarification of soil, and weeding established weeds all with capabilities of rugged-ish terrain. The difficulty with this as always is budget so time and is the saviour. If it takes a long time that is fine, compensating with multiple machines would speed up work rate.I don't believe there are any products on the market to suit these requirements and they are real world problems for a mass of horse owners and small land owners.My questions to start with are:Does anyone know of something that can do the above jobs that is already existing?Can anyone help by discussing possibilities regarding electronics and engineering?It's a big ask but if you are interested let me know, I have lots more information on the desired actions and I would appreciate any support I could get.Kind regards.James.

author: tomato
author_rank: Regular Contributor
timestamp: July 29, 2018, 05:01:18 am
content: Quote from: Jameslpom on July 29, 2018, 04:33:45 amYou plan to develop a machine in less time and for less money than it takes to go out and buy a tractor? I'd say that's pretty optimistic.

author: sleemanj
author_rank: Super Contributor
timestamp: July 29, 2018, 05:23:58 am
content: Driverless tractor.https://en.wikipedia.org/wiki/Driverless_tractor

author: tautech
author_rank: Super Contributor
timestamp: July 29, 2018, 05:55:55 am
content: You're in the home of Landrovers so find a cheapy and tow a set of harrows then get a 12V spray pack to put in the back and with either a broadcast nozzle, boom or C-Dax unit then use selective sprays to manage the pasture weeds.An 8' set of harrows will be plenty for the Landy to pull but you could go to 10' at the risk of getting them through gateways and just physically handling them.Different styles of harrows that can be flipped will manage the manure or the pugging along with scarifying the topsoil surface to promote pasture rejuvenation and growth.Timing of when each operation is undertaken is crucial to good results and keeping cost down.

author: Dubbie
author_rank: Unknown
timestamp: July 29, 2018, 05:58:14 am
content: The electronics will be the least of your problems.

author: woodchips
author_rank: Frequent Contributor
timestamp: July 29, 2018, 01:17:09 pm
content: You are lucky you are in the UK.Buy an old Ransomes Commander 3250 mower, or other similar models, strip all the mowing stuff off and you have the world's greatest off road vehicle. With tractor tyres it will go anywhere. As a bonus you also have a pile of old reel cutters, hydraulics etc with the actual cutting pump rated at around 25kW you won't be short of power.Use mine in my wood, brilliant.
Host_client usb header load switching  - Page 1
Forum section: electronics / projects

author: Md Mubdiul Hasan
author_rank: Regular Contributor
timestamp: November 27, 2017, 06:44:49 am
content: Hello everyone,Kindly help me in the following circuit to understand the action,This is a header circuit to make a bridge between device and host.Lets say Magconn connector(https://www.hackster.io/OscarSeo/getting-started-with-magconn-6ecbd3) is Device-A and CN1 is Device-B.When the 2 devices are connected, VBUS would be same on both side ( no matter VUSB is comming from device -B).At this time ID signal from device-A will be floating in host mode. Not sure ID signal from CN1 will be floating or grounded!Question arises in my mind,1. CN1 connector is a micro usb male, which connect my device to the one side of header.2. Transistor Q3 is being biased from +usb 5V, is responsible to turn Q1 OFF in case on input overvoltage?3. Not sure why extra 1-7 wire is connected afetr Q1, then U1 active high IC is powered by VBUS ?4. Not sure how the M_SIG signal is used here, the magconn connector connect with just a magconn header with host. Kindly explain it in detail.5. By the U3 IC, how the active load is acting ?(NO datasheet found)6. If the host is not connected I think VBUS will be not available in P+ test point, right?7. Do you think, D+,D-,ID signals can be show in scope, if both device are connected?Help me please.
Hot air gun / ceramic heating with 12v DC - Page 1
Forum section: electronics / projects

author: lukasz.kostka
author_rank: Contributor
timestamp: December 12, 2018, 07:03:21 pm
content: Hi.I was wondering if using 12v DC is ok instead of AC voltage for heating elements in hot air gun and ceramic heating element inside a soldering iron. I plan to put both my soldering iron and hot air gun inside one enclosure. I have:Zhaoxin 858D (clone of atten 858D)Solomon SL-20 CMC soldering iron

author: helius
author_rank: Super Contributor
timestamp: December 12, 2018, 07:12:13 pm
content: 12V is barely enough when you take conductor size into account. The TS100 iron operates from 12VDC but only supply 30W of heat or thereabouts at that voltage.The reason most tools use AC is it is easier to control power delivery using synchronous switching (zero voltage switching).

author: lukasz.kostka
author_rank: Contributor
timestamp: December 12, 2018, 07:16:44 pm
content: So 12v DC will require more amps and thus thicker cables. Good quality x8 wires silicone cables are really expensive. I could use 2x 10 AWG for heating elements ans much thinner cables for else. Sounds reasonable ? Cables that came with soldering iron and hot air gun are really stiff. I'd really like to swap them for silicone wires.

author: 001
author_rank: Super Contributor
timestamp: December 12, 2018, 07:37:20 pm
content: Quote from: lukasz.kostka on December 12, 2018, 07:16:44 pmNothing goodAC phase regulator is simplest and powerfull way

author: GeoffreyF
author_rank: Regular Contributor
timestamp: December 12, 2018, 07:42:28 pm
content: The lower voltage, the higher the current to achieve the same wattage (heating effect). The higher the current, the thicker the wires needed to deliver it.

author: wraper
author_rank: Unknown
timestamp: December 12, 2018, 08:06:37 pm
content: Hot air heating element is powered directly from mains voltage and control circuit won't work from DC without modification. Solomon is powered from 24V AC and heater control circuit won't work from DC. What you are trying to do is just stupid BTW, it's way better to have those separate.

author: wraper
author_rank: Unknown
timestamp: December 12, 2018, 08:09:17 pm
content: Quote from: lukasz.kostka on December 12, 2018, 07:16:44 pmIt would just result in lower current. 4 times less power from 24V heater.

author: lukasz.kostka
author_rank: Contributor
timestamp: December 12, 2018, 08:14:38 pm
content: QuoteWhat will result in lower current ? 12V DC, 24V AC ?QuoteLess power than from 12V DC ?2A @ 12V = 24W1A @ 24V = 24W

author: wraper
author_rank: Unknown
timestamp: December 12, 2018, 08:40:04 pm
content: Quote from: lukasz.kostka on December 12, 2018, 08:14:38 pm24@ 24V = 1A -> 24W24@ 12V = 0.5A -> 6W
Hot swap controller audible noise - Page 1
Forum section: electronics / projects

author: caffeinatedbard
author_rank: Regular Contributor
timestamp: December 05, 2013, 04:09:43 pm
content: Hi ,I have a simple hotswap controller circuit with a high side fet and a common mode choke in series with the load and a 100uF capacitor in parallel with the load.During testing, trying to test overcurrent with the circuit on sometimes I hear an audible buzzing sound when I short the + and - terminal. Do you think that would be coming from the FET or from the common choke?Any suggestions are appreciated.-bard

author: ConKbot
author_rank: Super Contributor
timestamp: December 05, 2013, 04:26:27 pm
content: What is the hot-swap controller? If It might be retrying every few (hundred?) ms, making a nice pulsed waveform. I'd expect the noise to be coming from the choke, and not the fet.

author: nctnico
author_rank: Super Contributor
timestamp: December 05, 2013, 06:03:07 pm
content: FETs (and transistors in general) can make noise.

author: envisionelec
author_rank: Frequent Contributor
timestamp: December 05, 2013, 07:26:22 pm
content: Quote from: nctnico on December 05, 2013, 06:03:07 pmReally? Wouldn't they disintegrate quickly? I've only known chokes and capacitors to make noise...

author: caffeinatedbard
author_rank: Regular Contributor
timestamp: December 05, 2013, 10:04:25 pm
content: The hot swap controller is the LTC4215.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: December 06, 2013, 12:30:19 am
content: Put a dab of epoxy on your choke, if it isn't enclosed. That will dampen the vibration.

author: nctnico
author_rank: Super Contributor
timestamp: December 06, 2013, 01:16:25 am
content: Quote from: envisionelec on December 05, 2013, 07:26:22 pmJust run enough current through them. Its not harmful BTW.
Hotair station microcontroller not controlling ??? - Page 1
Forum section: electronics / projects

author: MathWizard
author_rank: Super Contributor
timestamp: October 17, 2021, 09:10:47 am
content: I have a 858D clone hotair station that stopped working. It seems all the external circuits are working, but it won't enable the fan, or turn on the BJT to turn on the AC-opto-coupler. Both BJTs checkout fine. The display lights up and I can move the temp setting up/down like normal, and I can see the MCU talk to the ram chip when you push the button.But it won't turn on the fan or heater. The LM358 temp circuit seems about as expected, but I don't know if P0.1 is doing what it should be.hotair stationhttps://blog.enbewe.de/posts/images/858D/858D_Schematic-big.pngS3F94C4https://ixapps.ixys.com/DataSheet/PS0315.pdfI see it has SDA and SCK, there's also a reset pin I wired a 10k onto, but never tried yet. Is there any way to "ask" the MCU if it's ok ? Those pins are in use by the circuit, I'd probably have to pull it, but then what, I have a Buspirate but I don't know programing so I don't know what to do.I meant to put this under repair

author: MathWizard
author_rank: Super Contributor
timestamp: October 21, 2021, 11:11:52 am
content: Hmm I thought maybe the temp sensor burned out, it seems it's a PTC at 1.5R at room-temp. Then I thought maybe the schematic was labeled wrong, but no I had the 3pin connectors for the fan VR swapped with the PTC sensor. That makes sense in the op-amp circuit with the MCU setting P0.1I think I the triac burned out ages ago, because I definitely remember it working, then stopping working in the middle of something. Then ages later I replaced it, and a filter cap too close to it's voltage rating. But I mixed up the connectors, and forgot all about it.
hotplate/heater - Page 1
Forum section: electronics / projects

author: ShadyK
author_rank: Contributor
timestamp: April 06, 2014, 08:17:38 pm
content: Hello. My current fortay is mobile phone repairmainly by hobbie..if any 1 else here does the same you will no that iphone screens are bonded together with UV glue.. now there is a peice of kit out there called a seperation tool. This i think in theory is a hot plate with 4 clamps.. has any 1 ever built or could any 1 build or design something like this as they are 150gbr to buy new? And for such a simple device seems steep
How 2-pin AC phone charger drain ESD charge to Earth/Ground?  - Page 1
Forum section: electronics / projects

author: Wilson__
author_rank: Frequent Contributor
timestamp: November 26, 2024, 10:21:07 am
content: Human walking on carpret can generate up to 30 to 50 kV.Phone USB pins are 2mm from touch of human finger.6 kilo voltage can fly across and the phone is electrostaticly charged.How the charge discharge back to Earth for double insulation cellular phone chargers that use 2 pin AC plug?https://www.sciencing.com/calculate-voltage-spark-gaps-8776030/

author: Zipdox
author_rank: Regular Contributor
timestamp: November 26, 2024, 11:59:58 am
content: They usually have class Y safety capacitors between the input and output. I assume they absorb a significant amount of the charge. Someone correct me if I'm wrong.

author: Ian.M
author_rank: Super Contributor
timestamp: November 26, 2024, 12:22:50 pm
content: I've just checked a typical small SMPS board I had lying about and the Y capacitor (between output 0V and the negative of the primary side DC bus) is 2.2nF. TheHBMequivalent capacitance for ESD testing is 100pF. Real life capacitance of your body to ground may well be lower - it depends on geometry (i.e. proximity of nearby objects at ground potential), thickness and material of your shoe soles thickness and type of flooring, etc.Assuming 100pF and direct contact with the plug shell and thus secondary side 0V, the charge will equalise with the Y capacitor, reducing the voltage by a factor of over 20, reducing a 50 kV HBM charge to under 2.5 kV, which for better quality SMPSes is within their insulation withstand ratings. The charge then slowly leaks away to the primary side via PCB surface leakage etc.Of course if the charger is a 'CE - China Export' low grade piece of cr@p, it may not even have a proper Y capacitor and there is a high risk of a 50 kV HBM ESD event causing insulation breakdown leaving its output a mains live shock hazard!

author: PGPG
author_rank: Frequent Contributor
timestamp: November 26, 2024, 12:42:50 pm
content: Quote from: Ian.M on November 26, 2024, 12:22:50 pmIt happened me not long ago that I connected one such charger to charge small headlamp and accidentally that headlamp just touched the Protective Earth socket pin. Nothing should happen, I think, but it ended with sparks, stench and smoke and both devices being damaged.

author: Ian.M
author_rank: Super Contributor
timestamp: November 26, 2024, 12:59:37 pm
content: You were lucky - the fake 'CE' charger is better dead, and the headlamp is an acceptable casualty vs it killing *YOU*!DiodeGoneWild frequently does full teardowns of dodgy USB chargers, often including stripping down the switching transformer and commenting on the insulation and creepage distances.https://www.youtube.com/playlist?list=PLfUGOPyKWwiriWhjmdtvjBw_J7X_X5OnU
How a voltage sensing circuit works - Page 1
Forum section: electronics / projects

author: ploutone
author_rank: Newbie
timestamp: June 05, 2017, 09:54:27 am
content: Hello;In a project I am working on (totem pole PFC), I need to sense the input AC voltage and for that I am thinking of using LEM LV 25-P, but I can't figure out how the circuit exacly works ( especially the highlighted red part of the circuit ) and how is the ratio equals to 2.5*RM/(R1+R2)Thank you very much.

author: Phoenix
author_rank: Frequent Contributor
timestamp: June 05, 2017, 10:25:42 am
content: The module is a really a current -> current converter. You use resistors to convert from voltage to current and back to voltage.The actual internals are a feedback compensated hall effect sensor. It detects the magnetic field in the transformer and injects an opposite current into the secondary with the aim of zero flux in the transformer. It's kind of like a current transformer, but able to operate at DC current too.E.g. if you inject 10mA into the primary, it will output 25mA on the secondary.

author: tatus1969
author_rank: Super Contributor
timestamp: June 05, 2017, 10:34:06 am
content: googling for "closed loop hall current transducer" leads you tohttp://www.lem.com/hq/en/content/view/168/155/,among others.For your application, the datasheet figures are more important. Can you live with 0.9% accuracy, 2.5kV isolation, 40µs step response (corresponding to roughly 9kHz bandwidth)? If yes, then for every mA you feed in, it produces 2.5mA at its output. Use resistors at input and output to convert voltage to current and vice versa.
How are light pipes mounted to board? - Page 1
Forum section: electronics / projects

author: strobot
author_rank: Contributor
timestamp: June 30, 2013, 06:39:38 pm
content: How are light pipes such as these mounted? Adhesive? Captured by the geometry of the PCB mounting holes and front panel hole?http://www.bivar.com/Images/Cart/SLP3-150-XXX-X.pdf

author: free_electron
author_rank: Super Contributor
timestamp: June 30, 2013, 07:16:12 pm
content: Hole geometry. The light pipe has bifurcated pins that snap in

author: strobot
author_rank: Contributor
timestamp: June 30, 2013, 07:38:53 pm
content: Ah, you're right. I see it now:The mounting holes are supposed to be dimensioned 0.046" nom. , and the width of the bifurcated mounting posts is 0.050" to allow a press-fit.
How are small-signal linear MOSFET amplifiers designed? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: April 29, 2018, 07:42:22 pm
content: How are small-signal linear MOSFET amplifiers designed?Eg, Source follower, common source. We no longer have the Vbe approxiamtion, and device parameters vary quite widely.For a bipolar, we can assume (say) a gain of at least 100, and Vbe ~= 0.65, and get some way using basically just that. I'm ignoring Early effect, tempcos - but at least you can have a stab at it.Now, say I have a say a TSM2302, (Farnell 2628137), how do I design(1) A source follower(2) A gain of 10 amplifier using that?I'm guessing I have to start by assuming a minimun transconductance, but how about biasing etc?

author: EmmanuelFaure
author_rank: Regular Contributor
timestamp: April 29, 2018, 08:19:48 pm
content: http://www.mhhe.com/engcs/electrical/neamen01/ch06.pdf

author: Wimberleytech
author_rank: Super Contributor
timestamp: April 30, 2018, 03:17:57 am
content: I am scratching my head as to "why?"A source follower would be straightforward. The input could be easily biased to guarantee operation over the variation of VT and transconductance.

author: 741
author_rank: Frequent Contributor
timestamp: May 01, 2018, 09:00:25 am
content: Thank you Emmanuel, that looks ideal.
[Solved] How Are The "Voltage Levels" Achieved By A Stepper Motor Driver? - Page 1
Forum section: electronics / projects

author: Darkwing
author_rank: Contributor
timestamp: January 16, 2019, 11:27:05 pm
content: Hi folks!I'm currently diving a little bit deeper into stepper motors and controllers and drivers; I readthis blog postand saw this video:and in it there was this graph displayed on a scope:It kind of "shows the output of the stepper driver DRV8811 to a coil producing the microsteps." The graph is used to display different decay modes, but this doesn't matter.I'm not exactly sure what I see here. Can you please help:I understand the "small ripples", this is the current chopping from the driver. But it seems, that this current chopping is always happening on a "base plateau voltage", forming the "big stairs" resulting in this near sine wave shape. Because current follows voltage, you can only "current chop" if you "voltage chop" with some sort of PWM'ed signal. PWM always goes rectangular from 0V to HIGH (or the signal level of your choice). But here, it seems to exist some sort of sine wave generation. A modified sine wave of voltage levels. I looked into the datasheet but found no hint of such a part ...(http://www.ti.com/lit/ds/symlink/drv8811.pdf)If it is an oscilloscope it can only measure voltage over time (directly). It can't measure current. So is this graph maybe a calculation from the scope, a resulting graph from other inputs? Hence the unit label "500mA Ω" ...? What was done to achieve this calculated graph in the scope then?These are my thoughts ...I actually don't really know how to put my question.Can anyone understand and knows what I need to know?There must be a darn easy explanation ...Thanks!Darkwing

author: mvs
author_rank: Frequent Contributor
timestamp: January 17, 2019, 08:50:45 am
content: Quote from: Darkwing on January 16, 2019, 11:27:05 pmCurrent can be measured indirectly by using current probe or external shunt. DSOs have usually settings for unit and unit/V ratio of probes to display units and values correctly. DSOs in middle and higher price range may also have data interface to probe and can change this settings automatically.

author: Darkwing
author_rank: Contributor
timestamp: January 17, 2019, 03:37:53 pm
content: This must be it, yes. It is the measurement of a clamp-on current probe, that is available for oscilloscopes. This explains everything.I noticed (googled) that in the past some guys where asking kind of the same question like above – with no satisfying answer. So I reframed the question to: "how to measure the coil current of a stepper motor", finally resulting in: "how to measure current with an oscilloscope" in general.This lead me to current probes (expensive), shunt resistors (cheap) and the concept of DIY current probes using a small toroid core with a few turns of wire (clever). Found thisforum post here,very helpful.Well, anyway, thanks!Solved, I guess.
How are these pins soldered in the proces ? - Page 1
Forum section: electronics / projects

author: Kjelt
author_rank: Super Contributor
timestamp: June 22, 2017, 07:02:57 pm
content: I was looking at my ST Nucleo boards and they have these gold male headers with long pins (almost half of old wirewrap size).The components and the pins look like they are soldered with a reflow process.But how? I mean they can not put the paste first then press the pins in or the paste would be on the pins but they are perfectly clean.Putting paste on each pin after the pins are placed would be tremendously difficult, perhaps a 3D robotsyringe hand but I am puzzled.So who knows how this is done, it is not wave soldered that I am sure.

author: helius
author_rank: Super Contributor
timestamp: June 22, 2017, 07:15:09 pm
content: Sometimes assemblies like these use selective soldering with a solder fountain. It can do the thru-hole parts without disturbing SMD components a few mm away.

author: Ian.M
author_rank: Super Contributor
timestamp: June 22, 2017, 07:21:51 pm
content: It could also be done with solder preforms. Seehttp://www.onboard-technology.com/pdf_febbraio2005/020510.pdf
How are they normalizing a frequency of this transfer function ? - Page 1
Forum section: electronics / projects

author: MathWizard
author_rank: Super Contributor
timestamp: July 20, 2023, 03:58:19 pm
content: In this transfer function example, H(s)=110s/(s^2+110s+1000) = 0.11s/((1+s/10)*(1+s/100))once they have it in standard form, with a pole at 10 and 100, they normalized the 1st pole, to be 1, and the 2nd pole became 10. I don't see how the how they get the 0.011 as the new K0.011s/((1+s/1)*(1+s/10))I tried letting new p1=(p1/p1)=1 and new p2=(p2/p1)=10, but then new k would still be 110/(1*10*10*10)=0.11 not 0.011And just switching to jw and letting new w=p1=10, well that doesn't get the 0.011 either.from page 11https://www.mcmsnj.net/cms/lib07/NJ01911694/Centricity/Domain/134/ENZ%20-%20Transfer%20Functions%20and%20Bode%20Plots.pdf

author: moffy
author_rank: Super Contributor
timestamp: July 20, 2023, 11:59:37 pm
content: To shift the frequency but maintain the same shape, the 's' terms all need to be multiplied by the same factor, which in this case is 10. So the upper term becomes 1.1 not 0.011 as they stated. Just to check I ran a quick test in LTSpice which I have included.

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: July 21, 2023, 05:21:13 am
content: Quote from: moffy on July 20, 2023, 11:59:37 pmAgree that this coefficient equals 1.1. Just substitute 10s for s in the transfer function, top and bottom.

author: MathWizard
author_rank: Super Contributor
timestamp: July 21, 2023, 09:34:45 am
content: Ok thanks, they used the same circuit in most that pdf but always had the 0.011. I didn't know ltspice does Laplace transforms like that, I'll have to try it. I'm just learning how to plot the complex poles/zero's of transfer functions. I have GNU octave, it looks pretty easy to plot them in that too.I'm making a modified copy of a Heathkit Curve tracer, and in the simulations, there's a lot of nasty over/undershoot mainly from the step generator, that makes it's way into the other opamp circuits. So I want to actually calculate my way to a better looking circuit, and model.

author: bson
author_rank: Unknown
timestamp: July 23, 2023, 09:36:32 pm
content: 0.11 is the sole zero, when it's scaled by 10 it becomes 0.011.Poles and zeros are in the same plane, so when scaling the plane they all change.
How avoid the response of a PIN photodiode for sunlight? - Page 1
Forum section: electronics / projects

author: Dhanushka
author_rank: Regular Contributor
timestamp: June 30, 2021, 04:08:33 pm
content: Hi,Currently, I am working on a project, a flame is needed to be identified some considerable distance(at least 10 m). I used a cheap general PIN photodiode and current to voltage converter referring a Texas instruments application note.Datasheet for a similar photodiode:https://www.vishay.com/docs/81503/bpv10nf.pdfBut this is not I used, I assumed that, that has similar character.Texas instruments application note for current to voltage converter:https://www.ti.com/lit/ug/tidu535/tidu535.pdf?ts=1625066511744&ref_url=https%253A%252F%252Fwww.google.com%252FI build this circuit on a piece of perfboard raising the photodiode cathode and inverting input of the opamp to prevent leakage currents. I used TL082 opamp instead the one used in AP note above because I only needed the DC response.According to the datasheet, the photodiode response only for about 950 nm wavelength. That is true when I tested at night this can identify a match fire well from about 1 m distance even the indoor lights are presents.But the problem is under the daylight the opamp saturates without a fire. Then I raised the supply voltage up to 12 V, down the feedback resistor to about 15 kohms and tested again that little bit works. But due to bright sunlight that sometimes goes high voltages.According to the Vishay datasheet, the reverse current of the photodiode rise only if the IR radiation is more than 1 mW/cm^2 for about 950 nm. As I know the solar has 950 nm IR radiation of 0.1 mW/cm^2. So, this should not be response for sunlight. But I am in a tropical country, the radiation may differ.But I know the suitable sensor is pyroelectric flame sensor. They are too much costly. That's why I use these ones.So, my problems are,1. May this a fake PIN photodiode?2. Is this sensor response other radiations like UV?3. Is there a way to prevent this sunlight IR radiation? (using a filter without disturbing fire response)4. Should I use a pattern recognition thing with AC response to detect a fire?Thanks.