hybridfree/eevblog-posts huggingface dataset:
minimal/cheap VCO (20hz - 22Khz) - Page 1
Forum section: electronics / beginners

author: xchip
author_rank: Regular Contributor
timestamp: July 07, 2013, 12:15:13 pm
content: Hi guys,I recently built an ECG(http://codinglab.blogspot.be/2013/07/my-heartbeat.html) and I can successfully display my heartbeat wave on my PC. Now I'd like to record that wave on my phone on the cheap, I thought about converting that wave into a frequency and feed that thought the mic jack, then on the phone I could just recover the value using software...I'd like it to be portable, small and low power... I hope I am not asking for too muchAny ideas?Thanks! O0

author: c4757p
author_rank: Super Contributor
timestamp: July 07, 2013, 12:36:51 pm
content: Have you considered using a small MCU with a fast-ish ADC to make a makeshift modem?

author: Rerouter
author_rank: Super Contributor
timestamp: July 07, 2013, 12:45:37 pm
content: i myself kinda have to agree with a dirt cheap micro with a built in adc and an AD9850, cheap as chips, bugger all external components, and that ad9850 handles extremely low frequencies very well,

author: xchip
author_rank: Regular Contributor
timestamp: July 07, 2013, 01:14:57 pm
content: I just want a VCO goes from 0 to 5volts and that covers all the audible range, using a PWM from a MCU sounds reasonable, no need for the AD9850.

author: c4757p
author_rank: Super Contributor
timestamp: July 07, 2013, 01:16:00 pm
content: If the data rate is low enough, you should be able to get away with direct square wave output and ignoring harmonics in the receiver software.

author: JackOfVA
author_rank: Unknown
timestamp: July 07, 2013, 02:25:32 pm
content: The classic analog approach would be something like an XR2206 integrated circuit (Jameco has them in stock, didn't look beyond that.)However, I would re-think the idea of 20 Hz - 20 KHz frequency span. Something like a center frequency of a few KHz with a span of a few KHz makes more sense. For example, center frequency 10 KHz, and modulating span of 5 KHz so the frequency range is 7.5 - 12.5 KHz will be much easier to build and operate with decent linearity. (The 0-5V input maps to 1 Hz/mV.)The matching analog decoder chip, by the way, is an XR2211, also available from Jameco.

author: profmason
author_rank: Contributor
timestamp: July 07, 2013, 02:39:33 pm
content: Off the top of my head, cheapest vco is a lm324 see data sheet limited to 7 khz. Simple cheap vco is 555 timer in astable mode with pin 5 tied to voltage input. Read data sheet. More pro solution is a 4046 vco pll or 2206 vco.However, better solution might be just feed output signal into Schmidt trigger and read digital pulses on phone. Otto Schmidt developed the trigger for ecg applications in the fifties.

author: Andy Watson
author_rank: Super Contributor
timestamp: July 07, 2013, 03:06:31 pm
content: Quote from: xchip on July 07, 2013, 12:15:13 pmCan you not save the waveform on the PC? Manipulate it in software and then output a wav, or mp3 or whatever dings your dong.
Minimum ground copper pad size for power loss - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: May 18, 2021, 02:45:55 pm
content: 1. One switcher shows that max power loss is 4W at peak load (https://www.analog.com/media/en/technical-documentation/data-sheets/lt8645s-2.pdf) , page 1, figure 2.2. Now I have to design its ground pad on botton layer while this IC is on top layer. How much gnd pad for heat sink I have to give so that maximum temperature rise goes upto certain degree let say 50C ?3. Assuming copper thickness is 2oz for PCB design.4. tried seraching but this shows up, its entirely different thing :https://www.4pcb.com/trace-width-calculator.html

author: jmelson
author_rank: Super Contributor
timestamp: May 18, 2021, 04:26:13 pm
content: There's no simple answer. First, if the pad is on the opposite side of the board from the heat source, it won't do much. The PC board substrate (fibherglass) has about 1000 X the thermal resistance of copper. You can solve that by lots of vias. Second, the thermal pad will have to conduct heat to the environment. Will there be a case over the board?That blocks the heat removal. 4 W is a LOT of heat to radiate/conduct from a PC board alone.Jon

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: May 19, 2021, 04:02:22 am
content: I can made dissipation pad both on top layer and bottom. Would remove green masking from both top and bottom layer. But how much pad size calculation is a question

author: Momchilo
author_rank: Regular Contributor
timestamp: May 19, 2021, 11:23:06 am
content: I calculated something similar for MOSFETs with high currents.There is no way to dissipate 4W from a PCB alone. You have to add some heat sinks on the backside with many vias or on top of the chip.There are some papers with good estimations. For example:https://www.onsemi.com/pub/Collateral/AND9596-D.PDFHere it is explained more simply:https://www.pcbcart.com/article/content/pcb-theraml-design.html#:~:text=a.,C%20rise%20in%20board%20temperatureThey mention 15cm² per Watt. But it depends on many factors like the number of layers.

author: bobbydazzler
author_rank: Regular Contributor
timestamp: May 20, 2021, 03:06:53 pm
content: fr4 radiates heat better than copper. I would just leave enough pad exposed with a lot of vias to conduct heat to place a heatsink on. 4w definitely needs a heatsink.
minimum pcb track width for them to be more durable - Page 1
Forum section: electronics / beginners

author: amateur_25
author_rank: Regular Contributor
timestamp: May 15, 2014, 05:01:45 pm
content: HiI made a pcb for an led matrix to use as a diy uv exposure box. But the pad and traces are EXTREMELY FRAGILE!!I find when am soldering the leds in, the traces get seemingly burnt off the board (350 C temp). or pads were damaged in the drilling process.There will be nothing but bare board where my soldering iron was.I have done several strip board prototypes and NEVER had a problem with copper lifting off. Why is it so easy to damage pcbs made out of copper clad board? The same goes with the cnc machine we use to mill pcb. Is there a minimum track width I need to make them more durable? Any advice would be appreciated since this is driving me up the wall.

author: brabus
author_rank: Frequent Contributor
timestamp: May 15, 2014, 05:11:57 pm
content: I guess we need more infos.Which substrate do you use, vetronite or bachelite? I remember to be forced to use bachelite when milling my boards, to avoid excessive wear of the drill bits: the final quality of the PCB was so poor that I abandoned milling in favor of slower (but better) prototyping services, like OSHpark.Other important factor: the quality of your substrate: maybe your boards have too much moisture inside, and need to be baked before processing them.General rule of thumb? Well, for bachelite boards I never went under 20 mils (!), both for trace width and trace spacing. With vetronite I tried to push a bit more, reaching 15 mils, but I never trusted those thin traces so much.For sure you can reach better goals, but it's always a risk.Better stay safe, or change your technology.p.s.: Do you use your own milling machine?

author: SArepairman
author_rank: Frequent Contributor
timestamp: May 16, 2014, 05:49:36 am
content: is it possible to mill "scoring" the copper, so that it is thin in certain areas, but not touching the abrasive substrate, and then do a quick etch, a combined process to save on bit wear and minimize exposure to etchant?i imagine it might be hard with ductile copper though

author: sleemanj
author_rank: Super Contributor
timestamp: May 16, 2014, 06:17:02 am
content: Part of the problem is that on a home etched board you've usually got no solder mask which can help "glue the traces down".End of the day, make the pads, and traces, as big as you can.Don't forget that (assuming your software can) you don't have to have round pads for through holes, you can make them oblong to radically increase the footprint of the pad (and thus bond area to the substrate) while maintaining the clearance pad-to-pad.I try to make round pads a MINIMUM of 1.5 mm diameter with 0.8 mm hole, (0.362 mm ring thickness therefore), you might also make these oblong out to 2.2 mm by 1.5 mmIndeed, a lot of standard foot prints, especially for SMD, are best modified to aid hand-soldering, just adding 0.1 or 0.2 mm extra length on a pad can make the difference between easy-to-solder and a lot of faffing about.
minimum PS voltage and current for general use - Page 1
Forum section: electronics / beginners

author: SnakeBite
author_rank: Regular Contributor
timestamp: November 28, 2010, 08:47:25 am
content: Hello,i want to buy a bench PS soon, but i don't know what is the minimum recommanded voltage and current that i sould buy.i almost sure i need more that 12v because a lot of electronics components works with this voltage.i thought about a TDK-lamda LQ-531 with 20v and 8.6A what to do think? is it enough?thanksIdo

author: arcom
author_rank: Contributor
timestamp: November 28, 2010, 09:12:10 am
content: That depends on your definition of "general use". Someone who works with opamps on a daily basis requires a dual 0-15V PSU whereas someone who works mostly with digital logic requires stable 3,3/5V PSU.0-25V @ 2A should cover 99% of power requirements for most hobby work.To be on a safe side, dual 0-25/30V @ 3A is most popular choice if you can afford it.

author: SnakeBite
author_rank: Regular Contributor
timestamp: November 28, 2010, 10:54:35 am
content: which one of the lambda series will be best for me:i can't decide between the LQ-531(20V @ 8.6A) and the LQ-532 (40V @5A)http://www.teknetelectronics.com/DataSheet/Lambda/Lambd_LQSeries23956.pdfCAN YOU HELP ME?

author: saturation
author_rank: Super Contributor
timestamp: November 28, 2010, 01:46:25 pm
content: HiYou asked this question on another thread before I recall. Lambda is a top notch, and expensive PSU. These are great for professional work when you really have these going everyday; then you also compete with the likes of Agilent's PSU.For hobbyist use they are overkill.Generally, up to 25-30V at 3A is fine, these are the upper end for used on analog designs with op amps, and for most needs, you need a dual. So you need either a single dual supply or two 30V supplies you can use together when you need it.I prefer 2 separate, so if one blows, you still have the other working.Quote from: SnakeBite on November 28, 2010, 08:47:25 am

author: SnakeBite
author_rank: Regular Contributor
timestamp: November 28, 2010, 05:10:19 pm
content: I know it's OVERKILL that why i want it! i'm a professional on bringing the top marker product at very affordable prices. look at my other posts...for example : i got FLUKE 87V in 180 $ with shipping included to Israel, instead of 350$ + shipping. i also got the PACE MBT 250 in 130$ shipping included instead of 1200$ + shipping.and so on....got the pointIdo

author: Psi
author_rank: Super Contributor
timestamp: November 29, 2010, 11:32:06 am
content: Love my lambda MML400, got it for NZ$100 secondhand.It's not really a lap psu tho, no setable current limit. I just use it when i need high voltage or high current that my normal lab psu cant do.It came with 4 isolated modules so there's a huge number of ways to connect them up for anything from 2V @ 25A to 70V at 6A
minipro asks for firmware update but cannot find it for the life of me - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: October 04, 2020, 02:35:37 pm
content: Hi,I purchased (long ago) a tl866ii plus, and I started using it now with my mac via theminiprolibrary.All is good but when I try and upload my hex files, a warning is issued:Code:Found TL866II+ 04.2.86 (0x256)Warning: Firmware is out of date.Expected 04.2.105 (0x269)Found 04.2.86 (0x256)I tried searching on the internet but was unable to find the firmware. Anyone can tell me where to find it?Sorry if it's a stupid question

author: greenpossum
author_rank: Frequent Contributor
timestamp: October 04, 2020, 03:11:53 pm
content: Have you tried the manufacturer?http://autoelectric.cn/EN/TL866_main.html#Sorry I have an older model so I can't verify the firmware version.

author: Moriambar
author_rank: Unknown
timestamp: October 04, 2020, 04:04:44 pm
content: Quote from: greenpossum on October 04, 2020, 03:11:53 pmyup, I tried, but I can only find a link to the windows software plus some unrelated stuff
MiniPro TL866 newest Firmware/Software/Devicelist - Page 1
Forum section: electronics / beginners

author: jaybee
author_rank: Newbie
timestamp: September 25, 2025, 12:55:23 am
content: Hi,i own an old MiniPro TL866CS patched to an A.Now i want to Clone an MX25L25635FMI-10G.It is listed in the Devicelist at the Website, but i cant find it at my Device.It showas App 6.85 Firmware 03.2.86.My Devicelist shows a lot of MX25L128, but no 256.How can i get an actual Devicelist/Firmware/App?TIAJay
MIP005 datasheet (SMP IC) - Page 1
Forum section: electronics / beginners

author: Jan Catrysse
author_rank: Contributor
timestamp: December 27, 2020, 01:49:48 pm
content: Hello, does anyone know where to find a datasheet for a MIP005 IC? It's commonly used on switch mode powersupply boards (for laserprinters and such).It's readily available on ALIExpress, but I can't find any datasheet or an alternative from an A brand.Apparently it's made by Panason, but I can't find much on them.Thank you.Jan

author: m k
author_rank: Super Contributor
timestamp: December 29, 2020, 05:45:33 pm
content: Last page of MIP0060ME manual has an interesting disclaimer.https://www.datasheetarchive.com/MIP006-datasheet.html

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: December 29, 2020, 06:08:33 pm
content: Probably pin compatible to this:https://industrial.panasonic.com/content/data/SC/ds/ds4/MIP0060MXL_E.pdf

author: Jan Catrysse
author_rank: Contributor
timestamp: December 29, 2020, 09:30:13 pm
content: Thank you! I think it is, great!
MIP166 silicon mos IC help needed  - Page 1
Forum section: electronics / beginners

author: efan
author_rank: Newbie
timestamp: June 20, 2024, 07:21:04 pm
content: I have downloaded the data sheet and it refers to component as a intelligent power devices silicon mos ICI have tested it in my LCR meter and shows as a diodeI though this was a simple transistor but turns out it's a component thats going to be impossible for me to test without some special equipment thats my question is this component failed or what would be the best way to test it.It was taken out of a power supply that was not giving correct readings and i am trying to diagnose this component is right after power input into inductors and protections capacitors i suspect this is faultyI have included the data sheet if anyone want's to be bamboozled by the block diagram

author: rkabz
author_rank: Contributor
timestamp: June 21, 2024, 11:35:00 am
content: Explain 'not correct readings? How about a pic of the power supply board. Likely another component has failed.

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 21, 2024, 11:53:37 am
content: This is an integrated primary switcher for flyback converter, of course those simple testers will only detect its body/substrate diodes.Please note that this components handles lethal high voltages. Please reconsider whether you're comfortable messing with this. From your description I'm not convinced with your ability.Also if your PSU still output some voltage, it might be just a fault on the secondary side feedback circuit. Primary side fault tend to be either catastrophic or fully dead outputs.

author: efan
author_rank: Newbie
timestamp: June 21, 2024, 12:44:55 pm
content: Yes i agree that this is a a dangerous power supply and i have taken the proper safety precautions and understand the dangersObviously i have taken readings and then discharged capacitors before handling it.I know more about safety than the components i am working with as every project is new data sheetsThis is a fostex 1624 mk2 very rare multitrack recorder it was working perfect i put it away in a rack case and when one day i switched it on there was no power to display ''vacuum fluorescent displays'' On inspection i found a tiny pcb that outputs power to the display had 1 blown ferrite smd.So this has been a work in progress and have been checking every component on PCB but juss discovered no continuity on F1 TR5 fusewhy is there no information i can find on how to check this fuse has failed on the internet i assume it's no continuity so it is bad
MIPI DSI Connector - Page 1
Forum section: electronics / beginners

author: enitalp
author_rank: Newbie
timestamp: April 28, 2022, 01:30:18 pm
content: Oh boy, for my current project I entered the deep well that is the LCDs.So I'm making a board to test all those interfaces and protocols, that my microcontroller can do.And I really need to connect to a 2x15 pins MIPI screen, like on the raspberry pi, pitch 0.5,But I can't put my mouse on this stupid connector or its nameall I know is it's a 2x15 pin ribbon with a pitch of 0.5mm if somebody can point at me in the right direction. ThanksExtra friend point if it's a link tohttps://www.lcsc.com/or Digikey or mouser and that's in stock ;p

author: ve7xen
author_rank: Super Contributor
timestamp: April 28, 2022, 11:49:31 pm
content: AFAIK there's not really a 'standard' per se, but the Raspberry Pi uses a 1mm pitch, 15 pin FFC connector. The standard FFC thickness is 0.3mm. It should be easy to find on any parametric search at DigiKey or LCSC or whatever. Lots of styles, depending on what orientation, whether you want locking and so on.Here's a vertical-launch one at LCSChttps://www.lcsc.com/product-detail/FFC-FPC-Connectors_HDGC-1-0K-GT-15PB_C2915527.html

author: enitalp
author_rank: Newbie
timestamp: April 29, 2022, 01:01:27 pm
content: Thanks a lot, found his brother, the 2x15, not simple when it come to precise connector on circuit.Too much choice and name ;p
Missing pin 1 mark - Page 1
Forum section: electronics / beginners

author: Raj
author_rank: Frequent Contributor
timestamp: June 23, 2021, 07:41:14 am
content: Did I get a fake from China?The lm75 I've ordered lacks pin 1 markingGood thing, I've got a lot of them, so i can burn one of them testing the pinoutI'm guessing, it's the down right one in the pictureThe tech drawing of the datasheet clearly shows a pin one mark

author: Jeroen3
author_rank: Super Contributor
timestamp: June 23, 2021, 07:55:52 am
content: Check if one side of the package may be chamfered. That is the your pin 1 side.Datasheet also mentions this though, yours must be old.https://www.nxp.com/docs/en/data-sheet/LM75A.pdfAlso, your screenshot is of the TSSOP8, and it seems you actually have the SO8.

author: Raj
author_rank: Frequent Contributor
timestamp: June 23, 2021, 08:03:30 am
content: yes it is. now there's some doubt gone.Strange new fangled way of marking pin 1 though.And indeed... got the package type mixed up while reading the datasheet

author: tooki
author_rank: Super Contributor
timestamp: June 23, 2021, 12:40:51 pm
content: Quote from: Raj on June 23, 2021, 08:03:30 amNot newfangled at all. It’s one of the established methods. If anything, one that’s fallingoutof favor as the packages get thinner, leaving no height to be chamfered.

author: amyk
author_rank: Super Contributor
timestamp: June 23, 2021, 01:28:02 pm
content: With the text in normal orientation I don't think I've ever seen pin 1 on an inline package be anything but the bottom left corner.

author: gcewing
author_rank: Regular Contributor
timestamp: June 25, 2021, 09:33:49 am
content: The chamfer might be designed for detection by machines.

author: tooki
author_rank: Super Contributor
timestamp: June 25, 2021, 10:46:32 am
content: Quote from: gcewing on June 25, 2021, 09:33:49 amDoubtful. This marking type was never universal enough to serve that purpose. Orientation-sensitive SMD components are always oriented the same way in the reel.

author: redben
author_rank: Contributor
timestamp: June 25, 2021, 12:34:29 pm
content: Agreed, I have not seen any new components from major manufacturer using this chamfer solution.
Mystery inductor [SOLVED] - Page 1
Forum section: electronics / beginners

author: newbrain
author_rank: Super Contributor
timestamp: February 19, 2018, 03:01:22 pm
content: I'll resort to the collective knowledge of the forum.I've been given some SMD inductors (see bad phone picture, actual size about 2x2x2mm), but I cannot really read the colour code.Google is not my friend, I was not able to find any similar inductor.How many bands am I supposed to see?Two brown - one black - one silver? 11 * 0.01 = 0.11uH? Or what?Smashing one confirms that they are actually inductors.Tonight I'll try to see the LC resonant frequency with a known capacitor...

author: Belrmar
author_rank: Regular Contributor
timestamp: February 19, 2018, 08:18:36 pm
content: For this kind of stuff the best way to know a value is the LC resonance, if you are looking for a precise value SMD inductors are not the best they usually come with 20% tolerances, so yes. LC FTW

author: newbrain
author_rank: Super Contributor
timestamp: February 19, 2018, 08:22:56 pm
content: Thanks,That's what I plan to do. I also have some with two thin red lines plus the brown one...It will stay a mystery till tomorrow, though, as I forgot them at workEdit:Mysspelling in the thread title

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 19, 2018, 10:59:01 pm
content: 91? 221 (for the other)?Anyone's guess if that's nH, uH or something else. Coilcraft parts for example are numbered from a variety of decimals, so you have to look at the datasheet (not that the number is normally printed on the part anyway, so you have to measure anything salvaged).Tim

author: newbrain
author_rank: Super Contributor
timestamp: February 20, 2018, 09:12:19 pm
content: Well the are quite small, if they are inductors at all.With 47nF Fres~=3.6MHz.So, that would be about 40nH...too close to the self inductance of a few cm of wire to be confident in the result...

author: newbrain
author_rank: Super Contributor
timestamp: February 23, 2018, 07:54:22 pm
content: Ok, I made a tighter test rig and got more reasonable results.They are read from the wide color band, 3 bands only.Value is in nH.The one in the photo in the OP is Brown - Gray (or white?) - Black = 18nHFrom the first screenshot, still with 47nF ~22nHThe other one Brown - Red - Red = 1200nHFrom the second screenshot, 47nF ~ 1300nHConsidering tolerance and parasitic L/C, a good match.
Mistery signal in my poweline - Page 1
Forum section: electronics / beginners

author: mio83
author_rank: Regular Contributor
timestamp: June 08, 2021, 07:21:25 pm
content: Hello,today with my new oscilloscope, I wanted to check the noise of my power supply (a TTi EL301R, which should be quite nice).I noticed that, while generally very low noise, from time to time there was a burst of activity.It turned out that this bursts occurred even with the power supply OFF!In figure 1 you can see one of these bursts (with power supply OFF, and scope leads connected to the + and - of the power supply):As you can see, the burst lasts about 0.5ms and has is of about 250/300mv peak-to-peak.In figure 2 you can see a zoom on the burst:The signal is composed of two parts:1) the first part (delimited by the cursors) lasts about 80us. This part is always fixed because at each trigger event it looks the same.2) the second part, where it seems there is some kind of message.In figure 3 you can see a zoom on the 2nd part, i.e., the "message":It looks as some kind of fm/phase modulation. With the cursors I have delimited one cycle having frequency 20Mhz.QUESTION: Do you have any idea what this could be? It seems like some kind of messaging going on? I tried to turn off all the power supplies around my bench but the signal still persists.Thanks!

author: mio83
author_rank: Regular Contributor
timestamp: June 08, 2021, 07:49:38 pm
content: Mistery solved!!!After turning off basically everything in my apartment, I remembered that to connect my smart TV to my internet router I use a mains-adapter, that sends data through the electric line instead of using a proper Ethernet cable!I am very happy with my new digital oscilloscope! I never saw this before with my old analogue oscilloscope!
Misunderstanding Mosfets - Solenoid Driver? - Page 1
Forum section: electronics / beginners

author: kazzle101
author_rank: Contributor
timestamp: November 26, 2019, 09:04:30 am
content: HelloI want check I'm doing this right, and that I'm not being daft thinking the smaller SOT-23 mosfet will be suitable.I am wanting to drive a few 12V 2.5W solenoids using an Arduino clone - Teensy 3.2, that runs 3v3 logic. The solenoid draws about 420mA at 12V when on.Looking trough my box of stuff I have found two N-Mosfets that seem to do what I want:SI2338: Max: 30V at 6A in a SOT-23 packageSTD25NF: Max: 100V at 25A in a D-PAK packageNow I've always believed that to switch the transistor fully on, I should look for the Gate Threshold Voltage Vgs(th) and that this should be below that being used on the Gate - the 3.3V logic. For the SI2338 this is Min:1.2V, Max:2.5V and the STD25 Min:2V, Max:4VI've made up the circuit on breadboard as in the badly drawn diagram, and switched between the transistors. Both appear to perform equally well, the solenoid clacks on and off as expected, nothing gets warm and on my cheap oscilloscope the signal looks square, I can't see any ramping.Am I OK to use the SI2338? Or have I missed something?Datasheets:SI2338:https://www.vishay.com/docs/67877/si2338ds.pdfSTD25NF:http://www.farnell.com/datasheets/1689940.pdfThanksKarl.

author: aheid
author_rank: Regular Contributor
timestamp: November 28, 2019, 03:03:07 am
content: The SI2338 should be fine. You'll want a max threshold voltage that's significantly lower than your drive voltage. Since you only need it to pass some ~0.5A, you can cut a bit closer.Look at the first plot on the page of plots, I_D vs V_DS. At 3V V_GS it's fairly limited how well it conducts, while the higher V_GS values cause it to saturate at far higher drain currents.Compare with the same plot for STD25 (figure 3). The lowest curve is for 4V V_GS and shows it saturating at less than 2A. Given that you'd drive it at 3.3V you can see how marginal that would be.

author: Psi
author_rank: Super Contributor
timestamp: November 28, 2019, 03:07:43 am
content: Looks fine to me too
Misunderstanding of data sheet of photodiode C30954EH - Page 1
Forum section: electronics / beginners

author: ggeorgiev
author_rank: Contributor
timestamp: June 08, 2023, 05:15:37 pm
content: Hi all,I am a bit confused about the datasheet of the photodiode C30954EHhttps://www.excelitas.com/de/de/file-download/download/public/60161?filename=Excelitas_Si_APD_C30954EH_datasheet.pdffrom Excelitas.As shown in the picture below, they have written Anode (Negative Lead) and Cathode (Positive Lead). But isn't that actually wrong?Isn't the anode usually always the positive lead and the cathode the negative one?Or why have they written it that way?Thanks in advance for the help!" alt="" class="bbc_img" />

author: ataradov
author_rank: Super Contributor
timestamp: June 08, 2023, 05:46:25 pm
content: The diode itself does not have "positive" or "negative" side. Photodiodes are typically operated in a reverse-biased configuration, so I guess they stressed this fact by marking C and A that way.

author: ggeorgiev
author_rank: Contributor
timestamp: June 08, 2023, 06:09:16 pm
content: Quote from: ataradov on June 08, 2023, 05:46:25 pmI want to use the diode in a reversed-biased configuration. So connecting it as shown in the picture below, basically Anode and Case to the ground and Cathode to the negative input of the OPAM, must be correct. "Without being confused by negative and positive.."

author: ataradov
author_rank: Super Contributor
timestamp: June 08, 2023, 06:12:46 pm
content: Yes, this is the typical connection. So, go with the Anode/Cathode nomenclature and ignore those "helpful" notes.

author: RoGeorge
author_rank: Super Contributor
timestamp: June 08, 2023, 06:17:45 pm
content: Anode (the arrow side of the diode symbol) and Cathode (the bar side of the diode symbol) of any diode are dedicated terms. 'Positive lead' and 'Negative lead' are ad-hoc terms, probably used to denote that the photodiode should be kept polarized in reverse in the detection circuit.

author: RoGeorge
author_rank: Super Contributor
timestamp: June 08, 2023, 06:23:22 pm
content: In the schematic you posted both the anode and the cathode of the diode are connected to the same potential, the signal ground, because the positive input of the opamp is also at the signal ground. A and B inputs of the opamp are at the same potential.To polarize the diode in reverse, you'll have to keep the in+ of the opamp at a higher potential than the anode of the diode.
MIT Circuits and Electronics online course started again - Page 1
Forum section: electronics / beginners

author: Kappes Buur
author_rank: Regular Contributor
timestamp: October 28, 2013, 09:17:55 pm
content: May be of interest for somehttps://www.edx.org/course/mit/6-002x/circuits-and-electronics/1130It's a 17 week course.Started a week ago.Prerequisite: some calculusParticipation is not required, course can be audited.
Mitigating ESD through hotswap connector without chassis ground connection - Page 1
Forum section: electronics / beginners

author: t12
author_rank: Newbie
timestamp: October 10, 2024, 02:17:57 pm
content: Hello all,Edit: Changed title cause I read it back and was rubbish.Currently working on a project, learning a lot as I go. Been reading/skimming the Henry Ott EMC book for answers but my problem is going outside my intuition.Have attached a picture of the layout and have the following questions, any insight would be appreciated.Key points:-Designing a hot swap enclosure which fits into a larger grounded chassis.-Don't have much/any control over the host enclosure-The connector between systems does not have a good exterior electrical connection - I could dedicate a couple of pins for connection to chassis ground, but the isolation between this and other signals would be poor (100v), also cannot be sure whether the host system would sensibly connect it to chassis or if it would just connect to system ground regardless.-I'm trying to rationalise how an ESD fault current would flow from the exterior of the hotswap chassis back to host earth connection-Power rails and IOQuestion:-How should I provide a ESD path to the enclosure with minimal chance of disruption to device/host?Option A: Provide direct connection from chassis to ground plane as near to connector as possibleRationalisation: Low impedance/but not particularly low inductance, full ESD current go through ground and may/may not go through chassis on host side of connectorOption B: Connect a TVS diode or something else (e.g. surge resistor) between chassis and system groundRationalisation: I thought this might help dissipate some energy, but on further thought it probably doesn't, since almost all of the voltage would be seen on ground anyway, regardless of the orientation of the diode. A resistor would loosely couple the grounds and seemingly should reduce the ESD current, but I'm not sure how this would affect the ESD path and/or safety.Option C:Pseudo isolated grounds, splits, opto isolators, chokes, filters?thanks in advance...
Mitsubishi MBE90K Sensor Adjustment - Page 1
Forum section: electronics / beginners

author: bigpappy
author_rank: Newbie
timestamp: May 14, 2015, 04:39:12 am
content: Hello all, I must start out by saying that as a mechanical engineer I am out of my element over here so please don't mind any silly questions.Long story to follow, I own a small machine shop and my CNC turning center is having some threading feedback issues.I've already been on the phone with the manufacturer, Mazak, and they handed me off to Mitsubishi Electric Automation as it is their "package" that is out of whack.This "package" or the MBE90K consists of two gears, two sensors, and a pre-amplifier, all of which control the C-axis, speed feedback, and spindle orientation.After speaking with a tech, we were able to narrow my issues down to the pre-amp and I was able to get a step-by-step adjustment manual from them.Basically, I needed to adjust the waveforms of each pulse and phase to match the stock configuration and be within the required tolerances.For example my threading issue has to do with the X-pulse which is for orientation."The pulse width of the X-pulse needs to be 65-75% of the period of the F-phase. The rising edge of the X-pulse needs to rise before the start of the F-phase sine wave. The distance between the rising edge of the X-pulse and the start of the F-phase needs to be 5-10% of the period of the F-phase...."This is all adjusted with multiple little knobs on the board.This all sounded a bit out of my league and I do not have oscilloscope at my disposal so I had a private tech come out to do the adjusting.Well he adjusted everything right at the edge of the allowed tolerances, so once the machine heats up and gets rolling, the tolerances get blown and the pre-amp sends jumbled signals to the controller.For the cost of him to come out again I can purchase the Rigol DS1054Z or equivalent and be money ahead.My question is, how do I know what bandwidth I need on the o-scope to measure and adjust the pre-amp properly, i.e. I don't want to buy more than I need, but also don't want to get stuck with something that won't work.I asked Mitsubishi that question and they had no idea, he said they just use some high end expensive fluke to do everything they need.No mention of specs or model numbers.From some of the research I've done, it seems the frequency of the circuit being tested is usually a known variable before starting.What are you supposed to do for completely unknown circuits?I apologize for the long winded post, but I figured I would give you the whole story!Thanks in advance for any help.

author: wraper
author_rank: Unknown
timestamp: May 14, 2015, 08:44:15 pm
content: If it drifts while heating up / over time, I suspect there might be some fault. Therefore repair might be needed, not adjustment.
Mixed signal basic design - noise considerations - Page 1
Forum section: electronics / beginners

author: mcdesca
author_rank: Contributor
timestamp: May 17, 2015, 11:04:48 am
content: Dear everybody,I did a small design with a pretty basic mixed signal modules: a microcontroller will generate a signal by means of a DAC (MCP4821) and then amplified and fed to the power mosfets. Some analog feedback signals through opamps are being then fed to the uC's ADC. The power supply will be done by means of switch mode dc/dc converter.A first design works just fine but i guess I've payed too little attention to the pcb layout and hence, I've got some noise mainly, in the DAC output. Since all the software and hardware functionality have been proven, I'd like to redesign the layout in order to achieve good signal quality.Attached is my first module organisation which in some way, is the way I'll first split the ground planes and interconnect them in one spot.The Current Monitor (INA125) monitors a 0,2ohm shunt resistor and I just want to go to the milliamp resolution. Right now the dc/dc converter is producing some noise in this reading.The DC/DC converter switches at 500KHz (both for the 5VDC and 12VDC channel).I've readen that the opamp become less noisy when in inverting mode (which I haven't foreseen since I don't have a split supply, but can). Is this that bad (I'm using lm358 opamps)?.I kindly ask you for feedback and what your experience on noisy DAC's is.Thanks a lot.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 17, 2015, 05:31:43 pm
content: LM358 will read incorrectly in the presence of RF (input rectification effect), might be relevant?Those cheap current sensors might have similar problems, and don't usually have fantastic CMRR either.Tim
Mixer (product detector) question. - Page 1
Forum section: electronics / beginners

author: firewalker
author_rank: Super Contributor
timestamp: February 01, 2014, 01:05:43 pm
content: Can someone explain how the following mixer works? I know the mathematic aspect of the subject.A really simple circuit to produce the difference of the two frequencies. 10 MHz at the one input 10.001 MHz, 1 kHz after the Low Pass Filter.As I can understand it; the signal F2 is responsible for the biasing of the diodes. The two signal beat each other. Due to the frequency difference the dc offset of the produced signal (the signal at point A) moves up and down following this difference. The low pass filter rejects everything else except this dc bias movement.Am I correct?Alexander.

author: fcb
author_rank: Super Contributor
timestamp: February 01, 2014, 02:12:01 pm
content: It's just a unbalanced mixer (look up double balanced mixer for theory).

author: valentinc
author_rank: Regular Contributor
timestamp: February 01, 2014, 02:45:48 pm
content: The mixer relies on the nonlinear I-V characteristic of the diodes to produce other frequencies (f1 + f2 and f1 -f2)... Since it's an unbalanced mixer, a part of f1 and f2 are also present at the output...The low-pass filter removes f1, f2 and f1+f2 from the output and only passes f1-f2 (which is 1Khz in this case)

author: jimmc
author_rank: Frequent Contributor
timestamp: February 01, 2014, 08:15:41 pm
content: The diodes are used as switches controlled by the local oscillator signal applied to the F1 input.When the F1 input is sufficiently +ve wrt Gnd both diodes are on and the F2 input is connected to 'A',when the F1 input is -ve the diodes are off and there is no connection between F2 and 'A'.The mixer is singly balanced i.e. if the diodes and transformer secondaries are perfectly matched then there is no F1 signal fed to 'A'.Try running your simulation with V1 = say 1v pk and a 50ohm resistor in series to limit the diode current. Use a square wave to make things clearer.V2 should be much lower than V1 (say100mV pk) so that it does not affect the diode currents much.Jim

author: firewalker
author_rank: Super Contributor
timestamp: February 02, 2014, 09:29:25 am
content: Thanks you guys.Alexander.
Mixing 3.3v and 5v CAN transceivers - Page 1
Forum section: electronics / beginners

author: e100
author_rank: Frequent Contributor
timestamp: March 15, 2024, 05:30:51 am
content: Is this scope image typical when mixing 3.3v and 5v CAN transceivers?The left side is the end of a frame is transmitted by a 3.3v device and the ACK bit on the right is sent by a 5v device.(120 Ohm termination resistor, baud rate 250k, cable is 60cm long, grounds are connected.)Does it matter that the bias voltage is being up shifted from 1.9v to 2.5v giving a very unsymmetrical waveform from the 3.3v sender?The 3.3v end is using a (hopefully genuine) SN65HVD230 breakout board from Waveshare which has a soldered termination resistor.The 5v end is an isolated version of the Canable CAN interface USB adaptor from Aliexpress.

author: BennoG
author_rank: Frequent Contributor
timestamp: March 15, 2024, 06:18:46 am
content: This is normal on CAN signals.If you have a lot of members on the bus the ACK will always be far higher than the normal data.P.S. every node on the bus needs to have a isolated power and driver, so you need isolation on both sides.Benno
Mixing AC and DC current modes on a Fluke 87v - Page 1
Forum section: electronics / beginners

author: SirRage
author_rank: Contributor
timestamp: June 05, 2016, 08:23:21 am
content: Hey there,So this sounds like a dumb question but I haven't been able to find an answer to it in the manual or online so far. I was wondering if you would damage the meter if you accidently left the unit in DC current mode and stuck the probs into an AC source while diagnosing another issue. I imagine there is some kind of protection circuitry in there to prevent damage.

author: Simon
author_rank: Unknown
timestamp: June 05, 2016, 08:25:24 am
content: I don't believe it would usually do any damage but your manual should specify maximum ratings for the input. It would however measure 0 V as the average of a perfectly symmetrical AC signal is 0. I have before measured the output of a 9 V AC transformer with the meter set to DC with no problem and then wondered why a capacitor on the output blew up

author: retrolefty
author_rank: Super Contributor
timestamp: June 05, 2016, 10:31:55 am
content: Quote from: SirRage on June 05, 2016, 08:23:21 amThe most common damage mode is to have the meter in current mode (AC or DC) with the probe in the proper current jack and then in error go and attempt to measure a voltage source (AC or DC). That's called a brain fart but the meter will protect itself via it's internal current protection fuse but the external circuit may be damaged by the momentary high current before the fuse opens.

author: Simon
author_rank: Unknown
timestamp: June 05, 2016, 10:45:37 am
content: It shouldn't actually be a problem because the DC mode is made to take current and voltage in both directions which is all AC is. It's just that your measurements are going to be rather wrong.

author: jeroen79
author_rank: Frequent Contributor
timestamp: June 05, 2016, 11:08:43 pm
content: As illustrated by Simon, the biggest risk of accidentally measuring DC on an AC source (or vice versa) is that it may lead you to believe that the source is not live and safe to touch.
Mixing different capacities of Lithium Batteries in parallel - Page 1
Forum section: electronics / beginners

author: jerryk
author_rank: Regular Contributor
timestamp: March 18, 2022, 12:35:20 am
content: I'm doing an autopsy on LiFePO4 battery failure. The packs of are arranged in a bizarre way that I have not seen before.There are two packs in parallel. One is 4S and the other is 4S2P. There is a significant capacity difference between the two main packs. I know you can mix capacities to a degree and I have done it. I usually have some sort of uniformity in the arrangement and avoid such a huge capacity difference. Is this kind of practice normal? Anyone ever seen this done?Jerry

author: BrokenYugo
author_rank: Super Contributor
timestamp: March 18, 2022, 01:26:15 am
content: I don't follow, isn't this no different than 3 4S packs in parallel? The cells look to be the all the same size so I would think all 3 4S strings would be of similar capacity.

author: james_s
author_rank: Super Contributor
timestamp: March 18, 2022, 01:42:52 am
content: As long as they're all the same chemistry and configuration it makes no difference.

author: amyk
author_rank: Super Contributor
timestamp: March 18, 2022, 02:37:33 am
content: If you conceptually cut a battery in half, you get two cells of half the capacity of the original, and if you put them in parallel, they become one. If you cut a battery into thirds and put two of them in parallel, then the third, why would it matter? Each piece will discharge at the same voltage, and if they're all the same chemistry, then they'll be at the same (percentage) state of charge.Having the same capacity is only important for cells in series, as otherwise one would become completely depleted long before another and be damaged by reverse-charging.
Mixing digital signals of same frequency to a frequency the sum of the input - Page 1
Forum section: electronics / beginners

author: AFBlumen
author_rank: Newbie
timestamp: July 22, 2019, 05:13:20 am
content: Hello Guys. Good dayI wanted to mix 4 1GHz digital signals to a single 4GHz signal.Let's name them A, B, C, Dso every a nanosecond they pulse one time. And I plan to multiply the four input signals by 4.So they will pulse 4 times per nanosecond and using a clock to time them.So if the input in input A is A1, A2 the output is A1, A1, A1, A1, A2, A2, A2, A2.Then,A1, A1, A1, A1B1, B1, B1, B1C1, C1, C1, C1D1, D1, D1, D1with the clock will be A1, B1, C1, D1 in 4 times the input frequency.Am I right there?Thank you!

author: MagicSmoker
author_rank: Super Contributor
timestamp: July 22, 2019, 02:18:24 pm
content: If the 1GHz pulses have a 50% duty cycle and are phase-aligned then, no, you can't combine them. If you can reduce the duty cycle to much less than 25% (e.g. - 10%) and phase-shift them by 90 deg. from each other (e.g. - 0, 90, 180, 270) THEN you could combine them with OR gates (perhaps even with Schottky diodes, though I'm more of a power electronics guy than digital, much less 1GHz+ stuff).Draw this out on a piece of paper and you'll likely see why.

author: David Hess
author_rank: Super Contributor
timestamp: July 22, 2019, 03:34:26 pm
content: Some low noise frequency doublers work exactly like that. A quadrature signals ( 0 and 90 degrees or -45 and +45) is produced from a single input and fed to a mixer which adds them together to double the original input.If the single frequency inputs to the mixer are not held in quadrature, then a DC offset at the output is produced. So assuming the 4 inputs are phase coherent, filter the DC output from the mixer, compare it to zero, and use that to drive a voltage variable phase shifter at one input.If the sources are *not* phase coherent, like from separate oscillators, then do the same thing but control the phase and frequency of one oscillator.
Mixing Flux Types - Page 1
Forum section: electronics / beginners

author: superscott319
author_rank: Contributor
timestamp: August 16, 2013, 07:24:56 pm
content: If I was working with a cored solder that used a no-clean formula or water soluble based flux, would there be any issue with later adding rosin based flux from another solder or flux pen to that?Thanks for taking the time to answer my question.

author: nanofrog
author_rank: Super Contributor
timestamp: August 17, 2013, 12:28:18 am
content: You could get some odd properties by doing so, as well as one heck of a mess. So I'd skip doing so unless the data sheet specifically mentions it can be mixed, and with what (IIRC, some rosin & no-clean formulations can be).Water soluble formulations OTOH, are corrosive and must be cleaned off (also conductive). So I wouldn't expect this to be able to be mixed with either rosin or no-clean at all.

author: superscott319
author_rank: Contributor
timestamp: August 19, 2013, 03:36:19 am
content: One issue I'm commonly experiencing when desoldering, (especially lead-free joints) is being able to get the joints hot enough for my solder sucker to remove the existing solder. Some of the advice I've been getting here for fixing that problem is to add extra solder to the existing joint to help it melt.By adding new solder to existing solder, I could be mixing two different types of fluxes and without knowing what type of flux the manufacture used, it would be impossible for me to add solder with compatible flux.For simply adding solder for the purpose of desoldering, does the potential of mixing fluxes matter?

author: robrenz
author_rank: Super Contributor
timestamp: August 19, 2013, 04:16:42 am
content: Just clean the joint before you add your solder. Flux is not captive in the solder metal of a joint like an alloy, it is only on the surface if not cleaned off. Fluxed solder is a tube with flux filling the center hole. (multicore just has multiple holes filled with flux)

author: pickle9000
author_rank: Super Contributor
timestamp: August 19, 2013, 04:49:48 am
content: Remember when using a solder sucker suck from the side with the most mass if possible. A large amount of foil will act as a heatsink and prevent the solder melting. That also means using a big tip as opposed to a high temp. A monster sized solder sucker helps as well. Soldapullit pump style the big blue one with the yellow tips is great.