hybridfree/eevblog-posts huggingface dataset:
how long does it take for a short to damage a circuit board? - Page 1
Forum section: electronics / beginners

author: dinodoody
author_rank: Newbie
timestamp: March 14, 2014, 07:19:18 pm
content: I tryed reballing a GPU for the firs time today. I used hot air to take off the chip and then replace the balls on it. But when I put the chip back on I think the board was warped a little bit and some of the balls got bridged (shorted). I turn on the computer for only 3 seconds and i felt near the chip get really hot so I turn it off. Is 3 seconds enough to ruin things or did i shut it off at the right moment.

author: MatCat
author_rank: Frequent Contributor
timestamp: March 14, 2014, 07:21:32 pm
content: Quote from: dinodoody on March 14, 2014, 07:19:18 pmI have had chips do this and be fine, and others that where not... the only way to know is fix it and test agan.

author: dinodoody
author_rank: Newbie
timestamp: March 14, 2014, 07:37:58 pm
content: This is good to know. I will try again another night, not right now because I am sick of the fumes. I need to use a fan or something and open a window next time.

author: Neilm
author_rank: Super Contributor
timestamp: March 14, 2014, 08:16:54 pm
content: Did it have a heat sink on it before you removed the chip? If so did it have the heat sink on when you powered it up? I killed a processor a few years ago by forgetting the heat sink - it was on for about 5 seconds.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 14, 2014, 09:36:58 pm
content: Depends on what gets shorted. Power to ground? Maybe the power supply is current limited, maybe it's bricked. Power to power -- the wrong way? Probably burned a hole in the substrate. Power backwards into a signal pin? Probably vaporized the pin structure.As for "how long"? A couple microseconds and up. Consider that a switch can be flipped on and off in about 20,000 times longer...Tim

author: dinodoody
author_rank: Newbie
timestamp: March 15, 2014, 10:23:54 pm
content: Quote from: Neilm on March 14, 2014, 08:16:54 pmI had the heatsink on. I'll keep you guys updated and report back if it works or not. This time I figured a way to keep the board from warping, i bolted it down to the preheater with about 1 inch standoff (last time it was just sitting on pieces of hershy-kiss-shaped tinfoil)

author: JuKu
author_rank: Frequent Contributor
timestamp: March 18, 2014, 11:34:16 am
content: How long does it take for a short to damage a circuit board? Anything from a few nanoseconds to several years. In other words, no way to know. But a chip that has heated over spec is not as reliable as it could be anymore. It might work very long, but if reliability is a concern, be concerned.
how make a adjustable ZVS stepup for charge a capacitor bank - Page 1
Forum section: electronics / beginners

author: thedark
author_rank: Newbie
timestamp: June 25, 2023, 12:53:31 am
content: Hi, i want make a adjustable ZVS stepup for charge a capacitor bank, where the capacitor bank is 19000 uF at 450 V dc, and I want to make a high power stepup to charge that capacitor at different voltage and as quickly and economically as possible, some schematic or how I could make one. and the ideal input would be 120 Vac rectified.but no problem if use computer psu. that circuit I want make like that but adjustableor that
How many bits does this audio CODEC has when recording (TI's TLV320AIC3204)? - Page 1
Forum section: electronics / beginners

author: RoGeorge
author_rank: Super Contributor
timestamp: April 22, 2021, 03:38:46 pm
content: The audio CODEC TLV320AIC3204 does not specify in the datasheet the number of bits directly. There are some mentions about 24 bits and 192 kHz in the programming guide, thought not sure if its ADC is capable or not of 24bits/192kHz. The noise figures would rather suggest a 16 bits ADC than a 24 bits one.Here's the docs, what is the max number of bits/sampling rate that this IC is capable, please?- product webpagehttps://www.ti.com/product/TLV320AIC3204?sa=X&ved=2ahUKEwiDm6mnk5LwAhW_AxAIHTvlBe0Q9QF6BAgIEAI- datasheethttps://www.ti.com/lit/ds/symlink/tlv320aic3204.pdf?ts=1619066921525&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTLV320AIC3204- programming guidehttps://www.ti.com/lit/an/slaa404c/slaa404c.pdf?ts=1619066934369I have it on a TI devboard (eZdsp C5535 USB), and would like to use its ADC to measure the distortions from a low THD Wien bridge.Is this CODEC's ADC 24/192 capable or not?

author: Pedro Medeiros
author_rank: Newbie
timestamp: April 22, 2021, 03:45:39 pm
content: Hi, my name is Pedro! I'm starting to use this forum.Spam link removed

author: Simon
author_rank: Unknown
timestamp: April 22, 2021, 07:51:34 pm
content: Quote from: Pedro Medeiros on April 22, 2021, 03:45:39 pmYour name "was" Pedro and you won't be using this forum to spam!

author: BrianHG
author_rank: Super Contributor
timestamp: April 22, 2021, 08:14:56 pm
content: The ADC is only capable of 93db SNR, line 3 in the features in page 1.And this is only with the pre-amp gain set to 0db or less with the minimum amount of distortion while sampling a source signal at ~ -6db, or half amplitude. Yes, sampling the full amplitude reveals additional distortion as seen on figure 25 on page 43.Only use this device for consumer audio, do not expect studio grade performance even if the data bus has more than 16 bits.As for the true bits of the ADC internally itself, it is not specified.
How many inputs can a CMOS BCD output drive? - Page 1
Forum section: electronics / beginners

author: cdreimer
author_rank: Newbie
timestamp: February 28, 2017, 02:19:57 am
content: My 5V circuit uses a 4518 (BCD Up Counter) to 4511 (BCD to 7-Segment Driver). I want to add a 4028 (BCD to Decimal Decoder) to the BCD outputs of the 4518.Does anyone know what the fanout is for a BCD output to BCD inputs? Every BCD circuit design I've looked at has one-to-one relationship between outputs and inputs.This webpage claims that each CMOS output can drive up to 50 inputs.https://electronicsclub.info/cmos.htmOne data sheet for the 4518 claims that the fanout can drive two 74L or one 74LS.http://www.jameco.com/Jameco/Products/ProdDS/13565NSC.pdfI got the 4518/4511 wired up on the breadboard. I haven't added the 4028 to the circuit yet. I'm trying to think this through before I blue smoke another IC.

author: MK14
author_rank: Super Contributor
timestamp: February 28, 2017, 02:42:32 am
content: You will be fine. It (the CMOS output) can handle many CMOS logic inputs.The "74L or one 74LS.", are old logic gate types, which used quite a lot of input current (relatively), hence the low fan out for them.EDIT:The "low fanout" I was referring to, is when a relatively weak CMOS output, tries to drive TTL, such as 74 LS inputs.TTL to TTL has better fan-out.

author: Brumby
author_rank: Unknown
timestamp: February 28, 2017, 02:49:10 am
content: The original 7400 series TTL had a fan out of 10 - for other TTL inputs. The number for CMOS to CMOS is a lot higher.
How many keys in AES? - Page 1
Forum section: electronics / beginners

author: shivajikobardan
author_rank: Contributor
timestamp: August 26, 2022, 08:59:08 am
content: Say we've 16 byte(128 bit) key. So, how many keys would be required?So, imo. 128 bits key would require 10 roundsInitial Round(also called add round key), then 10 rounds(including the last round), so we'd require 11 different keys. Am I correct?

author: pcprogrammer
author_rank: Super Contributor
timestamp: August 26, 2022, 09:24:59 am
content: I think this article explains it.https://en.wikipedia.org/wiki/AES_key_scheduleQuote

author: golden_labels
author_rank: Super Contributor
timestamp: August 26, 2022, 12:58:13 pm
content: While pcprogrammer gave the results, the question remaining is if your logic is right. Yes, it is!SeeFIPS 197, figure 5 (in section 5.1). Appendix A also contains a complete example of deriving all round keys.
How many LEDs can this driver power? - Page 1
Forum section: electronics / beginners

author: Peteb
author_rank: Newbie
timestamp: March 07, 2021, 11:24:18 am
content: Hello, I purchased 5 of these LED lights all with a varying amount of LED boards inside them with the idea of linking them up together and keeping the lights on low in my lounge. Ideally, I would have one controller for all LEDs otherwise simply wiring them up separately will cause them to turn off/ on with the IR remote if it's not at the perfect angle. So what I would like to do is connect further boards together with JST connectors effectively extending the current design to more of the lights. The attached pictures will make more sense.All I can discern from the largest light driver is that has a slightly different output but I’m not quite sure what it means and if anyone can shed light on it? The output is (25-50) X2W. Does this mean 50-100W? I mean that would make most sense considering the light draws around 80W on full power with the 60 LEDs.With the other 4 lights there would be a max of 150W extra requirement.

author: mvs
author_rank: Frequent Contributor
timestamp: March 07, 2021, 01:07:22 pm
content: It is constant current driver, with 2x240mA output. Output voltage depends on number of LEDs in series and can be between 75-170V.Each board has probably two separate strings of 6 LEDs connected in series. 6 LEDs * 5 boards * 3.2V LED forward voltage will give around 100V.If you connect additional 5 boards from the second light, you will be already out of specified voltage range.

author: Peteb
author_rank: Newbie
timestamp: March 07, 2021, 05:20:58 pm
content: Thank you, that's incredibly useful. So if I were to skip the idea of using all 5 lights and went for three of the smaller ones (they have between 2 and 3 LED boards, with each board having 12 LEDs on them) then what would my maximum be? I'm guess it'll be just under 9 boards, 8 to play it safe (170V / 3.2V / 6 (or 12 LEDs across the two outputs?)
How many nFarads is this X2 capacitor? - Page 1
Forum section: electronics / beginners

author: sdancer75
author_rank: Frequent Contributor
timestamp: May 27, 2019, 01:01:52 pm
content: How many nFarads is this X2 capacitor ?

author: wraper
author_rank: Unknown
timestamp: May 27, 2019, 01:06:18 pm
content: 0.1uFhttps://www.tdk-electronics.tdk.com.cn/inf/20/20/db/fc_05/X2_B81130.pdf

author: sdancer75
author_rank: Frequent Contributor
timestamp: May 27, 2019, 01:51:26 pm
content: Quote from: wraper on May 27, 2019, 01:06:18 pmHi,I have already downloaded this but I didn't find this information. As far I can understand from the datasheet it depends on the distance between the two leads to compute the right capacity, Am i wrong? What page to look in this datasheet?

author: PA0PBZ
author_rank: Super Contributor
timestamp: May 27, 2019, 02:04:30 pm
content: It's the μ1 on the second line on the top, page 2 of the pdf explains it (but a bit hidden).Not the most obvious marking I agree...

author: Audioguru
author_rank: Super Contributor
timestamp: May 27, 2019, 02:10:47 pm
content: Why don't they CLEARLY mark its capacitance LIKE EVERY OTHER CAPACITOR MANUFACTURER??

author: sdancer75
author_rank: Frequent Contributor
timestamp: May 27, 2019, 02:24:59 pm
content: Quote from: PA0PBZ on May 27, 2019, 02:04:30 pmSo the μ1 = 0,1μF on the top of the capacitor or it means 1μF?The example inside the datasheet as far as I can understand relates the capacitance with the space of the leads? And where the heck it says that 1μ = 0.1μF ?

author: wraper
author_rank: Unknown
timestamp: May 27, 2019, 02:31:57 pm
content: u1 is not 1u. u1 = 0.1 uF, 1u = 1uFQuoteThey won't describe such simple things you should already know in the datasheet.

author: sdancer75
author_rank: Frequent Contributor
timestamp: May 27, 2019, 02:44:46 pm
content: Quote from: wraper on May 27, 2019, 02:31:57 pmYes, of course, I knew that BUT I thought that it was an internal marking code (I didn't really realize at the begging that this symbol was actually a "u") so my question, in this case, is where should I find a table that this symbol corresponds to a capacitance number!Now it's all clear. Thank you!
How many power supply outputs?  - Page 1
Forum section: electronics / beginners

author: Tech77997
author_rank: Contributor
timestamp: March 18, 2020, 12:39:03 am
content: Hello,I am a beginner and looking to purchase a power supply. I am planning to work on op amps and micro controllers. I have been thinking that three outputs would be best, but of course this is more money. Can I get by with one, single output power supply?Many thanks to you for your insight.

author: WattsThat
author_rank: Frequent Contributor
timestamp: March 18, 2020, 12:47:42 am
content: Multiple posts of the same topic are frowned upon. Please keep a discussion in one thread, starting multiple threads wastes time and patience.https://www.eevblog.com/forum/beginners/is-this-multiple-triple-power-supply-a-good-buy/msg2968870/#msg2968870

author: Tech77997
author_rank: Contributor
timestamp: March 18, 2020, 12:50:02 am
content: You're right I should have asked in there; sorry again.
How memory chips are connected - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: June 10, 2015, 05:42:26 am
content: In a device there are 4 pcs of ELPIDA EDE5116AJBG-LI (32M words × 16 bits) DDR2 SDRAM chip. According to its datasheet, organization of that DDR2 SDRAM chip should be 8M words × 16 bits × 4 banksCPU, used in that device , uses 64-bit DDR2 interface and the total RAM is 256MB.How must be connected those 4 pcs of ELPIDA EDE5116AJBG-LI chips to provide 256 MB RAM capacity?Thanks

author: slateraptor
author_rank: Frequent Contributor
timestamp: June 10, 2015, 06:24:08 am
content: Are you trying to understand the arithmetic of how 4 of these memory devices make 256MB memory, or are you seriously expecting someone to draw you a schematic?

author: John_ITIC
author_rank: Frequent Contributor
timestamp: June 10, 2015, 07:04:43 am
content: Take a look at the various 64-bit wide SODIMM/DIMM specs. Vendor datasheets (Micron and others) also contain information how chips are connected on their DIMMs.https://www.google.com/?gws_rd=ssl#q=sodimm+jedec+spec

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 10, 2015, 09:16:54 am
content: All address lines, all chip selects, all control signals, connected together in common for all chips. All data lines arranged into 4 x parallel buses of 16 bits each, for a total of 64 bits per bus cycle. DDR2 uses SSTL2 signaling which requires controlled impedance traces, minimal stub lengths, matched trace lengths, series and/or stub terminator resistors, and requires low noise (typically all signals are routed over a common plane which is connected to VREF, along with the terminators and a VREF supply controller chip).As far as I know, the 4 pages are combined transparently in the chip design, probably each page being accessed independently, then all four WORDs queued up for the data burst. The DDR2 controller or interface device should be aware of the configuration and transfer signals necessary to use these devices, on its own.Tim

author: Jane
author_rank: Frequent Contributor
timestamp: June 10, 2015, 07:51:59 pm
content: Thank you for the replies.And if DDR2 fails, is there any way how to find out which chip, of those 4 chips, is faulty?

author: Len
author_rank: Frequent Contributor
timestamp: June 10, 2015, 08:26:26 pm
content: Quote from: Jane on June 10, 2015, 07:51:59 pmSometimes the old finger test can tell you, as here:https://youtu.be/UPSLgY_-4HE?t=20m33s

author: amyk
author_rank: Super Contributor
timestamp: June 10, 2015, 08:49:33 pm
content: https://www.jedec.org/standards-documents/focus/memory-module-designs-dimms/DDR2/240-pin%20Unbuffered%20DIMMsSchematics, BOM, and board layouts are there. Need to register but it's free. Look for JESD79-2 also, that's the main DDR2 standard.
How metcal, mx-h1-av hand piece ,sleeping mode works? - Page 1
Forum section: electronics / beginners

author: girolamo
author_rank: Contributor
timestamp: May 08, 2015, 01:59:19 pm
content: HelooI decide to made a power suply for my MX-H1-AV hand piece.In this way i try to understand how works sleeping mode of work stand.Is there anyone who can help me?Thanks

author: girolamo
author_rank: Contributor
timestamp: May 08, 2015, 04:41:55 pm
content: I understand that in workstand is 2 pieces of magnet.What's the use? In handpiece is there a sensor? Hall effect device? Reed device?as far as I know there is none of these components.In that case ,how does it work anyway?

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: May 08, 2015, 04:58:53 pm
content: As the tip regulates its temperature based on Curie temperature and skin effect. A high frequency current is used to heat up a magnetic material through the skin effect. When the Curie temperature is reached, the material loses its magnetic properties. The Skin effect disappears and the material cools down again. And so on. In the end, the temperature slightly wobbles around the Curie temperature of the magnetic material.Now the magnet in the stand influences this regulation loop. There are different opinions how this works exactly: e.g. whether it lowers the Curie temperature directly or saturates the core. Anyway, it's merely based on physics - as it the regulation itself. There is no switch or electronics involved.

author: girolamo
author_rank: Contributor
timestamp: May 08, 2015, 05:42:46 pm
content: Is correct, this is the theory of operation of this type of soldering iron.However where "knows" handpiece that is ' seated" in workstand ,to decrease the power? Simple magnetic field of worstand influences ,or amend the point qurie of tip?

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: May 08, 2015, 05:52:15 pm
content: This is what I wrote in the last paragraph. The magnetic flux of the magnet in the stand influences the tip's regulation loop and thus lowers the temperature.My understanding it that the flux saturates the magnetic material which again reduces the skin effect and leads to less heat.

author: girolamo
author_rank: Contributor
timestamp: May 08, 2015, 06:03:27 pm
content: Thank you for this information! And I am I suspected give now I'm sure that's the way it is! Thank you, and I wish you a lovely day!
How might I test this pass transistor pack? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: March 06, 2020, 12:18:48 pm
content: I had big problems with an elderly Farnell 60V @ 50 Amp linear adjustable bench supply a long time ago and thanks to help here I fixed it. Sadly it went bang the other night again, blowing a 50A internal fuse between the full wave bridge rectifier / smoothing caps and the pass transistor block. I replaced the fuse with a temporary 10 A one and on turn on see over 70V DC at the output, with no voltage control. I believe if a pass transistor was shorted the fuse between the bridge and itself would blow? I attach the schematic of the bridge, I changed all the pass transistors from 2N2055 to MJ15003 about 2 years ago, which have a much higher 120V DC rating, as last time this thing had an uncontrolled output from the bridge it blew some 2N2055's.Note, the input to the bridge is supposed to be controlled via a circuit that uses mark space from the main transformer, the idea being to not have a high drop voltage needed on the pass transistor block. This may have gone berserk but i am not sure if a pass block issue could be feeding the control circuit bum info. So I thought I would try and test it in chunks first seeing if I can use an external supply on the base andwherever on the pass block to see if it will control the output. Then work backwards towards the input of the supply.So how can i externally control the pass block from a separate bench supply? Where to connect what to DISconnect, and what voltage to apply?Many thanks!

author: David Hess
author_rank: Super Contributor
timestamp: March 07, 2020, 12:10:32 am
content: Quote from: Chris Wilson on March 06, 2020, 12:18:48 pmFailures are usually related to excessive junction temperature from excessive junction-to-ambient thermal resistance (lack of cooling) or secondary breakdown related which is quite possible in a 60 volt power supply. Just increasing the Vce breakdown voltage of the transistors does not necessarily improve either.With that said, the MJ15003 is probably the best transistor in this application for the price.
How much ac leakage across a transformer is normal? - Page 1
Forum section: electronics / beginners

author: CoolJosh3k
author_rank: Newbie
timestamp: May 01, 2017, 01:24:59 pm
content: So I noticed when I hold onto the metal frame of my lamp, whilst I touch the side of my hairy arm against the metal base of my microphone, there is some electrical continuity.I confirmed it to be my lamp with a multimeter between it's metal frame and my kitchen sink. It shows AC with around 400 to 600 micro amps.Before I call my lamp faulty and bin it, how much ac should normally appear like this? Is this nothing to worry about at all?Thanks for any help.

author: Jeroen3
author_rank: Super Contributor
timestamp: May 01, 2017, 01:29:50 pm
content: For a real transformer that is too much.For a switchmode supply that is normal.Generally below 1 mA is allowed. See local regulations.

author: CoolJosh3k
author_rank: Newbie
timestamp: May 01, 2017, 01:42:45 pm
content: Ah, thanks. Nothing to worry about then if I ever get tickled like that.As a follow up question...Why is it more strict for a normal (linear?) transformer?

author: helius
author_rank: Super Contributor
timestamp: May 01, 2017, 02:13:15 pm
content: Switchmode PSUs contain EMI suppression capacitors that couple some of the input AC to the case. When the case is earthed, it travels to earth. When it isn't, you can sometimes feel the current passing through your body. 1 mA is approximately the threshold of sensation—20 mA and above could be dangerous. Some countries place the safety limit at around 400 uA, but the regulations for different types of equipment differ.

author: CoolJosh3k
author_rank: Newbie
timestamp: May 01, 2017, 03:00:09 pm
content: Where would one find local regulations?What is the proper way to read the current? I figure chassis to sink is not too typical.

author: Gyro
author_rank: Super Contributor
timestamp: May 01, 2017, 03:51:44 pm
content: QuoteThat's where setting your country flag in your profile comes in really handy.If you're in a country that requires proper grounding of all plumbed fitting then chassis to sink, radiator etc is really quite appropriate.P.S. If doing this sort of test, then it's a good idea to be cautious and insert some sort of safety series resistor in series with your meter, untill you've established that it is just leakage current and not a situation where the chassis reallyisLive. It might save you a meter fuse, nasty flash, or much worse (depending on the quality of the meter).

author: Zero999
author_rank: Super Contributor
timestamp: May 01, 2017, 06:22:32 pm
content: Quote from: CoolJosh3k on May 01, 2017, 01:42:45 pmIt isn't more strict for a real transformer. It's just switched mode power supplies tend to be more leaky because of the Y capacitor.

author: CoolJosh3k
author_rank: Newbie
timestamp: May 02, 2017, 07:47:42 pm
content: I have updated my profile.
how much current do I need to drive the grid for a 6v6gc tube? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: January 27, 2020, 01:27:00 am
content: specifically 4 6v6gc tubes.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 27, 2020, 02:32:48 am
content: In what class, and to what bandwidth?Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 27, 2020, 02:43:49 am
content: What would you be switching that would give any advantage between those two cases?Class 2 operation typically needs a drive transformer, or cathode followers, to avoid distortion from the nonlinear current draw. There's very little benefit to running 6V6 in class 2, and doing so is a huge bother, so it's basically never done.Tim

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 27, 2020, 03:28:32 am
content: My trusted old RCA Receiving Tube Manual, lists the grid 2 current at maximum signal from 4 and 7 mA, with a plate voltage of 180 and 250 volts respectively, operating class A1 and connected as a pentode.With no signal, it drops to 3 and 4.5 mA with 180 and 250 volts respectively.It doesn’t show any grid 2 current when connected as a triode.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 27, 2020, 05:47:17 am
content: Yeah, screen grid doesn't count for amp class when it's connected to the plate circuit.I guess Gomes is a SEPP configuration (ref: TubeCAD article), not really amenable to class AB operation. Is that really what you're looking at?Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 28, 2020, 12:59:18 am
content: Oh man, that circuit has so many things wrong with it...Such is par for the course in tubophile land.Tim

author: langwadt
author_rank: Super Contributor
timestamp: January 28, 2020, 01:25:45 am
content: might consider a bit more learning before you start playing with something quite as deadly ...

author: Johnny10
author_rank: Frequent Contributor
timestamp: January 28, 2020, 02:36:35 am
content: I don't get it?
How much efficiency is lost in a solar panel if you were to use a 2 stage clear? - Page 1
Forum section: electronics / beginners

author: TT_Vert
author_rank: Regular Contributor
timestamp: June 03, 2022, 07:28:44 pm
content: Basically I have some cheaper LED lights w/ solar charging tops that highly oxidize due to UV rays and I feel it has to inhibit charging. I have buffed the plastic and would like to put an automotive clear i have left over from a project some time ago over it to prevent UV degradation. Will this severely impact the output of the solar panels themselves?ThanksDave

author: bdunham7
author_rank: Super Contributor
timestamp: June 03, 2022, 08:25:49 pm
content: Probably not. The majority of the energy is in the visible and near infrared spectrum and clearcoat should let that through just fine.

author: TT_Vert
author_rank: Regular Contributor
timestamp: June 16, 2022, 01:03:52 am
content: Quote from: bdunham7 on June 03, 2022, 08:25:49 pmYeah they've been fine w/ the clear so i'm happy about that.Dave
How much headroom is best when choosing a PSU? - Page 1
Forum section: electronics / beginners

author: eug
author_rank: Contributor
timestamp: July 30, 2015, 05:33:28 am
content: Hi everyone,I'm looking at replacing a power supply for two sets of three LED strips.Each strip takes about ~4.2A at 12V. The original lighting company used one generic no-name 12V 12.5A LED driver for each strip. They're constant current constant voltage drivers so they're just regular PSUs. I'm assuming the strips have current limiting resistors built in. Three of the six drivers have died (!), so I'm looking for a replacement.One annoying problem the old drivers have is, when the power is switched off, the LED strips flash a few times before turning completely off. I'm guessing that's related to having too-low a load on the PSU? The lighting circuit isn't dimmed. It also happens when the drivers are plugged directly in to a GPO and switched off.I'm now looking at getting replacement drivers. Instead of getting one PSU per strip I'm planning to get two higher-current PSUs powering three strips each (the strips are on opposite sides of a hall).I'm deciding between the MeanWell HLG-320H-12 (12V 22A) and the HLG-240H-12 (12V 16A).The 22A one would be running just under 60% load and the 16A one just under 80%.In theory the one that runs cooler should last longer. Is that the case in real life?I'm also a little concerned that I'll still have the flashing-when-switched-off problem with the 22A PSU.Any suggestions?Thanks!http://www.meanwellaustralia.com.au/products/hlg-320hhttp://www.meanwellaustralia.com.au/products/hlg-240h
How much is used Tektronix 2225 worth? - Page 1
Forum section: electronics / beginners

author: cavlovic
author_rank: Contributor
timestamp: October 15, 2013, 12:35:10 pm
content: I just found a listing of Tektronix 2225 scope, that looks to be in good condition and comes with one probe. Shipping is also reasonable to my country. I would like to buy it and was wondering how much you guys think it is worth because I really have no idea?It is this one:http://www.ebay.co.uk/itm/200973478488?ssPageName=STRK:MEBIDX:IT&_trksid=p3984.m1426.l2649Thank you!

author: BravoV
author_rank: Super Contributor
timestamp: October 15, 2013, 12:45:20 pm
content: I think different people will have different value, but for me, max at $100, and also it must be in good shape and guaranteed working.Btw, at eBay, the popular Tek 2465B 400Mhz is hovering with offering prices about $350 to $400, I think this a fair base price for comparison with 2225, imho.Btw, that item at the crt bezel has few cracked or chipped parts, watch closely at the photo.
How much is ZI,RW,RO & Code in arduino - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: July 09, 2017, 07:21:50 am
content: 1. I am using Arduino 1.8.1 & made a code in it. Board it Atemga2560 R3.2. Final code size is:a) 674 bytes (8%) of dynamic memory, leaving 7518 bytes for local variables. Maximum is 8192 bytesb) 22440 bytes (8%) of program storage space. Maximum is 253952 bytes.3. How to get below in arduino:a) Zero Initialize (ZI) or .bssb) Read Write (RW) or .datac) Read only (RO)d) Code or .text4. In 3c, what is other name for RO area, like ZI is called .bss.5. This is correct right?a) SRAM: .bss + .data + Stack + heapb) Flash: .text + RO
How much isolation between pins for stenciling? - Page 1
Forum section: electronics / beginners

author: alank2
author_rank: Super Contributor
timestamp: July 22, 2015, 02:50:28 pm
content: How much isolation between pins for stenciling? I've got 8 mil and 12mil that is giving me trouble with bridges though I have done 17mil successfully before. If you stencil, do you have a minimum isolation between pads that you use?Part of the problem might be that I am not very good at stenciling! When I pull up the stencil, some of the paste seems to smush down a bit and touched each other where there isn't a distinct separation...

author: Simon
author_rank: Unknown
timestamp: July 22, 2015, 03:22:49 pm
content: If there is not too much solder paste when you hot air it or oven it the paste will be drawn to the copper pads. For example it is common to drag paste across the pads for a soic or sop part and the solder just pull into the pad.

author: alank2
author_rank: Super Contributor
timestamp: July 22, 2015, 03:30:50 pm
content: So it is more of a problem of too much paste than the separation then. I ordered a 0.15mm thick stencil from, perhaps I should have tried the 0.1mm or 0.12mm instead.

author: peter.mitchell
author_rank: Super Contributor
timestamp: July 22, 2015, 03:32:02 pm
content: Spacing between stencil apertures doesn't matter so much, just make sure your stencil has the right aperture reduction so you have appropriate pad coverage (70-85%), and has the appropriate thickness for your pin density (ie, soic can be like 0.15mm thick stencil but 0.6mm bga needs 0.1mm thick stencil). If your stencil manufacturer does electropolishing, i recommend it, it makes the solder release much easier fro mthe stencil.

author: alank2
author_rank: Super Contributor
timestamp: July 22, 2015, 03:49:25 pm
content: I've been doing the default with is 100% coverage...

author: peter.mitchell
author_rank: Super Contributor
timestamp: July 23, 2015, 09:21:39 am
content: Quote from: alank2 on July 22, 2015, 03:49:25 pmwell theres your problem.

author: alank2
author_rank: Super Contributor
timestamp: July 23, 2015, 11:56:08 am
content: Quote from: peter.mitchell on July 23, 2015, 09:21:39 amI hope so. I changed my eagle settings to drc -> masks -> cream, min=0, 15%, max=10mil which reduced the cream layer pad size and ordered a new stencil from oshstencils. We'll see how this one does.

author: alank2
author_rank: Super Contributor
timestamp: July 24, 2015, 01:05:24 pm
content: Looking at the two different ipc standards, they both say: The information provided for the openings in the stencil is usually indicated as being the same size as the lands on the board for all components.Does this mean that 100% coverage should be used, but perhaps it is better to alter the size of the pads themselves for fine pitch parts to adjust their coverage?

author: chicken
author_rank: Frequent Contributor
timestamp: July 24, 2015, 02:05:36 pm
content: Fresh solder paste sometimes works wonders.
How much money to spend on a TDS220 - Page 1
Forum section: electronics / beginners

author: OSaG
author_rank: Newbie
timestamp: April 15, 2014, 09:37:19 pm
content: Hi to everyone at the eevblog forum!I am pretty new to electronics and have a question on buying a oscilloscope. I have picked up a very old 15MHz Telequipment D1015 scope, but it isn't fully working and i don't think i am able to fix itSo, i'm looking around on ebay for scopes an found a Tektronix TDS 220, but i don't have an idea how high i should place my bids. Is it worth spending money on this kind of scopes (DS1052 or TDS 200 Series) today for a beginner? Or shoud i save up for a 1000Z series scope?You must think i'm a 10 yo kid with that kind of bad english and questions, but - hopefully that changes soonGreets

author: kc9qvl
author_rank: Regular Contributor
timestamp: April 15, 2014, 10:09:52 pm
content: Well, I personally would not bid more than $100.00 US. You might want to go for the ds1052. More memory is always good. It is a current model comes with a warranty. If you are new to the electronics will you be able to repair the tds220 when it breaks. Not sure if holding out for a 4 channel scope would be be helpful. If you lose interest in electronics you would maybe break even on a tds220 on resale. You would lose money on new scope on resale.
How much power can a LC RF filter handle? - Page 1
Forum section: electronics / beginners

author: josefmtd
author_rank: Contributor
timestamp: October 14, 2019, 07:15:58 am
content: I am trying to design a LC low pass filter, but I am having doubts on how to know the maximum RF power that it can handle.I could not find any information in Google so I thought I might try asking here, reached out for some people on #electronics or #hamradio on Freenode but I'm still not sureI have a FM notch filter from Nooelec rated at 18dBm using what seems to be a 0603 inductors and capacitors, how does one calculate for the maximum rating of a LC filter? Is it based on the voltage the capacitors can handle? or mostly from the inductors?I hope someone can lead me to the right direction, since I'm quite lost since my previous design seem to fail delivering the full power from the transmitter

author: soldar
author_rank: Super Contributor
timestamp: October 14, 2019, 08:55:44 am
content: A woodchuck would chuck as much wood as a woodchuck could chuck if a woodchuck could chuck wood.https://www.w6pql.com/a_1.5kw_lpf_for_160-6m.htm
How much current can a usb 3.0 hub provide per port?  How is this typically managed? - Page 1
Forum section: electronics / beginners

author: salil
author_rank: Regular Contributor
timestamp: March 28, 2015, 06:01:03 am
content: And why do so many usb 3.0 hubs seem to only supply .5A per port despite coming with a 50-70w power supply? Many of these hubs claim to be able to handle 4-6A at 12v. USB power management is such a mystery...

author: Cliff Matthews
author_rank: Unknown
timestamp: March 28, 2015, 04:25:54 pm
content: Perhaps you can provide links to some products or the chips within?Do you want use the hub as an off-line multi-port charger? ..perhaps while the USB host is unavailable to enumerate a power budget?

author: Cliff Matthews
author_rank: Unknown
timestamp: March 29, 2015, 12:19:17 pm
content: Maybe this is what you're looking for:http://thewirecutter.com/reviews/best-usb-hubs/(The article is just a few weeks old, and gives a good look at current "state of the art" 3.0 hub-chargers).This one below is 45usd and offers 3.1 amps of charge across 2 ports plus 7 more with host connectivity... looks nice

author: salil
author_rank: Regular Contributor
timestamp: March 31, 2015, 07:22:48 am
content: Quote from: Cliff Matthews on March 28, 2015, 04:25:54 pmJust looking to use as a hub for many power hungry devices such as optical drives and bus powered external hard drives. No need for dedicated charging ports, I have plenty of Anker and apple usb wall chargers for that purpose.

author: salil
author_rank: Regular Contributor
timestamp: March 31, 2015, 07:24:01 am
content: Quote from: Cliff Matthews on March 29, 2015, 12:19:17 pmYes, I've seen that hub but it's unclear how much current each port can provide in the hub (not the charge only ports)
How much should i charge? What parameters to consider - Page 1
Forum section: electronics / beginners

author: ppTRN
author_rank: Regular Contributor
timestamp: July 19, 2023, 03:08:59 pm
content: So, I am a relatively young EE (26, Italy) and I already work as a teacher in an high school. Several times I was requested to design and develop some circuits, mainly digital based on ESP32, nothing particularly difficult. For the first job I did the full design and prototiping, even designing a pretty 3d enclosure. It worked fine. I charged the guys for a ridicolusly small amount of money, but I was happy just because I proved to myself I was capable of doing it.Jobs like this kept coming, and I am finding myself in a very akward position: I do not know how much my job is worth.For small repair stuff I charge partially on the working time (something like 20€/h) plus a fee that takes into account the actual trubbleshooting and the importance of the item i am fixing.But for designing and prototiping? Full developement of a custom board based only on the customer needs, prototiping, testing and delivery of a couple sample + all the files for ordering pcb online?What guidelines do you guys follow?Also, for next project, i am seriously considering delegating small pieces of circuit to be designed by other EEs, and I just put everything together. How much should THEM be payed?Hope this is the right forum section for my question.Modify message

author: eugene
author_rank: Frequent Contributor
timestamp: July 19, 2023, 07:01:27 pm
content: Typical engineering consulting fees in the US tend to run between $45/hour and $150/hour depending on both the engineer and the client.
How much thicker is a square header pin than 22AWG solid wire? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: January 07, 2014, 02:07:02 pm
content: From what I can find square .1inch header pins like the ones use in IDE connectors are usually .635mm thick.22AWG seems to often be referred to as .6mm. Does this sound right?Each face of a square header pin is .035mm thicker than diameter of the round cross section of 22AWG solid wire?Diagonally a square pin is even thicker at .898mmif my a2+ b2= c2calculation is correctOops. I just checked Wikipedia and found the table where 22AWG seems to be 0.644mm so I guess it's so close to the size of a square pin (when it's not turned 45 degrees) it might as well be the same.I might see if I can find a way to flatten the corners of square pins to make it more octagonal.

author: Unknown
author_rank: Unknown
timestamp: January 07, 2014, 05:24:47 pm
content: What you want to be comparing is the CSA (conductor surface area).22AWG has a CSA of around .35mm².A .635mm square pin has a CSA of around .4mm²Although after rereading your OP I'm not sure what your question is?

author: dentaku
author_rank: Frequent Contributor
timestamp: January 08, 2014, 10:20:57 pm
content: I'm just wondering about the thickness because I know that using anything thicker than 22AWG wire in a breadboard eventually loosens up the clips.It has nothing to do with conductivity or anything seriousQuote from: Lurch on January 07, 2014, 05:24:47 pm
how much voltage can old 6P14P tubes take? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: February 06, 2020, 02:00:56 am
content: I know that they are claimed to only hold 250volts anode voltage. but I've seen more than that in a LOT of amps.usually about 265vso I wanted to have 360v on the plate but I am sure it will arc over in the tube.so what would be the max voltage it can take really and what will be the consequences of using such high voltage?also, I know that new 6P14P tubes can usually hold a lot more voltage since they're better quality.so what can a new 6P14P tube hold?also, 6P1P tubes are basically 6P14P 2.0 so can they hold more voltage? they are claimed to only hold 250v same as the 6P14P's but they are better in most other ways so it might be just underrated?oh and 6P14P tubes are a Russian copy of EL84's with a 6V heater, and the 6P1P's are Russian copies of EL90 tubes.

author: amyk
author_rank: Super Contributor
timestamp: February 06, 2020, 02:16:55 am
content: According tohttps://www.hobbielektronika.hu/forum/getfile.php?id=21127, absolute max of 300-400V, but it's hard to give a concrete answer because you're essentially asking "what's the distribution of maximum anode voltages and the manufacturing process variation".

author: gbaddeley
author_rank: Regular Contributor
timestamp: February 08, 2020, 08:14:50 am
content: Not sure why you would want 360V on the plate, as that is outside it’s normal operating range. Performance will be pitiful in a number of aspects.

author: Kirill V.
author_rank: Regular Contributor
timestamp: February 08, 2020, 07:16:47 pm
content: Quote from: ELS122 on February 06, 2020, 02:00:56 amExcess voltage drop on the anode load, probably.An important parameter is the power dissipated at the anode. An increased anode voltage is dangerous by a breakdown between the electrodes. Since this pentode is intended for output stages of household audio equipment, I would not count on the ability to tolerate high voltages.
How Reflections are generated in unmatched transmission line? - Page 1
Forum section: electronics / beginners

author: Kedar264
author_rank: Regular Contributor
timestamp: May 24, 2015, 05:28:18 am
content: I perticularly want to know about joints in tratransmission line ,how sigals reflection occure at joints . Thinking a lot ...Please let me know Any related contents .

author: miguelvp
author_rank: Super Contributor
timestamp: May 24, 2015, 06:23:06 am
content: These two videos might help:

author: hamster_nz
author_rank: Super Contributor
timestamp: May 24, 2015, 06:42:18 am
content: Watch and understand...Oldie but a goodie

author: AlfBaz
author_rank: Super Contributor
timestamp: May 24, 2015, 06:47:23 am
content: you can also have a look at this previous threadhttps://www.eevblog.com/forum/chat/how-are-signals-reflected-in-a-wire/

author: John_ITIC
author_rank: Frequent Contributor
timestamp: May 24, 2015, 06:53:45 am
content: Quote from: Kedar264 on May 24, 2015, 05:28:18 amI would suggest studying the first 5 hits on Google.https://www.google.com/search?q=pcb+transmission+line&ie=utf-8&oe=utf-8#q=transmission+line+reflections

author: Rupunzell
author_rank: Frequent Contributor
timestamp: May 24, 2015, 07:40:51 am
content: Adding a bit of math and theory.Spend the time to watch lecture series 5, then lecture series 6. This will give some foundational knowledge to how this transmission line stuff works.Bernice

author: miguelvp
author_rank: Super Contributor
timestamp: May 24, 2015, 08:21:56 am
content: Quote from: hamster_nz on May 24, 2015, 06:42:18 amI love those wave machines.

author: Jeff1946
author_rank: Regular Contributor
timestamp: May 24, 2015, 08:02:32 pm
content: You may want to check out this web site on vibrations,http://www.acs.psu.edu/drussell/Demos/reflect/reflect.htmlto compare a wave on a string to a transmission line. Note how the wave is inverted with a hard reflection (transmission line shorted) vs a soft reflection (transmission line open). With perfect termination, typically 50 ohms, there is no reflection as if the transmission line went out to infinity.
How safe is an electrolytic capacitor after reverse polarity ? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: October 21, 2023, 06:06:43 am
content: I just had a new 10uF 50V JRB -40-105C cap put in backwards on a 5V rail, for about 2-5 minutes. It's not even warm, but I've blown up 2-3 caps with reverse polarity over the past few years. I didn't take long either, on a 12V rail and a -12V rail.So how healthy might it still be ? It's only been used on a breadboard a few times.

author: Vovk_Z
author_rank: Super Contributor
timestamp: October 21, 2023, 07:12:45 am
content: Put it under positive voltage (>=1/2 rated) for several minutes or longer and measure a leakage current. If leakage current is very small (<1 uA) then possibly it is fine.

author: amyk
author_rank: Super Contributor
timestamp: October 21, 2023, 08:33:29 am
content: If they weren't totally destroyed by the reverse bias, putting them back in the right way and keeping voltage on them (while monitoring the current) should see them reform their dielectric again.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 21, 2023, 12:53:09 pm
content: 5V is enough that there was probably some internal reaction. But evidently not much if they didn't get warm from it.Usually, reversal of a few volts is acceptable, or some percentage depending on rating. Chemically, the cathode foil has some natural oxide, not nearly so well crafted as the anode, but enough to hold off a couple volts; also give or take the ionic double layer effect.At worst, some reforming will be fine.Tim

author: MathWizard
author_rank: Super Contributor
timestamp: October 21, 2023, 01:08:44 pm
content: Ok I'll try it again with a series resistor, and leave it for a while, see if it's capacitance changes or if it leaks.My main worry is it blows up on the breadboard and hits me in the eye, but I'll try it anyways. Thanks

author: macboy
author_rank: Super Contributor
timestamp: October 21, 2023, 01:10:15 pm
content: A 10 uF 50 V cap costs what, 10 cents? To be practical about it, junk it and take another out of the parts box.If you really need to know if it's good, compare capacitance, ESR, and leakage current to a known good one.

author: RayRay
author_rank: Frequent Contributor
timestamp: October 21, 2023, 05:36:38 pm
content: Quote from: MathWizard on October 21, 2023, 01:08:44 pmI'd suggest you get yourself a good pair of safety glasses! As well as not stand too closely to a breadboard/circuit board when you suspect things could go badly. But I overall agree with the advice given by macboy. A capacitor is a cheap component that is easy to replace, why insist on continuing to use it and take unnecessary risks?