hybridfree/eevblog-posts huggingface dataset:
Cable storage/organization - Page 1
Forum section: electronics / beginners

author: int2str
author_rank: Regular Contributor
timestamp: October 05, 2015, 04:45:29 am
content: Beginners forum, since well, starting out....As I'm starting to collect gear (DMMs, scope, generator etc), I'm amassing cables in the process. Probes, BNC, hookup leads, USB cables, etc. How does one keep their bench organized, yet the cables semi-handy?I don't need most of the cables most of the time, but of course I don't want to have to dig for them when I need them.Tips tricks?

author: rdl
author_rank: Super Contributor
timestamp: October 05, 2015, 05:33:50 am
content: I bought a plastic peg board kit last year for my little lab in a closet. It's not the most efficient use of the peg board space though. If I ever need the room for more tools I'll probably have find something better for the cables.

author: ketil b
author_rank: Regular Contributor
timestamp: October 05, 2015, 06:06:33 am
content: HiElement14 had a deal onPomona cable racksso I picked up two.thanksketil

author: tooki
author_rank: Super Contributor
timestamp: October 05, 2015, 10:51:52 am
content: I'm running into the same problem. However, hanging up cables simply isn't an option, I do not have the wall space for it. Anyone got any clever suggestions? (I'm just using little drawers and ziploc bags at the moment.)

author: jeroen79
author_rank: Frequent Contributor
timestamp: October 05, 2015, 03:17:05 pm
content: You could put the racks on a rail and perpendicular to the wall.then you can put a bunch of them together and slide out the rack you need a cable from.

author: tggzzz
author_rank: Super Contributor
timestamp: October 05, 2015, 04:19:29 pm
content: Quote from: tooki on October 05, 2015, 10:51:52 amDepending on geometry, maybe the space behind a door or on the back of a door?
Cable strippers with a single blade - Page 1
Forum section: electronics / beginners

author: fabiodl
author_rank: Frequent Contributor
timestamp: January 17, 2022, 09:44:10 am
content: I have a cable stripper for coax cables,specificallythiswhich has 3 blades.It has three blades. Many times I need to strip multiwire cables other than coax, for instancethisAre there single blade tools? I do not want to remove the blades from the one I have, I'd like to keep as it is for actual coax cables.

author: nali
author_rank: Frequent Contributor
timestamp: January 17, 2022, 10:02:09 am
content: Try a Google (images) search for "mini UTP stripper", that'll probably throw up something suitable.

author: jpanhalt
author_rank: Super Contributor
timestamp: January 17, 2022, 10:02:35 am
content: There are wire strippers like this: <attachment 1>They can do multiple wires, but may not be wide enough for your needs.For ribbon cable, I just use a spring clip and hot air gun <attachment 2>. I believe there are commercial units available but don't have a link handy. If I were only doing a few (as is my case), I use the spring clip. Insert the wire, heat with hot air until it is hot enough, then pull. Hot enough is based on vision, timing, a little practice, and smell if PVC.

author: fabiodl
author_rank: Frequent Contributor
timestamp: January 22, 2022, 10:27:11 am
content: Quote from: nali on January 17, 2022, 10:02:09 amThank you, this is exactly what I was looking for!Quote from: jpanhalt on January 17, 2022, 10:02:35 amNice Idea for the ribbon cables,I'll try next time I need to!
Cable to power multiple devices from a power bank - Page 1
Forum section: electronics / beginners

author: JRL
author_rank: Newbie
timestamp: November 30, 2016, 08:07:03 pm
content: Hi allFirstly, I hope this is an appropriate question for the forum, I'm a newbie so not sure if this sort of thing is covered. If not appologies.I'm a location sound mixer some of the time and want to stop using up batteries so am looking at rechargeable options. One of them is a power bank.I want to power a portable audio device (Zoom F4) and a radio mic receiver. The recorder has a hirose connector (product info says HIROSE HR10A-7R-4S 4-pin connector (1 pin: ?, 4 pin: +), 9–16 V) and so I think it requires 12VDC. The Lectrosonics radio mic receiver requires a 6-18VDC 150mA - 75Ma. I was hoping to get a Y splitter cable made up that goes from the one Power Bank source to the 2 separate VDC inputs.I don't want to know how to do this, as if it can be done I'll get an expert to make it for me as I'm not the best at soldering, I'd just like to know if it can be done. Is this possible?Also any advice on what minimum specs that the power bank should have would be appreciated? I'm assuming that I the bigger the mAh rating just means it'll last longer?Any advice appreciated.CheersJason

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: December 01, 2016, 04:09:49 pm
content: I guess that the best thing you could get would be one of those powerbanks which allow you to switch to different output voltages. Otherwise you could consider taking a standard powerbank and attach a switchmode power supply, i.e. a step up boost converter, to its output and controll it so that it outputs 12V, and attach some wires to it that connect to your devices.This can be done by nearly everyone who knows which side of the soldering iron gets hot

author: JRL
author_rank: Newbie
timestamp: December 01, 2016, 10:50:01 pm
content: Danke. I'll do some more research and watch my fingers while soldering!

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: December 02, 2016, 08:38:07 am
content: if you have any questions or if my post wasn't clear, please feel free to askhave fun with your Project!
Cables and Attenuators  - Page 1
Forum section: electronics / beginners

author: Ranger14
author_rank: Regular Contributor
timestamp: May 27, 2016, 03:51:02 pm
content: I am looking to get some bnc patch cables for use on my scope,funtion gen,and counter .. But does it matter if you buy chinese cables or try to purchase qualityAlso I was looking to make some attenuators and how hard would these be to make and can they be use to make measurement ?? I was interested in 2x,5x,10, attenuators..Are the bnc connectors male and female out of china any good to use in taking measurement and cal

author: TimFox
author_rank: Super Contributor
timestamp: May 29, 2016, 02:00:26 pm
content: The connections on quality cable assemblies are more reliable than on cheap ones -- almost a law of nature.If you are not using high frequencies, you don't need to worry (much) about mismatch, etc., but intermittent connections are horrible when testing things.When making your own attenuators, etc., try to keep the assembly short -- much, much shorter than the shortest wavelength you intend to use. For audio, that means that a normal aluminum project box with BNC connectors should work without trouble.

author: German_EE
author_rank: Super Contributor
timestamp: May 30, 2016, 04:32:16 pm
content: 1) Quality will last longer, you only have to buy a good tool once.2) Quality cables will leak less. This may not be important with a 10dB attenuator but when you are aiming for 60dB attenuation you will find that the amount of leakage from your sockets and cables is a measurable amount.3) Quality cables will have a constant impedance from end to end including the connector, this is important for some RF measurements as a poor quality cable could be a source of error.Most of my RF measurements are done with cable of reasonable quality but for some low-level tests such as MDS (Minimum Discernible Signal) I have two Minicircuits cables. These are DC to 18 GHz (although I never work that high), triple shielded, have less than 1dB loss from end to end and were sixty Euro each. I suspect that they will never fail.

author: karoru
author_rank: Regular Contributor
timestamp: May 30, 2016, 05:45:32 pm
content: Quote from: Ranger14 on May 27, 2016, 03:51:02 pmBuy some Chinese cheapies anyway, they don't cost much and you never know when you need that additional piece of coax for connecting some random non-critical test setup. And ask around some IT LAN people, they'll probably have boxes and drawers full of 50 Ohm ethernet coax, terminators & BNC T adapters that just lie around collecting dust and waiting for nuclear winter.

author: Ranger14
author_rank: Regular Contributor
timestamp: June 01, 2016, 04:20:10 pm
content: Thanks for the great infoI forgot to ask when building your own cables for scope function gens do you use RG-174 or RG-58 and why ??Thanks

author: onesixright
author_rank: Frequent Contributor
timestamp: June 21, 2016, 07:46:40 pm
content: I would use RG58. The main difference is that the attenuation is less for RG58, especially on higher frequencies.
Cadence or Synopsys EDA training - Page 1
Forum section: electronics / beginners

author: steamedhams
author_rank: Regular Contributor
timestamp: July 24, 2021, 03:10:35 pm
content: As an individual, how can I learn these tools that these companies offer without playing through the nose.I cannot find a cracked version and they dont seem to offer free software to learn.Do i just have to find a junior position??

author: ebclr
author_rank: Super Contributor
timestamp: July 26, 2021, 08:43:24 am
content: If they didn't give you free software just pay it or don't use it, Otherwise look on Chinese forums because they don't respect anybody's intellectual property

author: emece67
author_rank: Frequent Contributor
timestamp: July 26, 2021, 09:55:15 am
content: .

author: PKTKS
author_rank: Super Contributor
timestamp: July 26, 2021, 10:30:21 am
content: Quote from: emece67 on July 26, 2021, 09:55:15 amYES that is (at least was..) TRUE...Serious academia invests in such platforms and while having access to them is a very good option to learn a great deal on expensive "licensed" tools..BUT!!! Way before Cadence took over control of OrCAD the folks already were smart enough to properly support a wide broad of users, so even not having academia access one could still ask for such products.I did that sometimes and I was very good served with ready CDs.. (attached)But once the MS digital landlord realm became a total unbearable nuisance and I switched entirely to *NIX at time.. Eagle and KiCAD and SPICE filled the gap perfectly.May be the Cadence folks are still smart enough to:- get rid of MS realm..- provide wide broad users support as they were used toPaul
Caig DeoxIT on oscilloscope BNC connectors? - Page 1
Forum section: electronics / beginners

author: dave3533
author_rank: Contributor
timestamp: October 03, 2014, 05:24:00 pm
content: Hey all, I've seen quite a few mentions of using DeoxIT on switch contacts and the like but never oscilloscope BNC connectors. Is DeoxIT safe for oscilloscope BNC connectors as far as not interfering with the input signal? I'd imagine, if anything, it could somehow change the impedance of the connector.

author: edavid
author_rank: Super Contributor
timestamp: October 03, 2014, 05:43:17 pm
content: Quote from: dave3533 on October 03, 2014, 05:24:00 pmYou don't read about it because it is rarely necessary to use contact cleaner on BNCs. When you mate the connector, it has a strong wiping action.But, if you did need to clean one, DeoxIt would be fine.Impedance is determined by connector geometry, not an insignificant residue of contact cleaner.(BTW, if you see a tarnished BNC, you can leave it alone... silver tarnish is conductive enough not to be a problem. However, you won't see silver plated BNCs on test equipment.)

author: dave3533
author_rank: Contributor
timestamp: October 03, 2014, 09:37:09 pm
content: Great, thank you for the reply edavid.I was considering using DeoxIT shield or gold as a preventative measure, but it sounds like it might not be worth it anyway.

author: robrenz
author_rank: Super Contributor
timestamp: October 03, 2014, 09:53:24 pm
content: Quote from: dave3533 on October 03, 2014, 09:37:09 pmI think the gold is worthwhile, it goes on every connector/plug in my lab.

author: rs20
author_rank: Super Contributor
timestamp: October 04, 2014, 12:58:12 am
content: If I have a nice shiny oscilloscope connector, and the only feedthru terminations I have look all tarnished and dull, can I be confident that the tarnish won't spread from the termination to the connector?

author: edavid
author_rank: Super Contributor
timestamp: October 04, 2014, 06:04:54 pm
content: Quote from: rs20 on October 04, 2014, 12:58:12 amTarnish is a chemical reaction, not a disease.
Caig deoxIT to clean the rotary switch - Page 1
Forum section: electronics / beginners

author: nadona
author_rank: Regular Contributor
timestamp: December 24, 2012, 06:39:52 am
content: Which one to buy from these Caig de-oxit?http://www.amazon.com/s?ie=UTF8&field-keywords=Caig%20de-oxit&index=blended&link_code=qs&sourceid=Mozilla-search&tag=mozilla-20

author: saturation
author_rank: Super Contributor
timestamp: December 24, 2012, 02:54:00 pm
content: If you've never used it, get the sampler, the stuff is very effective that tiny drops are all you needhttps://www.eevblog.com/forum/beginners/to-fix-or-buy-a-new-scope/msg120451/#msg120451http://www.amazon.com/Squeeze-Tube-Kit-Essentials-samples/dp/B0018KNHRY/ref=sr_1_24?ie=UTF8&qid=1356358514&sr=8-24&keywords=deoxitDetails on what each is for is on the Caig website.

author: nadona
author_rank: Regular Contributor
timestamp: December 24, 2012, 11:21:32 pm
content: @saturation;thank you. This deoxIT is for TW5000W. Even though it is very stable in terms of voltage change, it is hard to adjust at uV range.Thank you again for all the suggestion implied or explicit
Calculate battery consumption, to know battery remaining - Page 1
Forum section: electronics / beginners

author: paul_allsopp
author_rank: Newbie
timestamp: January 23, 2017, 04:38:25 pm
content: Hey all.I've designed a project with an ESP8266 at it's heart, which I would like to drive from a Li-ion battery. So I have two questions about this:1. What's the best practice approach to measure the current consumption of the project?2. How do I add an LED bar to show the remaining charge in the battery, with the purpose of knowing when to recharge it?Thanks for any info on this.Paul

author: suicidaleggroll
author_rank: Super Contributor
timestamp: January 23, 2017, 05:13:06 pm
content: The simplest is to measure the battery voltage and create a lookup table relating voltage with charge level. I believe this is what most cheaper devices use, and it works reasonably well as long as you're not dealing with large discharge currents. The readings will be skewed while charging though.The more accurate way is to use a voltage and current monitor to measure and accumulate the total energy consumed from the battery. It might take a couple of charge/discharge cycles to "teach" it the battery capacity this way.

author: paul_allsopp
author_rank: Newbie
timestamp: January 23, 2017, 05:42:53 pm
content: So, something like this:https://www.sparkfun.com/datasheets/BreakoutBoards/0712.pdf?

author: suicidaleggroll
author_rank: Super Contributor
timestamp: January 23, 2017, 06:25:30 pm
content: That's just a current sensor, there are hundreds of current sensors you could use if you wanted to do it yourself. You could also use a self-contained "fuel gauge" to do it for you, eg LTC2942http://www.digikey.com/products/en/integrated-circuits-ics/pmic-battery-management/713?k=fuel%20gauge
Calculate Cable thickness depending upon current  - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: March 28, 2017, 04:58:31 am
content: 1. I have bought a low cost ac-dc charger from China. It is from 220Vac/50Hz to 54.6Vdc/20V charger.It dont have any manual or wiring diagram with it. It has five connections: Line,Netrual & earth on input. On output it has thick terminals for V+ & Ground.2. At output 54.6Vdc/20A, wattage is 1092W. How to calculate what is the exact wire & its size I should use. I have to charge a battery, so have to make red & black wire with clips myself. But what wire size(AWG) should I buy.3. Similarly at input, it is 220Vac/50hz. Output is 1092W, consider charger is 75% efficient (though there is no manual, I am cosindering this as worst case), power at input will be: 1092W/0.75 = 1456W.For this which wire should I use?Is there any calculator to calculate?1. For dc, I found below:http://www.solar-wind.co.uk/cable-sizing-DC-cables.html2. For ac & dchttp://www.powerstream.com/Wire_Size.htmBut this is not for exact dc. need to select AWG first.Got idea from these two. But any more info on this also?

author: ConKbot
author_rank: Super Contributor
timestamp: March 28, 2017, 05:36:15 pm
content: For the mains, you have the wattage figured out correctly, and you're looking at 6-7A if it was a resistive load. But with 75 percent efficiency I'm guessing the PFC was skimped on, so figure a PF of 0.6, so 7A/0.6=11.6A I'd run 14AWG or 1.75/2.0 mm2 wire for that.As far as the DC output, on low voltage high current outputs, usually voltage loss is an issue before wire heating. If you allow a 1V drop, (About 2 percent in this case) you need to keep your wires under 50 miliohms (1V/20A) so 25 milliohms each for red and black. Use a chart to figure out your minimum wire size (i.e.http://www.powerstream.com/Wire_Size.htm), and then use resistance to figure out how big of a cable you need for longer runs. I.e. A 14 awg cable would hit 0.025 ohms at around 3 meters, so use it for anything under 3m. 10AWG/5.25mm2 would work for about 7.5 meters.For mains, generally I use 18AWG for everything under 10A, 14 AWG for under 15A and 12AWG for under 20. Your mains cord has to be beefy enough to not burst into flames when its overloaded and waiting for the breaker to trip. As you can see on that table 18 AWG is fine with 16A so the usual US/EU breakers will protect the lead fine. If you live on an island where numpties decided a 32A outlet for all household appliances is reasonable then a fused plug is advised.
Calculate complex relative permittivity for a material - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: August 13, 2018, 12:11:57 pm
content: I need to calculate the dielectric heating power for a paricular material.From herehttps://en.wikipedia.org/wiki/Dielectric_heatingI got the formula for heating power is\$Q = \omega \cdot \epsilon^{''}_{_{r}}\cdot \epsilon_{0} \cdot E^{2}\$I get other parts but am stuck on\$\epsilon^{''}_{_{r}}\$ which wiki says is the "is the imaginary part of the complex relative permittivity of the absorbing material".

author: iMo
author_rank: Super Contributor
timestamp: August 13, 2018, 12:40:36 pm
content: It seems you better have to find a more simplified version of the formula, as the one you try elaborate is pretty difficult to mess with. Look at"Complex Permittivity"on wikipedia.

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: August 13, 2018, 01:16:56 pm
content: Quote from: imo on August 13, 2018, 12:40:36 pmOK, but say I have additional parameters regarding the material1. the relative permittivity2. The dielectric loss tangent (\$tan \delta\$)Is it possible to derive "Epsilon R double dash" from these?

author: iMo
author_rank: Super Contributor
timestamp: August 13, 2018, 01:36:05 pm
content: epsilon_double_dash (function of omega) = |D0/E0|*sin(delta)Still the whole stuff is not manageable easily, imho. There must be some engineering tables or simple equations available too..
Calculate dB on a slide rule? - Page 1
Forum section: electronics / beginners

author: CaptDon
author_rank: Super Contributor
timestamp: October 04, 2025, 12:52:59 am
content: I have a beautiful Post 1460 Versalog slide rule. I can do basic multiplication and division. What scales would I use to prove that 3dB would be a voltage ratio of .7079 or 1.413 or a power ratio of .5012 or 1.995? I can't seem to find a direct correlation between these numbers on the scales. I used the slide rule mainly for XL or XC in R.F. electronics years ago. I pulled this beauty out several times just fooling around. Mine is in the leather hip holster. I ran across an identical 1460 at the Berea (Cleveland) hamfest last weekend. It was in the two piece snap together gray plastic case. Cheers all!! Thanks!!

author: Analog Kid
author_rank: Super Contributor
timestamp: October 04, 2025, 01:41:10 am
content: Quote from: CaptDon on October 04, 2025, 12:52:59 amSo do I. Same one. Mine is sitting next to me as I type. And yes, it is beautiful.Unfortunately I can't help you here. But I hope to someday (finally!) learn how to use this instrument. And calculating dBs would be nice.WatchedApollo 13last night, and didn't miss the detail of the ground control guy grabbing his slide rule to verify the numbers that the astronaut radioed down for the thruster burn duration.

author: BeBuLamar
author_rank: Super Contributor
timestamp: October 04, 2025, 01:45:56 am
content: Check this outFor your example voltage ratio of 3dB. You would either mentally or use the slide rule to divide by 20 and get 0.15. Set the cursor at 0.15 on the L scale and read ratio on the D scale. That is for +3dB. For -3dB line up the C and D scale then read the value on the CI scale.

author: CaptDon
author_rank: Super Contributor
timestamp: October 04, 2025, 01:46:18 pm
content: Great tip and link to the video!! I will have time Sunday to sit in my workspace and try some calculations and write some notes so I don't forget a year from now. I used to do simple functions on the slide rule about as fast as my co-workers could type them in on a calculator. I was good to 4 or 5 digit accuracy which was more accurate than the tolerance of the parts in our designs. Of course the 'calculator guys' were easily good to about 8 digits.
calculate design e.g. quad 303 amplifier board - Page 1
Forum section: electronics / beginners

author: apper
author_rank: Contributor
timestamp: August 25, 2020, 09:31:03 am
content: Hi All,Any pointers in getting started on howto to completely calculate (by hand or SW) e.g. a quad 303 amplifier board or in general any other design.Am curious about how to Pro's would tackle this.RegardsAart

author: magic
author_rank: Super Contributor
timestamp: August 25, 2020, 11:23:06 am
content: 1. learn the behavior of your components2. learn circuit topologies3. ??4. profitIf you want to know more about audio power amps, Cordell and Self wrote whole books on that (both titled "design of audio amplifiers" or similar). Cordell covers more topologies, Self is more autistic about detailed analysis

author: apper
author_rank: Contributor
timestamp: August 25, 2020, 12:32:23 pm
content: Maybe i need to clarify: i meant with calculate doing the math of the circuit before building.

author: Simon_RL
author_rank: Regular Contributor
timestamp: August 26, 2020, 09:37:21 am
content: Quote from: apper on August 25, 2020, 12:32:23 pmI recommend you take Magic’s advice. I have both books and you will learn a lot from them. All the math you need is in them. I recommend both books as they are different takes on the same subject and you will gain a great deal of insight.
Calculate in  a series circuit with 10 hidrogen fuel cells the voltage total if  - Page 1
Forum section: electronics / beginners

author: INFINIUM
author_rank: Contributor
timestamp: November 01, 2018, 07:49:27 pm
content: one fail, each one produce one volt in good condition , like the ones used in the APOLLO 13 .??Of course if the cell is open there is not voltage and you need to return to earth coldif the hidrogen cell is bad or not produce any power the total voltage is, I saw, 8 volts not 9!with another batteries in U BOATS Submarines in movies similaar problem ,that is why in the submarine movies they made shortcircuits in the cells with salty water to prevent less or not voltage in the ouput.

author: Simon
author_rank: Unknown
timestamp: November 01, 2018, 08:30:35 pm
content: what?
calculate low pass - Page 1
Forum section: electronics / beginners

author: Mepakos
author_rank: Contributor
timestamp: September 11, 2019, 08:43:59 am
content: Can u help me pls? Dont know if i am right or wrong.

author: ledtester
author_rank: Super Contributor
timestamp: September 11, 2019, 09:03:42 am
content: Um, your first mistake is here:

author: ledtester
author_rank: Super Contributor
timestamp: September 11, 2019, 09:29:41 am
content: Another thing you have to be more careful about are the signs on your exponents:It should be 10^-6. This doesn't cause a problem since you make the same mistake later on and the two cancel each other out.

author: GerryR
author_rank: Frequent Contributor
timestamp: September 11, 2019, 12:00:32 pm
content: You don't need to consider the source impedance (50) in your calculation. You handle the lo-pass as a regular voltage-divider network to find the "pole." Try looking up Bode Plots to find how to find your poles and zeroes and phase for different networks.

author: ledtester
author_rank: Super Contributor
timestamp: September 11, 2019, 12:20:52 pm
content: Quote from: GerryR on September 11, 2019, 12:00:32 pmLike this:http://sim.okawa-denshi.jp/en/CRlowkeisan.htm

author: Mepakos
author_rank: Contributor
timestamp: September 16, 2019, 08:10:51 am
content: Is this good?

author: GerryR
author_rank: Frequent Contributor
timestamp: September 16, 2019, 01:53:32 pm
content: Figure out the impedance of the capacitor at 480 KHz, then use that in your voltage-divider formula to find the output voltage at that frequency [(Zc / R+Zc) * Ve]

author: avogadro
author_rank: Contributor
timestamp: September 16, 2019, 10:11:02 pm
content: Zc = 1/(2*pi*f*C) = 1/(2*pi*480E3*3.3E-9) = 100.5 ohmUA = U0*(Zc)/(Zc+Ri+1Kohm) = 1*(100.5)/(100.5+50+1000) = 0.0874V
Calculate PNP base resistor value - Page 1
Forum section: electronics / beginners

author: scott216
author_rank: Regular Contributor
timestamp: April 11, 2014, 02:21:04 am
content: I want to confirm if i calculated a base resistor for a PNP transistor correctly. Attached is the schematicI have an 8550S transistor.I found a Data Sheet here:http://www.digchip.com/datasheets/parts/datasheet/670/8550S-D-T92-B-pdf.phpI don't know if it's the right manufacturer or not.I'm assuming there are 20mA going through the diodes. For the base current calculation, I assumed a beta of 100. So that give me 0.2mA (20ma/100) at the base. I am going to have an Arduino control the transistor. To turn on a PNP I bring the base to zero. I'm assuming a 1 volt drop across the transistor - I got this VBEin the data sheet, but I'm not positive I picked the right number. That means my resistor has to drop 4 volts at 0.2mA which equals 20k ohms.As you can see in the schematic, my diodes don't go to ground but to -9 volts. I'm hoping that's not an issue with the circuit working properly.This is a circuit that already exists and I'm trying to get an Arduino pro-mini (3.3v version) to interface with it. I guess that bring up another question, is 3.3 volts enough to turn the transistor off?If this isn't going to work, I can desolder the transistor and put in something else in it's place, but I can't change any "wiring" around since it's on a PCB.

author: edavid
author_rank: Super Contributor
timestamp: April 11, 2014, 03:09:24 am
content: Quote from: scott216 on April 11, 2014, 02:21:04 amIf you are running the AVR from 3.3V, you need to connect the transistor emitter to 3.3V.Otherwise you are doing the calculation properly.You might want to use a lower beta value (50?) to make sure the circuit will work with any crappy transistor.

author: scott216
author_rank: Regular Contributor
timestamp: April 11, 2014, 04:26:06 am
content: Quote from: edavid on April 11, 2014, 03:09:24 amI have 5 volts going into my AVR, but it's voltage regulator reduces it to 3.3 volts. I could connect the PNP transistor to 3.3 volts. I'd also have to swap out the 390 ohm resistor for a smaller one, but that's easy.

author: ttp
author_rank: Regular Contributor
timestamp: April 11, 2014, 09:14:44 am
content: As edavid mentioned you need to connect emitter to 3.3V. If you using the transistor as a switch it usually means you want to drive it into saturation - don't make base current just 0.2mA but 1-2mA to fully open it. Don't worry about LED current, the series resistor (390R or whatever you'll change it to) will control and limit it. Actually you can experiment with different base resistors and see how the collector-emitter voltage changes with different base currents.
Calculate power and thermal design - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: March 21, 2020, 05:18:51 pm
content: Hi,I have a simple application but, even after watchingI'm still not capable of understanding how to dimension and calculate things.Basically I have a n-FET(FQP30N06L)which I want to use to switch an ≈8W load. The load will require around 2A at 3.8V.I will drive the fet at 5V.What I'd like to understand is how to calculate how much power will be dissipated into the fet, in order to understand whether it will require some kind of cooling and what temperature I'm supposed to expect the FET will reach.I tried taking 2A with the max static resistance indicated in the datasheet (0.045at 5V).This gives me 0.18W. Is this ok?Assuming it is, for the tranny's temperature above ambient, I multiplied that by the junction to ambient resistance (62.5 °C/W) obtaining 11.5°C. Is this the correct calculation?Thanks

author: bob91343
author_rank: Super Contributor
timestamp: March 21, 2020, 08:39:06 pm
content: It's unclear to me just what you are planning. First you say you are switching but you give no details. When estimating the wasted power in a switching FET, you need to take into account the frequency, switching speed, saturation voltage, etc. and compute the losses for each portion of the cycle. Each loss occurs once per cycle and the number of cycles per second will determing the total steady power to be dissipated.Once you have that, it's easy enough to see how much temperature rise to expect. Regardless of this, you will still need a breadboard to verify the calculations.

author: Moriambar
author_rank: Unknown
timestamp: March 21, 2020, 09:29:21 pm
content: Quote from: bob91343 on March 21, 2020, 08:39:06 pmHi. First of all, thanks for your reply. Perhaps I misspoke. I'm not switching at high frequency, no pwm of sort. I'm just switching the load on for, let's say, 15-20s then it stays off for 10-15 minutes; sometimes more, sometimes less.I don't actually know what else to say, except that is a power load of around 2at 3.8-4V thus it will draw roughly 2A.Given that I don't know whether what I calculated is ok, or what else to say…

author: twospoons
author_rank: Frequent Contributor
timestamp: March 21, 2020, 09:42:03 pm
content: For the situation you are describing your calculation is correct. And that mosfet should be able to handle that heat load without any additional heatsink.
Calculate PT100 resistance value from attached circuit - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: August 28, 2022, 09:17:33 am
content: 1. Attached is one analog circuit, whose output I can measure.2. Its three wire PT100 whose resitance I have to measure. RL1=RL2=RL3 is lead wire resistance.3. Rs1=Rs2 we can take which is resistance of anlog mux displacyed here as switch for simplicity.4. Output opamp is conencted with gain of 100. After which I can measure voltage by MCU.5. I can measure two voltage:a) when switch is top positionb) when switch is at botton position6. Now who to caluclate PT100 resistance from this?I tried using thevnin equivalent diagrams but they become very complex with lots of variables.Need to implement it in MCU.

author: ledtester
author_rank: Super Contributor
timestamp: August 28, 2022, 02:14:29 pm
content: The circuit simplifies a lot when you consider it. For instance, when the switch is in the upper position you can ignore R34. And when it is in the lower position you can ignore R33.First fix the position of the switch into one specific position. Then the schematic looks like what I've drawn below and you want to find the voltage at X.Then notice that V7 and V8 are the same so you can draw it as shown in the right hand diagram.Now compute the voltage at Y using a voltage divider calculation. Next compute the voltage at X using a voltage divider calculation between 2.5V and Y.When the switch is in the upper position the resistances are:R1 -> R27R2 -> R32R3 -> RL3 + PT100 + RL1R4 -> R31 + Rs1 + R33 + RL1When the switch is in the lower position the resistances are:R1 -> R27 + RL1R2 -> R32R3 -> RL3 + PT100R4 -> R31 + Rs2 + R34 + RL2The formula you will get for the voltage at X will be a rational function of R3, i.e.:$$ X = \frac{A + B R_3}{C + D R_3} $$This can be solved for \$R_3\$:$$ R_3 = \frac{A-CX}{X D - B} $$Update: This reminded me of this symbolic circuit analysis project:https://www.eevblog.com/forum/crowd-funded-projects/symbolic-circuit-analysis-upcoming-kickstarter/msg4022044/#msg4022044

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: September 04, 2022, 10:28:58 am
content: 1. THis analog part is someone else design, cannot change. I have access of circuit on MCU side & can read output of opamp.2. So considered R32=open due to high value, R31,R33,R34.Rs1,rs2 as wont happen happen much effect on output, as these goes on high input impedance opamp. (thanks to @El Tangas for suggestion)3. Below is equation which comes out, considering R27,Rl1, rl2 & Rl3 in circuit. Rl1=Rl2=Rl3 is taken. Lets call it reduced circuit.Rp = (60000V2 - 30000V1) / (6.25 - 2.5V1 - 2V1V2)where Rp= resistance of PT100V1 & V2 are voltages measured at the input of opamp when switch is at top & bottom4. Tried simulating circuit on multisim with reduced circuit & matched values with this formula, seems like ok.5. Is equation can be solved by also considering R31,R33,R34.Rs1,rs2 . I tried but equation starts very complex.Simulating original circuit, with reduced circuit equation does not work actually.
Estimate silicon rectifier forward current as a function of time - Page 1
Forum section: electronics / beginners

author: king.oslo
author_rank: Frequent Contributor
timestamp: May 18, 2013, 12:31:36 pm
content: Hello there,I am interested in the HVP12 HV diode. Across the diode I need 0V which ramps up to 325V. I need to determine the desired rise time of that voltage. In order to do this, I guess I must know what kind offor the diode.What is the equation to calculate or estimate silicon rectifier forward current as a function of time (and VF, perhaps)?Thanks.M

author: Paul Price
author_rank: Super Contributor
timestamp: May 18, 2013, 12:52:43 pm
content: The forward current though any diode is almost instantaneous and current starts to flow in a sub-nanosecond time after voltage is applied. You don't need to know Di/Dt unless the diode of interest is an DIAC or the anode and cathode of a TRIAC or SCR. Look at the data sheet(alldatasheet.com) for your diode to see switching voltage waveforms and forward voltages v. current. Most ordinary silicon diodes do not start to conduct current(microamps) until after approx .65V of voltage has been applied(room temperature) and the voltage rises up to 1.2V to 1.5V approx when the current approaches the maximum allowable for the diode. At higher temperatures, the threshold forward voltage of conduction will decrease with temperature at a rate of approx. -2.2mv/deg C of temperature difference from room temp.What is often more important is the type of diode. Schotkey diodes will conduct with faster turn on and faster turn off and have a forward threshold voltage of .12V to .18V with a milli-amp of current noticed, depending on the diode.

author: king.oslo
author_rank: Frequent Contributor
timestamp: May 18, 2013, 01:17:51 pm
content: Quote from: Paul Price on May 18, 2013, 12:52:43 pmAre you saying silicon (not schottky)HVP12 has tRISE< 1ns to its peak current?M

author: Paul Price
author_rank: Super Contributor
timestamp: May 18, 2013, 02:05:50 pm
content: No, a slow diode rectifier like (!N4003) will be much slower than this <nS, one can only to notice a forward current in the high uA to 1 mA range after a few nS.

author: king.oslo
author_rank: Frequent Contributor
timestamp: May 18, 2013, 02:46:12 pm
content: The datasheet for the HVP12 says nothing about this (as far as I can tell). Here is a link:http://www.mouser.com/catalog/specsheets/hvp.pdfIt is critical to the efficiency of the application to know time it takes to reach about 60% of peak surge current 50A. How can I estimate this time?Thank you for your time.Kind regards,Marius

author: Paul Price
author_rank: Super Contributor
timestamp: May 18, 2013, 03:10:09 pm
content: See the attached files...learn to goooooooogle!
Calculate solder temp/time for GND pins for large GND plane - Page 1
Forum section: electronics / beginners

author: 2xA
author_rank: Newbie
timestamp: May 08, 2018, 05:53:01 am
content: HiI am working on a THT board, which is gonna be large compared to what i normally do.I wonder if the GND pins will be hard to solder, because of the large area of GND plane?How can I calculate the required temp/time to solder these pins? What is recommended values?The plane is 350x270mm and i use 0.2mm thermal vias, one(worst case) via is 1.0mm drill and 2mm in diameter.I appreciate any help you can and will provide2xA

author: Benta
author_rank: Super Contributor
timestamp: May 08, 2018, 01:42:59 pm
content: The standard way of solving this is making cutouts in the copper around the ground pine.

author: GerryBags
author_rank: Frequent Contributor
timestamp: May 08, 2018, 04:24:42 pm
content: I may be mistaken, but I think it has more to do with the wattage than the temperature, which will go down as it is conducted away by the ground plane. You have to have an iron that will supply enough power to keep the temperature up. If you simply raise the temperature to try and compensate for low-wattage you will have steeper heat gradients which may effect the part being soldered before getting enough heat into the ground plane to make the connection.

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: May 08, 2018, 10:17:08 pm
content: Even with thermal reliefs you may still have issues with a low thermal capacity iron, in which case pre-heating the board is a good solution.

author: 2xA
author_rank: Newbie
timestamp: May 14, 2018, 05:25:28 am
content: Thank you very much for your reply's.Quote from: Benta on May 08, 2018, 01:42:59 pmI agree, but i am not sure that i have a problem jet? and if there is a problem how will I know how much I should cut out?Quote from: GerryBags on May 08, 2018, 04:24:42 pmYou are absolutely right it should be watt insteadQuote from: RobertHolcombe on May 08, 2018, 10:17:08 pmunfortunately I only have access to a heat gun, which could be done but its time consuming
Calculate temperature-rise for DC/DC converter - Page 1
Forum section: electronics / beginners

author: Spike101
author_rank: Contributor
timestamp: August 30, 2016, 12:37:56 pm
content: Hi,I need a DC/DC converter that converts 12V to 24V with an output current of about 1.5A. I was thinking about using this one:S24SP24002PDFA -http://www.deltaww.com/fileCenter/products/download/01/0102/datasheet/DS_S24SP24002.pdfBut I can't figure out how hot it's going to be at 1.5A output current. From the graph on the top right side on P3 of the datasheet I assume that the power dissipation will be about 3.5W. But I can't find a ThetaJ-A value or something else in °C/W (maybe i'm just overlooking it somehow). Or is there some other way to calculate the temperature rise?Thanks,Sebastian

author: Spike101
author_rank: Contributor
timestamp: August 30, 2016, 03:34:25 pm
content: Good idea (i would have never found that way of calculating it..)!Thanks!
Calculate Total Over Tme - Page 1
Forum section: electronics / beginners

author: john21443
author_rank: Contributor
timestamp: August 02, 2015, 10:22:51 pm
content: This is a math question and not specific to electronics design. Any assistance (even high level) would be appreciated.I have a series of data points that represent point in time and current drawn at that point. Data may have gaps in it. For example, the typical data point will be every 30 seconds but arbitrary points might not exist. Also, I may want total current over last 8 hours but there is only 6 hours worth of data.How do I calculate total current draw over a time period?I could probably average the current values and use total time difference but am not grasping the method used to utilize the full resolution of the data.Thanks,John

author: dadler
author_rank: Unknown
timestamp: August 02, 2015, 10:56:54 pm
content: You need to use calculus, essentially interpolation between the points, summing the "area under the curve". There are many ways of doing this, with various tradeoffs/complexities/error.See:https://en.wikipedia.org/wiki/Numerical_integrationhttps://en.wikipedia.org/wiki/Rectangle_methodhttps://en.wikipedia.org/wiki/Trapezoidal_rulehttps://en.wikipedia.org/wiki/Simpson%27s_rule

author: john21443
author_rank: Contributor
timestamp: August 02, 2015, 11:03:44 pm
content: Perfect...thanks!
Calculater voltmeter reading with internal resistance - Page 1
Forum section: electronics / beginners

author: lumdef
author_rank: Contributor
timestamp: October 05, 2024, 03:10:12 pm
content: The task and my attempt to solve it are on the picture. The book gives 72.8 mA; 34.3 mA, 1.93 V as an answer. I am not sure I understood the task, and therefore drew the circuit correctly. I tried to do mesh analysis, but it does not yield the correct results.

author: Kurets
author_rank: Regular Contributor
timestamp: October 05, 2024, 09:09:37 pm
content: It seems you are drawing the circuit correctly. I will ignore the 1Ohm in my explanation.The middle cell has so low impedance that it will completely dominate the voltage across the voltmeter. The voltage across 50ohm is therefore approximately 2V and you get 40mA to the meter. In the left part of the circuit you have 3.5V applied across the 100ohm resistor which results in 35mA though it.So you will have approximately 40+35mA through the 2V cell, and 35mA through the 1.5V cell.These numbers are not exact, as they ignored the 1Ohm output resistance of the 2V cell, but it shows that the answer from the book is correct.

author: radiolistener
author_rank: Super Contributor
timestamp: October 06, 2024, 06:29:18 am
content: U1 - I1*R1 - (I1+I2)*R3 = 0 => (R1+R3)*I1 + R3*I2 - U1 = 0 => 150*I1 + 50*I2 + 1.5 = 0U2 - I2*R2 - (I1+I2)*R3 = 0 => R3*I1 + (R3+R2)*I2 - U2 = 0 => 50*I1 + 51*I2 - 2 = 0150*I1 + 50*I2 + 1.5 = 0 => I2 = -3*I1 - 0.0350*I1 + 51*(-3*I1 - 0.03) - 2 = 0 => I1=3.53/-103=−0.0343 AI2 = -3*(3.53/-103) - 0.03 =0.0728 AI3 = I1 + I2 = −0.0343 + 0.0728 =0.0385 AU3 = I3*R3 = 0.0385*50 =1.925 V

author: lumdef
author_rank: Contributor
timestamp: October 06, 2024, 08:13:14 am
content: My problem was that I wrote KVL equations incorrectly, here is the right way...
Calculating Amp/Hours over 24 hour Period - Page 1
Forum section: electronics / beginners

author: Veramacor
author_rank: Regular Contributor
timestamp: December 09, 2012, 04:16:17 pm
content: Hello again,Mental Block time. I have a PIC circuit that will draw 35 milliamps for 300 seconds out of every 24 hour day. I put the PIC to sleep for the the rest of the time so It draws about .1 microamps so for the sake of making the calculation easier I am ignoring that for now.I am trying to figure out battery life in days. Is it correct to estimate the effective milliamp hour draw by doing:60 seconds * 60 minutes * 24 hours = 86400 seconds in a day86400 seconds - 300 seconds = 86100 seconds in a day the PIC is asleep (ignoring for now)Spreading 35 milliamps over 24 hours:300/86400 = .00347.00347 * 35 milliamps = .121 milliamps or 121 microamps.So is this a valid way to spead the millamps over a 24 hour period? In other words, instead of having a 35 millamp burst for 300 seconds, can I say I have a constant current over a 24 hour period of 121 microamps?If this is the case, If I had a 2000 millamp/hour AA battery, and I had a constant current draw of 121 microamps:2000 ma/h / .121 ma = 16528.9 hours or 688 days. FYI I'm using 2000 ma/h from the following website for a AA battery:http://www.techlib.com/reference/batteries.html

author: w2aew
author_rank: Super Contributor
timestamp: December 09, 2012, 05:06:28 pm
content: 35ma for 300 seconds out of each day...35ma * 300sec * 1min/60sec * 1hr/60min = 2.9mAhr consumed each day.Assuming 2000mAhr is the right capacity, then the battery would last:2000mAhr / 2.9mAhr per day = 685 daysYeah, so you got it basically right. However, you'll find that the amphour rating for batteries will be load dependent. It will likely be greater than 200mAhrs. But, given this long operational life, there will probably be self-discharge too.

author: Unknown
author_rank: Unknown
timestamp: December 09, 2012, 05:18:11 pm
content: You appear to be confused about units. Battery capacity is measured in A * h, for example 2000 mAh. Your circuit draws 35 mA * 300 s = 10500 mA * s = 2.9 mAh per 24 h period, or an average current of 2.9 mAh / 24 h = 122 uA. The battery can deliver 2000 mAh, so it should supply 122 uA for about 2000 mAh / 122 uA = 16457 h.As a first approximation this is correct. Other factors that you may have to take into account:- self discharge, forget 1 year of battery life with regular (non-LSD) NiMH batteries, self discharge is higher than this.- battery voltage will drop as the battery discharges, depending on your power supply you may be able to use more or less of this capacity.- loss due to output impedance. Dave discussed this in his very early video about the HP 20b calculator (EEVblog #4). I wouldn't expect this to be an issue since 35 mA is a very small current for an AA cell.
Calculating bandwidth of PCI bus - Page 1
Forum section: electronics / beginners

author: MrOmnos
author_rank: Frequent Contributor
timestamp: April 06, 2016, 12:48:20 pm
content: Hi, I know this is a really dumb question to ask but I don't seem to get my head around it,So, generally Bandwidth = Bus width x Clock frequencyso I read somewhere that for a 66Mhz bus of width 64 bits bandwidth is66 Mhz x 64 Bits = 518MB/sHow?? Please walk me through the calculation. Thanks

author: Kilrah
author_rank: Unknown
timestamp: April 06, 2016, 01:02:33 pm
content: Mixing bits and bytes?

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: April 06, 2016, 01:13:16 pm
content: 66000000 Hz * 68 bit = 4224000000 bit/s = 4224 Mbs4224000000 / 8 = 528000000 byte/s = 528 MBs

author: MrOmnos
author_rank: Frequent Contributor
timestamp: April 06, 2016, 01:23:43 pm
content: Quote from: alexanderbrevig on April 06, 2016, 01:13:16 pmlol thanks!!

author: senso
author_rank: Frequent Contributor
timestamp: April 06, 2016, 02:06:52 pm
content: ANd dont forget about the 8/10b in PCIe 1/2 or the 128/130b in the PCIe interfaces, so you get a bit less usable bandwidth.
Calculating C for a homebrew butterfly cap - Page 1
Forum section: electronics / beginners

author: apelly
author_rank: Unknown
timestamp: October 14, 2017, 10:03:37 pm
content: The more I think about this, the more I think my original assumption was wrong.Wikipediatell us that \$C=\epsilon_r\epsilon_0\frac{A}{d}\$I'd first thought that \$A\$ would be 4 times the area of one rotor wing. ie. 2 wings (B & D) with two sides each. But now I'm inclined to think it's 1/2 that because the rotor is electrically isolated.Following on from that, I'm also thinking that \$d\$ is effectively doubled because there is a \$d\$ on each surface of the rotor.\$\Large C=\epsilon_r\epsilon_0 \frac{Area\ of\ \mathsf B\cdot two\ surfaces}{(\frac{distance\ between\ stator\ plates - plate\ thickness}{2})\cdot two\ surfaces}\$Would someone give me a hint about this please?

author: chris_leyson
author_rank: Super Contributor
timestamp: October 14, 2017, 10:17:55 pm
content: Capacitance between rotor and either stator is 4 times. I figured the rotor would be grounded but as you said it is electrically isolated then the capacitance is 2 times.

author: Benta
author_rank: Super Contributor
timestamp: October 14, 2017, 10:42:33 pm
content: It's pure geometry.Take the "B" area and multiply by 4. That's one side.Take the "D" area and multiply by 4. That's the other side.Use the same "d" for all calculations.Place B and D caps in series (divide by 2). That's the result.

author: apelly
author_rank: Unknown
timestamp: October 16, 2017, 08:24:07 pm
content: Quote from: Benta on October 14, 2017, 10:42:33 pmThat makes sense. Thanks.