hybridfree/eevblog-posts huggingface dataset:
Copper Pour questions with Isolated DC-to-DC encapsulated SMPS design - Page 1
Forum section: electronics / projects

author: K3mHtH
author_rank: Regular Contributor
timestamp: May 23, 2021, 07:25:45 pm
content: Hey everyone,I'm designing a PCB for a little CUI encapsulated isolated DC-to-DC power supply (+/-15V) and looking for some tips regarding the copper pour. My "ground" connection is currently on the load side.. I'm worried that having this as the copper pour across the board, underneath inductors and the SMPS might induce switching noise into my ground?Clearly I'm a bit over my head here, and just looking for some general advice.Here is the DC-to-DC I'm using:https://www.cui.com/product/resource/pdqe15-d.pdfMy circuit is copied from Page 6, Figure 4.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 23, 2021, 09:57:31 pm
content: What are you isolating? Are there conducted or radiated paths from both sides (ground/earth connections, connectors/cables, etc.)?Note that those things are tested basically alone, no common mode data. Expect to need an external CMC if you need it quiet.And how much noise can you tolerate? Functional or regulatory..?Tim

author: K3mHtH
author_rank: Regular Contributor
timestamp: May 23, 2021, 11:16:12 pm
content: The input is isolated from the output, to avoid possible ground loops - this is in an audio device.The PSU is on a separate PCB with a 3 pin connection leaving it (for +15, GND, and -15). There is also a 2 pin connector for a power LED, powered off the -15V.I currently have a common mode choke on the input, since I noticed it made things a lot less noisy during my breadboard testing with an oscilloscope.Basically I'm just wondering what best practices are for ground planes, if there should or shouldn't be any - especially under the CMC, inductors and DC-to-DC itself. And what that ground plane should be connected to (unconnected, input voltage ground (before or after CMC), output voltage ground, etc.). I hope that helps.

author: K3mHtH
author_rank: Regular Contributor
timestamp: May 24, 2021, 12:12:29 am
content: Here's a schematic if that helps.There is a +15/-15V supply that goes to internal audio components. The 9V output goes to external stuff, where some stuff can be connected as -9V with the + rail being grounded.
Copper to Board-Edge clearance for DFM - Page 1
Forum section: electronics / projects

author: eecook
author_rank: Regular Contributor
timestamp: November 04, 2014, 03:20:55 pm
content: Hi all,I am working on a design where DFM is a concern. In particular I need to know what IPC has to say regarding copper to board edge clearance. Going through IPC-2222 I get to section "10.1.1 Edge clearance" but it only talks about copper to copper clearance as a function of voltage. I also went through IPC-7351 but is only for components and doesn't mention copper in particular.I have worked with several manufacturers in the past and I know that in terms of manufacturing capabilities virtually anyone can deal with a 1mm clearance. But that's not good enough for my project manager who wants an "authoritative opinion" on the matter. I have wasted the whole morning googling and... nothing.Does anybody know about any document out there that covers this subject, or at least something to shut him up?Cheers!

author: free_electron
author_rank: Super Contributor
timestamp: November 04, 2014, 03:48:19 pm
content: 0.5mm pullback is typical to avoid routing shorts. if you want to seal the internal structure : 2 mm will do it. this allows the prepregs to fuse properly without risk of peeling later.

author: IconicPCB
author_rank: Super Contributor
timestamp: November 04, 2014, 08:37:27 pm
content: Talk to Your board shop... after all they are the ones who will have to make it.
Copper wires in Optical HDMI cable - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: June 25, 2020, 03:29:53 pm
content: Hi,in HDMI optical cables there are some copper wires (see attached image). What signals are they carrying? I could not find any pinouts online.Thank you

author: mariush
author_rank: Super Contributor
timestamp: June 25, 2020, 03:44:29 pm
content: If I were to guess, the fibers are used for the actual high bandwidth stuff, and the wires are used for the low bandwidth stuff (auxiliary, network etc) and to transfer a bit of power to the other end to power the converter that converts the data on fiber back to regular wires ... just in case the remote device does not provide enough power or no power at all.See pinout on the side of this page :https://en.wikipedia.org/wiki/HDMIPin 1 - 12 : 3 TMDS pairs and their shielding.Pin 13 CECPin 14Reserved (HDMI 1.0–1.3a)Utility/HEAC+ (HDMI 1.4+, optional, HDMI Ethernet Channel and Audio Return Channel)Pin 15 SCL (I²C serial clock for DDC)Pin 16 SDA (I²C serial data for DDC)Pin 17 Ground (for DDC, CEC, ARC, and HEC)Pin 18 +5 V (min. 0.055 A)Pin 19Hot Plug Detect (all versions)HEAC− (HDMI 1.4+, optional, HDMI Ethernet Channel and Audio Return Channel)

author: RoGeorge
author_rank: Super Contributor
timestamp: June 25, 2020, 05:41:05 pm
content: "Pure Glass" Optical Fiber, 8 "pure Copper" Cores, "Anti-EMI" Aluminium Foil Layer, "ECO-Friendly" & "Safety" TPU
Copy an existing, populated, PCB board? - Page 1
Forum section: electronics / projects

author: Chris Wilson
author_rank: Super Contributor
timestamp: September 19, 2012, 01:20:13 pm
content: I have a small and simple plug in PCB board from a power supply on its way to me, inside a partially working PSU. It is the same board that is missing altogether from a sister none working supply I have, that gives a hefty 60 volts, 50 amps variable output that I want to fix. I could de solder and remove all the components off the board I am getting, and thought I could maybe take some sort of "brass rubbing" tracing of the tracks, but is there a better way? I would like to try and etch a board myself but have never tried anything more than very basic stuff of my own design, with the tracks blanked of with cut vinyl tape, or marker pen. Thanks.

author: SeanB
author_rank: Super Contributor
timestamp: September 19, 2012, 04:20:31 pm
content: Good digital camera and a pair of rulers on the board edges. Photograph from above, with an even light to illuminate the board, and use a graphics program to convert to a greyscale and posterise the image to a black and white image, with the traces in black and the board in white. Scale to the right size and print as an image and use a photosensitive board, or send to a PCB house to do. Check the tracks match on a test printout, and when correct you can get the board made and drill it yourself.

author: grumpydoc
author_rank: Super Contributor
timestamp: September 19, 2012, 04:25:18 pm
content: Single or double sided.I've been thinking of the same for a couple of PCBs - and pretty much planning on using the process outlined by SeanB. It possibly helps that I have a copy of photoshop to tweak the image.

author: Chris Wilson
author_rank: Super Contributor
timestamp: September 19, 2012, 04:44:34 pm
content: Single sided and quite uncomplicated. Will give it a shot when it arrives, haven't played with photo sensitive boards yet, wouldn't mind having a go with that too though! Thanks again Sean, great info, and appreciated.

author: krivx
author_rank: Frequent Contributor
timestamp: September 19, 2012, 05:45:33 pm
content: I have used a flatbed scanner to scan PCBs in the past. It works much better than a digital camera, the level of light across the board is very even and there is very little distortion. If you put a reference object (say, a ruler) on the scanner at the same time it makes rescaling the image for correct dimensions pretty straightforward.

author: AndyC_772
author_rank: Super Contributor
timestamp: September 19, 2012, 05:54:56 pm
content: Quote from: grumpydoc on September 19, 2012, 04:25:18 pmEven if you don't, there's always GIMP.http://www.gimp.org/

author: Bored@Work
author_rank: Super Contributor
timestamp: September 19, 2012, 06:40:59 pm
content: Quote from: Chris Wilson on September 19, 2012, 01:20:13 pmHire a dodgy "PCB cloning", "PCB reverse engineering" company from China.
Copy clipboard with remote desktop between Windows and Raspberry - Page 1
Forum section: electronics / projects

author: luiHS
author_rank: Frequent Contributor
timestamp: June 12, 2019, 06:05:46 pm
content: Hello.I need to be able to copy data from the Windows clipboard to a Raspberry connected to the Remote Desktop, but it does not work for me. I read that on Windows, the rdpclip.exe program must be running, I have already started it and it still does not work.In Windows I have tested with MobaXterm and Remote Desktop Connection, it does not work for either of them. In both I have activated the option for the clipboard. I have tried with Putty by SSH, and the clipboard works perfectly, but I need it with a Remote Desktop.What could be the problem with the Remote Desktop ?. Attached screenshots of the configuration of remote desktop programs and the list of windows processes, where we can see the rdpclip.exe program running
Copy impedance controlled track to mechanical layer  - Page 1
Forum section: electronics / projects

author: mrburnzie
author_rank: Regular Contributor
timestamp: November 21, 2022, 03:18:47 pm
content: Hi!I have an impedance controlled track with length tuning in my Altium project.I have two layers, which I use to mark precisely my tracks that need to be impedance controlled for my manufacturer. I also use those layers to write down the values of the impedances I want.What I didn't figure out in Altium is how do I copy paste the track WITH the length tuning onto the mechanical layer (I use a mechanical layer for showcasing the impedance tracks).When I select it all, I can't change to mechanical layers, only when I delete the length tuning. Manually doing this work would require too much time.Any thoughts?Thanks!Edit: Oh cool, my 5th post!

author: ConKbot
author_rank: Super Contributor
timestamp: November 21, 2022, 08:25:45 pm
content: Does the manufacturer need that specific of a callout? I think the CAM operator can figure out the track matching shape and position other than the added length matching is the one that needs to be controlled.Alternatively, make all the controlled impedance traces a specific width. I.e. of your TX line is 8mils wide, make sure there are no other 8 mil traces(bump them up or down) and specify "all traces x width, controlled impedance, z ohms"But to answer your question directly, copy-paste onto the same layer, convert the pasted tracks and length matching to primitives to make the length matching not be length matching anymore, then move to your mech layer.

author: JeremyLeaf
author_rank: Newbie
timestamp: November 21, 2022, 08:31:21 pm
content: From my experience a documentation layer is sufficient with arrows pointing at the impedance controlled tracks. I also include annotated screenshots of the tracks in my PCB specification document.
Copying Rooms in Altium designer  - Page 1
Forum section: electronics / projects

author: HoRRiFiC
author_rank: Newbie
timestamp: March 02, 2016, 05:31:57 pm
content: HeyI am making a small project in Altium designer where I need to make two identical channels, and I have made two Rooms. But when I use the Copy Room function, the components on the bottom layer somehow splits into two parts, the footprint is on the bottom but the silkscreen is on the top side?I think it is related to Embedded Properties (Flipped on layer) because this puts it back on the right layer but the Designator is not placed correctly.I hope some of you have seen this problem before, and know how to fix itAny help will be greatly appreciated.
Cordless drill battery pack cell upgrade  - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: March 25, 2020, 11:57:25 pm
content: I'd like to upgrade the cells in my Bosch's cordless drill battery as they are originally rated at 1.3 Ah but according to my electronic load they are around 1.05 Ah today. (10 year old batteries).I got frustrated today as I was drilling 4 deep holes in a concrete wall and had to swap the battery out after just two holes!Today's high end 18650s are around 3400-3500 mAh as battery tech has gotten much better over the last decade so I thought it would be a fun and beneficial project to take the pack appart and upgrade the cells within.The only issue is, the original ones are Samsung INR18650-13Q and according to the datasheet, they are rated at a max continuous discharge rate of 15A while the ones I'm thinking of replacing them with are Panasonic NCR18650B with a max continuous discharge rate of 6.8 A only.Not sure why this is the case but will this be an issue? I don't want to run out of power while drilling deep holes in concrete with hammer action so should I look at another cell that at least matches the 15A rating of the original battery?

author: Monkeh
author_rank: Super Contributor
timestamp: March 26, 2020, 12:12:05 am
content: You definitely want to get appropriate cells - the ones you're looking at are aimed at lower power applications. 2.5Ah is probably the limit for appropriate cells.You might find it better to just buy a new battery.

author: wraper
author_rank: Unknown
timestamp: March 26, 2020, 12:19:41 am
content: There are some higher capacity high discharge current cells like INR18650-30Q, ICR18650HG2

author: wraper
author_rank: Unknown
timestamp: March 26, 2020, 12:24:04 am
content: Note that soldering those batteries is a bad idea, especially soldering bottom side. It may cause battery degradation or even explosion/fire in the worst case. You should either spot weld them or buy batteries with spot welded tabs already present, then solder to those tabs.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: March 26, 2020, 12:40:25 am
content: Quote from: wraper on March 26, 2020, 12:24:04 amI always assumed that higher capacity battery also come with a higher discharge rate as well.That's obviuosly not the case and thanks for clearing that up.Those look like excellent contenders thanks.Don't worry, I have experience tab welding battery banks so that shouldnt be an issue. Need 0.3 mm nickel strips though as the ones I have are only 0.15 mm which makes sense for the high current draw.
Cordless vacuum conversion to Li-ion - Page 1
Forum section: electronics / projects

author: passengert78
author_rank: Newbie
timestamp: September 25, 2022, 01:30:36 pm
content: Hello!I have an old Sencor cordless vacuum, which operated with NiMH batteries, but they're long dead. I managed to salvage a few laptop batteries (tested them, they still work fine), and decided to convert it into a Li-Ion battery based device. The vacum has a 7.2V DC motor, and I've measured it with my lab bench PSU, that it draws about 3.6A current with 7.2 Volts, and about 4.4A with 8.4 Volts. So, regarding the battery cells, I've decided to use a 2S2P configuration, with a 20A BMS module (a quite standard one: HW-391, according to its specs, it can handle a starting current of 25 amps). I've read somewhere, that since these DC motors are considered as inductive loads, they might have a starting current of approximately 2-3 times that of their normal operation. According to my measurements, that would be around 12-13 Amps.I've tested my battery pack with the motor, and without the BMS it worked fine. However, when I connect the BMS, the motor refuses to start. It spins up for about a second, then some kind of BMS feature (overcurrent protection?) kicks in, and it stops.I'm absolutely sure, that this must be some overcurrent or overvoltage protection issue, since I did some experimenting: I connected the motor's leads to my lab bench PSU, and "jump started" the motor, then turned the PSU output off, and quickly turned the vacuum's switch on, whlile the motor was yet running down, and the motor spun up again, already running from the battery.Buying a new BMS is not an option, and I would prefer not to modify it in any way. It seems, the best option would be to build (or buy) some sort of soft starter. I'm not too experienced in this and started to look for some circuits that solve specifically this BMS problem, but I only found some quite general solutions for soft starting a motor. Does anyone have an idea what would be the optimal solution for soft starting a motor driven by a baterry pack with BMS on it?Thanks in advance!

author: tooki
author_rank: Super Contributor
timestamp: September 25, 2022, 01:54:54 pm
content: Do you have an oscilloscope? If so, look at the output of the BMS while the motor runs. Motors often cause inductive spikes, and maybe those peak at voltages high enough to make the BMS shut down. If so, put a capacitor across the output to smooth the spikes.

author: passengert78
author_rank: Newbie
timestamp: September 25, 2022, 04:04:32 pm
content: Unfortunately I don't have one (yet). To be precise, I have a DSO 150, but that's a toy compared to the normal ones, and I don't think it's capable for this task.I've seen ceramic capacitors in parallel with DC motor poles in hairdrier motors, but they usually come with very simple diode bridges to rectify AC, and I always thought they were there to smooth out the AC wave, not against spikes. But maybe both.However, it may work, but without the oscilloscope, how should I determine the capacitor type and values? Is there a "rule of thumb" to calculate for a 7.2V 3.6A motor?
CORDLESS VACUUM POWER FAULT - Page 1
Forum section: electronics / projects

author: Adamitch3
author_rank: Newbie
timestamp: January 18, 2024, 11:19:18 pm
content: Hi all !New to the forum, very amateur and don't know any electronics experts personally so I need your help please....Several years ago my wife bought a GTECH K9 Multi, cordless vacuum cleaner (type AR2, model AR30) that very quickly failed - on pressing the "go" switch the led light strip illuminates for a millisecond then the 4 battery indicator lights all blink red simultaneously 10 times then reset. There is no sound and motor doesn't turn. GTECH kindly provided a new base unit (less filter box and battery) without quibble, which has worked very well (and hard) but is now getting tired (on/off switch needs replacing and wheels are falling off) !So I am trying to resurrect the original base unit which, if we can fix the fault, is as good as new !?The battery charges and works fine in the (ageing) working unit (4 green lights) so I presume it is OK ?By my untrained eye it looks like the .1uA capacitor wired across the back of the motor may have blown - no continuity across it while still soldered in situ, but there is on my older working unit ?! Not sure if this is a valid test ?Would this cause my fault ? Can I bridge it to test if power would then get to the motor ?Hoping someone has come across this fault before - help to fix would be most welcome.

author: MathWizard
author_rank: Super Contributor
timestamp: October 02, 2025, 11:18:27 pm
content: I llokedat pic's of the GTECH K9, what is the base part ? Is it the battery pack and maybe a circuit board? Or is it the charger, and you plug the battery into it ?? What do the batteries read out of circuit?So only have 1 vacuum but do you have 2 motors now ? Some pictures would help.There can't be much to these circuits, so it should be fixable whatever the issue.What resistance do you measure between the motor terminals, it should be way lower than any cap resistance. What about any diodes.
core materials for signal filters - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: December 12, 2024, 08:51:47 pm
content: If you are interested in signal filters and rather uncommon inductor circuitsWhat ferrite materials are useful for cores that have good parameters for handling signals (i.e. controlled impedance).There is some new technologies like metglas, or nanocrystaline and other less common magentic materials marketed towards PSU filtering. Are these relevant to things like say building RLC filter for things like noise measurement circuits or maybe even op amp inductor experiments?
Correct method to bypass relay?  (pictures inside; re: Sonoff POW R2) - Page 1
Forum section: electronics / projects

author: sofakng
author_rank: Regular Contributor
timestamp: May 10, 2019, 12:52:15 pm
content: I've purchased a Sonoff POW R2 (Wi-Fi switch and electricity usage monitor) but I only want to use it to monitor voltage/amps. The problem is that if the software in the relay crashes or reboots then the relay switches off and on which kills power to my server, etc.Here is the PCB for switch:Here is how somebody bypassed the relay:...and it came from here:http://www.linuxmediaserver.net/howto/performing-your-home-electricity-consumption-audit/Does this look correct and safe?I want to keep the electricity/energy monitoring, but always keep the relay active/powered so it will never turn off.
Correct methods for wiring up a Panel Mount C14 Male Plug - Page 1
Forum section: electronics / projects

author: Krumm
author_rank: Contributor
timestamp: February 07, 2019, 01:16:18 pm
content: Hello,I have a C14 Male Plug that is panel mountable, the reverse of the plug looks like this:https://i.ebayimg.com/images/g/pBsAAOSwpP9Y5fVY/s-l1600.jpg. However, I'm not certain of the best way to connect the wires to this? I could solder however the shape and the holes in the flanges would indicate another way which would be more preferable. What is the best practice approach here?Thank you!

author: Monkeh
author_rank: Super Contributor
timestamp: February 07, 2019, 01:19:24 pm
content: Those are for soldering.Tin the wire, pass it through and bend it back on itself, solder.

author: Gyro
author_rank: Super Contributor
timestamp: February 07, 2019, 01:22:41 pm
content: ... and sleeve! Preferably heatshrink.

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: February 07, 2019, 01:26:47 pm
content: Quote from: Monkeh on February 07, 2019, 01:19:24 pmI would instead just pre tin the wires and the holes, heat the solder on the holes, insert the wire, let the solder flow and combine, done. No folding over of the wire, except you enjoy burnt plastic and blisters on your fingers if you try to unwrap those things a later time because you decided to wire that receptacle an other way than you first intended.Also, consider adding heatshrink tubing over the solder connections to insulate it a bit.

author: Ian.M
author_rank: Super Contributor
timestamp: February 07, 2019, 01:37:15 pm
content: You should always fold the wire over through the eye in the terminal so it cant come off and flop around inside the equipment if the terminal is overheated to the melting point of solder by a C13 cord with poor contacts. Yes its a PITA if you need to rewire it, and its generally nessercery to cut away as much wire and solder from the terminal as possible with sharp side cutters, before desoldering and sucking the hole clear.

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: February 07, 2019, 01:55:36 pm
content: I must admit that I have never thought about (but also never had) the problem that wires could potentially come loose due to an overheating plug. I would assume that you would notice that way earlier by the smell of warm plastics or a burnt out fuse.

author: Krumm
author_rank: Contributor
timestamp: February 07, 2019, 03:16:04 pm
content: Thanks all!

author: stj
author_rank: Super Contributor
timestamp: February 07, 2019, 09:07:31 pm
content: those terminals are actually dal-use, you can use insulated crimp-terminals.if you use solder, put a connector in to it first to act as a bit of a heatsink.i'v seen those type of connectors with pins that moved slightly while soldering because of the plastic melting.
Correct polarity of Rohm YFZ diode? - Page 1
Forum section: electronics / projects

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: March 01, 2020, 11:59:41 am
content: I created a footprint and component in Diptrace for the Rohm YFZVFHTR5.6B Zener diode but the 3D model that was linked from the Rohm web site for this part seems to contradict thedrawings in the datasheet.The 3D CAD .step file (to be fair, Rohm says it's from an outside source) shows that the cathode marking on the top of the device corresponds to thesmallerof the 2 pads under the diode. However, the annotated picture I show below gives my interpretation of the drawings which indicates that the cathode is thelargerof the 2 pads on the underside of the diode; which one is right?I can't order my PCB until I'm sure which way round it is although I strongly suspect that the cathode is the larger pad; I do have some parts on order but hoped maybe someone here could help.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: March 08, 2020, 11:37:30 am
content: Answering my own question. The part arrived and my picture above is correct, the larger of the 2 pads is the cathode. The 3D model shows a dot, which I assumed was intended as the cathode marker, on the top side of the device but it's at the anode end, i.e. it corresponds to the smaller of the 2 pads. So the 3D model is wrong.

author: Siwastaja
author_rank: Super Contributor
timestamp: March 08, 2020, 01:56:43 pm
content: Rule of thumb: in case of discrepancy, 3D models are almost always wrong. Their significance is still underestimated, and they are still treated as "entertainment" by the manufacturers, hence, creating the models is left for some summer trainee (if the model is available at all).

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: March 08, 2020, 03:18:45 pm
content: Quote from: Siwastaja on March 08, 2020, 01:56:43 pmGreat comment, thanks
Correct usage of optoisolator for noise immunity on unshielded connections - Page 1
Forum section: electronics / projects

author: daxliniere
author_rank: Regular Contributor
timestamp: March 03, 2022, 04:18:43 pm
content: Hi everyone,I have a small CNC machine and the limit switches (normally closed) are getting false triggers from the stepper motor wires that run inside the same cable trunking. None of the wires are shielded of course.What's the best way to filter this noise? Current controller is an Arduino GRBL shield. Another controller is on its way, but I would like to solve this induced noise problem.My first thought was an optoisolator, but as far as I can tell, I would need to add a completely separated power supply otherwise there would be a shared ground connection - that would negate the point of an optoisolator, right?Otherwise, perhaps I could add a capacitor (value? series/parallel?) to filter the input? Since it's just a 5v DC on/off signal coming from the limit switches, maybe this could work, too?Any help would be greatly appreciated!All the best,Dax Liniere.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 04, 2022, 02:13:01 pm
content: Try putting a 10n Cap across the limit switch to bypass RFI.
Cossor 1039M oscillograph - a quick and dirty teardown - Page 1
Forum section: electronics / projects

author: intabits
author_rank: Frequent Contributor
timestamp: April 14, 2019, 03:46:31 pm
content: A quick look at this Cossor 1039M oscillograph (England, 1952) that I picked up a while ago at a garage sale.Seehttps://imgur.com/a/B26KJRofor captions to the images aboveIt's very nicely made, and I think worthy of a restoration effort (including recapping, etc).I'll try to get onto that in the not too distant future...

author: hexreader
author_rank: Frequent Contributor
timestamp: April 14, 2019, 04:19:23 pm
content: An interesting historical artefact indeed. Looks cool in those pictures. I cannot believe how clean it looks.Once recapped, I would worry that most of the history will be lost, and you will have gained a truly terrible oscilloscope.As an oscilloscope it is worth nothing, but as a piece of history it is priceless..... unless you can re-cap with genuine vintage replacements?If it were mine, I would leave the cover off, put it in a glass case and never power it up.Just my crazy random thoughts - feel free to ignoreI remember playing with one of these at School 43 years ago - and it was old and horrible to use even then. The wax capacitors and white-body 10% resistors bring a tear to my eye though.

author: intabits
author_rank: Frequent Contributor
timestamp: April 14, 2019, 04:56:15 pm
content: You make very good points.I would love to get it going, but as you describe, I'd then have a crap CRO, with much of its appeal lost.I hadn't considered that, being too eager to just see a trace on the screen.I think I'll probably not ignore your post, and just clean this thing up a bit. (Not sure about a glass case, though.)And then I also don't have to consider the selenium issues.Thanks for the reality check!(There's lots of other junk around here that I could be directing my energies towards instead...)
Cost effectiveness of conductive ink printing on PTFE  - Page 1
Forum section: electronics / projects

author: SreejitS
author_rank: Contributor
timestamp: February 16, 2017, 09:29:22 am
content: Hello all!!I am working on a project which requires multiple LC-tank circuits on PCB of approximately 40cm x 40cm resonating at 1MHz. I wanted to know whether it is cost effective to go for conductive ink screen printing process on plastic sheet as they do with keyboards. Are there any technical caveats that i should be aware of before jumping into them.I am talking about circuits like shown below :http://image.made-in-china.com/43f34j00jZSEFKhywPqH/Keyboard-Flexible-Printed-Printing-FPC-Circuit-Board.jpg

author: CM800
author_rank: Frequent Contributor
timestamp: February 16, 2017, 09:32:26 am
content: I'd have some quality concerns, It makes more sense in my mind to etch, you'd get much finer quality.you can conductively coat nigh-anything, then etch it.Is there any reason you can't use a standard PCB?

author: SreejitS
author_rank: Contributor
timestamp: February 16, 2017, 09:52:51 am
content: Quote from: CM800 on February 16, 2017, 09:32:26 amNo, I can use a standard PCB. I want to know if the alternative option is cost effective or not.

author: CM800
author_rank: Frequent Contributor
timestamp: February 16, 2017, 10:01:50 am
content: I suppose a good question would be how many are you gonna be using per year?I'd say PCB will be hard to beat, the competition between pcb manufacturers is quite big and the market-base is much larger then any other method.

author: Ian.M
author_rank: Super Contributor
timestamp: February 16, 2017, 10:16:36 am
content: There's two other issues here:1. Its *VERY* difficult to get anything to stick reliably to a PTFE surface, so the conductive ink is likely to flake off.2. Conducive inks have a significantly higher resistivity than pure copper or silver, so the tank circuits will have lower Q.Why would you even want a PTFE substrate at 1MHz? Even SRBP is fine at such a low RF frequency.
COTO REED relay quality? - Page 1
Forum section: electronics / projects

author: ViewPoint
author_rank: Newbie
timestamp: May 26, 2015, 05:49:28 pm
content: COTO REED relay qualityHi guys,I am planing to use this reed relays in one of my projects.http://cotorelay.com/wp-content/uploads/2014/09/9007_series_reed_relay_datasheet.pdfIn essence i will measure voltage drop on resistor in series with the relay.But, signals will go up to 1MHz (sine) and i am not sure what is the frequency performance of this type of relays i.e no experiance with them or with this brand.Regards

author: SArepairman
author_rank: Frequent Contributor
timestamp: May 26, 2015, 05:53:37 pm
content: Look at the open capacitance in order to determine how it will perform at 1MHz, as a parasitic AC coupling, coto relays have it specifiedyou should be fine at 1MHz other then the open capacitance, even digi switches are good to quite a few MHz, mechanical will be even better.

author: c4757p
author_rank: Super Contributor
timestamp: May 26, 2015, 05:57:06 pm
content: Compared to a reed relay, layout capacitance will easily dominate, unless you're being waaay more careful than 1 MHz typically warrants.

author: TimFox
author_rank: Super Contributor
timestamp: May 26, 2015, 06:03:41 pm
content: The coil protection diode is listed as optional, but it is very common. If you have a relay with that diode, be careful about the coil polarity. Many reed relay patterns (both SIP as in your data sheet, or DIP) allow for 180 degree rotation of the case, but that will reverse the coil connections.

author: dom0
author_rank: Super Contributor
timestamp: May 26, 2015, 06:30:27 pm
content: QuoteExcellent.Next!

author: SeanB
author_rank: Super Contributor
timestamp: May 26, 2015, 06:32:40 pm
content: 1.4pF capacitance to coil will be fine up to around 100MHz, where the reactance will start to be noticeable. At 1MHz and with impedances under 10k you will not notice it.

author: retrolefty
author_rank: Super Contributor
timestamp: May 26, 2015, 06:43:22 pm
content: Not sure of what you are asking. If you are asking can you operate this relay coil at 1 MHz then I think not. The operate times (.5 msec) and release time (.2 msec) specifications would seem to limit it to around 500 kHz maximum until contact bounce becomes the dominate limit?Edit:Also running the relay coil at 1 MHz would exceed the mechanical life expectancy to around 100 seconds of use?Quote

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 26, 2015, 10:21:58 pm
content: Signal impedance?

author: free_electron
author_rank: Super Contributor
timestamp: May 26, 2015, 10:58:53 pm
content: coto's are second best only to teledyne relays ..

author: ViewPoint
author_rank: Newbie
timestamp: June 01, 2015, 07:31:32 pm
content: Hi guys,Tnx.retrolefty:Not for 1MHz switching.Regards
Could a HT1632 drive 9 5x7 displays? - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: April 12, 2019, 02:29:55 pm
content: It can be configured for 24x16 mode. One more column 25x16 would have made it easier! With 5x7 displays, this makes an easy 4 wide 2 tall arrangement for 8 characters. Is there some easy way to fit a 9th character in? The height is only 7 on the displays, so ROW7 and ROW15 are unused. Also COL20-23 are unused. Any ideas?
Could anyone help me with getting some information that I need - Page 1
Forum section: electronics / projects

author: John Owens
author_rank: Newbie
timestamp: July 07, 2014, 01:15:44 pm
content: Hello there everyone, I am new to the forum and have a question that I could use some help with, first of all I had sent a E-mail along to Dave and you all know the story he could not answer my question because it would take up too much of his time, and he told me that I should ask it here. So here is a cut and paste of the original e=mail that I had sent to him.I was wondering if you might be able to tell me what this is and how I might be able to build it. I have this review that has been done by this person and you can get a decent look at what is inside.If you would could you please take a look at it and possibly you could give me some ideas or maybe you might even be able to come up with a better design. I must tell you that I have no electronics engineering background at all, but I do love to tinker with things on my own, if I could just find out how it is made then I might be willing to try and build it on my own. And I love your vlog on YouTube. I have been watching all of them starting from the very beginning, I just wish that I wasn't so old, not really that old, But I just wish I would have been interested in electronics from a very young age, I find it all very interesting and like I said before I love tinkering and taking things apart to see how it is made. So if possible could you please help me out on this one. Thanks from a friend in the States. Once again here is the video containing what I would like everyone to look at and help me tell what parts are inside and or how I could make one just as simply as the original person had done.>>http://youtu.be/XgnOdo1NEIc> John Owens

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 07, 2014, 02:12:56 pm
content: The meter is a simple LCD voltmeter:http://www.ebay.com/itm/131233968094The other pcb is a voltage generator built on a piece of veroboard.The voltage up button powers the voltage generator by connecting the AA cell to it and charges the capacitor (the big black thing across the connectors). The voltage down button discharges the capacitor by putting a 5K6 resistor across it.That's all there is, google for a voltage generator (100-200v? I don't know) or take an old protocamera with built in flasher apart and you are done.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: July 07, 2014, 02:21:42 pm
content: Safety first !
Could I get some advice on connecting an Arduino data pin to an IR IN plug - Page 1
Forum section: electronics / projects

author: Justin_
author_rank: Newbie
timestamp: December 01, 2018, 10:58:35 pm
content: Hey guys, I have a device with an IR IN 3.5mm jack for an external infrared receiver that I want to connect to an Arduino and control with a remote library, like the one from Adafruit. I've been trying to find out how I would connect it together, but haven't found too much online. Is it possible to connect the Arduino data pin directly to the data line on the IR IN jack, would I need to have an opto between the Arduino and the IR IN port, or is there something else I would need to do?Thanks
Could someone help Identify this connector pls? - Page 1
Forum section: electronics / projects

author: Sweet_Victory
author_rank: Newbie
timestamp: June 18, 2023, 06:08:42 pm
content: It is the mains input to a 24V PSU.

author: Uunoctium
author_rank: Frequent Contributor
timestamp: June 18, 2023, 07:28:48 pm
content: https://www.mouser.de/ProductDetail/Molex/50-84-1035?qs=qjii0NTOo%252B5cXmMI%252BqMCOw%3D%3Dyou have to order contacts separate
Could the entire earth be used as a VLF, ELF, TLF antenna  - Page 1
Forum section: electronics / projects

author: skyler
author_rank: Regular Contributor
timestamp: January 06, 2014, 03:20:43 am
content: So maybe to communicate with aliens, we should use the entire earth as antenna.I'm sure the earth resonates at a certain frequency.Would it be possible to use the earth as a tremendously low frequency antenna and use some extremely slow speed code that takes like a day to send a sentence of text and stuff?

author: Rerouter
author_rank: Super Contributor
timestamp: January 06, 2014, 03:31:51 am
content: it is possible, but who would be looking for such a low frequency signal? based on our current expectations, any significantly developed lifeform will trend towards higher data density signals, which tends to end up as high speed analog modulation,though i agree that it could make a difference in one way, as higher frequencies are more likely to be attenuated it could pass through what ever atmosphere could be possibly attenuating their outgoing signals

author: liquibyte
author_rank: Frequent Contributor
timestamp: January 06, 2014, 03:33:11 am
content: Quote from: skyler on January 06, 2014, 03:20:43 amYou need to look up Tesla's work.

author: SArepairman
author_rank: Frequent Contributor
timestamp: January 06, 2014, 03:36:16 am
content: what is TLF?http://en.wikipedia.org/wiki/Terrestrial_stationary_waves\?

author: hiddensoul
author_rank: Regular Contributor
timestamp: January 06, 2014, 03:49:56 am
content: You would need a pretty big PA (Power Amplifier) stage to get our rock to resonate but anyway they are using the hydrogen line. Seehttp://en.wikipedia.org/wiki/Hydrogen_line#Possible_uses_for_SETIfor information on its use in SETI
Could this THT part be replaced with a SMD counterpart? - Page 1
Forum section: electronics / projects

author: Red_Micro
author_rank: Regular Contributor
timestamp: April 09, 2020, 04:25:40 pm
content: I'm looking to replace this resettable fusePTGL09AR390N0B52A0with a SMD equivalent (if possible), but I haven't had success so far. I'm thinking of using 2 lower ratings PTCs in series to get the same rating, but even at 120V it's hard to find them. This is used in a solid state relay as shown. Any suggestion?
could you help me streamline my mobile footwarmers ? - Page 1
Forum section: electronics / projects

author: Ehaze
author_rank: Contributor
timestamp: November 28, 2021, 11:58:48 am
content: Last year I tried to build some foot warmers powered by 20,000 mah anker power banks connected via usb cord from my pocket to the nichron heating wire that was connected to a usb micro board . The idea was to have a simple button switch i could click it on and off throughout the day to replace the heat loss when needed . Nothing fancy , no thermal cutoff or pwm thing to change draw , just simply on and off .One problem i had was one of them would smell smoky , I guess it was shorting or being stressed.They where not very reliable or durable . this year I would like to improve them a bit but getting rid of the usb board . I was thinking heating wire connected to a switch , connected to the battery source but swapping out the usb connectors for xt30s .5vs was more than enough I got about 2 hours out of them , but i think it was drawing more amps than It needed . SO I am wondering if i should stick with my battery banks at 5vs , or build a 4 cell batter in parallel and just run the 3.7ish volts .Im also wondering what kind of BMS does it require and how should I balance charge ? I have a 4 bay charger so i could just use a battery holder and pull the cells , but i still need a protection from over discharge . There are so many little listings on ebay or amazon i dont know which ones to go for . I still get a bit confused about custom batteries , i see some BMSs need balance wires but the small ones I see dont have that .Please let me know what you think i can do to make it reliable and safe , thanks
Could you review regulator stage of bench PSU design - Page 1
Forum section: electronics / projects

author: virinom
author_rank: Newbie
timestamp: August 24, 2020, 09:14:01 pm
content: Hi all,I am designing 0-50V 0-10A CV, CC digital bench power supply. By saying digital I am referring to controlling output transistors with DAC from MCU and setting DAC voltage by reading output values with MCU using ADC.I started with power stage. In Multisim simulation, I used a potentiometer instead of DAC and I don't have ADC stage. I'm planning to use MJ15003 in circuit but I used MJ15024G for simulation. Could you please look at my power stage and inform me If there is any major design error or If you have any recommendation.I am putting Multisim link below, you can also find schemetic in attachments.https://www.multisim.com/content/wRrPWn9FGKN44TeTAtQD3h/power-supply/Thank you

author: kallek
author_rank: Regular Contributor
timestamp: August 26, 2020, 07:13:12 pm
content: Hi, and welcome!You need analog feedback from output. Digital feedback is too slow. I also suggest to start with lower voltage and current. Designing that kind of linear power supply is big challenge to everyone.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 28, 2020, 09:45:32 pm
content: 50V 10A is pretty ambitious.A lineair supply would need to be able to dissipate 500W in worse case condition.That is like a big CPU cooler for each of your 4 power transistors.Do you have a good reason for this power requirement?In my experience, I can do most projects with 30V 500mA power supply, and when more power is needed it often does not have to be well regulated.You are also likely to want to have multiple power supplies. So even if you first design / build a small one, then you will still use it after you built the big monster.I also agree with kallek. Use a uC and dac to make a setpoint, and use analog circuitry to regulate the output voltage.

author: dietert1
author_rank: Super Contributor
timestamp: August 28, 2020, 10:14:37 pm
content: There is analog feedback. The U1 gain stage has G = 6, so at 2 V input it outputs 12 V. The Q3/Q2 gain stage has G = 17, so that gives 204 V instead of 50 V. And something is wrong with R7.Regards, Dieter

author: wraper
author_rank: Unknown
timestamp: August 28, 2020, 10:24:42 pm
content: Quote from: dietert1 on August 28, 2020, 10:14:37 pmIt is not a feedback he talks about. Digital feedback is not impossible as such. However not with a regular MCU, nor it would be trivial. Very complicated stuff to implement. Here is simplified linear PSU where you can see the feedback.

author: dietert1
author_rank: Super Contributor
timestamp: August 29, 2020, 03:25:02 am
content: The feedback signal for R6 should be taken from the output of the emitter followers. And R6 should be 3.1666 K.Regards, Dieter
Counterfeit MPU6050 chips from China - Page 1
Forum section: electronics / projects

author: not_crazy
author_rank: Newbie
timestamp: April 26, 2019, 05:08:51 pm
content: Hi everyone, how are you? I hope fine.Several weeks ago I bought some MPU6050 modules, the typical GY-521 module, from China (Aliexpress) .Yesterday I've received it, and then I tested all of them with an Arduino one board, using the "MPU6050_6Axis_MotionApps20" library, created by Jeff Rowberg. I found that of the 9 modules tested, only 3 of them was working as expected. Five of them were not being initialized correctly and were working really weird (absolutely useless). One of them was correctly initialized, but also working really weird.Then I modified the library to show the "WHO AM I" register of the modules. The MPU6050 that were working as expected, show a value of 0x68 (as especified in datasheet). The MPU6050 that were not being initialized correctly and working weird, shown a strange value of 0x72. The MPU6050 that were initialized correctly and works weird, show a value of 0x68. I decided to visually inspect all of the modules, with the following, interesting result:I suspect that it is a different chip from invensense and it was remarked as MPU6050. Good try, Aliexpress seller, but I always test all products and take videos of unboxing and testing before rating them. Of course I will open a dispute and got my money back.What do you think about this? Do you have stories about counterfeit products in China that you want to share with us?

author: Miti
author_rank: Super Contributor
timestamp: April 27, 2019, 01:56:20 am
content: Counterfeit electronics from China? No, never heard of it.

author: Miti
author_rank: Super Contributor
timestamp: April 27, 2019, 02:03:04 am
content: Seriously now, there's an entire rant here:https://www.eevblog.com/forum/chat/fake-$9-chinese-intel-8087-chip-from-ebay/

author: imk
author_rank: Regular Contributor
timestamp: March 30, 2022, 10:35:30 pm
content: Hello,I to have had 6050 initialization issues, found it was due to poor rise times on the i2c clk/data buss.So i put an i2c bus isolator chip in to separate off the other i2c device that it was sharing the bus with.imk

author: Kleinstein
author_rank: Super Contributor
timestamp: March 30, 2022, 10:49:41 pm
content: Poor signal quality, e.g. with long cables or too much capacity could cause communication problems. Somewhat partially working is unusual with conterfeit chips of such a type ( get that with OP that are just LM358).With I2C the value of the pull up resistors can make a difference.A picture of a chip with the connecting cable to the Arduino may help to identify problems there.The parts may be low qualtiy, maybe some layout or circuit weakness, but don't look counterfeit.