hybridfree/eevblog-posts huggingface dataset:
I need help generating a binary signal to control a MUX - Page 1
Forum section: electronics / beginners

author: samburck
author_rank: Newbie
timestamp: June 12, 2020, 11:37:47 pm
content: Hey all!I am currently working on a synthesizer project and am relatively new to EE and so I don't have a great knowledge-base of electronic components. My goal is to have a knob or other simple interface that the user can rotate through 8 positions. For each position I want a different 3-bit binary code to be output and used to control a MUX. Through my research I have foundRotary DIP switches. These are able to be rotated and output a binary code. However, these rotary switches do not seem to have a knob or shaft for a knob to be applied to. It looks like they are intended to be rotated with a screwdriver which would not be great for my synthesizer.Does anyone know of any other ways in which I could easily generate a 3-bit binary from some sort of rotatable input? Or has anyone seen rotary DIP switches that have a knob? I would love to hear any other methods you guys might have for this! I am trying to keep my design fully analog.Thank you!

author: oPossum
author_rank: Super Contributor
timestamp: June 12, 2020, 11:50:05 pm
content: An 8 position rotary switch with a priority encoder (74147, 74148, 4532, etc) or a diode matrix.If you don't need hard stops, then a quadrature encoder and a up/down counter could be used.

author: themadhippy
author_rank: Super Contributor
timestamp: June 12, 2020, 11:53:49 pm
content: https://uk.rs-online.com/web/p/rotary-switches/6553162/It says 16 position,but the end stop is adjustable

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 13, 2020, 04:19:48 am
content: Alternatively:Use any 8 position rotary switch, a few pull down resistors and a diode matrix to encode the position to binary.
I need help identifying (a strange symbol) in the marking of an SMD component - Page 1
Forum section: electronics / beginners

author: bodzio_stawski
author_rank: Regular Contributor
timestamp: November 21, 2023, 10:22:55 pm
content: Hello!I need help identifying (a specific symbol) in the marking of an SMD component. I feel very weak in trying to identify all smd elements, especially those that have quite unusual characters in their names, so I apologize in advance if it causes emotions in the readers.In terms of dimensions, it looks exactly like sot363. There is something like acolonin the name, which makes searching for the item after marking it in Google beyond my abilities.I read somewhere that on some SMD components the figure eight marking is abbreviated with something like below:Could the sign/colon in mark "6:B 217" in the first photo mean anything special?RegardsB.

author: 807
author_rank: Frequent Contributor
timestamp: November 22, 2023, 01:15:19 pm
content: Could you let us know the equipment that it's in. It might help to narrow it down. Perhaps a photo of the whole circuit board would help too.
I need HELP identifying and locating to buy 2 components  - Page 1
Forum section: electronics / beginners

author: gica69
author_rank: Contributor
timestamp: July 22, 2025, 04:58:52 am
content: I have a quad charger that is split into 4 separate sections and one section doesn’t charge anymore. I have located what I think is a thermistor and on the shrink tube it says 125degrees C. I cut the shrink tube and it looks like a 0.33ohms fusible(?) resistor. I am including pictures of it. So, it should test at 0.4 ohms and probably go up in resistance with the rise in temp, instead it test full opened. Please let me know where I can find this. Thanks

author: gica69
author_rank: Contributor
timestamp: July 22, 2025, 05:02:31 am
content: The second component on the same board is a 6 pin IC marked as U on the board and identified as 85A50D on it. I tried to find it to no avail. I measured the voltages to the different pin and there is a picture of it. It also measures 0.5 from ground pin to the 3 pins across 1,2 and I think 3. Thanks in advance guys.

author: Uunoctium
author_rank: Frequent Contributor
timestamp: July 22, 2025, 05:39:01 am
content: I guess the 125° belongs to the shrinktube itself and indicating its max operating temperature. The shown resistor is an NB [not burnable] safety resistor. You can order them @ mouser.https://www.vishay.com/docs/28737/nfr25.pdf

author: gica69
author_rank: Contributor
timestamp: July 23, 2025, 05:14:39 am
content: That shows 0.22ohms not 0.33ohms. It's 0.33W.

author: gica69
author_rank: Contributor
timestamp: July 23, 2025, 10:08:01 pm
content: So, I think I found the chip info with the help of a member of another forum, the 50D is the week and year of manufacturing 85A is probably the type. So SC2585A seems to be it, I hope.
I need help identifying  component(3729B AKAF) - Page 1
Forum section: electronics / beginners

author: cold_zero
author_rank: Newbie
timestamp: August 08, 2024, 04:25:27 pm
content: i need help go get datasheet for ic 3729B AKAF i found it on motherboard gopro5it's marked by rectanglethank you

author: golden_labels
author_rank: Super Contributor
timestamp: August 08, 2024, 04:39:09 pm
content: Without a good quality photosof (1) the chip, (2) the chip and its neighbourhood, nobody can tell much. May be anything.For example the first result while searching for phrase ‘3729B AKFA’: AMS AS3729B “8A Power Stage”. The markings described in Fig. 15 (p. 12) of the datasheet are matching your description.

author: cold_zero
author_rank: Newbie
timestamp: August 09, 2024, 06:55:50 am
content: you are right , sorry it's my bad i edit the post and add images

author: golden_labels
author_rank: Super Contributor
timestamp: August 10, 2024, 05:33:39 pm
content: The lime square marking hides all the traces, but it seems to be roughly matching (Fig. 3 on p. 3, rotated by 180°). The presence of inductors and fat traces also suggests this is a power supply chip.
I need help identifying some components("DDR", "SAF") - Page 1
Forum section: electronics / beginners

author: cold_zero
author_rank: Newbie
timestamp: June 08, 2024, 05:48:42 am
content: I need help identifying some components on the motherboard of a GoPro camera. I have taken pictures of them.The first component is labeled "DDR" and is connected to the camera lens.The second component is labeled "SAF" and is connected to the USB IC. One of its pins has 5 volts.I have attached the photos of these components.Thank you

author: exmadscientist
author_rank: Frequent Contributor
timestamp: June 08, 2024, 06:23:31 am
content: SAF isTPS78218DRV.DRR isTS3USB3000MRSER.

author: cold_zero
author_rank: Newbie
timestamp: June 08, 2024, 07:16:40 am
content: thank you
I need help identifying what I think is a resistor  - Page 1
Forum section: electronics / beginners

author: killerkevdog
author_rank: Newbie
timestamp: March 15, 2025, 10:37:02 pm
content: I bought this (EN-SW10g-001) Eagle Eye 8 port Gigabit POE+ switch, new online. It never showed any lights or any signs of life. I got a replacement switch and decided to see if I could find out what the problem was on this one. I looked at the new switch and it has a completely different power supply board. There are two boards underneath the cover. The power supply board has a component that is blown. See Pics, It is labeled (R42). Im guessing its a resistor. Is there any way to figure out what it is? Using a multi-meter? Does anyone know where I could find the right component? Could I use an external DC power supply and splice it in? Any thoughts would help.Thank you

author: Whales
author_rank: Super Contributor
timestamp: March 15, 2025, 11:24:16 pm
content: That resistor looks like it's for passing a high current. It might be a current shunt resistor or a fusable resistor. I do not know of a way of finding the resistor's value other than trying to find other boards of the same model. It could be anything from 1milliiohm to 100milliohm.It's almost a guarantee that the resistor is a victim, not a cause. Something is shorted in the circuit. Often this is a mosfet, rectifier or transformer. If you don't fix this then the resistor (or another part) will immediately blow again.Is this a bit of copper shorting this connector?I love how crooked those big packages are. They be groovin.

author: NPG
author_rank: Contributor
timestamp: March 16, 2025, 12:04:55 am
content: I agree, that piece of copper or whatever it is looks out of place.If whatever is on the other side of the board in that place is a cap, resistor, or diode, then the piece of material shouldn't be on the bottom.

author: temperance
author_rank: Super Contributor
timestamp: March 16, 2025, 12:11:04 am
content: The power supply controller is a TEA8918 which is a PFC+LLC controller. The burnt resistor is the PFC section current sense resistor.

author: golden_labels
author_rank: Super Contributor
timestamp: March 16, 2025, 02:41:12 am
content: Thanks for good quality photos, killerkevdog.That salmon-colored thing is not copper. It’s translucent, as you can see by the shadow it casts.Perhaps it is some adhesive, that got there by accident? No idea, if it should be there. But I doubt it would pass any current significant enough to blow up a resistor.If user temperance (above) is right, then I’d not continue to simply replacing it. Rather remove it, and check if there is no shorts to ground. If not, also check the outputs and whatever this power supply was powering. No point in putting a new resistor, if it’s going to be blown up too.

author: temperance
author_rank: Super Contributor
timestamp: March 16, 2025, 01:58:39 pm
content: QuoteThat resistor will blow up again if you only replace the resistor. The half bridge LLC is probably broken and shorted the PFC output.
I need help on how to calculate resistances of this circuit - Page 1
Forum section: electronics / beginners

author: Vex
author_rank: Newbie
timestamp: December 04, 2018, 11:44:37 am
content: Hello Guys,The circuit is shown in the attachment. The known values are resistances R1, R2, R3, R4, voltages U1, U3, U2, and current can be measured on A1 and A2.The switches can be controlled (all closed, all open or one closed, one open). The resistances R5, R6 are unknown.Can we somehow calculate these resistances with this known values and controlling the switches, and if we can, what are the equations for calculating it?Thank you.

author: ArthurDent
author_rank: Super Contributor
timestamp: December 04, 2018, 01:23:11 pm
content: Ah, looks like another homework assignment problem. First, with the switches open you can state a general equation for the current in the circuit circuit U1/R5/R6 as IR5=U1/(R5+R6). Then close SW1 and knowing the current added (A1) through R5 start getting values. Do the work.

author: kulky64
author_rank: Regular Contributor
timestamp: December 04, 2018, 07:57:17 pm
content: 1. SW1=open, SW2=closed -> measure current I_A22. SW1=closed, SW2=open -> measure current I_A13. R6 = (U1*(U3-U2-U1+(R1+R3)*I_A1-(R2+R4)*I_A2)) / (U3*I_A2-(U1+U2+(R2+R4-R1-R3)*I_A2)*I_A1)R5 = -R6*(U1+U2+(R2+R4)*I_A2) / ((R2+R4+R6)*I_A2+U2)Verify with simulation if it is correct.

author: Vex
author_rank: Newbie
timestamp: December 05, 2018, 04:10:29 pm
content: Thank you, i did the simulation and the results are correct!If you have time, can you please explain in a little more detail how did you get this equations?Thank you.

author: kulky64
author_rank: Regular Contributor
timestamp: December 05, 2018, 04:47:09 pm
content: Let's consider first the case when SW1=open and SW2=closed. Leftmost branch of this circuit is completely dead in this case and A1 reads zero. Now you have effectively only two sources in the circuit and A2 shows some current. Derive the expression for this current using your preferred method (I used superposition principle):I_A2 = f(R1, R2, R3, R4, R5, R6, U1, U2, U3)Well, R1, R3 and U3 will not appear in this function for obvious reason, but I left it as most general case.Then consider the case when SW1=closed and SW2=open. Now rightmost branch is completely dead and A2 reads zero. You have again effectively only two sources in this circuit and now derive equation for current through A1:I_A1 = f(R1, R2, R3, R4, R5, R6, U1, U2, U3)Now R2, R4 and U2 are irrelevant a will not appear in this equation.You have now system of two equations with only two unknown values of R5 and R6, because you measure I_A2 and I_A1 and the rest is given. Solve this system of equations and done.
I need help on what this component is - Page 1
Forum section: electronics / beginners

author: Matt1234
author_rank: Newbie
timestamp: June 16, 2020, 10:15:50 am
content: Hello. My name is Matthew and I am a 1.st grade electrical engineer. Recently I used the soldering machine for the first time and I opened up my old TV to get some parts for my prototypes. I desoldered all of the parts that I believed were working (checked with multimeter and others). I have collected some nichicon and rubycon capacitors that were in the good condition, checked them and they are working, no electrolyte leakages. And then I have found this yellow object which I can not find out what it is. I really dont know what is this, a varistor or a X1 Y1 capacitor.The front part says: (Not really accurate, some letters are inside a circle and other)MNS-A331 SUSU S F1H23 NBack part says:DE +SL22Y1=250 VX1=440 VImage:https://imgur.com/a/JHLhlKYI would also like to know how can I check if these components are working, and how much they cost? Sorry for bad English, and thanks in advance!

author: madires
author_rank: Super Contributor
timestamp: June 16, 2020, 11:10:44 am
content: It's a class X1/Y1 ceramic capacitor with 330pF (33 * 10^1). If you buy a new single one you will pay about EUR 0.20. For checking salvaged parts I'd recommend to get an inexpensive Transistortester / component tester (they are all over the place). But you can also do some basic checks with a DMM. If you search the web you'll find plenty of guides about testing components with a DMM.

author: Matt1234
author_rank: Newbie
timestamp: June 16, 2020, 11:18:35 am
content: Thank you for a clear and in-depth explanation!
I Need Help Recognizing Parts - Page 1
Forum section: electronics / beginners

author: sanyus_29
author_rank: Newbie
timestamp: January 22, 2023, 02:29:41 am
content: Hola a Todos[ Specified attachment is not available ]

author: Psi
author_rank: Super Contributor
timestamp: January 22, 2023, 02:38:22 am
content: It's customary to actually ask a question when making a new thread.

author: IanB
author_rank: Super Contributor
timestamp: January 22, 2023, 02:40:30 am
content: It's a circuit board with a reference number of DW-H206-01A and a revision date of 6th October, 2013.

author: inse
author_rank: Super Contributor
timestamp: January 22, 2023, 07:25:26 am
content: I‘m actually struggling with U5 to finish the BOM

author: Terry Bites
author_rank: Super Contributor
timestamp: January 22, 2023, 02:25:25 pm
content: Did you find it in a dumster, is it a random PCB?What does it do, what is it from, who makes it?The potatocacm.blr image isn't helping.My mindreading organ has just burst so its going to be a while.

author: mariush
author_rank: Super Contributor
timestamp: January 22, 2023, 05:04:44 pm
content: Check what's written on the IC.Looks to me like some sram / sdram or Flash chip or maybe some EMMC chip (flash memory with built in controller)The picture is too blurry to see text on the chip but the bar to the left of the text on the chip makes me think of Intel chips .. see picture of old Intel NAND chips on this SSD:https://www.legitreviews.com/lsi-demonstrates-ssds-with-toshiba-19nm-intel-20nm-nand-flash_13315

author: themadhippy
author_rank: Super Contributor
timestamp: January 22, 2023, 06:04:25 pm
content: Looks like a thingamebob from a whatchamacallit,best to check the oojamaflip first.
I need help understanding a SMU voltage measurement circuitry - Page 1
Forum section: electronics / beginners

author: DanielDlouhy
author_rank: Contributor
timestamp: April 22, 2024, 05:15:18 pm
content: Hello everyone!I am working on designing my own Source Measure Unit and I was looking how to make the voltage measurement circuitry. The output is floating, so it has to be a differential measurement. Because my biggest inspiration is the mighty Keithley 236, I looked there for inspiration. And I don't seem to understand the circuit fully... Because in my head it can't work up to 110 V, as it should. Even the simulator (falstad - website) didn't help.I also found a simplified schematic made by Jaromír Sukuba, that he used in his diy SMU. (see attachment)https://github.com/jaromir-sukuba/J-SMUJust to clarify, the 15V0+ and 15V0- are floating. But still, the voltage difference between SEN- and SEN+ is up to 110V and I don't know how this circuit is able to measure that. When the input op amps can't handle more that about +-15V and it's even clamped using diodes D4 and D5. I know it has to be something with the floating power supply, but I can't quite understand it, can someone help me understand it, please?Thank you in advance!

author: jaromir
author_rank: Unknown
timestamp: April 22, 2024, 05:56:29 pm
content: Hi there.Potential on SEN+ is close to +-15V ground potential (the difference being votlage drop on current sense resistor)Potential on SEN- is negative with respect to +-15V ground when output voltage is positive. +-15VO ground potential is floating near SEN- potential. Voltage on U11 output follows its input (that is, SEN- voltage), and is divided down using R29/R28 divider, and therefore brought to levels within +-15V range.My name is Jaromir Sukuba.

author: DanielDlouhy
author_rank: Contributor
timestamp: April 22, 2024, 06:16:22 pm
content: Thank you very much, or should I say Děkuji mockrát!I didn't realize that SEN+ is so close to the ground potential, now it makes much more sense... I will take a look at this more, and I may write againBut for now, a big thanks!And I am really sorry that I misspelled your name, I will fix it right away.

author: MathWizard
author_rank: Super Contributor
timestamp: April 23, 2024, 12:36:49 am
content: So what do people test with high voltages like that? And do SMU's use AC sweeping voltage like a Curve Tracer ? I gather a SMU can be a current or voltage, sink or source, is it basically just DC tho, and people still use the HV for testing transistors/diodes or even leakage testing caps?I copied a Heathkit Curve Tracer, but still never finished the op-amp section, and now I want to use a micro-controller with it. I'd love to try to copy an old, low voltage version of these, or just leave out most the HV section.
I need help with a "one hour timer" circuit - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: August 27, 2018, 10:09:37 pm
content: Hi there.While reading the Art Of Electronics (3rd edition) I looked at the nice circuit at page 467,fig. 7.65using anltc6991and some other components to create an "automatic shutdown" of the circuit after one hour from its power up.I thought that was neat and tried doing my own version, only to make it go for half an hour. Only my circuit does not work at all. So, after three days of trial and failure I came here for support.Here's what I have different:Instead of the LVC2G02 I have connected two NORs from a 74HC02N I had aroundInstead of the LVC1G04 I used one inverter from a 74HC04 I had aroundI used a 1M resistor as R5 (as suggested in the LTC datasheet) accurately measured among the ones I haveI connected 880K of resistance, accurately measured (680k+ 2*100K series) as R4 – note that this is a measure I adopted in the later stages of the circuit, since nothing else worked – in order to be as much compliant to the datasheet as possiblecalculated and put in an 82K resistor as R3 to achieve my resultused a different p-fet, anIRLIB9343which is the only p-fet I had aroundhooked up an LED to the fet drain to see when the cycle is throughWell after all of that the result is that well after 40~50 minutes, the circuit is still on and does not want to switch off!Do you think I made any mistakes? If you think I should post images about what I did, I'll pretty 'em up and do it when I can (it's night here unfortunately).Thanks to anyone even only for reading this

author: Signal32
author_rank: Frequent Contributor
timestamp: August 27, 2018, 11:19:07 pm
content: Hello,Not sure exactly what is wrong but first step is to get the ltc6991 oscillating at let's say 1HZ frequency. Try to power a red led directly(through a resistor). Try to get that going and then you can continue with adding the MOSFTET and then the gates.Signal32

author: Moriambar
author_rank: Unknown
timestamp: August 28, 2018, 06:16:19 am
content: You're right... I should start simple: nice idea! I was so frustrated that I did not think about it.EDIT: yes, starting it simple made me solve everything in around five minutesThank you!
I need help with Half bridge driver IC IR2184 - Page 1
Forum section: electronics / beginners

author: Carabus
author_rank: Contributor
timestamp: April 12, 2022, 04:01:08 pm
content: What do Vb and Vs do? how it affects the circuit?Here's how I imagine the driver:https://ibb.co/gJPpk9phttps://ibb.co/G0W017Dthe top MOSFET would need 24v, and the bottom one 12v, right?also, how do I configure (if it's possible) for one output to use 24v instead of 12v, and lastly does this ic have some kind of prevention of shoot-throughs?

author: Carabus
author_rank: Contributor
timestamp: April 12, 2022, 04:12:19 pm
content: I might have figured it out in multisim, is it for setting the bootstrap voltage of the one output which drives mosfet which needs to be bootstrapped?

author: Sauli
author_rank: Contributor
timestamp: April 12, 2022, 04:39:47 pm
content: The way you 'imagine' to use it won't work. Unless you have a third power supply higher than 24V and the 12V power supply can sink the load current.Actually the case where the lower MOSFET conducts works. But for the upper MOSFET to conduct you need to supply VB with a higher voltage than VS is. The capacitor in the typical connection of the data sheet won't last long to keep the upper MOSFET conducting. If you had a voltage higher than 24V you could connect it directly to VB to keep the MOSFET conducting.Typically this chip is used to change the current direction in a motor winding, and two chips are needed for that.The dead time of IR2184 is 500ns, that is the time from shutting down one MOSFET to opening the other.

author: Carabus
author_rank: Contributor
timestamp: April 12, 2022, 04:45:43 pm
content: Thanks for the reply, I'll use a capacitor voltage divider with big value capacitors, or if I get my hands on a dual power supply.
I need help with wirin g a switch - Page 1
Forum section: electronics / beginners

author: Hextejas
author_rank: Frequent Contributor
timestamp: September 02, 2023, 02:59:29 pm
content: The switch is a Westek 758FPCT and dumb old me took a picture of the inside of the box but got the wrong side of the wires.So here goes:The switch has 3 wires labeled as such1) Red-Load2) White-Neut3) Black-Lineand the box also has 3 wires colored as:1) Green2) White3) BlackI have been told to wire accordingly:White to WhiteBlack to BlackandGreen to RedWhat say you all ?and thanksDid I say that electricity scares me ?

author: donlisms
author_rank: Frequent Contributor
timestamp: September 02, 2023, 03:27:58 pm
content: Electricity *should* scare you!(Sorry I don't have an answer.)

author: BillyO
author_rank: Super Contributor
timestamp: September 02, 2023, 06:00:09 pm
content: Can you post good detailed pictures?It does not sound right to me. In the US green is normally ground. Does the green wire go to the light you intend to control?Here is a PDF that shows how it is to be used.https://www.gtsanders.com/UserFiles/septemberdocuments/758CT_INSTRUCTIONS.pdf

author: Hextejas
author_rank: Frequent Contributor
timestamp: September 02, 2023, 08:16:25 pm
content: Topic solved. I got help from an electrician friend of mine.

author: BillyO
author_rank: Super Contributor
timestamp: September 02, 2023, 08:50:58 pm
content: Best way to go anyway. What did the solution turn out to be?
I need this connector but can't find it - Page 1
Forum section: electronics / beginners

author: VEGETA
author_rank: Super Contributor
timestamp: March 27, 2024, 08:29:31 am
content: HelloI need this connector as a PCB through hole one:https://www.fullyretro.com/images/items/74008459-item-big-SDC-REPCONTB-A-1.jpghttps://www.raphnet-tech.com/products/dreamcast_usb_circuit/dc_connector_pinout.pnghttps://tovideogamesupply.com/wp-content/uploads/2023/12/dreamcast-controller-port-board-3.jpgit is for sega Dreamcast, I searched and found people calling it maple connector since it uses a serial bus called that. however, i could not find it anywhere so i think it is proprietary??alibaba and chinese suppliers seem to have it but not in pcb friendly through hole.how can i get this to be used in pcb soldering it at right angle similar to original controller board?regardsEDIT: i contacted alibaba supplier and he sent this:https://imgur.com/a/sre6PSIthis is the best i could find.i need to be able to make a board with same form factor as original controller ports board (with my extra components there)... meaning the connectors must be at right angle. this connector as you saw is not right angle.a quick solution came to me is to make small pcb for the 4 connectors, then put right angle connectors on it. this way i can install it on the new flat board.for your opinion.
I need to figure out some components. - Page 1
Forum section: electronics / beginners

author: Savetheday
author_rank: Regular Contributor
timestamp: September 20, 2021, 07:44:47 am
content: HiI found some components that standing on the table I googled but no luck.What is this for?

author: Savetheday
author_rank: Regular Contributor
timestamp: September 20, 2021, 07:49:09 am
content: And those

author: capt bullshot
author_rank: Super Contributor
timestamp: September 20, 2021, 07:52:47 am
content: Film capacitors, KS type (polystyrene), rated 160V, probably 12nFGood ones for audiophools or if you need low losses and tight tolerancesEdit: the other ones are ceramic caps, nothing special

author: Savetheday
author_rank: Regular Contributor
timestamp: September 20, 2021, 08:13:20 am
content: Thanks. Why do they put H at the end instead of f or n strange!

author: ledtester
author_rank: Super Contributor
timestamp: September 20, 2021, 11:16:14 am
content: Capacitance is usually stated in picofarads and the suffix often some other aspect of the device -- like a temperature or tolerance rating.Example datasheet:https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Capacitors%20PDFs/ECK-DNA.pdf

author: Savetheday
author_rank: Regular Contributor
timestamp: October 02, 2021, 07:11:41 pm
content: and what is this?

author: Jwillis
author_rank: Super Contributor
timestamp: October 03, 2021, 02:09:34 am
content: Those last pictures all look like coil inductors . Value unknown .

author: capt bullshot
author_rank: Super Contributor
timestamp: October 03, 2021, 07:58:27 am
content: SMT inductors, probably in the 470nH ... 22uH ballpark

author: srb1954
author_rank: Super Contributor
timestamp: October 03, 2021, 10:49:37 am
content: Quote from: Savetheday on September 20, 2021, 08:13:20 amIt denotes the tolerance codeF 1%G 2%J 5%K 10%H is very rarely used as a tolerance code: it is either 2.5% or 3%
I need to find a 10 position DIP switch that can handle 12-24VDC / VAC 1amp - Page 1
Forum section: electronics / beginners

author: dw8000
author_rank: Contributor
timestamp: September 17, 2012, 02:17:59 am
content: I am designing a very simple circuit that is going to take voltage @ 12-24VDC / VAC 1amp in one side and out the other through a 10 position open/close switch of some sort. Also was hoping to be able to pass analog USA telephone line as well @ 52VDC 35ma and ring voltage 90VAC 13ma. Well the design is simple but there is a flaw. The 10 position DIP switch I would like to use shows switching capacity at ratings below the objective. I want to keep the cost below $2 USD per 10 position switch. Any ideas?24V 25mahttp://www.mouser.com/ProductDetail/NKK-Switches/JS0108AP4-S/?qs=sGAEpiMZZMtadyunAd%252b8Z6LGl%252bMzOERK

author: Flunze
author_rank: Regular Contributor
timestamp: September 17, 2012, 03:56:12 am
content: It will be impossible OR you will not be able to pay such a high price. Better use a circuit, that can use low current signals like throught that, that will switch your other stuff on. Or, the last piece, that makes noise: Relays.
I need to find a good low voltage cutoff circuit for LiPo batteries - Page 1
Forum section: electronics / beginners

author: Razor512
author_rank: Regular Contributor
timestamp: May 26, 2015, 05:17:07 am
content: Hi, I have a few LiPo batteries which have their own built in protection circuits, but the low voltage protection of the battery seems to kick in around 2.75V, but I am not comfortable discharging them them that far. I would instead like to have a cutoff at around 3.2V instead.The problem is that I will be using it to power a device that had previously used 3V non rechargeable lithium batteries (I have regulation taken care of using a boost-buck converter), and it will take batteries down to 2.5V, thus if used with used with the LiPo cell, it will always drain the battery to a point where the protection circuit kicks in.I am using some cheaper shenzhen market 4000mAh LiPo cells which is another reason why I am not comfortable with draining them to 2.75V.I am mainly looking for a power efficient way to implement a low voltage cutoff, with the intention of powering a device that will only consume around 50mA of power.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: May 26, 2015, 05:35:44 am
content: You can just get one of these 1$ modules for charging and discharging the lipo cells. I use them all the time on mybatteries. They cut the power around 3.2 V (Not sure ....). They also can monitor the charging with USB.I can also say that G&C is a very reliable and fast (?) ebay seller.http://www.ebay.fr/itm/1pcs-5V-MICRO-USB-1A-Lithium-Battery-Charging-Protection-in-one-Board-Module-/300919267742?pt=LH_DefaultDomain_0&hash=item46102fa19e

author: jct
author_rank: Contributor
timestamp: May 26, 2015, 05:40:28 am
content: Look at TPS3809 (from Texas Instruments), alternative MAX809 from Maxim; available in various voltages from 2.5 up to 3.5. Attached is just a "Battery OK" and "Low Voltage" indicator, but will give you an idea how to impliment in your application.

author: Razor512
author_rank: Regular Contributor
timestamp: May 26, 2015, 02:30:07 pm
content: For the $1 units, I was really interested in them, but all of them seem to have a low voltage cutoff of 2.5V which will make the battery hit its own 2.75V cutoff.I might have to build one if there are no modules. I just hope I don't end up with a situation where the protection circuit uses a ton of power.A 2.75V cutoff just makes me uncomfortable, it just seems way too low for such a battery.

author: sparx
author_rank: Contributor
timestamp: May 28, 2015, 07:11:55 pm
content: Quote from: Razor512 on May 26, 2015, 02:30:07 pmHave a look at the datasheet (if available for the chip used) - maybe changing a resistor will change the cutoff.
I need to install ICflash to Vu solo decoder - Page 1
Forum section: electronics / beginners

author: albeixon
author_rank: Newbie
timestamp: May 18, 2015, 10:38:16 am
content: What programmer need to put Ic Flash TOSHIBA J93687 Taiwan 13429AE3 TC58NVG1S3ETA00 , in mi decoderthank you
I need to make sure I understand how the ULN2003 Darlington Array works - Page 1
Forum section: electronics / beginners

author: engineheat
author_rank: Frequent Contributor
timestamp: January 19, 2018, 11:08:46 am
content: Here is a schematic of the ULN2003 being used to drive the 28-byj48 stepper motor (unipolar).Here is a schematic of the internals of the ULN2003:So basically, power (5V) is delivered to the stepper by the red line (connected to the COM of ULN2003). Drive signals from the microcontroller goes into the IN1, IN2...IN4 pins of the ULN2003, which allows current to flow through the respective channels of the Darlington. This is the current that flows through the motor and allows it to turn. This current goes from the OUT pin of the ULN2003 and flows to the GND pin of the ULN2003.The OUT pin is essentially the collector, and the emitter is essentially the ground according to the ULN2003 schematic. There is a free wheeling diode at the COM and its purpose is to allow current to flow back to motor in a cycle once current gets shut off in the channel. This is because the motor has inductance and current cannot drop to zero instantaneously.Did I understand it correctly?Thanks

author: danadak
author_rank: Super Contributor
timestamp: January 19, 2018, 11:46:38 am
content: Yes.Regards, Dana.

author: engineheat
author_rank: Frequent Contributor
timestamp: January 21, 2018, 04:14:16 am
content: So if I think of each Darlington pair as a NPN, then is it in Saturation mode when there is a signal from the microcontroller, and Cutoff mode when there are no signal from the microcontroller?thanks

author: Zero999
author_rank: Super Contributor
timestamp: January 21, 2018, 09:08:57 am
content: Quote from: engineheat on January 21, 2018, 04:14:16 amYes.

author: MarkF
author_rank: Super Contributor
timestamp: January 21, 2018, 10:16:47 am
content: Quote from: Hero999 on January 21, 2018, 09:08:57 amBe aware. There are different versions of the chip for different input logic levels:The ULN2002A is designed specifically for use with 14-V to 25-V PMOS devices. Each input of this device has a Zener diode and resistor in series to control the input current to a safe limit.The ULN2003A and ULQ2003A have a 2.7-k? series base resistor for each Darlington pair for operation directly with TTL or 5-V CMOS devices.The ULN2004A and ULQ2004A have a 10.5-k? series base resistor to allow operation directly from CMOS devices that use supply voltages of 6 V to 15 V.The required input current of the ULN/ULQ2004A is below that of the ULN/ULQ2003A, and the required voltage is less than that required by the ULN2002A.There is also the ULN2803A in a bigger package with 8 pairs.
I need to stop scrapping TVs - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: March 09, 2018, 05:17:36 pm
content: I have 3-4 TV PCBs from the 90s-2010 to scrap, and I bet I have taken apart 4 over the past 3 years. Good source of power resistors, a few big caps, inductors, heatsinks, sometimes relays, flyback transformer, sometimes RF cans, magnet wire in the yoke, maybe even the PCB if I cut it up to use small sections for other stuff.IDK...I'm about to get another 1, oh well that's an excuse to de-solder 1 of the above.

author: james_s
author_rank: Super Contributor
timestamp: March 09, 2018, 07:06:18 pm
content: The CRTs are useful and getting scarcer all the time. If you know anybody local who collects vintage arcade machines they probably know someone who can use the tube. TV tubes are good candidates because they rarely have phosphor burn, something that arcade monitors are notorious for.This is one that I replaced recently, the gun was shot too, even after a rejuve attempt the brightness had to be cranked up all the way to obtain a barely usable picture.
I saw some of those perma proto boards and made up one in eagle... - Page 1
Forum section: electronics / beginners

author: alank2
author_rank: Super Contributor
timestamp: January 21, 2016, 03:26:01 am
content: That fits the cheapo $9.90 5x5cm form factor from iteadstudio.I just threw these together tonight so let me know if you see something that can be improved.It has a couple of mounting holes, an extra area to do 2x3 100 mil header (for an ISP, etc.), and the top/bottom power buses are connected.I've made a 5x10cm ($14.90 for 10) and a 10x10cm ($19.90 for 10) variations as well. They have much more double row header capability.I thought some of these might be handy for putting together something quick without much work. I've never been very good at routing on those other boards where the nets are defined...Suggest any improvements you can think of...

author: alank2
author_rank: Super Contributor
timestamp: January 21, 2016, 01:05:00 pm
content: 5x10 and 10x10

author: alank2
author_rank: Super Contributor
timestamp: January 22, 2016, 01:15:37 am
content: I was also thinking, one could make a version with room for a single SOIC20, TQFP32, TQFP44, TQFP64 to support some SMD packages too. I ordered some 5x5 ones from elecrow today with white mask to see how they will turn out. I can move a couple of my "tester" breadboards for testing things off the breadboard and onto something real.
I stuffed up 250 times - Page 1
Forum section: electronics / beginners

author: 24602
author_rank: Contributor
timestamp: April 04, 2025, 11:32:08 am
content: I stuffed up 250 timesSo sent to fab 250 pcbs with an incorrect way of switching/ dimming these LEDs from a ESP32 (Via header on left). By High side driving these LEDs using these particular mosfets results in a working but very dim LED.Schematic AttachedThe mosfet is a SOT23 part.Is there a drop in part replacement to get this working? Trying to avoid having to bin a bunch of boards.(5x RGBW LEDs)

author: xavier60
author_rank: Super Contributor
timestamp: April 04, 2025, 11:58:10 am
content: Try an NPN BJT.

author: Andree Henkel
author_rank: Regular Contributor
timestamp: April 04, 2025, 12:00:54 pm
content: or a PMOS FET / pnp bipolarneeds ofcourse inverting the control voltage (output level of µC in firmware)

author: Ian.M
author_rank: Super Contributor
timestamp: April 04, 2025, 12:02:59 pm
content: This has come up before. IIRC source/drain pinout swap SOT-23 MOSFETs are vanishingly rare, and *IF* you find one, you still have the problem of the gate pulldowns, which obviously should be pullups. Also you'd need a 5V logic high level but the ESP32 PWM is only 3.3v.A better solution would be to create a little interface board to provide approx 10V gate drive, which will let those high side N-MOSFETs work just fine.

author: 24602
author_rank: Contributor
timestamp: April 04, 2025, 12:07:13 pm
content: Quote from: Ian.M on April 04, 2025, 12:02:59 pmThanks yeah, if I have to create a add-on board would be better of just re spinning these problematic LED boards

author: 24602
author_rank: Contributor
timestamp: April 05, 2025, 10:46:20 am
content: Hi All, Ive redone the schematic let me know if there's any problems before I send to fab
I think I'm having a problem with one of my power supplies. - Page 1
Forum section: electronics / beginners

author: cvriv
author_rank: Frequent Contributor
timestamp: July 08, 2016, 09:05:13 am
content: I bought two DP832's and one of them is doing something I'm pretty sure it shouldn't be doing.I set them both to 1V and 0A. They should both show that there's no output, zero's across the screen. One power supply has all three channels doing just that and the other power supply has two channels at 1.01V with the third channel showing no output. I measured the out of the two 1.01V channels and measured 1.002V.I'm pretty sure there's something wrong with the one power supply. Can you please confirm before I contact tequipment. Thanks.

author: cvriv
author_rank: Frequent Contributor
timestamp: July 08, 2016, 09:45:09 am
content: I did a quick search and found out that it's a hardware issue. I already contacted tequiment about receiving a replacement.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 08, 2016, 12:12:48 pm
content: The 0 mA current setting is not reliable, because of offsets. Depending on the unit the 0 mA could be slightly positive or negative. So this will either effectively turn off the channel (like the one unit) or could deliver a small current (e.g µA range). Both would be OK and usually within specs. It's just a setting not suitable for testing, at least without a load. With a load (like 100 Ohms) there should be only a small current (tolerance).

author: cvriv
author_rank: Frequent Contributor
timestamp: July 08, 2016, 03:46:22 pm
content: Well, of all 6 outputs, 4 of them go to 0V and two remain at 1.01 volts when I set the current to 0mA. The two that remain at 1.01V say "On UR".Ok, so I set a pot to 100 ohms. I set one of the so called bad channels to 0V and 0mA and one good channel to the same. The good channel measures -1mA and the bad channel measures 8uA. You are saying this is ok?If I set the current to anything but 0A, no matter what voltage I set it to, it's always 0.01 volts higher than what I am setting. This is fine? Ugh, I don't don't like that. I'm to much of a perfectionist to be ok with that. I'm suppose to call Rigol when they open. This is what tequipment told me to do first. Should I even call them now?

author: tautech
author_rank: Super Contributor
timestamp: July 08, 2016, 04:22:46 pm
content: Quote from: cvriv on July 08, 2016, 03:46:22 pmNo it's not fine.Either a FW bug or a HW problem.Get it sorted or you'll never trust it or sleep well at night.You've got one that appears to be fine, give the faulty one the boot. Period.

author: cvriv
author_rank: Frequent Contributor
timestamp: July 08, 2016, 06:14:39 pm
content: Ok. Well, tequipment said I first had to call Rigol and have them do whatever they are going to do?!?!? I sent them pics via email after speaking with them over the phone.Don't know why the two pics are tilted. Geeeezus does anything on my end work
I want to buy a bench oscilloscope ~ - Page 1
Forum section: electronics / beginners

author: goethert
author_rank: Contributor
timestamp: August 15, 2017, 08:35:10 pm
content: My first ever post.Oscilloscope is for the general hobby electronics. My budget is $1000 maximum, but not less than $800. Any suggestion?I have a plan to slowly build an electronics lab. Is there an equipment and material list that I can follow to buy? Thanks.

author: tautech
author_rank: Super Contributor
timestamp: August 15, 2017, 08:45:28 pm
content: Welcome to the forum.The place to start looking is:https://www.eevblog.com/forum/testgear/digital-oscilloscope-comparison-chart/When you have some *must have* specs come back with more questions.

author: hermit
author_rank: Frequent Contributor
timestamp: August 16, 2017, 01:07:53 am
content: I've read some that say they get way more use out of a logic analyzer than a scope now days. I'd say 'build your interest' first and let the lab equipment follow that.Seriously. What is your interest? Do you have any projects in mind? Dropping a grand on a scope is not really the way to start until you know what you need that scope to do. I just got one for $35 used that does way more than I actually need it to do as a hobbyist.

author: goethert
author_rank: Contributor
timestamp: August 16, 2017, 07:09:45 am
content: Quote from: hermit on August 16, 2017, 01:07:53 amanywhere to find an equipment list for an electronics lab?Sent from my LON-L29 using Tapatalk

author: rstofer
author_rank: Super Contributor
timestamp: August 16, 2017, 03:39:43 pm
content: Quote from: goethert on August 16, 2017, 07:09:45 am

author: goethert
author_rank: Contributor
timestamp: August 17, 2017, 10:46:25 pm
content: Very useful video. Thanks.I believe there is a text version of the list somewhere?

author: Brumby
author_rank: Unknown
timestamp: August 18, 2017, 12:50:05 am
content: That video was 6 years ago. Dave has done a follow-up video last year where he tries to do the same thing on a tight budget of $300.You may not be interested in the low budget side of things, but it is useful to see thetypeof gear he suggests.....
I want to capture a square wave drop out on my scope - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: October 11, 2018, 06:34:31 pm
content: I have a Si5351a synthesiser chip that is supposed to give out 180 degree out of phase 137kHz square waves from pins CLK9 and CLK1. I believe the firmware that runs it may have a bug as I see the occasional drop out, very brief and random. I THINK there may be a higher frequency, lower amplitude signal showing during these glitches. My scopes are quite basic, a Dataman 526 150 MHz USB scope and a Philips PM3380 100 MHz "combiscope" that can be switched from analogue to digital. My knowledge of their usage is pretty rudimentary OI am afraid, although I know the basics.I also have an elderly HP scope a HP 54501A 100MHz 4 channel jobbie.https://www.dataman.com/downloads/dl/file/id/40/product/35/dataman_520_series_manual.pdfhttps://dam-assets.fluke.com/s3fs-public/pm33xx__umeng0200.pdfhttp://ftb.ko4bb.com/manuals/82.70.254.222/HP_54501A_Digitizing_Oscilloscope_Front_Panel_Operation_Reference.pdfI have never attempted to catch a dropped waveform, could anyone suggest if any of these scopes are capable of showing what happens during these glitches please? thanks.

author: jmelson
author_rank: Super Contributor
timestamp: October 11, 2018, 06:57:45 pm
content: Look for missing pulse triggering. Possibly your scope in digital mode has such a trigger option. This is something that the fancier logic analyzers can usually do.Or, set up a trigger requirement where if it has a pulse on one input but no complementary pulse on the other, it triggers. I think I know how to do this on a Tek logic analyzer, not sure on anything else.Jon

author: tautech
author_rank: Super Contributor
timestamp: October 11, 2018, 07:47:59 pm
content: A Period trigger should do this.
i want to know what a coil with 3 connections is. - Page 1
Forum section: electronics / beginners

author: Eamonn58
author_rank: Newbie
timestamp: December 20, 2021, 10:27:34 pm
content: I am trying to reverse engineer an alarm pizo circuit. Its the loudest I have found with a 9 volt battery.The circuit has a CD 4069UBE inverter chip with some resistors capacitors transistors.There is also a coil with 3 connections but I cant find a coil with 3 connectors and don't know what its called. It did have a plastic cover over it (similar to an electrolytic capacitor) which hadsomething like 865K written on it. I removed it and cant remember the actual number.I am quite a novice at electronics but realise how useful it is for making cool products.

author: langwadt
author_rank: Super Contributor
timestamp: December 20, 2021, 10:32:29 pm
content: tapped inductor?similar to end of this page,https://itectec.com/electrical/electronic-how-does-the-component-alarm-boost-three-pin-inductor-make-a-piezo-buzzer-louder/

author: james_s
author_rank: Super Contributor
timestamp: December 20, 2021, 10:33:16 pm
content: It sounds like a tapped inductor. It's also possible that it has 3 pins but only two are actual connections with the third as a mechanical support.

author: Gyro
author_rank: Super Contributor
timestamp: December 20, 2021, 10:36:55 pm
content: It could well be acting as a step-up autotransformer to increase the voltage drive to the piezo. I can't think of any other reasons for having an inductor in a battery operated smoke alarm.Edit: Oops, as langwadt's link.

author: Eamonn58
author_rank: Newbie
timestamp: December 21, 2021, 03:50:26 pm
content: Thanks.Im not sure it makes a difference but it wasnytfrom a smoke alarm but a personal alarm. I want to incorporate it into a car alarm I am making.

author: Gyro
author_rank: Super Contributor
timestamp: December 21, 2021, 03:57:19 pm
content: Ah, I must have imagined that bit (probably thinking loud alarms!). No, no difference, it should make it easier to reverse engineer.

author: Eamonn58
author_rank: Newbie
timestamp: December 21, 2021, 04:00:41 pm
content: Thanks. That looks exactly what it is and it suggests where to get them.Cheers.