hybridfree/eevblog-posts huggingface dataset:
How to correctly meaure an LDR? - Page 1
Forum section: electronics / beginners

author: orbiter
author_rank: Frequent Contributor
timestamp: February 22, 2011, 11:39:43 am
content: Hiya fellas,Got some new light dependant resistors today in a variety type pack, so they're not rated, so... How do I measure them correctly please?Is it in total darkness, shade... Or some sort of average?Thanks guysregardsorb

author: PeterG
author_rank: Frequent Contributor
timestamp: February 22, 2011, 12:42:36 pm
content: Are there any markings on it at all?This webpage may be a good starting point.http://www.technologystudent.com/elec1/ldr1.htmRegards

author: orbiter
author_rank: Frequent Contributor
timestamp: February 22, 2011, 01:33:50 pm
content: Quote from: Darkman1969 on February 22, 2011, 12:42:36 pmNo mate, I've checked all of them. No markings at allThey're just the very basic type, similar toThis LDRand are measuring a dark resistance of around 500k, now this could be pretty close I guess, but I'm not sure if just putting a rag over the end of them, then measuring the resistance is an efficient way of doing it?regardsorb

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 24, 2011, 08:46:05 pm
content: Put it into a box with a LED and a reference sensor. Vary the LED brightness and note the changes.

author: orbiter
author_rank: Frequent Contributor
timestamp: February 24, 2011, 09:21:30 pm
content: Quote from: NiHaoMike on February 24, 2011, 08:46:05 pmThanks Mike. Is that a legitimate & accurate way of measuring them?Regardsorb
How to count individual pulses in a repetitive train of pulse packets - Page 1
Forum section: electronics / beginners

author: qqwasder
author_rank: Newbie
timestamp: February 11, 2018, 07:38:18 pm
content: Using the manual, I can't seem to figure out how to solve the following:- The signal consists of repeated packets of pulses with about 50ms between packets- Each packet contains about 1000 1us pulses- The main information is encoded in the number of pulses in each packet (which I am trying to determine)While I can easily display an individual pulse packet and its included 1us pulses, I can't figure out how to configure my Rigol 1054Z to consistently count the individual pulses in a in a given packet. If I capture a packet, then adjust the time base to show, say, 5 1us pulses, the counter shows "5 pulses". as I lengthen the time base the displayed waveform shows more and more 1us pulses and the counter increases accordingly. But as I continue to increase the time base, the counter seems to top out at 528 pulses. If I lengthen the timebase 1 more time, the counter drops to 412. If I display the entire packet (its just a blur by this time), the counter shows "108 Pulses". It seems like there an upper limit to number of pulses the scope can count (or a minimum interval between pulses). Any insight would be appreciated.

author: mcinque
author_rank: Unknown
timestamp: February 11, 2018, 09:06:37 pm
content: I fear that the rigol can't do what a real counter do, AFAIK it's a software feature that counts only what's on the screen "looking" a the waveform and it's not very precise. It counts well only when there are few pulses with a well defined shape. Maybe I'm wrong, but I think that in your case it should be mandatory to use a proper counter.

author: David Hess
author_rank: Super Contributor
timestamp: February 12, 2018, 05:12:34 am
content: My understanding is that with the exception of FFTs, the Rigol only makes measurements of the display record which limits it to something like a 1200 point record length so pulse counting will be very limited.
How to create a 1:1 adapter between TSOP48 THT layout and SlimStack / Panasonic  - Page 1
Forum section: electronics / beginners

author: cobramostar
author_rank: Contributor
timestamp: May 13, 2025, 09:00:59 pm
content: Hi all,I'm designing a simple adapter PCB in KiCad and would appreciate some advice on how to approach the mechanical and electrical design.I want to create a 1:1 pinout adapter that:Has a TSOP48 open-top test socket mounted on the TOP layer (e.g., TSOP48-0.5 Open Top Burn-in Socket IC354-048-D31/35P)The socket has THT pins arranged in 3 rows per side (total of 48 pins), as found in adapters like TSOP-48-0.5-OTS04 from ANDKTECHOn the BOTTOM layer, I plan to place two board-to-board connectors (e.g., Molex_SlimStack_52991-0508_2x25_P0.50mm_Vertical), mounted perpendicular (90° rotated) relative to the test socketUse case:This adapter board should connect to another PCB that has a TSOP48 flash footprint, effectively allowing the test socket to be used in place of the chip, via the connectors.Questions:What’s the best way to define a THT pad layout matching the 3-row-per-side pattern (2.54 mm column pitch, 1.27 mm row spacing)?How can I precisely position the SlimStack/P5K connectors so they align with the original flash footprint on the main board?Any tips for simulating this in the 3D viewer to validate orientation and fit?Does anyone already have a similar adapter layout or footprint to share?Thanks in advance for any advice or examples!

author: thm_w
author_rank: Super Contributor
timestamp: May 14, 2025, 12:18:02 am
content: You can search and find the footprint already exists:https://41j.com/blog/2016/10/tsop48-zif-socket-footprint/Though it has some mistakes, so be cautious to fix them.If you were creating from scratch then I'd place a through hole pad at location 0, set its ID and OD. Then make an arrayhttps://forum.kicad.info/t/footprint-pad-array/22859Then another array or copy paste at appropriate x offset of 5.08 and y offset of 0.5mm.

author: cobramostar
author_rank: Contributor
timestamp: May 14, 2025, 07:25:59 am
content: Quote from: thm_w on May 14, 2025, 12:18:02 amPins 26 and 27 appear twice.I concluded that pads 26 and 27, the large ones found in lines 62 and 63 of the .kicad_mod file, are mechanical holes used for mounting the socket. They are correctly positioned and have the proper diameter and size. However, they should not have the same numbers as the signal pins 26 and 27.Therefore, I will keep these large pads because they are useful, but I will change their numbers to 49 and 50 to prevent any conflict.Quote

author: cobramostar
author_rank: Contributor
timestamp: May 14, 2025, 08:22:30 pm
content: Quote from: thm_w on May 14, 2025, 12:18:02 amThank you very much for your help!This was all new to me, but thanks to your guidance I managed to correct the footprint manually by comparing it with the PDF. I really hope I did it right — I've never worked on something like this before. I’m attaching a picture of the result.Much appreciated!
How to create a device to power on a projector via HDMI control? - Page 1
Forum section: electronics / beginners

author: nhchmg
author_rank: Newbie
timestamp: May 05, 2025, 02:57:52 am
content: How to create a device to power on a projector via HDMI control? I’ve built a prototype where the HPD line is pulled up to VCC, the HDMI CEC line is pulled up, and other signal lines are disconnected. By sending CEC commands like 0x4 0x44 0x6c or 0x4 0x36, I can successfully power off a Mi Box 4. However, sending 0x4 0x44 0x6d, 0x6b, or 0x40 does not power on the Mi Box 4. Are additional signal lines (e.g., DDC/I2C) required for HDMI power-on functionality?Key Details:Setup:HPD pulled high (to VCC).CEC line pulled up.Other HDMI signals (TMDS, DDC, etc.) unconnected.Working Commands:0x4 0x44 0x6c (Power Off).0x4 0x36 (Standby).Non-Working Commands:0x4 0x44 0x6d (Power On).Other variants (0x6b, 0x40).Question: Why does power-on fail? Is a valid EDID/DDC connection required for CEC power-on, even if power-off works without it?Thank you in advance for your insights!

author: Doctorandus_P
author_rank: Super Contributor
timestamp: May 05, 2025, 06:13:24 am
content: According to:https://en.wikipedia.org/wiki/HDMIpin 19 of the HDMI connector is for +5V. To be able to listen to commands, and being able to turn on from external info, some part of your HDMI device must be listening, and thus powered.In the old VGA days, +5V was connected to an I2C EEPROM, so a PC could read back DDC data, even if the monitor was unpowered (I.e, the power plug is not in a wall socket).

author: nhchmg
author_rank: Newbie
timestamp: May 05, 2025, 11:19:48 am
content: Thanks for your response! Just to clarify, pin 19 is Hot Plug Detect (HPD), which is already pulled high in my setup. The device can successfully receive HDMI CEC commands from the Mi Box 4 (e.g., power-off works), but CEC power-on commands (like 0x4 0x44 0x6d) fail to wake the Mi Box4.
how to create an equivalent 3 phase load using bulb ? - Page 1
Forum section: electronics / beginners

author: vis5254
author_rank: Contributor
timestamp: March 07, 2019, 08:01:19 am
content: worry is that i dont have a three phase induction motor model in proteus software . so i wish to virtually create a 415v rated three phase induction motor by using just bulb (in star mode perhaps) . Proteus asks for voltage and resistance as input value . plz help

author: Zero999
author_rank: Super Contributor
timestamp: March 07, 2019, 01:40:13 pm
content: Please provide more information. The electrical characteristics of a motor depend on its power rating, design (e.g. a copper bar rotor will have less slip, than an aluminium one) and mechanical load.

author: rstofer
author_rank: Super Contributor
timestamp: March 07, 2019, 05:49:30 pm
content: I don't know if it matters but a real motor has an inrush current up around 6 times full load current. It declines as the motor accelerates but the rate of acceleration will be a function of inertia. Big fans take a LONG time to get up to speed and, because of this, we often use wye-delta motor starters. The motor starts up with the windings connected in a wye configuration and, after some time, the contactors charge the connection to delta.How may horsepower (or kW) are you trying to simulate?
how to create custom diode and add its netlist into Ansys circuit designer schem - Page 1
Forum section: electronics / beginners

author: Ciji
author_rank: Newbie
timestamp: July 14, 2025, 01:30:07 pm
content: I am trying to simulate a 2.45 GHz RF voltage doubler rectifier circuit in Ansys Circuit Designer (Nexxim) using HSMS-282E Schottky diodes. I previously validated the circuit in LTspice using the default diode to check rectification and now I want to replicate the same with HSMS-282E Schottky diodes in Ansys.I need help with: How to create or import a custom diode model (e.g., using .model or .subckt or using netlist from the vendor SPICE parameter values)How to add that custom diode model to a schematic in Circuit DesignerIf there’s a preferred way to simulate nonlinear rectifier circuits like this at high frequency , harmonic balance vs. transientThank you in advance for any guidance on importing the diode and setting it up correctly in Circuit Designer.
How to deal with learning plateau in electronics engineering? - Page 1
Forum section: electronics / beginners

author: shivajikobardan
author_rank: Contributor
timestamp: December 25, 2021, 05:19:37 am
content: 1) Follow a good course from a good teacher.2) Read it aloud.3) Practice the same thing multiple things to get insights. deliberate practice. I am doing a course on artificial intelligence(deals with robotics) and man I feel so hard this thing.What else can I do to overcome this learning plateau?https://drive.google.com/file/d/1fpksOvK5bLVC5C0njB-fNPgzOwj4GjqW/viewThese are the types of questions I need to deal with and where I am facing this learning plateau..

author: PixieDust
author_rank: Frequent Contributor
timestamp: December 25, 2021, 06:46:49 am
content: I can only suggest to start applying the knowledge to practical problems. Theory starts making more sense as you gain practical experience.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 25, 2021, 08:42:32 am
content: Quote from: PixieDust on December 25, 2021, 06:46:49 amExactly this, it needs to be iterative process. Learn enough theory to start making practical prototypes. Revisit theory to explain why things go like they do. Rinse and repeat.

author: rstofer
author_rank: Super Contributor
timestamp: December 25, 2021, 03:15:20 pm
content: Considering the specific nature of the exam questions, I assume the material has been covered in a class. Right after the lecture, work some of the exam questions that are related.Keep notes and perhaps a more formal journal of problems and full solutions. Just solving problems and writing things down will help with retention.Nothing in life prepares you for a class like this. Plan on spending every waking moment studying or sitting in class. This stuff isn't easy! With luck, you will have time to eat. Some days that won't work out.

author: themadhippy
author_rank: Super Contributor
timestamp: December 25, 2021, 03:41:05 pm
content: leave it alone,forget about it, go and do something else totally different,when your least expecting it something will suddenly clunk into place
How to decide a Ceramic Cap is useless - Page 1
Forum section: electronics / beginners

author: watchmaker
author_rank: Unknown
timestamp: April 10, 2025, 12:47:33 pm
content: At what point is a NOS ceramic cap unusable?For example, a 2pF NPO that measures 3.5pF (Shannon Tweezers at 10kHz)Can this be trusted in an application that calls for a 2pF cap?Or if a 1nF cap measures 700pF; can it be trusted in a 690pF application?What kind of variance in value is acceptable in analog ckts?THANKS!

author: Grandchuck
author_rank: Super Contributor
timestamp: April 10, 2025, 12:49:53 pm
content: Measuring a 2 pF capacitor with tweezers is difficult when high accuracy is needed.

author: Zero999
author_rank: Super Contributor
timestamp: April 10, 2025, 12:52:50 pm
content: It depends on the tolerance. Low value capacitors, hardly ever fail. If it reads open circuit and is not physically damaged, then it's highly likely it's good.

author: Sensorcat
author_rank: Regular Contributor
timestamp: April 11, 2025, 01:10:26 am
content: It also despends on the application of the capacitor. Two examples:Tolerance of capacitors across the power supply of ICs is usually uncritical, because it acts as a local buffer of charge for the supply. If the IC needs more current momentarily, these capacitors prevent supply voltage decrease. More capacitance than needed does no harm, and the precise amount needed is rarely calculated, with 100nF being a standard value.Tolerance of capacitors in filters and tank circuits is usually critical, because it translates to a tolerance in frequency response, the most important property of these circuits. Together with inductors and resistors, the capacitors determine the frequency response.If capacitors have very small values, like <10pF, they are typical for circuits operating at high frequencies, simply because such a small capacitance does almost nothing at, e.g. 10kHz. So it is also difficult to measure them accurately at only 10kHz. And even if you do, the result does not help much to tell something useful about the device at its intended operating frequency. 1pF@10kHz is an impedance of about 16MΩ, which means your tweezers have to measure a tiny AC current accurately (difficult), but at 10MHz, the impedance is about 16kΩ (easy).A likely reason for measuring too high on a small capacitor is parasitic capacitance of the wires or connections between DUT and instrument. Calibration is important here.

author: watchmaker
author_rank: Unknown
timestamp: April 11, 2025, 11:26:52 am
content: Thank you Sensorcat, this gets to the meat of my interest.These are the real life issues not specifically covered in first year texts (at least that I have gotten to yet).
How to design (start ) my own DDR controller. - Page 1
Forum section: electronics / beginners

author: AnuI
author_rank: Newbie
timestamp: April 26, 2018, 07:11:05 am
content: Hi everyone.I want to design my own DDR controller for my project work.I am good in verilog and will design in verilog.But i dont know how to start and how to approach this task.Anyone how had worked on DDR controller from scratch could please help me with this??I will be using Xilinx VIVADO for simulation and synthesis.Please suggest .

author: hamster_nz
author_rank: Super Contributor
timestamp: April 26, 2018, 07:35:04 am
content: Read the memory datasheet many times over.Start with the simplest design you can make work.Plan how you will verify that the design is working correctly.Test first on known-good hardware.

author: Kalvin
author_rank: Super Contributor
timestamp: April 26, 2018, 07:36:54 am
content: http://lmgtfy.com/?q=verilog+ddr

author: AnuI
author_rank: Newbie
timestamp: April 27, 2018, 05:10:53 am
content: Thanks hamster_nz.Thanks for the help.I have started reading JEDEC79E DDR specification.If i need help.. i ll post again.Thanks

author: hamster_nz
author_rank: Super Contributor
timestamp: April 27, 2018, 06:57:07 am
content: I found that the Micron datasheets have a quite straight and to the point description, rather than the more technical standards documents.

author: AnuI
author_rank: Newbie
timestamp: May 04, 2018, 05:35:11 am
content: Ok @hamster_nz.I ll look at the Micron datasheet.Thanks
Designing a (simple) 35AH lead acid battery MPPT solar charger? - Page 1
Forum section: electronics / beginners

author: abhishekkumar1902
author_rank: Regular Contributor
timestamp: September 14, 2015, 08:55:45 am
content: Hello there,I want to design a simple (butfairly good) MPPT based solar charger (similar to the tim nolan's PPT charger) for a 35AH lead acid chemistry but I have a confusion that although you can control power (power matching) using the MPPT methodology, how do you ensure safe charging of the lead acid battery i.e. how can we limit the current in the MPPT charger circuit for example which is usually required to safely charge the lead acid battery upto within 0.15C continuous current in BULK mode. Charge termination and other can be done easily by measuring the max voltage or may be some 10% of the bulk charging current but I wanted to know that how can we limit the charging current in the MPPT method if we are using the synchronous buck topology. Also wanted to know how it is done in simple buck power supplies. We can easily vary the output voltage by changing the duty cycle of the driving pulse in a buck converter but how do we control the output current??

author: mikerj
author_rank: Super Contributor
timestamp: September 14, 2015, 09:28:37 am
content: Quote from: abhishekkumar1902 on September 14, 2015, 08:55:45 amOhm law gives you the answer. You control current by varying the applied voltage.

author: abhishekkumar1902
author_rank: Regular Contributor
timestamp: September 14, 2015, 10:21:55 am
content: Thanks for the reply mikerj. But if we are stepping down high voltage dc into low voltage dc(and as the power remain constant), will not the current be high at the output stage??

author: krish2487
author_rank: Frequent Contributor
timestamp: September 14, 2015, 11:51:01 am
content: You can either regulate voltage or current in such a scenario.Depending on the SoC, the regulated entity changes.During Bulk mode only regulate current (rather allow maximum safe current) and do not worry about the voltage.During floor mode, only regulate voltage and do not worry about current.They self regulate to a certain extent.Even for a 36Ah battery, if the PV is capable of supplying say 4A and you let the current go to maximum to 4A in BULK mode, the battery won't increase rapidly. You should remember you are pumping energy back into the battery, not just voltage or current. It will take a finite time for the battery to charge fully.Think of it like filling a tank. You can use a higher power motor to fill the tank, it will still take a finite time to fill up and not happen instantly. Using a lower power motor will just take longer to fill up the tank.

author: abhishekkumar1902
author_rank: Regular Contributor
timestamp: September 14, 2015, 03:20:05 pm
content: Thanks krish2487 for the explanation!
How to design a coupled inductor with auxiliary winding ?  - Page 1
Forum section: electronics / beginners

author: Patrick66
author_rank: Regular Contributor
timestamp: January 01, 2024, 03:22:19 pm
content: Hello everyone, can anyone teach me how to design a coupled inductor with auxiliary winding? Is the auxiliary winding considered multiple output loads since it uses two windings for the secondary side? If possible can someone share links that I can refer to. Thank you in advance guys for the help.

author: Konkedout
author_rank: Frequent Contributor
timestamp: January 02, 2024, 06:08:15 am
content: I think that your question is too broad and requires a textbook answer. The whole textbook.I think you might get more/better responses if you narrow it down to something specific you want to do. Give all the numbers and requirements you can think of.

author: RJSV
author_rank: Super Contributor
timestamp: January 02, 2024, 07:03:04 pm
content: Guessing a bit, but what comes to mind is that you could wrap a primary side using something like 40 turns, using a steel or ferrite rod.Then, a magnetically coupled secondary wrapped on top, after some insulating sheet goes around primary. I think you are asking about putting a third winding that would be simply wound, again, but not electrically connected, to either of the other windings...(?)

author: jonpaul
author_rank: Super Contributor
timestamp: January 02, 2024, 07:34:49 pm
content: Power supply? RF amplifier? RF Oscillator?Voltge? Waveform? Frequency? thruput power W VA?Jon

author: Jwillis
author_rank: Super Contributor
timestamp: January 02, 2024, 09:49:23 pm
content: Coupled inductor is to general of a term.Coupled inductors are essentially transformers. This can also included common mode chokes and topologies used for converters. Coupled Inductors for converters have a variety of Topologies such as SEPIC (Single Ended Primary Inductor Converter), Flyback, Flybuck, Buck-Boost (CUK), ZETA, and multiphase. Each of which would have their own winding configurations and applications . What type of Coupled Inductor and application are you interested in.

author: Patrick66
author_rank: Regular Contributor
timestamp: January 03, 2024, 03:00:41 pm
content: Hello everyone, I'm thinking of designing a flyback convert with auxiliary winding to supply the IC controller for constant output current regulation in LED driver. Here are my parameters, Vin = 220 - 260 Vac, Vout = 78V, Iout = 0.35 A, Maximum Pout = 27.3 W. Hope to hear from you guys.

author: johansen
author_rank: Super Contributor
timestamp: January 04, 2024, 06:21:01 am
content: Take the volts per turn on the transformer and multiply by the volts you need for the controller.Some fine tuning is needed especially for the 100 to 265v input supplies.You need enough volts for the low end but not so many you burn up the zener at high line voltage

author: Patrick66
author_rank: Regular Contributor
timestamp: January 07, 2024, 01:34:49 am
content: Can I use the equation from the attachment below to design my auxiliary winding ? Can I use the equations from the attachment below to design my transformer?
How to design a sidetone circuit for computer headset - Page 1
Forum section: electronics / beginners

author: hoverman
author_rank: Newbie
timestamp: November 08, 2015, 07:51:25 am
content: Hi All,I have spent a while on this but can't seem to find any resource that will show me how to design a sidetone circuit. What I'm aiming to do is make my own circuit that will allow me to hear my own voice when talking through my headset that is plugged into my laptop. It's got a 3.5mm TRRS connector with electret headset mic.The headset works fine when I plug it in, however I tend to talk too loud when using it because there is no sidetone. I'm hoping to build a circuit that is 5V powered so I can use USB as the supply. I looked at building a simple amp and connecting it in parallel in some way but I think that is way too "how ya going" and probably wouldn't work anyway. When I use my headset with my Xbox controller, I have sidetone (they call it mic monitoring) and I talk a lot softer as I can hear myself through the headset speakers. I have even looked into a software solution but there is a delay so useless!Any help would be much appreciated, thanks!Josh

author: homebrew
author_rank: Frequent Contributor
timestamp: November 08, 2015, 04:00:46 pm
content: Basically you would want to build three components:1) A microphone preamp with variable gain control (opamp + pot)2) A headphone amplifier (there are several integrated circuits available)3) A mixer (basically an opamp adder circuit)Then you would take the PC signal as an input to the mixer that would mix that signal with the output of the mic-preamp. The combined signal would then be feed into the headphone amp.

author: marinedalek
author_rank: Contributor
timestamp: November 08, 2015, 04:56:20 pm
content: Is it a windows laptop? Realtime low-latency monitoring should be built-in. Right-click on the speaker icon in the taskbar and go to Recording Devices. Select your headset mic from the list and go to Properties. Then on the Listen tab tick the "Listen to this device" option and make sure that your headset is selected as the device to listen on.

author: rx8pilot
author_rank: Super Contributor
timestamp: November 08, 2015, 05:41:44 pm
content: The delay is DREADFUL when it goes through the PC.Sent from mobile device.... Keeping it short and mis-spelled

author: jeroen79
author_rank: Frequent Contributor
timestamp: November 08, 2015, 05:50:37 pm
content: Would a passive attenuator/volume control be an option?

author: hoverman
author_rank: Newbie
timestamp: November 25, 2015, 07:21:50 am
content: Quote from: homebrew on November 08, 2015, 04:00:46 pmActually, that makes sense - thankyou.How would I connect the microphone to the input on the laptop? Just parallel it before the preamp that goes to the mixer? The laptop has it's own preamp, but I'm not sure how connecting the mic to both preamps would work.

author: tooki
author_rank: Super Contributor
timestamp: November 26, 2015, 01:21:48 am
content: You'd split the output of the external preamp, then route one of those outputs to the audio input of the PC, which you would change from microphone mode to line-in mode.
How to design a step up converter "practically" ? - Page 1
Forum section: electronics / beginners

author: Michael George
author_rank: Contributor
timestamp: April 09, 2017, 03:25:06 pm
content: There are many articles about how to design a boost converter the theoretically but I have some practical questions.Let's assume that the input is a 6V from a solar panel. And the output is 12V.I know that the frequency may range from 10 to 50 KHz.I select the frequency based on what?MOSFETs are used in most of the circuits that I see. Why a normal transistor can not be used (such as: 2N2222)?Should I feed the control circuit (oscillator) directly from the solar panel? or from the battery?I know they're basic questions but your answers are very important to me. I appreciate your help

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: April 09, 2017, 03:29:58 pm
content: engineers mostly copy data sheet application circuits after specing the project, selecting the controller chipcurrent, efficiency, size, cost are a few more factors to spec

author: keymaster
author_rank: Regular Contributor
timestamp: April 09, 2017, 04:21:44 pm
content: Quote from: Michael George on April 09, 2017, 03:25:06 pmyou can use an normal transistor but the mosfet will be more efficient . A transistor (when it is full ON) has a drop Voltage at the collector and emitter somewhere to 1.2v to 1.4v . But the mosfet (when it is full ON) will act as a resistor(Rds on) at the scale of mOhm.

author: orin
author_rank: Frequent Contributor
timestamp: April 09, 2017, 04:33:20 pm
content: You could always audit some of the courses here:https://www.coursera.org/learn/converter-circuitsPity they want money to do the exercises now.

author: Zero999
author_rank: Super Contributor
timestamp: April 09, 2017, 06:50:25 pm
content: Quote from: keymaster on April 09, 2017, 04:21:44 pmThat's a bit of a sweeping statement.At low voltages MOSFETs are generally more efficient than BJTs but at higher voltages (over 500V or so), especially at high currents, BJTs often have a lower voltage drop than MOSFETs, everything else being equal. Another option is the IGBT which combines both the low voltage drop of a BJT and high gate impedance of a MOSFET.

author: Seekonk
author_rank: Super Contributor
timestamp: April 09, 2017, 10:31:10 pm
content: I assume your desired question is about a low power boost converter for a 6V solar panel to 12V. I suggest for lowest possible overhead you get a cheap XL6009 boost module. Pin 2 should be floating, tie that to a voltage divider pot connected to the input panel voltage. With this you will be able to set the power point voltage and shut down the converter when it drops too low. This will prevent the converter from sucking the life out of the panel greatly reducing its possible output.
how to design a triangular wave generator for a frequency of 20Khz? - Page 1
Forum section: electronics / beginners

author: rakesh
author_rank: Unknown
timestamp: January 24, 2012, 01:31:42 pm
content: Hello everyone am trying to design a pulse width modulation circuit . To generate the PWM pulses i'll feed the triangular wave at one input and a control voltage at the other input of an comparator to get the pulses at the required duty cycle. I need to have a triangular wave which varies from 0 to 5Volt (not a 5volt peak to peak)at a frequency of about 20 Khz. i searched in the internet and found many of the circuits consists of a comparator and integrator to generate the triangular wave which varies peak to peak and those circuits uses a negative voltage supply. My guess is i don't need a negative supply for my kind of circuit design.I found the formula used to design the integrator which is based on the negative and positive saturation voltages of the op amps.Am really confused to design this circuit and also for choosing the right op amp with the enough slew rate for a proper triangular wave at the output.Am just a beginner with the electronics please correct me if i am wrong.
How to desolder these leads? - Page 1
Forum section: electronics / beginners

author: Osirus
author_rank: Newbie
timestamp: September 09, 2020, 10:51:36 pm
content: I have to replace a couple of bad transistors on this board. The Base pin came out just fine with a solder sucker, but the Emitter and Collector pins are in these eyelet things that appear to be on both sides of the board and I cannot get them out. I had to cut the leads to remove the transistors, but still can't get the leads out. I'm not even sure what they are or what their construction is like.

author: Jwillis
author_rank: Super Contributor
timestamp: September 09, 2020, 11:29:11 pm
content: They're rivets for extra structural integrity of heavier components. Not unusual on some single side through hole PCBs . How many watts is your soldering iron because 60W irons have some difficulty with these but not impossible.

author: Osirus
author_rank: Newbie
timestamp: September 09, 2020, 11:44:34 pm
content: I have a WES51 and had it at 700F. Should I be able to remove them by heating the pads underneath while pulling the leads from the top?

author: Jwillis
author_rank: Super Contributor
timestamp: September 10, 2020, 03:51:04 am
content: Just be careful not to over heat the traces. The epoxy doesn't like very hot temperatures for extended periods of time and the traces may lift from the board. I use a 250W Weller soldering gun for things like this if the 120W station won't do it. You can cut the wire flush and drill out the solder as well .

author: Osirus
author_rank: Newbie
timestamp: September 10, 2020, 06:14:03 pm
content: Cranked the heat all the way up and got them pulled out. Thanks!

author: ercapoccia
author_rank: Regular Contributor
timestamp: September 10, 2020, 07:01:59 pm
content: You would probably need hot air + soldering iron simultaneouslyOld technology iron are not good for big thermal mass.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: September 11, 2020, 03:49:32 am
content: One trick is to add solder.Not much, but just a little bit between your soldering iron and whatever you want to desolder.The goal is to improve the contact between the soldering iron and your object for better heat transfer.Using thicker tips int the iron also helps in this regard.
How to detect -5 volts? - Page 1
Forum section: electronics / beginners

author: rea5245
author_rank: Frequent Contributor
timestamp: January 18, 2019, 03:52:37 pm
content: Hi,I have a connector that can plug into two slightly different devices. I want to automatically detect which device it's plugged into. With one of the devices, there is -5V (yes, that's minus 5 volts) coming in on a pin. With the other device, that pin is not connected to anything. I can't connect the pin directly to a microcontroller, because -5V would damage it. What can I do to get a 0 or 1 signal to the MCU based on whether the -5V is there or not?Thank you,Bob

author: PartialDischarge
author_rank: Super Contributor
timestamp: January 18, 2019, 03:57:14 pm
content: 4.7V zener to the pin, then a pull up 100k resistor to the mcu. If not connected to anything the mcu will see 5V, if -5V is present at the pin, the mcu will see 0

author: rea5245
author_rank: Frequent Contributor
timestamp: January 18, 2019, 04:00:08 pm
content: Will the MCU's built-in weak pull-up suffice, or do I need the 100K resistor?

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 18, 2019, 04:08:53 pm
content: The weak internal pullup may work. Having said this, common resistors are ultra-cheap. And if you are using SMT devices, ultra-small too.My personal opinion is that for this instance I would use an external pullup. But other posters may think otherwise.

author: PartialDischarge
author_rank: Super Contributor
timestamp: January 18, 2019, 04:14:04 pm
content: The internal may be enough, but anyway I would also add a series resistor with the zener to limit the current in the mcu, just in case your -5V turn out to be -7 or -10V someday

author: coppercone2
author_rank: Super Contributor
timestamp: January 18, 2019, 04:23:46 pm
content: its good form anyway because its a external device and all external IO should be protected if possible by design, it will reduce the ESD some what.

author: macboy
author_rank: Super Contributor
timestamp: January 18, 2019, 05:14:46 pm
content: Connect 10k to micro's +5V rail, other end to a microcontroller input pin AND to the device pin via another 10k resistor. When device drives that to -5 V, then the voltage divider makes ~0 V, or logic low to the local micro. Otherwise it floats to +5 V, logic high. A zener (or better, a TVS) to protect the micro's input would be prudent, but its own input protection diodes plus the 10k resistor may be enough.

author: spec
author_rank: Frequent Contributor
timestamp: January 19, 2019, 05:47:41 am
content: Hi rea5245Another approach:
How to detect a sensor plugged in? - Page 1
Forum section: electronics / beginners

author: cdevidal
author_rank: Regular Contributor
timestamp: December 09, 2020, 09:24:58 pm
content: EDIT:Nevermind! The sensor output is high when not detecting any obstruction, which is perfect. If that ever goes low it will be recorded as an obstruction, and if it stays low the user will be notified.==I am thinking of including anE18-D80NK infrared proximity sensorin my chicken door product, but I want to have the Raspberry Pi detect if the customer has plugged one in, or if it breaks for some reason and is no longer passing current. So I need a voltage at a clear logic high (or low). I could use an opto-isolator to detect that there is a connection butthose have forward voltage of at least 0.8V. The power supply is 5V and the sensor requires 5V.What is another way I might detect the sensor is plugged in without using any voltage? Maybe a MOSFET? I triedthis Falstadbut setting the voltage of the bottom resistor high enough to turn on a FET gate may have an impact on the LED transmitter's current and voltage.If the sensor were normally-closed that would solve this problem. They only offer normally-opened so if it breaks or is disconnected, the RPi wouldn't know.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: December 12, 2020, 04:23:34 am
content: I use a sensor with two pairs NO/NC contacts.For signal processing, I use NO xor NC for periodic sensors (shaft rotation, for example). In this case, a malfunction of one pair will allow you to issue a warning, but still use this sensor. For static sensors, any signal. To detect an accident, I use NO=NC. In addition, the current consumption is monitored. This is some redundancy.Most often, it is enough to use a sensor that normally gives a signal of 1. If the wire is broken, the sensor is out of order, it will give 0, i.e. an alarm signal.NO sensor is very bad, it can not allow itself to be detected because in a normal situation it is silent. But you can equip this sensor with a local NO/NC relay, just next to the sensor in the junction box, then you can at least control the safety of the wire and switching.Or change the design, position of the sensor so that it is in the vehicle state under normal conditions.
How to detect open circuit conducting wire inside opaque sheath? - Page 1
Forum section: electronics / beginners

author: abdulbadii
author_rank: Frequent Contributor
timestamp: August 12, 2017, 02:41:01 pm
content: How to detect open circuit conductor inside opaque (untransparent) insulating sheath/cable in small scale. I meant the cable diameter only 1 - 2 mm with suspected spot within 10 - 15 cm length

author: hermit
author_rank: Frequent Contributor
timestamp: August 12, 2017, 02:49:09 pm
content: You do a continuity test with your meter. If you don't have one you can do a simple test making a circuit up with something like a light bulb and battery. If you are asking to specifically locate WHERE the break is, that requires more complicated/costly procedures.

author: tablatronix
author_rank: Regular Contributor
timestamp: August 12, 2017, 05:01:46 pm
content: Detect easy short 2 wires and continuity check.To find it you could use a tone generator trace set, or hack something up to do it, oscillator am radio etc.

author: Fraser
author_rank: Super Contributor
timestamp: August 12, 2017, 05:10:11 pm
content: If the wire is single core PVC insulated, just warm it up with a hair dryer and pull the cable. It will stretch where the break is locatedThat the simplest non technical test you can do.Fraser
How to determine discharge current of an unlabelled battery?  - Page 1
Forum section: electronics / beginners

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: March 19, 2023, 09:38:35 pm
content: I've got a LOT of lithium cells (18650, cylindrical, flat packs) without any datasheets available. How can I determine a safe and reasonable discharge current for them?My ideas:1. Discharging them at a constant current and measuring their temperature increase. If their temperature does not increase above 10C ambient at a constant current, that's stable.2. Measuring their internal resistance and basing it close to idea 1.3. Assuming all cells can do 3C constant discharge or 10C pulse (highly doubt this way is safe).

author: amyk
author_rank: Super Contributor
timestamp: March 19, 2023, 10:17:24 pm
content: 1C is definitely within limits, and you can measure their internal resistance using brief burst discharges. Here are some typical discharge curves to compare to:https://lygte-info.dk/review/batteries2012/Common18650IndividualTest%20UK.html

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: March 19, 2023, 10:49:20 pm
content: Quite a few of the cells are labelled "KY18350" (probably the dimensions, maybe the "KY" is the OEM?) pulled from disposable vapes. The others numbers on it are the date code and a QR code.

author: MrAl
author_rank: Super Contributor
timestamp: March 20, 2023, 01:08:47 pm
content: Quote from: LooseJunkHater on March 19, 2023, 10:49:20 pmHi,If they came from vapes they may be high current.This is a good question though even for cells that you assume are a given current based on advertising. If it says 10 amps continuous then it better be 10 amps continuous.I only use unknown types in low current applications though. For my high current apps i buy good cells from reputable sources. I also dont charge them too fast either because they last longer using lower charge currents. At one time 700ma was a good charge rate, but i often use just 500ma because i am almost never in a rush.Then there is the 85 percent rule. If you only charge to 85 percent of full capacity the cells last longer too.So slower charge, and 85 percent rule helps keep them useable for a longer period.
How to determine if an smd board has shorted component - Page 1
Forum section: electronics / beginners

author: jerryk
author_rank: Regular Contributor
timestamp: March 10, 2017, 09:05:04 pm
content: I am working on an smd board that had an alkaline batter spill on it. So far I have found two shorted components on the board and removed them. Additionally there were three IC's (logic gates, 555 timers) that were heavily corroded so these were removed and the pads cleaned with vinegar and then alcohol. While testing all the capacitors on the board I have found two that while in circuit showed continuity. I have removed them and they test fine with a capacitance of 100nf and no continuity. However, both mounting pads for each capacitor show continuity with ground and zero resistance across the pads. Does this indicate that there is a shorted component on the board that I have yet to find or is this really a legitimate circuit where both poles of a capacitor are attached to ground?Jerry

author: klr5205
author_rank: Regular Contributor
timestamp: March 10, 2017, 09:19:55 pm
content: Your instincts are correct that both leads of a capacitor would never go to the same net by design because in that case the capacitor isn't even in the circuit!Since the short is still present after removing what were likely decoupling caps, chances are that your power supply is shorted for some reason. Check the supply itself and any chips that it powers. One of them probably failed and shorted its power rails internally.

author: jerryk
author_rank: Regular Contributor
timestamp: March 10, 2017, 10:10:47 pm
content: The large electrolytic on the left was shorted so I have replaced it. There also was a shorted shottky diode at D5 on the left that had shorted and it's replacement has yet to be installed. The capacitor locations in question are C54 and C85 on the left and their traces on one side are difficult to follow since they connect to the center layer under the ground plane on the surface. I'm tempted to do the heat test by running some small voltage and current at both capacitors poles but I don't want to burn a trace that connects to an internal layer. I have checked all other caps and resistors/networks on the board and they seem to test ok. I'm open to suggestions.Thanks - Jerry

author: vk6zgo
author_rank: Super Contributor
timestamp: March 11, 2017, 12:28:33 am
content: Quote from: klr5205 on March 10, 2017, 09:19:55 pmNot always-------think parallel LC tuned circuit, where the inductor would often look like a short circuit to a dc test.Your DMM is a dc/low frequency device, & doesn't always recognise the circuit that is there.
How to determine spi pins? - Page 1
Forum section: electronics / beginners

author: sirtet
author_rank: Contributor
timestamp: January 28, 2018, 10:56:20 pm
content: So, I have this Bluetooth module with a piggyback pcb on it, and on that pcb is an soc (csr8645), that has an spi port, but I can't tell if the spi pins are on the pcb, cause it's a bga chip.There are 4 pins on the piggyback pcb (pins 12-15) that i guess are the spi ones, becausethey go to test points on the main pcb bottom side.But how to tell which is which?Is there a better approach to figure them out than trying lots of combinations,Sending a command and probing for an answer?

author: bitwelder
author_rank: Super Contributor
timestamp: January 30, 2018, 12:40:22 pm
content: step 1. Plug a logic analyzer (or an oscilloscope that can also decode SPI) and observe?step 2. Make guesses on the pins function and try to decode valid SPI messages?
How to determine which component is the right one - Page 1
Forum section: electronics / beginners

author: hawken
author_rank: Newbie
timestamp: July 12, 2011, 07:47:06 pm
content: I'm working on a small project, which involves fixing a power supply board from a monitor. I can see one component on the board that blew up which I'd like to replace--it's a six-pin transistor of sorts. It looks something like this:Printed on it is "F1 H01" and below that "CM0565R". I've done some searches for "CM0565R" thinking that it is the model number, and it looks like I'm at least partially correct. The problem is that there seem to be several variants of this component, and I have no idea which is the one I need.Can anyone give me some tips to help me choose the correct replacement?

author: Bored@Work
author_rank: Super Contributor
timestamp: July 12, 2011, 08:02:52 pm
content: The one that has the same package as your broken one, as per page 3 / figure 3 and pages 16, 17, and 18 in the datasheet. You did read the datasheet, didn't you?

author: hawken
author_rank: Newbie
timestamp: July 13, 2011, 11:43:18 am
content: Nope, I didn't read the datasheet. I'm a complete n00b about this. If I knew to do that, and knew how, I probably wouldn't be in here asking the question I asked.The datasheet lists several variants (e.g. 565RJ, 565RI, 565RG), and I don't know how to tell which is the one I've got.

author: GrumpyDave
author_rank: Contributor
timestamp: July 13, 2011, 12:25:35 pm
content: As BoredAtWork pointed out.On page three of the datasheet it shows three packages.G matches the part you have photographed (TO220).

author: Armin_Balija
author_rank: Regular Contributor
timestamp: July 13, 2011, 03:58:33 pm
content: Datasheets are your best friend. Read about the component you posted, compare to others that you've found, pick best replacement.

author: hawken
author_rank: Newbie
timestamp: July 14, 2011, 02:54:40 am
content: I'll do my best. As I mentioned in my post, mine isn't a G--it shows as H01. That's not listed in the data sheet.