hybridfree/eevblog-posts huggingface dataset:
Create a Design Spark Mechanical Project and pit your invention against the best - Page 1
Forum section: electronics / projects

author: DesignSparkMechanical
author_rank: Newbie
timestamp: November 15, 2013, 08:11:28 pm
content: RS Components is searching for talented engineers to pit their ideas against each other to unleash their gift of invention. With a £10,000 worth of cash prizes plus a Rep Rap Pro 3D Printer up for grabs, truly creative engineers have it all to gain! There is a brief you need to meet for your design, but if you have a idea you think could change the world now is the time to see others agree with you?The aim of the challenge is to urge all engineers to road test DesignSpark Mechanical and take bring those life changine 2D sketches into printable prototypes The most popular design, as voted for by the DesignSpark engineering community, will be transformed into a physical prototype using a 3D printer, and presented to the winning engineer along with the top prize of £5,000. Two runners-up will each receive a prize of £2,500.To take part in the challenge, participants need to simply download the free DesignSpark Mechanical software fromwww.designspark.com/mechanical, create a 3D representation of their design, and submit the final idea by uploading it to DesignShare, the collaborative project space on DesignSpark.com, where each idea will be posted and votes will be cast. All entries must be received by 17:00 GMT on November 22, 2013. To enter simply click herehttp://bit.ly/1b2tb9O

author: Rufus
author_rank: Super Contributor
timestamp: November 15, 2013, 08:17:35 pm
content: From the entry pageQuoteSo restricted to you must help the disadvantaged or save the planet politically correct bullshit. Makes me want to puke.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 16, 2013, 08:21:28 am
content: spamming sections is not cool either. anyway, downloading DesingSpark Mechanical now, see what it can do.
create spice model for rf filter - Page 1
Forum section: electronics / projects

author: electronx
author_rank: Regular Contributor
timestamp: October 24, 2024, 10:11:06 am
content: I searched for a spice model for LFL182G45TC1A108 but couldn't find one. I want to create a two-terminal filter model by taking a plot from the graphic. Is this possible in the pSPICE model editor?I extract data points

author: iMo
author_rank: Super Contributor
timestamp: October 24, 2024, 10:52:59 am
content: I would play with a design tool - see for example below.Like elliptic 3 or 5 or higher order would fit it aproximately, imho.The sim will not show exactly your graph, however.

author: electronx
author_rank: Regular Contributor
timestamp: October 24, 2024, 10:58:19 am
content: I think we can model the output/input ratio as a two terminal black box with datapoints that are frequency dependent in terms of power. Also, it wouldn't be bad to make an RLC passive filter out of this model. I'm sure someone here knows how to do that.

author: tggzzz
author_rank: Super Contributor
timestamp: October 24, 2024, 11:08:31 am
content: Spice works with ideal models of lumped components. At microwave frequencies those models are woefully inadequate.You can use RLC filter models as astartingpoint, realising the filter as interestingly shaped copper patterns. You will need either experimentation to get the exact dimensions, and/or use an EM field solver.
Create your own magnetic accelerator or coil gun! - Page 1
Forum section: electronics / projects

author: IVCoilgun
author_rank: Newbie
timestamp: June 13, 2014, 08:39:59 pm
content: Hey everyone, I'm Max, and I just wanted to let you guys know about this project that my friends and I are doing. We are optimizing coilguns (gauss guns) in an effort to make a guide to let anyone know how they can make one themselves! It's been an awesome project that's taught us a ton about electronics, especially since we started from minimal experience.Please check out our kickstarter campaign (http://kck.st/So3U5E) to get an idea of our progress and what we are trying to accomplish. You don't have to donate to get our info though, most of our findings will be published on our youtube channel, and we would love to discuss our ideas and progress with anyone!But of course, every little donation helps us fund our research. Thanks for looking!Also we would love to discuss design ideas with anyone interested, just reply here or shoot me a PM.

author: Dongulus
author_rank: Regular Contributor
timestamp: June 16, 2014, 10:30:31 pm
content: I thought this deserved a bump.I took a quick look around google for instructions on how to build coil guns. I only really found instructions for puny camera flash powered, single stage coil guns. The type of coil guns you guys want to build are on an entirely different level.From the looks of your Kickstarter page, you seem to have thought your project out well. The rewards seem quite reasonable, especially the PDF guide. I think $35 is a bargain when looking at potentially wasting much more time and cost of components by trying to figure out a design on one's own.I wish the best of luck for you guys.
Creating 0-50V analog output - Page 1
Forum section: electronics / projects

author: zephier
author_rank: Newbie
timestamp: February 11, 2016, 02:54:49 am
content: Hello all,I need to create a 0-50V analog DC output. The input signal that I am supplied with is a DC voltage that varies from 64-85V. Any ideas on how to create a 0-50Vdc output that is controllable from a microcontroller from this input voltage? The microcontroller that I am using is a C8051F340 (http://www.digikey.com/product-detail/en/C8051F340-GQ/336-1298-ND/990815?WT.srch=1). The load that the 0-50Vdc is going to draws a max of 30mA. Let me know if you guys have any ideas. Thanks!

author: mariush
author_rank: Super Contributor
timestamp: February 11, 2016, 04:49:29 am
content: Quickest that comes to my mind would be using a digital potentiometer in the feedback of a switching regulator likeLM5009, which can work directly with input voltages up to 95v.You're only going to get a minimum of 2.5v at the output without resorting to some tricks, and I'm not sure if the wiper pins of a digital potentiometer would like to see 50v or so on them, but like I said, it's the first thing that came to mind.You should check out how some linear adjustable power supplies are made, attached you have an example

author: mtdoc
author_rank: Super Contributor
timestamp: February 11, 2016, 05:01:54 am
content: Basic buck converter with MCU controlled PWM would work,no?Quick google search of "8051 controlled buck converter" givesthis

author: Someone
author_rank: Super Contributor
timestamp: February 11, 2016, 07:35:01 am
content: There are opamps from the major brands that will provide such an output directly, just be careful with the input common range limitations.

author: poorchava
author_rank: Super Contributor
timestamp: February 12, 2016, 10:00:10 am
content: How fast do you need to vary that voltage?Sent from my HTC One M8s using Tapatalk.
Creating 10.7 MHz from other frequencies  - Page 1
Forum section: electronics / projects

author: DMartens
author_rank: Contributor
timestamp: June 07, 2024, 08:56:14 am
content: Hi ... I need to create a 10.7 MHz frequency to use with a TMS9918 ... this 10.7 MHz is triple the NTSC color carrier frequency of 3.574595 MHz.I have crystals of 3.574595 MHz, also of 14.318180 MHz (4xNTSC) and also of 28.636360 MHz (8xNTSC).I know using a PLL-type circuit with an appropriate divider-factor in the feedback loop would be able to achieve this.Is there a way to generate 10.7 MHz from any of these above frequencies _without_ using a PLL?

author: moffy
author_rank: Super Contributor
timestamp: June 07, 2024, 09:50:32 am
content: Quote from: DMartens on June 07, 2024, 08:56:14 am100% multiply the 3.574... by the 14.318... and bandpass filter at 10.7, but why instead of a PLL, I have no idea.

author: CaptDon
author_rank: Super Contributor
timestamp: June 07, 2024, 12:49:03 pm
content: 10.7 and 21.4 crystals are cheap and easy to obtain. Why not just order one? How do you get 10.7 by 'multiplying' the 3.57 by the 14.318???

author: jzx
author_rank: Regular Contributor
timestamp: June 07, 2024, 12:53:41 pm
content: You can do a 3.57 MHz oscillator, filter the 3rd harmonic and amplify. Search "overtone" oscillator o "frequency multiplier"

author: David Hess
author_rank: Super Contributor
timestamp: June 07, 2024, 01:02:44 pm
content: Quote from: jzx on June 07, 2024, 12:53:41 pmThat is what I would do. A tripler stage is trivial; implement a class-c amplifier stage and used a tuned filter on the output to recover the third harmonic. A 3.57 MHz square wave from a fast logic gate could be used.

author: wraper
author_rank: Unknown
timestamp: June 07, 2024, 01:32:47 pm
content: You can make 3.57 MHz crystal run on 3rd overtone. Just why not buy a correct part?

author: mawyatt
author_rank: Super Contributor
timestamp: June 07, 2024, 01:34:45 pm
content: Could use the 3.57MHz crystal in an overdriven oscillator and then injection lock a 10.7MHz oscillator to the 3.57MHz crystal oscillator (3rd harmonic).Best,

author: PCB.Wiz
author_rank: Super Contributor
timestamp: June 08, 2024, 09:12:00 pm
content: Quote from: DMartens on June 07, 2024, 08:56:14 amSure :The modern way would be a Schmitt XOR gate, and simple third phase RC delays. Then (A XOR C) XOR B gives 3f ( eg using SN74HCS86)or, you can make a ringing circuit with an LC and moderate Q at 3f, with Schmitt follower, and kick it with a narrow impulse at f.These give 3.574595 *3 = 10.723785 MHz
Creating a "sync" pulse from a Video GenLock Signal. - Page 1
Forum section: electronics / projects

author: mrpackethead
author_rank: Super Contributor
timestamp: June 14, 2016, 04:28:17 am
content: Hi, i need a way to creating a short sync pulse out of a video genlock signal, so i can sync some other non video equiment up to video, so i dont' get weird strobing etc.Is there a simple chipset for doing this somewhere?

author: msraya
author_rank: Unknown
timestamp: June 14, 2016, 06:55:26 am
content: Lm1881?

author: rx8pilot
author_rank: Super Contributor
timestamp: June 14, 2016, 07:44:26 am
content: tri-level sync?Sent from my horrible mobile....
Creating a Line Follower Robot (ESP32 & QRE1113) - Page 1
Forum section: electronics / projects

author: Bob-Sto
author_rank: Newbie
timestamp: July 07, 2024, 02:33:43 pm
content: Hello everyone,I am embarking on a project to build a line-following robot from scratch, and I am currently working on the electronic schematic.My robot is equipped with 4 QRE1113GR sensors for line tracking and an OLED I2C display for information output. I have chosen an ESP32 as the microcontroller.Here is the schematic of the robot that I created using KiCad. I would greatly appreciate it if you could review it and let me know if there are any errors or possible improvements.Thank you very much for your help!
Creative Soundworks DTT2500 - wont power up - Page 1
Forum section: electronics / projects

author: mrmuzzio
author_rank: Contributor
timestamp: September 27, 2021, 02:54:29 pm
content: Hi !!! I have a "Creative Soundworks DTT2500 Dolby reciever" for quite some time... and a few days ago it powered off a few times...Today it didn't power on, not even a led. Reading this post:https://www.eevblog.com/forum/projects/revising-cambridge-soundworks-dtt2500-amplifier-adding-a-toslink/... gave some courage to dismantle the device, and I took a look inside.I've checked the power brick, the capacitors, de-soldered the shield and I couldn't find any sign of trouble.Messing around with my multimeter I've moved the fuse in the board, and it powered up !!!, when I removed the fuse I saw that the holder seems to have some rust... I've applied some contact cleaner and it's working again...Looking around I've also found this video on cleaning the volume pots...Hope this helps someone that may have the same problem ... and I'm praying that the fuse holder was the only problem....

author: mrmuzzio
author_rank: Contributor
timestamp: September 29, 2021, 11:53:57 am
content: Hi... bad news... the device turned off again and it won't power up....Looking closely I can see that the power led brights really dim, almost imperceptibly...I'l take it appart again to try to idenfity the problem.. Any help is really welcome.Thanks!!!
Creepage between relay contacts - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: October 06, 2018, 04:38:12 pm
content: I'm tweaking a board used in an industrial setting and I'm not sure how to interpret the creepage rules for relay contacts.I diverge slightly......Thinking about required creepage for a connector for example 120Vac MAINS supply to a board, only basic is required between the hot and neutral, no issue there.Now thinking about creepage requirementsbetweenthe contacts of a relay (not the contact to coil creepage). The relay is rated for 250/277Vac, the pin to pin contact spacing is 5mm, allowing creepage of about 2.75mm (> 100mils). This is obviously adequate from a functional perspective and even satisfies safety requirements for basic for pollution degree 2.Now if working to a pollution degree 3 standard, basic or functional creepage is 151mils/3.8mm, however the relay contacts are obviously expected to operate so do creepage requirements even need to be considered between relay contacts?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 06, 2018, 10:19:12 pm
content: Relays are usually sealed, so we don't expect contamination inside (unless it's not, in which case you better buy a fat one?).Can always rout between pins if you need more creepage. On the relay base itself, there probably aren't fins or slots to increase creepage distance, in which case either UL doesn't care(?!) or it would have to be potted under (probably with an approved inspection process). The good bet would then be finding a higher voltage/category part.Tim

author: Giaime
author_rank: Regular Contributor
timestamp: October 08, 2018, 02:29:06 pm
content: For this kind of stuff you need to take a look to the rated insulating voltage of the relay contacts, and make a comparison with what your standard requires.For example, you might need functional isolation for 230VAC, with an overvoltage category that requires testing at 2500VAC for 1 minute. If the relay is for example rated for 4000VAC for 1 minute, then you're fine.You need to search and understand the safety standard to correlate between the creepage/clearance tables and the "equivalent" test voltage.Usually safety standards let you choose between those options: either guarantee a measurable distance (such as creepage) or do an equivalent electrical test (for example 2500VAC for 1 minute).Some relay datasheet also say something like "creepage equivalent to 5mm according to IEC xxx standard" or similar.
Creepage/Clearance PCB-to-PCB and PCB-to-Housing - Page 1
Forum section: electronics / projects

author: eer
author_rank: Newbie
timestamp: August 10, 2020, 10:15:17 am
content: Hello,I've been a long time silent reader of the forum, but this is my first post.I'm dealing with the insulation coordination (clearance and creepage checks) for several AC-DC and DC-DC (~ 1kV DC) converters, each one of them consisting of several PCBs tightly fit in an enclosure.One of the main standars I have to comply with is the EN 60664.For the PCBs design I am working with Altium v20.My main question is the following: has anyone encountered anautomatedway of defining and performing clearance/creepage rules checks for tracks and padsacross PCBsor between a track/connector in a PCB and the housing connected to PE?I can define a set or rules for each PCB and this works fine for that PCB alone, but then for the physical aseembly process some violations of the minimum distances arise due to PCB-PCB or PCB-Housing interaction.Altium has introduced their Multi-Board projets which allow to perform 3D collision tests between PCBs, but no electrical rules checks so far.The possibility of exporting the .STEP file to a CAD software like solidworks and check the assembly there (insulation wise) is not conclusive.I wanted to know if anyone has encountered this issue and a potential solution,within Altium or outside it, I just want to hear your experience on the topic.Thanks in advanceCheers
Crimp plug compatble with Phoenix MTSB - Page 1
Forum section: electronics / projects

author: rcourtney
author_rank: Contributor
timestamp: April 16, 2020, 03:51:55 am
content: Does anyone know of a manufacturer that makes a crimp wire harness to the popular Phoenix Contact MTSB (1757022)?

author: Renate
author_rank: Super Contributor
timestamp: September 14, 2020, 03:05:33 pm
content: Bump.Oh, you've got me on a rant here.I hate that Phoenix little green crap.If I want a product with screw terminals, I'll put screw terminals on it.I won't put a connector that takes an adapter that has screw terminals.You end up with a plug with no cable restraint.I was looking for a plug equivalent to the two terminal 1757019
Crimping JST ACH Connector - Page 1
Forum section: electronics / projects

author: amaschas
author_rank: Regular Contributor
timestamp: August 03, 2023, 08:58:03 pm
content: Hey all, I recently decided to try out JST ACH connectors on one of my designs (these guys:https://www.jst.com/products/crimp-style-connectors-wire-to-board-type/ach-connector/) but I'm having some real trouble figuring out how to crimp the connectors, or even finding wire that will work. They're supposedly for use with AWG28-30, but I've yet to find any wire in either of those gauges with insulation that will fit inside the pins, and on top of that none of the crimping tools I have are small enough to effectively crimp pins that are 0.2mm. Does anyone have any recommendations for sourcing wire that might work in these connectors, and a crimping tool that do the job? The official crimping tool is $1,300, which is... outside my budget. I've ordered some pre-crimped jumpers for the time being, but I'd like to find a longer-term solution for this problem if there is one.

author: thm_w
author_rank: Super Contributor
timestamp: August 03, 2023, 10:19:18 pm
content: As per thedatasheet:QuoteYou can find 0.55mm 28AWG wire on digikey, its not the cheap PVC stuff you are trying to use, usually FEP or ETFE or something, as its tougher in that smaller diameter.For the crimper, there is one on ebay for ~$200, seems like a good price. Or consider getting a quote from a cable manufacturer.

author: amaschas
author_rank: Regular Contributor
timestamp: August 03, 2023, 10:51:32 pm
content: Quote from: thm_w on August 03, 2023, 10:19:18 pmHuh, I am not seeing an ACH crimper on eBay for that price. I actually couldn't find the YRS-1190 on eBay at all, which I assumed was because its a newer connector type. Cheapest I can find anyone anywhere is $1,300, which is just not worth it for the stage of the project I'm on. At this stage I'd solder the pins and deal with the downsides before spending $1,300 on a crimper. I'm picking up a PA-09, which can maybe do the job?

author: thm_w
author_rank: Super Contributor
timestamp: August 04, 2023, 12:18:01 am
content: I'm not a fan of PA09 but some like it. If you just need to make one or two crimps its fine, for any sort of production quantity its not useful.edit: the smallest die on PA09 looks to be 1mm for jst zh (1.1mm wide)? ACH is 0.8mm wide, may not be ideal.Here is the link:https://www.ebay.com/itm/394693724482I just saw "ACH" so you'd want to check if its the right one.

author: amaschas
author_rank: Regular Contributor
timestamp: August 04, 2023, 02:33:08 am
content: Quote from: thm_w on August 04, 2023, 12:18:01 amOh wow, it totally is! Thank you for the heads up!
Criteria when selecting an AC current sensor - Page 1
Forum section: electronics / projects

author: mike buba
author_rank: Contributor
timestamp: June 07, 2025, 10:47:21 am
content: Hi all. Can you please share what the criteria would be when selecting a PCB-based AC current sensor? From the electrical requirements I have:Nominal current = 10 ArmsVoltage = 400 VacFrequency = 50 HzThis is the list of sensors I have collected. So far the Allegro Micro ACS732, to me, looks like it fits the requirements the best. But are there any other factors and data I have missed... or any other suggestions I can look for in this application?ManufacturerModelTypeRangeSensitivityBandwidthVsInput resistanceOutputAllegro MicroACS758ACS772LCB-050B±50 A40 mV/A200 kHz+5 Vdc100 mΩTITMCS1101TMCS1100A1±46 A50 mV/A80 kHz+5 Vdc1.8 mΩLEMLAH 50-PLEMCASR 15-NPCASR 15-NP±20 A40 mV/A300 kHz+5 Vdc2.5 ± 0.625 VAllegro MicroACS37002PACS37002LLAATR-025B5±25 A80 mV/ALEMGO SMEGO 10-SME±10 A66 mV/A300 kHz5 V0.9 mΩ2.5 ± 0.8 VAllegro MicroACS732ACS732KLATR-20AB-T±20 A100 mV/A1000 kHz5 VTITMCS1123TMCS1123B2AQDVGR±80 A50 mV/A250 MHz5 V1.65 ±Regards, MB

author: Benta
author_rank: Super Contributor
timestamp: June 07, 2025, 11:40:16 am
content: Why not use a current transformer? Easy, cheap, lossless and immensely robust.

author: mjkuwp
author_rank: Unknown
timestamp: June 07, 2025, 11:48:59 am
content: You need to know the type of wave that will pass through the sensor. Is it a pure sine wave that results from a perfect AC source and a purely resistive load? Is it something more complex due to the load being something more complex? In other words, what is the bandwidth of measurement you require and what is the crest factor? Crest factor will tell you the maximum DC level you need to measure relative to your 10A RMS nominal load.

author: Benta
author_rank: Super Contributor
timestamp: June 07, 2025, 02:49:34 pm
content: Quote from: mjkuwp on June 07, 2025, 11:48:59 amGood point. High crest factor can bring the semiconductor current sensors to their knees, current transformes are pretty immune.

author: mike buba
author_rank: Contributor
timestamp: June 07, 2025, 03:35:52 pm
content: Quote from: Benta on June 07, 2025, 11:40:16 amThank you for the suggestion. I completely missed them in the analysis. The signal is AC output current from the three-phase inverter, so it will definitely contain some PWM harmonics (20 kHz and above).One techical basic question:Btw. I have also seen shunt resistors, also for measuring current. Apart from the current (for the transformer) and voltage output signal (for the shunt resistor), are there any major differences?

author: mjkuwp
author_rank: Unknown
timestamp: June 07, 2025, 04:53:47 pm
content: in this case it may be more important what your load is. If the load has high inductance (motor?), then your current may have a much lower frequency component than the pwm drive frequency. The output voltage would be a different story.
Heavy interconnect board layout - Page 1
Forum section: electronics / projects

author: Phaedrus
author_rank: Frequent Contributor
timestamp: July 30, 2014, 09:46:00 pm
content: I'm pretty much done designing this board, just wanted to put it out there and see if there's anything I might have missed, anything I can tweak or optimize, etc.Basically the board is an interconnect for a PSU semi-automated test system. It's the part where the PSU outputs, DC loads, datalogger, and oscilloscope probes all come together. I've also put together a voltage "sanity check" to visually indicate if PSU voltage is within a baseline +/-5% tolerance. If it is, the LEDs shine green. If it's out of that spec, the LEDs flash red. Pretty simple. Oh, and it's 300mm x 205mm.The board has to handle a lot of current, and I wanted it to be physically robust as well, as it's the point where the user comes into contact with the system. So it's built on 0.093" FR-4 with 2oz copper. This increases ampacity of the main current traces, but imposes limits on the voltage check section. You can't have spacing less than 0.011" between traces or pins, or most board makers can't make it without accidental shorts. Also the board has a lot of thermal mass, so I use thermal connections to the ground plane for most smaller components, rather than directly flooding it.Anyway, was just hoping for some constructive feedback. Thanks!PS: I chose discrete components over an MCU because this needs to be brain-dead simple and reliable... No random software issues to debug, etc. Plus, it's an excuse to use an NE555 and 74HC logic in a real, useful application, how can you say no to that?EDIT: I forgot to go back and change it in the schematic, but I decided C7 wasn't useful and decided instead to add a 100nF 1500mA ferrite bead instead.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: August 01, 2014, 04:12:06 pm
content: Shameless bump.

author: free_electron
author_rank: Super Contributor
timestamp: August 01, 2014, 04:20:37 pm
content: three transistors to turn on an led ? really ?now the obvious points are : since this is poer test : kelvin connections ? are you measureing where you need to measure ... i wouldnt use a plane for the return current in this case as you don;t know how it will flow.
Cross for Molex Click Mate - Page 1
Forum section: electronics / projects

author: AustinTim
author_rank: Newbie
timestamp: June 28, 2024, 07:56:06 pm
content: anyone know a cross for these parts?Even better would be an LCSC part.Molex CLIK-MATE 2.0MM PITCH W/B CONN. ST TYPE REC connectors?502443-0470502443-0370502443-0670https://www.mouser.com/ProductDetail/538-502443-0470

author: exmadscientist
author_rank: Frequent Contributor
timestamp: June 28, 2024, 11:42:06 pm
content: Intermateable or just similar-enough-spec?JST has a few things that match the smaller Clik-Mates but they do not intermate. I don't know that anyone offers a directly interchangeable cross.

author: AustinTim
author_rank: Newbie
timestamp: June 30, 2024, 05:56:50 pm
content: was hoping for inter-mate-able type cross, but that's always difficult for connectors.
Cross platform software for BM235 - Page 1
Forum section: electronics / projects

author: archie1983
author_rank: Newbie
timestamp: August 22, 2017, 09:19:06 am
content: Hi guys,Just heard the AmpHour episode #354 – A Meeting Of The Davids. What caught my attention was that the BLE module of BM235 communicates with software running on any platform-- Android, IOS, Windows, etc.Just a matter of professional interest-- how was that implemented? What development environment was used? What libraries? I am a software guy and am now working on a project where multi platform support is required and I would just like to get a perspective on what was used for BM235. In the past I've used GWT for creating browser based applications in JAVA that can be accessed by anything with a browser- hence multi platform, but I'd like to know what others are using. I would really appreciate some more technical details about multi-platform design tools that were used for BM235 software.Thanks.

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 22, 2017, 09:50:45 pm
content: Quote from: archie1983 on August 22, 2017, 09:19:06 amAre you sure it was the BM235 and not Dave's upcoming GW121? As far as I know, the BM235 does not support BlueTooth or any other communications functionality. The GW121 does have a BlueTooth module.

author: EEVblog
author_rank: Unknown
timestamp: August 22, 2017, 11:57:32 pm
content: It's the 121GW and I'll have to let David explain that.

author: EEVblog
author_rank: Unknown
timestamp: August 23, 2017, 12:19:15 am
content: BTW, it will all be open source, and David will eventually do a video explaining the development system
Crossing via tap - Page 1
Forum section: electronics / projects

author: sahko123
author_rank: Frequent Contributor
timestamp: August 08, 2020, 03:36:00 pm
content: Im designing a pcb for my project and i need to tap out some signals to an external connector. I want to know if its ok to have the via on an intersection rather than on the end of a wire or plane in terms of pcb manufacturing?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 08, 2020, 05:34:31 pm
content: That's fine. You can increase the pad size or add teardrops to improve yield. Or use two vias (connected top and bottom) to improve reliability if vias corroding through is common in your environment.Tim
Crowbar Circuit - Page 1
Forum section: electronics / projects

author: pspeirs
author_rank: Newbie
timestamp: August 22, 2013, 08:47:26 am
content: hi All,I'm trying to get a crowbar circuit working that will provide protection when using a plug pack. I'm using a 12V 1.4A plugpack and want to protect against a situation where I have a breakdown of insulation in the transformer and I end up with 240VAC on the circuit.I tried a simulation which seemed to work fine, however in real life it doesn't seem to be happening.Basically, we come in through a 2A fuse. A zener is in series with a 10k resistor between + and gnd. From the junction of the zener and resistor I go to the trigger of a triac which is again between + and gnd.Hope someone can steer me in the right direction here.Cheers,Paul

author: TerminalJack505
author_rank: Super Contributor
timestamp: August 22, 2013, 02:31:14 pm
content: You might try something like the attached circuit. The cap is to filter out transients. I didn't model that part so it might need to be tweaked. It won't need to be nearly as big as what you used in your schematic.You didn't say so I assumed the input voltage is AC.

author: Harvs
author_rank: Super Contributor
timestamp: August 23, 2013, 01:20:42 am
content: Quote from: pspeirs on August 22, 2013, 08:47:26 amIf you're using a half decent quality plug pack, that's not a very likely scenario. On an off-line transformer you have three layers of insulation to get through, the enamel coating on the primary, on the secondary and a tape barrier between the two. On a properly made transformer the only real way this can happen is through catastrophic over-heating (i.e. smoke etc.) Any decently made plug-pack will have protection against conditions that could cause this, in the case of the old iron core transformer they typically have a thermal fuse and for SMPS's there'll be current limiting etc.Assuming you still want to protect against the scenario of insulation breakdown, I don't see that simply crow-baring the output is going to be effective. Your typical off-line plug-pack is generally fully isolated from input to output, meaning if you have a breakdown in insulation at one point in the transformer, then you could end up with a high potential relative to earth not across your output terminals. In this, which I see as the most likely case, the output could still be within normal range yet be sitting on top of 240VAC relative to earth. But this is where having a RCD (GFI in US) will hopefully save you.My 2c is just buy quality plug-packs and have a working RCD (GFI).

author: pspeirs
author_rank: Newbie
timestamp: August 23, 2013, 09:53:43 am
content: Agreed, the scenario would be rare, but for what its worth for a couple of components, worth the effort blowing fuses up on the breadboard. That kept me busy for 30 minutes or so. Still have some thinking to do with the whole idea, but as you've said any half decent plugpack will have protection built in.Cheers,Paul
Crsytal Oscillator Test - Page 1
Forum section: electronics / projects

author: kfc_n
author_rank: Contributor
timestamp: May 21, 2014, 02:25:54 am
content: Any Idea on how to test crystal oscillator if it is still working properly without oscilloscope, or just by multimeter? thanks..

author: Vgkid
author_rank: Super Contributor
timestamp: May 21, 2014, 02:48:30 am
content: Do you have any logic chips. What frequency is the oscillator?

author: kfc_n
author_rank: Contributor
timestamp: May 21, 2014, 03:17:59 am
content: I went out for a while and went to my friend with oscilloscope...tested it and its working, thanks anyway..

author: TVman
author_rank: Frequent Contributor
timestamp: May 21, 2014, 03:58:01 am
content: Quote from: kfc_n on May 21, 2014, 03:17:59 amYou shuold get an ociloscope.

author: sfiber
author_rank: Regular Contributor
timestamp: May 27, 2014, 09:17:46 pm
content: there is a way to test the oscillator is working or not.you solved your problem but I even so explain how it is.you can you clock divider or 8 bit johnson counter to reduce clock cycle and you can see it on led with 330 ohm resistor or you can use a circuit like this.http://www.electronicecircuits.com/wp-content/uploads/2009/12/crystal-tester-XTal-Tester-circuit.jpg

author: w2aew
author_rank: Super Contributor
timestamp: May 27, 2014, 09:33:26 pm
content: Depending on its operating frequency, you can often use a shortwave radio receiver to "hear" if it is oscillating...

author: dannyf
author_rank: Super Contributor
timestamp: May 27, 2014, 10:16:58 pm
content: An RF probe can be easily made with a diode, a resistor + two capacitors.
CRT Deflection coils to composite video? - Page 1
Forum section: electronics / projects

author: ALearningLad
author_rank: Contributor
timestamp: January 17, 2022, 12:54:40 am
content: Just had a shower though of can you use a micro controller like a Arduino or raspberry pi to take the signal to the deflection coils. Then translate it into a composite/VGA/whatever video signal. Couldn't see anything like that online. Can someone also explain why you could or could not, thank you!I will not do anything with this but just want the answer. Not screwing with crts as a novice.

author: CaptDon
author_rank: Super Contributor
timestamp: January 17, 2022, 02:34:15 am
content: Answer.....NO! There is no information contained in the deflection sweep voltages. Only the scanning sawtooth waveform.

author: ALearningLad
author_rank: Contributor
timestamp: January 17, 2022, 04:15:54 am
content: Ah thanks for the response, haha feel like a dummy now. Does make perfect sense however.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 17, 2022, 04:57:45 am
content: Quote from: CaptDon on January 17, 2022, 02:34:15 amExcept for vector displays, those use specific waveforms that trace out the desired shape. In the days when those were in common use, the main advantages were better resolution and very high dynamic range.

author: PKTKS
author_rank: Super Contributor
timestamp: January 17, 2022, 03:53:35 pm
content: Quote from: ALearningLad on January 17, 2022, 12:54:40 amWhy bother if the 80/90s decades of VLSI already provided us witha TON of good chips to do so reliable?Some attached here and can be easily found even today..Paul

author: PKTKS
author_rank: Super Contributor
timestamp: January 17, 2022, 04:01:47 pm
content: ALAS...If you are wondering for something moremodernthansimple CRT deflections.. e.g. resolutions like multisync monitors..Try this one still found ... todayPaul

author: Terry Bites
author_rank: Super Contributor
timestamp: January 17, 2022, 06:26:54 pm
content: I'm about to take a shower myself...

author: PKTKS
author_rank: Super Contributor
timestamp: January 17, 2022, 07:47:03 pm
content: hmm almost left aside... if you are going to drive the yoke..A handy small standalone tip...Paul

author: james_s
author_rank: Super Contributor
timestamp: January 17, 2022, 07:49:56 pm
content: It's actually the current through the coils, not the voltage across them that determines the beam position.Either way you would be much better off just taking the H and V sync signals, and then of course no matter what you do you need to sample the intensity signal to the electron gun to get your video image. If you only looked at deflection current you'd just get a blank raster.
Crushed camera disassembled - Page 1
Forum section: electronics / projects

author: atferrari
author_rank: Frequent Contributor
timestamp: November 03, 2014, 09:53:05 pm
content: Wish I knew more about this subject.Having read lately a lot about VCM (voice coil motors) I recalled a camera crushed by a car, given to me two weeks ago.Expecting to find one VCM inside, I disassembled the optical block. In the attached .pdf I show the pictures of what I could find and eventually recognize.As usual with my posts, hardly you could learn something, and, if after reading it, you feel that you have wasted your time, sorry. I already spent mine along two afternoons. Let's share...

author: paulie
author_rank: Frequent Contributor
timestamp: November 03, 2014, 10:16:44 pm
content: QuoteCorrect-a-mundo, on both counts. They are available on Ebay for pennies a piece and are not surplus:http://www.ebay.com/itm/10pcs-New-6mm-2-Phase-4-Wire-Camera-Step-Stepping-Stepper-Motor-with-Slider-Bar-/331227803818?pt=LH_DefaultDomain_0&hash=item4d1eb730aaThey were were mentioned in a recent post of mine here for their ability to be driven directly from AVR pins. Ive purchased dozens as part of my ongoing "$15 photo-plotter/PCB-exposer" project.BTW I also enjoy dissecting cameras as a hobby. Whenever they pop up on a flea market table for $2-$3 it's hard to resist. Endless supply of micro optics, motors, and other weird components.

author: void_error
author_rank: Frequent Contributor
timestamp: November 03, 2014, 11:41:35 pm
content: The second motor is a bipolar stepper, like the ones found in floppy drives or some optical drives, except smaller.
crying metal detector help needed - Page 1
Forum section: electronics / projects

author: dave_j_fan
author_rank: Regular Contributor
timestamp: June 16, 2022, 07:06:37 am
content: This one i madetransistors selected bc547 .pin diagram is matched .but coils made from enamelled aluminum wires.after making1.when i take metal near right side coil it works as we can hear frequency change2.but oscilation is always there smallbuzz there even without metalnearby one coilyoutube video shown it gets silent without metal nearbyhow can i fix it?please suggest modification or tuning

author: tepalia02
author_rank: Regular Contributor
timestamp: June 17, 2022, 12:15:47 pm
content: I never tried one. But I think this problem can be gone by changing the values of the capacitor used. You can give a try to this ckt.https://www.circuitstoday.com/metal-detector-circuit

author: dave_j_fan
author_rank: Regular Contributor
timestamp: June 17, 2022, 02:48:36 pm
content: that is radio assisted...i want to do stand alone one

author: tepalia02
author_rank: Regular Contributor
timestamp: June 21, 2022, 10:32:13 am
content: Oh I see. This video shows a standalone metal detector. I can see it is quite similar to your circuit. But I can see that the capacitor values are different:

author: ledtester
author_rank: Super Contributor
timestamp: June 21, 2022, 11:05:50 am
content: There is a very simple metal detector kit you can get on ebay/aliexpress for about $1 that looks like this:and here is a video explaining how it works:Building a metal detector & how does it work -- DiodeGoneWildhttps://youtu.be/Bs9U15qQo0EIn subsequent videos DiodeGoneWild goes on to develop his own design.
Crypkey and Sentinel - Page 1
Forum section: electronics / projects

author: GBH
author_rank: Newbie
timestamp: February 04, 2018, 05:41:55 pm
content: Hi Guys,I am a fire alarm engineer from UK, a recent change in employment to a new fire alarm company has meant that i can no longer access certain software without a site key or a USB dongle.I am wondering if anyone can help me with Crypkey which requires a site key to allow the software to work and Sentinel which requires a hardware key.I am looking for a site key generator mostly, the others i can live without and release the clients contract to the manufacturer which is not what the client wants. However the Crypkey generator is a necessity as i look after most sites with the system that requires the Crypkey protected software.Hopefully some of you can help me as i am bashing my head against a wall because i just do not know enough about the software.ThanksGBH

author: Marco
author_rank: Super Contributor
timestamp: February 04, 2018, 05:55:41 pm
content: The company selling the software has a generator they are willing to use for you in exchange for money.

author: GBH
author_rank: Newbie
timestamp: February 04, 2018, 07:22:43 pm
content: While that is a consideration, I am looking to see if anyone has a copy of it they wish to share and if anyone has the knowledge to get it working.

author: GBH
author_rank: Newbie
timestamp: March 28, 2018, 05:29:07 am
content: Bump, hopefully someone can help me with this.

author: BravoV
author_rank: Super Contributor
timestamp: March 28, 2018, 05:39:47 am
content: Quote from: GBH on February 04, 2018, 05:41:55 pmAs English isn't my native, cmiiw, are you asking people here to give you pirated stuffs ?Quote from: GBH on February 04, 2018, 05:41:55 pmHow do we know if you're not going to sell/charge for the generated key ?Are you willing to share the profit made ?

author: Simon
author_rank: Unknown
timestamp: March 28, 2018, 06:57:45 am
content: We dont do pirate software on here particularly for commercial use.
Crystal bandpass filter as oscillator - Page 1
Forum section: electronics / projects

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: December 15, 2012, 03:26:56 pm
content: I am having some problems finding crystals for the same frequency as IF filters in a receiver (10.7, 21.4 or 45MHz).I wonder if an extra filter can be used in place of a crystal in an oscillator.Filters are essentially made from a series-connected crystals (usually on the same die) with a shunt cap(s) to widen their bandwidth.I can't find any references to such use.Leo
Crystal drive level approximation or typical value? - Page 1
Forum section: electronics / projects

author: shadewind
author_rank: Frequent Contributor
timestamp: September 22, 2011, 01:53:24 am
content: I chose to use the TXC 7M series crystals for a recent project because they were small and seemed nice. When I chose them, I unfortunately didn't know know about the concept of drive level. The TXC 7M series specify a maximum drive level of 50 micro watts (I assume that's what 1 ~ 50 means). My fear is that this is too low for my design. I'm wondering I there is some approximation that can be done or if there is some typical value that is common. One of the devices is an STM32F micro and the other is an TI CC2500 RF transceiver.I have read an STmicro app note about the subject but it only says how to measure it and I don't have the equipment to do that.This is the datasheet for the crystal:http://www.txccrystal.com/images/pdf/7m.pdf
Crystal Filters - Page 1
Forum section: electronics / projects

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 26, 2015, 03:08:53 am
content: Question:What are the typical spurious modes of an average AT cut crystal? (Is there such a generalization?)I'm building a crystal filter for 4.000MHz, and finding a rather strong, and very sharp, peak at 4.30MHz... needless to say, this is undesirable!Tim

author: kjs
author_rank: Regular Contributor
timestamp: January 26, 2015, 03:45:44 am
content: These spurious modes are very dependent on the quality of the cut (angle) and the quality the disc was made (flatness amongst others) as well as the quaity the ingot was grown and how clean it is but they are always there. Just more or less suppressed. The worst thing is that these spurious modes have a different Tk than the nominal frequency and when they drift close to the main mode you get the thing jumping between the two frequencies (in an oscillator). In a filter you just get a lousy shape.....Juergen
Crystal load capacitance - Page 1
Forum section: electronics / projects

author: shadewind
author_rank: Frequent Contributor
timestamp: August 29, 2011, 02:43:27 pm
content: I'm trying to figure out what loading caps to use for the crystal oscillator for a TI CC2500 (http://www.ti.com/lit/ds/symlink/cc2500.pdf).The following formula is the one most commonly seen and the one I'm using: C(L) = (C1 * C2)/(C1+ C2) + C(S)...where C(L) is the crystal specified load capacitance, C1 and C2 are the values of the loading caps and C(S) is the parasitic capacitance of the board and oscillator pins. The crystal I want to use (http://se.farnell.com/txc/7m-26-000maaj-t/xtal-26-000mhz-18pf-smd-3-2x2-5/dp/1842069) has a load capacitance of 18 pF which would mean C1 = C2 = 31 pF if you, as the data sheet suggests, assume that the parasitic capacitance is 2.5 pF. The closes value would me 33 pF which to me seems very high and there is no such value among the examples at page 50 in the CC2500 data sheet. 18 pF seems like a fairly common value for crystals but I'm wondering if this is too high or if 33 pF is simply a normal value for the caps?
Crystal Oscillator Layout - Page 1
Forum section: electronics / projects

author: luky315
author_rank: Regular Contributor
timestamp: November 17, 2023, 07:31:42 pm
content: I am asking myself if it is worth breaking a few "good design practices" like never make a trace leaving a SMD pad with an angle other than multiples of 90° for a shorter trace to the crystal (CFPX-180 package in this case)It looks a bit wrong and also a bit strange to me using variant 2, so what do you say?

author: Benta
author_rank: Super Contributor
timestamp: November 17, 2023, 09:36:46 pm
content: I see no problem with the angles.But I see a problem having no thermal reliefs on your ground plane. Big potential for bad solder joints.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 17, 2023, 10:08:02 pm
content: Quote from: luky315 on November 17, 2023, 07:31:42 pmWhat difference do you think it will make?

author: MarkT
author_rank: Frequent Contributor
timestamp: November 18, 2023, 09:56:49 am
content: The only issue I see is that the 45 degree trace slightly encroaches on the other pad - normally this would be a design-rule error, but here the pad has its corner cut-off which isn't great, not that its an actual problem as its microns.Its just a crystal, not an oscillator, BTW.

author: luky315
author_rank: Regular Contributor
timestamp: November 20, 2023, 08:38:51 am
content: I don't use thermals on my GND plane for SMD components except on very big inductors and I never had a problem, they are soldered by hand, reflow and even vapor phase.
Crystal oscillator near board edge - EMI concern? - Page 1
Forum section: electronics / projects

author: blueduck577
author_rank: Newbie
timestamp: December 13, 2018, 08:34:54 pm
content: I'm currently laying out a board which includes ethernet and the requisite PHY. In the current arrangement, it would make my layout nice and tidy to orient the PHY such that that the 25 MHz crystal oscillator will be close to the board edge. Close is 0.1-0.2" from the edge.Would placing the oscillator here be a bad idea for EMI? The board is 4 layers with two internal planes. This board will eventually go into a commercial product and thus will be subject to EMC testing. The board will mounted on a drawer with a metal drawer rail right next to the side in question. The enclosure is all aluminum.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 13, 2018, 08:52:08 pm
content: Funny, I did that just the other week (the boards came in; no, I don't have any pictures handy). They haven't been to the test lab yet, though.Do you have a tentative layout to discuss?Consider the facing surface of the clock trace. How close it it to the edge? All parts of the net: trace, component pins, vias, the whole path. Is it surrounded by ground? (Ground fill on the top side is best, but inner layer ground on a 4+ layer board is a close second and almost always adequate!) How sharp is the oscillator, are harmonics a hazard relative to the trace length (as an antenna)?A metal enclosure can cure a lot of ills, but aren't magic. You may need to grind off paint or anodization from mating surfaces, perhaps add EMI fingers as well. Consider that every seam, gap or opening is an aperture, which can transmit some range of frequencies corresponding to its size. If you happen to induce currents which flow directly across those openings, they will radiate.Tim

author: rhb
author_rank: Super Contributor
timestamp: December 14, 2018, 03:50:13 am
content: I can't say a priori about a design, but a scope probe without a ground lead or grabber is an amazingly sensitive E field EMI probe. I made a little "condom" out of heatshrink to preclude shorts and it is amazing how sensitive it is on the 1 mV/div scale. With about a 1/4" extending past the shield it doesn't detect anything until you are very close to the source. A small loop of copper wire makes a very effective H field probe.I have been quite amazed at the EMI from the LCD screen on my Keysight 33622A at 1-2 inches.