hybridfree/eevblog-posts huggingface dataset:
How good is ATECC508A as a cryptographic token? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: August 21, 2018, 09:34:01 pm
content: In a nutshell, this idea would be building a YubiKey clone of my own, since I have trouble buying YubiKey legitimately in China (due to US export controls.) The centerpiece of the token would be an ATECC508A chip.Questions:1. How good is it? As in how secure is it?2. Is there any standard USB protocol for security tokens like this? Hopefully this standard protocol will allow me to log into my computer using this.3. Do I need a PKI to use it, or can I just rely on decentralized crypto like GPG?4. Recommendations of the fingerprint scanner? Or do I even need one?5. Is it a good idea to put the PCB assembly in a dremmeled USB stick case?6. Is there any good solution for storing and sending sensitive data secured using such tokens? (If GPG can work, this is a no-brainer as it supports both file encryption and S/MIME with PGP. Otherwise...)
How good is this Ultra thin piezo electric blower? - Page 1
Forum section: electronics / projects

author: daslolo
author_rank: Regular Contributor
timestamp: April 30, 2019, 12:56:14 am
content: https://www.mouser.ca/ProductDetail/Murata-Electronics/MZB1001E00?qs=Kb1gBmPnxXYU7W384SY%2FiQ%3D%3DSo thin, so fabulous, is it any good? If you have used it, share your experience.

author: Circlotron
author_rank: Super Contributor
timestamp: April 30, 2019, 01:05:55 am
content: Would be handy if it had integrated drive electronics so the user only had to supply DC. How popular would brushless DC fans have become if we had to produce our own drive circuitry?

author: Tek Tech
author_rank: Contributor
timestamp: April 30, 2019, 01:28:01 am
content: Here's a presentation below.It looks pretty effective for the size but would probably drive dogs, roaches etc nuts.https://youtu.be/aSELxfMa6aY

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 30, 2019, 02:22:12 am
content: Big Clive takes apart a bigger version of it:

author: coppercone2
author_rank: Super Contributor
timestamp: April 30, 2019, 03:50:19 am
content: test your system against their device with a blower with flow and pressure sensors to see how it performs within that curve specified

author: daslolo
author_rank: Regular Contributor
timestamp: May 01, 2019, 03:43:19 am
content: It's just a piezo electric membrane with no driver, not quite the drag and drop cooling solution I was hoping for.
how i repaired old obsolete meter (restore old tech) - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 10, 2023, 11:02:05 am
content: just wanted to share my latest happiness, it feel so good when hard to solve things, actually get solved.the projectRohde & Schwarz ESM 300 VHF monitoring receiver 1961in this video you see the meter repair in detail :https://youtu.be/nBAupJla6Tg

author: KE5FX
author_rank: Super Contributor
timestamp: December 16, 2023, 07:56:10 pm
content: Quote from: oz2cpu on December 10, 2023, 11:02:05 amGreat video. I'd like five minutes alone in an empty room with whoever threw that in a dumpster.What a beautiful piece of hardware!I can't imagine what motivated all that silver-plated shielding around the oscillator tube, but I'm sure they had their reasons. It looks like a million Deutschmarks and probably cost a substantial fraction of it.And nice work on the meter! I was thinking you were a little too quick to blame the meter itself, and then I expected a disaster in the making when you tore into it, but it soon became apparent that you knew what you were doing.
How implement LoRaWAN sensor network???? - Page 1
Forum section: electronics / projects

author: Dhanushka
author_rank: Regular Contributor
timestamp: February 25, 2020, 05:53:04 am
content: Hi,I am currently on a project which is a wireless sensor network based on LoRa modules. So, I planned to use LoRa Ra-02 modules and LoRaWAN protocol with LoRaWAN gateways for eliminate the complex routing schemes (if use general RF module, I have to use a routing protocol for send data from a node as a mesh network but LoRaWAN gateways can handle much more nodes at once. Ido not have good formal backgroundknowledge in RF wireless networking. So, I highly apritiate someone can give me a brief introduction as starting point for technical stuff like,1. How use LoRaWAN protocol on a LoRa module with microcomtroller(Ex: Arduino)?2. Which other modules are suitable for LoRaWAN???Thanks all.
How is a digital input best designed? - Page 1
Forum section: electronics / projects

author: AndersJ
author_rank: Frequent Contributor
timestamp: February 14, 2016, 05:03:56 pm
content: How would a 0-30 Volt, up to 1 KHz digital input to a CPU best be designed,considering ESD, EMC, reverse polarity input protection, etc, etc?In other words, an input that within reason can handle "anything".

author: halexa
author_rank: Regular Contributor
timestamp: February 14, 2016, 05:23:20 pm
content: Check this thread:https://www.eevblog.com/forum/microcontrollers/robust-microcontroller-input-protection/

author: uncle_bob
author_rank: Unknown
timestamp: February 14, 2016, 05:34:51 pm
content: HiWell, a direct lightning strike is inside some definitions of "everything". Is it inside yours?Plug it into the local wall socket is another common definition of "everything". That's a very different level of protection.So moving on a bit:The simple answer is to grab a pair of reasonably rated resistors. The form a simple attenuator. We want to be able to handle 500VDC on a continuous basis (yes that's an odd wall socket). Therefore E^2/R has to be in spec for the resistors. They also need to be rated to 500V. We'll pick 1/2 W leaded parts to keep the voltage rating part easy. If 1/2 = 500x500 /R then R= 500,000K ohms. (yes that calculation could be wrong). I grab a 500K and make it the input R.My gizmo is likely a 3.3V device I need to take 30V down to 3.3. My second resistor will be a bit over 50K. I now have a scaled voltage that my MCU can handle. Next up would be a cap across the 50 K to limit the bandwidth to 1 KHz. A 3.18 nF looks like it will do just fine and it is not to big or to small to be practical.At 500V my 500K resistor will be running at 1 ma. I need to handle that current at the 3.3 V level. I put a nice fast protection diode to ground and another to the supply. You now are clamped at -0.7 and +4.0.Next it's off to look at op-amp spec sheets. Your goal is a part that has input protection information on it. You probably will find that a series resistor after your clamp is useful to keep the amp happy in all cases. That might be 10K, it could be larger or smaller depending on the amp.So it sounds like we have a solution ...What if they plug the *ground* side of the circuit into the 500V? Is that something you need to handle? If so,the approach is similar the circuit details are a bit different.If you have other definitions of "worst case" the circuit will change a bit. You may move zener diodes and clamp diodes into the first resistor leg. You might put a gas discharge device (and a fuse) on the input. You can keep going on and on as you expand the definition of what you expect to see.=======Edit ...Ok I assumed it was analog and not digital. On re-reading I see that's not the case. The op amp needs to drive a comparator or you need a high input impedance comparator. Hysteresis is a real good idea on a slow edge.Bob

author: sarepairman2
author_rank: Frequent Contributor
timestamp: February 14, 2016, 05:43:58 pm
content: you need a security guard to defend it against terrorism
How is handheld multi meter handles over load? - Page 1
Forum section: electronics / projects

author: opa627bm
author_rank: Regular Contributor
timestamp: September 20, 2022, 01:32:34 am
content: Hi All,I have an OLED Agilent handheld DMM that , unfortunately the OLED screen gives up so I took it apart just for fun.I have noticed it is using a CADDOK resistor network for input voltage division. It will work, if your input voltage is low, but what if I put 1000V DC in, that div by 10 output will have almost 100V into the analog mux, how is the meter handles that? for bench, they can use relay to control the range, but for this one not sure how they do it.The CADDOCK resistor has the first resistor break open to connect to the rest , so I guess depends on which dial you use, it will connect a resistor in series but still cant figure out how to handle an overload event..resistor divider, and they use the c48 type.http://www.caddock.com/Online_catalog/Mrktg_Lit/Type1776.pdfRegards,Li

author: Terry Bites
author_rank: Super Contributor
timestamp: September 20, 2022, 06:51:35 am
content: The input impedance of the DVM is 10Meg (typical). At 1000V, 1000/10Meg the input current is 100uA. The protection only has to divert any HV to ground at this low current. A back to back diode post attenuator is the norm.Low leakage diodes are needed and they can be expensive. Its common to see a couple of back to back jfets performing the diode function. Gate leakage is very low. pA for some types.

author: opa627bm
author_rank: Regular Contributor
timestamp: September 20, 2022, 08:05:46 am
content: Quote from: Terry Bites on September 20, 2022, 06:51:35 amHi Terry,Thanks for the response, that make a lot of sense now.can you help explain1. How this circuit works, seems JFET is normally on device, so assume it has the same Vth as MOSFET so it will stop conducting when the input voltage is above ... say 4.5V?2. Can it be replaced with a MOSFET?thank you very much!Regards,Li

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 21, 2022, 03:09:27 am
content: https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg/videosThat should answer how overvoltage protection is done in multimeters and how well it works in practice.
How is set the remaining charge in a power bank - Page 1
Forum section: electronics / projects

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: January 23, 2023, 11:24:47 am
content: Hi All,I have a 10000mAh power bank based on a IP5506 chip.It is an usual one with one USB charging port and two USB ports.The problem is that if the drain power is not sufficient, the power supply shuts down. Not very useful for long term use on a low power device.I thus decided to hook directly on the battery cells by soldering two wire, and added a protection circuit externally. So I am usingthe circuitry of the power bank only for charging.The things that surprises me is that the display of the remaining power stays always to 100 %.I have now power my phone for 48 h continuously without recharging and I still have 100%. The cells are at 3.6 V. Normally they should remain only about 35 %.Do you have any hint ?

author: tooki
author_rank: Super Contributor
timestamp: January 25, 2023, 08:35:05 pm
content: By drawing power directly from the cells, you circumvented the fuel gauge (which is probably built into that IC; I couldn’t find its data sheet in English, but other models from that vendor have it built in). Fuel gauges work not by measuring the battery voltage, but by counting the energy flowing into and out of the battery (so-called “coulomb counting”). This is much more accurate, but relies on ALL energy into and out of the battery flowing through it. By going around it, the fuel gauge has no idea what’s happened, and thus assumes it’s where it last left off.

author: thm_w
author_rank: Super Contributor
timestamp: January 26, 2023, 12:51:59 am
content: Looking at the datasheet:https://datasheetspdf.com/pdf-file/1300685/Injoinic/IP5506/1I don't see any way to keep it alive.Just says:"Automatic shutdown when no load The TloadD load current is continuously less than 45mA = 30s"
How is this -11V regulated - Page 1
Forum section: electronics / projects

author: Miti
author_rank: Super Contributor
timestamp: February 06, 2020, 01:55:24 pm
content: Good day All,I cant really understand how this -11V is regulated in the IFR2025 RF signal generator. Can anybody explain it to me? Shouldn't be a Zenner or something in the base or it is more like a filter? TR202 is the regulator.

author: schmitt trigger
author_rank: Super Contributor
timestamp: February 06, 2020, 02:10:56 pm
content: The circuit shown is clearly labeled "-11v filtering", and not "-11v regulator".The transistor capacitor arrangement is a capacitance multiplier, plus all the other caps downstream.With the limited information afforded by a truncated schematic view, it appears that either:a) the -11v value is only nominal,b) the -11v value has been regulated upstream.

author: Miti
author_rank: Super Contributor
timestamp: February 06, 2020, 04:21:08 pm
content: Thanks for pointing the obvious! I got stuck trying to understand the circuit and didn’t even read the note.The input is -12V and because all the other voltages are properly regulated, I expected -11 to be regulated as well but seems like it is not very critical.Capacitance multiplier... cool.
How Is Time/Date Being Maintained In This Control Box - Page 1
Forum section: electronics / projects

author: bostonman
author_rank: Super Contributor
timestamp: August 17, 2023, 01:27:09 am
content: I'm uncertain how to word the subject line for my question.Recently I got an irrigation system installed and it has a control box to control zones, start time, length, etc... From my guess, storing the program settings is saved in an EPROM.The manual states the system doesn't use a battery, and I didn't see a battery in the system; hence why I assume the program(s) are saved to an EPROM.The confusing thing is the time/date and how it's maintained. I unplugged the unit for a few minutes and it maintained the date/time which implied it has a battery somewhere. In order to stop the system from watering the lawn when it rains, I can only find one way to halt the program from running without unplugging it (ignoring the fact I can edit/delete the program) which is to slide a large black slider switch to 'off'.When I do this, it turns off the entire control box. The first few times I did this, the system was "off" for a good 24hrs, turned it on, and the date/time was still correct.Last week we got excessive rain and I had it "off" for a few days. When I turned it on, the time/date was reset.My question is: how is the date/time being maintained for short spurts, but lost after a few days of power loss?

author: Shonky
author_rank: Frequent Contributor
timestamp: August 17, 2023, 01:32:30 am
content: Supercap? Or even just a largish cap if the RTC is low power enough could last a few days.

author: bostonman
author_rank: Super Contributor
timestamp: August 17, 2023, 01:36:27 am
content: That was the only thing I could guess.If it matters, this is a Hunter HPC-400 Control Box.The online documents on their website shows installation instructions and other stuff, but doesn't discuss much else.
How is torque controlled in Field-Oriented Control ? - Page 1
Forum section: electronics / projects

author: cadena
author_rank: Contributor
timestamp: April 16, 2020, 08:16:37 pm
content: Hi everyone,I am trying to control the torque in an FOC algorithm but I don't know how to. I have seen FOC block diagrams (see attached picture) and I am trying to simulate this in MATLAB but I still don't get how to control torque in my SIMULINK model (see attached picture). Also I don't want a speed loop since I only want to control Torque. Please any help would be greatly appreciated.

author: cadena
author_rank: Contributor
timestamp: April 16, 2020, 08:26:31 pm
content: Note: I am even measuring my motor speed and I get 0 which makes no sense.

author: Wolfram
author_rank: Frequent Contributor
timestamp: April 17, 2020, 08:41:59 am
content: Torque comes from the part of the stator current that is in quadrature with the rotor field. As far as I understand, you should be able to control torque by feeding your desired torque value into the Iq error amplifier (the signal labelled Vq_ref in your diagram).

author: max_torque
author_rank: Super Contributor
timestamp: April 17, 2020, 10:44:34 am
content: Looking at that model,you can't control "Torque" because the model doesn't include a suitable motor model that characterises the torque per amp of the motor.If you just want to simply add that, then just use a fixed constant (ignore saturation etc) and assume that the motor makes 100% of that torque constant when the current is 100% in the q axis, and makes 0 % when the current is in the d axis.ie, assume for your virtual eMachine a value of say 1Nm per Amp in the q axis. If you have 10 amps, all in the q axis, then assume 10Nm, if you have 10 amps total, 5 in q, 5 in d, then the assumed torque is 5Nm etc etcFor a real eMachine, the relationship between current and torque is complex, and control inverters are calibrated on test rigs to determine that characteristic and to map that into the inverter, allowing the end user to demand Torque rather than axis current. That mapping is of course intrinsically bi-directional, so is also used as feedforward to the FoC controller.

author: max_torque
author_rank: Super Contributor
timestamp: April 17, 2020, 10:46:12 am
content: Just looked closer, there is a what i assume to be a load torque being fed into the motor model, so in THAT block there probably is some of the torque estimator stuff?
How it blinks? - Page 1
Forum section: electronics / projects

author: t4rmo
author_rank: Contributor
timestamp: December 12, 2022, 06:53:41 pm
content: Recently, i have bought Christmas lights, I don't understand how they blink without capacitor, any idea?I attach the circuit

author: ealex
author_rank: Frequent Contributor
timestamp: December 12, 2022, 07:10:26 pm
content: hellojust a guess: there is a small capacitor in the 3 pins component.it forms a high frequency oscillator that's divided down to the blink rate.here's an analysis of "flame flicker" led:https://cpldcpu.wordpress.com/2014/03/01/follow-up-on-candle-flicker-leds/

author: Zero999
author_rank: Super Contributor
timestamp: December 12, 2022, 08:55:28 pm
content: The part labelled 706 is an LED flasher IC. There are LEDs available, with it built-in.https://www.eevblog.com/forum/projects/optoelectronics-die-pictures/msg3248254/#msg3248254Here's an example of such an IC, in a through hole package.https://www.rapidonline.com/Catalogue/Product?Id=82-0030
How many reflow processes can a part reliably handle? - Page 1
Forum section: electronics / projects

author: MatCat
author_rank: Frequent Contributor
timestamp: February 28, 2014, 08:36:40 pm
content: I am curious if anyone has any experience with how many times a part can be reflowed before it starts to do damage, I.E. SMD Caps, IC's, resistors, etc? I realize this will vary wildly from one part type to another but I am curious to see what experiences people have had.

author: JoeyP
author_rank: Frequent Contributor
timestamp: February 28, 2014, 09:03:47 pm
content: You're right that it varies dramatically with the specific part. I've seen ICs that would barely survive a single reflow cycle. I've seen others that can survive a remarkable amount of abuse (in particular, certain FPGAs, which can withstand numerous cycles and survive waaaaay more heat than the manufacturer specifies).

author: Alphatronique
author_rank: Regular Contributor
timestamp: March 01, 2014, 01:36:08 am
content: Hinormally 3 re-flow cycle was the normbut less was better specially for led and electrolytic cap ..in doubt refer to datasheet

author: marshallh
author_rank: Unknown
timestamp: March 01, 2014, 01:54:28 am
content: Typically all parts will handle 3 cycles. The larger the package as a general rule the fewer cycles it will survive. This also assumes you have fairly even heating across the part. I'm transplanted some fpgas several times, and had no problems.

author: JuKu
author_rank: Frequent Contributor
timestamp: March 06, 2014, 02:15:01 pm
content: As said three is the norm; if less, the data sheet should tell you. There is a catch: Air moisture will creep in to plastic IC packages; once you open up the factory sealed pouch, you have typically 24 or 48 hours to do reflow, after that you either have to dry the chips or get lucky.

author: poorchava
author_rank: Super Contributor
timestamp: March 06, 2014, 02:42:24 pm
content: most standards tell about 3 reflows. one for either side of the pcb, one for rework.
How many turns for a full stroke? - Page 1
Forum section: electronics / projects

author: atferrari
author_rank: Frequent Contributor
timestamp: November 02, 2014, 12:27:22 am
content: For any of these linear actuators,http://www.portescap.com/sites/default/files/35dbm_l_specifications.pdfhow many turns it takes to ecercise a full stroke?

author: calzap
author_rank: Frequent Contributor
timestamp: November 02, 2014, 01:27:34 am
content: The diameter of the threaded rod is 3.5 mm, also listed as 0.136 inches. Maximum travel is listed as 63.5 mm or 2.5 inches. A common pitch for 3.5 mm is 0.60 mm. Threads per mm is 1/pitch. Rotations for full travel are full travel distance x threads per unit distance. In this case in metric: 63.5 x 1/.6 = 106 rotations. In the inch system, dimensions of the threaded rod match #6 machine screw thread, but you would need to know the TPI. Common TPI's for #6 are 32 and 40. Rotations for full stroke would be maximum travel, 2.5 inches, x TPI. So that's 80 rotations for 32 TPI or 100 rotations for 40 TPI. Try to get pitch specs for the threaded rod.Mike in California

author: atferrari
author_rank: Frequent Contributor
timestamp: November 02, 2014, 01:34:03 am
content: Quote from: calzap on November 02, 2014, 01:27:34 amGracias Mike. The key word is pitch.
How many USB-C hosts (downstream devices) provide 500mA, vs 1.5A, vs 3A. - Page 1
Forum section: electronics / projects

author: rf-fil
author_rank: Regular Contributor
timestamp: February 26, 2024, 04:24:25 am
content: I'm working on something that's being charged by USB-C. I'm debating if I can simply avoid support for 500mA, or even 1.5A devices. My gadget uses a fair bit of power, and if the charger only gave me 500mA, I'd have to manage the internal power consumption in a complicated way.. I'm thinking to disable charging, and signal "wrong charger" to the user somehow, unless I get 3Amp-capable downstream device. (This is easy to detect with the CC lines in USB-C.)I don't recall ever seeing a USB-C wall plug that is less than 3A. But, I'm not sure about laptops, PCs, etc. My laptop supports 3Amps on its USB-C port, as far as I can tell.

author: jbb
author_rank: Super Contributor
timestamp: February 26, 2024, 05:52:23 am
content: I feel your pain there. You try to search for the info and all you get is “USB supports charging up to 100 Watts!”If it helps, MacBooks seem to do 5V 3AOn the too-low-current front, I’d be quite surprised to find anything which was 500 mA only (barring a USB A -> C adaptor cable). In fact, it just might be that the USB C standard requires minimum 1.5A from Power Sourcing Equipment (PSE)…

author: SiliconWizard
author_rank: Super Contributor
timestamp: February 26, 2024, 06:20:54 am
content: The answer is (maybe) in the USB Type-C spec, which is free to download. But not particularly digestible.QuoteThis is defined in "USB Type-C Current" and all USB Type-C sources have to support this. As with many standards writing, it can be a tad confusing. But the very fact a given source is able to advertise the max current it can supply to a sink is IMO an indication that it doesn't have to be able to supply any of the profiles above the default (500 mA or 900 mA). It just has to advertise what it can do.It's probably very rare though at this point that any USB-C source would not be able to deliver up to 3A, as you noticed. Now for any compliant device, if you do detect it via CC lines as you intend to do, then you'll have no problem. But again, from the phrasing in the standard and common sense given the different levels that are specified, it can be expected than *some* sources may not be able to deliver 3A. The question of how many, good luck finding any answer to that.One kind of product on which I would *suspect* not necessarily being able to get 3A is typically mobile phones when used as USB sources. Maybe also some smaller tablets. Other than that, a large majority of laptops and USB-C "chargers" should support at least 5V/3A, and many of them also support USB-PD at various levels.
How much a battery last in the new HP Prime: ultra cheap/simplistic testing rig - Page 1
Forum section: electronics / projects

author: Erwin Ried
author_rank: Regular Contributor
timestamp: November 08, 2013, 04:18:21 pm
content: The new HP Prime removes a lot of the advanced and confusing features from the lovely 48 series (and the derived ones like 49g+, 50g), but they remove so much things than you can't even control system flags or any advanced stuff.Since nobody knew the real representations of the battery indicator in the screen related with the real battery level or the battery duration itself, without having a way to avoid the calculator powering off because inactivity I just placed a micro servo pressing the keys every 1 minuteAnd the results:For all the other measurements I want, like other brightness levels, high CPU, powered off I ordered the parts and pcbs to buildhttps://bitbucket.org/jmedved/usbamps/wiki/Partsand then remove the lipo from the HP and directly measure the power usage (and in that way extrapolate all the other measurements having this one as base).Is this a correct way to measure battery durations? Or there is some weird phenomena in the lipo batteries that will prevent me from getting a real result reading the USB current?
How much does LTZ 1000 weight? - Page 1
Forum section: electronics / projects

author: fonograph
author_rank: Frequent Contributor
timestamp: March 05, 2018, 10:51:36 pm
content: Do you have LTZ 1000 voltage reference that isnt soldered to something? Do you have decently accurate weight scale? If both of your answers are yes,then please,weight it and post your results in this thread!

author: Zero999
author_rank: Super Contributor
timestamp: March 05, 2018, 11:40:19 pm
content: Just one question: why?

author: hugo
author_rank: Regular Contributor
timestamp: March 06, 2018, 12:23:05 am
content: He's probably trying to determine that the one he has is a genuine one or not ...

author: fonograph
author_rank: Frequent Contributor
timestamp: March 07, 2018, 02:49:58 pm
content: I am just curious.Problem I have with electronic components that often the datasheet contains everything imaginable except weight,I want to have total knowledge about LTZ1000 and I failed find any official weight.Furthermore,I noticed weight of electronic components is often inaccurate,something that is 47g in one place,is 45 in another for example,so its hard to believe either of these numbers.if someone weighted it,thats information I would trust.

author: m98
author_rank: Frequent Contributor
timestamp: March 07, 2018, 06:00:18 pm
content: Send me an LTZ 1000 and I can give you the mass accurate down to 1mg.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 07, 2018, 06:43:56 pm
content: Quote from: fonograph on March 07, 2018, 02:49:58 pmif specification says 45g ±5g which one would you trust?

author: fonograph
author_rank: Frequent Contributor
timestamp: March 07, 2018, 09:05:53 pm
content: Quote from: Mechatrommer on March 07, 2018, 06:43:56 pmThere is big difference between weight specification of object that is manufactured in way that weight is highly consistent so the specification gives only one definitive number that would in 99.999% of weight measurement come exactly as specified and objects or items that have large random differences from item to item becose they are fundamentaly physicaly inconsistent so the weight is given in average value + plus minus random variation,semiconductor devices are not bananas ( atleast when it comes to mass ).

author: ogden
author_rank: Super Contributor
timestamp: March 07, 2018, 09:43:51 pm
content: Quote from: fonograph on March 05, 2018, 10:51:36 pmRight. While you are weighing - could you please lick it as well? I would like to know it's taste.

author: splin
author_rank: Frequent Contributor
timestamp: March 07, 2018, 10:07:41 pm
content: LTZ1000CH .98g Claimed accuracy is +/- .02g but neither of my two scales have been calibrated. FWIW they both gave exactly the same reading.

author: fonograph
author_rank: Frequent Contributor
timestamp: March 07, 2018, 11:08:50 pm
content: Thank you splin <3
How multiple users can edit single layout file simultaneously ?  - Page 1
Forum section: electronics / projects

author: Sai teja
author_rank: Regular Contributor
timestamp: February 01, 2018, 04:32:46 pm
content: Hi,I would like to know how multiple people can work on PCB design simultaneously. And I would like to know how is this tackled in established industries. Please through some light on this topic .

author: Jeroen3
author_rank: Super Contributor
timestamp: February 01, 2018, 08:05:59 pm
content: They do not. One person works the board.Or, if you are the lucky guy at that isn't forced to work with outdated software, there are merging and collaboration features.http://www.altium.com/video-altium-presents-pcb-collaboration

author: AndyC_772
author_rank: Super Contributor
timestamp: February 01, 2018, 08:15:53 pm
content: https://www.cadence.com/content/cadence-www/global/en_US/home/tools/pcb-design-and-analysis/pc-design-flows/product-creation/allegro-pcb-designer-team-design-option.htmlhttps://www.cadence.com/content/cadence-www/global/en_US/home/company/newsroom/press-releases/pr/2017/cadence-allegro-pulse-extends-team-collaboration--reducing-costs.html
How must be grounded a battery operated DUT when testing ESD immunity? - Page 1
Forum section: electronics / projects

author: mcinque
author_rank: Unknown
timestamp: August 22, 2014, 07:34:46 pm
content: I'm a bit in confusion. Attached here you'll find a typical setup for the ESD immunity test.During the test, a grounded DUT like a desktop PC is grounded by the mains plug. Ideally, the ESD applied to the DUT travels thru the device chassis and discharges to the mains earth.But how to connect anungroundedbattery operated DUT?Literature suggest to connectthe bleeder cable to the ground of the battery operated DUT, to discharge the electrostatic event before applying the next pulse (otherwise without discharging, due to capacitance, the 2nd pulse would be much more higher).But where to put the other end of the bleeder?Only to the ground reference plane?Or to the mains earth?The ESD gun earth cable goes to mains earth, so how can the pulse discharge to the earth ground of the ESD gun if it travels only until the ground reference plane?Floors are NOT always grounded... what I am missing?

author: Neilm
author_rank: Super Contributor
timestamp: August 22, 2014, 09:33:59 pm
content: I believe that the ground reference plane should be a conductive surface connected to ESD return. Therefore your bleeder should be connected to mains earth

author: mcinque
author_rank: Unknown
timestamp: August 22, 2014, 10:11:20 pm
content: Ground reference plane, horizontal plane and vertical plane ARE effectively metal conductive surfaces (tipically cheap alluminium or steel sheets).Me too guess that the bleeder should be connected to mains earth, but I'm not sure about this and I need a couple of opinions.Thank you for giving me yours!

author: Andreas
author_rank: Super Contributor
timestamp: August 23, 2014, 05:35:10 pm
content: Quote from: mcinque on August 22, 2014, 07:34:46 pmThe ESD test shall simulate typical handling issues.So do not try to create a situation which is not possible during normal operation.So if the DUT is battery operated and has no external wiring:Just try to discharge at "typical" handling points.Additional you will have to discharge to the horizontal and vertical grounded plates to simulate the magnetic field of a ESD which happens "nearby".With best regardsAndreas
how old USB exactly works - Page 1
Forum section: electronics / projects

author: msuffidy
author_rank: Frequent Contributor
timestamp: September 23, 2024, 05:58:48 am
content: So I have been trying to figure out the best way to plug in USB devices so they get the most bandwidth. I notice one big problem is there are low speed devices like 1.5M devices. You go oh well they are just mice or something and not a problem. So what I am wondering is under a single root, do these slower devices block the other devices as they transfer? Ideally what you would get is the hub above would re-transmit the data at its higher rate. If that is the case then all this can work. Why do I feel the slower devices are probably messing up bandwith?

author: magic
author_rank: Super Contributor
timestamp: September 23, 2024, 06:45:14 am
content: Quote from: msuffidy on September 23, 2024, 05:58:48 amTry different things and see what gives the most BW to the device you want.Quote from: msuffidy on September 23, 2024, 05:58:48 amYou "feel" because you don't know because haven't tested anythingThe short answer is "it's complicated, but rarely a problem in practice".

author: Ian.M
author_rank: Super Contributor
timestamp: September 23, 2024, 07:31:11 am
content: I had exactly this problem way way back in Y2K. The Alcatel USB ADSL modem couldn't share a root hub with any low speed USB device - IIRC it would either drop or seriously degrade the connection if the low speed device was active. This was on a Pentium II under Win98 OSR2.Since then I've tried to keep keyboards and mice on separate root hubs to other USB devices.

author: magic
author_rank: Super Contributor
timestamp: September 23, 2024, 08:57:13 am
content: Yes, full-speed devices share bus time with low-speed devices, and Pentium II sounds like USB 1.1 era. That being said, I would be surprised if a keyboard or a mouse consumes more than a few percent of available time, so maybe there was something dodgy about your hardware or drivers.On USB 2.0 systems, LS and FS devices are managed separately from HS devices. And if they share an external hub, the hub contains a "Transaction Translator" which means that packets to/from LS/FS devices are sent at HS between the hub and the host controller, so little link bandwidth is wasted on them and HS devices on the same hub don't suffer too much.On USB 3.0, SuperSpeed devices are completely separate (including physical wires) from everything else, and FS/LS devices are attached to the HS bus and supported once again by TTs.So the most problematic case is LS and FS, both on the same hub (root or not). Unless it's a fancy hub with multiple TTs, then it can carry out multiple FS/LS transactions on different ports at the same time.
How overvoltage tolerant are 50 Volt 0805 ceramic capacitors? - Page 1
Forum section: electronics / projects

author: AndersJ
author_rank: Frequent Contributor
timestamp: March 02, 2016, 12:21:09 pm
content: A input surge protection 33 Volt varistor clamps at 90-100 Volts when a 1 kV surge pulse is applied.The next stage has a 0805 ceramic 1 nF capacitor rated for 50 Volts.How tolerant is such a capacitor to a 20 us long, almost 100% overvoltage pulse?

author: bktemp
author_rank: Super Contributor
timestamp: March 02, 2016, 12:47:13 pm
content: If the rise time is fast enough, the MLCC could fail due to Electro-mechanical breakdown:http://www.koaspeer.com/pdfs/MLCC.pdfA NPO should be more robust than X7R.

author: AndersJ
author_rank: Frequent Contributor
timestamp: March 02, 2016, 04:28:35 pm
content: Many thanks for this excellent document.It answers all my questions.Anders J
How repeatable is sample-to-sample Delta Sigma ADC timing? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: March 02, 2018, 05:45:36 pm
content: I get the impression that there seems to be uncertainly over 'when' a sample is taken with delta sigma.Basically I need precise sample-to-sample timing, 240 SPS or better. How can I work this out from a typical DS?

author: MasterT
author_rank: Frequent Contributor
timestamp: March 02, 2018, 07:24:37 pm
content: Depends on a part number. Microchip says for MCP3422 & MCP3550 there is no timing to settle Sinc filter, so basically its easy to use. Sample is timestamped at the request. But TI and almost anyone else specify in DS 5-6 samples to settle Sinc. TI has app. note on this matter.http://www.ti.com/lit/an/slyt264/slyt264.pdf

author: danadak
author_rank: Super Contributor
timestamp: March 03, 2018, 08:49:52 pm
content: Do you need resultant to be in synch or the time the S/H in A/D takes its sample ?Regards, Dana.
How sense weight? - Page 1
Forum section: electronics / projects

author: docmur
author_rank: Regular Contributor
timestamp: May 03, 2017, 12:05:08 am
content: Hey GuysHas anyone ever had to sense weight?I'm just wondering for a silly little quick side project I want to do, if I can throw weight sensing into the system. I was looking if a single chip IC exists which can do this, I only need resolution between 0.1g and maybe at the absolute upper limit 1kg. If anyone's done this, what is the best way to go about it?Thanksdocmur

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 03, 2017, 12:18:06 am
content: Strain gauge technology is commonly used to measure weight.It is difficult to be any more specific in the absence any relevant details.

author: docmur
author_rank: Regular Contributor
timestamp: May 03, 2017, 12:22:16 am
content: Fair enough, I want to put something about the size of a 125 Mason jar on top of it, then measure the contents of the jar. Realistically the jar would never have more then at the most 14g in it. The jar wouldn't move but the contents might change at any time, although slowly.

author: docmur
author_rank: Regular Contributor
timestamp: May 03, 2017, 12:27:44 am
content: I think something like this would work actually:http://www.interlinkelectronics.com/datasheets/Datasheet_FSR.pdf

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 03, 2017, 12:28:48 am
content: These might be of interest....SparkFun OpenScalehttps://www.sparkfun.com/products/13261https://youtu.be/HZtXN-KcssA

author: docmur
author_rank: Regular Contributor
timestamp: May 03, 2017, 12:38:38 am
content: CoolThanks!
How sensitive are thermal diodes to noise? - Page 1
Forum section: electronics / projects

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 19, 2013, 07:41:13 pm
content: I'm using some diode connected 3904s and a few TMP513s to sense temperatures inside a packaged air conditioning system. The maximum length of wiring is about 1ft, done with twisted pair and it's all inside a metal case. Would I need to use the filters suggested in the TMP513 datasheet or would it be fine to leave them out? The compressor is not inverter drive but if I did add in inverter drive, would the filters be necessary?

author: PChi
author_rank: Frequent Contributor
timestamp: December 19, 2013, 09:59:32 pm
content: The THM513 is using a pretty low current so the circuit is fairly high impedance so is likely to be susceptible.I don't know, too many unknowns to be able to answer and I don't have any experience with the part. Some questions are:-How accurate do you want the measurement to be?How electrically noisy is the environment?What are the consequences of say a GSM transmission interfering and rectifying in the transistor base emitter junction causing erroneous measurements?How electrically noisy is the Inverter drive? I expect major variations between models.Any wires passing through the metal box walls will couple interference. If the box doesn't have a well electrically connected lid it's effectiveness would be in doubt. If the metal isn't continuous it tens to just redistribute RF energy not exclude it.It's not possible to quantify the effects (in the real world) so just give it a try.
How should a membrane keypad with joystick be designed? - Page 1
Forum section: electronics / projects

author: Corporate666
author_rank: Unknown
timestamp: June 04, 2024, 12:58:03 pm
content: I just received some membrane keypads from a supplier - they are made correctly to the spec but they don't feel very good and I am wondering what the fix is.The keypad has a "joystick" on one side, consisting of a metal post which is molded inside the rubber part that goes over the whole assembly. That stiffener pushes against dome switches attached to a flex PCB, which sits on top of a stiffener plate.The problem is that there is way too much play on the metal stiffener post inside the joystick... specifically the base of it wobbles around and when you push the joystick to actuate the switch the whole front of the rubber overlay around the stiffener post stretches upwards a bit. It just doesn't feel tight and precise, it feels wobbly and imprecise.I feel like there should be something else in the assembly - either a plate with a hole in it that goes on top of the joystick post to "hold it down" and constrain it's motion along up and down along the axis of the post, or maybe there should be discs laser welded to the back of the 2 pins that protrude through the metal stiffener plate to stop the post from lifting up when you actuate it.I have worked with membrane keypads a lot in the past but I haven't ever done anything with a joystick, so I don't know what best practices are for this sort of design. Maybe just the rubber overmolding should be thicker so it's less stretchy when using the joystick? Or something else?
How square should a 300kHz square wave on a HP204D be? - Page 1
Forum section: electronics / projects

author: RAPo
author_rank: Super Contributor
timestamp: May 16, 2023, 05:44:56 pm
content: My latest addition to my collection op HP instruments arrived today: an HP204D.The square wave is really nice until I get in the 300kHz range, see the picture.Should I be worried, or is this normal?

author: TimFox
author_rank: Super Contributor
timestamp: May 16, 2023, 05:50:14 pm
content: If I read the display correctly, the rise time (about 500 ns) is the same at both frequencies, but (of course) the time/div is lower on the higher frequency display.This is normal.

author: RAPo
author_rank: Super Contributor
timestamp: May 16, 2023, 05:55:27 pm
content: yes, rise time is about equal. Thanks.

author: RAPo
author_rank: Super Contributor
timestamp: May 16, 2023, 06:04:53 pm
content: Found a nice article:"Characterization Method Using Square Wave Signals for Testing Current Transducer Responses"Something for the upcoming holidays.
How standard are USB footprints - Page 1
Forum section: electronics / projects

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: January 04, 2019, 12:08:37 pm
content: I have a bunch of USB devices at home that require frequent plugging in and out and moving around. As a result, in a number of locations I have a bunch of different USB cables at all times, to match each of the connectors. It would be interesting if I could change all of these devices to one single connector (preferably USB-C as the phone and laptops are by far the hardest to change).So how standard are these footprints. Can I just get USB-C connectors with only the USB2 pins enabled?

author: Richard Crowley
author_rank: Super Contributor
timestamp: January 04, 2019, 01:04:01 pm
content: What about one of those magnetic schemes?https://www.amazon.com/Kript-Generation-Magnetic-Micro-USB-Interface/dp/B076PZK3T3

author: fchk
author_rank: Frequent Contributor
timestamp: January 04, 2019, 01:22:47 pm
content: Quote from: TheUnnamedNewbie on January 04, 2019, 12:08:37 pmJust replacing a Type B Micro socket by an USB C socket won't work - neither as host or device. You will need extra circuitry for making an old USB2 device USB-C compliant.There is a lot of documentation to read. For a quick start:http://www.ti.com/lit/wp/slly017/slly017.pdfhttps://training.ti.com/tikit-reference-design-how-convert-usb-usb-cUSB Power delivery is a quite complex topic on its own with many 1000 pages of specification.fchk
How strong is the solder paste surface tension? - Page 1
Forum section: electronics / projects

author: poorchava
author_rank: Super Contributor
timestamp: March 27, 2015, 07:47:45 am
content: I'm working on a design, that involves several stacked PCBs, which are connected with curface-mount 1.27mm pitch high pin count (50 pins) headers. Supplier for the connector is not known yet, but they will be similar to 20021321 series from FCI.The question is: I have those connectors on both side of the PCB, will the surface tension be strong enough to prevent connectors from falling off the bottom side of the PCB during second reflow or should I specify some sort of glue to hold them in place?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 27, 2015, 03:23:48 pm
content: During what process, a second reflow?It could be calculated, I think, but my instinct says it will fall.I don't think components necessarily need to be glued for reflow, but under a wave soldering step, they do.You could also hand solder the bulkier components after the fact, assuming the pins are hand-solderable of course.Tim
Wrong TC3 measurements on transformer - Page 1
Forum section: electronics / projects

author: GelatinCapacitor
author_rank: Contributor
timestamp: July 24, 2024, 06:30:51 am
content: I bought the LCR-TC3, assuming it's the follow up to the TC1 and TC2, even though I could find almost no information about it.Anyway, I tested many things with it. But here is the main transformer from the NSX-SZ20:I tested the secondary coils and got some interesting values:12 - 13 : 190nH 0.6Ω Q0.113 - 14 : 80nH 0.5Ω Q126 <- Too high Q14 - 15 : 65nH 0.5Ω Q0.115 - 16 : 39mH 0.7Ω Q4.4 <- Way higher inductance and higher Q than (12-13)12 - 14 : 115Ω <- Where is my inductance? Too high resistance14 - 16 : 192mH 1.1Ω Q4.312 - 16 : 1.82H 1.9ΩI assume the tester won't be able to properly measure all components.Yes, the results are repeatable. The tester was calibrated with the jumper it comes with and measures the colored hooks as ~0.1Ω each. I also made the tests as calibrated with the hooks and basically exact same results.Yes, the transformer is working correctly. The secondaries deliver the rated voltages and currents. L&R are symmetrical. The output voltages are as expected and drop by the same amount under load on both sides. Just Like the LCR tests I tested each part of the coils with a 22Ω resistive load and measured the voltages and concluded that L&R are symmetrical.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 24, 2024, 10:42:12 am
content: how what ?and to help, you should have used pins descriptionlike this :11 - 17 full winding12 - 16 full winding12 - 1312 - 1412 - 151 - 3 full winding1 - 24 - 6 full winding5 - 6 this one is special you have a thermal fuse = ohms testslh ll rl rh ...

author: GelatinCapacitor
author_rank: Contributor
timestamp: July 24, 2024, 05:25:34 pm
content: Sorry.Used the number pins. Pointed out the unusual:12 - 13 : 190nH 0.6Ω Q0.113 - 14 : 80nH 0.5Ω Q126 <- Too high Q14 - 15 : 65nH 0.5Ω Q0.115 - 16 : 39mH 0.7Ω Q4.4 <- Way higher inductance and higher Q than (12-13)12 - 14 : 115Ω <- Where is my inductance? Too high resistance14 - 16 : 192mH 1.1Ω Q4.312 - 16 : 1.82H 1.9Ω

author: JohanH
author_rank: Frequent Contributor
timestamp: July 24, 2024, 07:55:27 pm
content: I think you have too high expectations for this simple meter. It's a clever device for its purpose, but if you want to measure your use case more reliably, you probably need an LCR meter or use other methods.

author: GelatinCapacitor
author_rank: Contributor
timestamp: July 24, 2024, 08:55:54 pm
content: *sad inductance measuring desires noises*