hybridfree/eevblog-posts huggingface dataset:
Trouble identifying pinout - Page 1
Forum section: electronics / beginners

author: abqa
author_rank: Newbie
timestamp: April 02, 2019, 04:40:53 am
content: I have a air conditioner that has a header on the mainboard that various optional (expensive) addon communications modules can connect into eg wifiI am wanting to see if I can connect to this port and control it over serial or similar once I determine what protocol it is using. RS232?, RS485?I have been trying to determine what protocol this port uses to communicate with the addon modules that can be plugged into it and what the correct connections are. Once I have determined the correct pins and protocol I should be able to write a script that will do the communication.I have done some research and probing with multimeter (I don't have an oscilloscope currently) and located a circuit diagram for the header on the mainboard (attached),What i have determined so far:Pin 1 0v - possibly rx?Pin 2 5v - possibly tx?Pin 3 5v - possibly tx?Pin 4 12vPin 5 GndI was wondering if anyone has any suggestions or pointers on what I could try to work this out?

author: Jwillis
author_rank: Super Contributor
timestamp: April 02, 2019, 05:34:33 am
content: USBhttp://www.hobbytronics.co.uk/usb-connector-pinout

author: abqa
author_rank: Newbie
timestamp: April 03, 2019, 10:17:21 pm
content: Quote from: Jwillis on April 02, 2019, 05:34:33 amThanks Jwillis, Can you help me understand what lead you to believe it is USB?From the reading, research I have done and pin voltages I believe it is unlikely to be USB.

author: Nusa
author_rank: Super Contributor
timestamp: April 03, 2019, 11:44:05 pm
content: I'd be more likely to guess I2C, especially if more than one device can be attached/chained off that. You're more likley to figure it out if you actually have one of those add-ons and some method of monitoring the obvious data lines (pins 2 and 3).You've committed the classic sin of failing to give us basic information that you have, such naming/linking the brand and model info on the air conditioner and the add-ons you're trying to emulate. That severely limits the ability of anyone to acquire the answer for you.

author: abqa
author_rank: Newbie
timestamp: April 04, 2019, 12:08:23 am
content: Thanks NusaIt is a Panasonic Split system from the CU/CSZ20TKR range (however this connector is common across many of the panasonic series)My understanding is only one addon can be connected at any time (not 100%sure about this)Modules available include:CZ-TACG1 Wifi kit:http://www.panasonic.hk/usm.ashx/e/7zt1rwYXAiWEX1X3Hkyy9Naxy7NSnBFA89YBELQe-2L0J2RMcxQSCsgXytHbtm7ZBFLpQZ8phzb451XTOV_fX3-xb7Vrxt1ft7KR-ODzZh6hNYcPgXEggCffw1CXZUluSh5e~UC~0Hc00GxCOL1ctdmAe6NNFvzxYL30cW-4zk8o/CZ-TACG1-WiFi-adapter-users-maunal.pdfIntesisBox PA-AC-BAC-1:https://www.intesisbox.com/intesis/product/media/intesisbox_pa-ac-bac-1_installation_manual_en.pdf?v=2.1Panasonic PAW-SERVER-PKEA -https://www.panasonicproclub.com/uploads/IE/catalogues/II_PAW-SERVER_PKEA_v44_EN_2013.pdfUnfortunately I don't have any of these available for testing with
Trouble on display LCD - Page 1
Forum section: electronics / beginners

author: koba30
author_rank: Contributor
timestamp: December 03, 2018, 03:30:37 am
content: Hi,I replaced a LCD display from a crane computer, but after a few day appear again the same problem that the first display faulty (black spot or lines)Which could be the cause?One picture show the two LCD Hosiden, a new and first LCD faulty, the other picture show the black spot on the new display.Thanks in advance for your comments.Enviado desde mi SM-G920I mediante Tapatalk

author: wraper
author_rank: Unknown
timestamp: December 03, 2018, 03:34:39 am
content: This happens due to cracks in bottom layer of glass (often happens with mobile phones) or loosing seal on the edge between glass layers. Could be because there is some mechanical stress applied. Might be delamination without loosing seal as well.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 03, 2018, 03:36:23 am
content: I'd say that's mechanical stress related too.
Trouble reproducing a schematic on Eagle - Page 1
Forum section: electronics / beginners

author: redgear
author_rank: Frequent Contributor
timestamp: August 20, 2019, 05:30:08 am
content: I am reproducing a schematic from TI's reference designs.SchematicWhat should be the voltage rating of the capacitors rounded in Red?Do those double arrows highlighted in Blue be they are connected to each other? How do I draw those symbols on Eagle?How can I get the pointed arrows on the end of the wire like the ones highlighted in black?Thanks

author: ggchab
author_rank: Frequent Contributor
timestamp: August 20, 2019, 04:38:25 pm
content: Choose the "Name" option in the vertical tools barGive the same name to the nets you want to join (Ex. C10)Click "Yes" when Eagle proposes to join the netsChoose the "Label" option in the vertical tools barYou can choose between several label formats in the horizontal barClick on the nets to attach the label
Trouble reproducing a schematic on KiCad - Page 1
Forum section: electronics / beginners

author: redgear
author_rank: Frequent Contributor
timestamp: August 16, 2019, 10:07:07 am
content: I am trying got reproduce a open source schematic on KiCad. The MCU also some pinouts missing. I am not able to find the same symbols for GND, 3V3 and the crystal oscillator. I guess the oscillator used here is a 4 pin oscillator but symbols are very different from what I see in KiCad. I have marked the symbols on the below image.Image

author: paulca
author_rank: Super Contributor
timestamp: August 16, 2019, 12:22:47 pm
content: The 3v3 symbol in KiCAD is the (more standard) upwards arrow. I'm not sure which category it's in.As to not having the 4 pin oscillator. You can ask if you need that, depending on whether you are trying to exacly replicate the schematic or the circuit as I'm sure the MCU can be made to work with a normally 2 pin one.Of course, almost all KiCAD schematics will require at least one custom component/symbol to be created.Another option is to search for add-on libraries. There are some quite large collections of these around. Sorry I don't have links, it's been a year or so since I did anything in KiCAD in anger.

author: redgear
author_rank: Frequent Contributor
timestamp: August 16, 2019, 04:31:50 pm
content: Quote from: paulca on August 16, 2019, 12:22:47 pmThanks! I am trying to replicate the same as I am just starting to learn and changing the components and tweaking it would be more difficult for me. Are they using a wire or bus for connections?

author: electricMN
author_rank: Regular Contributor
timestamp: August 16, 2019, 05:02:44 pm
content: I believe that crystal is one of the ones that have pins for grounding the case or they are indicating to ground the case with wire.

author: james_s
author_rank: Super Contributor
timestamp: August 16, 2019, 05:14:59 pm
content: Libraries have varying quality and some have hidden pins for power and ground, which is not something I like. Generally the only default symbols I use are basic stuff like capacitors and transistors, for everything else I create my own. It saves a lot of time in the long run.

author: Zero999
author_rank: Super Contributor
timestamp: August 16, 2019, 08:25:55 pm
content: X2 is not an oscillator, it's just a crystal. To make an oscillator an amplifier is required and in this case it's inside the MCU. The crystal is just the tuning element. It could be replaced with a ceramic resonator or even an LC circuit, but it wouldn't be as stable or as accurate as a crystal.

author: Bassman59
author_rank: Super Contributor
timestamp: August 18, 2019, 04:28:52 am
content: Quote from: redgear on August 16, 2019, 10:07:07 amThe Power library has all of the supply and ground symbols. What they actually look like doesn’t matter. But the name of the power symbol is also the net, so that needs to match.As for the oscillator, I know there is at least one Kicad library that has them. Again what it looks like probably doesn’t matter, as long as the pinout is correct.
Trouble reverse engineering PCB to schematic - capacitor to nowhere? - Page 1
Forum section: electronics / beginners

author: jpyeron
author_rank: Regular Contributor
timestamp: July 26, 2019, 04:20:45 pm
content: I am reverse engineering a commercial (constant current) LED ceiling panel, to make an open source replacement / improvement.The PCB has two capacitors on the PCB near the wires. They are 10.3uF.The board contains two circuits of LEDs 3k white, 5k white. The capacitors are only on one of the circuits. I have been unable to probe out where the other pad goes. Any thoughts on where to go next

author: KL27x
author_rank: Super Contributor
timestamp: July 28, 2019, 04:20:54 am
content: Doh. Better check IP address to see if this is Treez opening a fake account.

author: jpyeron
author_rank: Regular Contributor
timestamp: July 28, 2019, 05:44:02 am
content: I am not trez, I am easy to google if you care/need

author: Nusa
author_rank: Super Contributor
timestamp: July 28, 2019, 06:50:37 am
content: See what the voltage is across the capacitors when the panel is in operation. That'll at least tell you that it's not open-circuit. Which is an idea you shouldn't discard until proven otherwise.Beyond that, you haven't given us enough information. Your schematic of something you can't explain is probably less useful than some pictures of actual traces and components on the board. How is the light used with the two circuits? Both on always? Each one independently? One always on before the other?

author: jpyeron
author_rank: Regular Contributor
timestamp: July 28, 2019, 07:02:40 pm
content: The solder mask is a bit difficult to see through, my apologies.Here is a key photo:Here is a a video of the whole boards (1 with the capacitor still on, the other with them removed):https://youtu.be/gSdic5ZpIjUHere are photos of the the power supply shipped with the unit - it is being replaced.Sorry, I omitted the readings across the component. I get a transient spike of +/- 0.007v at power up on the circuit, then it stabilizes to 0v. I am powering it directly with a constant current bench supply.As to the function, at the end of the second board it uses a common +, power supply (should) allocate 0-100% on one set and 100-0% on the other - so yes they can both be on at the same time.The commercial specs are (if you want to google the product):Tunable White LED Panel Light - 2x2 - 4,300 Lumens - 40W Dimmable Light FixturePart Number: LPD-TWR22-40CRI 80 CRICurrent Draw 0.33A (330mA)Efficacy 108 lm/wIntensity 4300 LumenTotal Power Consumption 40 Watts

author: jpyeron
author_rank: Regular Contributor
timestamp: July 29, 2019, 03:31:16 am
content: The LED strips are driven by aNCE6005AS.Which get its input from 2 knock offr1210n531This pretty much ensures it is PWM based dimming.

author: jpyeron
author_rank: Regular Contributor
timestamp: July 31, 2019, 01:15:05 pm
content: Is there any other information I can provide?
Trouble shooting problem Technics SA-590 - Page 1
Forum section: electronics / beginners

author: muffenme
author_rank: Contributor
timestamp: February 11, 2016, 05:46:38 pm
content: Has anyone work on the Technics SA-590? Should this black wire, marked by red arrow, be connected to this post, marked with a blue arrow. This unit doesn't power up and I can't find a service manual for it.Thanks for any help.

author: mzacharias
author_rank: Frequent Contributor
timestamp: February 13, 2016, 01:39:58 pm
content: It's hard to be sure with this picture, but the black "wire" looks to me like it does not connect at all, perhaps only used to wrap and secure nearby wiring. This is a very common practice. If so, it would be substantially stiffer than other wires in that area. Additionally, one could look underneath where it connects to the board (the trace side of the board) and confirm that there is no connection there.

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 13, 2016, 01:47:52 pm
content: +1 It's just to wrap around the now loose hanging wires.

author: muffenme
author_rank: Contributor
timestamp: February 17, 2016, 12:51:36 am
content: thanks, that what I tough.

author: Audioguru
author_rank: Super Contributor
timestamp: February 17, 2016, 01:02:07 am
content: It is Japanese and is 30 years old. Kiss it goodbye, give it a nice funeral and bury or creamate it. I am still using an American HH Scott 341 FM stereo receiver (I got in 1964) that still works perfectly after I cleaned the silver tarnish off the switch contacts.
Trouble shooting reverse action on a mouseBot. - Page 1
Forum section: electronics / beginners

author: dennisyuki
author_rank: Contributor
timestamp: November 06, 2013, 12:51:31 pm
content: I am have breadboarded a mouseBot. Circuit attached. I get forward motion. But when the momentary switch is pushed, it is suppose to cause the robot to go backwards. I heard the relay buzz but the motor does not reverse.How can I troubleshoot this? Is the motor not getting enough power? If so how do I check this? Use a meter in parallel with the motor to check Volts? I got the motor out of a toy so I do not know its specs.

author: dennisyuki
author_rank: Contributor
timestamp: November 08, 2013, 01:40:00 pm
content: I did some looking at the wiring last night on the relay in the schematic. I am not sure exactly ho the relay is set up internally, but I think the wires that cross and connect the pins together (pin 11 to 8 and 9 to 6) might be crossing to the wrong ones.Is this why I am not getting the reverse function?

author: dr_p
author_rank: Frequent Contributor
timestamp: November 08, 2013, 02:20:47 pm
content: I think the motors should be connected to the common (C) switches on the relay. Yours might differ in pinout from the one in the picture/schematic.

author: dennisyuki
author_rank: Contributor
timestamp: November 08, 2013, 07:44:24 pm
content: I pulled the data sheets on the relay they used and the one I bought. They are total different set ups. So when I go home I will try to correct the schematic to fit my relay.I will post my results.

author: MacAttak
author_rank: Unknown
timestamp: November 25, 2013, 03:39:29 am
content: Heh I recognize the diagram. It's the Mousey the JunkBot from Maker Shed. I made one last xmas (my wife bought me a few small kits for fun). Annoying as hell to assemble since they assume you are doing it free-form, and I really hate mess. So I threw together a PCB layout small enough to fit and sent it off to OSH Park. Yeah, a custom PCB is a tad overkill. Here is the project if you want to re-use it:http://oshpark.com/shared_projects/eYPlTGi4Obviously it will only be useful if you have the proper relay and other parts.Not exactly an awesome design, but I suppose for a simple project it's fine.

author: dennisyuki
author_rank: Contributor
timestamp: December 06, 2013, 09:28:19 pm
content: Thanks for the reply. How did you like OSHpark? How many boards did you get made? Thanks for the design. I will take a look at it this weekend.

author: MacAttak
author_rank: Unknown
timestamp: December 06, 2013, 11:24:54 pm
content: OSHPark has good service and is quick. I've used them several times and have no complaints.All boards from them are only available in threes (even if you only need one).
Trouble shooting  - Page 1
Forum section: electronics / beginners

author: joshuajcmacdonald
author_rank: Newbie
timestamp: December 01, 2022, 03:12:31 pm
content: So I was recently given some new gear (yay!) But in just a few days the power supply quit. I took the unit appart and found the black dust all though. My fist thought was a capacitor. So I checked each one desoldering and checking with a meter before putting them back an and they were all 110%. I have stange power values going into the dc to dc transformer. I have seen motors make the dust but not a transformer. Also getting some strange readings from the transistor just before the power goes to the stepndown transformer.Can I check the transistor with a multimeter in circut? Also I have voltages on one side of the transformer intermittently but then nothing on the other side. I am considering it dead. Anyone albe to help me?

author: Manul
author_rank: Super Contributor
timestamp: December 01, 2022, 03:50:12 pm
content: Quote from: joshuajcmacdonald on December 01, 2022, 03:12:31 pmSorry, but your post is about nothing. "Some new gear", "black dust", "strange power values", "some strange readings", "voltages on one side".Please post device model, some description, picture of PCB, describe the measurements you did and the values you've got. Then someone might be able to help you.Welcome to the forum.

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 02, 2022, 01:27:35 pm
content: The new gear is used? If they are new they should have some warranty. If new gear without warranty then they are not something you want.
Trouble spreading solder paste for MCU - Page 1
Forum section: electronics / beginners

author: Peacefrog
author_rank: Contributor
timestamp: May 04, 2020, 05:02:12 am
content: I've designed a PCB for a LQFP MCU which I'm attempting to assemble in my reflow oven. However, while the supporting 0603 parts are coming out fine, I *cannot* get the paste for the MCU right - it's ending up smeared between the pads every time.I'm using the stencil from the manufacturer (JLC), am really careful to have a steady hand when removing it, and the board is flat on my desk surrounded by other PCBs to keep everything level. Two other data points are that I'm using the credit card-style spreader that came with an earlier order from OSH, and the solder paste is Chip Quik's TS391AX10.Any suggestions? Thanks!

author: Dave
author_rank: Super Contributor
timestamp: May 04, 2020, 08:05:42 am
content: Lift the stencil by keeping one edge pressed against the table and flex the stencil up until all of the stencil openings are clear of the PCB.The surface finish of the PCB might be problematic as well. Did you order HASL? That might not allow the stencil to sit completely flat on the board, allowing the paste to smear under the pads.The third thing that comes to mind is the paste viscosity. If the paste is too runny, you might have trouble getting consistent results. Refrigerating the paste will make it thicker.

author: Simon
author_rank: Unknown
timestamp: June 17, 2020, 10:09:07 am
content: You need a stencil printer. I had the same problem. Through a miracle of grit, determination and ingenuity I got a QFN to solder the same way you are doing it but vowed never again. I have now ordered an SD-240 as I just need things to work. You need the stencil held down so that paste cannot squeeze under the stencil overdosing it. When you have consecutive pins close together the dosing is very important as all that excess on all those pins has to go somewhere. On fine pitch accurate positioning is also important. On large parts you have more error allowance but as the pitch goes down so must any error, what is a bit to one side on a large pitch can be totally off on a smaller pitch.
Trouble turning on high side MOSFET in H-bridge circuit - Page 1
Forum section: electronics / beginners

author: Capacitor_1886
author_rank: Newbie
timestamp: October 04, 2022, 05:44:24 am
content: Hi, i am designing an h-bridge circuit to control a brushed dc motor and after trying to test this circuit out on the pcb i have failed to get the circuit to work. Only my low side MOSFETS turn on and the voltage on my high side fets remains in the mV range. I am unsure on what is happening, i have probed with a scope and traced my signals all the way to the input of my drivers and after the drivers the high side signal comes out very messy and in the mV range. I just want to understand if i did something wrong on my design or if there is something i am not understanding fundamentally. On the simulation everything comes out nicely, my high sides turn on and everything is fine, but on the pcb the high switches remain off.For more context:I am using an all N-MOS design, so 4 n-channel MOSFETsThe mosfets: ixfb210n30p3The gate driver: dgd2190mAny comments or suggestions would be greatly appreciated

author: fourtytwo42
author_rank: Super Contributor
timestamp: October 04, 2022, 09:30:33 am
content: Almost certainly your problem is related to frequency of operation or duty cycle being such that the boost capacitors are unable to charge, this is compounded by your static discharge of them through the 10K gate-source resistors on the high side.If you want this circuit to work down to DC you will have to provide a separate permanent boost supply.
Trouble understanding Schmitt Triggers - Page 1
Forum section: electronics / beginners

author: sci4me
author_rank: Regular Contributor
timestamp: June 16, 2015, 11:53:39 pm
content: Hey guys! So I have noticed that a lot of things seem to use Schmitt Triggers. I think I understand what a Schmitt Trigger actually does, but so far I don't get why they're used in certain places. Take the 74LS245 for example. Looking at the diagram, there are Schmitt Triggers. Why?

author: w2aew
author_rank: Super Contributor
timestamp: June 17, 2015, 01:54:11 am
content: The first part of my video on Schmitt trigger oscillators describes what a Schmitt trigger is and why it's used.

author: sci4me
author_rank: Regular Contributor
timestamp: June 17, 2015, 02:08:37 am
content: Okay so that makes sense to me... and relating it to general logic gates, is it used just for dealing with noise on logic signals?

author: w2aew
author_rank: Super Contributor
timestamp: June 17, 2015, 02:17:19 am
content: Quote from: sci4me on June 17, 2015, 02:08:37 amPrimarily, yes. It helps prevent 'chattering' for noisy or slowly changing (slow rise/fall time) logic input signals.

author: jwm_
author_rank: Frequent Contributor
timestamp: June 17, 2015, 02:31:13 am
content: You can also use them in a pinch to perform a lot of logic operations with only diodes and resistors. They are quite handy.http://www.musicfromouterspace.com/analogsynth_new/ELECTRONICS/mickeymouselogic.htmlThere are a lot of circuits you can make with just a hex schmit as your only chip and some discretes, the classic time domain reflectometer is onehttp://notanumber.net/archives/110/experimenting-with-a-homebrew-time-domain-reflectometer

author: sci4me
author_rank: Regular Contributor
timestamp: June 17, 2015, 11:17:16 am
content: Alrighty then I think I got it. Thanks guys!

author: vk6zgo
author_rank: Super Contributor
timestamp: June 20, 2015, 03:46:26 am
content: Schmitt trigger circuits also have many applications in what would be generally regarded as analog circuitry.They can be used to produce a square wave when fed from a sinewave.This was used for many years as a way to synch things to AC mains frequencies.Another use is to trigger some function when a signal reaches either the upper or lower limits of the device.A classic example is in an AM Modulation Monitor where a Schmitt trigger may be used to flash an over modulation light.
Trouble understanding specs of 3fase transformers.  - Page 1
Forum section: electronics / beginners

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: November 26, 2015, 08:40:00 am
content: So I have an assignment I'm trying to do. It regards 3 phase transformers (not going to copy the assignment because I want to solve it myself). I do have a question about the specsheets tho.I'm given that I have a transformer with following specs:Wired Yy0, 36kV/400VSnom (in KVA) = 4000Po (kW) is 5.5Pk (kW) is 33And uk is 6.0%Now my question is regarding the voltages. The rated 36kV/400V are those line or phase voltages? Or is it impossible to know? (the assignment mentions it will not provide you with all the necessary information and I will have to make assumptions). It would make sense if it were linevoltages as the line voltages in Belgian domestic circuits are 400V, but I would rather double check since is the first step in a long assignment and I'd rather not go wrong now.EDIT: corrected the use of "fase" to "phase"

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 26, 2015, 09:15:44 am
content: Somewhere in the textbook, it should say the customary measurement is line-to-line.Also, it's "phase".Tim

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: November 26, 2015, 09:26:23 am
content: Thanks! I went through the book 2ce and didn't really find any mention of it... Probably some footnote somewhere I read over.And I feel stupid for writing fase instead of phase,I should've known...

author: tautech
author_rank: Super Contributor
timestamp: November 26, 2015, 09:34:08 am
content: Quote from: T3sl4co1l on November 26, 2015, 09:15:44 am+1Here 3 phase is 415VAC between phases and 230VAC to mains neutral/GND

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: November 26, 2015, 11:20:59 am
content: Quote from: T3sl4co1l on November 26, 2015, 09:15:44 amI think I somewhat found it: In the textbook, it is mentioned that in all equivalent circuits for power/voltage/current/whatnot calculations, it will be assumed that the transformers are actually Yy0, no matter what their actual internal wiring scheme is.Now I'm just stuck on some other stuff but I'm gonna spend some more time looking at it and reading through the literature - our lecturer isn't consistent in his use of symbols, one subsection Ikn=Nominal short circuit current, next subsection he uses Ik for the same thing... But never does he explicitly mention what he will be using from this point on, so you just have to connect the symbols yourself and hope you did it right... Sure it might be obvious once I'm familiar with the subject and concepts, but for now it's really quite confusing... /endrant
Trouble using buck-boost driver for constant-current LED source! - Page 1
Forum section: electronics / beginners

author: SittingBear
author_rank: Contributor
timestamp: July 17, 2014, 01:49:55 pm
content: Hello EEVBlog community,I'm having a lot of difficulty in properly getting a constant-current buck topology circuit going for 2 white LEDs with a forward voltage of ~3.5V.The buck circuit I am using is pretty simple and is found in page 1 of the datasheet for the buck-boost driver I am using found here:http://www.onsemi.com/pub_link/Collateral/NCP3066-D.PDFThe datasheet is not very descriptive in my opinion, and I have looked at other datasheets of near identical drivers. I was able to properly figure out and work a constant voltage setup, but that isn't what I want. Before you ask and or find it, yes there is a design tool for both buck and boost topologies. However, after extensively playing with the values from this design tool I have come to the conclusion it is not at all good at predicting values for an accurate or clean outcome. I believe the formulas make a lot of incorrect assumptions in what actually happens.Any help on this would be great! I also have a copy and have started to read, along with skimming through more relevant chapters, the "Fundamentals of Power Electronics - Second Edition" book which goes into extreme detail about buck, boost, and other regulating circuits.Thanks!-Bear
Trouble with identifying a resistor - Page 1
Forum section: electronics / beginners

author: FloridaTony
author_rank: Newbie
timestamp: January 31, 2020, 03:04:43 am
content: I am having quite the time trying to identify a blown resistor for a power board. The resistor is clearly an "Orange-Orange-Silver-Gold-Green" resistor, but it seems like nowhere I try to look and identify it, even on DigiKey. It won't recognize the 3rd band as being silver. Any clues?I have even attached a picture of the resistor in question.

author: WattsThat
author_rank: Frequent Contributor
timestamp: January 31, 2020, 03:14:53 am
content: 0.33 ohms 5% 20ppm tempcoNot sure about the power, it’s hard to estimate size. Is it being used as a current shunt? That’s what the value and tempco would imply.

author: FloridaTony
author_rank: Newbie
timestamp: January 31, 2020, 03:28:18 am
content: I would believe so. It is a fairly chunky resistor that is before a fair sized mosfet with a heat sink on it.

author: FloridaTony
author_rank: Newbie
timestamp: January 31, 2020, 03:44:58 am
content: After plugging that info into DigiKey, I may have found the replacement. It also seems like a 1 Watt resistor, especially from the measurements I took with the caliper.
Trouble With LM393 Comparator Circuit - Page 1
Forum section: electronics / beginners

author: drillionaire
author_rank: Newbie
timestamp: January 07, 2015, 11:45:57 pm
content: I'm having an issue with a dual comparator circuit that I designed. The input is a signal varies from 0v to a steady 5v with 10v pulses that last 10ms.I designed this circuit to turn the single input into two outputs, one that goes high to 5v when the input signal has a 10ms 10v pulse, and one that goes high to 5v whenever the input signal is at 5v.The trouble I'm having is that when the input signal goes high at all, both outputs of the LM393 comparators stay high at V+.I've tried changing the value of the 10M ohm feedback resistors (R11 and R12), and I've bypassed and removed from the board the op amp buffer between the input signal and the comparator as it was oscillating oddly when I had it in the circuit.The only thing that seems to work is touching one finger to the input pin and another finger to ground. When I do this, the output of the comparators is accurate compared to the input, and it doesn't hang at V+ regardless of the input voltage.I tried adding various sizes of capacitors between the input and ground, and I tried adding a 10M resistor between the input and ground. None of these solutions seem to work.I'm not sure what else to try to get the comparator to stop getting stuck at V+ when there's any input voltage applied to it.Any help is appreciated, thanks!Here's the comparator circuit:This is the circuit that is generating the signal that is being input to the comparator circuit:

author: eejake52
author_rank: Contributor
timestamp: January 08, 2015, 11:18:42 pm
content: First one picky point: Your resistors R11 and R12 are providing positive feedback, which provides hysteresis on the input. I would call them hysteresis resistors, since 'feedback' resistors usually connect to the -ve input.Second, the reason that the hysteresis isn't working is because of the diode D1 in the driving circuit. There is no path to ground, so the junction of R9/R11 can never get low enough to overcome the hysteresis. When you touch pin 3 with one finger and ground with another, you are providing a ground path through your body.I suggest a 10k pull down resistor on the input will likely work. You may want to simulate the setup on LTSPICE (or any simulator program) and see what value works best; or build it on a breadboard and determine it empirically.Jake

author: drillionaire
author_rank: Newbie
timestamp: January 08, 2015, 11:58:24 pm
content: Thanks for the clarification on the terminology.I used a 12k resistor (had it on hand) and it did the trick!I had tried a 10M resistor before, but I guess it was taking too long to pull the R9/R11 junction to ground.I've been prototyping the circuit on a CNC isolation milled PCB, which worked out nicely.Thanks for the help!
Trouble with making a ws1208b lamp - Page 1
Forum section: electronics / beginners

author: 1ABengineer
author_rank: Newbie
timestamp: February 24, 2025, 03:34:53 pm
content: I am trying to make a RGB led lamp for my sailboat.It will be powered by twelve volts and has a rs485 transceiver to communicate to a m5dial.To start out I made a prototype board, and used an off the shelf ws2812b matrix board for testingmy final design has 47 ws2812 LEDs, which needs way more power than the L7805 can deliver. so I decided to split the LEDs up in two power rails, one powering 24 LEDs and the other powering 27 LEDs.When I tested it with 24 LEDs my lab power supply told me it was taking 420mA at 12 volt.Which I found strange because a ws2812b led at full power uses 60mA and 24 * 0.06 = 1.44A.Besides that, the L8705 became hotter than I like.So for the final board i decided to use another linear voltage regulator for each power rail n.l. the LM1084 which can handle 3Aafter building the final board it worked , the LEDs (at 50% as programmed) and the rs485 worked. But the LM1084's became really hot and my board stopt working within minutes. I led it cool down, and the voltage regulators still gave 5 volts and I could connect to the processor, but the LEDs did not seem to work anymore.The LM1084's came from AliExpress, i don't have great confidence that they are not fake'squestions:1.in my head if a circuit draws 420mA at 12 volts the L7805 can not deliver more than 420mA. in practice this assumption does not hold water, can it deliver more?2.Is a linear voltage regulator that can handle 3A cooler than a voltage regulator that can handel 1.5A at a load of 1.44A?3.Any tips on how to trouble shoot this? Before I buy the same regulators from mouser(20 euro shipping makes this expansive )4.was it a bad idea to split the LEDs up in two power rails, it is the first time for me to have more than 1 power rail.Any help Will be greatly appreciatedgreetings Bert

author: ledtester
author_rank: Super Contributor
timestamp: February 24, 2025, 03:47:06 pm
content: Use a switch mode power supply.What power do you have on your boat? If you have AC power (like 110V / 220V) you can just use a 5V power adapter (also called a "wall-wart").If you only have DC power then you can use a buck converter to convert 12/24V (or other voltages) to 5V.Both solutions are much more efficient than linear regulators and will produce a lot less heat.

author: 1ABengineer
author_rank: Newbie
timestamp: February 24, 2025, 05:10:37 pm
content: thank you ledtester.I will research buck and switchmode power supply.I have a 12-volt DC systeem, 220, maybe in the future
Trouble with replacing HD44780 16x2 LCD with VFD - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: February 06, 2018, 11:44:09 am
content: Hi all,I have replaced many old non backlit or just worn out HD44780 on some older gear (Intel 8031 powered) with the $2-3 ones you can get from China. The cheap ones always work perfectly for me when replacing old 44780... this time I decided to get a little fancier and order a Noritake CU16025ECPB-W1J VFD as it says it's 44780 compatible.The only problem is.... it doesn't light up when I plug it in! I'm sure I have it wired right because either the original LCD or one of the China LCDs which i've soldered to a 2x7 IDC ribbon lead works just fine.Is there any chance the power supply might be too slow to get the display to reset itself and maybe that is the issue? I was going thru the datasheets to try and find what could be the cause. I've triple checked my wiring and checked every lead for continuity, etc, so i don't think my soldering is the problem here.Datasheethttps://media.digikey.com/pdf/Data Sheets/Noritake PDFs/CU16025ECPB-W1J.pdfMany thanks in advance to anyone who might have an idea what is going on here and why this VFD isn't cooperating as easily as the $2 44780-compatibles i've been buying.(Service manual for the device i'm trying to install it into if anyone cares:www.warningwillrobinson.com.au/manuals/Alesis%20MMT8_Service_Manual.pdf)(Datasheet for the cheapo 44780 compatibleshttps://www.buydisplay.com/download/ic/SPLC780.pdf)

author: danadak
author_rank: Super Contributor
timestamp: February 06, 2018, 11:58:04 am
content: Many VFD modules have a self test mode that can be forced with a pin onpower up, does this one have a jumper to do this ? So you can verify ifVFD is working.Regards, Dana.

author: Mp3
author_rank: Frequent Contributor
timestamp: February 06, 2018, 12:14:44 pm
content: Quote from: danadak on February 06, 2018, 11:58:04 amGreat idea, thanks a bunch Dana!I found on this manual how to set the self test mode, shorted those jumpers and sure enough saw dancing snowflakes on screenhttp://www.oflittleinterest.com/VFD/CU16025ecpb-w6j_e00.pdfNow just to figure out how to get it to show the letters I want. I will sleep on it and hopefully have a revelation later about it.(I did notice it expects a command to let it know if it should be operating in 4 bit or 8 bit mode. I'm not sure if my device tells the screen that info.)
Troubles driving a power FET. - Page 1
Forum section: electronics / beginners

author: truhlik_fredy
author_rank: Regular Contributor
timestamp: February 25, 2012, 03:02:57 pm
content: I have this coolmos kind of power FET, IPP60R385CP. And I wanted to switch with it around 200V, but I can't open it. So I lowered voltages and input is now around 20V and base around 15V, but still every time I have just base voltage on output not the input voltage. It's like voltage follower. I can't fully saturate base or what could be wrong that I can't open it fully?I read datasheet to it, but still can't find what could be wrong. It's my first interaction with power fets so perhaps I'm missing something, or that fet make is somehow special?I don't want to use different fet because later it should be a power device and I got requirement to base it on that FET. So I started to experiment with FET if I can drive it properly and it looks like I can't. Any Ideas what could be wrong?

author: jahonen
author_rank: Super Contributor
timestamp: February 25, 2012, 03:08:16 pm
content: You'll need a high-side driver (IR2110 or similar) to get the behavior you expect.Regards,Janne

author: truhlik_fredy
author_rank: Regular Contributor
timestamp: February 25, 2012, 03:26:56 pm
content: Quote from: jahonen on February 25, 2012, 03:08:16 pmIR2110 has VOUT 10-20V that I'm feeding manually to base of the fet.

author: jahonen
author_rank: Super Contributor
timestamp: February 25, 2012, 03:37:28 pm
content: High-side driver outputs that relative to the FET source, so gate voltage is 10-20 volts above the supply voltage when the FET is fully open.Regards,Janne

author: truhlik_fredy
author_rank: Regular Contributor
timestamp: February 25, 2012, 03:46:00 pm
content: Quote from: jahonen on February 25, 2012, 03:37:28 pmSo when I have 20V on input and want it on output I have to feed around 35V on base to have fully opened, right?

author: jahonen
author_rank: Super Contributor
timestamp: February 25, 2012, 03:59:21 pm
content: Quote from: truhlik_fredy on February 25, 2012, 03:46:00 pmYes.Regards,Janne

author: truhlik_fredy
author_rank: Regular Contributor
timestamp: February 25, 2012, 04:08:43 pm
content: Ok thank you very much.
Troubles programming Rigol DS1102CD with Labview - Page 1
Forum section: electronics / beginners

author: nekromendis
author_rank: Newbie
timestamp: June 21, 2010, 10:02:41 pm
content: Hi,I am trying to programm a Rigol Scope DS1102CD with firmware version 03.03.01 using Labview 8.6. I install the last version of VISA however the USB resource is not detectable by MAX it is only detectable when I generate the driver with Driver Wizard but the programm does not work setting USB RAW I supose should be USB INSTR. Someone could help me?I download the Rigol example using Labview but it doesnt work USB can not be detectableCould be the firmware version?
Troubles with c code for pic  - Page 1
Forum section: electronics / beginners

author: little_carlos
author_rank: Regular Contributor
timestamp: August 31, 2015, 12:24:10 am
content: sup guys, im trying to make a selector between 3 choices using one button for each choice, the third one is a blinking led but because of the "while" that i have to use in that specific part i cant go back to the other choicescan i use "goto" or other code to be able to return to main part of the code or what do i have to do?this is the code#define ENTRADA_BOTON PORTD.F1 //asi se crean variables#define SALIDA_LED PORTB.F0void main() {//////////////////////////////////////////////////////////////////////////////////////ANSEL = 0; //desactiva e/s analogicasANSELH = 0; //desactiva e/s analogicasTRISD = 1; // 1= inputPORTD = 0;TRISB = 0;PORTB = 0;//////////////////////////////////////////////////////////////////////////////////////////marca1:while(1){ // se usa para establecer este proceso infinitoif(PORTD.F1 == 1) { // el ".F1 declara el bit del puerto, en este caso, RD1PORTB.F0 = 1;}else{PORTB.F0 = 0;}if(PORTD.F2 == 1) {PORTB.F1 = 1;}else{PORTB.F1 = 0;}if(PORTD.F3 == 1){while(2){delay_ms(1000);PORTB.F2 = 1;delay_ms(1000);PORTB.F2 = 0;}}else{PORTB.F2 = 0;}}}

author: MarkF
author_rank: Super Contributor
timestamp: August 31, 2015, 01:21:13 am
content: Try this:Code:void main(){int frame=0;int state=0;while (1) {if (PORTD.F1 == 1) state=1;if (PORTD.F2 == 1) state=2;if (PORTD.F3 == 1) state=3;switch (state) {case 1:PORTB.F0=1;PORTB.F1=0;PORTB.F2=0;state=0;break;case 2:PORTB.F0=0;PORTB.F1=1;PORTB.F2=0;state=0;break;case 3:PORTB.F0=0;PORTB.F1=0;frame=0;state=4;case 4:if (frame < 5000)PORTB.F2=1;elsePORTB.F2=0;if (frame++ >= 10000) frame = 0;break;}}}
Troubleshoot car amplifier "Renegade ren1100s mk2"  - Page 1
Forum section: electronics / beginners

author: Bastel1991
author_rank: Newbie
timestamp: December 24, 2016, 10:29:49 pm
content: Hey @all,Im trying to troubleshoot the amplifier that's named in the title, the main fault is that it's literally destroying everything you hook up to it on the front channel, I checked with my multimeter the output and I get almost 21 volts without any signal that it could be amplified.My first thought was that one of the 4 power transistors is gone bad, but I'm not really sure how to test them I tried various methods with the multimeter on diode test but if I done it right and my readings are correct 3 out of 4 power transistors are gone bad and somehow I can't believe this.Can anyone give me a hint in the right direction?Thanks for you time

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: December 25, 2016, 12:27:56 am
content: Hi,why do you think this can't be? It is a fairly common fault that the power transistors blow up, so no problem with that.But how did you test those?
troubleshoot practice - Page 1
Forum section: electronics / beginners

author: ilyas_te
author_rank: Newbie
timestamp: November 18, 2014, 08:43:39 am
content: hi guys,I am very happy to be among of you.Please be my GURU.Can anybody tell me where i can find some basic circuits for troubleshoot practice? I need them to improve my knowledge in electronics workshops. Thank you very much.

author: Paul Price
author_rank: Super Contributor
timestamp: November 18, 2014, 04:52:18 pm
content: In any electronic equipment garbage disposal spot, ask friends and neighbors, there is a reason it is ready to be thrown into the trashcan.Notice that there is a Repair section to this forum, plenty there to learn from.

author: Derick Freese
author_rank: Contributor
timestamp: November 20, 2014, 06:30:02 pm
content: I learned all of my repair skills from garbage bin finds.

author: ilyas_te
author_rank: Newbie
timestamp: November 25, 2014, 05:33:57 am
content: I am sorry for my late responsethank you for Mr. Price and Mr. FreeseHowever, do you think that they are too complicate for me as beginner?Can you guys tell me about your experiences when you were trying to troubleshoot a circuit for the first time?For me, it is very difficult to decide the first area that i need to check when handling the trouble circuit.Thank you for helping me.

author: IanB
author_rank: Super Contributor
timestamp: November 25, 2014, 06:19:21 am
content: It will be nearly impossible to troubleshoot a circuit unless you know how it works. You will need prior knowledge of similar circuits, or a schematic, or a repair and troubleshooting guide (or all of these).In general, you start with the power supply and make sure the right voltages are present in the right places. After that, you follow the signals from input to output and see where things start to look wrong.
Troubleshooting a light up Christmas village piece - Page 1
Forum section: electronics / beginners

author: admiral_akmir
author_rank: Newbie
timestamp: January 01, 2017, 01:02:54 am
content: So my mom got this little snow covered bridge with LED lights on it for Christmas. She complained that it didn't work, so I took a look at it. It's got two wires going into a small control box with a slide switch. Power comes from two AA batteries. When I opened it up, it became apparent right away that this was regifted. The inside was covered in dried battery acid, and the solder joints were gross and corroded.I took out the batteries and pried out the metal battery connections and cleaned them with baking soda and warm water. I desoldered the wires on the switch and battery terminals, tried to get all of the burned flux and gunk off with rubbing alcohol, then started to troubleshoot why it wouldn't light up.I touched the two wires coming out of the bridge, against both ends of one AA battery and it lit up, so I know the issue is not internal. I got the cleaned battery terminals back in the plastic housing of the control box, put the batteries in and tested this connection... Nothing. Here is a picture of the housing;I should be able to touch the wires from the bridge to terminals A and B and have the bridge light up, but it doesn't do anything. If I stick a copper wire between terminal A and the battery, and touch the bridge wire to that instead, it works. So my question is, what could be happening with terminal A? Is it possible that I overheated the terminal when desoldering and somehow compromised the conductivity of the metal? Maybe it's not cleaned off well enough?

author: admiral_akmir
author_rank: Newbie
timestamp: January 01, 2017, 02:37:15 am
content: Guys, I figured it out. For some reason that battery terminal was backwards. Usually the bump in the metal faces in towards the positive side of the battery, in this case it was built to face the other way for some reason. I used some pliers to bend the terminal the other way, then reinstalled it and it worked. Looks like the connection was just incomplete, even though it looked okay. Probably the bottom, insulated part of the battery was the only thing touching.

author: Seekonk
author_rank: Super Contributor
timestamp: January 01, 2017, 05:25:53 am
content: I have trouble with COSTCO AA batteries. Their positive end is wider and shorter and it hangs up on plastic mounting.