hybridfree/eevblog-posts huggingface dataset:
need assistance with ID of SMD transistor - Page 1
Forum section: electronics / beginners

author: loguej
author_rank: Newbie
timestamp: May 03, 2021, 03:52:58 pm
content: Hello I am in process of trying to fix a digital VCR deck with a defective Video YbYcYr process board I have already traced down 2 defective "open" transistors Sot-23 typecode on top reads "45" to right of a rotated 90deg Low case m1 I have looked extensively on web for a cross reference but all the code books I have looked through indicate a 45 code reference is assigned to a 6 or 8 pin amplifier device this does not correspond to my package Type.Any assist would be most appreciated.Cheers

author: mvs
author_rank: Frequent Contributor
timestamp: May 03, 2021, 05:06:44 pm
content: 45 is BAS40-05 dual Schottky diodeshttps://www.vishay.com/docs/85701/bas40v.pdf
Need CD for JDS2900 60 MHz - Page 1
Forum section: electronics / beginners

author: BrianInTexas
author_rank: Contributor
timestamp: October 06, 2019, 06:22:23 pm
content: I bought a Juntek JDS2900 about a year ago.I just found a need to use it, and apparently I either did not get the CD or I lost it.I have searched the web with no result.The original seller is gone.Can anyone advise me where I might find the CD or its ISO file?

author: ledtester
author_rank: Super Contributor
timestamp: October 06, 2019, 06:28:40 pm
content: Try:https://www.mediafire.com/folder/av83u6hd7sivn/JDS2900_Signal_GeneratorFound it on this page:https://www.aliexpress.com/item/32867045945.html

author: BrianInTexas
author_rank: Contributor
timestamp: October 06, 2019, 06:38:51 pm
content: Got them.Thank you so much!

author: Deboscope
author_rank: Contributor
timestamp: November 19, 2019, 04:15:18 am
content: I have just ordered a JDS 2900 myself... (50 Hz)How is yours? Are you happy with it?
NEED Chip for halfbridge - variable frequency, variable duty cycle - Page 1
Forum section: electronics / beginners

author: MacIntoshCZ
author_rank: Regular Contributor
timestamp: August 08, 2020, 02:34:58 pm
content: Hello everyone,I have tesla coil with 17k turns with resonance frequncy about 3khz.I would like to know which chip i should use instead of ir2153 in schematic.IR2153 would be deadly. 50% on 3khz. I might see some fotons in visible spectrum =).http://danyk.cz/sstc4.pngauthor: danyk666 / diodegonewild* I will modify schematic for chip. No need to worry about pins connection etcThanks everyone for help.

author: MacIntoshCZ
author_rank: Regular Contributor
timestamp: August 09, 2020, 08:02:02 am
content: No one knows?I am searching but i just cant find any. I dont want variable duty cycle through feedback on load.Hm maybe tl494 could do that job

author: elmascapoeira
author_rank: Newbie
timestamp: February 20, 2022, 06:28:34 pm
content: i know its a bit late but anyway, of you connect to ground the pin3 of the ir2153 it power off the output, so you can try connect pin3 with a ne555 and thus reducing the duty cicle with it, but how the hell you have a coil with 17thousands of turns? it will dont work, you need about 800-1600 turns
Need circuit diagram for Hopkinson test of dc series motor - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: January 11, 2020, 03:46:41 pm
content: Hello guys i need circuit a circuit diagram for Hopkinson test of series wound DC motor.N.B There are lots of circuit for DC Shunt motor.Please do not post the circuit for dc shunt motor in the comment section.

author: andy3055
author_rank: Super Contributor
timestamp: January 12, 2020, 05:07:33 am
content: This one?https://circuitglobe.com/hopkinsons-test.html

author: MagicSmoker
author_rank: Super Contributor
timestamp: January 12, 2020, 12:51:10 pm
content: Quote from: khatus on January 11, 2020, 03:46:41 pmThe series DC motor is rarely (read: practically never) used as a generator because it is not reliably self-starting and the output voltage increases with loading, making it very difficult to control unless the load draws a constant current. IIRC, series field generators were used to supply arc lamps at one point (early 1900's) but that's about it.This is also why you don't see regenerative braking implemented with series field motors, btw.
NEED CLARIFICATION  - Page 1
Forum section: electronics / beginners

author: techguru
author_rank: Regular Contributor
timestamp: December 21, 2017, 05:47:08 pm
content: An additional LM395(Q2) is driven from the negative power supply lead of the LM308 to provide some output current sink capability(2A) so the supply can be quickly programmed even with large capacitive loads? wHY DO WE WANT Q2 AND WHY CURRENT SINK IS NEEDE IN POWER SUPPLY?

author: hugo
author_rank: Regular Contributor
timestamp: December 21, 2017, 06:50:36 pm
content: Hi Guru,Let's say we have a lab power supply without a load. You turn the voltage adjust pot clockwise/anticlowise the output voltage increases/decreases accordingly.With large capacitive loads the output voltage will not follow exactly the voltage adjust pot movement, so to fix the issue that current sink stage is needed.

author: techguru
author_rank: Regular Contributor
timestamp: December 22, 2017, 07:03:11 am
content: Hi hugo,can you explain with a situation ? it will be helpfull.

author: nicalitz
author_rank: Regular Contributor
timestamp: December 22, 2017, 01:48:40 pm
content: The larger the capacitance of your load, the slower the rate of discharge (generally speaking). If you want the output voltage of your power supply to respond to adjustments in a timely manner, you need to enable said capacitive load to discharge and quickly and efficiently as possible. This is why you need Q2

author: techguru
author_rank: Regular Contributor
timestamp: December 23, 2017, 03:12:44 pm
content: hi nicalitz,Then you mean to say that Q2 transistor act as a resistor and Load capacitor tends to discharge through this resistor. Is it correct???

author: Damianos
author_rank: Frequent Contributor
timestamp: December 23, 2017, 05:13:24 pm
content: A transistor, usually, acts as a ... transistor! It is a device that the conductivity, between collector and emitter, depend on the bias of the base.The circuit is designed like an asymmetrical class B amplifier. When the output has to be reduced (for whatever reason) the op-amp tries to do this by pulling current through R11 and R14 to the R13 that biases the Q2 and it "helps the situation"...

author: Raj
author_rank: Frequent Contributor
timestamp: December 26, 2017, 12:47:47 pm
content: guru baba shishayaexplaination with water anology.Think of the capacitor as a water tank and power supply is feeding water into that tankthe voltage is water level...you have currently set the pump (power supply) to mantain water (voltage) to 20cm (20 volts) high...later you push a button to bring it down to 10cm (10 volts)without opening a in the tank drain (artificial load q 2) the water will remain 20cm high (20 volts potent) until the water evaporates (the ineffitiencies of capacitor emptys it)
Need data from a graph?! - Page 1
Forum section: electronics / beginners

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 14, 2016, 08:48:51 pm
content: A reminder this exists:http://imgur.com/gallery/XaB7chttp://arohatgi.info/WebPlotDigitizer/app/Tim

author: bitseeker
author_rank: Super Contributor
timestamp: August 14, 2016, 10:15:54 pm
content: That's neat. Thanks, Tim.

author: gardner
author_rank: Regular Contributor
timestamp: August 15, 2016, 12:53:06 am
content: I have used Engauge before for this.https://sourceforge.net/projects/digitizer/It hasn't been maintained in ages, but it still works for the things I've needed.
Need diode ID help - Page 1
Forum section: electronics / beginners

author: jeffjmr
author_rank: Regular Contributor
timestamp: April 11, 2022, 01:24:57 pm
content: In the process of bringing an HP 428B back to life.Among other things, I suspect some diodes may be part of the problem.Here is how they are described by the parts list:si 30 wiv 50 mA 2 pF 2nsA part number, PG512 is listed for this one, but a web search comes up empty. And a capacitance spec on a diode is something I haven’t seen before, and 2ns Trr seems unobtainium. The fastest I can find on Mouser and Newark is 4ns.germanium 60 wiv 1 microsecond TrrThis one has no part number, and is that Trr spec for real?Pics attached. They don’t look like anything special, nor do I see any signs of them having been replaced. There are some numbers on them but I’ll have to pull them to read them.Any ideas on what I could use for replacements for these would be greatly appreciated.Thanks,Jeff

author: bdunham7
author_rank: Super Contributor
timestamp: April 11, 2022, 02:00:32 pm
content: The first one is a 1N3956, the second a 1N54AS. Both are available from American Microsemiconductor--for $95 and $492 each.The 1N3956 probably needs to be replaced with the same thing. The NTE 177 is purportedly a substitute, but I wouldn't trust that. There's a local mil-spec surplus supplier near me and I may be able to obtain 1N3956 from them, but I'd have to go there when I'm in their area for something else. They show them as available, but until they are in hand you just don't know.The 1N54AS might just be what they used for a germanium diode and perhaps a 1N34A will work. How is it used in the circuit? I can't find datasheets at all for the 1N54AS, but I can for the 1N54A. However, they are so brief that comparisons are difficult.Edit: 1N54A has much lower reverse leakage current, I'd assume the 1N54AS is a 'select' version with even lower IR. So you may have to do some scrounging and/or selectinghttp://pdf.datasheetcatalog.com/datasheets/newjerseysemiconductor/1N54A.pdf

author: jeffjmr
author_rank: Regular Contributor
timestamp: April 11, 2022, 02:19:34 pm
content: $2158 worth of diodes, eh? Well, if those are indeed faulty, then my 428B will be an attractive paperweight.Even one of the $95 units exceeds the cost of the meter.Thanks for the quick response.

author: bdunham7
author_rank: Super Contributor
timestamp: April 11, 2022, 09:00:01 pm
content: That's just the hoarder/reseller silliness. They hope someone will approve a purchase out of desperation. I'm sure you can round up something for a few bucks. You might just get 10 or so 1N54A or NTE109 from eBay or Digikey marketplace and select the ones with the lowest leakage. Or, I wonder if a 1N916 would work. Hmmm.Let me know if you want to to scrounge the 1N3956.
Need direction about logic analyzer with state analysis.hantek LA5034? any good? - Page 1
Forum section: electronics / beginners

author: Riaj159
author_rank: Newbie
timestamp: June 19, 2017, 06:03:04 am
content: hello everyone !i'm stuck with choosing a logic analyzer with state analysis capabilities,where i can feed external clock via dedicated channel,but not able to find much under 100$ range other then Hantek LA5034 with 34 channel ,500mhz sampling,150mhz bandwidth .The price is almost near 80$.I know that the software of that logic analyzer sucks, for protocol analysis i have already purchased CY7C68013A based logic analyzer that can be used with sigrok pulse view.So protocol analysis is not something i really care about,is it gonna worth?? also is there any chance that Hantek LA5034 will get Sigrok pulse view support??? thanks in advance

author: millo110986
author_rank: Contributor
timestamp: November 27, 2017, 09:38:14 am
content: Hi, i have this LA, can you help me to configure it for read a microsd data?
need explanation of this little code step by step - Page 1
Forum section: electronics / beginners

author: ect_09
author_rank: Contributor
timestamp: November 14, 2014, 10:22:50 am
content: Code:do{ if (Button(&Switch_Port, Switch_Pin, Debounce_Time, 0)) {if (!Switch) { LED = ~LED; }while (!Switch); // Wait for release of the button } }while(1); // Infinite Loop }code is taken from this linkhttp://embedded-lab.com/blog/?p=164

author: Jeroen3
author_rank: Super Contributor
timestamp: November 14, 2014, 10:33:29 am
content: do{if (Button(&Switch_Port, Switch_Pin, Debounce_Time, 0)) {if (!Switch) {LED = ~LED;}while (!Switch); // Wait for release of the button}}while(1); // Infinite Loop}Does not compile.But it should toggle the led is the result of Button() is true and Switch is false. It will continue to the infinite loop when Switch is/becomes true.

author: briselec
author_rank: Regular Contributor
timestamp: November 14, 2014, 11:33:56 am
content: Code:do{if (Button(&Switch_Port, Switch_Pin, Debounce_Time, 0)) { // calls a library function that debounces the button pressif (!Switch) { // if Switch is equal to 0.LED = ~LED; // bitwise negation. If the Switch is equal to 0 and the LED is off it becomes on, on becomes off.}while (!Switch); //an empty while loop. execution is stuck here till Switch is not equal to 0.}} while(1); // Infinite Loop } // 1 is always 1 so we're stuck in a continuous do..while loop.
Need for buffer on this circuit?  - Page 1
Forum section: electronics / beginners

author: jeremy0203
author_rank: Contributor
timestamp: September 25, 2018, 04:01:45 pm
content: So in learning electronics I am finding it helpful to take circuits and break them down to see what components are used and what their fucntions are for the application.My question is on these two circuits shown in the picture. The function of both is exactly the same. They both take 4 pairs of differential signals into an am26c32 which are output to 4 different outputs. These outputs are pwm sort of style signals for rgb led lights such as ws2811 protocol. I'm wondering with the white board the signals are fed through a quad buffer after the diff receiver. Do you feel this would provide any benefit as to without it? Also there is resistor in series on the output of the signal from the buffer, from what I can find through Google searches this seems to be to reduce ringing and/or reflections on the line?https://ibb.co/gh3VXUhttps://ibb.co/k4Utmp

author: bson
author_rank: Unknown
timestamp: September 27, 2018, 12:46:34 am
content: I can't see the buffer making any difference. The AM26C32 looks like a pretty tough little cookie.
Need full firmware (full dump flash) oscilloscope Singlent 1102cml - Page 1
Forum section: electronics / beginners

author: igor_bin
author_rank: Newbie
timestamp: June 17, 2014, 09:34:41 am
content: Help me!Need full firmware (full dump flash) oscilloscope Singlent 1102cml or any other series Siglent 1000cnl or 1000cml (Atten 1000cnl or 1000cml)Please send me sv7@ukr.netThank you!
Need guidance on converting set of resistance values to distinct output pins - Page 1
Forum section: electronics / beginners

author: nall
author_rank: Unknown
timestamp: January 01, 2022, 11:56:22 pm
content: I have an existing device that has 3 buttons. It has a 3 pin interface where Pins 1 and 2 will either be open (nothing pressed), short (button 1 pressed), a 4.7k resistance (button 2 pressed), or a 10k resistance (button 3 pressed). Pin 3 is ground.I'd like to adapt this to a different interface where each button has its own pin that it connected to ground if the button is pressed.I'm trying to figure out the general approach to take. I tried creating a circuit with 3 PNP transistors where a single transistor would turn on (and connect its collector to ground) for a given button press, but I have been unsuccessful (multiple transistors turn on for a given button press).I'm not looking for the circuit itself, but just a nudge in the correct direction.Thanks!nall.

author: rstofer
author_rank: Super Contributor
timestamp: January 02, 2022, 01:09:30 am
content: One way is to use diode logic. Assume the output wires (O1 and O2) have pull-up resistors somewhere. Then for button 1, orient a single diode to pull O1 to ground (anode to O1, cathode to button 1), button 2 pulls both O1 and O2 to ground and button 3 pulls only O2 to ground. Four diodes total. Other encoding schemes will work as well.Now, the outputs won't get all the way to ground, they'll be about 0.7V above ground or at the pull-up voltage. It should still work in most uC applications but I don't know exactly what the outputs connect to.Of course, this is negative true logic, the outputs are pulled to ground by the switches and normally float high. That may be backwards and require a couple of transistors to invert the logic.

author: ledtester
author_rank: Super Contributor
timestamp: January 02, 2022, 02:59:34 am
content: Here's a circuit idea you might be able to use...If Q2 is in saturation then signal A won't be able to turn on Q1 effectively computing "A and not B".
Need Help!! DIY electronic load problem. - Page 1
Forum section: electronics / beginners

author: Ravishka77
author_rank: Newbie
timestamp: September 18, 2022, 06:01:46 am
content: I tried to built this electronic load but NANO constantly outputs PWM signal at 70% even when load just turned on for setupI don't know the reason If you got any insight into this plz help.I'm just a automotive tech so I'm not used to diagnosing these Thank you for reading this cry out for help.

author: Ravishka77
author_rank: Newbie
timestamp: September 18, 2022, 06:03:18 am
content: https://www.instructables.com/DIY-Adjustable-Constant-Load-Current-Power/Code is available hereIf theirs a better alternative plz let me knowThank you.

author: m k
author_rank: Super Contributor
timestamp: September 28, 2022, 03:57:09 pm
content: Last comment of a link is indicating that circuit and/or software can have some issues.

author: MrAl
author_rank: Super Contributor
timestamp: September 28, 2022, 11:09:39 pm
content: Quote from: Ravishka77 on September 18, 2022, 06:01:46 amHi,If you have a scope you can take some snap shots of the waveforms in different places and post here. That will help tell what is not working right.
Need Help!! How to interface Analog output from the current sensor using D SUB 9 - Page 1
Forum section: electronics / beginners

author: Sairam
author_rank: Newbie
timestamp: February 23, 2018, 08:25:35 am
content: Dear Members,I am doing project goal is to get the analog output voltage from the optical current sensor as a input data to the raspberry pi 3.Please find the sensor external overview circuit where you can find the IMX2 D SUB 9 female pin (analog output).Can I use USB to RS 232/RS 422/ RS 485 Adapters which are available in the market as transmission channel from sensor IMX2 D SUB 9 to raspberry pi 3 via USB outlet.?If yes, What kind of drivers needed and do we have any example program code for this kind of system.Thank youSairam

author: danadak
author_rank: Super Contributor
timestamp: February 23, 2018, 10:46:44 am
content: The text you extracted about the analog outputs connector seems toindicate that the connector carries analog signals, not digital whichUSB is.Do you have a link to the manual/datasheet for the module ?Regards, Dana.

author: Sairam
author_rank: Newbie
timestamp: February 23, 2018, 12:06:00 pm
content: Please find the FOCS sensor details.https://library.e.abb.com/public/74d5555d2a9c2998c12579a00038ff0a/FOCS_brochure_3BHS362996_E01.pdfThank youSairam

author: danadak
author_rank: Super Contributor
timestamp: February 23, 2018, 12:16:52 pm
content: That's just a brochure, really need a manual to confirm that the DB9 is carryinganalog signals, not digital signals.Regards, Dana.

author: Sairam
author_rank: Newbie
timestamp: February 23, 2018, 12:19:15 pm
content: I am not sure whether to share actual module manual file. That's why I am sending the only IMX2 Pins allocation.Yes,Dana you are right those are analog signal only.
Need Help !  Multimeter Mastech MS8260F  or   UNI-T UT61C - Page 1
Forum section: electronics / beginners

author: Martinus
author_rank: Newbie
timestamp: November 11, 2011, 10:02:38 pm
content: Hello,I am looking for a digital multimeter but I haven't a high budget !I have found on the internet a lot of brand, and I hesitate between a Mastech MS8260F and an UNI-T UT61C with RS232...Both are catIII and IV.links :http://www.mastechmeters.com/product/meters/digital-multimeter/digital-multimeter-ms8260f.htmlhttp://www.uni-trend.com/UT61C.htmlI use very often multimeter so I need a well-built and accurate unit.Please help me, I don't know theses chinese brand !Do you think that a USB port or RS232 is really usefull ? Maybe for record evolution of temperature ??Thank you very much,Have a good weekend.Martin

author: Unknown
author_rank: Unknown
timestamp: November 11, 2011, 10:34:18 pm
content: I wouldn't trust any multimeter in that price class with Cat III/IV measurements. Most meters in Dave's $100 shootout didn't even appear to have enough protection for these circuits. USB/RS-232 is occasionally useful, but I would focus on the core features first. Between those two, I would probably go with the Uni-T because I've at least seen some experiences (search the forum) which seemed fairly positive, no detailed review or tear down, though. Negative was the slow continuity. No idea about the Mastech. Watching Dave's review in the $100 DMM shootout about the UT-71 might give you an idea what to expect, although this is a more expensive model.

author: Lightages
author_rank: Unknown
timestamp: November 12, 2011, 01:59:35 am
content: I have not had one in my hand, but I have read good things about the Amprobe 240. There is a teardown/minireview of it here on this forum. Based on what I know of the UT71 series ( I have UT71E) and what I see about about the Amprobe 240, I would buy the Amprobe 240. It seems to have all the safety and features that anyone could use in a handheld, especially for the price. As far as its ultimate accuracy and stability, I have no idea.

author: Martinus
author_rank: Newbie
timestamp: November 12, 2011, 10:05:33 am
content: Thank you for your answer ! The UT71 is too expensive for me actually, but if it's a good quality, we can think that the UT61 isn't too bad...The Amprobe 240 has similar caracteristics, it's an american brand. I can't find it for less than 60€ wih shipping cost...I know I am fussy, but I havn't more than 50USD (around 40€) to spend for a DMM.

author: Nermash
author_rank: Frequent Contributor
timestamp: November 12, 2011, 12:09:05 pm
content: Between these two I would go with UNI-T. I have a UT60B branded Voltcraft VC820 and it is still working fine.

author: Martinus
author_rank: Newbie
timestamp: November 12, 2011, 03:09:56 pm
content: Ok, thanks for your advice ! I think I will buy the uni-t..I am waiting this evening for more opinion and place my order.Have a good day.Martin
NEED HELP - 12v LED strip with ESP32 and 12v 33.3Amps big power supply - Page 1
Forum section: electronics / beginners

author: dst161
author_rank: Newbie
timestamp: December 26, 2022, 03:32:03 pm
content: Items used:1. 240v AC to 12v 33.3Amps DC big power supply2. 2811 LED Strip: 12v 5mts with 300 LEDs (60 led / 1.mtr)3. ESP32 - WROOM development board4. 12v to 5v LM2596-NR BUCK converter step down moduleI have done everything as mentioned in the following video for my setup:https://youtu.be/zbhdH-qSANcThe only difference in my setup and the video is that in the video a 12v to 5v step down converter is used where as I have used a LM2596-NR BUCK converter to reduce the 12v coming from the big power supply down to 5v and then connected the +ve to VIN connector on ESP32 and -ve to GND connector.I have connected the green (data) wire from the LED strip to D4 connector of the ESP32 board.I have used the 0.13.3 WLED installed and installed it on ESP32 board fromhttps://install.wled.me/using the instructions.After all this setup is done, I um able to connect to the ESP32 board over wi-fi using the app and changed the GPIO to 4 in the app.(Screenshot of the app attached)PLEASE HELP... DONT KNOW WHAT ELSE TO DO NOW.

author: ozcar
author_rank: Frequent Contributor
timestamp: December 26, 2022, 09:04:38 pm
content: Maybe a level shifter is required between D4 and the strip, which you did not mention (sorry, I'm not going to watch a video to find out what you might or might not have done).
Need help - Page 1
Forum section: electronics / beginners

author: Cujo
author_rank: Regular Contributor
timestamp: November 30, 2020, 07:59:42 am
content: There are 3 unknowns in this problem, and I suck at simulations equations. So is it possible to turn this into a matrix problem?

author: pwlps
author_rank: Frequent Contributor
timestamp: November 30, 2020, 08:18:59 am
content: 1/16k= 1/R1+1/R2+1/R3=1/R1+1/2R1+1/3(2R1)= 1/R1 *(1+1/2+1/6)

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: November 30, 2020, 02:45:46 pm
content: What matrix? Fairly simple algebraThere really is only one unknown, which is R1/16 K = 1/R1+1/R2+1/R3 R2=2*R1 R3= 6*R11/16K= 1/R1+1/2R1+1/6R11/16K= (6+3+1)/6R11/16K=10/6R16R1=160K R1=26.6666666666KIn resistor parallel, The total resistance will always be smaller than the smallest resistor value
need help and ideas for calibrating a UNI-T UT(D)2042C scope (11 years old) - Page 1
Forum section: electronics / beginners

author: Pfriemler
author_rank: Regular Contributor
timestamp: April 19, 2021, 07:40:55 am
content: Hi folks,this is my fist post, so it has to be to the beginners, hasn't it?Should it better be placed in "Metrology"?I am looking for a way to improve the disastrous basic accuracy of my UNI-T UTD2042C scope.After fresh internal calibration (Utility -> Self Adj.) both probes show in both inputs and in 1:1 as well as 1:10 at 10 V DC only "9.20V", which is an error of -8%. This is not dramatic for an ugly thing like that but increasingly annoying and I'm tired of the conversion now.Reichelt sold this device 10 years ago (it is named UTD2042C, but I wonder if there are any mean differences to UT2042C).I sent it back for replacement and got an equally inaccurate one in return (it was a different, thanks to docu-photos). At that time I shrugged it off as a serial error.Of course, I did not found any adjustable screws inside.What bothers me: The 1kHz 3V test signal (for probe calibration) is shown as a 2.96 or 3.04 amplitude, which fits well. An old Voltcraft DMM750 scopemeter indicates 3.25V and half a dozen of DMMs get it as an 1.58 V average. So if the test signal and the internal calibration are derived from the same source, this can be the point where I have to start, because if it calibrates to a higher voltage it will measure lower values.I simply tried to pull down the test signal with an external 10k (lowers signal by -5%) during calibration, but without success.I have simply no idea how calibration works and if there are any procedures to do like for some DMM (key combinations and calibrating with external references and so on).These are my questions:1. to all UT-2xxxC owners: Are yours also so inaccurate or ok?2. has anyone ever found any successful help regarding this?Any hint is welcome. Service manuals or a circuit would be the best, but I found no single hint that something in this way exists at all. Only a German Site did offer a calibration for this thing some years ago, so in principle there must be a way.Before I get a lot of well-meaning advice:a) of course I know about the 8-bit-limits and that the displayed jumps are 20 mV when the voltage changes. But already 9.8 or 10.2 V would be a significant improvement.b) yes, I know that the whole thing is not very good. It will be replaced soon. But this is a different matter and should not discussed here.btw: Thx to DeepL :-)
Need help with antenna selection  - Page 1
Forum section: electronics / beginners

author: logictom
author_rank: Unknown
timestamp: February 26, 2012, 05:50:45 pm
content: I am planning on picking up a Telit GM862-GPS module and I'm trying to find a suitable GPS & GSM antenna to go with it.From the datasheet I require a 50ohm GMS antenna with a gain < 3dBi and 50ohm GPS antenna with 1.5dBi < gain < 4.5dBi and amp typical 23dB (max 27dB). See pics for full spec.I've found an antenna (Farnell 1735194) but it is 6dBic (LNA 27dB). Is there a difference between dBi and dBic and what practical difference would it make using this as it's 1.5dBi more than specified?If anyone knows a good source of integrated GSM & GPS antennas with a magnetic base I would appreciate any links.Module:http://uk.farnell.com/telit-wireless-solutions/gm862gps730/module-gsm-gprs-quad-band/dp/1710713Antenna:http://uk.farnell.com/multicomp/oe-cmb-rd-c5c6/antenna-gps-gsm-combo-sma-fme/dp/1735194

author: logictom
author_rank: Unknown
timestamp: February 26, 2012, 06:01:54 pm
content: I'd like to avoid ebay item but would this one be suitable?http://www.ebay.co.uk/itm/Magnetic-Quad-band-GSM-GPS-2-1-antenna-2dBi-3dBic-/130600017982?pt=PDA_Accessories&hash=item1e685e203e#ht_1558wt_1037This would be ok for for testing but I would ultimately want one I could get from one of the usual suppliers.
Need help authenticating a Hakko soldering station - Page 1
Forum section: electronics / beginners

author: PeterMadach
author_rank: Contributor
timestamp: March 02, 2017, 08:16:41 pm
content: Cheers guys!I've just found a legendary Hakko 936 on a local auction site, and it has a really nice price tag, but I'm wondering if its authentic or not. I've googled the 936 and the pics showed a black device box and the iron had a black handle as well, but the one I've found is more like a classic bone-white. Could this be a real thing? Unfortunately the pics are really crappy quality, and doesn't show much.https://www.jofogas.hu/bekes/Hakko_forraszto_allomas__paka__tarto_62359316.htm?first=1

author: GreyWoolfe
author_rank: Unknown
timestamp: March 02, 2017, 10:42:45 pm
content: It isn't easy to tell by looking at some pictures. If the pics are close up and hi res, you can see that the letters/logo aren't quite as clear and sharp on some of the fakes. Others are done very well. Under the hood is where you can see the difference. I had one but I bought mine brand new from an authorized US seller. I will say that the case/wand on mine was black not white. I don't know if there was color options or not. The 936 is one of the most copied/cloned/faked Soldering Stations around.

author: helius
author_rank: Super Contributor
timestamp: March 02, 2017, 11:50:38 pm
content: The original 936 and its 900S and 900L handles were originally "bone-white" as you say, later the "ESD" versions were black. I'm not entirely sure what was different about the ESD models, but IPC standards require <2ohms from the iron tip to ground. Most of the fakes seem to be based on the black model.
Need help changing electric gate remote - thank you  - Page 1
Forum section: electronics / beginners

author: eevblogfan
author_rank: Frequent Contributor
timestamp: June 12, 2013, 05:32:38 pm
content: heyI got two remotes , one is genuine and one I might be able to tweak to fit the taskthe following pic is showing the output waveforms :

author: eevblogfan
author_rank: Frequent Contributor
timestamp: June 12, 2013, 05:56:19 pm
content: the green wave is the okay remote . the one we need to copythe yellow is the one we need to tweakthe boards :the first board is the okay onethe others are :1) botton side2) upper side

author: Paul Price
author_rank: Super Contributor
timestamp: June 13, 2013, 03:36:24 am
content: You can record the correct waveform for the control codes and then use a PICC or other MCU to generate these codes on button press and feed this to the modulate in lieu of the existing chip. I have done this with TV remotes to make remote controls to control other equipment and motors.

author: SeanB
author_rank: Super Contributor
timestamp: June 13, 2013, 04:58:43 am
content: First is a generic dip switch remote, while the others look like a rolling code remote. The top one is a $10 unit here, which is a learning remote that will record and play back the code from almost any non rolling code remote with no problem. The DIP switch ones are somewhat manufacturer dependant as they use slightly different timings on the same basic holtek code engine, which is a common item. Those cost from $5 depending on the type.

author: eevblogfan
author_rank: Frequent Contributor
timestamp: June 13, 2013, 09:47:31 am
content: they charge for 41$ for new remote , so I gave it a tryQuoteI don't know anything related to digital yet , is there any way you may help me with that ?

author: amyk
author_rank: Super Contributor
timestamp: June 13, 2013, 10:57:36 am
content: First one is a Holtek but I can't read the part number on it. Looks like a 12-bit code though.The one you want to change is aPT2262which is a 12-tritencoder. You can see the 10x2 solder pads + 2 buttons on the back.If they work on the same frequency you could try setting the address using either 0 -> 0, 1 -> 2 or 0 -> 0, 1 -> 1 and compare the waveforms...

author: SeanB
author_rank: Super Contributor
timestamp: June 13, 2013, 04:31:55 pm
content: Depending on where you are I could probably post you some cheaper than the $41..........

author: eevblogfan
author_rank: Frequent Contributor
timestamp: June 13, 2013, 06:53:48 pm
content: heyI am located in israelthese are not mine . they are Job ( although they are my father's friend )
Need help choosing and finding a power transformer. - Page 1
Forum section: electronics / beginners

author: SittingBear
author_rank: Contributor
timestamp: August 11, 2014, 03:17:53 pm
content: Hello EEVBlog Forums,I'm planning on making my own power supply for my project which requires anywhere from 24Vrms to 28Vrms in. The transformer will feed to a rectifier, a filter, and a smoothing capacitor.The circuit itself will be 3 boost drivers. Each boost driver will drive a, roughly, 48V LED strip (16 LEDs in series; average Vf is 3.0V). To get best efficiency out of the driver, I want to be as close as possible to the output voltage without exceeding the maximum Vin of the drivers. I could use two separate power supplies, though I would rather use one transformer.The maximum current draw from each driver is 1.0A, so I'm guessing my maximum current handling capability should be > 3.0A.Since I do not know a lot about power transformers I am asking for advice in helping me find and choose a transformer with the current handling capability without accidentally choosing the wrong transformer, or paying a hefty amount for something that is overkill.If there's any information I have left out, I'd be happy to answer it.Thanks,-Bear

author: German_EE
author_rank: Super Contributor
timestamp: August 11, 2014, 03:49:22 pm
content: No transformer is needed in this application. Feed your 24VAC into a voltage doubler and get 48V DC out. In view of the currents involved you might need large electrolytic capacitors but that's the only problem I see.

author: SittingBear
author_rank: Contributor
timestamp: August 12, 2014, 02:25:46 am
content: Quote from: German_EE on August 11, 2014, 03:49:22 pmI'm not sure a voltage doubler would be able to handle the load.
Need help designing power supply - Page 1
Forum section: electronics / beginners

author: ja421
author_rank: Contributor
timestamp: May 08, 2015, 06:10:45 am
content: I have a vehicle with twin LED headlights. The LED's have a cooling fan that runs when the LED's are on.The bike operates at 13.8v -- due to other projects on the bike, I have a stable 12v, 5v, and 3.3v available (all limited to 3amp tho).The lights have a low & high mode. When switched to high, the fan spins faster. The difference between high and low is voltage (about 10 on low and 20 on high). Fast switching between high and low results in the led slowly heating up, as the fan doesn't instantly spin faster.The goal is to build a headlight modulator to cycle (ala sine wave) between 10v and 20v about 2 to 3 times a second while leaving the fan on high to keep it cool enough.I've done various projects on my own, but I have no idea how to start designing the power supply that i can manipulate via an arduino PWM pin (5v). I don't want to randomly pick some opamp & hope it works with trial and error until it does.Would someone be able to help me?

author: picandmix
author_rank: Frequent Contributor
timestamp: May 08, 2015, 09:56:26 am
content: You could sort the problem out using the method you suggest, but it seems a little complex.My own take would be to add a little delay timer so when the circuit goes from hi to lo he fan in kept running at high speed for a minute or two longer, so ensuring the led is fully cooled ..?Or cannot the fan simply be wired for full speed all the time ..|?A circuit diagram of the fan, led and their controllers wiring would help for a more detailed reply.

author: ja421
author_rank: Contributor
timestamp: May 09, 2015, 09:24:41 pm
content: There's not much to see regarding the circuit -- 12v+/gnd goes into a power supply that bumps it up to 20v.4 leads come out (two pair, both V/gnd) One pair goes to the fan, one goes to the led. Circuitry in fan & led is not documented.I want to power the fan 100% on "high"; but ramp up/down the led. Regulations say motorcycle can 'modulate' the high beams during the day -- BUT they must not "flick on and off" they *must* ramp up/down.. it's a fine line I guess... I can buy a pre-made one, but it will ramp up/down 12v not 20v...I had a guy who thought he could build it, but he flaked on me. I can read a schematic & solder it up -- but I don't know how to build the opamp circuit needed... or even how to begin -- I was not a science major....Thanks for your time.
Need help downloading a file from Baidu - Page 1
Forum section: electronics / beginners

author: DavidAlfa
author_rank: Super Contributor
timestamp: June 25, 2022, 06:10:52 pm
content: Does anyone have access to baidu?All chinese websites use QQ, WeChat, and they all require chinese phone and ID.I want to download this file:99_BT201方案_KT1025A_B_资料_V2.4_20200421.zipbut no way!

author: bg8aak
author_rank: Contributor
timestamp: July 19, 2022, 06:17:33 am
content: It's about 25MBI cant upload heregive me a email
Need help explaining an audio line-in circuit  - Page 1
Forum section: electronics / beginners

author: tomo
author_rank: Newbie
timestamp: October 07, 2015, 12:58:53 pm
content: Hi,I am trying to add an additional audio input to my old Sony HCD-CPX1 stereo by re-purpose the tape deck. After looking at the service manual/schematics and the data sheet for the input selector chip I figured out that I would only have to copy the circuit of the already existing line-in input and wire it into the tape deck input.But before I risk blowing up the audio selector chip I would really like to understand what the input circuit is actually doing (marked in red in the attachment). It would be great if somebody could point me in the right direction as I only have some basic electronics knowledge. I'm guessing it's input attenuation + some kind of filter. I am also wondering if I have to disconnect the tape deck audio lines before wiring in the new input.Thanks

author: Paul Price
author_rank: Super Contributor
timestamp: October 07, 2015, 01:08:18 pm
content: You would be better off using a CMOS analog switch to multiplex the existing input.CD4066BE is a good choice.Or use a dual op-amp to mix the two signals, if this is acceptable, assumes one input is inactive.The circuit in red is simply a resistive divider, an input protection/attenuator with small caps to attenuate/filter out unwanted higher than audio frequencies and avoid the possibility of a high voltage transient applied to the inputs would damage the chip this circuit is feeding.

author: Balaur
author_rank: Unknown
timestamp: October 07, 2015, 01:30:22 pm
content: Yes, it should be safe if you just duplicate the MD/video input circuitry and use that to drive the Tape TCLCH//TCRCH inputs on the selector chip.However, after looking at the attached schematic and after browsing a bit through the service manual, I wonder if there is a mute control for the tape input.I think that you should check this before doing any modifications. Try to inject a signal on the tape channels and see whether the signal is amplified when the tape isn't playing.
Need help figuring out a circuit - Page 1
Forum section: electronics / beginners

author: miksius
author_rank: Newbie
timestamp: December 30, 2020, 09:00:25 pm
content: So a friend of mine has a regad m3000 fileteuse machine. It basically heats resistive wiring at its handle tip.He sent me some pictures of the inside of his machine, because he wants to add a second handle to it.So I'm trying to figure out what is the complete circuit for this machine, so maybe I could remake it (save 200USD) on it for myself and help my friend out as well.So far what I figured out or at least think what it does, is it has mains coming in to a voltage regulator circuit, my guess its sortof like a dimming switch, then the output of it goes to a 220v to 18.3v 48VA transformer to get stepped down. And the secondary coil output gets fed straight into the heating handle. My guess is that the machine in idea sortof operates like those foam cutters that use resistive wire.My question is, am I close or am I too far off from understanding how this circuit works. As well as I'd like to be corrected if I'm wrong that you can indeed drive resistive wire with AC.Pictures of the inside of the machinehttps://imgur.com/a/IFf5d1p

author: S. Petrukhin
author_rank: Super Contributor
timestamp: December 30, 2020, 09:44:08 pm
content: You have understood the scheme quite correctly. But not necessarily a bulky transformer, you can use any adjustable power supply. For example, the simplest laboratory from chinese comrades for $30-50. For example, this:https://aliexpress.ru/item/1005001567403618.htmlor like this - it has 3 memory cells that are convenient to use to save 3 convenient pen glows:https://aliexpress.ru/item/1005001720351801.html

author: S. Petrukhin
author_rank: Super Contributor
timestamp: December 30, 2020, 09:52:26 pm
content: Or even cheaper, similar to this 3-24V 3A:https://aliexpress.ru/item/4000117615953.html

author: S. Petrukhin
author_rank: Super Contributor
timestamp: December 30, 2020, 09:57:05 pm
content: But do not forget that an AC voltage of 18V corresponds to a DC voltage of slightly less than 13V.
Need help figuring out double coil DPDT relay - Page 1
Forum section: electronics / beginners

author: MatCat
author_rank: Frequent Contributor
timestamp: April 07, 2018, 02:55:09 am
content: Greetings,I am looking at relay KEMET EE2-4.5TNUhttps://www.digikey.com/product-detail/en/kemet/EE2-4.5TNU/399-11050-5-ND/4291116It is a double coil dpdt, my problem is I can't make heads or tails of how the pinout works...Which 2 pins are the common poles? (I am guessing 4 and 9?) If that is the case then the default reset position is that 9 will be connected to 10 and 4 to 3? And set position would be 9 to 8 and 4 to 5?

author: MatCat
author_rank: Frequent Contributor
timestamp: April 07, 2018, 02:56:48 am
content: Secondary question, are the ratings per pole or in total? I.E. 125VAC at 0.5A, does that mean 0.5A per pole, or 0.25A per pole?

author: Cerebus
author_rank: Super Contributor
timestamp: April 07, 2018, 03:40:57 am
content: Reset position 4=>3, 9=>10, set position 4=>5, 9=>8.The ratings are for the contacts, so for each contact (when made, obviously).Ratings are: carry 60W or 125VA, maximum switching voltage 220Vdc, 250Vac, maximum switching current 2A, maximum carrying current 2A. You have to derate so that the contact (current, voltage, power) all stay below their respective maxima. e.g. You can switch and carry 2A, but the 60W limit means that doing that you'd be limited to 30V, change to 1 amp and you can switch 60V, go all the way to 220V and you're limited to 270mA.For long life it is a good idea to be very conservative about derating, especially make/break DC current. I'd also treat that reactive power specification (125VA) with caution and err on the safe side. Personally I wouldn't want 120W running through that tiny relay (two will fit on my thumbnail) even if the specs say that you can in theory. These were designed as signal relays and it'd be safest to treat them as such.There is a huge 52 page manual for this range of relays under the title " MINIATURE SIGNAL RELAYS EC2 SERIES (DIP TYPE) EE2 SERIES (SMD TYPE) TECHNICAL DATA" that will tell you more about them than you imagined you could learn.

author: MatCat
author_rank: Frequent Contributor
timestamp: April 07, 2018, 03:49:46 am
content: I agree 120W would be a bit insaneMAX VAC I plan to run in one of these is 10 watts, I am thinking it will be fine for that. I do have the need for another relay that can handle 100W but I planned on finding a better suited one for that separately.
Need help finding a development kit for audio DSP applications - Page 1
Forum section: electronics / beginners

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: August 12, 2015, 09:20:33 am
content: Hi everyoneI want to finally take the plunge into hardware for audio processing. I'm familiar with PCM streams from myfidelify.netproject and I've implemented several VSTs with C++.I've also dabbled with shaders and CUDA so I'm familiar with various mass-parallel concepts.What is the best solution for getting into DSP in the hardware realm? Is there a good quality solution for 'hi-fi' applications (with good integrated DAC and ADC)?Is it better to design my own board with ADCs and DACs to my spec and maybe a FPGA (never used those either..)?Any and all help is much appreciated, thank you!

author: helius
author_rank: Super Contributor
timestamp: August 12, 2015, 09:39:31 am
content: maybe take a look athttp://www.xmos.com/products/boardsfor parallel DSP development boards.

author: coppice
author_rank: Super Contributor
timestamp: August 12, 2015, 10:13:02 am
content: Without some clue about the kind of processing you want to do its really hard to say what is appropriate. What is usually appropriate is to develop everything you possibly can on a PC, where development and debug is very easy, and high quality ADC and DAC interfaces are readily available. When you get your algorithms sorted out you can then look at the MIPS they require, and make a sensible choice about target hardware.

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: August 12, 2015, 10:53:23 am
content: Thank you both!I want to do phase-linear FIR processing, the purpose is room correction in a 7.1 surround setup.And the odd guitar effect and other experiments. Most of which I could do on any mcu with sufficient clock frequency.What this means I guess is that I prefer clock speed over parallelism and DAC/ADC over other peripherals.I will definitly check out the xmos stuff @helius

author: markseel
author_rank: Newbie
timestamp: November 16, 2017, 10:52:05 pm
content: Take a look at this ...https://github.com/markseel/flexfx_kit/blob/master/README.md

author: b_force
author_rank: Super Contributor
timestamp: November 16, 2017, 10:57:00 pm
content: Fur USB interfacing XMOS or CMEDIA.For dedicated DSP's I would recommend SigmaDSP (ADAUxxxx)For just some simple filtering you can use even a PCM5242 (or similar).Some of them you can even connect to a RaspBerry Pi