hybridfree/eevblog-posts huggingface dataset:
Help with identifying connector and cable. - Page 1
Forum section: electronics / beginners

author: Talesh
author_rank: Newbie
timestamp: December 07, 2017, 08:19:43 pm
content: Hi guys,For reference: I am incredibly new to electronics and bought a Hakko soldering iron for a minor project this year.The attached photo is of a cable that connects two halves of a split keyboard I just bought. My hope was that this cable would have been 4 wires or something which I would have been able to desolder it to extend the cable length. But instead I find this 20 wire cable connecting both halves with the connector on the end.So now I am thinking maybe this may be a standard type connector and a standard type of cable I may be able to find online instead of having to do a bunch of soldering with very tiny wires. Any thoughts on how to proceed? Maybe where to find that type of connector and a 20 strand cable in the 2 metre range?ThanksTalesh

author: Awesome14
author_rank: Regular Contributor
timestamp: December 08, 2017, 06:27:31 am
content: I personally wouldn't even try to find such a cable. You might be able to find the connectors and a 20-conductor cable. But it wouldn't be fun.

author: oldnewb
author_rank: Contributor
timestamp: December 08, 2017, 07:42:39 am
content: What Awesome14 said. You could search high and low before finding out the exact make and model of connector used in your keyboard. Furthermore, those sorts of connector families are often made for wire-to-board applications, only. It's likely there is no version of the receptacle that can be easily fitted to the end of a cable, which you'd need for an extension. You may get away with using crimp-on splices (see URL below), or there could be a lot of soldering practice in your future.https://www.digikey.com/product-detail/en/te-connectivity-amp-connectors/321026/A27461-ND/299225

author: Talesh
author_rank: Newbie
timestamp: December 08, 2017, 03:21:51 pm
content: OK assuming that I cannot find the connector, I'll have to cut/splice and extend the wires.So how would I go about determining if the signals running through these wires can survive an extension to 2metres?How do I determine what gauge wire I need if I were to extend them?I'd like my final job to be neat so where would I find 20 strand cables (in Canada)?Finally I own a cheap $25 multimeter and soldering system from a previous project which may be able to help me in this project.

author: oldnewb
author_rank: Contributor
timestamp: December 09, 2017, 05:24:28 am
content: Hard to say without knowing how the signals are being used. Can you post a few photos of the insides of the keyboard halves?With that many wires, it's likely to be carrying signals for a keyboard matrix. A 2m extension would probably work, if you're up for a lot of tedious soldering. I don't know the best places to shop in Canada. Any of the usual outlets (Digi-Key, Mouser, etc.) are a good place to start. Look for something like this 10', 24-conductor cable from Digi-Key:https://www.digikey.com/product-detail/en/3m/3600B-24-100SF/MB24S-10-ND/2764950(You only need 20 conductors, but it'll be a lot cheaper if you go with a more popular configuration.)
Help with identifying connector - Page 1
Forum section: electronics / beginners

author: StarFishPrime
author_rank: Contributor
timestamp: January 29, 2014, 05:59:20 pm
content: Hi folksI work teaching pre-university physics in the Uk and have students building a series of projects such as lightning detectors, earth field magnetometers etc. These will be mounted in metal enclusres and I want some high quality fitting to feed in/out analog data cables via screw in connectors such as that in the attached picture. can anyone tell me what the general name is for this type of connector or make recommendation as to other rugged and shielded types.cheersian robinsonstarfishprime.co.uk

author: Fabiusp98
author_rank: Contributor
timestamp: January 29, 2014, 07:21:45 pm
content: For signal you can try the usual oscilloscope coaxial cables, you can also use XLR audio connectors or vga like d-subminiature connectors.

author: fcb
author_rank: Super Contributor
timestamp: January 29, 2014, 07:25:36 pm
content: Looks like an industrial sensor connector, google M8 or M12 connector.

author: tornup
author_rank: Newbie
timestamp: January 29, 2014, 07:46:45 pm
content: a google search starting with "Panel Mount" is a good start.then usually the amount of pins....for example, i searched Google for "panel mount 4 pin connector"and come up with this:http://uk.rs-online.com/web/p/product/7406098/?grossPrice=Y&cm_mmc=UK%7CShopping-_-Google+PLA-_-Lumberg%7CDIN+Connectors-_-7406098&kpid=&istCompanyId=f7e7b05b-2daf-4c0e-8825-3633baf8113b&istItemId=xwilmiqra&istBid=tzit&gclid=CO6yyJiSpLwCFQjjwgodAngAuAhowever, XLR connectors are nice, and you can get a 5 pin one quite cheap too!google "5 pin xlr panel mount"Also the cable is usally for mic's and audio stuff, so is shielded quite nicely for sensor data!(should you decide you CBA to make your own cables! lol)Tom.

author: AndyC_772
author_rank: Super Contributor
timestamp: January 29, 2014, 07:47:07 pm
content: There's a good selection here:http://www.binder-connector.co.uk/en/products

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: January 30, 2014, 05:39:54 am
content: This looks like an M8 connector. In my experience, these do not take much abuse.Look at larger industrial M12 connectors. They are common in industry and are available with up to 8 or 9 pins as I recall. Turck is a major supplier but they are made by many companies. Pre-built cables are relatively cheap...less than $10.
Help with identifying SMD component with Marking Code AK205 - Page 1
Forum section: electronics / beginners

author: Carl1
author_rank: Newbie
timestamp: October 19, 2022, 08:09:39 am
content: Hello, I have tried various databases but am at a loss to identify AK205 .. I feel it could be an ESD component.Have attached a pic of the PCB with damaged AK205 that I need to replace.. would appreciate any assistance.Many thanks

author: MathWizard
author_rank: Super Contributor
timestamp: November 17, 2022, 06:00:44 pm
content: Whats the circuit from ??Looking at the circuit I think it's another buck converter regulator IC, pin 5 would be Vcc . Pin 6 is probably the Vout to the inductor, Pin 3 is sensing the output from the inductor, pin 2 is probably the path to the internal mosfet, which gets shorted to gnd when on. Even if all thats wrong, I've seen a lot of similar little 1 chip buck regulators circuits this year. And in all cases, the actual controller chips would be very interchangeable (if their operating frequency was about the same and adequate).The resistor divider on pin 3 is used internally to set the output voltage. And it's probably just 4.7k and 4.7k, or 10k, 10k.C278 is probably the compensation cap, that would be on the internal op-amp feedback circuitFind what that voltage rail is supposed to be or where it goes.Have a look at some other 6-pin buck regulators, they are all pretty similar, and many operate over a range, and the input voltage from that jack, and the divider would basically tell you what chip to swap in....if the pinout was exactly the same. If not, a different chip could be put on a proto-board, and just wired to the pads of the old chip. You might have to change a resistor too.https://www.google.com/search?q=6-pin+buck+regulator&tbm=isch&ved=2ahUKEwi6vKTu3bX7AhUwEmIAHYZjCg4Q2-cCegQIABAA&oq=6-pin+buck+regulator&gs_lcp=CgNpbWcQAzoECAAQQzoFCAAQgAQ6BggAEAUQHjoICAAQgAQQsQM6BAgAEB46BggAEAgQHlDfDljmSWC9TGgAcAB4AIABgAGIAckSkgEEMC4yMZgBAKABAaoBC2d3cy13aXotaW1nwAEB&sclient=img&ei=YW52Y_qHJrCkiLMPhsepcA&bih=1203&biw=1205&client=firefox-b-d

author: Carl1
author_rank: Newbie
timestamp: November 20, 2022, 06:26:27 pm
content: Thank you kindlymuch appreciated the research into my query.. you are correct.. it appears to be the same as what I understand to be FP6190 SOT23-6..
help with igbt driver working on dual rails - Page 1
Forum section: electronics / beginners

author: superwester
author_rank: Contributor
timestamp: February 24, 2018, 08:56:56 pm
content: Im trying to build my own vdf to power an induction motor.im going for an ir2110 (https://www.infineon.com/dgdl/ir2110.pdf?fileId=5546d462533600a4015355c80333167e) as half h bridge driver. for the supply im using 12 volts ac coming from a transformer going to a voltage doubler circuit to generate a positive and negative dc voltage (+-12v in relation to center tap) to generate the ac at different frequencies. the igbts will be two FGPF4536(http://pdf.datasheetcatalog.com/datasheet/fairchildsemiconductor/FGPF4536.pdf) that will work at 20 to 100 hz.this way i can connect one end of the motor to the virtual ground of the voltage doubler and i can alternate between a positive and negative voltage at the other end.the thing that's being a little bit tricky is to work with two voltage sources, and ultimately i want to use this with mains voltageattached in this post are: my first aproach that was to use the negative rail as common(for the ir2110), and the second aproach wich was using the center tap of the voltage doubler as common and just feeding the negative voltage to the low side igbt.my questions are the following:1) on the first option what may fail is the bootstrap circuit wich will have higher floating potential difference floating to power the high side mosfet, according to the datasheet this will be alright for the ir2110 but im worried about the igbt's gate-source maximum voltage (+-30v) if i want to use a higher voltage later, Will this be an isuue? or am i missing something?2) on the second aproach, im afraid that by connecting a negative voltage directly to the source of the igbt, like on the previous question, the max Vgs voltage will be surpased beacause gate will be around gnd and source at -V. can i discard this solution completely?3) maybe, according to my worries on the previous questions, is it better to use 2 single mosfet drivers to control each side?4) what are general security implementations with this kind of circuits?thanks in advance,Martin.PS: i think i used the nomenclature for mosfets instead of the one for igbt's. is it too bad?
Help with improving enclosure cooling - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: December 11, 2023, 02:07:32 am
content: Hi,I have a cabinet attached to the outside wall of my home, it contains two off-grid inverters. I wasn't involved with the setup its really far from ideal.It currently has two fans to create airflow:FMA1-08038WBHT12230vSeperate temperature dial controls whether the fan is on/off80mm 38mm5.5w31db4000rpm41cfmI'm thinking of replacing the fans with;Same dimensions230vPWMTemperature increase increases speed (programmable curve 30°-20% to 70°-100% kinda thing)At least 50% more cfm at highest speedQuieter than the old fan for the same RPMI'm familiar with PC cooling but I've no idea if I can get off-the-shelf 230V AC fans and a suitable controller that won't break the bank.After some more googling I don't think PWM for AC fans is a thing, it might have to use a PSU to switch to a DC fan.Thanks.Richard

author: u666sa
author_rank: Frequent Contributor
timestamp: December 11, 2023, 04:44:32 am
content: What's the difference between your fans and one of this?None! Indeed you can get two of these cheap. Under $10. Then a regular temperature controller from aliexpress and turn them on with a relay. For it to be quite it has to be 120 mm or above and 27 db or less, then screwed to cabinet through rubber grommet. If you have problem finding a relay, here is an idea. An equally cheap 7 day timer plug. Disassemble it, isolate turn on wire and common ground, two wires out that connect to your generic temperature controller.Bathroom fans and 7 day timer your best source will be local hardware store or an online hardware store which has free shipping. Temperature controller aliexpress is best.If I login to hardware store here, I can purchase each fan for $8 and a timer for $8. So total will be $25. Plus $3 for temp controller. Plus rubber for $2. Everything together is under $30.Though, think about mice and rats. I had washing machine outside, little thing crawled inside and shorted it.
Help with IMU design - Page 1
Forum section: electronics / beginners

author: danbr
author_rank: Contributor
timestamp: April 23, 2015, 02:50:18 pm
content: Hi everyone.This is my first post, and I am a mechanical engineering by schooling, but electronics has always been a hobby for me.I'm working on making an integrated solution for a bunch of sensors on one "hat" for a raspberry pi. I'm currently working off an opensource design from adafruit(https://learn.adafruit.com/system/assets/assets/000/012/538/original/sensors_10DOF.png?1385649061) but with some different sensors for my application. And yes, I know there are many standalone "boards" that do this, but this is a learning project for me.But not knowing much - other than the basics of circuit design, I would love if someone could take a look over my schematic and check my work?Links to datasheets:LSM303D - accel/magnetometerhttp://bit.ly/1Qo7DKLL3GD20H - 3 axis gryohttp://bit.ly/1byCZPgLPS25H - barometerhttp://bit.ly/1OKFDgVI am mostly curious about the power input smoothing/protection. All the designs I've seen work off 5v with a VR bringing it down to 3.3v with caps added. I decided to pull 3.3v from the pin header and just roll with that. Attached is my schematic in eagle and the datasheets for the 3 sensors.Thanks!
Help with input protection circuit and reverse polarity protection - Page 1
Forum section: electronics / beginners

author: teslinius
author_rank: Regular Contributor
timestamp: October 17, 2021, 09:17:20 pm
content: I am designing an electronic load rated for 150V 25A max, i completed most of the schematic the only thing i'm not sure about is input protection, i only placed a varistor for overvoltage protection, i checked a bit how other electronic loads are built and i noticed that they have some power resistors and film capacitors but i'm not sure what kinda circuit are they making, also do electronic loads usually have reverse polarity protection?, and if they do what kind of circuit it is because at high currents like this i would need a beefy mosfet for protection which increases the cost

author: drdm
author_rank: Contributor
timestamp: October 19, 2021, 08:47:20 am
content: https://circuitdigest.com/sites/default/files/circuitdiagram/Reverse-Polarity-Protection-circuit-diagram-Using-P-Channel-MOSFET.jpgThis is the standard circuit for a MOSFET RPP.And yes, you'll need a fairly big transistor, but that's the cost of doing business.
Help with isolated grounds - Page 1
Forum section: electronics / beginners

author: kmike
author_rank: Regular Contributor
timestamp: August 18, 2023, 05:34:56 am
content: Dear members,I am currently designing a board with isolated 24V digital inputs and +-10V analog inputs. The board would have several input blocks wich are isolated from each other and the microcontroller, but should still have a PE (earth) connection.The current design is attached: 24V_DI and GND_DI are the power input and refernce for the digital inputs, 24V_DI2 is the power supply for the digital isolator chips.As never having to design such a circuit, I have some questions:1, is the attached way the proper way to do this?2, should C3 be a ceramic or an electrolythic cap?3, should I tie the grounds together with some high value resistors?Thanks in advance!

author: Terry Bites
author_rank: Super Contributor
timestamp: August 18, 2023, 04:25:16 pm
content: Right off the bat.If both sides of the isolation barrier are connected to a common PE, then you've circumvented the isolation barrier.Connecting individual input blocks to PE also defeats the inter isolation of these blocks.You have to choose to ground one side of the barrier or the other or neither. Most rationaly at the micro sideIt would be helpful if you drew a block diagram of your systems.Tying the grounds together though high value resistors will might equalise static potentials, but it renders PE pointless, there will be no protection. You might think about connecting various grounds together via bidirectional TVSs to PE. The isogrounds only connect to PE during a fault condition, else just a very small leakage current flows between blocks and PE. The TVS has to be able to comfortably handle the full fault current until the line breaker or fuse pops. Vf drops won't matter in fault condition. A 6V device would keep all the grounds within 6V of PE for the duration of an event.You're aiming at multiport isolation including separate iso power supplies for each and every block except the micro? A lot of DC-DC converters then.What risks does your system need to mitigate against. Why is isolation needed? Why cant the inputs be differential pairs?Why do the inputs need to be tied to PE?What does C4 do? The Zener needs to be replaced with a TVS, it will clamp over-voltages much faster than a Zener.I played with some AMC1333M10s from Texas Inst recently. Powered from NXE1S0305MC-R7s. Easy. Next step, sort out digital filtering. Harder.If I were more of a digital man I'd be looking at a ready rolled solution, ADE1201s @$10 a channel.
Help with Kelvin-Source-Pin in Class-E Amplifier - Page 1
Forum section: electronics / beginners

author: paulscout550
author_rank: Newbie
timestamp: May 21, 2025, 08:02:09 pm
content: Hello everyone,I'm currently building a Class-E amplifier for one of those plasma toroid projects some of you might have seen on YouTube. I'm planning to use a SiC MOSFET, specifically the IMDQ75R090M1H, which looked promising based on its datasheet. In my LTspice simulation, the design performs well, I get about 90 Wpp from a single MOSFET (I'm using two in parallel). So far, so good. Now here's where I'm stuck: How should I handle the Kelvin source pin in the real PCB layout?From what I understand, the Kelvin-Source-Pin is meant to be connected to the decoupled ground reference of the MOSFET driver, so that high current flowing through the main source doesn't go through the Kelvin-Source-Pin and destroy the Mosfet.However, my design does not use a gate driver IC. Instead, I'm biasing the gate using a simple zener voltage reference. In my LTspice model, I just tied the Kelvin-Source-Pin to GND, and it worked fine there.But when designing my PCB, can I leave it unconnectet? Or would the strong EMF cause problems if it's left floating? Would it make sense to connect it trough a resistor to GND as a sort of pulldown to give it a potential?I'm a bit unsure if there is a good solution for this, or if i should just keep searching for a different mosfet without such a pin.Thanks in advance for any advice!

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: May 28, 2025, 07:49:53 am
content: Connect the Kelvin Source Pin to the local gate driver reference. In your case, the ground reference of the gate bias network (formed by Zener D1, RV1, R5, R6).Do not leave it floating. If left unconnected, it can act as an antenna and pick up noise.

author: mtwieg
author_rank: Frequent Contributor
timestamp: May 28, 2025, 01:18:18 pm
content: Since in your schematic the "driver" is coupled directly from the output, there's no sense in trying to pretend the gate drive has a separate GND. So I would just tie all GNDs together. Layout should put Q1, Q2, and C4 as close together as possible.If you coupled the output back with transformers instead (one per FET), then perhaps treating the GNDs separately might be justified.
Help with LD1117V33 linear regulator - Page 1
Forum section: electronics / beginners

author: bdew
author_rank: Newbie
timestamp: June 30, 2023, 10:51:50 am
content: First post on the forums, and pretty new to electronics in general - so please bear with me if i'm doing something stupid.I've bought someLD1117V33regulators off aliexpress to power an esp32 project i'm working on.I've wired it like this on a breadboard to check that it's actually working, just following the datasheet. The caps are both electrolytic and the "load" for the test was just a resistor.When plugged in the regulator drew ~1.8A from the +5 input and was rapidly heating up, the output was jumping around 1V instead of 3.3V (though i didn't have much time to probe around - had to unplug it before it melted everything)I checked my connections and nothing seems to be shorted. Tried with a few different parts from the same order in case one was defective (i have a pack of 10) but they do the same thing.At this point i don't know if i'm missing something obvious or was just sent junk from china. Any help please?

author: wraper
author_rank: Unknown
timestamp: June 30, 2023, 11:00:47 am
content: If it's indeed wired correctly, most likely you received fake parts. Try wiring it as 78xx and see what happens, maybe counterfeiters fucked up by relabeling wrong vreg IC.

author: bdew
author_rank: Newbie
timestamp: June 30, 2023, 11:59:33 am
content: Bingo! I rewired it so that the middle pin is ground and they are working... kinda, the draw is about 40mA and it outputs ~3.9V across that resistor.So i guess it's as you said, they took some different regulator and sold them with the wrong label.Thanks for the help.

author: wraper
author_rank: Unknown
timestamp: June 30, 2023, 12:13:38 pm
content: Quote from: bdew on June 30, 2023, 11:59:33 amIf it's 78xx rated for more than 3.3V, you could increase input voltage and see if it starts to regulate output voltage, for example to 5V. Or it could be not vreg at all but some sort of transistor.
Help with learning SI, PI - Page 1
Forum section: electronics / beginners

author: romhunter
author_rank: Regular Contributor
timestamp: July 23, 2020, 05:37:31 pm
content: I have no experience with signal integrity, power integrity and all the gitz... Can someone point me in the right direction and show me what to learn? And maybe some books to read? Simulation software?I would probably use it to do works like PCB layout, IC package verification, etc....Any help would be deeply appreciate. Thanks

author: Benta
author_rank: Super Contributor
timestamp: July 23, 2020, 06:54:28 pm
content: Here's a very good book:https://www.tiffe.de/Robotron/Bausteinuebersicht/MECL/HB205-D.pdfPay attention to chapters 3, 4 and 7.Cheers.

author: romhunter
author_rank: Regular Contributor
timestamp: July 25, 2020, 11:57:33 am
content: Quote from: Benta on July 23, 2020, 06:54:28 pmThank you, I'll come back to this topic once I get enough information from this book.

author: Feynman
author_rank: Regular Contributor
timestamp: July 25, 2020, 01:48:17 pm
content: "Signal and Power Integrity - Simplified" by Eric Bogatin is an excellent book on this topic.
Help with led driver - Page 1
Forum section: electronics / beginners

author: iceisfun
author_rank: Regular Contributor
timestamp: October 12, 2013, 07:06:55 pm
content: I have some 7 segment common anode 12 vdc LED segments I am trying to drive with a Max7219 and a PIC32 and I'm having trouble with the way these 7 segment displays work.I've got some common cathode normal 7 segment displays that I have working great in my example breadboard.Can someone give me some direction on driving these monsters?

author: mariush
author_rank: Super Contributor
timestamp: October 12, 2013, 07:53:01 pm
content: Max 7219 is a common cathode driver ... it's kinda hard and pointless to use it with common anode led segments.You can use something like ULN2003A (7 darlington array) or ULN2803A (8 darlington array) which enables you to light up individual segments... like in this picture here:You enable power to a particular number in the seven segment display by energizing the npn transistor npn transistor (or whatever you want, mosfet etc), then light up the segments you want by sending power to the base of individual darlington elements in the uln2803a set. When the darlington element is active, it passes electricity to ground, so it completes the circuit making electricity flow through the led segments. If you want to reduce the number of pins, you can add a simple shift register IC in the front of the uln2803A.

author: iceisfun
author_rank: Regular Contributor
timestamp: October 13, 2013, 06:00:02 am
content: Ok I have this working now, thanksI've used these to drive DPSS TTL laser to ground before, should have thought of these

author: geraldjhg
author_rank: Regular Contributor
timestamp: October 14, 2013, 01:29:27 pm
content: hinot easy with current hog displaysfor newer displays (less thn 5ma per seg)drive directly from mcu and use a uln 2003as digit sinksaludos

author: iceisfun
author_rank: Regular Contributor
timestamp: October 19, 2013, 07:45:26 pm
content: I got it working with the MAX7219, ULN2803 and a Hex Inverter
Help with lm386 - Page 1
Forum section: electronics / beginners

author: nobody
author_rank: Newbie
timestamp: January 29, 2013, 05:48:43 pm
content: how could i turn off lm386 when i plugged headphones and lm386 on when headphones not plugged . im using this circuit

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: January 29, 2013, 08:20:26 pm
content: You could connect a switch between any ground of positive voltage in the circuit or just between pin 4 and 2 ( 4-------. / .----2 )

author: nobody
author_rank: Newbie
timestamp: January 30, 2013, 08:37:32 am
content: But what kind of switch that would turn on when headphones not plugged and turn off when headphones plugged

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: January 30, 2013, 02:36:10 pm
content: That i cant answer.You could use a pressure switch or just a microcontroller.

author: SeanB
author_rank: Super Contributor
timestamp: January 30, 2013, 03:59:58 pm
content: Standard headphone sockets are available with a built in switch to provide a closed contact when headphones are inserted.
Help with magnetic switch sense range  - Page 1
Forum section: electronics / beginners

author: Jwillis
author_rank: Super Contributor
timestamp: November 26, 2018, 04:20:33 am
content: Before someone says "buy a new fan"I already did , this is more for curiosity than cost.I burned out a 120mm computer fan by over voltage.So as usual I decided to take it apart to see how it worked.I checked the 4 coils on the armature and they check good.The only other piece in the circuit is a magnetic sensor A1421 which is obsolete.This is the part I suspect is faulty.Now ,as I understand, the sensor will trip and release as the poles of the cylindrical magnet (S-N-S-N) pass by it which changes the polarity of the armature.Would that be an accurate analysis ?The only replacement I can find is A1422LK-T but the sensor range is different.https://www.digikey.ca/short/jvdv2jas you can see in the link. And don't seem to match the data sheetThe data sheet shows units in Gauss but the sensing range on comparison chart is describe in milliTeslas ..Threw me off a bit but figured it out eventually. 1 Gauss = .0001 Tesla, or 1 Tesla = 10,000 Gauss.Both seem to have the same Operate Point (15.0G)but different Release Point A1421LK Is typ 0G and the A1422LK-T is typ -15GAnyway would that be a problem if I decide to replace the sensor or should I just consider the peak to peak differential of 50G for both and not worry?
Help with Marginal IC Power-on Issue - Page 1
Forum section: electronics / beginners

author: jayalt
author_rank: Contributor
timestamp: February 09, 2023, 12:30:34 am
content: Hi all. Hope to get some opinions and suggestions on what to look at here.Long story short- I am having marginal power-on issues on an IC. Issues arose after I changed all the power components on my PCB including DC-DC regulators, load switches, and LDOs. This was out of necessity due to supply chain concern. I have two voltage rails going into this particular IC- an IO 1.8V, and an analog / VDD core 0.9V. When the device boots into this failed state- it does not run any code, and does not respond to a reset pulse. I need to power cycle in order for the chip to come back. Certain units are much worse than others. I can tell it has failed within a few ms after power up.The IC I am using does not have any specified power on sequence, no errata, and very limited support. There is no power rail sequencing defined, or maximum slew rate times published. I am basically working in the dark, and I cannot just switch vendors- so I am hoping that some experts might understand what is happening at the lower, internal level, and help me root cause this.My main observations so far:1. My rise times are significantly slower with updated power components. About 2.5ms for the 1.8V and 700uS for the 0.9V. Previously they were 600us and 30us respectively.2. I have tried a bunch of different power sequences with no luck. I am still waiting on support from supplier on the correct sequence but it has been weeks.3. I have been able to "fix" the issue with the following observation: if I disable power before my load switch has a chance to pull down the 1.8V rail completely, it leaves some residual voltage that drains slowly. If I power on before the 1.8V rail has a chance to completely discharge, then I can turn on the IC just fine. Maybe issue relates to my load switch?I'm having trouble understanding what is going on in observation 3? I haven't necessarily made the rise time any shorter - when I enable the load switch at power on with a small amount of voltage already existing at its output, I see the rail start to decrease a bit prior to rising - so the total rise time remains the same. Even residual voltage as low as 100mV on the 1V8 seem to work. I thought this might point to an inrush issue- so I removed some capacitance on the rail hoping to rectify it but didn't see any change. Any ideas?

author: thm_w
author_rank: Super Contributor
timestamp: February 09, 2023, 12:53:27 am
content: Schematic?Part number of the IC?
Help with Microchip Datasheet - Page 1
Forum section: electronics / beginners

author: Luchik
author_rank: Newbie
timestamp: August 30, 2016, 09:53:34 am
content: I am trying to understand the VSS and VDD pins connection in this Microchip datasheet:http://ww1.microchip.com/downloads/en/DeviceDoc/40001825A.pdfI am using44-QFN Package, so i found the pin allocation map for this package on Page 7:according to this picture, VDD are pins: 7,8,29,28; and VSS are: 6, 30, 31.I also found this pin allocation table on page 13:Pins 7 and 29 are not shown in this table!can I trust the allocation map to be true with both pins (7,29) being VDD?

author: amyk
author_rank: Super Contributor
timestamp: August 30, 2016, 10:31:11 am
content: That's apreliminarydatasheet... some errors are to be expected. But the fact that two packages with the same number of pins have a mostly the same but slightly different pinout is a bigI'd choose a more mature product unless you have a compelling reason to use it. This one is far too new.

author: EEVblog
author_rank: Unknown
timestamp: August 30, 2016, 10:35:30 am
content: I'd trust the pinout diagram over the table.As mentioned, yeas, a preliminary datasheet, bound to be some copy'n'paste errors. Report it.

author: stj
author_rank: Super Contributor
timestamp: August 30, 2016, 11:11:40 am
content: trust neither,email microchip and point out the error - get them to clarify it.

author: Kjelt
author_rank: Super Contributor
timestamp: August 30, 2016, 12:08:19 pm
content: Mistake has been in their datasheet since 2014:http://www.mouser.com/pdfdocs/40001768A.pdf

author: Kjelt
author_rank: Super Contributor
timestamp: August 30, 2016, 12:10:54 pm
content: If you have the chip measure the ohms resistance between the Vdd pins and the Vss pins , they should be close to zero ohms, that would give some confidence.
Help with modeling BA728 op amp in LTspice - Page 1
Forum section: electronics / beginners

author: jj5
author_rank: Unknown
timestamp: May 22, 2024, 06:09:13 am
content: Hi there. I am trying to model aBA728op amp in LTspice. The problem is that there are 730 op amps to choose from, and a BA728 isn't one of them. Some op amps which look like maybe good candidates are:opamp.asyopamp2.asyUniversalOpAmp.asyUniversalOpAmp1.asyUniversalOpAmp2.asyUniversalOpAmp3.asyUniversalOpAmp3a.asyUniversalOpAmp3b.asyUniversalOpAmp4.asyCan someone make a suggestion?

author: magic
author_rank: Super Contributor
timestamp: May 22, 2024, 08:36:42 am
content: LTspice built-in models are mostly limited to LT's (and now AD's) own chips.LTspice can also run many universal SPICE models which are sometimes released by manufacturers. So you may want to check if there is a BA728 model available from ROHM.If not, look up instructions how to configure the various "universal opamp" models in LTspice. They differ in how complex they are and how many parameters can be modeled, pick something depending on your needs.The chip itself appears to be very similar to the common LM358, but with a class AB output stage.

author: Zero999
author_rank: Super Contributor
timestamp: May 22, 2024, 09:55:25 pm
content: What's the BA728 doing?You need to consider the important parts of the model:To name a few:Gain bandwidth product.Slew-rate.Output voltage limit.Open-loop gain.Phase margin.Input impedance.I would go for UniversalOpAmp2.asy.I've looked at the data sheet and this is what I would do. I've not modelled the noise, which would require some guesswork.

author: jj5
author_rank: Unknown
timestamp: May 23, 2024, 02:54:44 am
content: Quote from: Zero999 on May 22, 2024, 09:55:25 pmI am buildingthis.

author: magic
author_rank: Super Contributor
timestamp: May 23, 2024, 07:25:37 am
content: If you just want to see how this circuit works, any ideal opamp model would do.Or you could try LT1013, which is another "improved LM358", available in LTspice.

author: Zero999
author_rank: Super Contributor
timestamp: May 24, 2024, 09:44:41 pm
content: It's not that important.For completeness, here's National Semiconductor's LM358 model, entered into LTSpice.
Help with modeling multivibrators in LTspice - Page 1
Forum section: electronics / beginners

author: jj5
author_rank: Unknown
timestamp: May 13, 2024, 12:09:22 am
content: Hi there. I wonder if someone can help me, I am quite lost.What I am trying to do is model a system of two multivibrators in LTspice. On the output I am expecting to see an audio frequency driving a piezoelectric buzzer, but the simulation just seems to show a constant voltage of 9V.I wonder, can anyone explain what is wrong with my model? Following is a screenshot and the LTspice file is availablehere.

author: ledtester
author_rank: Super Contributor
timestamp: May 13, 2024, 02:07:19 am
content: I first just tried getting the two-transistor astable multivibrator to work in ltspice and here's what I had to do:1. Use a real transistor model (e.g. 2n2222) instead of the generic one2. Specify an initial condition on one of the caps3. Add the "uic" option to the transient analysis directive.#2 disrupts the symmetry in the circuit so that it will start to oscillate.To set the initial voltage on a cap see this post:https://www.eevblog.com/forum/beginners/ltspice-what-does-ic-v(c1)10-actually-do/msg5497798/#msg5497798or you can set the initial voltage of a node on one side of the cap using the.IC V(...)=...directive.Another way to disrupt the symmetry is to make one of the cap values slightly different from the other.Note that the .asc file attached below is flawed in that it attempts to set the initial cap voltage using.IC V(C1)=...which seems to be quietly ignored by ltspice.Quote from: jj5 on May 13, 2024, 12:09:22 amIt's better to upload the asc file as part of your post.

author: MathWizard
author_rank: Super Contributor
timestamp: May 13, 2024, 02:21:59 am
content: I'll usually start the external sources at 0, if some circuit won't osc, but I'll have to remember to try setting some cap voltage or inductor current, if that doesn't work.

author: jj5
author_rank: Unknown
timestamp: May 13, 2024, 03:22:56 am
content: I got it working! Thanks!This is the first time I have successfully conducted a non-trivial SPICE simulation, so for me this is milestone.I have attached a screenshot and my .asc file.Thanks again!

author: ledtester
author_rank: Super Contributor
timestamp: May 13, 2024, 11:54:24 pm
content: As for what you should use for the .IC directive, you might want to following along these discussions:https://www.eevblog.com/forum/beginners/having-trouble-simulating-two-multivibrators-in-ltspice/https://www.eevblog.com/forum/beginners/ltspice-what-does-ic-v(c1)10-actually-do/

author: jj5
author_rank: Unknown
timestamp: May 14, 2024, 03:26:39 am
content: Excellent. Thanks again! For the record I made a video about this over here:
Help with modifying a Li-Po charging circuit. - Page 1
Forum section: electronics / beginners

author: WesBur13
author_rank: Newbie
timestamp: January 06, 2017, 04:13:35 am
content: So I have a single cell lithium polymer charger called the Hitec x4. The thing works like a dream and charges at up to 1 watt, but only does Li-Po. I am looking to switching to lithium high voltage batteries. The only difference charging wise is Li-Po batteries charge to 4.20v and Li-HV charge to 4.35v. There are no Li-HV chargers that work like the Hitec x4.So here is the real question, could I possibly use resistors to trick the charger into thinking 4.35v = 4.20v? I would never get close to the 1 watt limit, but would I be able to charge the battery using the voltage divider?Thanks all for reading!

author: vealmike
author_rank: Regular Contributor
timestamp: January 06, 2017, 08:56:39 am
content: No, you won't be able to use resistors to trick your charger.There is nothing wrong with charging a Li-ion to a lower voltage than it's maximum fully charged voltage. You won't loose much capacity by terminating charge .15V early. You'll also extend the life of the cell, especially if the cell is left fully charged for long periods.You need to check a few things to see if your charger is compatible with your cell.1/ Trickle charge current for a fully discharged cell. Charger must be =< Cell maximum.2/ Charger Change over point from trickle charge to constant current. Charger change over V must be >= cell requirement.3/ Charger constant current must be =< Cell maximum charge current.4/ Charger termination voltage must be <= Cell maximum voltage.
Help with momentary to latching array - Page 1
Forum section: electronics / beginners

author: hydrolisk1792
author_rank: Contributor
timestamp: December 08, 2018, 06:47:58 am
content: I have attempted to make a 16 button momentary to latching array with 8 556 timers. When I power up the board all is well, but when I go to trigger one of the timers, all of the outputs go high. Also when I go to turn one of them back off, the respective one goes off, however when I trigger a different one, the previous one (s) turn back on...Is there a better solution out there for this kind of thing? My control panel is wired as all buttons are commoned together and one wire from each button is the trigger wires.

author: Ian.M
author_rank: Super Contributor
timestamp: December 08, 2018, 08:12:21 am
content: My first reaction to that probelm would be to use an Arduino (or other 8 bit MCU) rather than effectively 16x 555 timers, even though the Arduino would need extra transistors to drive the relay coils, and a resistor ladder to put multiple buttons on each of the few remaining input pins.However, you've madea start with the 8x 556 chips, so to give us a chance to figure out what's going wrong, we need to see the schematic, + good photos of the project - an overall view so we can see the general layout and what's hooked up where, and a closeup of each sde of the circuit board.I suspect that your decoupling or layout is inadequate so when one timer pulls a current spike as it switches, its glitching all the others. However that's pure speculation until we've seen the schematic and photos.

author: Zero999
author_rank: Super Contributor
timestamp: December 09, 2018, 12:15:03 am
content: Yes, it's probably bad layout and decoupling.There are also plenty of alternatives to 555 timers. The first thing you could try is replacing them with the '7556. They're less sensitive to poor decoupling and have the same pin-out as the '556, there's no need to change the rest of the circuit.
Help with mpasm - Page 1
Forum section: electronics / beginners

author: Dule
author_rank: Newbie
timestamp: October 25, 2017, 07:21:17 pm
content: Hi there,I am trying to teach myself mpasm so I wrote a small program that was supposed to spin stepper motor one revolution in alternate directions.I am using pololu breakout board for A4988 driverHowever, my program just drives stepper non-stop in one direction. For some reason, it appears to be stuck in first loop and I can't figure out why.I would really appreciate if anybody could point out mistake to me as I have been stuck with this for the past few days without success.Thankslist p=10F200 ; list directive to define processor#include <p10F200.inc> ; processor specific variable definitions__CONFIG _MCLRE_ON & _CP_OFF & _WDT_OFF; '__CONFIG' directive is used to embed configuration word within .asm file.; The lables following the directive are located in the respective .inc file.; See respective data sheet for additional information on configuration word.UDATAdc1 res 1dc2 res 1;**********************************************************************RCCAL CODE 0x0FF ; processor reset vectorres 1; Internal RC calibration value is placed at location 0xFF by Microchip; as a movlw k, where the k is a literal value.RESET CODE 0x000movwf OSCCAL ; update register with factory cal valuestartmovlw b'11111100' ; Set GP1 output (pulse) andtris GPIO ; Set GP0 output (direction)main_loopmovlw b'00000001' ; Set direction to 1movwf GPIOmovlw .200movwf dc2loop_1bsf GPIO,1 ;Set GP1 highcall delay ; 1 ms delaybcf GPIO,1 ; Set GP1 Lowcall delay ; 1 ms delaydecfsz dc2,fgoto loop_1movlw b'00000000' ;Set direction 0movwf GPIOmovlw .200 ; 200 x 1.8 degree =360 degreemovwf dc2 ; One full rotation of stepperloop_2bsf GPIO,1 ;Set GP1 highcall delay ; 1 ms delaybcf GPIO,1 ;Set GP1 lowcall delay ; 1 ms delaydecfsz dc2,fgoto loop_2goto main_loopSUBS CODEdelay ; 1ms delayclrf dc1dly_1nopdecfsz dc1,fgoto dly_1END ; directive 'end of program'

author: StillTrying
author_rank: Super Contributor
timestamp: October 25, 2017, 08:24:35 pm
content: Well there's no return at the end of "delay".

author: Dule
author_rank: Newbie
timestamp: October 25, 2017, 09:54:06 pm
content: Thank you!!! problem solved
Help with multimeter. - Page 1
Forum section: electronics / beginners

author: lastdeath
author_rank: Contributor
timestamp: December 15, 2012, 04:23:44 am
content: Hi, i wanna buy a multimeter, and i wanna to know what multimeter i buy...im looking the extech ex403 and the extech ex505... which one is better?http://www.ebay.com/itm/EXTECH-TK430-Electrical-Test-Kit-w-EX430-DMM-MA200-/400362578807?pt=LH_DefaultDomain_0&hash=item5d37782377http://www.ebay.com/itm/Extech-EX505-Kit-Heavy-Duty-Multimeter-AC-Volt-Detector-Kit-w-Test-Lead-Kit-/200863229171?pt=LH_DefaultDomain_0&hash=item2ec461a4f3or has any better with the price up to $ 130?

author: retiredcaps
author_rank: Super Contributor
timestamp: December 15, 2012, 09:59:24 am
content: Quote from: lastdeath on December 15, 2012, 04:23:44 amAre you based in the USA?What are your requirements? For example, do you need to measure capacitors, uA current, True RMS, etc?
Help with my uCurrent - Page 1
Forum section: electronics / beginners

author: apoapoapoapo
author_rank: Newbie
timestamp: December 22, 2014, 11:11:44 pm
content: hi, I've just started using my uCurrent. The version is Rev 5.Circuit I am using is a simple 3V CR2032 with a 15k resistor.The 3v battery measures 2.96v , and measuring the circuit with the DMM I get 0.196 mA current, which is good.My cheap DMM have display up to 199.9 and therefore my mV range will read up to 200mV.However, when I use my uCurrent (Batt OK light is on) I have the following issues:1) in the mA and uA range with nothing connected to the current input, my DMM in mV range reads -2.4 . In the nA range it reads 0.2) with uCurrent in mA range, I connect the circuit with 3v battery and 15 k resistor in series to theuCurrent current input. Dmm reads -25.8 , which is nothing like the 0.197mA measured with DMM alone.am I using this device incorrectly ? please advice.I have also tried several new cr2032 batteries, they all yield the same result.

author: electr_peter
author_rank: Unknown
timestamp: December 23, 2014, 09:39:45 pm
content: Hi, it sounds like there could be some issues with your circuit or measuring technique. Could you describe how exactly do you connect your circuit to uCurrent? Picture or schematic would do. What DMM are you using? How do you connect DMM to uCurrent?To use uCurrent with 3V battery + 15kOhm resistor connect battery and resistor in series with uCurrent current inputs, connect your DMM across uCurrent voltage output and turn on uCurrent in uA mode (you mentioned mA mode - it should be uA mode).uCurrent output is in low mV range, not every DMM is capable of measuring so low accurately.

author: apoapoapoapo
author_rank: Newbie
timestamp: December 23, 2014, 10:07:31 pm
content: hi, thanks. it works now. (Problem with my wiring)

author: electr_peter
author_rank: Unknown
timestamp: December 23, 2014, 10:19:15 pm
content: Quote from: apoapoapoapo on December 23, 2014, 10:07:31 pmNo problem, glad it works for you.
Help with my undervoltage shutdown circuit - Page 1
Forum section: electronics / beginners

author: prosper
author_rank: Regular Contributor
timestamp: October 18, 2022, 03:54:39 am
content: I've designed an undervoltage shutdown circuit. I'd like some tips on:decreasing current consumption, and(ideally) a way to eliminate the startup switch - (or, at least, to start the circuit in 'on' state when the battery is connected.)anything else I've overlooked, or should consider?My design goals:Use jellybean parts that I have on handMinimize quiescent currentZero (or, <10's of uA) level of current consumption when in shutdownShutdown is triggered when Vbatt is < ~2.8V (anything from 2.75 - 3.1V is acceptable)Don't care whether it's high or low-sideTolerates up to 5.5V input (realistically, 4.4V is fine)My voltage reference requires 100uAExpected Iout is <250mAI haven't mathed out the values of R4/R6/Rhyst yet. I believe they are in the correct order of magnitude, but I need to dial in the exact values, bearing the current requirement for U3 in mind.A major current consumer is the reference, which needs 100uA (max). Perhaps I could use a zener or couple si- diodes in its place at a smaller current, although I believe that would be really temperature sensitive. Are there any other options or configurations (short of a specialty part) that I could use as a reference? I don't need a great precision.R6/C1 is intended to ensure the op amp inputs are always less than it's supply, and to give it enough time to fully turn Q2 off when the battery voltage drops below threshold.

author: ledtester
author_rank: Super Contributor
timestamp: October 18, 2022, 04:42:48 am
content: QuoteIt seems that you would want to have the LM358's V+ and C1 to tap into the positive supply to the right of R6. Is that right?

author: prosper
author_rank: Regular Contributor
timestamp: October 18, 2022, 05:01:55 am
content: Sure, but then the capacitor would just discharge through whatever load is connected, which might not give the ic enough time to shut the fet off hard, before all power is losg