hybridfree/eevblog-posts huggingface dataset:
how do i differentiate a teflon cap from a wet or axial tantalum? - Page 1
Forum section: electronics / projects

author: jaunty
author_rank: Regular Contributor
timestamp: July 18, 2016, 07:24:12 am
content: I've been buying leftover lots of teflon caps on ebay for what seem like great prices for a while... and now I'm looking at using some of these in some circuits - it occurred to me that some of them might not be teflon caps but actually axial / wet tantalums but I'm really unsure about how to differentiate between them. Any suggestions? thanks

author: singapol
author_rank: Frequent Contributor
timestamp: July 18, 2016, 09:00:31 am
content: simple...cut them open and compare but do be careful of the wet type they can be toxic so handle with care.Teflon is just film and foil or at least metalised.Teflon is heat resistant so can subject to flame test.Hope this helps.Edit: heat test when compared to mylar/polyester film.

author: Pjotr
author_rank: Frequent Contributor
timestamp: July 18, 2016, 09:19:32 am
content: Hi-Rel Mil-spec Ta and PTFE caps can have the same hermetically sealed RVS/Nickel casing indeed. Simply measure them: PTFE caps have low values: app: < 1 nF while Ta have high values app > 1uF. Also leakage current of PTFE is very low, unmeasurable without special set up. While leakage current of Ta's is relatively high: > uA.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: July 20, 2016, 07:50:17 pm
content: Put them on a bridge and measure dissipation factor. Teflon will be near zero, near impossible to measure on most equipment. Tantalum will be much higher. A simple bridge is really easy to build if it only has to cover a limited range of values.

author: David Hess
author_rank: Super Contributor
timestamp: July 21, 2016, 02:42:08 am
content: Physical size versus the capacitance-voltage product will reveal the difference between a film and electrolytic capacitor; teflon capacitors are really large and larger than even other film capacitors. Measuring dissipation is much more definitive. Dielectric absorption will reveal the difference between teflon and other film capacitors.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 21, 2016, 03:31:56 pm
content: If you don't have a loss bridge, the ESR of the larger (tantalum) caps will be apparent by driving one with a 50 ohm signal generator at modest frequency (100kHz+?) and measuring the voltage drop. The similarity of the waveform represents loss versus capacitance; for parts of some uF, the capacitive reactance should be negligible at this frequency, hence a square wave will hardly be tilted at all.Between the smaller values, and the lower losses, the teflon caps should show as rounding the square wave corners off, with no impact on overall amplitude (if the value is small enough for the switching frequency, anyway).Tim
How do I fix this and do a better job at probing it? - Page 1
Forum section: electronics / projects

author: itstemo1
author_rank: Newbie
timestamp: January 01, 2013, 10:49:29 pm
content: This is the header for the Zune

author: robrenz
author_rank: Super Contributor
timestamp: January 01, 2013, 11:06:45 pm
content: Use solder wick to get rid of the solder bridging.Tin your probe wire and clean and re flux it. flux the test point you want to solder to.Then use a clean iron tip to just melt the tinned lead to your test point.
How do I go about finding out why this Lm3886 amplifier won't work ? - Page 1
Forum section: electronics / projects

author: Hextejas
author_rank: Frequent Contributor
timestamp: November 02, 2018, 10:07:07 am
content: Or for that matter, how do you go about debugging a board ?I built this thing I thought correctly. I am getting various readings at the different pins on the lm3886 but I don't know what to compare them to. I have it attached to a cheap speaker and am inputting a 1khz test tone. No joy.

author: Zero999
author_rank: Super Contributor
timestamp: November 02, 2018, 11:30:28 am
content: A schematic and photograph of the layout would help.It could be a power supply or physical construction issue. Have you tried replacing the speaker with a dummy load resistor and looking at the waveform using an oscilloscope?

author: macboy
author_rank: Super Contributor
timestamp: November 02, 2018, 03:57:36 pm
content: Did you connect the Mute pin correctly, to disable the (default) muting of the output?

author: Hogwild
author_rank: Regular Contributor
timestamp: November 03, 2018, 06:06:42 pm
content: I agree-photos and an oscilloscope reading are suggested, esp for beginners. I built the guts of two stereo LM3886 amps and found it very hard, at least initially, to troubleshoot without a scope (even though I'm a total newbie). If you don't have one, see if an electronics repair shop near you might, or maybe you know someone else...

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 04, 2018, 01:34:39 am
content: Quote from: macboy on November 02, 2018, 03:57:36 pmIf everything seems correctly hooked up and power supplies are OK, I would indeed look no further than the Mute signal.

author: Hextejas
author_rank: Frequent Contributor
timestamp: November 04, 2018, 02:35:55 am
content: Well, I have tried a lot of different stuff to no avail. So tomorrow I will begin removing the parts and stuffing them into a new board.I really thank you for all the help.
How do i know if my RJ45 connector is capable of POE++ - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: November 30, 2020, 03:58:32 pm
content: Im looking for a pcb mount RJ45 connector that capable of POE++ (PD 50W). Unfortunatly the datasheet does not say anything about the electrical characteristics ofthisspecific connector, i liked it since it relativly cheap and most importantly it has LED and no metal tabs.

author: coromonadalix
author_rank: Super Contributor
timestamp: November 30, 2020, 06:08:09 pm
content: normally if its an simple rj45 plug with no signal transformer in it, the supply line will come from the main router / hub and should match this specificationhttps://satoms.com/power-over-ethernet-poe-explained-and-specifications/

author: coromonadalix
author_rank: Super Contributor
timestamp: November 30, 2020, 06:11:24 pm
content: connector datasheet it seems okayhttp://www.farnell.com/datasheets/1840742.pdf

author: drakejest
author_rank: Regular Contributor
timestamp: November 30, 2020, 06:34:38 pm
content: Oh cool you found the datasheet, A rated current of 1A seems good, should be around the 60W rating
how do I know when a wifi module is transmitting or receiving? - Page 1
Forum section: electronics / projects

author: nomar123
author_rank: Contributor
timestamp: March 17, 2022, 12:58:58 pm
content: I have a development board with a WL1837MOD module on it for wifi. I have a set up with another device that sends a video image over wifi to the dev board. The wifi module has 4 data lines that can be inputs or outputs, obviously because both devices are sending data back and forth, so each device will either have a data input or a data output.This may be my lack of wifi knowledge, but if I were to probe the data lines, how do I know if the data I am seeing is a transmit or a receive? I looked thru the WL1837MOD datasheet to see if there was a timing diagram or something that shows another pin changing state if it is transmitting or receiving, but no luck. Would I need to find a wifi spec and become more familiar with the protocol to better understand this? Could someone point me to some resources that might help?update: found the attached diagram which is what I think i am looking for. I am still not sure how to properly probe this to be sure that I know if I am looking at a transmit or receive...any help understanding would be greatly appreciated

author: thm_w
author_rank: Super Contributor
timestamp: March 17, 2022, 10:26:12 pm
content: You'd want to use a logic analyzer to decode what commands are being sent/received:https://prodigytechno.com/sdio-protocol/Sigrok and others should be able to do it.

author: SL4P
author_rank: Super Contributor
timestamp: March 17, 2022, 11:49:26 pm
content: You might be able to put a tiny antenna near the wifi antenna, and check for any radiated powerShoukd be pretty simple.

author: Renate
author_rank: Super Contributor
timestamp: March 18, 2022, 06:44:06 pm
content: You have to clarify what you want, i.e. direction of data transfer over SDIO or whether it's actually RF transmitting.I'd put a high side current monitor (INA-219, INA226) on the module. Transmitting is easy to differentiate, it takes 100 times more power than receiving.
How do I power this? (small 300v PSU) - Page 1
Forum section: electronics / projects

author: Murphy
author_rank: Regular Contributor
timestamp: December 05, 2010, 05:38:02 pm
content: I've had this thing around for a while and I'm trying to figure out how to power it up. I traced the circuit to try to figure out what to hook up to the header but it looks a little weird and my analog skills aren't too good yet. Seems standard enough maybe somebody more experienced could point me in the right direction.Looks like the output is regulated and it needs a split supply somewhere around 15v but I'm not sure how to hook up the power between pins 1-4, or what to do with pin5 which looks like it might be an output voltage adjustment.

author: saturation
author_rank: Super Contributor
timestamp: December 05, 2010, 11:20:40 pm
content: HiWhat seems like an oscillator section using the LM308? on the left of the schematic is a bit hard to follow, but the segment with the set of 2 diodes in series on the upper right, with the BRN input, appears as a half-wave series multiplier described here:http://en.wikipedia.org/wiki/Voltage_multiplierThe input BRN should be fed by the BRN output of the step up 2.3:1 transformer.It may be good to begin with the data sheet of the LM308? [ if its truly this] and insure the pins you trace are connected thus.http://www.national.com/opf/LM/LM308.html#DocumentsSamples of types of oscillators using an op amp are described here:http://www.allaboutcircuits.com/worksheets/opamp10.htmlIf you do get it fired up, be very careful, 300V is lethal voltage, and the size of these caps can provide enough current to cause cardiac issues.

author: Murphy
author_rank: Regular Contributor
timestamp: December 06, 2010, 04:28:47 am
content: Yeah sorry about the crude schematic, was the best I could do all in one go. If this proves difficult I might clean it up some.The top right is definitely a (badly drawn) multiplier, and I'm well aware how much a charged cap can hurt.The op-amp pins I labeled did come from the datasheet but could probably do with some double checking. Thanks for the link, I was thinking the 2 transistors would oscillate on their own and the opamp simply regulated the output but it does look similar to one of those arrangements. I'll read through that page and compare it to what I have.The diodes look like they're all 1N4148F (some sans F) 100v switching diodes.The circuit just looks weird to me I'm going to have to check for errors tomorrow.
How Do I Read A 'Drift Nomogram' - Page 1
Forum section: electronics / projects

author: Maximus
author_rank: Contributor
timestamp: April 16, 2015, 04:26:56 am
content: I have seen this type of graph in several resistor datasheets and have no idea how to read it or what it is trying to tell me. I figured this wasn't quite a beginner question so I posted it here.Datasheet here:http://www.vishay.com/docs/28729/pr010203.pdfpage 9

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 16, 2015, 04:39:39 am
content: It's a very clever way to figure out the drift of the resistance value given the power dissipation, ambient temperature, nominal resistor value, and operating time. Follow the dotted line.It's telling you that at 0.5W dissipation, at 70C ambient, a resistor near 30K, after 10000 hours, will have drifted something like 0.8% from its value.Try it with different conditions, drawing different lines.Or I could be dead wrong.

author: Maximus
author_rank: Contributor
timestamp: April 16, 2015, 04:44:48 am
content: Fantastic, its one of those 'obvious once some one points it out' kinda things. Thanks for your help.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: April 16, 2015, 02:21:41 pm
content: You're welcome. Are you designing something with long term stability in mind?

author: Maximus
author_rank: Contributor
timestamp: May 03, 2015, 08:17:27 pm
content: oops, havent checked back in for a while. No nothing that needs long term stability, just curiosity.
How do I update a valence V7001 GPS for 2019 rollover ? - Page 1
Forum section: electronics / projects

author: daslolo
author_rank: Regular Contributor
timestamp: April 04, 2020, 10:12:32 am
content: This venerable Nexstar 11 GPS has a Valence VS7001 which doesn't do the 2019 rollover so I'd like to update the chipset firmware to bring it up to date.Has anyone done that?
How do I use a TPM chip to secure access to data? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: February 24, 2023, 02:39:31 pm
content: With reference to (for example) Infineon's SLB 9670XQ1.2After reading a fair bit around the subject I'm still unclear what the process is for implementing controlled access to some resource such as a data record or hardware device.Suppose I have some data to protect. I need to read the data often, but only rarely update it. For example the data might be setup data.Somewhere in the system is a standard micro-processor that wants to read the data. Somehow, I do not understand how, only this micro-processor can successfully do this.I do not know whether the data itself is meant to be stored outside the TPM chip (presumably in encrypted form), and how the key inside the chip is used to grant access (to that data) to another 'entity'.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: February 24, 2023, 03:13:05 pm
content: The TPM serves one primary purpose: to house and hide the encryption keys, so you don’t have to leave them out unprotected elsewhere, like in a flash memory.Whenever you need encrypt/decrypt/hash/sign/key derivation ask the TPM to do it for you.If you want more details:https://library.oapen.org/bitstream/handle/20.500.12657/28157/1001837.pdf?sequence=1&isAllowed=y
How do I use TL494 output: Common emitter or common collector? - Page 1
Forum section: electronics / projects

author: hkBattousai
author_rank: Regular Contributor
timestamp: July 09, 2014, 02:22:38 am
content: I studied TL494 datasheet carefully, but still I can't make sure of one thing (because it is not clearly stated). With what output configuration do I obtain two PWM signal with dead-time between them? Please refer to the schematics below.Since these two configurations will give out mutually inverse pulse waveforms, one of them will yield proper dead-time while the other one will cause shoot-though. I feel that the correct configuration for my case is the common collector (emitter follower) one, but I need an experienced users confirm to get rid of my worries.Note: The blocks represented as "Mosfet Driver" turn on their both high and low MOSFETs when their input are high, and vice versa.Links:TL494/TL594 DatasheetDesigning Switching Voltage Regulators With the TL494A Simplified Power Supply Design Using the TL494 Control Circuit

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 09, 2014, 12:06:39 pm
content: The emitter side output example provides active-high pulses.Use example:http://seventransistorlabs.com/tmoranwms/Circuits_2010/12-24_Converter.pngTim

author: hkBattousai
author_rank: Regular Contributor
timestamp: July 09, 2014, 12:10:56 pm
content: I have found another example circuithere.This one also takes the driving pulses from the emitters.

author: GK
author_rank: Super Contributor
timestamp: July 09, 2014, 12:17:15 pm
content: The NPN emitter follower outputs of the TL494 can actually sink current as well as source it, even so they are not supposed to be used that way. I found this out by accident when I once hastily bread boarded a buck SMPS with a TL494 after only skim reading the datasheet. I drove the gate of the moderately beefy N-ch MOSFET directly from the emitter follower outputs (paralleled). Switching frequency was 60kHz and it worked fine.There is a TI applications note on the use of the TL494 which details the internal schematic. If you study the schematic for the emitter follower outputs it is clear how the follower outputs can both sink and source current. However I would not bet on it for long term reliability!
How do I wire a relay normally closed ald118 - Page 1
Forum section: electronics / projects

author: psxpetey1
author_rank: Regular Contributor
timestamp: February 01, 2021, 05:06:15 am
content: Messing around with a psu and I want to have a relay wired permanently closed. A device I have turns off the relay if it detects that it doesn’t get enough power and it’s very sensitive. I’m curious if this will cause the device to boot.The data sheet for the ald 118 is here:https://www.digchip.com/datasheets/download_datasheet.php?id=4661871&part-number=ALD118I assume I wire the NO pin to one of the coil pins but which one?I first tried wiring the com pin to the no pin but that didn’t work out.So am I correct in assuming I wire no to the coil and if so which pin lol

author: deskpro256
author_rank: Contributor
timestamp: February 01, 2021, 06:24:11 am
content: Hi, the NO means normally open, which is the replay output pins. The coil pins are what you connect to your control circuitry.It seems that this relay only has 4 pins, 2 for the coil and 2 outputs: COMMON & NORMALLY OPEN.COM and NO are not connected until you energize the coil pins. Also, are you using 18V to energize the coil, because according to the datasheet, your specified relay coil needs 18V to energize it.So you would need to have the coil energized all the time and turn it off when your power thing becomes too low.Maybe you should use a relay the has the NC (normally closed) so you don't have to have the coil energized all the time, might save you power.Or you should use a 5V relay. Depends on what voltage your control circuit uses. There was also ALD105W and others.Does this help you in any way?EDIT:Added a more appropriate connection diagram.

author: psxpetey1
author_rank: Regular Contributor
timestamp: February 03, 2021, 06:38:11 am
content: Quote from: deskpro256 on February 01, 2021, 06:24:11 amSort of. This is a component in a power supply so I won’t be using different relaysWhen the device is in standby of course it is open. When the device has the power button pressed this relay clicks and I assume allows power to flow to the output pins. So I want to wire it always closed to see if the device will stay on.But you are saying I need to supply it with 18v to close it so I can’t just wire it closed because the voltage isn’t there anyway to have the device turn on. 🤔 maybe there is another chip that supplies this one to make it click on when power is pressed

author: deskpro256
author_rank: Contributor
timestamp: February 03, 2021, 08:31:43 am
content: Ok, its in circuit.If you now know which pins are the coil pins, you can try to trace them to what turns on the relay, could be a transistor controlled by some microcontroller. Might be as easy as pulling the transistor base low or high with a resistor, depending on what is actually there. If you have images of the PCB itself or some more info you could post it here.Might be worth a shot.
How do my USB traces look? - Page 1
Forum section: electronics / projects

author: vini_i
author_rank: Regular Contributor
timestamp: December 22, 2017, 02:57:56 am
content: This is my first try at laying out USB 2.0 high-speed traces. I'm using a 2 layer board.It took me forever to get all the info together. Zdiff = 2 * Zodd and Zsingle = Zeven / 2With my calculations, I should get 92 ohm diff impedance and 75 ohm single ended impedance.This is using a 26 mil trace and 6 mil space. The traces are just shy of 12mm long.The difference between the two traces is 0.03mm.From all the app notes I read, it is acceptable if the traces change size but only very close to the ends.How does my layout look?

author: marshallh
author_rank: Unknown
timestamp: December 22, 2017, 03:21:16 am
content: Looks about right. On 2layer the microstrip will be so far from its reference plan (you must put ground under it, obviously) that the traces will be thick. It's even worse for 50ohm, you can see those traces from space.Don't worry about it too much, USB2 could work over wirewrap. I've seen USB3 hubs on 2layer with slots cut all over the reference paths and it still worked....

author: ataradov
author_rank: Super Contributor
timestamp: December 22, 2017, 04:31:17 am
content: Don't worry about it too much. Look at any development kit with USB - they all just use standard trace with and it works fine. And for such short distances, it matters even less.

author: vini_i
author_rank: Regular Contributor
timestamp: December 23, 2017, 01:10:24 pm
content: Thanks guys, I'll let you know how it works after I have it made.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 24, 2017, 12:20:28 pm
content: Quote from: blueskull on December 22, 2017, 03:33:27 amThis. Also, it looks like you can shove the chip about 6mm over, making it even less important.Tim
How do output on/off switches on power supplies usually work? - Page 1
Forum section: electronics / projects

author: Matir
author_rank: Contributor
timestamp: May 23, 2017, 12:57:15 am
content: I feel like this is a stupid question. Many power supplies have an output on/off switch -- allowing you to set the voltage and current limit before actually outputting anything. How would these typically work? I can imagine 3 scenarios:1) The output linear regulator is brought down to 0V. (Assuming a regulator that can go all the way to 0V)2) A MOSFET on the output, but this seems like it would introduce a voltage drop.3) A relay on the output, which will have the lowest voltage drop and work in all cases.I'm thinking of building something similar to Dave's uSupply or something as a small 12V/1A bench supply.

author: BrianHG
author_rank: Super Contributor
timestamp: May 23, 2017, 01:09:20 am
content: The nice thing about a 2 pole relay is that you can completely disconnect from the supply's +&-. No worry about surge in any direction until the mains switch is engaged and the output is stable. With a mosfet switch, you can blow the mosfet if there is a large voltage on the output before you switch on your supply. As for the regulator working down to 0v, you just need to make sure you don't drive your output transistor with any type of pulse during power-up.

author: timb
author_rank: Super Contributor
timestamp: May 23, 2017, 01:30:32 am
content: Quote from: Matir on May 23, 2017, 12:57:15 amTypically they use a relay. I've also seen some of the larger power supplies (10A+) use a soft start in combination with the relay (that is to say, when in "off" mode the current limit is internally set to 0; when you switch the supply on the relay is engaged and then the current limit ramps up to your set point over a short length of time (us to ms)). They do this so the relay contacts don't have to switch a large voltage or current, which can cause arcing and wear them down.
How do powered, no neutral, wall lamp switches work? - Page 1
Forum section: electronics / projects

author: VaSe7u
author_rank: Newbie
timestamp: June 23, 2018, 09:14:35 pm
content: There are wall lamp switches with electronics for touch buttons and remote control that are connected in series with the lamp, like this onehttps://www.livoloeurope.eu/livolo-wifi-touch-light-switch-with-glass-panel-vl-c701-11.The only explanation about their operation I found was that they use two power supplies. When the lamp is on, a step-up transformer is used, because the voltage drop on the switch is low and the current is relatively high. And when the lamp is supposed to be off - it is dimmed to complete the circuit.I'm curious about a more detailed explanation.

author: CopperCone
author_rank: Super Contributor
timestamp: June 23, 2018, 10:37:08 pm
content: the marketing with the figure skater is lol"or something hard" i wonder what that would bei also wonder why you would attack it with a knife or 'something hard'incase the figure skater try to get away from you and you miss?did they have convicts do the marketing on this shit? the violent predator has clearly been rehabilitated with prison acquired knowledge of electrical engineeringseriously, is the scream killer or jason vorheves marketing this?you got kissing in the first picture (im not giving any points here for the woman looking to be in charge of that maneuver since we are politically correct (fatal attraction), then a figure skater raising her leg up, then talk about knives and hard things, then scary PCB soldered brass mains contactshey, then when you scroll down you can even see what kind of looks like jasons hokey mask as the back cover of the PCBi think the design time had something on their mind loli dunno, if you buy from that company maybe consider getting some home security upgrades

author: MasterT
author_rank: Frequent Contributor
timestamp: June 23, 2018, 11:20:01 pm
content: The difference between this classic regulator and more advanced /modern one is only in IC sensor chip implementation. But the way it's getting power is the same, it's cut some voltage, few degree or so, before the thyristor fires up and closed circuitry. Modern IC doesn't need much power to operate, and thyristor itself needs only short pulse of current, so there is newer 100% power at the load, but very close to it, probably 98-99%. I'm lazy to search a formula, though do yourself your homework

author: tsman
author_rank: Frequent Contributor
timestamp: June 24, 2018, 01:39:18 am
content: The no neutral required smart switches work by passing a very low current through the bulb to complete the circuit and power itself. This trick is from the incandescent bulb days as such a low current won't be enough to cause it to emit any light. This is why your switch mentions you may need a"Lighting Adapter"if your bulb is lower than 15W as that low current may be sufficient to charge the capacitors in the LED bulb and cause flickering. They mention this on the adapter page. Another problem is that the LED may illuminate very dimly.
How do pulse rated chip resistors differ from regular resistors? - Page 1
Forum section: electronics / projects

author: incf
author_rank: Frequent Contributor
timestamp: May 13, 2025, 12:18:00 am
content: How do pulse rated chip resistors differ from regular resistors?What is the "special sauce" that make them pulse worthy?Different materials used in construction?*Lack of laser trimming? (or better/more expensive laser trimming?)Looser specifications? (could it just be a game of specmanship and increased prices?)Something else?What happens if you torture a commodity resistor with very short but large transient pulses? (eg. lightening strike, etc.) Might they fail in an interesting way? Or maybe they might do nothing more than drift a little in value? etc. etc.As far as I can tell, there is quite a bit of variability between manufacturers. For example the story Stackpole tells seems fairly straightforward. Other manufacturers rate their resistors differently despite being apparently the same thing.*I saw some Asian datasheets talk about Rubidium Oxide

author: jwet
author_rank: Frequent Contributor
timestamp: May 13, 2025, 05:41:06 am
content: They're actually made different and its more expensive. Its not just marketing. Lightening is kind of off the table but surge is doable.The formula for resistance is R= rho * L/A. The Rho is material dependent and there are a bunch of thin and thick film materials. Some can take peak currents and dissipate transient thermal better. They can make a device with the same resistance with the same L/A but scale L and A. The A sets the current density (J- amps/meter^2). They also have finger designs and other tricks to improve pulse handling.They do cost a bit more and you'll see parallel/series arrays to get something like their performance.I don't know what magnitude of current pulses you're looking at but 200 amp pulses create some real mechanical force on small components.Have fun.
How do you breadboard DPAKs? - Page 1
Forum section: electronics / projects

author: iXod
author_rank: Frequent Contributor
timestamp: October 29, 2020, 05:06:07 pm
content: Bought DPAK MOSFETS that meet my design requirements and expected to be able to breadboard them with those little DIP adapter pcbs. I have lots of adapters for SOIC and SOT but I find exactly 1 seller of DPAK adapters on e-Bay for exorbitant prices.Is there a simple way to breadboard DPAKs?Thanks.

author: wraper
author_rank: Unknown
timestamp: October 29, 2020, 05:12:18 pm
content: Just solder leads on top of existing terminals. It's not like it's some tiny part where this is problematic to do. If it needs heatsink, solder a flat piece of copper on it's tab.

author: FenTiger
author_rank: Regular Contributor
timestamp: October 29, 2020, 05:12:28 pm
content: I've soldered DPAKs to Veroboard before. You could easily make yourself a breadboard adapter like this.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 29, 2020, 05:52:24 pm
content: - Get the IPAK version.- Breakout board.- Don't, carve up some copper clad.Tim

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 29, 2020, 05:58:37 pm
content: solder teh 2 leads directly to a pin-header, and a wire to the tab to a third pin
How do you call this component? - Page 1
Forum section: electronics / projects

author: Alexandros81
author_rank: Regular Contributor
timestamp: March 12, 2018, 11:45:59 am
content: Hi!I wish to know how do you call the component next to the pin header (to the left)?I was doing a search in farnell to find the name of it (with no success) in order to find it in Eagle.ThanksAlexandros

author: Cloud
author_rank: Regular Contributor
timestamp: March 12, 2018, 12:00:10 pm
content: You mean this?http://si.farnell.com/w/c/connectors/board-to-board-connectors/prl/results?range=exc-direct-ship|inc-in-stock&st=socket+2.54mm

author: Nusa
author_rank: Super Contributor
timestamp: March 12, 2018, 12:11:20 pm
content: I don't know what Eagle calls them, but I call it a female pin header.I keep 40-pin strips of both types handy for prototyping. The male ones are breakaway, the female ones can be cut to length with a loss of one pin.

author: chrisl
author_rank: Regular Contributor
timestamp: March 12, 2018, 12:12:42 pm
content: https://www.digikey.com/products/en/connectors-interconnects/rectangular-connectors-headers-receptacles-female-sockets/315?k=headerFemale header, sockets... etc.
solved: how to do stability analysis of a TL431 regulating the output of LM317? - Page 1
Forum section: electronics / projects

author: incf
author_rank: Frequent Contributor
timestamp: June 18, 2025, 05:34:36 pm
content: As the title says: "How do you do a stability analysis of a TL431 regulating the output of a LM317?"Where should you cut the loop? (I feel like there are multiple places where it could be cut)How do you adjust the phase margin?With something like an op-amp it is fairly straightforward. But this is my first time with multiple feedback loops.Attached is a simulation where I attempted to do so. As far as I can tell, the magnitude is somewhat correct. Not sure about the phase. The output only varies at high frequency due to the action of the TL431.*the ancient 317 spice model I found will oscillate without an output capacitor.

author: MariuszD
author_rank: Regular Contributor
timestamp: June 19, 2025, 11:26:57 am
content: Quote from: incf on June 18, 2025, 05:34:36 pmOn the schematic, I see something different. TL431 regulates the input of LM317.These two ICs have independent feedback loops. You can test pulse response. But you can't inject AC to both loops at the same time.You might be interested in this circuit, it does what you describedhttps://www.diyaudio.com/community/threads/lm317-tl431-really.248335/

author: incf
author_rank: Frequent Contributor
timestamp: June 19, 2025, 01:04:56 pm
content: That is a good observation.The TL431 does not need to be connected to the 317's output.

author: xavier60
author_rank: Super Contributor
timestamp: June 19, 2025, 01:46:05 pm
content: For the TL431 to contribute to regulation accuracy, it needs to sense output voltage.A capacitor should go between K and R of the TL431 so only the LM317 provides fast response to load transients.A resistor between OUT and ADJ of the LM317 should provide minimum load for both ICs.
How do you find applicable standards? - Page 1
Forum section: electronics / projects

author: fredboivin
author_rank: Regular Contributor
timestamp: March 05, 2015, 01:53:51 pm
content: Hi,I am in the process of selecting an AC DC converter module that will go inside a UL864 listed product and got overwhelmed when searching for the applicable standards the module should meet. When I asked my surroundings, the response was foggy at best...Except learning them all by heart, what is your method to find applicable standards for your projects? Is there a dedicated standard savvy person in your group, do you contact the agencies, do you take inspiration from similar products, do you know a good tool or a resource, etc?Anyway. About my power supply, I found that if it meets UL60950, there is only a couple more tests I have to perform to qualify it for UL864. Does that sound right?Thanks!

author: Neilm
author_rank: Super Contributor
timestamp: March 05, 2015, 05:32:41 pm
content: In the UK things I design have to be CE marked for sale in Europe. Due to that, I would look at gov and EU websites which would state what EU directives it needs to meet. (I might also look at competitors to see if they state what they meet). From them, I would then check to see what standard would be required to presume conformance with the standard. Once I knew what standard I would have to meet, I would get the standard then check to see what other standards the first standard called up.For example - lets say I was designing a multi-meter. I would look at the web and see that my meter needs to meet the Low Voltage Directive, and the EMC directive. The EU maintains a list of standards and I see that I need to meet IEC61010. However, I also need to meet several different parts of this standard - the general requirements section, test leads section etc. Getting the standard, I see that if it contains a rechargeable battery pack, I need to meet another standard, fuses need to meet certain other standard and so on.To answer your specific questions, you will have to get the standard and read it cover to cover in excruciating detail. If you still are not sure then ask at test houses where this will be checked. They will usually happily give guidance in this.

author: fredboivin
author_rank: Regular Contributor
timestamp: March 05, 2015, 06:18:44 pm
content: Thanks!I wish there was a tool where you could just enter the regions and the application and then it would point you at the right set of standards.The methodology you explain it about what I've been doing up until now. I've spent the last several days going through UL-864, ULC-S525, UL-1481, UL-60950-1, etc and I think I am now dying of a melting brain...

author: MK
author_rank: Regular Contributor
timestamp: March 05, 2015, 06:41:33 pm
content: Thats the beauty of standards, there are so many to choose from...
How do you reball BGA? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: December 15, 2017, 07:44:46 pm
content: Is this the correct procedure of rebelling BGA chips with 185 degrees Celsius lead-free solder balls and a “universal” rebelling stencil:1. Place the chip and stencil onto the holder, aligned,2. With a tweezer, place solder balls onto the stencil matching the cleaned pads on the chip,3. Use a hot air gun at 215 degrees Celsius to reflow the chip,4. The chip is reballed once no ball falls off when the chip is flipped.
How do you represent the voltage stability of the supply voltage - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: May 02, 2023, 06:41:18 am
content: Im doing power analysis using a power analyzer tool, with this tool it logs the voltage among others stuff every given amount of time (i set mine to 1sec). When i reviewed the data i noticed that the voltage is not stable, the supply is 240V AC, and the power analyzer records of +- 10V AC. I would like to include this instability to my report. How would i write this in the report?Is there a metric for voltage stability over time? How should i write? I was thinking of writing it in min and max format but that does not really show the time factor, what if the unstability lasted for only 10 minutes and the rest were perfectly stable in the 2 hour recording.Average Voltage : 237. 76 VACMode Voltage: 237.95 VACMin recorded Voltage : 230 VACMax recorded Voltage : 250 VACAny ideas?

author: moffy
author_rank: Super Contributor
timestamp: May 02, 2023, 08:46:52 am
content: Standard deviation is the statistical term for such but I think it is based on a gaussian curve or normal distribution? it has been a while since I last messed with statistics.

author: Jeroen3
author_rank: Super Contributor
timestamp: May 02, 2023, 08:56:11 am
content: You can look at how power quality meters report data (eg: EN50160). They provide a min/avg/max and a histogram.Eg:http://demo.pqube3.com/Example report attached

author: Vovk_Z
author_rank: Super Contributor
timestamp: May 03, 2023, 03:47:22 pm
content: IDK how we can measure its stability with a single number. I guess there isn't one characteristic. The quality of electricity is described by at least 10-20 parameters.If you only measure one parameter (RMS voltage) and it varies by 10 V with rated voltage 230/240 V then it's pretty acceptable, as for me. I mean, until voltage varies +-5% that's totally fine. The voltage varies all the time because the electrical network has some impedance, and everybody turns on and off their own loads.When the voltage varies by 10% and more - that is not so good.

author: TimFox
author_rank: Super Contributor
timestamp: May 03, 2023, 04:00:42 pm
content: In statistics, the "standard deviation" is a statistic for the variation about a mean value.It is the same as the "root-mean-square" or rms variation, and is valid for random distributions, not limited to "normal" or Gaussian distributions.For sine waves, which are not random, the rms value is also well-defined and used to compute the mean power (notrms power, which is useless).In your case, you are measuring the rms value of the AC waveform, averaged over a reasonably short time interval.Over the longer term, that value fluctuates over time due to reasons discussed above.Probably, the most important description for your report is the min/avg/max values discussed by Jeroen3, and the histogram might be useful as well.(In true random variations with a normal distribution, the peak-to-peak variation is theoretically infinite, if you wait long enough, but the standard deviation is well-defined.)
how do you tell which "direction" a signal is going? - Page 1
Forum section: electronics / projects

author: jeremy
author_rank: Super Contributor
timestamp: August 07, 2014, 07:53:10 am
content: Hi all,Every so often, I'd like to know which device is driving a bus and which is listening (assuming there are only two devices), but obviously my logic analyser doesn't really care. It's easy to do if the bus only goes in one direction, but for bidirectional signals like I2C I've never worked out a good way of doing this. Has anyone tried this before? Any suggestions?

author: fcb
author_rank: Super Contributor
timestamp: August 07, 2014, 08:27:38 am
content: Put a resistor in the line.Look for the polarity(direction) of the voltage drop, if you need to do this in your project, then a fast comparator and some logic would sort this out.

author: Precipice
author_rank: Frequent Contributor
timestamp: August 07, 2014, 08:35:08 am
content: On i2c, you can often see who's transmitting by how close to ground it can get the line. (Well, it works OK if you only have 2 maybe 3, devices on the bus. You can deliberately degrade one device if you need - add a few tens of ohms between the device pin and the bus.)But yeah, sticking resistors in buses, if done carefully, can give you some hints. On a long bus, if you can get both ends to the same 'scope, you can spot it with timings, too - driver end happens first.
How do you use a supercap? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: June 22, 2017, 07:08:57 am
content: I have a few supercaps lying in my parts bin, 0.47F 2.5V type. What can I do with them?I know that for higher capacitances (2kF 2.5V or so) I can create a spot welder of my own using a bank of supercaps and a high current MOSFET or thyristor. But 0.47F is too wimpy for that.What can I do with it? Can it be used in place of a coin cell battery for the 1.8V RTC power rail of a chip? If so, how?

author: Zero999
author_rank: Super Contributor
timestamp: June 22, 2017, 07:53:02 am
content: Yes, they can be used in back up applications but the amount of energy stored is tiny, compared to a battery of a comparable size.

author: 5321488
author_rank: Contributor
timestamp: June 22, 2017, 07:53:52 am
content: Look up the joule thief circuit if you are in to the battery style applications of super-caps

author: technix
author_rank: Super Contributor
timestamp: June 22, 2017, 08:06:59 am
content: Quote from: 5321488 on June 22, 2017, 07:53:52 amHey I created the "regulated Joule Thief" shown in Wikipedia...

author: kakabouras
author_rank: Newbie
timestamp: June 22, 2017, 01:44:14 pm
content: A couple of years ago I participated in a university/industry research project where supercapacitors are used in storing energy generated during the descent/braking phase of elevators. The stored energy is returned to the electrical network during the ascent phase.The concept demonstrator had supercaps occupying a volume of more than half cubic meter.
how does a dual n-channel buck converter work? - Page 1
Forum section: electronics / projects

author: ralphd
author_rank: Frequent Contributor
timestamp: December 01, 2015, 11:07:37 pm
content: Most synchronous buck converter circuits I've seen us one P and one N channel mosfet. How do converters like the LM3100 work?http://www.ti.com/product/lm3100

author: Niklas
author_rank: Frequent Contributor
timestamp: December 01, 2015, 11:37:44 pm
content: Have a look at the block diagram on page 8 in the datasheet, especially on the capacitor between BST and SW. When the lower FET is turned on, that capacitor will be charged through the diode between VCC and BST. When the lower FET is turned off, that capacitor will have a voltage of VCC minus one diode drop and it is referenced to the source of the top FET. The potential at the BST pin can be higher than VCC.

author: ralphd
author_rank: Frequent Contributor
timestamp: December 02, 2015, 04:11:51 am
content: Quote from: Niklas on December 01, 2015, 11:37:44 pmThanks. So the capacitor is used for a charge pump to generate a voltage over Vin to drive the high-side mosfet gate?

author: Siwastaja
author_rank: Super Contributor
timestamp: December 02, 2015, 08:39:53 am
content: Quote from: ralphd on December 02, 2015, 04:11:51 amYes. This so-called bootstrap circuitry is extremely widely used. It requires an undervoltage lockout circuitry in the driver to work properly and safely. But typically everything is integrated, expect capacitor (and sometimes the diode), which need to be external. Capacitor because of the largish capacitance needed, and sometimes the diode because of the large reverse voltage spec needed.
How does a flip dot electromechanical indicator work? - Page 1
Forum section: electronics / projects

author: e100
author_rank: Frequent Contributor
timestamp: November 16, 2020, 01:51:43 pm
content: Is the colored disk a magnet with some kind of hinge or pivot? It's difficult to tell from the video because it changes so fast.Is there a coil offset from the axis, and what stops the magnet from freely rotating when the coil is not being energized?https://youtu.be/_xW0PrurLq0?t=74

author: ataradov
author_rank: Super Contributor
timestamp: November 16, 2020, 05:56:34 pm
content: The disc itself is made of a slightly magnetized material, so it sticks to the core of the coil. The holding power of that is pretty weak, on some of them vigorous shaking will mess up the display. I assume the ones used on the buses are a bit more robust.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 16, 2020, 06:37:50 pm
content: https://en.wikipedia.org/wiki/Flip-disc_display
How does a robot vacuum cleaner hit it's dock at a mm accuracy? - Page 1
Forum section: electronics / projects

author: Reider
author_rank: Contributor
timestamp: February 07, 2017, 10:31:25 pm
content: HelloI'm trying to redesign a circuit for my robot vacuum cleaner but the only thing missing is the docking mechanism.The one I have has 3 seemingly IR receiver modules, one at the center and the other 2 slightly to the sides pointing a little bit outward. There is also one extra at the top but receiving at 360 degrees.The docker has 3 IR LED-s always on.I'm guessing each receiver works at a different frequency and somehow measures the strength of the demodulated signal. Can that be done? The problem is that I don't have an oscilloscope.Attached I have the redrawn schematics of the robot IR LED array, and a picture of the docking station LED-s.Thank You

author: Reider
author_rank: Contributor
timestamp: February 18, 2017, 01:23:17 am
content: So finally I got an oscilloscope and was able to figure out how it's done, if anybody is interested.As I mentioned before, the dock has 4 IR leds, 3 in front, and one on top. The robot vacuum has 4 IR mid range proximity sensors, 3 on the front and one on top.First I tough they work at different frequencies (at leat the side ones) but turns out all of them are 38Khz witch now seems to be a really good idea.All 4 LED's give out 8 pulses that I will call a signal. Each signal lasts for 27.4 milliseconds and repeats after 31.6 milliseconds.The first 4 pulses are all the same length for each LED 2.8 ms, and after that the last 4 pulses are either a short one or a long one unique to each LED's location.Signal of the left LEDSignal of the right LEDSignal of the center LEDThe top one will fill in the last blank place, but I'm not including that one.The receiver is a proximity sensor has no part number but I suspect it's something like this one:http://www.vishay.com/docs/82474/tssp4p38.pdfIt has a special feature:QuoteHere the output of the Left and Right receiver, left on the bottom, when the Left one is turned straight to the LED-s and the right one is not facing them.So it works something like that it uses the first 4 strong pulses if it's really far away to detect the location of the docking station, and when getting really close will measure the lengths of the different pulses matching the sides and center to fine tune the movement.The top sensor, the last pulse width can also be used to get proximity, but I suspect it is mainly used to avoid the dock when running around the room and to not hit it.Further investigation is needed, but I think I'm on the right track.

author: MickM
author_rank: Regular Contributor
timestamp: February 18, 2017, 05:45:56 am
content: Hi;Good info - thanks.I have a an older Roomba that I plan to mod.Mick M.