hybridfree/eevblog-posts huggingface dataset:
Questions on replacement fuse for the very Fluke 87 - Page 1
Forum section: electronics / beginners

author: zoltm
author_rank: Contributor
timestamp: March 28, 2012, 03:11:54 pm
content: Hi guys,This is my first post, I have recently adopted a friend's well used Fluke 87. This is my first serious multimeter. I feel like a real man holding that chunky multimeter, it feels good. I have to say.However, I was reading around the service document of the 87 and tried to test the fuses, F1 (1A) and F2. (15A). It's found that the F1 (1A) fuse is blown. Also, it's found that my 87 is the one from the very first generation, with a s/n < 65650000.Then I tried to source the 600V 1A fuse locally, to my dismay, it's not readily available. I check with RS Components, Farnell and Digikey. None of them have it. My questions is,1. Is there any other options? Like using the 440ma @ 1000V that is readily available from RS Components.Thanks.zoltm.

author: armandas
author_rank: Frequent Contributor
timestamp: March 28, 2012, 05:35:51 pm
content: The new models use 440mA and 11A fuses, IIRC. If they fit - use them. Lower current rating fuses won't do any damage to your meter.

author: zoltm
author_rank: Contributor
timestamp: March 28, 2012, 05:49:45 pm
content: Quote from: armandas on March 28, 2012, 05:35:51 pmThis is the thing I would like to know, if I can indeed use the 440ma and 11A fuse instead. Those are readily available at RS. However, per this Fluke web site,http://www.fluke.eu/comx/service.aspx?locale=HKen&fuse=1it's clearly shown that the 87 with s/n > 65650000, all use 440ma and 11A fuse.But mine is one with s/n < 65650000. As long as it still offer the appropriate protection, I don't mind using the 440ma and 11A, just want to be sure of being a newbie.

author: ron
author_rank: Regular Contributor
timestamp: March 28, 2012, 05:52:48 pm
content: F-1A,600V - FGhttp://www.flukeonlinestore.com/3478694.html

author: zoltm
author_rank: Contributor
timestamp: March 29, 2012, 04:59:59 am
content: Quote from: ron on March 28, 2012, 05:52:48 pmThanks, I am indeed aware of this. Problem is I am not US domestic. Not sure if Fluke Store in US would sell internationally and the shipping cost is likely as much as the fuse itself (if not more).Best is some authority could comment if I can indeed use the 440ma fuse in the meter. Sorry for my ignorance, I mistakenly thought that the meter would not work when the fuse is blown. Out of curiosity, I experiment, the meter could indeed work WITHOUT the fuse, if I use only the COM and V.

author: retiredcaps
author_rank: Super Contributor
timestamp: March 30, 2012, 05:08:32 am
content: Quote from: zoltm on March 29, 2012, 04:59:59 amI hear you. The sellers on ebay want $12.99 for shipping to Canada for a single fuse.

author: kaptain_zero
author_rank: Regular Contributor
timestamp: March 31, 2012, 12:37:24 am
content: Send an email tomailto:canadaservice@fluke.comand ask if they can supply the part or if you can use the new size. That should clear things up with the word straight from "the horse's mouth".RegardsChristian
Questions on two-port network - Page 1
Forum section: electronics / beginners

author: promach
author_rank: Frequent Contributor
timestamp: September 26, 2017, 08:03:25 am
content: For z-parameter model:a) How to derive the two equations in the screenshot below which are retrieved fromhttps://en.wikipedia.org/wiki/Impedance_parameters#Impedance_relations?b) Why is output impedance, Zout computed with input node shorted to ground ?For Y-parameter model:a) As shown below , why "Though allowing simpler algebra, the Y model does not provide intuitive results." ?b) As inhttp://rfic.eecs.berkeley.edu/~nikne...ct4.pdf#page=6, why " y21 =gm - y? " ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 26, 2017, 08:13:23 am
content: a. Literally, just write down the port voltages and currents, and rearrange into the canonical impedance form. (Any other two-port form can be reached by rearranging the equations as well.) Recall the definition of a vector and a matrix in a system of equations.b. The picture says it's computed for input node connected to Zs.Tim

author: promach
author_rank: Frequent Contributor
timestamp: September 26, 2017, 08:19:04 am
content: The screenshot is for question (a)

author: danadak
author_rank: Super Contributor
timestamp: September 26, 2017, 12:10:43 pm
content: Keep in mind the Z of an ideal V source is 0 and of a current source infinity.Makes for quick shortcuts when configuring two port for calculations.Regards, Dana.

author: The Electrician
author_rank: Frequent Contributor
timestamp: September 30, 2017, 07:36:33 am
content: Often the situation is idealized by assuming the input of the network is driven by a voltage source. Voltage sources have zero output impedance, so when the input node is driven from a voltage source, this is the same as shorting the input node to ground as far as impedance seen at the input node is concerned.You might need to show Fig. 8.51(a) to help us see what might be more intuitive about the G model equations.

author: The Electrician
author_rank: Frequent Contributor
timestamp: October 02, 2017, 01:20:52 am
content: I don't see immediately why the Y model would be easier algebra but less intuitive. It might be necessary to work out the result using the Y model; perhaps then it would be obvious.
Questions re building a 5V linear power supply - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: February 06, 2022, 12:05:24 pm
content: I would like to build a small very electrically quiet power supply to run several (perhaps 4) KiwiSDR receivers. They draw a maximum instantaneous current of 2 Amps each, but idle at far less. I can't see any 5V voltage regulators that would handle more than 2 Amps, so if I used an adequately rated transformer could I use several 5V at 2 Amp regulators on the same secondary winding and have multiple output sockets? Or would I be better with one regulator and a big pass transistor? Thanks.

author: Zero999
author_rank: Super Contributor
timestamp: February 06, 2022, 12:42:25 pm
content: There are many:L78S05LM350LM338I'd go for switched mode with loads of filtering.

author: mariush
author_rank: Super Contributor
timestamp: February 06, 2022, 12:47:00 pm
content: Plenty of linear regulators that can do 2A ...For example a very common one is LM1085 and other *1085 (made by other companies), it can do 3A :https://www.digikey.com/en/products/filter/pmic-voltage-regulators-linear/699?s=N4IgTCBcDaIIwAYAcBWEBdAvkA*1084 is rated for 5A :https://www.digikey.com/en/products/filter/pmic-voltage-regulators-linear/699?s=N4IgjCBcoLQExVAYygFwE4FcCmAaEA9lANogCsIAugL7X4KSlgAMAHACxX4BsiIAlgBMoIGCwj4ADqhEh8qAJ6TsIgIYBnFLSAAnother good one is MIC29310, MIC29301 ... and you have adjustable regulators that do more than 2A :https://www.digikey.com/short/zn72rhmwAnother option would be to use a step-down / buck dc-dc converter - you can buy such converters ready made from eBay for 1-2$ or you could make your own with a chip, an inductor, maybe a diode and a bunch of small ceramic capacitors and resistors.If you get synchronous rect. chips the diode may not even be needed... .see for example AP62300, look at datasheet as you have shematic on first page for 5v output :https://www.digikey.com/en/products/detail/diodes-incorporated/AP62300TWU-7/12702558It will also be 90% efficient so you could use a 12v adapter and not worry about dissipating half of the power as heat in a linear regulator

author: ledtester
author_rank: Super Contributor
timestamp: February 06, 2022, 12:51:14 pm
content: I would suggest looking at getting a commercial unit such as this one:Power-One HN5-9/OVP-A Power Supply 5VDC 9A w/ OVP 100/120/220/230/240Vhttps://www.ebay.com/itm/154600988372
Questions regarding IR2110, half bridge driver - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: September 07, 2018, 08:57:53 pm
content: For testing a solenoid I built a H bridge circuit made of 4x IRF540'sANd I am driving each half brdige arm with a IR2110.I have taken inspiration from this circuit diagramExcept that my Vdd = 5V and Vcc = 15V and I have ommited theCurrently I have kept IN2 open and and after pulsing the pin IN1 I was hoping for an output at the bridge but I don't get any.I am not using PWM just triggering a 1ms pulse.My question is can I use the IR2110 this triggered mode. From what I have heard is that the way this driver works is the lo side fet needs to be switched on to charge the bootstrap capacitor. And this works well in PWM driven circuits. Since the low side fet comes on regularly and charges the bootstrop capacitor.To recharge the bootstrap capacitor in pulsed mode do I have to implement some additional logic so that its necessary lo side mosfet first eg. Q2 and then send the triggering pulse to switch on Q1 / Q4.However my circuit is wired up like the diagram above with just 2 inputs.
Questions regarding ordering from digikey for a product - Page 1
Forum section: electronics / beginners

author: JamesP
author_rank: Newbie
timestamp: January 13, 2018, 01:52:24 pm
content: Im ordering to sweden from digikey in the states for the first time and im just wondering about the "Will Components Purchased from Digi-Key be resold by you in their purchased form?" option.1. Since im selling a kit, i would assume this is a 'yes'. But is this the case in a pre-assembled product?2. Will there be any changes in price/whatnot i should be wary about?

author: MrAl
author_rank: Super Contributor
timestamp: January 13, 2018, 02:56:19 pm
content: Hi,Sounds like it could be all about tax collecting. If you have a tax number they may not charge you for tax, but i guess here are a lot of possibilities here.

author: JamesP
author_rank: Newbie
timestamp: January 13, 2018, 02:58:22 pm
content: I see. Are all the prices on digikey with or without tax? Because i dont intend to atleast start selling at a capacity where i need to pay taxes (yet)+ i dont even have a company
Questions regarding solder paste dispension, cleaning flux residue - Page 1
Forum section: electronics / beginners

author: soFPG
author_rank: Frequent Contributor
timestamp: December 14, 2019, 09:50:06 pm
content: Hello forum,I just finished the building of my own reflow oven this week (based on Controleo3).I don't have stencils for my PCBs so I had to distribute the solder paste manually with a toothpick for my first project. Thisa) took a long time andb) is difficult to do for TQFP and similar footprints.So I basically dispersed solder paste all over the pins.I put the PCB in the oven - SMD caps looked nice after reflow but there were a lot of solder balls floating around the TQFP IC. Because this probably leads to shorted pins in the future I drenched everything in flux and manually resoldered the TQFP package with my soldering iron to remove the tiny solder balls and also to make sure that every pins is connected properly.After that my PCB looked really ugly because of all the flux (I want my PCBs to look nice). I then put some isoprob. alcohol on a Q-tip and rubbed the flux away which didn't work as well as I hoped.Any tips on how to avoid the tiny solder balls after reflow and how to properly clean a PCB from flux / dirt (I have seen some Youtubers using ultra sonic cleaning stations but I don't know if they are expensive or not or which model they are using at all?).Thanks so much
Quick Altium Resistor Simulation Question - Page 1
Forum section: electronics / beginners

author: TheAdmiralty
author_rank: Contributor
timestamp: December 24, 2016, 12:23:07 am
content: Evening, everyone!Got a basic question for you guys. I'm getting used to Altium right now - picked up a student license while I still can, and am trying to get the most out of it.I'm just building up a component library for a project right now, and I need a Bourns resistor pack; the footprint and symbol are trivial, but I'm having trouble figuring out how to attach a SPICE model to it. I want to have four parts of the component so that the resistor symbols can be placed separately; how exactly do you map pins to individual parts of a component? I'm using this little subcircuit:Code:.subckt RPACK8I 1 2 3 4 5 6 7 8+ params: Value=10kR1 1 2 {Value}R2 3 4 {Value}R3 5 6 {Value}R4 7 8 {Value}.ends...which I thought would work fine, but it's giving me "Could not map Pin <3 through 7>" in the netlist preview. It's fine as a single part, but that'd be a pain in the ass to drop all four resistors in a single block on the schematic. I'm sure I'm missing something really simple here, but Altium is a lot to take in all at once; anyone care to point it out?Much appreciated!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 24, 2016, 01:26:00 am
content: SPICE models are assigned per-symbol, not per-physical-component. Use the regular resistor. Then check that each part is pinned correctly (there's a little [<<] [>>] button below the pin assignment box to check each part).Tim

author: TheAdmiralty
author_rank: Contributor
timestamp: December 24, 2016, 03:24:18 am
content: Yep, didn't realize that. I was under the impression that the netlist template's "@DESIGNATOR %1 %2 @VALUE" indicated that everything was at the package level, and that I'd at least need eight modeled pins for an 8-pin device. Or something. I've been staring at a combination of Altium, LTSpice, some 3D modeling programs, and Mouser for the last ten hours and they're all starting to blur together at this point. Learn something every day.Working great, now. Thanks!
Quick COB question - Page 1
Forum section: electronics / beginners

author: DCooper
author_rank: Newbie
timestamp: April 20, 2021, 08:50:09 pm
content: Hello! I have just completed a single COB light build and unfortunately I ended up damaging part of the COB. When mounting it into a fixture my screwdriver slipped and touched the COB, and now there is a dark line across the COB which will not light up. The line is approximately 1/8 of the COB. So to my question :Before the damage was done, the COB drew about 50V and 1 amp. Now it draws 50V and .8 amp. So should I turn down the voltage or the current to compensate for the leds that are no longer part of the circuit? So I dont overdrive the rest of them? Or how does this work? I have a Meanwell HLG psu where i can adjust both voltage and current.The COB in question : Luminus CXM-22-35The PSU : HLG-60H-54A

author: thm_w
author_rank: Super Contributor
timestamp: April 20, 2021, 10:25:44 pm
content: Thedatasheetmax current is actually 3.5A, but what you can safely set it to depends on your cooling capability.If you have good cooling, there is no need to adjust anything. Do you have a thermocouple or IR temperature meter you can monitor it with?If you wanted to be safe and run the LEDs at the same individual current as prior, then you'd adjust current limit down to 1A * 7/8 = 0.88APSU can be set to max (54V).

author: DCooper
author_rank: Newbie
timestamp: April 21, 2021, 06:29:36 am
content: Thanks for answering!I have ordered a thermocouple but not received it yet. What would be a safe temperature range do you think? The cooling is passive, but has quite a lot of mass.So if I understand this correctly; even if theoretically only half the cob worked, I should still keep the voltage the same (at manufacturers recommended spec) and only adjust current?

author: james_s
author_rank: Super Contributor
timestamp: April 21, 2021, 07:25:19 am
content: LEDs are current driven, you don't set the voltage, you set the current. Driven at the correct current, the voltage automatically goes to whatever is needed to maintain the set current, within the compliance range of the power supply.

author: thm_w
author_rank: Super Contributor
timestamp: April 21, 2021, 09:11:09 pm
content: Quote from: DCooper on April 21, 2021, 06:29:36 amRecommended operating Tj is 85C.Thermal resistance is ~0.37 C/W. So a case temp of around 70C or less would be ideal at 50W.They have some heatsinks here that might give an idea:https://www.led-heatsink.com/content/files/PDFs/productPdfs/MTX/Overview/Luminus_LED_cooler_overview.pdf

author: DCooper
author_rank: Newbie
timestamp: April 22, 2021, 08:21:05 pm
content: Thanks for all the help!
quick connect vs faston - Page 1
Forum section: electronics / beginners

author: pope
author_rank: Frequent Contributor
timestamp: February 23, 2024, 01:47:52 pm
content: Can someone explain me the difference please?Mouser seem to have both options on their search tool when choosing IEC inlets.

author: schmitt trigger
author_rank: Super Contributor
timestamp: February 23, 2024, 02:21:12 pm
content: As far as I can tell: Faston itself is a quick-disconnect terminal, but the name is or was a Trademark. But it is ubiquitous such that it has become a synonym.It is now part of TE Connectivity. TE is a corporation which has acquired many smaller companies, and acquired the Faston product line and its name.

author: pope
author_rank: Frequent Contributor
timestamp: February 23, 2024, 02:36:57 pm
content: So, it's the same thing really, isn't it?

author: TimFox
author_rank: Super Contributor
timestamp: February 23, 2024, 04:06:09 pm
content: MartellTMis a trademark for a brand of cognac.Cognac is a regulated term for a type of brandy.Brandy is a term for a type of liquor.

author: pope
author_rank: Frequent Contributor
timestamp: February 23, 2024, 10:14:23 pm
content: I'll take it as a yes.

author: TimFox
author_rank: Super Contributor
timestamp: February 23, 2024, 10:34:19 pm
content: Quote from: pope on February 23, 2024, 10:14:23 pmNo.There are other forms of “quick connect” connectors that differ from FastonTMdevices.One must be careful in technical language usage.

author: pope
author_rank: Frequent Contributor
timestamp: February 24, 2024, 09:10:52 am
content: OK, then I'll take it as a "perhaps" I guess....

author: Terry Bites
author_rank: Super Contributor
timestamp: February 24, 2024, 09:37:52 am
content: Personally I prefer a Janneau armanac for relaible disconnection.

author: TimFox
author_rank: Super Contributor
timestamp: February 24, 2024, 03:32:42 pm
content: Armagnac is more reliable.
Quick Hypothetical for OB5269CP PWM Controller - Page 1
Forum section: electronics / beginners

author: OpenCircuit
author_rank: Regular Contributor
timestamp: February 01, 2020, 09:43:36 pm
content: https://www.promelec.ru/pdf/OB5269.pdfIf I supply 5v to VDD (6) and ground (5) I should be able to detect a signal of about 32Hz to 22KHZ on the gate? Assuming controller is functioning properly.
Quick question about AC-AC adapter voltage - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: September 14, 2019, 01:02:08 am
content: Hello,I have four AC-AC adapters here. One didn't work, so I decided to check the voltages on all 4. I used my multimeter on AC Volts mode, definitely not DC.One is dead completely. (0v)One is labeled 9v but the meter says 12v.Two are labeled 12v but the meter says 16v.Is this a problem or is this normal?I know often older (80s/90s) DC power supplies put out a couple volts above what the label says.Like for a device that wants 12VAC, I would think I should use my "9v" adapter that reads 12v on the meter, instead of either of my AC adapters which read 16v?

author: mariush
author_rank: Super Contributor
timestamp: September 14, 2019, 01:18:45 am
content: Your multimeter doesn't put a load on the power supply.Go to some car / motorbike parts store and get a cheap halogen/tungsten/anything working on 12v AC lightbulb (should be less than 1-2$) and use the lightbulb as a load and measure voltage at same time with your multimeter.

author: forrestc
author_rank: Unknown
timestamp: September 14, 2019, 01:24:47 am
content: Quote from: Mp3 on September 14, 2019, 01:02:08 amMost unregulated wall-warts (AC or DC) are rated for both voltage and current. Generally they will read high unless you are drawing the rated current. For instance, a 9V@300mA wall transformer will read high until around 300mA is drawn from it.So it's completely normal. One other trap for new electronics people is that if you decide to use one of those AC power transformers with a diode rectifier and a capacitor to make DC, you'll find that not only is the voltage from the 9V transformer going to be high due to the 12V 'unloaded' voltage, but you'll also end up charging the capacitor up to the peak AC voltage which will even be higher.

author: Mp3
author_rank: Frequent Contributor
timestamp: September 14, 2019, 01:34:17 am
content: Thanks to all for the helpful responses. This is what i had hoped to find out. When i googled i just got answers about measure mains voltage, so i appreciate it.
[solved] Question about audio attenuation calculations in decibels & linear %. - Page 1
Forum section: electronics / beginners

author: BrianHG
author_rank: Super Contributor
timestamp: August 03, 2022, 07:08:15 pm
content: Quick question about audio attenuation calculations in decibels & linear %.Ok, I know how to calculate the step db value for the step size of a DAC, example:8 bit dac: 20*log( 1/255) = -48.1 db per step.16 bit dac: 20*log( 1/65535) = -96.3 db per step.Question: How do I calculate the reverse, I wish to provide an attenuation db and get a factor output from 1 to 0?IE:-0db in, 1v out.-48db in, 0.00392v out.-99999db in, 0v out.

author: BrianHG
author_rank: Super Contributor
timestamp: August 03, 2022, 07:20:07 pm
content: Ok, I think I got it:10^(-db/20).For example:10^(-48.1/20) = 0.00393

author: xrunner
author_rank: Super Contributor
timestamp: August 03, 2022, 07:21:13 pm
content: 20*log(1/255) = -48.1same as20*log(.00392) = 48.1so.00392 = 10 ^ (48.1/20)orfactor = 10^(dB/20)so example you want -3 dBfactor = 10^(-3/20)factor = 0.707you want -20 dBfactor = 10^(-20/20)Edit:yea you got it.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 03, 2022, 07:24:57 pm
content: The inverse function for the logarithm function is the exponential function.Or, if you only need the value, search for online converters from dBV to V:e.g.https://www.antennas.ca/calc_db_volts.htmThe V at the end tells the decibels were calculated assuming 1V corresponds to 0dB, thus the dBV name.

author: BrianHG
author_rank: Super Contributor
timestamp: August 03, 2022, 07:29:05 pm
content: Quote from: RoGeorge on August 03, 2022, 07:24:57 pmI needed the formula, not an online calculator so I can create an FPGA/MCU firmware which needs to calculate a digital audio based volume control output with a volumetric decibel control.IE, desired -db volume in, dac data multiplier/divider gain out.
Quick Question About Function Generator Use - Page 1
Forum section: electronics / beginners

author: mart1n
author_rank: Contributor
timestamp: December 16, 2017, 07:14:42 am
content: I'm experimenting with RC low pass and high pass filters and had a quick question.Is it OK to combine the two channels from my function generator into one test circuit?For instance if I have a low pass filter, could I input one FG channel with a high frequency signal and a 2nd FG channel with a low frequency signal?I know that might seem like a dumb question, but I just wanted to make sure it was safe, wouldn't damage the FG, etc.Would I need a BNC T adapter? Or can I just add both channels to different parts of the power/ground rails on my breadboard?Thanks!

author: David Hess
author_rank: Super Contributor
timestamp: December 16, 2017, 03:07:19 pm
content: Both inputs can be used to drive the same circuit without limitations if they see the termination they are expecting.If both channels are connected directly together, then the peak current each channel will see can be doubled as with a bridged amplifier which a good design should handle without problems but who knows? Doing this also presents an impedance mismatch depending on the exact configuration which will be a problem at high frequencies. A resistive divider/combiner solves this problem and presents the proper impedance at all ports but introduces 6dB of loss which may be unacceptable. Over a limited frequency range, an RF splitter/combiner could be used instead to avoid the power loss.If both signals need to be combined without limitations, then a small summing amplifier could be used.
Quick question about making a custom PWM fan cable for Dell PC - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: September 11, 2018, 10:54:34 am
content: It seems that most or all dell computers use a 5 pin custom connector for fans, but it's easy to wire a 4 pin PWM fan to the Dell connector.I'm looking to replace all the fans in a Dell with PWM fans and a PWM controller. This controller sends back one 4 pin PWM to the motherboard for control.The Dell motherboard has two fan connectors i would need to populate to not get a fan error. Is there any reason it wouldn't work if I cut off the 4 pin fan connector and solder the two wires for PWM control to both the motherboard fan connectors?I wanted to check and see if there was any reason this wouldn't work before i buy anything and cut off any fan connector.Thank you all!

author: macboy
author_rank: Super Contributor
timestamp: September 11, 2018, 02:32:24 pm
content: Quote from: Mp3 on September 11, 2018, 10:54:34 amThe only thing you should need to connect back to the second fan connector is the RPM signal. This can be the same signal as sent to the first one, or the signal from another fan. Just as long as the computer thinks the fan is spinning fast enough, you'll be OK.On a typical 4-pin PWM fan, this is the Pin 3 and should be a green wire. You'll need to map that to the appropriate spot on the Dell connector which I am not familiar with.
Quick question about RC and LC pass filters - Page 1
Forum section: electronics / beginners

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: December 07, 2016, 07:02:00 pm
content: Hi there,When calculating the values for these simple circuits, should one take into account the resistance and impedance of the speaker itself as well as the components that will be added to achieve a certain cut-off frequency?

author: tatus1969
author_rank: Super Contributor
timestamp: December 07, 2016, 09:12:08 pm
content: as most drivers are designed to be driven by the low ohmic output voltage of an amplifier, i would take the complex impedance curve of them into account when designing a filter. my high end 2way speakers have a crossover board with literally dozens of parts.

author: danadak
author_rank: Super Contributor
timestamp: December 08, 2016, 12:44:48 am
content: The load for sure will effect circuit response, unless you filter in the signalpath, buffer, and drive speaker with buffer output. Of course the latterrequires amp for each driven component.Regards, Dana.

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: December 08, 2016, 04:48:28 am
content: Ok; I'm obviously not making the simplicity of my knowledge and the circuit clear enough. I'm a dumbass, so I have posted in the beginner fourm.Given an RC high-pass filter supplying an 8 ohm speaker, should I account for the fact that the speaker itself has 8 ohms of resistance in addition to the resistor I would normally use with the capacitor in order to calculate cut-off frequency?I assume the same will be true of impedance, in a low-pass filter.To put it another way: when calculating the values for resistor and capacitor in a simple RC high-pass filter, should I cater for the fact that the speaker has 8ohms resistance as well? Ie, the resister should be 8 ohms less, if it matters.Alternatively, in an LC low-lass circuit, should I measure and then account for the speaker's impedance when calculating what resistor and inductor will be required for a given cut-off?

author: tatus1969
author_rank: Super Contributor
timestamp: December 08, 2016, 06:25:48 am
content: can you measure their impedances? means, do you have a lcr meter?
Quick question about shorting jumper pins - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: January 27, 2019, 12:16:05 pm
content: Hey everyone.I have a 2x6 row of pins and two consecutive pairs need to be jumped like soII----II----I dont have enough jumpers around to accomplish this and it is only needed for one task and then the jumper will be removed.Since the two jumper pairs are touching each other. Would it be safe to roll up a tiny ball of aluminum foil and put it between those pins to short all 4 out?or is it risky to not only jump them as pairs? (this is an IDE hard drive)

author: mariush
author_rank: Super Contributor
timestamp: January 27, 2019, 12:24:17 pm
content: No, without knowing exactly where those pins go, you can't.

author: soldar
author_rank: Super Contributor
timestamp: January 27, 2019, 12:24:53 pm
content: You don't have two jumpers? Do you have one? None?At any rate, you could make the jumper with a bit of cardboard with aluminum foil glued to the side.I would not recommend shorting all four pins. Just in case.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: January 27, 2019, 12:29:07 pm
content: You can use a piece of bare copper wire and wrap it a few times around the pins you want to connect while the power is off.This is a lot easier if you have some spare 0.1" header pins in 2's as a mold.
Quick question... can I make the following assumption? - Page 1
Forum section: electronics / beginners

author: ilbs
author_rank: Contributor
timestamp: October 17, 2013, 01:49:14 am
content: Hello,I could totally wrong about this, so guys go easy on me if I am completely out in left field.But, lately by experimenting with op amps I have come across some observations and I would like to know if what I observed is right. The configuration is where the inverting inputis connected with the typical rf and ra resistors and the non invertinginput is connected with the typical voltage divider formed by r1 and r2 resistors.So, when dealing with traditional op amps in this type of configuration, canone make the following statements:QuotePlease note these statements are in reference to op amp configurations where we have an input voltageramp at one of the two op amp inputs while the other input is at a steady voltage.Thanks for your feedback!

author: w2aew
author_rank: Super Contributor
timestamp: October 17, 2013, 02:46:16 am
content: In general, yes, those statements are true - given the assumption that the op amp is sitting in an active state where the output isn't jammed to its min or max value, the inputs are well within their common mode range, and the negative feedback loop is closed properly such that the voltage difference between the inverting and non-inverting inputs is effectively zero.Have you watched my video on a no-nonsense way of understanding the operation of most op amp circuits?

author: ilbs
author_rank: Contributor
timestamp: October 17, 2013, 03:01:14 am
content: Hi w2aew,yes I did .... thanks for a very insightful and usefulvideo.and thanks for replying !
Quick Question:  How does my electric kettle know when to turn off? - Page 1
Forum section: electronics / beginners

author: darrenb
author_rank: Contributor
timestamp: May 04, 2012, 09:36:50 pm
content: Hi,Just wondering how my electric kettle knows when the water has boiled and to turn off? What kind of sensor or mechanism does it use?Here in Australia it's known as a kettle but it may be known as a jug or water boiler or something else elsewhere. Anyway you put some water in it, plug it in to the wall turn it on and it boils water. How the ? does it sense when the water has boiled and know to turn itself off?

author: IanB
author_rank: Super Contributor
timestamp: May 04, 2012, 09:39:08 pm
content: When the water boils steam flows along a tube and heats up a temperature sensor like a bimetallic strip, which then trips off the power.(If the tube gets clogged up with scale the steam may not reach the sensor and the kettle will gradually take longer and longer to switch off.)

author: djsb
author_rank: Super Contributor
timestamp: May 04, 2012, 09:46:26 pm
content: The bimetallic strip is explained herehttp://en.wikipedia.org/wiki/Bimetallic_stripDavid.

author: pickle9000
author_rank: Super Contributor
timestamp: May 04, 2012, 10:13:57 pm
content: As with most appliances it must also have a failsafe system. That is typically a thermal fuse (a fuse set to blow at a specific temperature). The contact points can fuse together making it so that the heating element never turns off. In this case the thermal fuse will blow after the kettle has boiled dry. The boiling water keeps the fuse temperature below the trip point, when dry the temp rises it blows and your house has not burnt down.Thermal fuses are often crimped into place because soldering them will kill them....mike

author: darrenb
author_rank: Contributor
timestamp: May 04, 2012, 10:20:01 pm
content: Thank you.
Quick question on BCI group number - Page 1
Forum section: electronics / beginners

author: Rick Law
author_rank: Super Contributor
timestamp: June 14, 2020, 04:57:40 pm
content: Friends,Is the attach photo a 24Ror a 24 (without the R)?24 is not my size, I just need tofigure out R or no-R. Mine is size 51 but my battery has +/- posts that match the one in the photo. So, if this one is an "R", I know mine needs an "R" (or not)Some on the web say "For Honda Civics 2001, the battery is 51R". On battery store sites, some store say a 51 fits, some say 51 doesn't fit and I need 51R instead, and one shows either one fits.I know currently the battery cables attached doesn't has any slack at all -- certainly not long enough to reach if I need to rotate the battery around. May be the stock battery cable in the car has been fixed/replaced with a shorter one leaving no room for rotation... So it is either 51 or 51R but not both fits.To avoid re-stock fee, I need to know 51 or 51R.Thanks!

author: floobydust
author_rank: Super Contributor
timestamp: June 15, 2020, 12:38:08 am
content: BCI size code is "51" and "R" means reversed polarity (post location), like "F" Ford versions. So a 24 with reversed terminals is commonly called 24F or lesser so 24R.Honda uses the tiniest car battery available. I believe you have "51" no-R in your pic. Later Civics used 51R I think because they moved the battery from the firewall to the front corner, and flipped it.

author: Renate
author_rank: Super Contributor
timestamp: June 15, 2020, 10:28:09 pm
content: I've known about R and no R, but you got me wondering about my battery, a 78N.Apparently some of the suffixes are more arbitrary/optional/capacity.A 78N is supposed to have more capacity than a 78.I went to the Battery Council's website.https://batterycouncil.org/store/ListProducts.aspx?catid=756040We just need someone to pony up $500 for the manual.Until then, I'll just stick with my favorite, GC2, 6 Volt, "golf cart" batteries.
Quick Question on MOSFET power losses - Page 1
Forum section: electronics / beginners

author: augustol
author_rank: Contributor
timestamp: October 16, 2021, 07:08:12 pm
content: Hi, everyone,I was reading an "Application Note" from the International Rectifer and studying it yesterday. I like to do a first read along the whatever-I-am-studying and than come back re-reading it paying more attention to finer detail.So I was re-reading it today and taking a closer look the formulas than I noticed some terms in the power conduction losses that I couldn't identify.Pcond=(RDS(on)/RL).P0The P0term could be PO(for power output maybe?) Since the note doesn't explain anything about the formulas, I suppose it's something dumb and basic, but it's new to me.So, the RLand P0terms are reffering to what?Here's the link to the Application Note if anyone want to check it (page 6):https://www.infineon.com/dgdl/an-1071.pdf?fileId=5546d462533600a40153559538eb0ff1

author: Manul
author_rank: Super Contributor
timestamp: October 16, 2021, 08:15:52 pm
content: RLshould be load resistance and POshould be output power (power dissipated in RL).

author: magic
author_rank: Super Contributor
timestamp: October 16, 2021, 08:38:15 pm
content: P=IRMS²·RDS(on), simple as that.Your formula works exactly when POis the total power output of the PSU and RLis the combined resistance of the load and MOSFET. Do the math (I²·R) and see yourself. If RDS(on) is much less than load resistance, then the approximation given above also gets close enough.

author: Picuino
author_rank: Super Contributor
timestamp: October 16, 2021, 09:22:50 pm
content: MOSFET power losses and how they affect power-supply efficiencyEdit:Basic Concepts of Linear Regulator and Switching Mode Power Supplies
quick question what does the 220 mean in a TO 220 package - Page 1
Forum section: electronics / beginners

author: generic_username
author_rank: Regular Contributor
timestamp: December 04, 2015, 09:19:32 am
content: As the title says I can't seem to find any Information for what the number in a TO package means.cheers.

author: Gyro
author_rank: Super Contributor
timestamp: December 04, 2015, 09:29:22 am
content: Nothing exciting I'm afraid. It's just its numerical designation under the JEDEC international package standard... Google JEDEC.

author: coppice
author_rank: Super Contributor
timestamp: December 04, 2015, 09:36:26 am
content: TO == Transistor Outline220 == The one that came after 219 at the JEDEC meetings.TO3, TO5, TO18, TO220. We remember the golden oldies, and forget all the rest.

author: Gyro
author_rank: Super Contributor
timestamp: December 04, 2015, 09:47:55 am
content: Err... TO92, SO, SOT etc.?Edit: But yes, we didn't see or remember all the ones in between.

author: GNU_Ninja
author_rank: Regular Contributor
timestamp: December 04, 2015, 09:53:17 am
content: TO archive:https://www.jedec.org/standards-documents/focus/registered-outlines-jep95/transistor-outlines-archive

author: generic_username
author_rank: Regular Contributor
timestamp: December 04, 2015, 09:55:19 am
content: wow big thanks to everyone, didn't know that there's no meaning for that naming

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 04, 2015, 11:45:32 am
content: There are some crosses, like:TO-3 superseded(?) by TO-204.TO-220 royally sucks; TO-220AB is more familiar.TO-5 is the really old (large can) one, but it's potted; TO-39 is actually the welded can version. And TO-99 is the multipin version.TO-72 is the four pin TO-18 (which are potted as well, or at least usually).Almost every time someone says "2Nxxxx" and it's a TO-18 part, they're being dumb. No one buys 2N2222s anymore, nor should they. PN2222 is the plastic (TO-92) variety, but even better is 2N3904 or 2N4401 (a much better spec'd general purpose BJT).Or in reference to avalanche pulse generators, 2N2369 is a pretty awful choice, but the PN (TO-92) or MMBT (TO-236 aka SOT-23) variant is pretty good.Tim
Quick way to reverse engineer modbus? - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: February 13, 2024, 06:13:26 am
content: Hi,I should say up front that I'm not a programmer.I just bought a new inverter (Goodwe SBP G2) and I need to control it with modbus, I've got the inverter installed and I have a working connection using a waveshare modbus TCP to RTU converter.So I bought this inverter because the modbus was already reversed. The vendor has changed it and won't provide a document.So I'm using node-red, the previous modbus implementation would provide the serial number when you read 0x0200 I figured out that that has changed to 0x07D0.So does anyone have a way to quickly enumerate all the addresses, so I can use the SolarGo app to change something and search modbus for changed values?Thanks.Richard

author: RoGeorge
author_rank: Super Contributor
timestamp: February 13, 2024, 06:42:19 am
content: I would installwireshark, to sniff the modbus TCP packets. Then use the modbus device together with its own application (from the provider), to learn the must-have coils and registers addresses, and their values.AFAIK modbus can not be interrogated about its register addresses, so you can only sniff the exchanged data and try to deduce which does what.Before anything else, contact the manufacturer and kindly ask them for the programming manual, or for the modbus registers directly. Maybe they'll give you the info.

author: rthorntn
author_rank: Frequent Contributor
timestamp: February 13, 2024, 06:47:38 am
content: Thanks, the manufacturer refused to provide the info.Unfortunately the SolarGo app communicates with the inverter over WiFi, not through my RS485 TCP adapter.

author: RoGeorge
author_rank: Super Contributor
timestamp: February 13, 2024, 07:04:25 am
content: Wireshark can sniff any network card, including wireless ones. Install a solar Go app on a PC/laptop that has a connection to the wireless network, so you can install Wireshark on the same machine where the Solar Go is running, and sniff the packets.If not, try to sniff from the air the wireless packets between the Android phone and the RTU device. Preferably sniff them from the phone/tablet (e.g.https://stackoverflow.com/questions/9555403/capturing-mobile-phone-traffic-on-wireshark). Should be possible to sniff from the air to, though might be more difficult, depending on the encryption type used by the wireless.What device/network layout do you use now, to control the RTU?

author: voltsandjolts
author_rank: Unknown
timestamp: February 13, 2024, 07:55:18 am
content: A starting point perhaps...

author: Doctorandus_P
author_rank: Super Contributor
timestamp: February 13, 2024, 10:56:11 am
content: If they refuse to give decent usermanual (including all mosbus register names and usage) then return the inverter and buy another one which does have this info.
Quick/dirty adjustable PSU from 24V SMPS - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 04, 2019, 06:42:08 pm
content: I have a nice 24V SMPS from a printer, that I want to use to power a pass BJT supply, for as wide a range as possible. I only want a few hundred milliamps, just for little quick breadboard use, and it will fit on a 5x7cm pref-board.Should I heatsink a 2n3055 for say 0.5A at say 22V ?So I could use a TL431 or overkill LM317 to drive the BJT. Should I use 2N3055 or the PNP version ?And should I have a small resistor, from the regulator output, to the BJT base ? I assume I should put a small cap on the base. So that would make an RC filter.

author: Gyro
author_rank: Super Contributor
timestamp: April 04, 2019, 07:45:13 pm
content: Quote from: lordvader88 on April 04, 2019, 06:42:08 pmWhich is it?2V drop at 0.5A is 1W, a bare TO3 pkg is probably sufficient.EDIT: Plenty of simple options...https://duckduckgo.com/?q=2n3055+regulator&atb=v145-4__&iax=images&ia=images

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 04, 2019, 10:03:20 pm
content: Oh right, it's Vce*Ic. So 10W if I had 4V@0.5A output with npn. Either way that won't matter much, I can put an old CPU heatsink on it if needed.

author: Zero999
author_rank: Super Contributor
timestamp: April 05, 2019, 10:52:00 am
content: Quote from: Gyro on April 04, 2019, 07:45:13 pmI thought he wanted it to be adjustable. The maximum power dissipation depends on the current, at the minimum output voltage.The LM317 alone will probably do, as long as it's on a big heat sink.

author: Gyro
author_rank: Super Contributor
timestamp: April 05, 2019, 11:38:13 am
content: That's why I highlighted the two conflicting passages and asked the question!

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 05, 2019, 03:44:06 pm
content: Yes adjustable, and I know the LM317 could do it, but with the 2n3055/pnp for most little stuff, I'm guessing it's metal can would cool it enough.Why is there usually a resistor feeding into the base on cases like this, is it related to some leakage current ? Or to slow 'in-rush' from the driver device ?

author: iMo
author_rank: Super Contributor
timestamp: April 05, 2019, 04:21:24 pm
content: LM317 includes a voltage reference, overcurrent and chip temperature control.When planning with your 3055 as the pass transistor you have to add the circuitry.The another version could be a beefy metal transistor on top of the 317, but again you need a circuitry at least for the current limit.And 10W is too much for 317 as well as for 3055 without a larger heatsink (or smaller one with an active cooling).
Quick/Madell/LRP QK202D Hand piece replacement - Page 1
Forum section: electronics / beginners

author: The Knuckle
author_rank: Newbie
timestamp: September 10, 2019, 11:05:39 pm
content: Hi Guys,Well I needed a better soldering station or an Actual solder station. Anyways, came across a Quick 202d for $30 without a hand piece. I've found a OEM Quick Brand handpiece/iron for about $60 shipped, but was curious if there are other compatible irons, or can say, a JBC C245 be modified to work by swapping the plug on the iron or power supply? I ask because the JBC is about the same price.Thanks for any help!
quiescent current of opamp - Page 1
Forum section: electronics / beginners

author: Jwillis
author_rank: Super Contributor
timestamp: September 28, 2019, 04:04:14 am
content: On the OPA445 the quiescent current is typically ±4.2 mA . That means that the positive and negative will draw ±4.2mA with no load. How do I calculate the current at the supply pins under full load? Or am I over thinking this?https://www.ti.com/lit/ds/symlink/opa445.pdf

author: ledtester
author_rank: Super Contributor
timestamp: September 28, 2019, 05:16:32 am
content: Starting with I_Q, just add the output current to the V+ current (if the output is sourcing current) or the V- current (if the output is sinking current).So the max current through either the V+ or V- supply pin is i_Q + your max output current.See also:https://electronics.stackexchange.com/a/31032/95488

author: Jwillis
author_rank: Super Contributor
timestamp: September 28, 2019, 07:42:03 am
content: Wow! That easy? I thought it would be more complex. Just wanted to make sure a 1 amp -15V regulator at the negative side would be enough without a pass transistor.
R-2R ladder and pwm - Page 1
Forum section: electronics / beginners

author: cosminnci
author_rank: Regular Contributor
timestamp: June 10, 2013, 07:59:54 am
content: Hi,I seen a bench power supply and for driving the output it uses 5 bit pwm and 7 bit r-2r ladder operated by 7 digital pins of microcontroller, the explication for using this is faster control of the output.I understand that the pwm outputs pulses which filtered can be converted to dc,and that the r-2r ladder offers a output voltage in steps and in powers of 2but how can the pwm and r-2r be interconnected to create a 12 bit dac ?regards,Cosmin

author: daveatol
author_rank: Regular Contributor
timestamp: June 10, 2013, 08:59:23 am
content: The R-2R ladder would likely be the MS bits and the PWM fed through the LSb. You obviously understand how the R-2R works. If we have the LSb high, then it contributes 1/64 Vref to the output. If the LSb is low, then it doesn't. If we have the LSb high for 50% of the time and low the remainder, then it contributes 1/64*0.50, which is the same as having an additional bit below the LSb high. If the LSb is high for 25% of the time, then it contributes 1/64*0.25, which is the same another extra bit - i.e. two additional bits below the LSb, with the lowest one high.Following this for 75% high time, the two additional bits would be '11', or 62.5% high time gives '101' (all below the LSb), etc.

author: cosminnci
author_rank: Regular Contributor
timestamp: June 10, 2013, 09:59:20 am
content: the part I don`t understand how do we feed the pwm as LSB.would it be connected in series with the r2r ladder ?

author: daveatol
author_rank: Regular Contributor
timestamp: June 10, 2013, 10:16:10 am
content: The PWM is fed into the resistor corresponding to the least significant bit of the ladder.

author: daveatol
author_rank: Regular Contributor
timestamp: June 10, 2013, 10:22:21 am
content: This schematic shows where the 6 most significant bits go, and where the PWM is goes. (there will also be a capacitor connected to Vout to smooth the signal)(ref: image derived from image on google images)

author: cosminnci
author_rank: Regular Contributor
timestamp: June 10, 2013, 10:26:23 am
content: Thank you, this is clear now.