hybridfree/eevblog-posts huggingface dataset:
choosing a transistor - Page 1
Forum section: electronics / projects

author: kjn4685
author_rank: Regular Contributor
timestamp: August 28, 2014, 02:46:49 am
content: I would like to know if I had a transistor with 50 vcbo and another with the vcbo 100 vcbo will work. The veco is 120v

author: TheRuler8510
author_rank: Regular Contributor
timestamp: August 28, 2014, 03:22:29 am
content: You need to look at other parameters like hfe.What is the application? Everything depends on that.

author: Mike Warren
author_rank: Unknown
timestamp: August 28, 2014, 03:23:47 am
content: If all other specs are the same, then yes, but I doubt that would be the case. Other than that, compatibility is largely dependent on the application.Can you post what the 2 transistors are and what its use is?

author: David Hess
author_rank: Super Contributor
timestamp: August 28, 2014, 04:52:32 am
content: Quote from: kjn4685 on August 28, 2014, 02:46:49 amAre you sure you did not get those reversed? I have never seen a transistor where the Vceo was greater than the Vcbo.Except in very specialized applications like avalanche mode switching, increasing the Vcbo will not affect circuit operation although higher voltage transistors are often slower or have lower gain.
Choosing a TVS and ESD testing - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: March 20, 2021, 04:55:17 pm
content: Hi,apart from the breakdown voltage rating, uni/bi-directional, how do you choose a TVS?Only via the energy it can handle? If so how do you pick one for consumer devices?The current rating is also given, how does that come into play to pick one?Separate but related...Also, when doing ESD testing for consumer electronics, do even the tests/standards (from the least to the most stringent) require the ESD gun to discharge into the pins of a connector? Or only on the connector metal shield (if present)?If it requires to discharge into the pins too, is that only for connectors large enough where you can touch the pins or even in connectors like micro USB?Thank you
Choosing adjustable buck converter for light dimming - Page 1
Forum section: electronics / projects

author: stennic
author_rank: Newbie
timestamp: March 09, 2020, 10:26:45 am
content: Hi,Long story short: I'm trying to find a suitable regulator for dimming LED:s in a boat. The boat previously had halogens with a simple potentiometer dimmer. The bulbs were replaced with voltage-regulated dimmable LED:s. However, as expected, the old dimmer isn't suitable for the low-current LED:s. First, I looked into replacing the pots, but with the relatively high power dissipation in a semi-enclosed space, I realized that the approach probably wasn't suitable.PWM-controlled LED:s could be an option, but flickering is a problems since the frequency would have to be low because of RF-interference.Now I'm searching for a suitable buck-converter module, but find myself lost in the jungle of options. My two worries: low enough "forward voltage" ie, 1.5V drop won't allow full brightness on half-full batteries. The other is output noise - there is VHF and FM-radios close to the dimmers and interference is understandably unwanted.Switching converters would allow for better efficiency and lower Vf (if i understand correctly), while linear converters wouldn't be noisy. However, my understanding is, that for example the LM317 has a Imin of over 1A and a Vf of 1.5V, and the dissipated heat would have to be accounted for.Vin: 12.5-13.5VVout: around 7-12VImax: around 170 mA @ 12V - drops to 4.2mA @ 8.2VI haven't got around to building my adjustable PSU yet, so the measurements were done using power bricks and resistors, therefore the missing values at lower voltages
Choosing an Efficient V Reg. Configuration for Dynamic Supply V and Load Current - Page 1
Forum section: electronics / projects

author: bendras
author_rank: Contributor
timestamp: October 14, 2019, 12:51:25 pm
content: Choosing Efficient Volt. Reg. Configuration for Dynamic Supply V and Load CurrentMy goal is to charge a super capacitor C1 (30mF) from an unregulated voltage source Vbat via a voltage regulator (or a bunch of them) V_REG in an efficient way (say 85% efficiency and above). With the following constraints:1) At any given time voltage of the Vbat can vary between 1V and 6V and it's series resistance can vary between 100 Ohm and 500 Ohm.2) Vout of the V_REG block needs to be 2.5VUsing an LDO would not satisfy the efficienty requirement, hence my guess is that some sort of buck/boost solution should be used.Does anybody have buck/boost chips, combinations of such chips or any other solutions in mind that might suit this problem?Basic schematic of the above:
Choosing and Installing the Correct Connectors/Cables - Page 1
Forum section: electronics / projects

author: beeboopbeep
author_rank: Contributor
timestamp: August 25, 2017, 11:44:07 pm
content: Hi everyone,I was wondering if there are general guidelines and standards when choosing connectors and socket to socket cables for products. For example, if you have a connector that takes in USB 2.0 (4-pin) input and you need to connect this connector to your main PCB (let's say a distance of >50 mm), which cable and connectors would you choose to make the connection? My initial thought was there must be a 'proper' cable for USB since it transfers data relatively quickly. My next thought was distance should matter in this case with regards to signal integrity so that must be taken into account as well.Another example but different situation would be high DC current for power connectors and cables where a high capacity battery needs to be connected to the main PCB.If there are books or articles on these matters that you use as your 'go to' guide, could you please share them?

author: Rerouter
author_rank: Super Contributor
timestamp: August 26, 2017, 12:46:07 am
content: If you have ever assembled a pc, you would have seen that they connect the front panel usb 2.0 via a 30-50cm loom that terminates into 0.1" headers. For this task it is more than sufficient so long as you follow what they are doing.

author: kalel
author_rank: Frequent Contributor
timestamp: August 26, 2017, 12:49:26 am
content: Quote from: Rerouter on August 26, 2017, 12:46:07 amI never compared the voltage drop of front panel vs back panel, might be interesting information.This should depend on the quality of the connector cable the manufacturer has chosen.

author: SeanB
author_rank: Super Contributor
timestamp: August 26, 2017, 10:16:33 am
content: I find the loom just barely gets above the minimum voltage levels on the front panel at 500mA draw, giving a 4.75V supply at the socket at 500mA in most cases, even though the unloaded voltage on the motherboard will typically be slightly above 5V as most PC PSU manufacturers up the supply voltage slightly to allow them to skimp on the copper in the cabling inside, so that they meet the 5V spec on the motherboard connector at full load ( well, at least briefly, most PSU 's are not going to supply that for long anyway without blowing up or just cooking the capacitors to death anyway) and do not have to use a sense line but use that as part of the overall copper/CCA cable. Motherboard connectors will have a lower drop though, often sitting at slightly above 5V0 most of the time, as they have typically a good ground plane connection and a good 5V supply plane connection, with possibly a polyfuse or just a zero ohm link in place of the fuse adding around 0R5 of resistance.

author: viperidae
author_rank: Frequent Contributor
timestamp: August 26, 2017, 09:50:35 pm
content: Even front panel USB 3 goes through 0.1" headers. As long as the power wires are thick enough and the data lines are shielded and the same length you should be ok.
Choosing appropiate replacement for MOSFET - Page 1
Forum section: electronics / projects

author: cRash1001
author_rank: Contributor
timestamp: March 29, 2022, 12:38:02 am
content: Hi,I am having a bit of a problem choosing alternatives for a pair of MOSFETs on a Li-Ion charger based on LTC4006-4.The MOSFET pair I am currently using is DMC4050SSD and I am trying to analyze if ZXMC3A16DN8 can be used as an alternative without modifying the switching characteristics of the current circuit. The problem is the datasheet of these components have their Gate-Charge Characteristics for different operating conditions.DMC4050SSD's Gate-Charge Characteristics is given only for Vds=20V, Vgs=10V and Id=12A andZXMC3A16DN8's Gate-Charge Charactersitics is given only for Vds=15V, Vgs=5V and Id=3.5A.I need to check against operating conditions with Vds=24V, Id=2.45A and Vgs=4.5V.Could someone please help me with how do I get the Gate-Charge Characteristics of these MOSFETs at the desired operating conditions?Some details of the circuit:Input Voltage: 24VOutput Voltage: 16.8VI pk-pk = 2.45AFsw = 300kHzThanks.

author: moffy
author_rank: Super Contributor
timestamp: March 29, 2022, 01:00:22 am
content: The ZXMC3A16DN8 seem slightly better than the DMC4050SSD except for the lower breakdown voltage of 30V vs 40V. With a 24V input I would look for something with at least 40V breakdown voltage, but it's your choice.
Choosing between Bluetooth 4.0 and Classic - Page 1
Forum section: electronics / projects

author: Twistx77
author_rank: Regular Contributor
timestamp: September 02, 2013, 08:02:03 am
content: Hello,I'm working in a device which is already working using a cable but now I need to add a Bluetooth link so you don't need to use the cable. The devices is battery powered but I don't know exactly which kind of Bluetooth I should use.I know that 4.0 or BLE is better for battery powered devices but I'm not sure if BLE will give me enough bandwidth for my application and also if BLE can send data continuously. I've read that the throughput with BLE is about 250kb/s which is just enough for my application since I'm already using 256kb/s with the cable. The thing is, will this speed vary too much with distance ( I only need 10 meters at the most).So can BLE meet my requirements or do I need to use classic bluetooth?I would appreciate any help.Thank you!

author: purfield
author_rank: Regular Contributor
timestamp: September 04, 2013, 08:15:47 pm
content: I'm a total newbie here, but I've been playing around with BLE for a few months and from my experience, I would suggest that you go with classic bluetooth. BLE seems to only be really power-efficient for very low bandwidth applications. I've played around with some BLE development devices transmitting lots of sensor data at high sampling rates, and I can eat through a coin cell battery in just a few hours. On the other hand, if you're transmitting tiny packets at very slow intervals, you can get a few years of use out of a coin cell battery. It sounds like for your application, classic bluetooth would be the best choice.

author: andyturk
author_rank: Frequent Contributor
timestamp: September 05, 2013, 03:13:05 am
content: The main difference between BLE and classic is that BLE keeps the radio off most of the time. That's good for battery life, but not so good for throughput. As purfield said, if you need to send a lot of bits, then classic is the way to go.The real-world throughput of a BLE connection is a lot lower than 250kb/s. The actual number is dependent upon the "connection interval" which is determined by the slave side of the connection. Most likely, your gizmo is actually the master, so the other end determines how often the radios turn on and send bits. When they do turn on, BLE limits you to 23-byte packets.On the other hand, BLE is handy if you're talking to iOS devices, which require a special crypto chip from Apple for classic. iOS devices will talk BLE without the crypto.
Choosing between Different Capacitance Crystals - Page 1
Forum section: electronics / projects

author: DrMag
author_rank: Regular Contributor
timestamp: March 16, 2017, 10:42:42 pm
content: I have a question about choosing which crystal capacitance you use in a design.Note that this isnota question about choosing the capacitors--that I can do. Rather, I'm working on a design with an MSP430. The MSP430 has user-selectable load capacitance for the attached crystal, and can work with 1, 6, 10, and 12.5 pF crystals without requiring any external capacitors. 6 pF is, apparently, the default.Is there a reason I would choose one type over the other, aside from what I have on hand? Doing a design from scratch, is there a benefit to one over the other? Judging by the formula for the load capacitors, my intuition says that the larger the required load capacitance the better, because then the stray capacitance (and any variations in it) is less significant. Does that sound right, or are there other reasons that would imply lower capacitances are better to use, if possible?

author: tecman
author_rank: Frequent Contributor
timestamp: March 18, 2017, 10:42:28 pm
content: Higher crystal capacitance can increase the drive requirements, but will be less sensitive to stray capacitance.paul
Choosing copper wire thickness - Page 1
Forum section: electronics / projects

author: whatty
author_rank: Contributor
timestamp: March 13, 2023, 05:08:42 am
content: Hi,I had designed a fly-back transformer now i need to wind it on winding i need to choose the wire gauge thickness. Can any one help me to choose the correct gauge or direct me.i will provide data some necessary dataoperating frequency : 65KHziP peak :1.08 AiS peak: 9.23 AIp rms : 0.423 AiS rms : 3.84 ACore : ee 25/13/7Np : 71 turnsNS : 8 turnsNd : 10 turns

author: jonpaul
author_rank: Super Contributor
timestamp: March 13, 2023, 11:50:39 am
content: What is the Vp-s eg mains?What insulation required?EMI/safety compliance?Use wire tables, and Magnetics Designer if you have it.See websites of litz mfg like MWS and Rubidoux for HF /skin/prox effect tables and charts..Jon

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: March 13, 2023, 03:13:56 pm
content: Use the AWG table.The primary is wire No 25. The secondary must be Litz wire or multiple No 25.

author: jonpaul
author_rank: Super Contributor
timestamp: March 13, 2023, 06:24:44 pm
content: The wire tables are not specific (usually!) for HF use/skin effect nor transformers with Trise, hotspots.see excellent app notes and tables from MWS, Belden wire, etc.Jon

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: March 13, 2023, 07:19:26 pm
content: It is specific with skin effect. No25 is suitable up to 85khz, says the table. For the secondary....?

author: whatty
author_rank: Contributor
timestamp: March 14, 2023, 06:53:14 am
content: Hi do i need to choose wire thickness and number of wires needed in parallel based on rms current rating or peak current rating.Yes gauge 25 is rated for 85KHz thus it can be used for the primary my concern is when it comes to wire thickness do i need to consider rms current or peak current please tell me apart from the skin effect.

author: jonpaul
author_rank: Super Contributor
timestamp: March 14, 2023, 10:40:59 am
content: https://mwswire.com/litz-wire-tool/https://mwswire.comhttps://www.rubadue.com/https://www.rubadue.com/our-wires/litz-wires/
Choosing fan connectors for a prototype project - Page 1
Forum section: electronics / projects

author: Phoxtane
author_rank: Regular Contributor
timestamp: November 07, 2017, 04:19:46 pm
content: I'm currently working on my senior design project for college - a sort of capstone project for the four years of work I've put in so far. I'm currently picking out parts so I can get an order list to our department's parts guy, and I'm stuck on choosing fans. I don't need anything fancy, just your typical 12VDC fan that costs a buck or three.However, I'm stuck on the connectors; from what I can tell, Digikey and Mouser like to sell these kind of fans with bare wire leads. However, the fans inside my computer and on my 3D printer have these little JST-type connectors, similar/identical to the ones below:Since this is a prototype, and not a production-ready device, would it be acceptable to substitute in some screw terminals instead of JST-type connectors? This would allow me to avoid having to crimp the JST pins onto the fan's leads, and thus avoid having to buy a crimp tool, which I presume my department doesn't have. It also simplifies my BOM, as I don't need to purchase the male and female connectors + crimp pins, but just a single set of screw terminals (like the ones below).I believe if I was getting this widget assembled properly in some factory, I'd supply the fans and connectors and they'd put the crimps and other bits on as per the design - but that's really not feasible for a one-off prototype where I need exactly two fans hooked up!

author: Gribo
author_rank: Frequent Contributor
timestamp: November 07, 2017, 04:25:15 pm
content: Make sure you choose the correct pitch for both variants. Desktop PC Fan connectors are usually 2.54mm pitch, 4 positions, with some more compact designs using 2mm pitch connectors. 2.54mm screw terminals can be found easily, while 2mm terminals are less common.
Choosing Fast Ethernet PHY - Page 1
Forum section: electronics / projects

author: nuclearcat
author_rank: Unknown
timestamp: June 07, 2020, 09:16:17 am
content: Choosing PHY for my esp32 ethernet project. Seems most common are IP101GR (EspressifSystem devkit using it) and LAN8710 (Olimex used it) and price/availability is about same. It seems LAN8710 has weak side - can't send CLK to ESP32 MAC.ESP32 can operate only in RMII mode.Any other common PHY that can be used for this job?Any pifalls for young players? (except max 150ps skew)
Choosing filter capacitors [DC motor controller] - Page 1
Forum section: electronics / projects

author: XaviPacheco
author_rank: Regular Contributor
timestamp: July 20, 2018, 03:24:06 am
content: Hi,I'm designing a DC motor controller for treadmill. As stated in one of my previous posts, the motor is a PMDC with the following nameplate:LEESON Direct Current Permanent Magnet MotorMODEL: C4D48DB1AVOLTS: 125RPM: 5000AMPS: 27H.P.: 4.0DUTY: CONTAs it's for treadmill, the max power is rarely reached. I will rectify mains and use PWM technique with a power mosfet.Someone once suggested me not to use capacitors and just use the unfiltered voltage. But at the end of the day, I will get away with use them. I have seen many treadmills DC motor controllers, and some models use only one capacitor 1500uF @200V and other models use two 1500uF @200V capacitors in parallel.Well, doing de calculations with the formula Ic = Cdv/dt, using those capacitors value allow certain amount of ripple.Basically my question is:As I have decided to go with filtering the mains, what do you suggest? Using one capacitor (which saves space and cost) or two capacitors in parallel. Let's say the calculations throw a value around 3000 uF, why not to use one 3300 uF capacitor instead of two 1500uF? Is there any advantage on paralleling two capacitors with the same characteristics?

author: timpattinson
author_rank: Contributor
timestamp: July 20, 2018, 03:46:58 am
content: ESR/ESL?Also can be easier to package two smaller cylinders vs. one big one.Sent from my SM-G930F using Tapatalk
Choosing IGBT module for 230V/10A inverter output - Page 1
Forum section: electronics / projects

author: Miyuki
author_rank: Frequent Contributor
timestamp: December 31, 2018, 11:44:29 am
content: Hi folks,happy new yearIm looking for best option for power inverter with output: 230V 10A 50Hz sineInterestingly there is no suitable size H bridge modules on market which I need for chosen topologyBut ST have very reasonable priced SLLIMM™ family which is targeted as motor drives but for their price with integrated gate drivers look like good optionSomething like STGIB30M60TS-L is for better price than discrete solutionIs here any better alternative ?
Choosing IGBTs for a project - Page 1
Forum section: electronics / projects

author: haxby
author_rank: Contributor
timestamp: July 22, 2020, 04:18:04 am
content: Hi all,The short question:I need an IGBT that is in a TO247 package where the mounting tab is insulated electrically. Switching current around 50A or more, and voltage around 500 or more.....Is there such a beast?The long questions:So that I don't have to bug forums for questions like this in future, what tools do you use where you can do a parametric search of various suppliers of mosfets and igbt's...... Or do you just have to spend a lot of time sifting through hundreds of datasheets before you make a decision?

author: Hydron
author_rank: Super Contributor
timestamp: July 22, 2020, 08:24:28 am
content: Jump on digikey if you want parametric search and a wide enough range of stocked parts to make it useful (and a website that is nice and responsive, vs one that looks all fancy but sucks to use). As blueskull said, sounds like your best bet is IXYS (for isolated TO-247 as well as TO-264).

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 22, 2020, 04:32:51 pm
content: Quote from: haxby on July 22, 2020, 04:18:04 amI want to warn (maybe you don't need it): F-type case usually has much worse thermal conductivity. (I am talking about TO220F, but it possibly the same for TO247F). So it is much better to use thermal-conductive ceramics with heavy-loaded transistors.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 23, 2020, 12:28:43 am
content: Certainly not very many. What for?Insulators are cheap and plentiful. You may have trouble reaching full rated current, due to power dissipation -- insulators aren't the greatest thermal conductors (unless you happen upon some AlN plates, or hardcoat anodized aluminum isn't bad either). Not to mention frequency, which is unstated.These problems exist for any insulator, anyway, so you will find for example the "full-pack" (fully encapsulated) types have much lower DC current or power limits for the same reason a tabbed device with external insulation has reduced limits.The best of course are ceramic (often AlN or relatives), direct bonded, but yeah, you'll have to shop around, and you'll find a limited selection.Tim
Choosing inductor for switching buck IC (wide output range) - Page 1
Forum section: electronics / projects

author: MarkusAnd
author_rank: Contributor
timestamp: October 20, 2021, 06:12:10 pm
content: Hi!I want to use a LM2576-switcher to output a voltage between 3-17V at max 1.5A from a 18V input. Can I use just one inductor for this range, or do I need to switch between two different values depending on what output-voltage I want? If I am able to use just one, for what output voltage should I calculate the inductor value?Markus
Choosing inductors for your application - Page 1
Forum section: electronics / projects

author: R_G_B_
author_rank: Frequent Contributor
timestamp: November 21, 2021, 09:16:37 pm
content: I want to design a narrow bandpass filter say 10% of the centre frequency of 100khz.Problem is that when designing such a filter using passive components. The inductors are quite large at these frequency. Wire wound seem best suited for these frequency however they are quite large. Ferrite multilayer inductors such as SMD type don't have the required quality factor. Also if I could find a inductor with a self resonate frequency close to the required centre frequency and use that as it would offer a high quality factor. I would like a high q inductor that has a smallest possible footprint suitable for the centre frequency 100khz as mentioned above any help will be appreciated. Thanks I found the Following link which is useful to others on this forum as mentioned in the link it difficult to find small inductors for this frequency range.https://www.ednasia.com/passive-filter-design-made-easy/

author: Benta
author_rank: Super Contributor
timestamp: November 21, 2021, 09:32:43 pm
content: Quote from: R_G_B_ on November 21, 2021, 09:16:37 pmWhat does that mean? -6 dB? -12 dB? -100 db?100 kHz is not difficult and absolutely doable for passive LC filters. But at which impedance?The link you posted uses immense inductor values and miniscule capacitors. It's totally off, somehow.Please be specific about what you need.

author: PartialDischarge
author_rank: Super Contributor
timestamp: November 21, 2021, 09:36:38 pm
content: I would try to do it active, if passive is the only way use this linkhttps://rf-tools.com/lc-filter/

author: tszaboo
author_rank: Super Contributor
timestamp: November 21, 2021, 09:38:22 pm
content: How much power (if any) do you want to pass through this filter?

author: R_G_B_
author_rank: Frequent Contributor
timestamp: November 21, 2021, 10:56:30 pm
content: 20k input impedance Low power say 100u watts. Roll off factor 60db per decade40db would be ok. 3db 10% of the centre frequency. I need a narrow filter to help increase the signal to noise ratio. In order to Increase a signals detectability. Small foot print PCB required. So I wanted smallest Inductors as possible.To for on the board of 45mm X 25mm.

author: jonpaul
author_rank: Super Contributor
timestamp: November 22, 2021, 08:33:25 am
content: RGB: A great topic, but the EDN Asia article is not a fine reference.Suggest to study filter design and theory, many classic books and sites describe the specification and design of filters.You can get commercially made BP filters eg from Mini-Circuits, they may have a 100 kHz BP, probably Zo 50 Ohm.Bon ChanceJon

author: tszaboo
author_rank: Super Contributor
timestamp: November 22, 2021, 11:18:02 pm
content: Quote from: R_G_B_ on November 21, 2021, 10:56:30 pmYou are much more likely in need of a common mode choke. See if you can place that into your circuit.Try to avoid the X-Y problem, explain what you are trying to do.
Choosing IR Illuminator LED for LIDAR design - Page 1
Forum section: electronics / projects

author: AndrewLoomis
author_rank: Contributor
timestamp: May 31, 2018, 06:22:41 pm
content: I'm making a LIDAR time of flight sensor, and recently discovered TI's new chip: OPT3101.http://www.ti.com/product/OPT3101/technicaldocumentsThis chip isn't even in production yet, but very cool. Pretty much just add your own LED and photodiode, and you're set. The OPT3101 allows you to have 3 independent illuminators that are multiplexed, so I am looking to have 3 separate 20-30 deg FOV LED's to get a range finding FOV of 70-90 deg. The problem is that I have found no resources to calculate max range given the FOV of LED, radiant intensity, and illumination power. I've looked through the datasheet:http://www.ti.com/lit/ds/symlink/opt3101.pdfand the app note:http://www.ti.com/lit/an/sbau305/sbau305.pdfwithout being able to find an equation or estimate for max range. I'm new to optics/time-of-flight so I may be missing something. This is the LED I'm currently looking at using:https://www.digikey.com/product-detail/en/osram-opto-semiconductors-inc/SFH-4655-Z/475-1260-1-ND/1468205

author: _Wim_
author_rank: Super Contributor
timestamp: June 02, 2018, 06:43:31 am
content: Hi, thanks for pointing us to this interesting new chip.From glancing through the datasheet, it seems that the calculations you need are explained in detail in 8.2.2.4. First you calculate the noise current with the chosen sample rate, photodiode capacitance and ambient current (see chapter before to calculate ambient current). This noise current defines your maximum range and resolution (at max range this is the minimum current you will still receive from the photo diode).Below are the formulas to calculate the required optical power from the light source (led or laser). Once this is calculated, you can then calculate the minimum detectable distance below (when the device saturates because of too much light).

author: AndrewLoomis
author_rank: Contributor
timestamp: June 02, 2018, 11:43:27 am
content: Thanks for the reply, I ended up figuring it out, and even found an error in the datasheet that I reported to TI. One of the first equations had a misnamed variable that through me off. After I read a lot more into how lidar and time of flight works, the equations made sense. Thanks again for confirming though, I'm excited to start working with this chip!
Choosing mosfet for reverse bias protection - Page 1
Forum section: electronics / projects

author: alexg
author_rank: Regular Contributor
timestamp: July 22, 2017, 07:33:45 pm
content: Hi all, I have a quick question, I need to make reverse bias protection for 4 AA batteries block, I currently tried this one and it works well:https://www.fairchildsemi.com/datasheets/FR/FR014H5JZ.pdfhowever, isn't it the same thin as P-channel mosfet? I am asking because if it is, then I can find P-channel mosfet on digikey that is a bit smaller and has less Rds resistance.

author: hermit
author_rank: Frequent Contributor
timestamp: July 23, 2017, 12:55:18 am
content: It can be done with a P Channel MOSFET. Just do a google search.

author: hermit
author_rank: Frequent Contributor
timestamp: July 23, 2017, 04:15:44 am
content: Well, taking time to figure out the thermal resistance and power dissipation for 1 oz copper since that device is speced at 2 oz copper with a 1 inch square thermal pad, I'm not sure how much engineering time you save. And the example is a USB connection? Lower Rds might start looking better. Again, just choices I suppose.
Choosing Package Size - Page 1
Forum section: electronics / projects

author: law_freak
author_rank: Contributor
timestamp: February 07, 2017, 10:17:16 pm
content: In my particular situation, I am choosing between the following two SMD 5-volt LDO regulators in TO-252 and TO-263. No mention is made in the datasheet about the superiority of either package for any particular purpose. Besides size, what is the conventional wisdom for choosing a larger or smaller package.When given two identical components in varying package sizes, is the larger package likely to be thermally superior?LD1086 5-volt LDO regulator in TO-252-3LD1086 5-volt LDO regulator in TO-263-3

author: mmagin
author_rank: Frequent Contributor
timestamp: February 07, 2017, 10:19:09 pm
content: mostly you're choosing physical size and thermal characteristics.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: February 08, 2017, 04:01:15 am
content: Generally, a larger package carries a bigger load...

author: mmagin
author_rank: Frequent Contributor
timestamp: February 08, 2017, 04:56:48 am
content: To expand on the comment I made earlier:One of these is 3 °C/W junction to case thermal resistance, the other is 8 °C/W. If you're dissipating 10 watts, that's the difference between comfortable operation and "hope you don't expect to ever use this in hot weather".

author: DaJMasta
author_rank: Super Contributor
timestamp: February 08, 2017, 06:23:37 am
content: That's really the only good reason in most cases. Even if there's not a big thermal pad, you get some more thermal capacity and some extra surface area for heat radiation, but the larger package means a MUCH larger metal heat transmission pad, and probably a better thermal junction from the die to the pad, which gives you much more efficient heat dissipation.If you don't need to dissipate the heat, the smaller size is probably plenty and you save on board real estate. On some rare devices, maybe there could be advantages of a large package for high voltage insulation.... but generally devices rated to that kind of voltage simply don't come in smaller packages where it could be an issue.

author: grifftech
author_rank: Frequent Contributor
timestamp: February 08, 2017, 03:56:27 pm
content: How do you plan to solder them?

author: DBecker
author_rank: Frequent Contributor
timestamp: February 08, 2017, 05:23:25 pm
content: You've heard it before: The size of the package matters less than how it's used.There are some pretty amazing thermal solutions in tiny packages. It's easy to overlook that the point of a package isn't to get rid of heat. We no longer use TO92 parts standing tall, like a water tower in the wind. The package transfers the heat from the point of generation to the copper of the circuit board. A smaller, thinner package with a shorter path from the die to the board can do pretty well compared to a bigger package. Compare a SOT23 to that old TO92. Compare a DIP to the same part in a SSOP. And since the same amount of heat goes into the circuit board in either case, 'good enough' is the pretty much the same 'not using all of awesome'.
Choosing right inductor... - Page 1
Forum section: electronics / projects

author: 3dgeo
author_rank: Frequent Contributor
timestamp: January 14, 2019, 09:46:30 am
content: Hello,I'm making step down converter (based on "Great scotts" BMS, schematic below) for LiPo battery to replace 2 AAA batteries and my knowledge about inductors is a bit weak, so I need help.MT3420 data sheet recommends 1-4.7uH with low DCR for higher efficiency, lowest DCR I managed to find is 4.2 mOhms@2.2uH(13x13x7 mm), but also I found 24mOhms@4.7uH(8x8x4mm). How much of an impact inductor inductance and DCR has in this particular case, load will be wireless mouse (will make separate thread on it in a few min...).Thanks in advance.(don't mind resistors values)

author: mvs
author_rank: Frequent Contributor
timestamp: January 14, 2019, 10:40:30 am
content: Quote from: 3dgeo on January 14, 2019, 09:46:30 amPower loss due DCR is P=I²R. If your mouse consumes 50mA, then it is 2.6µW vs 15µW.

author: 3dgeo
author_rank: Frequent Contributor
timestamp: January 14, 2019, 11:11:51 am
content: Quote from: mvs on January 14, 2019, 10:40:30 amThank you.Does inductance have a huge impact on this small load? Cos that inductor is 13x13x8mm, would like something smaller if it's possible

author: mvs
author_rank: Frequent Contributor
timestamp: January 14, 2019, 02:21:50 pm
content: Quote from: 3dgeo on January 14, 2019, 11:11:51 amWith lower inductance this converter may stay a bit longer in PFM mode, but I do not think that you get a huge power savings from it.For light load scenario i usually tend to choose higher inductor values (so 4.7uH or perhaps even more) to get better regulation and lower ripple current.
Choosing smoothing caps - Page 1
Forum section: electronics / projects

author: Distinctly Average
author_rank: Contributor
timestamp: January 17, 2021, 09:18:48 pm
content: I have begun building on the orders of my daughter some esp2866 WS2811/12 based LED displays in readiness for next Xmas. She wants to do the whole X-Lights thing and It seems to work really well with these cheap little boards. I’ve built three panels and a tree and am using a PI zero to run falcon player software to control them all. The power feeds are coming from separate PSUs and the recommendation is to slap a cap across the input to each as spikes can kill the first LED in a string. So the question is, how does one decide on the value of such a cap? Is there a calculation to use?

author: Siwastaja
author_rank: Super Contributor
timestamp: January 18, 2021, 08:02:05 am
content: Actually calculating the optimum power distribution network for such hard-to-describe ad-hoc system becomes quite complex. But this isn't needed.I really recommend electrolytic caps for such "no-analysis", "after some wiring" extra capacitors. Their high ESR makes it nearly impossible for them to make inrush voltage peaksworse, they are good for damping parasitic LC oscillations.On the other hand, if you slap a 10uF MLCC (ceramic capacitor) there, it will likely cause serious overvoltage peaks.In such cases where there are no high ripple currents present, almost any value of electrolytic works! Because the circuit doens't cause large ripple currents to flow through the capacitor, the capacitor will last long even if it is "too small". You can always verify this by touching the capacitor; it shouldn't heat up basically at all.Obviously, pick one with at least, or a bit more voltage rating than the maximum possible voltage it will ever see in that line.Note that with too much capacitance, whatever supplies the power may have hard time initially charging the capacitors, possibly entering some short circuit / protection mode. For example, USB spec limits maximum device power capacitance to 10uF unless you provide inrush current limiting. Some 47uF electrolytic is very likely fine though because they have so much ESR to limit the current itself, also the 10uF spec is quite conservative IMHO. A stand-alone multi-ampere 5V power supply on the other hand likely handles thousands of uF just fine.

author: Ian.M
author_rank: Super Contributor
timestamp: January 18, 2021, 08:30:41 am
content: https://learn.adafruit.com/adafruit-neopixel-uberguide/best-practicesAdditionally to the above link, connecting aBAT54Sdual series Schottky diode (or two small signal leaded Schottky diodes, e.g.BAT42, if you prefer to avoid SMD parts) at the input to the string, between the recommended data line series resistor and the first LED, to clamp the data line (i.e. cathode to 5V, common to Data, anode to Gnd) so it cant go outside the supply rails will make it *MUCH* harder for any transients to kill the first LED.

author: Distinctly Average
author_rank: Contributor
timestamp: January 18, 2021, 10:41:20 am
content: Thanks all. Here is so much to learn for me here.
Choosing the right controller for BLDC motor - Page 1
Forum section: electronics / projects

author: THORs_Hand
author_rank: Contributor
timestamp: February 14, 2020, 05:37:33 pm
content: Hello!I am currently working on a project that requires a motor to be driven at a very constant speed that can quickly react to changes in load and adjust accordingly.Naturally, i've turned to a BLDC motor, one in a NEMA enclosure that will also have an encoder attached to it.Now, i have to implement into the board directly a BLDC driver for this motor, but i am not sure what IC to use as i never designed boards with BLDC drivers on them, also i'd need it to be controlled via I2C or SPI since it would be simpler to code for as the controller for the driver will be a Atmega328P since i want to offload these tasks off my main processor.What would be your recommendation for such an application?
Choosing the right power supply for many fans. - Page 1
Forum section: electronics / projects

author: TimB100
author_rank: Contributor
timestamp: November 28, 2019, 07:13:35 am
content: Hello PeopleI'm building a product that drives 6 x 2.4 amps fans. Add in a another 1amp for leds and pumps etc your at 15.4amps at 12vThe big requirement is that its splash proof. When you search for those requirements you end up at LED drivers. I'm thinking say a Meanwell ELG-200-12-3Y at 16 amps or the hlg-240-12 or one like that.But then I got to thinking is a LED driver power supply right, will that cause issues? The Fans will be PWM driven for a short period as they ramp up speed. But after that it's just full power.Any thoughts?Thanks Tim
Choosing the right resistors for SWVR for output voltage(mp1584en) - Page 1
Forum section: electronics / projects

author: ReadyEdi
author_rank: Newbie
timestamp: October 23, 2017, 07:55:15 am
content: Hi everyone,So I need to design a 12V voltage regulator that takes up to 26V in the input and came across a dilema with choosing the resistors.When I use the referenced 40.2Kohm R2 resistors that is suggested in the datasheet and use it with the equation R1=50.25*(Vout-0.I get an R1 = 562.8KOhmWhich seems quite high which leads to another question why is not suggested to use high resistance values?Anyway in order to calculate another value for R2 you can use the equation from the datasheet below:and the question now is: What values does V-FB has? how do you find it?Thanks for helping.
Choosing transformer for quick psu - Page 1
Forum section: electronics / projects

author: Crispy24
author_rank: Newbie
timestamp: September 08, 2012, 12:24:18 am
content: Hello eevblog forums,I'm making a variable power supply for a first time, no special features, and I'm having trouble choosing a suitable transformer to step down from mains voltage to ~30Vac.I did some research and I found the Hammond 229D30I'm basically looking for a transformer capable of supplying minimum 20Vrms @ 1.0ArmsCould someone please give me some technical advice on a good, cost effective transformer that would do this?Thank you!

author: Rerouter
author_rank: Super Contributor
timestamp: September 08, 2012, 01:13:18 am
content: well you work on your VA rating, the one you chose has a rating of 48VA, so the 30V secondary is likely when your pulling 1.6A on the output, and it will float a little higher at lower loads, (good thing to know if your components are only 36V) as transformer ratings are usually what voltage its at when your pulling the rated wattage / VA,so if your only looking for 20V, you can get away with a 24V, 28VA rated transformer, and if you need higher current you chase a higher VA transformer, (generally get one rated atleast 2-3V above your ideal voltage for your bridge rectifier)
Choosing welding Dc Link Capacitor  - Page 1
Forum section: electronics / projects

author: ow19m
author_rank: Contributor
timestamp: April 07, 2022, 09:38:24 am
content: Hello ,These Rifa 3300uf 450v capacitors are very expensive , im trying to build a 250kva 650amp rated welding inverter .My question is , is it possible to provide the same ripple current with using (470uf 450v )X4 capacitors combination to make a 3300uf 1800v 650amp approx Dc Link capacitor bank ?

author: CaptDon
author_rank: Super Contributor
timestamp: April 07, 2022, 01:44:51 pm
content: Is the link voltage 1800vdc??? Where did that number come from? I don't understand your math. You want to create 3300uf@450v? You listed 470uf@450v times 4. In parallel that would be 1880uf@450v or in series it would be 117.5uf@1800v and based on the high expected ripple current putting these in series is a really bad idea unless you had some really large power wasting equalizing resistors to distribute the voltage equally across the series string. The capacitors in parallel giving 1880uf@450v is o.k. if that is where you are headed. Again, where did the 1800 volt number come from? We only use 1400 as the link voltage on our 4500hp 3.3MW locomotives.

author: CaptDon
author_rank: Super Contributor
timestamp: April 08, 2022, 01:03:16 pm
content: Bueller.......Bueller...... O.P., did you solve this issue? 250kva 650amp What are you welding? The Golden Gate Bridge?

author: jonpaul
author_rank: Super Contributor
timestamp: April 09, 2022, 08:57:46 am
content: 1800 V a typo? the 4 caps would be in parallel?Anyway the layout and construction is very poor for 250 KVA equipment.Is the OP REALLY qualified to work at such VERY DANGEROUS voltages and power levels?Jon

author: ow19m
author_rank: Contributor
timestamp: April 15, 2022, 08:45:53 am
content: Extremely sorry for the typos,as embarrassed as I am , Well you all got me I'm not building it rather curious about the calculation , I'm 19 by the way , Id think twice while even touching 400v. the four caps in the picture are basically series parallel combination of 3300uf 900v. @jonpaul you right im not qualified but can you point out why the construction is poor ? and can anyone tell me how to roughly calculate Dc link Capacitance. I'd suspect with this much voltage the design has to incorporate a Relay which is going to charge the capacitor once the welding turns on for the first time , and discharge as soon as the unit is turned off !
chopper amplifier phase (margin?) - Page 1
Forum section: electronics / projects

author: CopperCone
author_rank: Super Contributor
timestamp: January 04, 2018, 09:34:53 pm
content: I was looking at the LTC1150 and it just says gain/phase on a graph.Do they mean phase margin? I.e. only valid for open loop applications?If I understand, the phase margin is usually not relevant, as phase inversion usually is designed to occur past the 0dB gain point, and it will oscillate there, but it may be involved sooner if a heavy capacitor is used..http://cds.linear.com/docs/en/datasheet/1150fb.pdfand that means that the phase will be inverted or equal depending on the type of feedback used (inverting or non inverting).Not too familiar with chopper amplifiers though, thought I would check.

author: mikerj
author_rank: Super Contributor
timestamp: January 04, 2018, 11:25:28 pm
content: That's the open loop gain and phase with 100pF load on the output.

author: David Hess
author_rank: Super Contributor
timestamp: January 05, 2018, 01:06:21 am
content: Quote from: CopperCone on January 04, 2018, 09:34:53 pmTechnically it is not a chopper amplifier; it is a chopper stabilized amplifier which is a very different thing. In all respects, it may be treated as a linear operational amplifier with some special characteristics.The gain and phase graph represents the same thing as it would on a normal operational amplifier.
Chopper opamp supply noise? - Page 1
Forum section: electronics / projects

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 18, 2015, 05:25:05 am
content: I'm working on a HD DAC/headphone amplifier that uses a TPA6120A2 as the output amplifier. It has a few mV of offset which doesn't seem like much, but it's enough to make a very obvious click in the headphones when the output relay opens or closes.Therefore, I want to use a low offset opamp like a LTC1051 as a DC servo to null out that offset. But how much noise do chopper opamps introduce to their supply rails? Is it likely enough to degrade the SNR of the system? (I'm going for a system SNR of well over 110dB, with the actual DAC chip being specified for 127dB.)

author: Andreas
author_rank: Super Contributor
timestamp: July 18, 2015, 05:54:49 am
content: Hello,read datasheet page 6 above figure 1:I is more likely that you will have the noise directly at the input of the LTC1051.As charge injection from the clock to the input switches.With best regardsAndreas

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 18, 2015, 05:58:40 am
content: There's going to be plenty of filtering where the servo opamp interfaces into the output amplifier. I just want to know how much filtering (if any) I should put on the supply rails.

author: SeanB
author_rank: Super Contributor
timestamp: July 18, 2015, 07:08:22 am
content: Your power driver should have enough PSRR to handle it, and the DC correction servo should have standard opamp decoupling on it's rails in any case, so the usual 100n ceramic and 10uF electrolytics from each rail to ground should work well enough to do it, probably there in the datasheet or app notes as part of the demo circuits.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 18, 2015, 07:30:08 am
content: Noise would be more a problem through the input. A better choise would be a normal low Offset OP (e.g. LT1013) for the DC controll.Normally a manual adjstment of the DC offset of the existing amplifier schould be enough, to keep below 0.1 mV.

author: sarepairman2
author_rank: Frequent Contributor
timestamp: July 18, 2015, 07:42:25 am
content: im gonna do some serious experiments on this when I finally get a DSA that works

author: dom0
author_rank: Super Contributor
timestamp: July 18, 2015, 05:01:11 pm
content: A normal precision OP easily suffices for this. Depending on the headphone impedance the audible offset varies and is especially low with high-efficiency 32 ? or 16 ? headphones. Better studio phones are much less sensitive and the acceptable offset is much higher.With <1 mV of offset you should be on the safe side with almost any headphone.