hybridfree/eevblog-posts huggingface dataset:
Designing a PSTN/POTS ringing detection for uC? (AC-DC PSU with wide op. range) - Page 1
Forum section: electronics / projects

author: thejoggingmat
author_rank: Regular Contributor
timestamp: May 21, 2016, 03:36:49 am
content: How can I design a reliable POTS/PSTN ring detection circuit?I tried designing a capacitive dropper hooked up to an optocopuler based on this datasheet (http://ww1.microchip.com/downloads/en/AppNotes/00954A.pdf,schematic as per page 2 fig 1 with different component values) and while it works at the nominal AC ring voltages (as per the specifications published by the governing body), it's rather unreliable at the lower end or upper end of the voltage range. Also, when the phone is off-hook, it sometimes triggers the circuit as well.There is an enormous voltage range that is needed to work on. Requirements:-Vmax, rms: 100V-Vmin, rms: 30V-Vnominal, rms: 70V-Freq: 24Hz, +/- 2HzI'm using PC817 optos with appropriate resistors.

author: Len
author_rank: Frequent Contributor
timestamp: May 21, 2016, 05:33:33 pm
content: A quick google shows lots of ring detector circuits, for example:http://electronics.stackexchange.com/questions/52835/switch-small-dc-voltage-with-90v-30hz-ac-signalhttps://www.velleman.eu/downloads/0/illustrated/illustrated_assembly_manual_k8086.pdf(I have not tried any of these.)Many of them have a pair of zener diodes to limit the AC voltage, maybe that's the trick you're missing.
Designing a room? - Page 1
Forum section: electronics / projects

author: rosaage
author_rank: Newbie
timestamp: January 02, 2018, 09:12:48 pm
content: Hello,I'm designing a new work room for my gaming rig, vintage PCs, long term storage and Lab area. a rough sketch of my current plan (see attatchments)This is inside our barn, we have a few rooms already but this space is currently empty so I would have to put up inner walls with insulation and wiring.Should I go for something like this:Or just normal outlets? I plan to have my electronics equipment set up, is there something useful I should know? I have a scope, signal gen. bench psu, variac, soldering station and various tools and stuff. We have 3 phase 400V in the barn, should I put up a 16A 3 phase outlet over the bench?is there anything else I should think of that can become useful as my lab grows and I get more stuff?*EDIT, added the pictures

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: January 02, 2018, 10:05:59 pm
content: Hei rosåge!If it were me I would try to have all the surfaces in same height, and the shelves (OCD?). And you should conciser making the 'island' be on coasters so you can place it behind you too. That small gap will probably be a bit annoying with stuff/projects/mess on itAs for outlets, my guess would be that you don't really need the modularity of a rail like that. It's handy if you plan to change positions or add/remove certain sockets (such as Ethernet) but for a room you know the purpose of? Just make sure you have enough sockets at floor and bench height. If I could have a three phase accessible I'd not hesitate to add it (comes in handy for certain applications).These are just my 2 bits, and I think whatever you choose will probably lead you to be happy.Oh, and make sure to get the correct sockethaha

author: David Hess
author_rank: Super Contributor
timestamp: January 03, 2018, 12:35:45 am
content: For a room where i work, I prefer surface mounted outlet boxes and conduit so I can place them exactly where I want them. Workbenches can have their own outlet strips and power switches or circuit breakers built in. If a workbench has a shelf under it, then that is a good place to put a heavy isolation transformer and online UPS for expensive test instrumentation.
Designing a USB multi-channel audio 2.0 device - Page 1
Forum section: electronics / projects

author: joseph.anand
author_rank: Regular Contributor
timestamp: July 15, 2012, 08:54:44 pm
content: Most USB audio devices in the market either implement the USB audio 1.1 audio spec (limited to 2channels) or implement non-standard formats.I am working on designing a USB multichannel (more than 2) audio 2.0 device. Since the cost and availability (in India) are major factors, I am wondering if I should go ahead with a dual stereo codec like WM8731 interface via the dual i2s channel of the PIC32MX2 series. Alternatively I can use the DSPIC33EP256MU806 with multichannel codecs (like PCM3168) from TI using TDM mode. But this would be too expensive.The requirements for this device1. 4 to 6 channel audio input, 2 to 6 channel audio output2. At least 16 bit audio at 48kHz3. Cost and availability4. Codec features (PGA etc)The USB interfaces in the PIC32MX2 and the DSPIC33EP256MU806 are limited to full speed mode. So they might just be sufficient for 4 channel audio.ps: Please do not make this thread into a PIC vs others argument. Just suggestions on cost effective and easily available options would be good.

author: amyk
author_rank: Super Contributor
timestamp: July 16, 2012, 09:46:45 am
content: You might be better off going with an all-in-one ASIC. Something like a CM6206 or similar, don't know if they make them with that many channels though.

author: eliocor
author_rank: Unknown
timestamp: July 16, 2012, 09:58:49 am
content: Maybe you can be interested in theXMOSchips:http://www.xmos.com/products/development-kits/usbaudio2[added some minutes later...]http://www.xmos.com/products/development%20kits

author: joseph.anand
author_rank: Regular Contributor
timestamp: July 16, 2012, 08:46:44 pm
content: XMOS is not easy to get (especially in India), and expensive for a hobbyist's project.As for the CM6206, it is a USB audio class 1.0 and limited to 2 input channels.

author: amyk
author_rank: Super Contributor
timestamp: July 17, 2012, 08:57:33 am
content: http://www.via.com.tw/en/products/audio/controllers/envyusb/Might be just as hard for you to get, and I don't know of the cost, but otherwise I think it meets your requirements.

author: sandeepkolluri
author_rank: Newbie
timestamp: June 15, 2015, 02:50:53 am
content: Quote from: joseph.anand on July 15, 2012, 08:54:44 pmhai joseph, i have been searching for the same concept that you raised in this post... plz share the information if you already got it. i'm from india too.. actually 'mi planning to build/modify analogue audio mixers to digital console at low cost using this method with USB 3.0 intrfac features. plz reply me to this topic. I'll later post my concept. Thank you.
designing a variable single output DC to DC - Page 1
Forum section: electronics / projects

author: BelAir
author_rank: Newbie
timestamp: September 17, 2015, 08:25:55 am
content: Hi,I am a new here. I have a few enquiries regards designing a variable single output DC to DC convereter, please:- is there any way to generate a single output can be swing/ variable from -5 to + 5 vdc base on the load requirements, input voltage +/-15 or +/-10 doesn't matter here as i can choose any! Also the maximum current must be 500mA.- i have found plenty of schematics for dual outputs -/+ve but doesn't come as a single output.- I have also used dual inverteing and no inverting op amp and linked the output to POT to provide me a single output from -5 to +5 but with low current 10mA!!.Your help and efforts are really appreciate.Cheers,BelAir

author: nctnico
author_rank: Super Contributor
timestamp: September 17, 2015, 09:42:04 am
content: Look for a class-D amplifier. You'll need some filtering at the output though.

author: BelAir
author_rank: Newbie
timestamp: September 17, 2015, 12:51:21 pm
content: Thanks indeed nctnico ..

author: matseng
author_rank: Frequent Contributor
timestamp: September 17, 2015, 02:32:41 pm
content: Quote from: BelAir on September 17, 2015, 08:25:55 amHave you seen the OPA541 and its siblings?The OPA541 is a power operational amplifier capable of operation from power supplies up to ±40V and delivering continuous output currents up to 5A. Internal current limit circuitry can be user-programmed with a single external resistor, protecting the amplifier and load from fault conditions.That might be an easy solution for your requirements. The 541 is a little bit too beefy for you but there are lower powered versions of it.
Designing a volume & power switch for an old McIntosh Preamp - Page 1
Forum section: electronics / projects

author: neevo
author_rank: Newbie
timestamp: April 26, 2024, 12:42:02 am
content: Hello everyone! I have over the past few years been restoring a beautiful McIntosh C20 Tube Prepamplifier. These date back to the 1950-60's and are a glorious bit of kit. My restoration is now complete and I had to make a few parts along the way as these things are no longer supported by McIntosh for a lot of items (understandably so given the age). I documented the whole build process for anyone who is interested on a popular Audio forum.My latest project is to build a replacement volume and power switch as these are known to go bad on a few vintage McIntosh machines and are also no longer supported. There are reproduction parts available which I have in my C20 (and its working fine), but they are supposed to be all over the place in terms of quality... so I am looking to make a better version that also has the option of being rebuildable if required and also tunable to dial it in perfectly.The original C20 volume potentiometer has 4 wafers (audio) and a rotating switch all in the same assembly:The repeated use of the switch is what seems to kill these pots, plus the balance between all the 4 wafers is not even that goodMy design uses 4 stepped attenuators but where I am getting stuck is the switch mechanism and thats where I need some help:I am keen to get rid of the mechanical switch if possible as I think I can get more control from a low voltage wiper and activate something like a relay or Triac. I could use a microswitch, but I find them a pain to set the trigger point and given the stepped attenuators ativate in 10 degree increments, I really want to activate the switch on the first 1 or 2 steps. So my thoughts were to use a voltage divider network to trigger a triac, all using the 120v line voltage on the original switch:When I simulated this, it looked like it would work but I am not 100% sure and keen to have some experts help me understand to make sure its effective + SAFE! Ideally I would like to put this all on a PCB on the end of my design which also would need to allow for the 120v and 35w of power the C20 uses. The simulator showed only 740mv and 70 uA on the switch, which in concept seems like it will work. But I cannot be 100% sure I haven't used the simulator wrong or made some basic errors.Hoping to get some guidance here.
Designing button that closes switch only after being held down for some time - Page 1
Forum section: electronics / projects

author: polar8
author_rank: Contributor
timestamp: April 12, 2013, 05:51:58 am
content: I am building a blinky light for my bicycle, and I would like it to turn off automatically when my bike is hung from the ceiling in my apartment. I am envisioning a tilt switch that closes in this position, and some supporting circuitry that requires the tilt switch to be closed for x amount of time before the light turns off.I guess a simpler way of stating this problem would be to say I want to make a button that completes a circuit only after being held down for some time.Any ideas? Thanks!

author: nuhamind2
author_rank: Regular Contributor
timestamp: April 12, 2013, 06:04:04 am
content: Button to charge RC circuit, then comparator (can be opamp) to turn on switch.perhaps can be made with single 555 since it has built in comparator

author: Unknown
author_rank: Unknown
timestamp: April 13, 2013, 03:09:09 pm
content: Yes, I would go with that idea too... 7555 the C-MOS version has low power and ideal for battery supplies, have a look at the below application circuits or search the internet with 555, you will have tooo-much to go through.

author: ramicio
author_rank: Regular Contributor
timestamp: April 16, 2013, 12:58:14 pm
content: I made a circuit for an amplifier that requires one push of a button to turn it on and holding it a few seconds to turn it off. I used a PIC because I don't really understand passives and I have no idea how I would even make an RC circuit that doesn't oscillate.

author: SeanB
author_rank: Super Contributor
timestamp: April 16, 2013, 03:43:09 pm
content: I did something similar to only activate a door release if held down for around 5 seconds. It used a SCR and a RC delay along with a zener diode. Works a treat for a couple of years now.
Designing electronics enclosures for IP66 and waterproof applications - Page 1
Forum section: electronics / projects

author: leonhart88
author_rank: Regular Contributor
timestamp: January 14, 2015, 07:37:21 pm
content: Hey All!This may be a relatively uncommon question on the forum, but I am in the midst of designing a hand held device which needs to meet IP66 or IP67 requirements for water ingress.I've never had to do this before so I have no idea how the pros do this. Since I'm starting out with small quantities, the enclosures will either be off the shelf, or I'll have them machined. No fancy injection molding processes.Does anybody have experience in doing these types of applications? Do I just need to get/make an enclosure that meets IP66/67, and then purchase buttons and switches that are also rated for IP66/67 and come with a gasket to seal them into an enclosure cutout? This needs to be easily assembled so I'd want to avoid using any liquid gaskets that require labor intensive applications.Also, if anybody does have experience with injection molding waterproof cases, I'd be interested in knowing how they make the membrane buttons and stuff.Thanks!
Designing extremely low current voltage detectors - Page 1
Forum section: electronics / projects

author: pyrohaz
author_rank: Regular Contributor
timestamp: January 08, 2015, 04:34:43 am
content: Hey all,I'm wondering how rechargeable battery powered electronics manage to cut off the battery from the circuitry to prevent overdischarge. I've designed a really simple low voltage detector with a tune-able cutoff voltage set by a potential divider. Obviously, the accuracy is pretty poor, its device dependent and temperature dependent so I'm wondering how this is generally done? I'll attach a pic of my sim if anyone is interested!Cheers,

author: TerraHertz
author_rank: Super Contributor
timestamp: January 08, 2015, 04:50:42 am
content: Search for 'lithium cell protection' and '18650 discharge protection' on ebay. Lots of cheap examples for reverse engineering. Or just to use as-is.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 08, 2015, 11:45:33 am
content: Typically using extremely low bias comparators, which due to their low current, operate extremely slowly (~10us for the fastest ones, up to ~ms). They are internally constructed with MOSFETs, gigohm resistors and CMOS logic.The biggest challenge in designing such circuits is getting a reliable voltage reference. The traditional bandgap reference, as with most circuits, exhibits noise proportional to sqrt(I). At low currents, shot noise dominates, meaning, the voltage fluctuates up and down in rather huge steps (~mV?). For a battery monitor, this makes it very difficult to precisely gauge state-of-charge and cutoff.Trying to build a discrete version is kind of silly, because you need that low noise reference at some point. Constructing a bandgap from discrete transistors is impractical (too temperature sensitive), and may not have good results anyway (a 2N3904 is probably 10,000 times larger than the transistors used for internal references, so the current density will be extremely low, and therefore hFE will be poor). Using a commercial micropower reference is kind of cheating (it's an IC, so why not add a few more internal transistors for one of those ref-comparators or full on monitoring chips), and not quite good anyway (often, the comparison itself will be accomplished by monitoring when the bandgap turns on -- this is how many voltage regulators, like LM317, operate, using the reference as the error amplifier).Tim

author: pyrohaz
author_rank: Regular Contributor
timestamp: January 10, 2015, 02:18:19 am
content: Quote from: T3sl4co1l on January 08, 2015, 11:45:33 amThat's very well explained! Thank youf or your time.Quote from: TerraHertz on January 08, 2015, 04:50:42 amI had a look on aliexpress to find out how the ultra cheapies do it and there seems to be a magical protection chip called the DW01 which when used in conjunction with a dual mosfet IC, you have a battery protection circuit! Thanks!
Designing, Fabrication and Calibrating EMC magnetic Probe - Page 1
Forum section: electronics / projects

author: Rebelnation
author_rank: Newbie
timestamp: December 05, 2013, 11:58:23 am
content: Hey guys,I need to design, fabricate and calibrate EMC h field magnetic probe (circular design). i need tips on how to do it such as does the area of loop effects the magnetic wave obtained and how do i measure the area, any other formulas or books or anything related to this. what kind of hardware need and how to calibrate it and also is any software available to design it and simulate if possible. Any tips is greatly appreciated and thanks

author: qno
author_rank: Frequent Contributor
timestamp: December 05, 2013, 12:55:34 pm
content: Check out Application note 118 of Linear Technologies
Designing Mini-PC with x86 architecture.  - Page 1
Forum section: electronics / projects

author: firasgany7
author_rank: Newbie
timestamp: January 21, 2021, 09:37:12 am
content: Hello,I'm a beginner Hardware Design Engineer, and the next project that I will take is designing a mini-PC that includes intel CPU (x86 architecture).I will be in charge of designing the Motherboard (Schematic and placement). Routing usually done by freelancers but we give our judgment on their work.I'm aware that a good source to learn all the stuff that I will need for schematic is to look at previous project done in the past (in my company) in addition to the documents provided by intel regarding layout and schematic, and for sure, asking for help from highly experienced engineers that work with me. and because designing a whole motherboard is very difficult and complex process, my company will put an adjacent engineer that will help me through.In addition to all of this, I am an autodidact that always love to learn faster from additional sources.I was wondering if there is a course (free or paid) that is specified for x86 Architecture using modern generation of the CPU's that might be a good way to start learning.Thanks,Firas
Designing new home domotic sensor power distribution - Page 1
Forum section: electronics / projects

author: Robotec
author_rank: Contributor
timestamp: February 26, 2025, 11:00:52 am
content: Hello Everyone,I´m in the process of buying a new home and I'm thinking about the power distribution, the idea is to have several sensors communicating over WIFI, Zigbee ,etc but many of them (like aqara FP1 and FP2) require mains power supply so my needs are the next:Idea is to run the power and sensors inside the false ceiling.System have to be more reliable than typical Chinese USB charger (never had a problem but I'm quite afraid to leave this power supplies running for years).wiring cant be seen->WAF(Wife Approval Factor).My idea has been the next:I'm going to put a cabinet with the home assistant pi, router, etc together, and add a good quality AC to 48V power supply. Then in each sensor install a 48V/5V converter.The idea for the future would be to monitor the 48V rail to detect current spikes and cut off supply (in the event of failure of a converter).Is this too complex and should I go for just distributing 220V ac to all sensors?, anyone has gone through this?

author: Marco
author_rank: Super Contributor
timestamp: February 26, 2025, 02:38:19 pm
content: Why not pull Ethernet with PoE. If you sell the house at least people will understand what they are looking at.

author: Robotec
author_rank: Contributor
timestamp: February 26, 2025, 05:53:18 pm
content: Quote from: Marco on February 26, 2025, 02:38:19 pmIt has crossed my mind as well but this would require a cable from each sensor to the cabinet or a POE switch in each room and from that switch to the cabinet room which would be way more expensive.But you are right, having in mind that it should be a standard system that other people dont have to do a masters to understand should be a design request as well and makes me go for the 220V AC to 5V DC which is normal nowadays.
Designing power supply for 24/36V M-bus - Page 1
Forum section: electronics / projects

author: okw
author_rank: Frequent Contributor
timestamp: January 18, 2022, 03:46:15 am
content: My current meter has a standard HAN port for reading my power consumption at home.The HAN port is a RJ45 with two active pins: +24V_MBUS_TX and GND.According to the technical documentation for my meter, the HAN port can supply up to 700mW. The docs does not specify anything more.In the old M-bus spec, it says logical 0 is 24V and 1 is 36V.https://m-bus.com/documentation-wired/04-physical-layerObtaining the new spec is of course silly expensive. ​I could of course hook up the oscilloscope and measure a bit.But a fairly new M-bus interface, TSS721A, ​mentions 24 and 36V:V_Sampling_capacitor = 24V.V_Differential_bus_voltage_after_rectifier = 36V.So I assume these are voltages they get from the bus, and regulate down to 3.3V.My question is, which is the most efficient and proper way to design a 3.3V supply powered from the +24V_MBUS_TX and not interfere with the data (9600 baud i think)?I'm powering an ESP12, LM358 and possibly a tiny OLED.How will the input 36V jumping affect the regulator (it only happens for a few hundred bytes every minutes and then stabilizes at 24V, so it might be negligible)? And most regulators needs input caps. Would a series inductor "isolate" the caps so the data edges are not smoothened?Anyone with suggestions for regulators too (I'm open to reputable vendors, or a popular/cheap ali part).
Designing products to safety standards - Page 1
Forum section: electronics / projects

author: Northy
author_rank: Regular Contributor
timestamp: September 25, 2020, 03:43:11 pm
content: I'm looking at the new (to me) standard EN 62368.How does everyone go about getting together a list of the requirements that's in more of a tick list or compliance matrix form?I don't mind reading standards but reading the standard cover to cover isn't really that helpful IMHO, a list of what's required to pass each test would be much more beneficial.What does everyone do?Thanks,G

author: Benta
author_rank: Super Contributor
timestamp: September 25, 2020, 05:59:11 pm
content: Is this helpful?https://www.element.com/nucleus/2020/03/27/13/37/en-62368-standard-update-information

author: Northy
author_rank: Regular Contributor
timestamp: September 25, 2020, 08:54:55 pm
content: Hi Benta,Yes thanks, anything is helpful :-)I have the standard and understand the principal of being a more hazard assessed approach. What I'm trying to understand is how others ensure they design compliant products as they are designing them. Do people generate their own compliance matrix, list of design rules or something else?That would seem the more engineer type approach.Do these sorts of things exist out there?Thanks,G

author: coppercone2
author_rank: Super Contributor
timestamp: September 26, 2020, 05:42:26 pm
content: excel, post its, documents, note pads, etcwelcome to your first engineering job behind a desk. This task requires skilled use of office resources. You go by layers of abstraction to physical tests.
Designing Rigid-Flex PCBS - Page 1
Forum section: electronics / projects

author: ZGoode
author_rank: Frequent Contributor
timestamp: November 12, 2024, 02:58:50 pm
content: Does anyone have recommendations for designing rigid-flex PCBs with PCBWAY? I am working on a project that I am planning on using a 2 layer rigid-flex board, but am a little lost on how to do my stackup and export/name my gerber files. Up to this point I have only ever done standard rigid boards.
Designing Sallen-Key stages in S domain - Page 1
Forum section: electronics / projects

author: Dmeads
author_rank: Regular Contributor
timestamp: March 25, 2020, 06:36:10 am
content: Hello! Hope yall are healthy!Im a digital guy working on some DSP stuff, but Im building a high performance (relative to my knowlege) anti-aliasing filter using the S plane. Still learning the analog stuff, but its really cool!My filter is a 6 pole LP butterworth (at least I think it is butterworth, there is no stop/passband ripple).fc = 100KHz.I found my ampilification factors from trig using the s plane circle. ( all poles are evenly spaced on left side) They can be view on top next to the Bi-quad instance number.During simulation, i found some interesting results. After the first sallen key stage (first 2 poles), the -3db point was at 50 KHz, after the 2nd SK stage, 68 KHz, then after the third stage, 81 Khz.I know filters arent perfect but it seems I should get a better -3db point (closer to actual cuttof of 100 KHz).Does anyone know what I did wrong? Is it calculation error?Thanks.-Dom

author: Wimberleytech
author_rank: Super Contributor
timestamp: March 25, 2020, 11:38:27 am
content: Try R6 = 10KAlso, you will need an opamp with more GBW than the 741. Experiment with a generic opamp and dial in various GBW values.

author: Siwastaja
author_rank: Super Contributor
timestamp: March 25, 2020, 12:33:00 pm
content: Remember to simulate with component tolerances. I recommend you play around with Analog Filter Wizard (https://tools.analog.com/en/filterwizard/); it's easy to use and will draw the component tolerance envelope for you.The more complex the analog filter is, the more critical the component choices become, including opamp parameters and the tolerances of the passive components; sometimes even the parasitics (such as capacitive coupling).It may so happen that designing a simpler 2- or maybe 4-pole filter and just using an ADC with higher sample rate, to use a steeper filter in digital domain, ends up being not only more accurate, but possibly cheaper as well. The only function for the analog filter being satisfying the Nyquist criterion, you can move that further away by just sampling at higher freq, thus make the less steep transition region of a lower-pole filter acceptable. Then, in the digital domain, it's trivial to make an almost brick-wall filter, avoiding all component nonidealities.How important the stopband attenuation is for you? I.e., do you have actual strong, disruptive signals to stop, or is it just to prevent some low-level noise from aliasing?

author: Dmeads
author_rank: Regular Contributor
timestamp: March 25, 2020, 06:57:09 pm
content: stopband attenuation isnt that important, also i could probbly tolerate as low as -20db/dc rolloff too, i was just playing around

author: Dmeads
author_rank: Regular Contributor
timestamp: March 25, 2020, 08:46:27 pm
content: Quote from: Wimberleytech on March 25, 2020, 11:38:27 amyou're right, I got it all dialed in. thanks.
Designing soldering tutorial kit - Page 1
Forum section: electronics / projects

author: Rachie5272
author_rank: Regular Contributor
timestamp: March 11, 2020, 05:07:52 am
content: I've been teaching people some beginner's soldering skills, and I want to have a more formal class. For this I need to design a good kit, and I'd like some input on what people might find interesting.I'm thinking an LED clock might be a nice project. Blinking lights are always popular, but it also has a practical use, and would look good on a bookcase. Does anyone else have suggestions?I want to focus mostly on SMD, with a couple through hole parts for connectors. I'll try to stick to larger size components like 1206 and SOIC, and encourage people who would normally shy away from anything without holes. I'm contemplating having a sort of tiered construction with smaller components for extra functionality, which can be omitted if they're too difficult. At the same time, I don't want anyone to feel like they can't complete the challenge.

author: tooki
author_rank: Super Contributor
timestamp: March 11, 2020, 06:25:57 am
content: The vocational school I’m interning at right now uses these kits as their intro to soldering, even for non-technical students:Geekcreit® Large Size Rainbow Color Digital Tube DS3231 Clock DIY KitIMHO they’re definitely on the challenging side for absolute first-timers (in particular, the MCU, which is a QFP), but doable, at least if you have the right soldering tips available. Perhaps solder the MCU for them. The most common fault is simple shorts between LEDs, which manifest as blue or green missing from a segment. Easy enough to correct.Also, for a Chinese kit, it has very good instructions. It does have a few minor errors, so give it a careful review. (I can probably find out what the exact errors are if you need.)We are also just starting on a project of our own, namely an electronic hourglass using addressable LEDs and an Atmega328p running Arduino code, with a soft latch power circuit inspired by the AVR transistor tester circuit’s.

author: jeroen79
author_rank: Frequent Contributor
timestamp: March 11, 2020, 08:59:55 am
content: Quote from: tooki on March 11, 2020, 06:25:57 amThese would be a nice excuse to teach some rework as well.

author: tooki
author_rank: Super Contributor
timestamp: March 11, 2020, 11:39:07 am
content: Quote from: jeroen79 on March 11, 2020, 08:59:55 amYeah, it’s just an incorrect resistor value or something.
Designing sort of a differential probe - Page 1
Forum section: electronics / projects

author: tnt
author_rank: Regular Contributor
timestamp: April 05, 2011, 08:28:17 pm
content: Hi,I need to probe a differential signal (well actual 2) and I'd like not to use 4 channels of the scope just for this.Ideally I would have two good differential probes but those are rather expensive so I'm looking for a DIY solution.My signal is a IQ baseband signal, for ~ 10 mv up to 500 mV swing. It's mainly a 300 kHz signals but to get some details, having at least > 1MHz bandwidth would be nice. The signal is centered around 1.5 v, and since I'm already probing other single ended signals on that board, I don't care about isolation.So my idea was to use an instrumentation amplifier with a gain from 1 to 10.Unfortunately, finding one with a flat frequency response up to 1MHz isn't that easy. Currently the only one I found is the AD8250 and it looks OK. (albeit a bit expensive at ~15EUR).The remaining question is how to power it ?I'd like to have an input power range from 2.5v to 5.5v and from there I need to get something like -6 +6V .At first I was thinking of using a simple switcher like those in CCD bias generation (since in a single chip they have both boost and inverter), and follow that by two LDOs to 'filter it' further. But now I'm kind of worried that the inductors on those supply will generate EMI into my measurements. (The DUT would be connected to the 'probing' board with thin flying wires).So I was looking into charge pumps but haven't found a fitting one yet .. they're either doubler or inverters but from 2.5 to -7V there is more than double or invert ...Any suggestions ?Cheers,Sylvain

author: tnt
author_rank: Regular Contributor
timestamp: April 06, 2011, 01:52:54 pm
content: Yes, I know that it's not trivial but since I lift quite a few requirements of true differential probes (like complete isolation, wider bandwidth, higher voltage support), I tought off-the shelf part might be easier to find.The LT1194 looks ok, but not in stock. However I didn't think to look in the "high speed" category for a "difference" amplifier. Not exactly instrumentation but I guess sufficient for my application.For the power, I also think I could use the +- supply of the scope itself (via the "autoprobe" interface), but I'd rather not. I'd like to supply the power from the target board itself (which is powered via a 3.7v li-ion single cell)

author: Unknown
author_rank: Unknown
timestamp: April 06, 2011, 07:38:57 pm
content: Real differential probes often use a video line driver IC, and use only a limited part of the dynamic range to avoid slew rate/gain-bandwidth limitations. These should easily get you up to 100MHz. Matching the attenuators and other components to get a reasonable CMRR at that frequency is not so easy, though, but you might be OK at 1MHz with limited CMRR requirements (?).
Designing Startup Network for Flyback Controller - Page 1
Forum section: electronics / projects

author: Red_Micro
author_rank: Regular Contributor
timestamp: May 25, 2020, 06:07:54 pm
content: I'm trying to design a startup network for thisflyback controller, see the picture at the end. I want the controller to start within 10 ms at most. This is what I'm doing:Due to the wide input voltage, I'm connecting the startup network to a tapping point from the capacitors in series. This allows me to choose a lower Vds depletion MOSFET like this:CPC3980ZTR1) Would this cause some imbalance in the caps?Now, during startup a current flows from inputs caps C14 & C15 through the depletion MOSFET Q5 (normally on). This current will charge the Vcc capacitor C16. The gate of Q5 is connected in the middle of the resistor divider formed by R29 and R30. As the voltage over C16 increases, the gate voltage of Q5 becomes negative with respect to its source voltage. When threshold voltage of Q5 is achieved, it turns off.Resistors R29 & R30, and Zener diode D16 are dimensioned so that Vcc achieves the minimum value UVLO for the controller to start. From this point, controller will be fed by the auxiliary winding, and Q5 will stay off until the next start-up.According to the datasheet, the threshold voltage for Q5 has minimum and maximum levels of -3.1 and -1.4, respectively. The minimum Vcc voltage for the controller to start is UVLO = 21V, and the max Vcc is 35V. I will allow a max voltage of 27.5V for overvoltage protection. During startup, the voltage over resistor R29 is the voltage between gate and source of Q5.By setting R29 = 10KR29*i_R29 < 1.4V only if V_C16 > 19.5V --> i_R29 < 0.140 mA for V_C16 = 19.5VR29*i_R29 > 3.1V only if V_C16 < 27.5V --> i_R36 > 0.310 mA for V_C16 = 27.5VBy using a 20V Zener diode as D16, the first condition is met.For the second condition, the current through R29 can be calculated asI_R29 = (V_C16 + V_D17 – V_D16)/(R29+R30)R30 < (27.5 + 0.3 – 20)/(0.4mA) – 10KR30 < 15.2KR30 = 10K2) How do I calculate a proper value for C16? And the time this circuit will actually take to start the controller?
Designing step up converters - Page 1
Forum section: electronics / projects

author: Dajgoro
author_rank: Frequent Contributor
timestamp: May 24, 2017, 01:42:39 am
content: HiFor some recent projects I needed to raise the voltage from regular battery level voltages to voltages up to 50V for things like VFD displays, piezo buzzers, etc...Since I did not require a regulated voltage, but rather just something in the area, I did not use a proper step up ic but rather I tried just having a oscillator, either astable circuit or mcu pwm source to drive the switching.I would mostly rely on doing simulations in LT Spice and iterate on the design until I would get something that works well enough to be used.I have a general understanding of how such circuits operate and how can certain factors affect their performance,but I am looking for guidelines for designing such circuits in general so I have a better idea how to tune them to get more performance.

author: Dajgoro
author_rank: Frequent Contributor
timestamp: May 24, 2017, 01:57:46 am
content: Yes, I can get one, but my point is to try to learn how to do without one.

author: Someone
author_rank: Super Contributor
timestamp: May 24, 2017, 02:42:31 am
content: Quote from: Dajgoro on May 24, 2017, 01:57:46 amThe information is out there:https://www.maximintegrated.com/en/app-notes/index.mvp/id/2031You can make a practical/useful boost regulator with just 2 comparators, orone 555once you can design analog circuits.

author: Dajgoro
author_rank: Frequent Contributor
timestamp: May 24, 2017, 11:23:45 am
content: Thanks!
Designing the Portable Party Power Pack v.3.0 - Page 1
Forum section: electronics / projects

author: Twellmann
author_rank: Newbie
timestamp: December 08, 2010, 12:46:31 pm
content: Hi all,I'm currently planning my third version of the Portable Party Power Pack, a battery powered amplifier with built USB-charger for cellphones and iPods. The amplifier is based on the lovableta2020, and is powered by 8 D-cells. I've used the other systems for festivals, the beach and other parties with great results.This time around I have better access to a machine shop and a working electronics labOn the attached photo you can see the basic idea.I have a few questions, but not the time right now to put them in writing/images.I've started a thread on one of my questions, but I'm linking to this thread instead.https://www.eevblog.com/forum/index.php?topic=1927
Designing T/R Switch, need some help - Page 1
Forum section: electronics / projects

author: Nautrax
author_rank: Newbie
timestamp: February 19, 2016, 09:07:28 am
content: HeyI need some help finding ressurces I can use to get a better understanding about T/R Switching. I'm working on a school project where I have been tasked with designing a T/R Switch for a Sonar.I found some ressourses about this so far, but its mainly for high frequency and often buildt with PIN diodes. From what I understand PIN diodes are a poor choice at a lower frequency.The sonar is going to operate on 400 khz so any ressourses that gives explanation or examples close to that range whould be highly appreciated.

author: dmills
author_rank: Super Contributor
timestamp: February 19, 2016, 11:55:25 am
content: The standard approach for sonar applications is a pair of back to back Si diodes in series with the transducer with the RX pickoff across them (Transducer transmit bandwidth is small enough that the harmonics produced don't matter, look at the G/B curve), this relies upon the transformer magnetising inductance being reasonable.Sometimes you place the same thing in the matching transformer primary so that noise from the power amp does not interfere with the tiny received signal, depends on the nature of the driver (Often a simple H bridge in which case there is no point).You wont find a PIN diode with a long enough recombination time to make this work, and there is no need in any case.400KHz, so short range application? Imaging? Interferometric?I used to design sonar for a living.Regards, Dan.

author: Nautrax
author_rank: Newbie
timestamp: February 19, 2016, 05:23:38 pm
content: Thanks for the reply.You are right about the application, we are making a small side scan sonar.
Designing transformer for uc3842 offline flyback power supply - Page 1
Forum section: electronics / projects

author: Achu
author_rank: Contributor
timestamp: October 16, 2019, 04:54:21 pm
content: I need help on how to calculate turns in flyback transformer for the above mentioned power supply. Now I know about designing Half bridge, full bridge and forward converters but I am unable to figure out about flyback converters.I indent to build one out of scratch even though I know I can buy one. I think I'll use it as aux supply for the variable half bridge SMPS bench supply I'm currently working on.Here's a sample circuit although it seems to be crude and does not have an RCD snubber.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 16, 2019, 06:08:43 pm
content: Figure around 50% duty cycle in BCM, i.e., primary peak volts are double the DC supply (consider the output voltage if the primary winding were used as a boost converter).Flyback is more flexible than forward, so you have some freedom to choose this peak voltage. It can be higher or lower than the supply. Higher means more stress on the transistor (need higher Vds), higher primary duty and lower secondary duty. (Low duty is bad because it means all the input or output power is drawn during a relatively short time, making the RMS current in the filter capacitors that much higher.) Lower peak voltage means less stress (lower Vds rating), lower primary duty and higher secondary duty.Because of duty cycle, you probably don't want peak voltage below 1.5 Vin, or above 3 Vin.Because of Vds rating, a somewhat lower peak voltage is preferred, so we might aim for 1.5 to 2 Vin.If the input is 360V and the flyback is 240V above that, we get a peak of 600V, and would choose Vds >= 800V (a commonly available rating). For say 12V output, we need a ratio of 240/12 = 20:1.If you have the winding area, the primary should preferably be wound in a single layer over the secondary, or interleaved around the secondary (or the secondary around the primary, it doesn't matter). This keeps leakage inductance low. This is a priority for higher power supplies (>50W?), but not critical for smaller ones (5-20W?), and actually it swings the other way for low power ones (1W?) where capacitance instead dominates so a looser (multilayer?) winding is preferred. (The actual property being controlled for here is characteristic impedance, not just leakage inductance or capacitance but in fact the square-root of their ratio.)Tim
Designing with dual SIM (socket and eSIM) - Page 1
Forum section: electronics / projects

author: okw
author_rank: Frequent Contributor
timestamp: August 29, 2023, 11:19:18 am
content: I want to have both nano-SIM socket and eSIM (MFF2) to a nRF9160. Since they both will be parallel, I was thinking to break eSIM power (VCC pin 8 of MFF2), when a physical SIM is inserted using the CARD_DETECT on the SIM socket. It will never be hot-swapped (and rarely changed), and rebooting the modem when changed is no problem.Would this be a fail-safe method (given the socket doesn't malfunction). What is best practice?

author: Phoenix
author_rank: Frequent Contributor
timestamp: August 29, 2023, 11:43:23 am
content: How about a sim multiplexor ic like TXS02324

author: Scrts
author_rank: Frequent Contributor
timestamp: August 29, 2023, 12:01:05 pm
content: Maybe it's worth just putting it into a reset? I/Os should become hi-Z.

author: okw
author_rank: Frequent Contributor
timestamp: August 29, 2023, 12:38:49 pm
content: Quote from: Scrts on August 29, 2023, 12:01:05 pmI'm not sure if I understood. All signals (including reset) is in parallel, so reseting will reset both and what happens if a physical SIM and MFF2 is on the same "bus" at the same time?Or is this taken care of in the protocol, so they won't interfere, and I can chose preferred SIM/MFF2 in software?
Designing/ideas for test jigs - Page 1
Forum section: electronics / projects

author: logictom
author_rank: Unknown
timestamp: November 27, 2014, 11:14:12 pm
content: Are there any good resources available for designing/setting up test jigs?I'm looking for things like blogs were someone has gone through the process and included stuff like what worked best/what they'd do different, quick and dirty vs something more refined.Even photos of different jigs would probably be quite useful.

author: Charles Creations
author_rank: Contributor
timestamp: November 28, 2014, 12:51:42 am
content: I assume you have already looked at Dave's video on design for manufacturability:

author: logictom
author_rank: Unknown
timestamp: November 29, 2014, 08:35:30 am
content: I have but I think I will need to rewatch that one, thanks Charlie.I was after some examples of the test jigs themselves, what are best practices and what methods are usually used - no point reinventing the wheel if someone else has thought of better ideas

author: DTJ
author_rank: Super Contributor
timestamp: November 29, 2014, 12:39:10 pm
content: No resources as such. Depending on your board type the following may be useless.I' ex used a bare pcb the same a s the DUT.I fit it to a sheet of aluminium or similar with standoff a and a second set of standoffs with thread less extension for the DUT to slide onto.Fit spring loaded pogo pins to the bare board and wire those points off to whatever test circuit or instruments are needed. Works well for me on the low speed and analog boards I work with.To hold boards in place I place a small insulated weight on them if needed.
Desoldering machine made from old shopvac - Page 1
Forum section: electronics / projects

author: Ferroto
author_rank: Frequent Contributor
timestamp: November 14, 2019, 10:28:02 pm
content: I picked up a $10 mini shopvac at a yard sale and 3d printed an adapter to attach a standard solder sucker. It works fairly decently however I'm going to have to install a leaf switch and a relay to turn the vacuum on and off.

author: gibbled
author_rank: Regular Contributor
timestamp: November 14, 2019, 10:41:04 pm
content: Neat idea! watch out for overheating of the shopvac motor though. I believe they are cooled by the air flowing through them, which is now greatly reduced by the small orifice of the solder sucker. Adding a few holes to the hose upstream from the tip should allow more airflow.

author: ChristofferB
author_rank: Frequent Contributor
timestamp: November 15, 2019, 03:13:59 pm
content: Neat! You can get heated solder suckers as well, which would fit right on, but my experience with normal vacuum desoldering stations is that the tips oxidize and dissolve, so replaceable tips are a must.Maybe you should put in a bypass hole to keep the engine cool, that you could cover with a finger when you want full vacuum.--chris
Desoldering - Page 1
Forum section: electronics / projects

author: daniel123
author_rank: Regular Contributor
timestamp: May 01, 2016, 01:07:58 am
content: HiI was wondering if anyone has advice for desoldering very small smd components with nothing but a soldering iron. I have an unregulated ecg iron 20 watt and a hakko888d. and will i need a hot air gun if i try to take off surface mount ic's?Thanks daniel

author: tautech
author_rank: Super Contributor
timestamp: May 01, 2016, 01:14:45 am
content: Quote from: daniel123 on May 01, 2016, 01:07:58 amYes.Study this thread:https://www.eevblog.com/forum/projects/how-difficult-it-is-for-hobbyist-to-work-with-smd-packages/

author: KL27x
author_rank: Super Contributor
timestamp: May 01, 2016, 02:20:48 am
content: Depends on how big the package is and if you want the part intact.It is fairly trivial to remove smaller IC's by flooding the pins with solder and removing the part while it's hot.It is also totally possible to cut off the pins and then remove them one at a time. Or to melt the solder and lift the pins with a knife, one at a time.QuoteIf you're talking about VERY small passives and SOT parts and the like, you can easily use the solder blob method for a lot of these parts. Or a knife (K) tip can be helpful for the passives.

author: sleemanj
author_rank: Super Contributor
timestamp: May 01, 2016, 04:38:41 am
content: I highly recommend a hot air station if you work with SMD. Just a cheap Chinese one is fine (check it for safety though), $50 to $100 and you have a tool which will save you so much hassle and time when you want to remove/replace a part on a board.(I find) a hot air station is all but useless for actually assembling a board from scratch, use your iron for that, but for reworking, absolutely essential.

author: Skimask
author_rank: Super Contributor
timestamp: May 01, 2016, 04:56:30 am
content: Quote from: blueskull on May 01, 2016, 03:37:24 amChipQuik makes something like 20 different mixes. Sn/Bi is just one type.But, bloated price...Yes...How can the O/P afford desoldering equipment is he's hard up for free equipment?

author: Skimask
author_rank: Super Contributor
timestamp: May 01, 2016, 05:34:41 am
content: Quote from: evb149 on May 01, 2016, 05:28:36 amI don't.Made the mistake of buying a 50g container from Sparkfun before I figured out the stuff was seriously overpriced...as most of their stuff is.Or maybe that's the going rate for it. I don't know. Haven't looked lately. That was almost 2 years ago though. I haven't burned thru that 50g container yet. I store it in the bottom of the fridge, let it warm up to room temp for a couple hours before I use it, throw it back in the fridge when I'm done. Last fall, I mixed in about a dozen drops of liquid RMA flux after the paste seemed to not reflow so well. Works well enough after the addition though.