hybridfree/eevblog-posts huggingface dataset:
Help me translate SMD marking code => component value/id - Page 1
Forum section: electronics / beginners

author: Gaktyt
author_rank: Regular Contributor
timestamp: January 08, 2020, 03:01:25 pm
content: Hi folks,In order to attempt repairing the front-end of my scopehttps://www.eevblog.com/forum/repair/siglent-oscilloscope-sds2104x-repair-help/I need to know the component value (part id/number) so that I can order it.K52G- SOT-23 I believe it's a transistor of some sort NPN/FETAUE 6683- SOIC-8 I believe it's a op-ampT4- I believe it's a diodeCan you please assist?I have attached a picture of the front-end

author: Yansi
author_rank: Super Contributor
timestamp: January 08, 2020, 03:15:23 pm
content: you would do better just supplying a detailed photo, than the rewritten marking, as the the "K52G" is likely just "K52" (BAV199 diode) ang G is some other indentifier.The board look awful lot like an oscilloscope input buffer, so a BAV199 seems legit in that obligatory circuit, also in the place near "3EM" (MMBTH10).Not sure what 6683 may be from a brief search. Send please just a detailed photo. Experienced eye may guess even the manufacturer of the IC, based on the package and marking font style.

author: mikerj
author_rank: Super Contributor
timestamp: January 08, 2020, 03:39:32 pm
content: AUE is probably anOPA72720MHz precision op-amp.

author: Gaktyt
author_rank: Regular Contributor
timestamp: January 08, 2020, 04:08:34 pm
content: Hi YansiQuote from: Yansi on January 08, 2020, 03:15:23 pmI hear you, but that is the best I can do with my equipment, but Dave made a teardown of the scope in much better quality and even promised some hi-res pictures (which I can't find). look herehttps://www.youtube.com/watch?time_continue=1018&v=E3B4OTV8f1o&feature=emb_logofront-end is at 16:58Quote from: Yansi on January 08, 2020, 03:15:23 pmThank you for the K52 and 3EM, I have the feeling that the real culprit is the 6683.

author: Gaktyt
author_rank: Regular Contributor
timestamp: January 08, 2020, 04:12:10 pm
content: Hi mikerQuote from: mikerj on January 08, 2020, 03:39:32 pmThank you for your suggestion, based on the pin-out it is likely, but a 20MHz op-amp in a 300MHz scope front-end, does that seem probable?

author: Yansi
author_rank: Super Contributor
timestamp: January 08, 2020, 05:10:40 pm
content: Why wouldn't it?There are a lot of jobs for precision low speed opamps in DSO input circuitry, such as the input DC servo or input offset control.Most of the cheap scopes do in fact have a fully discrete frontends, as they are cheaper, than unobtanium high speed opamps.

author: Gaktyt
author_rank: Regular Contributor
timestamp: January 08, 2020, 06:11:58 pm
content: Quote from: Yansi on January 08, 2020, 05:10:40 pmI'm just raising the question for the reason stated earlier, I'm not claiming it's totally out of place, because as you say; there are lot of jobs for a low speed op-amp in the front end.
Help me try my new Rigol Oscope - Page 1
Forum section: electronics / beginners

author: TubeRadio
author_rank: Newbie
timestamp: November 13, 2014, 07:16:40 am
content: Hi All, I have purchased a Rigol DS1054Z (and saved with the EEVBlog discount).I'm new to these devices. I have an old VIZ signal generator would like to examine the wave on my scope. Could someone step me through that? I assume to set the sig-gen to 0-50mhz, connect its output + and - to the probe.But I have no idea what to set the unit on to see the sinewave.I can also modulate the sinewave with a tone, and would like to turn that modulation on and see that as well.Any replies greatly appreciated!

author: SebG
author_rank: Regular Contributor
timestamp: November 13, 2014, 07:38:38 am
content: HeyIf you use your Rigol probe then connect it to the + of the signal generator and the alligator clip on the probe to the - or ground of the sig-genTo set up the verticle and horizontal scale on the scope you can just adjust the large two knobs until you see your signal or you can click the AUTO button on the top next to the Run/Stop button that. That will automatically do it's best to display the waveform and then you can adjust it if you need using the larger knobs.

author: jancumps
author_rank: Unknown
timestamp: November 13, 2014, 07:46:41 am
content: If your signal generator output is intended for 50?, you'll have to take care that the load at scope connector is 50?.
Help me understand memory IC's memory organization. - Page 1
Forum section: electronics / beginners

author: MarkS
author_rank: Unknown
timestamp: February 27, 2025, 07:00:11 pm
content: I'm coming from the software side, where a megabyte of available RAM is a megabyte of available RAM. When I look at memory IC's, however, it gets all weird. For instance, a 64Kx8 SRAM has 65536 8-bit bytes, but a 64Kx16 has 131,072 8-bit bytes or 65536 16-bit words? Or to put it another way, a 64Kx8 has 64K of memory, but a 64Kx16 has 128K? Is this correct?

author: pqass
author_rank: Super Contributor
timestamp: February 27, 2025, 07:58:00 pm
content: Quote from: MarkS on February 27, 2025, 07:00:11 pmYes.And when you look at the datasheet for a particular SRAM chip you'll see size in {kilo|mega}bitsand then its organization (eg.128K x 8or64 x 16).

author: MarkS
author_rank: Unknown
timestamp: February 27, 2025, 10:00:00 pm
content: Quote from: pqass on February 27, 2025, 07:58:00 pmThank you. The thought that if I want 32K of RAM in a retro computer with a 16-bit data bus, as an example, I would need one 16Kx16 or two 16Kx8 chips just kind of breaks my brain a bit. I get it now, but my eye still twitches at the though that one "16K" chip = 32K!

author: CaptDon
author_rank: Super Contributor
timestamp: February 27, 2025, 11:05:05 pm
content: For the longest time since the evolution of 8 bit computers we still think in terms of 8 bit bytes. Also, for the longest time I.C. packages couldn't support more than 8 bits due to pin count. Memory had 24, 28, 32 and later more pins. Remember, you need 8 for data, probably 4 or 5 more for control and many more for the address lines. Now we commonly find BGA packages with 144 pins or more. 8 bit memory chips are still probably at least 50% of the marketplace so for 16 bit wide memory you generally need at least 2 memory packages.

author: tooki
author_rank: Super Contributor
timestamp: February 27, 2025, 11:55:09 pm
content: Quote from: MarkS on February 27, 2025, 10:00:00 pmThe “16K” causing you fits should not be looked at as “kilobytes”, but as “number of rows” or similar. It is part of the larger term (e.g. 16Kx16) that describes the structure, not (just) the size.
help me understand noise sources (series vs shunt), analog switch - Page 1
Forum section: electronics / beginners

author: SArepairman
author_rank: Frequent Contributor
timestamp: June 07, 2014, 08:55:23 am
content: I don't know how to approach a analog switch. Say there is an op-amp voltage follower with a analog switch on it that shorts the input to another follower (shunt resistance)How does the noise on the op amp sees on the input change when the switch is open and closed? How about the op-amp with the switch (that is in series with the input now, so its like a series resistance)The analog switch has a xnV/hz noise. (probobly like 3nV/hz realistically)Can someone explain what happens to the op-amps in each situation (series switch vs shunt switch open vs closed). I think that explaining this stupid puzzle will greatly benefit me.the signal being fed into the beginning of this circuit is also a voltage follower.like thiswhere the two top op amps are connected to eachother with a wire, the analog switch (cmos) only connects an additional OPA as a "load"
Help me understand Tcase / Tjunction - Page 1
Forum section: electronics / beginners

author: cichy45
author_rank: Contributor
timestamp: March 12, 2022, 05:07:44 pm
content: Hi everyone!So, I struggle to understand, what precisely Tcasemeans?Working on DC Load, I decided to test some mosfets for linear operation. My setup is: DIY xhdz-fz-2g board for electronic load control that I use to control various mosfets, Intel BOX cooler with copper core as heat sink.Mosfet is soldered to copper core using low melting temperature solder Sn43Bi57 (138 degree C melting point). Heat sink is drilled through copper core and thermocouple is placed directly at TO220 tab.Is this correct way of measuring mosfet temperature at its case? I tested AOT12N50 this way and my results are on plot below:Tjunctionwas calculated using formula: Tcase+ (0,5 C/W * Pdissipation).Is this the correct approach? I know that almost all datasheet data is "theoretical" like max power dissipation with tcase at 25 degrees that is impossible in real life, so I wanted to build myself some real world data.

author: golden_labels
author_rank: Super Contributor
timestamp: March 12, 2022, 09:06:26 pm
content: Before continuing: the pad, to which you connected the thermocouple, is nearly surely electrically connected to one of the pins. Which means your thermocouple, unless electrically isolated, is also receiving voltage from that pin.Tcasemeans precisely… nothing specific. Some manufacturers, like Intel, publish the testing methods,(1)but most do not. You may safely assume that Tcaseis the temperature at the place that is used to exchange heat with surroundings. If a heatsink is expected, it will be where you put the heatsink. With TO-220 package that will be the metal pad on the back.(1)Which is not as helpful as one may think, as their definition requires physically altering the device.

author: strawberry
author_rank: Super Contributor
timestamp: March 12, 2022, 09:21:49 pm
content: Tjunction is transistor or ~100um surface layer of siliconTcase is surface temperature of case regardless heatsink or not

author: cichy45
author_rank: Contributor
timestamp: March 12, 2022, 09:32:36 pm
content: Quote from: golden_labels on March 12, 2022, 09:06:26 pmI am aware of that. In fact, my whole heat sink is live, as transistor tab (drain) is soldered directly to it. But thanks to it, thermal resistance is minimal, as solder is conducting heat quite well.I was just wondering, if case means metal back/tab of transistor package, or the epoxy case with part number/date code etc.

author: strawberry
author_rank: Super Contributor
timestamp: March 12, 2022, 09:41:59 pm
content: usually mounting surfacesometimes both top and bottom resistancessilicon max operational temperatureepoxy max temperature
Help me understand these two inverters and the buffer in this schematic - Page 1
Forum section: electronics / beginners

author: JoeN
author_rank: Frequent Contributor
timestamp: March 29, 2016, 04:25:21 am
content: 74LS164:Is there a reason for one inverter having a "pre" bubble and the other having a "post" bubble? What is this supposed to signify? I have no idea.For the inverted inverter, I assume this means a buffer and the signal is coming out as it is going in. What is the purpose? To provide more drive because it is going to 8 inputs? Or possibly to provide a delay? And why not just use a buffer symbol instead of an inverted inverter?Thanks!

author: IconicPCB
author_rank: Super Contributor
timestamp: March 29, 2016, 04:39:20 am
content: the "bubble You refer to is logic level inversion.The post "bubble" states whtever happened before it reached me is now logically inverted outputThe pre "bubble" states whatever normally happens when I am not here is now active Low logic

author: ataradov
author_rank: Super Contributor
timestamp: March 29, 2016, 04:55:01 am
content: And inversion on both sides is done to increase drive strength. Typical TTL fanout should not exceed 10 gates, so signal coming from the outside has to be buffered for distribution to so many gates.
Help me understand this DSO measurement (stupid newb, or really bad wall wart?) - Page 1
Forum section: electronics / beginners

author: nikodemus
author_rank: Newbie
timestamp: July 23, 2013, 01:34:43 pm
content: I was comparing a couple of wall warts with an oscilloscope, and by accident discovered this:CH1 is the positive contact on the wall-wart output, with probe ground lead unattached. (So from positive contact to DSO ground, I think?)CH2 is the same reading from the negative contact.MATH is CH1-CH2. Wall-wart is rated 15V, so that matches... but that apparent 220AC between wall-wart and ground worries me quite a bit!I made a comparison to a second wall wart of different make (this one rated 9V), plugged into the same output, same setup with ground leads hanging, etc:No sign of apparent mains AC in relation to scope ground.Is this normal and harmless for some type of power supplies, or should I be about as alarmed as I am? Or what?

author: madires
author_rank: Super Contributor
timestamp: July 23, 2013, 01:47:46 pm
content: Capacitor for EMI suppression between primary and secondary?

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 23, 2013, 02:17:30 pm
content: Since the wall wart is isolated from the mains, why would you not just use ch1 on the scope to measure the output?

author: David_AVD
author_rank: Super Contributor
timestamp: July 23, 2013, 10:21:00 pm
content: The high voltage is from either a suppression capacitor or leakage across the power supply transformer. It's a very high impedance source.

author: Odysseus
author_rank: Regular Contributor
timestamp: July 24, 2013, 03:32:04 am
content: Not a huge deal. If you really want to quantify what you're dealing with, you can measure the capacitive AC current from the output to earth ground with a meter. It will likely be in the uA range.

author: nikodemus
author_rank: Newbie
timestamp: July 24, 2013, 11:14:56 am
content: Many thanks for the explanations! I'll measure the capacitative current as you suggest.Re. why did I measure it that way? I was about to measure the wart with just CH1, when I touched the probe to one of the contacts before the ground lead was attached... The scope happened to be on fairly large vertical scale and WHAM the AC waveform jumped on the screen. Nearly pissed myself....at which point I didn't quite dare attach the ground lead anymore.A couple of followup questions:- Is this typical/inevitable for power supplies with similar design?- Are there situations in which such a capacitative current is highly undesirable vs. situations where is doesn't really matter at all?
Help me understand this UART circuit - Page 1
Forum section: electronics / beginners

author: Muku
author_rank: Contributor
timestamp: September 03, 2020, 09:28:59 pm
content: Hello, everyone!I found this circuit in the datasheet of a GSM module, SIM800C. I guess this is some kind of level conversion because the data sheet says not to exceed 2.8V on the UART lines. Now I understand using a resistor divider to drop the voltage but I don't understand how the above circuit. Could anyone help me understand this, I might learn something new? How is the UART1_RXD pin going to see the TXD voltage because of the diode? VDD_EXT is an output voltage from module of 2.8v which is guess there for using with level changing circuit.

author: ledtester
author_rank: Super Contributor
timestamp: September 03, 2020, 09:48:04 pm
content: Presumably it seems that the "DTE" device operates at 2.8V and the "Module" side operates at 3 or 3.3V.If the DTE makes TXD high (i.e. 2.8V) then UART1_RXD will also be high being pulled up by the 10K resistor.Code:3.3V 3.1V 2.8VVDD_EXT --- /\/\/ ---- --|>|- --- TXD10KI say "3.1V" here because some current has to flow through the resistor to create the voltage drop across the diode.If the DTE pulls TXD low then the other side of the diode will be like 0.6V which hopefully still registers as a low for the module.Code:3.3V 0.6V 0VVDD_EXT --- /\/\/ ---- --|>|- --- TXD10KBasically the diode raises the high voltage level of the DTE by something like a diode drop.The other diode lowers the high voltage level of the Module by 0.6V.
Help me with designing a toslink output circuit - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: September 11, 2018, 08:10:09 am
content: Hi everybody,i have a yamaha keyboard here with a dead left+right output but the headphone out works.first i need to see if the DAC or if the output jacks is damaged.Anyway i wanted to add a toslink output if i am in there working on the DAC.should i break off the signal from the L+R input pins on the DAC to avoid conversion to analog. or should i pull it off the dac outputs?Then i was thinking about using one of these cheap USB SPDIF DAC, but would it work if i pulled off the usb from the board and wire the dac inputs to it...https://www.ebay.com/itm/DAC-Decoder-PCM2704-USB-Audio-Sound-Card-Module-Analog-SPDIF-Coaxial-HiFi-Decord/182843205108?hash=item2a924de5f4:g:IygAAOSwigRa2wG7

author: dmills
author_rank: Super Contributor
timestamp: September 11, 2018, 09:19:42 am
content: Odds are good that the problem is the socket (Connectors are almost always the way to bet with MI gear).I would be very surprised to find the DAC on that keyboard had separate L, R INPUTS, they almost all use some variant of I2S or its similar kin.Assuming one of the usual sort of SPDIF interface chips (a CS-something or other?) you will need Data, LRCLK, SCLK and (probably) a MCLK at 128 or 256 times the audio sample rate, these are most likely available on the DAC chip.Regards, Dan.
Help me with some triac optoisolator questions (Vishay VO3023) - Page 1
Forum section: electronics / beginners

author: dsegel
author_rank: Contributor
timestamp: February 07, 2018, 02:57:08 pm
content: I have some of these (VO3023) and am wondering if and how I can use them in a specific project where I will be driving them with an Arduino Pro Mini using digitalWrite. I've never used optoisolators before.Here's the datasheet:http://www.vishay.com/docs/84132/vo3020.pdfHere are my questions:1. Do I have to use a resistor on the input to the chip to protect the internal LED? It looks like the trigger current is listed as 5mA, so that would mean a 1K resistor for a 5V signal, right?2. Most circuits I see using this kind of optoisolator drive an external triac. Why would I need that since this has one internally?3. If I do use an external triac, what purpose do the resistors (56R and 100R) in a circuit like this perform:https://www.electronics-tutorials.ws/articles/opto6.gif4. How much current can I pass through the internal triac? Is that the "RMS On State Current"?5. Finally, probably the biggest question - I need to use it to turn a DC line on and off that may have it's polarity reversed (i.e. positive and negative are reversed sometimes). Is this OK with a triac, and how do I calculate the current when specs are written for RMS?Thanks in advance to everybody.

author: Benta
author_rank: Super Contributor
timestamp: February 07, 2018, 03:19:15 pm
content: 1: yes.2: to increase power capability.3: limit the gate current.4: yes.5: a triac optocoupler is not suited for DC. Once it's turned on it will not turn off until power is removed (or AC reverses polarity).

author: dsegel
author_rank: Contributor
timestamp: February 07, 2018, 06:57:16 pm
content: I have a relay to cut power to the triacs after they do their thing (briefly energizing the coil of an electromagnet). The only reason I want to use a triac is because I need to switch on and off current flowing in either direction (the direction of the current flow is reversed to switch the pole of the electromagnet), and I will eventually have 56 of them so individual relays would make me unhappy.

author: Benta
author_rank: Super Contributor
timestamp: February 07, 2018, 07:20:59 pm
content: QuoteWon't work. When the triac is on, it's on. Cut current to the LED and it still stays on.Avoiding the polarity reversal is probably a better idea, either with a bridge rectifier or just a series diode before your circuit.

author: dsegel
author_rank: Contributor
timestamp: February 07, 2018, 08:48:31 pm
content: I meant that the power the triac is switching will be cut by the relay, not the gate signal.And I need to reverse polarity to swap the ends of the magnets (north-south).
help needed - Page 1
Forum section: electronics / beginners

author: ropes712
author_rank: Newbie
timestamp: February 01, 2021, 09:26:38 pm
content: HelloI am a electronics novice, and I am looking to create a Rocket ignition system using nichrome wire. The circuit is attached. The battery symbolised by a 2.7v cell connects to a capacitor' This capacitor discharges into the nichrome wire, causing the fuel in the rocket to burn. My main convern is the safety LED and Buzzer. is it possible to connect more than one circuit to the same battery; would this just have the effect of increasing the amperage draw?Would this system work? And if not, what changes can I make and why?

author: IanB
author_rank: Super Contributor
timestamp: February 01, 2021, 09:34:18 pm
content: Quote from: ropes712 on February 01, 2021, 09:26:38 pmYou want to create a safety critical system that could cause harm to you or others if it malfunctioned, and you don't know what you are doing?I'm not sure it is a good idea to help you. Sorry. Please buy one from a reputable source that can be trusted.

author: Zero999
author_rank: Super Contributor
timestamp: February 02, 2021, 09:43:44 am
content: The circuit is very difficult to follow. Try redrawing it with as fewer wires crossing as possible, the positive power at the top and multiple ground symbols, rather than connecting everything to one.Why are you concerned about the LED and buzzer?I echo the concerns above regarding safety critical systems and inexperiance. You really need to higher a professional, if you don't know what you're doing.
Help needed for Capacitors - Page 1
Forum section: electronics / beginners

author: kingoftaurus
author_rank: Contributor
timestamp: March 27, 2014, 06:50:43 am
content: So, I have a dilemma.Minor, but still there.I have a set of ceramic capacitors with ONLY their capacitance value marked.IE 104 103 102 101Ive noticed, that, say I have a 104. Its capacitance is 100nF and its VOLTAGE is 50v.I see that the 101 the 100pF cap its VOLTAGE is 100vThese capacitors are exactly the same size (compared to others on digikey)my problem is that these are the only ceramics that I have.I need to come up with:.05uF and 500Vim assuming that 2 104 in series will give .05uF but the voltage would be 200v right?

author: Richard Head
author_rank: Frequent Contributor
timestamp: March 27, 2014, 06:54:09 am
content: The voltage rating will double when connecting equal values in series.

author: kingoftaurus
author_rank: Contributor
timestamp: March 27, 2014, 07:00:31 am
content: Quote from: Richard Head on March 27, 2014, 06:54:09 amSo for temporary usage, I would need 5 100v caps in series ?? lol ok..

author: Richard Head
author_rank: Frequent Contributor
timestamp: March 27, 2014, 09:07:44 am
content: Yes

author: KJDS
author_rank: Super Contributor
timestamp: March 27, 2014, 10:18:45 am
content: NOThe voltage across the caps will not be shared equally. Imagine one has a leakage resistance of 1Gohm and another has a leakage resistance of 10Gohm.That would leave 90% of the voltage across the one with the higher resistance. The usual solution to this is either to buy the right capacitor and when that is not possible put a resistor in parallel with each capacitor. Just make sure that the resistor can cope with the power and that you still have some margin on voltage too.

author: Richard Head
author_rank: Frequent Contributor
timestamp: March 27, 2014, 11:39:58 am
content: Assuming the leakage currents are equal that is. If the leakage currents differ by an order of magnitude then all bets are off, but with film caps of the same type the leakage currents are very likely going to be similar. But technically KJDS is correct.

author: KJDS
author_rank: Super Contributor
timestamp: March 27, 2014, 01:26:46 pm
content: Quote from: Richard Head on March 27, 2014, 11:39:58 amI'm practically correct too, it only takes a fingerprint to make that sort of difference.

author: kingoftaurus
author_rank: Contributor
timestamp: March 29, 2014, 02:00:52 am
content: Alright, So I'll just wait. I cant imagine why I need one rated for 500V. Stupid old thing. lol. At least there isn't very many caps in it. (old old oscilloscope from a different thread)
Help needed identifying component! - Page 1
Forum section: electronics / beginners

author: gubenena
author_rank: Newbie
timestamp: November 07, 2017, 06:28:31 pm
content: Thank you in advance for the help !Need to identify the burned component.It's a water faucet, with lmv358 and PIC16F526-I/ST, and some infrared receiver/transmitter, etc...In the faucet it self there is a solenoid valve 14w of power.Faucet runs on a crp2 battery 6v, 1.4A.

author: grifftech
author_rank: Frequent Contributor
timestamp: November 07, 2017, 08:33:51 pm
content: DABZ8

author: Gyro
author_rank: Super Contributor
timestamp: November 07, 2017, 08:37:04 pm
content: QuoteYes obviously, but what manufacturer / part number is that?Edit: I've been trying to help but haven't found a match yet.

author: gubenena
author_rank: Newbie
timestamp: November 07, 2017, 09:36:21 pm
content: Quote from: blueskull on November 07, 2017, 08:42:54 pmThank you blue and others!.Can I please ask you blueskull for a brief explanation on how did you came up with the part number.My wild guess would be that you are familiar with the design, or simple there are people in this business that pretty much can figure out almost any design as soon as they see it !.If am not asking to much, which I know I do, if you are able to as sad before just shortly elaborate or I will not push my luck with the elaboration, maybe just a simple hints, so I do the rest of the work myself !...Thank you either way !

author: Nusa
author_rank: Super Contributor
timestamp: November 07, 2017, 10:33:42 pm
content: He meant date code.Not the only one, but this one is better than most on smd part codes:http://www.s-manuals.com/smdStart with the first two letters. Then if you find some matches, look at the package type.

author: gubenena
author_rank: Newbie
timestamp: November 08, 2017, 10:35:35 am
content: Thank you guys !

author: gubenena
author_rank: Newbie
timestamp: December 05, 2017, 02:59:20 pm
content: By measuring components seems like it's not the one !

author: gubenena
author_rank: Newbie
timestamp: December 05, 2017, 03:11:29 pm
content: Looks to me more like TPS61040...Which rather fits with pin outs ! Though again am not really sure....Thanks !
Help needed identifying re-usable material from PLC and HV boards - Page 1
Forum section: electronics / beginners

author: jorgeh
author_rank: Regular Contributor
timestamp: July 18, 2022, 10:51:23 pm
content: HiIm trying to learn better identify re-usable material / donor boards from "low" quality e-waste.The pictures Im uploading are example of material that get sent to the recycling center, and afaik this material usually gets shredded. preventing to be re-used.e-waste doesent mean 100% defective material. some of them gets generated from upgraded systems, new constructions, storage clearance or bankrupcy.It would be great if some of this material gets re-used. either as donor board or for educational purposes.

author: jorgeh
author_rank: Regular Contributor
timestamp: July 18, 2022, 10:52:23 pm
content: more boards

author: free_electron
author_rank: Super Contributor
timestamp: July 18, 2022, 11:26:27 pm
content: very littlethe transformers could be usefulrelays ? probably burnt-in contacts. who knows how many cycles they have on them...capacitors ? probably cooked by now...processors and ram ? useless. the world has moved on. by the time you get those running and find compilers for them... not worth the effort.connectors. i see doubles sided/multilayer boards . that's going to take some effort to take off... and or equipment. ( desoldering station , solder litz wire.. cost more than the connectors themselves)the fuses in sockets are useful. you can always use a working fuse...if those phoenix contact terminal blocks plug in : those are useful. the board side : too much hassle to remove.

author: inse
author_rank: Super Contributor
timestamp: July 19, 2022, 04:56:42 am
content: I would keep a selection of the boards and desolder parts when I need them.One day you might need an inrush limiter or X- capacitor or that specific logic IC for repair.Disassemble the sandwiches and keep the mounting material, screws and mounting bolts.
Help needed: Industry Research - Mentor Graphics vs SEE Electrical vs others - Page 1
Forum section: electronics / beginners

author: tmk21
author_rank: Newbie
timestamp: July 11, 2016, 04:49:00 pm
content: I am an electrical engineer by training, but I am actually conducting some industry research to try and learn about the eCAD industry. I have loads of questions, but at the highest level:- How do the platforms from Mentor Graphics and IGE+XAO (SEE Electrical) compare? (pros/cons...)- Is another platform much better? If so, which one!? (I realise that this will depend on requirements, usage etc.)- Which platform is more commonly used? Does it vary by industry (or geography etc.)- Which are the most commonly used platforms for harness design?It would be great to speak with people who have experience of either of these two platforms (either positive or negative!)Thanks,
Help needed, my switching voltage regulator is not working - Page 1
Forum section: electronics / beginners

author: famez
author_rank: Newbie
timestamp: February 26, 2025, 11:23:13 pm
content: Hello everyone,First of all, I want to let you know that I am a total noob, I am telecommunications engineer working for a company that manufactures embedded devices. My background is more related about embedded software / cybersecurity.So, I wanted to desing my first board, and I tried with RPI PICO (RP2040) following the electric schematics publictly available here:https://datasheets.raspberrypi.com/pico/pico-datasheet.pdf(page 25).I designed everything and sent it to JLCPCB for manufactoring.When connecting the PCBA to the USB, it was not recognised by my computer.I started measuring 3V3 signal with a multimeter and it gave me only 0.5V and I don’t know why. I suppose that the problem is the voltage regulator (because the USB is giving me 5V).So, I just desoldered the voltage regulator and injected and external 3V3 voltage supply. With this, my PCBA is working as expected (I flashed a simple SW to make a led flash, and it is working).Can you help me, please? I know that some traces have incorrect angles (more than 90 º). Could it be the problem? Any other good design rules or tips are appreciated.By the way, no errors in the DRC, only warning about silkscreen, but I didn’t send the silkscreen layer to be manufactured.Thanks in advance!!PD: The project is attached in this thread in zip format. It is a Kicad project.PD2: The voltage regulator is this model: RT6150BGQW (from 5V to 3V3).Let me know if you need further details.

author: xvr
author_rank: Frequent Contributor
timestamp: February 27, 2025, 10:56:51 am
content: FB pin should be connected to voltage divider, not directly to output. In this configuration you will get 0.5V on output (not 3.3V)Also copper area under U2 is too small. It used as heatsink. In your configuration U2 can get very hot (or even shut down on overheat)

author: xvr
author_rank: Frequent Contributor
timestamp: February 27, 2025, 11:01:07 am
content: Quote3.3V model is RT6159B33GQW

author: famez
author_rank: Newbie
timestamp: February 28, 2025, 11:59:05 pm
content: Thanks for your reply. That was exactly my problem, I tested it manually and seems to work.
help needed nidec 24v motor - Page 1
Forum section: electronics / beginners

author: delbertdunce
author_rank: Newbie
timestamp: February 15, 2019, 04:28:33 pm
content: Hi all,new to this forum. If I'm not in the right place please let me know.I have a Nidec 24v motor which I believe came out of an old fax machine. It has 6 wires going into the circuit board, can anybody tell me how I can connect it to a 24v supply.Thanks DD

author: Doctorandus_P
author_rank: Super Contributor
timestamp: February 15, 2019, 10:21:26 pm
content: You can start by reading.If you read the label you can see "DC24V".Then look at the PCB.The connector has nice labels on them.Do you understand the text next to those labels?There is also a piece of aluminimum screwed onto the PCB.Under that Aluminimum is a chip.That chip is the motor controller.It's very likely you feed it 24V dc and some logic signals.Look up the datasheet of that chip and you will probably have more information about controlling your motor than you need or even want to know.
Help needed replacing a switch on a table saw - Page 1
Forum section: electronics / beginners

author: WolfgangIII
author_rank: Newbie
timestamp: April 17, 2024, 11:40:40 am
content: Hello everyone, I am seeking some advice, and as I don't know anyone whom I can ask directly I have turned to the good people of the inter net for help.it's a straight forward problem, the switch on my table saw stopped working, only worked when manually held in. So I bought a replacement on line and assumed as it is almost identical that the wiring would also be. When I connected it up, it just kept tripping the power. Then I thought it may be the capicator, so I replaced that. Same issue. Finally I had a look on the side of the switch and I see the wiring is different. I was hoping someone could tell me the corrisponding numbers from the two circuit diagrams.

author: WolfgangIII
author_rank: Newbie
timestamp: April 17, 2024, 12:31:29 pm
content: Thank you very much. I have to go buy some ceramic fuses before I can try it out, but I will let you know what happens.

author: WolfgangIII
author_rank: Newbie
timestamp: April 18, 2024, 10:34:22 am
content: I got it working. Thanks to your help wraper. It took some figuring out, but nievely from my part I discovered the pin position on the switch didn't match the pin position in the diagram on the side of the switch . On the new switch I could see the pins marked with numbers but it wasn't till l put on stronger glasses I saw the very feint numbers on the original switch. Live and learn.
Help needed to understand one schema - Page 1
Forum section: electronics / beginners

author: Mm
author_rank: Contributor
timestamp: October 25, 2023, 05:51:02 pm
content: I'm creating square wave generator based on this schema.https://image.easyeda.com/histories/e3a1f3078b784218a866198863a4681f.pngIdea is to have input source and use mosfet with gate driver to create square wave signal to output. Signal generator is used to adjust the gate driver frequency.I have needed components, but I have questions about the schema.1) First of all, lets start with the output. If I set my output device on place where COIL L1 is located am I doing things correct? Or can I use U2 or C1 as output?2) what is the purpose of D1, D2, U1 and C1 and in this schema? Are they needed to make this square pulse to work or are they something extra Ivo needed for something else?D1 is something I do not understand at all in stis schema, is it needed?D2 is kinda allowing to bypass the mosfet switch completely and do not make any sense to me.U1 seems to me something not needed for this square wave generator to work.C1, what is the purpose of it?3) there is 12V battery and VCC. Why? Is it ok to have just 12V battery with buck converter to have higher voltage?4) what is the purpose of R2 and C1?Thx for help

author: m k
author_rank: Super Contributor
timestamp: October 30, 2023, 08:02:20 pm
content: GND should go to L1 pin 2.

author: Bud
author_rank: Super Contributor
timestamp: October 30, 2023, 09:02:06 pm
content: This circuit makes no sense. First, it is not a 'generator'. Second, when you will try to drive the output transistor it will short the battery to ground. Best case the battery will be damaged and/or transistor will blow up, worst case you will have a fire.I can see you do not know what you are doing. You need to educate yourself on power converters.
Help needed with clamping diodes.  - Page 1
Forum section: electronics / beginners

author: peps1
author_rank: Regular Contributor
timestamp: February 07, 2022, 07:33:54 pm
content: Hi, just wondering if I can get a little help understanding what going on here with this diodeI believe its a clamping diode, but not 100% or if that's all it's doing.Here is what I think is going on but would love some clarification or correction. The diode is charging/discharging the cap so if the signal drops below the diode threshold it will drop the bias down and reducing the signal and cutting the noise floor form the gain stage?

author: Kim Christensen
author_rank: Super Contributor
timestamp: February 07, 2022, 09:20:37 pm
content: It took me a second to realize that this circuit is positive ground with PNP transistors.D1 is there to provide a path for current to flow so that the Emitter-Base junction of Q3 doesn't get reversed biased by more than apx 0.3Vie:when the AC cycle goes "negative" at Q2's collector, current through C2 flows via Q3's base and during the opposite direction it flows via D1.

author: peps1
author_rank: Regular Contributor
timestamp: February 07, 2022, 09:39:28 pm
content: Thank you Kim, So is it mainly there to keep a tighter bias on Q3, during Q2 negative swing?Would this have any compensation effect on say the bias drifting if the Q3 Ge transistor warmed up, as these old pedal designs have a habit of playing up in warm conditions?

author: Kim Christensen
author_rank: Super Contributor
timestamp: February 07, 2022, 10:31:54 pm
content: Well, essentially there is no DC bias on Q3 at all. When there is no audio signal, Q3 is turned off and only leakage current flows through Q3 & R7. It is a class-B amplifier and only amplifies 1/2 the waveform (As opposed to a class-B push-pull with 2 transistors). The "Fuzz" control determines how hard it is driven. Lots of distortion which I think is the point of this guitar fuzz circuit.I probably didn't really explain it that well. D1 gives a path for C2 to "discharge" through after it has been "charged" via the base-emitter junction of Q3. Otherwise C2 would just charge up to a certain voltage and little to no current would flow into the base of Q3. Think of Q3's base-emitter junction as another diode in parallel with D1 but connected with the opposite polarity.

author: peps1
author_rank: Regular Contributor
timestamp: February 07, 2022, 10:54:40 pm
content: Quote from: Kim Christensen on February 07, 2022, 10:31:54 pmAhhh like clipping diodes using D1 and Q3! that makes sense. Thank you.
Help needed with my project. - Page 1
Forum section: electronics / beginners

author: Estonian
author_rank: Newbie
timestamp: March 27, 2024, 11:45:31 am
content: G'day all.I am new to this forum and to most electronic topics also.While looking up on membrane switches i discovered eevblog has a forum and it seems to be beginner friendly so thought id ask.I am working on a little project and need some basic questions answered at my current stage, reddit is a shot in the dark and chatGPT only gets me so far.I will try to give a brief description on my project without overwhelming you all.. just yet.Function:Handheld, battery operated 6 channel power delivery deviceOutputs 12/24v (on toggle)Regural use 10(+-5) Amps (1 channel at a time)Peaks at 20 AmpsRemote to toggle channels and general feedback (leds for channel toggled, active or faulty)Body will be made out of alloy after battery quantity and pcb size is nearly set, currently at 55x55mm tube.1. Can i get away with linking 6 or even 4 18650 in series and boosting to 24v for a smaller form factor?If yes, what do i need to integrate, like overheat protection.Criteria:No fan to cool down,heat sink at mostConstant operation time of 10 minutes at ~10 amps20 amp peak operation(few minutes?)2. Best practice to switch between 12 and 24 volts, dual-output load switch?Criteria: start up defaults to 12v3. What initial faults can be seen in my idea sketch, any input/criticism welcome.I have included basic flow chart to help understand what i am talking about per pcb layout for the main board and remote (not relevant yet)QuoteThank you all who got this far!

author: m k
author_rank: Super Contributor
timestamp: April 02, 2024, 02:30:47 pm
content: How much current you can take out of a cell?If you can take 20A you need 27.5V for 550W.Eventually the thing will also warm up a bit.If you boost voltage to double you amps drop to half, but only for output.
Help needed with Xbox Series X board and capacitor  - Page 1
Forum section: electronics / beginners

author: k2Rob
author_rank: Newbie
timestamp: July 05, 2023, 07:39:17 pm
content: New here so hi all!I removed the HDMI retimer chip (NB7N) from the board and like a clown accidentally ripped off one of the pads off while doing so.I don't have a picture of the board but I have the pin circled hereI can't see any traces running from that particular pad so I'm wondering if it's used, hopefully someone can tell me.If it helps the schematics for the board are herehttps://www.dropbox.com/sh/4zo0bcwmozdns7s/AADzXQbUirWBUBo1qwP9wf1za?dl=0Second bit. I also knocked off capacitor c704 during my venture (Yes, I'm new to this xD)I did manage to find the specs of the cap in the schematics however I'm struggling to find one with the exact specs in the UK.Specs are22pf2%50vNP0Here's a pic of the capAny help would be appreciated as I'm kinda stuck with what to do now.Many thanks!

author: mayor
author_rank: Regular Contributor
timestamp: July 06, 2023, 11:25:32 am
content: Lucky for you, that last pin is not connected.You don't have to match exact specs for the cap (sorry, can't find the OnSemi datasheet for that IC online, but it looks like it's used for power decoupling). It should be easy to find a 22pF replacement that works, other capacitors on that rail are rated as low as 6.3V so anything equal or above that would also work here. What I'd be worried about is that this is an 0201 component... Not the easiest to deal with for a beginner. In your place, I'd try the console without the capacitor to see if it will work.

author: k2Rob
author_rank: Newbie
timestamp: July 06, 2023, 12:34:57 pm
content: Many thanks for the reply!That's a huge relief regarding the pad.I've found caps on Ebay that almost match the specs, only difference being that the percentage is 5% instead of 2%.Would this be okay?Edit.I seem to have found one with matching specs!https://uk.farnell.com/murata/grm0335c1h220ga01d/cap-22pf-50v-mlcc-0201/dp/2990638

author: Yuu
author_rank: Regular Contributor
timestamp: July 06, 2023, 11:37:42 pm
content: Quote from: mayor on July 06, 2023, 11:25:32 amOut of curiosity, why would they use a class 1 ceramic capacitor like an NP0 for power decoupling? I thought those were mainly used for oscillators and stuff where you want little to no variation in capacitance.
Help NFB amp - Page 1
Forum section: electronics / beginners

author: Qmavam
author_rank: Regular Contributor
timestamp: April 27, 2017, 12:26:02 am
content: Hi guys,I am trying a different amp because the last one rolled off 1.3 db at 10Mz.I built the amp on this page. I only put the first 2 transistors in and not the output buffer.This amp also rolls of 1.1db at 10 MHz. Referenced to 1MHz.http://chemandy.com/technical-articles/building-hf-amplifier/building-hf-amplifier-project-article1.htmThis amp is supposed to go out to 30MHz, I don't know if it could be my layout, my 2N3866 transistors,or if I just need to adjust the feedback,I have attached a picture of my layout.Note, I have PCB pads under the solder joints, except those that go to ground.Mikek

author: w2aew
author_rank: Super Contributor
timestamp: April 27, 2017, 01:42:30 am
content: If you didn't include the output buffer, it is likely that the output stage of this circuit isn't up to the task of whatever you connected to it to test it (output impedance too high). It might be just fine if you include the output buffer, to preserve the BW of the previous stage.

author: Qmavam
author_rank: Regular Contributor
timestamp: April 27, 2017, 02:34:55 am
content: Quote from: w2aew on April 27, 2017, 01:42:30 amI'm just monitoring it with my scope, no loading.

author: Audioguru
author_rank: Super Contributor
timestamp: April 27, 2017, 02:21:46 pm
content: The input cable of your 'scope has a capacitance to ground that cuts high frequencies when the output impedance of the circuit is higher than with the low output impedance buffer.The parts on your pcb are too far apart that adds stray capacitance.Stray capacitance around the parts also cut high frequencies.

author: Qmavam
author_rank: Regular Contributor
timestamp: April 27, 2017, 04:15:47 pm
content: Quote from: Audioguru on April 27, 2017, 02:21:46 pmYa, but, it a 300ohm... ya, but nothing! 15pf at 10 MHz is 1,061?s.2.95 volts into a 330?--1061? voltage divider is 2.3 volts out.I didn't post it here, but I have 2.95 volts output at 1MHz and 2.3 voltsoutput a 10MHz. That's a pretty close correlation!Hmm, maybe my other amp was OK.Well how the heck am I going to be able to measure this thing.I guess I just need to stick the Diode Detector on it and seehow linear my output is with frequency.QuoteI could probably tighten it up some, but if I'm going to do that, I might as well go to SMD.Back to the bench.Thanks very much for the advice, I was aware of this, but I'm so used to working at 1MHz, thatI didn't even consider that could be the problem!Thanks, Mikek
Help on Coffee Grinder Control Circuit - Page 1
Forum section: electronics / beginners

author: efr450
author_rank: Newbie
timestamp: April 10, 2015, 12:24:56 am
content: Hello all,I'm working on a project for a class and we need to control a Mr. Coffee Burr Grinder coffee grinder with a microcontroller. I accidentally damaged the circuit earlier in the semester, but we'd rather not buy a new one and waste part of our budget. I've attached photos which show the main control circuit in question, with the removed (destroyed) timer chip. We are trying to control the grinder with simple on/off function similar to the Triac circuit shown here: (see datasheet below for Triac on the board)We have the gate of the triac connected to a 120 ohm resistor, the other end of the resistor connects to the Neut terminal on the board. We first put in a 10Vpp 60hz sine wave to the input terminals (Neut and Live) and then measured the input and motor output (M+ and M-), which correctly output the same wave form as our input. We then stepped it up using 120VAC wall power, and measured both the output and input again. This time we only got a ~34Vpp output and input with the same waveforms. We measured the wall outlet with a DMM and confirmed that it was 120VAC. Just to see if it was an issue with our oscilloscope (which can handle 300VAC so we didn't think so), we decided to hook the motor up on the motor output and see if our circuit would run it. It did not. So now we are stuck on what to do next! I'm not sure what other info is relevant, but hopefully I gave enough (and if not, I can give more!).Thanks in advance for looking this over,Ethan

author: Zero999
author_rank: Super Contributor
timestamp: April 10, 2015, 10:13:05 pm
content: If you got 34Vpp on your oscilloscope then it's possible because you were using a divide by 10 probe.What's the point of the circuit? That circuit just allows a small, low current switch to control a higher current load. It's not suable for use with a microcontroller, unless the switch is some relay contacts. You can get special optically isolated TRIACs which are designed to trigger a larger TRIAC to switch a load.https://www.fairchildsemi.com/datasheets/MO/MOC3041M.pdfThere could be various reasons why the motor wouldn't run. One is the impedance of the 10V signal source is so high that the voltage drops too low, when the motor is connected.