hybridfree/eevblog-posts huggingface dataset:
Help understanding SMD identification. - Page 1
Forum section: electronics / beginners

author: OP
author_rank: Newbie
timestamp: January 18, 2015, 08:00:40 am
content: I've searched for a while and haven't been able to find a from the grounds up tutorial on chip identification.The closest thing I've found so far is the SMD codebook, which is completely useless unless you already know the basics of chip identification. For instance, on their introduction page (http://www.marsport.org.uk/smd/codeintro.htm):"To identify a particular SMD device, first identify the package style and note the ID code printed on the device. Now look up the code in the alphanumeric listing which forms the main part of this book by clicking on the first character shown in the left-hand frame."To a beginner like myself, those directions don't make sense at all, and it's just stupidly frustrating:Package style? Looking into package styles, I find the keywords: flat chips, SOT chips, DIP, etc. What type of keyword am I looking for exactly?ID code? Which part of the chip number is the ID code?! For instance, I have a chip "FT9819 G1410 4361I". Is the ID code F, 9, 98 FT, G, G1, 4, 43?! I've looked up entries for all of those, and I do not see the chip listed at all.Can someone please go over a step by step example, or point me towards a better resource?

author: FreddyVictor
author_rank: Regular Contributor
timestamp: January 18, 2015, 01:38:52 pm
content: ok, not really sure if you are simply designing a circuit using smd parts, or if you are trying to determine the exact parts used on an existing board.If it's the latter, then it's really not straightforward.A quick starter on smd parts (sorry, couldn't find your part FT9819) :as an example, anATmega328Pis the general part no, however, this is available in several packages:ATMEGA328P-PU is DIL (Dual inline 0.1")ATMEGA328P-AU is smd type TQFP-32 (32 is no of pins)etcoften, the last additional chars determine the packagesmaller parts obviously won't have this or even their part no printed on themthe list of packages is quite extensive and constantly growing.onsemihave a pdf (link has been removed from their site) with most of the std ones namedcommon ones are SOT-23 (often used for transistors/diodes/voltage regulators) and SOT23-5 (often for v-regs) and bigger ones SO-8, SO-16, SO-20 etcbe aware that there are often std & wide versions of some of the SO** chips so it pays to check the datasheet of the part in question

author: Richard Crowley
author_rank: Super Contributor
timestamp: January 18, 2015, 01:59:13 pm
content: Those codes are for the really tiny packages where there isn't enough space to even print the whole part number.You seem to be describing a chip with full numbering and marking.Deciphering a chip identity involves both separating the part number from all the other nomenclature, as well as identifying the package and taking major clues from the larger context: What kind of gadget is it? What other chips are around it? And connected to it? What signals attach to the board? What kind of input, output, transducers, etc. are associated? Photos are invaluable if asking for assistance.
Help understanding this circuit - Page 1
Forum section: electronics / beginners

author: vmallet
author_rank: Regular Contributor
timestamp: August 17, 2020, 09:45:29 pm
content: I am looking at the oscillator module of an analog synth and I am trying to understand this stage of the circuit. I drew the schematic myself so it might be wrong (hopefully not!)My current understanding:The input comes from the output of the previous stage; goes through a jumper JP1 to select the amplification ratio of U1 (-1/10x, -1/5x, -1x); goes through U2 to be amplified again (at ~ -2x); then goes through the magic of Q1/Q2.We have VCC = +12V, VEE = -12VQuestions:1) Why would R1 be in this picture? If the jumper is in the first position surely the amplification difference between 10/100 and 10/102 has to be negligible (and quite within the tolerance of R2 at 5% anyways).2) Why go through two amplification stages? Could we have used R4 = 20K and achieved the same thing with just U1 (other than being 180 degrees out of phase)?3) How does the Q1/Q2 combo work? I don't think I have seen the collector of an NPN transistor tied to -12V before. I checked the datasheet and the board a few times to make sure I didn't draw that wrong. A bit confused hereThanks!

author: bob91343
author_rank: Super Contributor
timestamp: August 17, 2020, 09:57:12 pm
content: Looks like a mistake, the two transistors need the other polarity to function. It's just a bipolar emitter follower.The two stages provide a little more bandwidth and, as you say, inversion. The trim resistor is to set the gain very precisely.

author: vmallet
author_rank: Regular Contributor
timestamp: August 17, 2020, 10:25:18 pm
content: Quote from: bob91343 on August 17, 2020, 09:57:12 pmI needed to post this to finally find my first mistake (I inverted emitters and collectors.) Here's the new version with Q1 and Q2 fixed:[ Specified attachment is not available ]
Help understanding this EMC circuit - Page 1
Forum section: electronics / beginners

author: desertgreg
author_rank: Contributor
timestamp: August 30, 2019, 03:56:14 am
content: Can someone help me understand the recommended EMC circuit in this datasheet:https://www.cui.com/product/resource/v78w-500.pdfIts at the bottom of page 4, I don't recognize the big 'Z' symbol. Also attached. Thank you for any help!

author: fourfathom
author_rank: Super Contributor
timestamp: August 30, 2019, 04:58:28 am
content: That "Z" just indicates that the two inductors share a common core -- otherwise called a "common mode choke". It's another way of drawing a transformer, when the windings are far apart on the schematic.
Help using a DAC as a current sink - Page 1
Forum section: electronics / beginners

author: ifrythings
author_rank: Contributor
timestamp: October 29, 2023, 05:30:12 am
content: I’m not sure what exactly the circuit I want is called or even if I have the right circuit for my project.A little info about my project, I did a steering wheel swap to a newer steering wheel for my truck, the old steering wheel uses resistive buttons and the new one is CAN bus data. I have the CAN bus part figured out and my idea was to use a DAC to replace the resistive buttons, first problem is the DAC can’t sink up to 16mA, second I tried was using an opamp but the few I had couldn’t sink that current either.Found an app note from TI about a programmable low side current source, that appeared to be close to what I needed but I couldn’t get it to work in the range I needed. So I came up with this circuit, it looks like it will work in the basic simulator, I’m not sure if there’s a better circuit out there or if this one will work what else I may need to keep it stable. I’m not well versed with opamp issues and compensation to prevent any instabilities if needed.Any suggestions and input is welcomed.Hopefully the pictures show up.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 29, 2023, 05:23:34 pm
content: Its the volts that matter here.Controlling the voltage at the PCM node can be done with a voltage output ADC and a buffer.The buffer can be a single supply opamp who's output will swing to near ground at the max current. eg an OPA310.The TI circuit cannot pull its drain down to ground and that will put it out of range. You can make a current sink to suit your requirements (with a negative supply) but it's probably not unecessary. If you want to go the switch route replace each switch with a cheap mosfet eg 2N7002 (dirt cheap). With the resistors <$1!

author: ifrythings
author_rank: Contributor
timestamp: October 30, 2023, 04:16:46 am
content: I tried using a TS27L4CPT quad op-amp but it can’t sink enough current, I will get some OPA4310 on order and try those out as they definitely have a higher source/sink current.I thought about using individual resistors and logic level FETs but I have 22 buttons to do and it’s a lot easier if I need to tweak the circuit in software then changing resistor values.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 30, 2023, 03:59:22 pm
content: If you have a lot of keys its worth thinking about a matrix scanner ic, eg TCA8418. @$2
Help using NPN's as switches. - Page 1
Forum section: electronics / beginners

author: XOIIO
author_rank: Super Contributor
timestamp: March 07, 2014, 09:07:54 am
content: Alright, so I have finally decided to start mucking about with transistors, probably something that people learn at the start but I just never bothered to.Anyways, I am just using it as a simple switch to turn on an LED using a lower voltage source in something I want to change the backlight in. It's backlight is a small SMD one that runs at 1.8 volts, I'm going to use a 3mm one and feed it directly from the batteries (max 3 volts).On the breadboard I was messing around, through trial and error (and realizing I need a current limiting resistor for the thing to work), got it to switch, no problem, powering an LED from 3 volts, however, depending on the voltage I give it and what voltage I use to switch it, it doesn't work very well. I used a battery pack with 3.8 volts and it worked fine, but if I lowered the power I feed to the LED to 2.8 volts it dims drastically. I tried to switch it with a AA battery feeding the LED 3v, and it was extremely dim. What is the cause of this? I imagine it is maybe due to the current limiting resistor? How do I figure out what value it would need to be? Since this thing is running off two AAA's, I'd like a solution (if possible) that just gives the LED full power when triggered with the 1,8 volts or so, since when the batteries dropped to 2..5v or so the backlight would be nonexistent.

author: mariush
author_rank: Super Contributor
timestamp: March 07, 2014, 09:18:20 am
content: See this video which explains how npn transistors work and what those specs in datasheet meen and how to select the resistor:You probably chose a high value resistor which limited the current going from collector to emitter severely.

author: Psi
author_rank: Super Contributor
timestamp: March 07, 2014, 09:40:11 am
content: LEDs have a voltage rating, for red leds its around 2VTransistors, even when switched hard on, have a voltage across them. Usually 0.9V max.So to run a 2V led using a transistor you need minimum 2V + 0.9V = 2.9Vand that isnt taking into account the need to regulate the current with a resistor.In order to do current regulation the resistor needs some voltage across it. For a typical 20mA led you want at least 1 volt across the resistor. Anything less than that and you run into problems because the change in led voltage (due to led temperature) causes the current to increase a lot. So your led gets hot and that causes it to draw more current which causes it to get hotter etc..So.. to run a typical 20mA red 2v led using a transistor the minimum voltage is 2V + 0.9V + 1V = 3.9VYou can run it from less but you need to under-rate the current/brightness to counter the fact that temperature will increase current after switchon.

author: KJDS
author_rank: Super Contributor
timestamp: March 07, 2014, 11:19:48 am
content: Quote from: Psi on March 07, 2014, 09:40:11 amA typically figure would usually be about 200mV for a regular npn or pnp switching transistor.
help wanted-square wave generator - Page 1
Forum section: electronics / beginners

author: Raj
author_rank: Frequent Contributor
timestamp: March 18, 2019, 02:44:51 pm
content: I've been wanting to make a tweezers sized instrument, that generates square wave with zero offset and 30v peak to peak.and the output has limited current. I am currently using the only method I know, which is using an 'H' bridge a boost converter to get 15v along with attiny13 micro controller and a linear regulator to limit current. But it's too big. Suggest something please.

author: AndyC_772
author_rank: Super Contributor
timestamp: March 18, 2019, 02:51:44 pm
content: Can you post a picture of what you already have?Is it already constructed using surface mount components on a PCB?

author: Raj
author_rank: Frequent Contributor
timestamp: March 18, 2019, 03:23:42 pm
content: The linear regulator limits current to 10-20mA according to setting (potentiometer).H-bridge is basically 4 large mosfets. The circuit fits in a box of size 5x5x2cm.I want to make it as small as 4x2x0.5cm or smaller. I think, I can employ analogue circuitry to achieve it. I can use single nand chip to act as both sq wave generator and 'h' bridge but how will I limit output current? 2 Mosfet based current limiter I guess?
Help - What info do I need for this calculation? - Page 1
Forum section: electronics / beginners

author: QuickWittedSlowpoke
author_rank: Newbie
timestamp: March 16, 2018, 06:10:50 pm
content: This is probably a stupid question, but its Friday and my brain hurts.I've been tasked to find out the min and max load requirements for a Pickering reed relay (119 series) and I easily found the datasheet. But I feel like I'm missing some information to answer this question. This is my first "real" engineering job out of college and I graduated in 2015. I'm probably a little rusty on some calculations but I feel like I need more than just the specs from the datasheet...Thank you for reading this!

author: Audioguru
author_rank: Super Contributor
timestamp: March 16, 2018, 06:57:27 pm
content: You forgot to provider a link to the datasheet so maybe nobody will help you.

author: Rog520
author_rank: Regular Contributor
timestamp: March 17, 2018, 12:17:03 am
content: Found the data sheet. I'm not sure what you mean by min and max load requirements, though. Do you mean what size of load is it capable of switching?

author: Zero999
author_rank: Super Contributor
timestamp: March 17, 2018, 12:20:29 am
content: Perhaps posting the data sheet might yield a more helpful response.
Help with 12v 4pin PWM fan - Page 1
Forum section: electronics / beginners

author: happirt
author_rank: Newbie
timestamp: August 22, 2018, 10:25:47 am
content: I am trying to setup a 12v 4pin fan with a potentiometer to regulate the speed. This is not for a PC so I don't have a motherboard, instead just a 12v battery and a NE555 timer based PWM controller.My problem is when the green colored ground connection from PWM controller OUT to common ground is connected the PWM is sending a constant 12v not pulsing as it should. What is wrong here?

author: PTR_1275
author_rank: Frequent Contributor
timestamp: August 22, 2018, 10:28:56 am
content: Is that PWM module switching ground instead of switching positive? Any data sheets on that module?

author: happirt
author_rank: Newbie
timestamp: August 22, 2018, 10:38:52 am
content: unfortunately no diagram, but YES it sounds like it is switching positive instead of ground, what can I do??

author: happirt
author_rank: Newbie
timestamp: August 22, 2018, 10:44:26 am
content: will this switch ground or positive?https://diyodemag.com/_images/5a8bb4a6c672e0a73df42bcf

author: PTR_1275
author_rank: Frequent Contributor
timestamp: August 22, 2018, 11:13:44 am
content: That’s switching negative.

author: happirt
author_rank: Newbie
timestamp: August 22, 2018, 11:22:27 am
content: Is there a way to use it with my application?
Help with a build - Page 1
Forum section: electronics / beginners

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: October 20, 2012, 10:17:45 am
content: I am really trying to build my first circuit here and what to get some help and thoughts with this idea...Here is my schematic so far... I am not sure on where I am going to install the input leads for the volt meter but would like so input... I can't do any auotcad or google sketch to show how it's going to look so far..Here is the videoHere is some of the part listDigital Voltmeter modsimple sche of logic probe (duel input led and 2 resitors)project boxRocker switch (spdt or dpdt )I already have plenty of wire and connectorsresettable fuse

author: Jonny
author_rank: Regular Contributor
timestamp: October 25, 2012, 09:55:50 am
content: Connect it to the probe..... ?
Help with a circuit to turn off a load when battery voltage is below a threshold - Page 1
Forum section: electronics / beginners

author: BlackICE
author_rank: Regular Contributor
timestamp: December 09, 2020, 09:28:57 am
content: I would like to have a simply circuit to turn off a load until the device is power cycled when a battery voltage is below a threshold value. This is to protect the battery from being deeply discharged. Ideally when the power is turned on just from connecting a battery to the circuit and stay on until either the power is removed or the battery voltage is too low. I would like to avoid using a relay and to use a mosfet switch instead to save power. The total power consumed will be between 0.5 to 1 amp. with a nominal 12V supply (really anywhere from 9 > V > 17. If it would simplify the circuit I'm open to adding switch to turn it on. I have ideas of how to do it with a micro controller or switch and comparator, but are there any simpler ways using only passive components other than the mosfet switch?Any ideas would be appreciated.

author: nfmax
author_rank: Super Contributor
timestamp: December 09, 2020, 09:49:43 am
content: Take a look athttps://www.eevblog.com/forum/projects/battery-undervoltage-lockout/msg1060148/#msg1060148which is a circuit I designed for exactly this purpose

author: BlackICE
author_rank: Regular Contributor
timestamp: December 10, 2020, 07:56:22 am
content: Thanks I read that link and decided for now to buy some devices mentioned their to see what results I get.
Help with a college project - Page 1
Forum section: electronics / beginners

author: teslaboom
author_rank: Newbie
timestamp: November 26, 2014, 03:38:28 am
content: Hi!I made an electro-magnet lamp with a friend for a college project, and we upload the video to youtube.We need as many likes and views as possible.If you can share and of course give us your like in the video we will appreciate it.feel free to gives feed back in this postthank you in advance friends.!!
Help with a connector - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: November 14, 2021, 04:44:03 pm
content: Hi, I have an epaper display and I want to play with it but I'd like to know what connector is this:And if I can crimp the cables with the same crimping tool I use for JST-XH headers, which is anEngineering PA-09thanks!

author: ledtester
author_rank: Super Contributor
timestamp: November 14, 2021, 06:09:29 pm
content: Is the pitch 2mm?This aliexpress listing has a similar looking photo and calls them "JST PH2.0" headers:https://www.aliexpress.com/item/1005003538942517.htmlThe official JST catalog for wire-to-board products may be found here:https://www.jst.com/products/category/crimp-style-connectors-wire-to-board-type/and the PH catalog page:https://www.jst.com/products/crimp-style-connectors-wire-to-board-type/ph-connector/

author: Moriambar
author_rank: Unknown
timestamp: November 14, 2021, 07:01:47 pm
content: Quote from: ledtester on November 14, 2021, 06:09:29 pmThanks that could be it, I'll measure the pitch later but I'm fairly sure you got it!
help with a homade  hydrophone - Page 1
Forum section: electronics / beginners

author: Edwin the inductor
author_rank: Newbie
timestamp: July 01, 2020, 02:08:42 pm
content: Hello I wont to build a home made hydrophone and I wonder where I can find the hydrophone I'm not luking for sommagical thing just a good one.grateful for help.

author: RJSV
author_rank: Super Contributor
timestamp: July 09, 2020, 12:45:09 am
content: Assuming you want parts,. Maybe try using the following:First try won't cost any substantial money. Get a plastic bowl and you will be gluing a sheet of clear and thick flexible plastic. The idea will be to also arrange asmall one inch speaker on a post. Then you will eitherglue directly, or more likely find a tiny piece of wood orplastic. The result is a microphone that should be immersable but only just below surface.I use D-6000 or E-6000 not sure. The output will bequite low so prepare to turn op your audio.
Help with a metal detector circuit - Page 1
Forum section: electronics / beginners

author: showlyshah
author_rank: Newbie
timestamp: November 02, 2019, 09:14:32 pm
content: hello alli want a help regarding a project.https://blog.podkalicki.com/attiny13-pi-metal-detector/i build this one using attiny 85 . and it works good. but the problem is since it uses only 5 volts to power the coil .. its less sensitive to smaller objects. like a gold ring. for a gold ring the distance is about 4-5 cm at maximum sensitivity. but for gold bangle ..its about 10 cm.. for larger objects like a metal spanner.. it works about 15 cm.i want the circuit to be more sensitive.. like 30 cm for a gold ring. ( actually my friend lost his pretty expensive gold wedding ring on some shrubbery area and i am trying to help him find ).so my idea is to run the coil on 12-18 v ( 2*9v pp3 battery ) to get more power. but as you can see.. the sense wire is hooked directly to i/o port of attiny. and when i measured the voltage through the sense wire .. ita almost as vcc voltage.. so if i run the coil on 12-18 volts.. it will feed back that higher voltage to the attiny and will fry the chip.can anyone please help me to modify the same circuit to power the coil section at Higher voltage ? and still retain the original working of the circuit?i know there are so many pi based circuits.. but this one is amazingly simple.. thats why i choose it.please help me as quickly as possible.thank you all

author: StillTrying
author_rank: Super Contributor
timestamp: November 03, 2019, 02:41:50 pm
content: "so if i run the coil on 12-18 volts.. it will feed back that higher voltage to the attiny and will fry the chip."All you've got to do to stop the 12V getting to the attiny sense input is to move the top of D2 to the attiny's VCC, in theory, and maybe increase the 10k value of R6.

author: pwlps
author_rank: Frequent Contributor
timestamp: November 05, 2019, 04:43:57 pm
content: The "pulse induction" technique used here is based on the change of the decay time when the quality factor is affected by nearby metallic objects. But the quality factor does not depend on the voltage so I don't understand well why you expect to get more sensitivity with higher voltage. If this is merely to reduce the noise in the measured voltage I would first try averaging many measurements. Actually I don't see any averaging in the code ("measure_decay" function) so there is maybe quite a big margin left to improve things on the software side before changing anything in the hardware.EditThe sensitivity will be a rapidly decaying function of the ratio diameter/distance (asymptotically something like a 3rd power) therefore to increase the sensivity to larger distances you should rather use a larger coil. The original 5cm-diameter coil will have a vanishingly decreasing sensivity at 30cm or so, on the other hand a 30cm coil will have a smaller overall sensivity but it will decrease much less around 30cm.Edit 2Apparently the calibration code does not take into account the signal/noise ratio. An optimal threshold calibration should choose the optimal pulse repetition rate in function of the measured S/N.
Help with a motor - Page 1
Forum section: electronics / beginners

author: houdini
author_rank: Regular Contributor
timestamp: June 02, 2012, 01:09:45 am
content: Hi so i am fairly new to electronics and i was taking apart a l&w resonance stiffness tester and found a huge motor and i was wondering if it would be posible to drive it from an arduino.It is a 5 phase stepper and on the original board there are 5 chips attached to heat sinks marked irft 003 ior9450d3 marked p9706sd dm74lsoon.3 marked p9652sl dm7406n3 marked m9642ak lm319nso if any one could help that would be great thanks.

author: hlavac
author_rank: Frequent Contributor
timestamp: June 02, 2012, 02:04:11 am
content: 140W motor with Arduino? Not directly. You would need some massive MOSFETs, and a beefy 70V 140W power supply. MOSFETs are not so easy to drive either, requiring ~10V gate voltage... and probably also isolation to protect your arduino from the electromagnetic mayhem the motor will causeAssuming the motor is 5 phase unipolar stepper motor, you need a driver board with 5 channels of: logic signal input from arduino -> optoisolator -> MOSFET driver -> MOSFET to switch the 70V onto each phase of the motor. Maybe some safety logic so you don't turn on more than one phase at the same time and blow up your power supply. Maybe also some current limiting for safety.

author: amyk
author_rank: Super Contributor
timestamp: June 02, 2012, 11:44:47 am
content: The first picture posted is the driver board. It should have everything you need besides the power supply.IRFT003 datasheet --- 60V 6A H bridge --- looks like an old part:http://www.datasheet.co.kr/download.php?id=535900Given that the H bridges are only rated for 60V the motor is probably being driven at a lower voltage than its rating.I see an 'OG' peeking out from underneath the sticker on the DIP40, is that a Zilog Z80? If there are ROMs on the rest of the what you pulled it from, they might already have the firmware needed to drive the motor. Do a little investigation on the data connector and the drive board, see how everything is connected. You should be able to interface the Arduino to the MCU on there and offload the motor driving to it.

author: houdini
author_rank: Regular Contributor
timestamp: June 02, 2012, 11:36:13 pm
content: there are lots of roms there is another board that has like 50 ic on it but i dont know if it still works

author: Psi
author_rank: Super Contributor
timestamp: June 03, 2012, 05:25:38 am
content: Quote from: hlavac on June 02, 2012, 02:04:11 amcan use logic level mosfets, then ya only need ~3V.So a 5V micro will work fine with a transistor to "up" the available current for fast switchover.They don't need to be massive either.Lets say you use a mosfet with 50mR on resistance.2A for the motor across 50mR = (2^2)*0.05 = 0.2WAnd obviously more during switchover but its not exactly massive.TO-220 or dpak will do that no probs.However i don't know why the motor says 0.9R.Maybe that's DC short circuit resistance.EDIT (yep, it is, winding resistance with zero magnetic coupling)
HELP with a project! - Page 1
Forum section: electronics / beginners

author: christos
author_rank: Regular Contributor
timestamp: July 14, 2014, 09:09:12 pm
content: hello..i need some help with a project im doing..i need something like wirless,,when the transmitter gets close like 40cm-100cm the receiver will trigger a LED..if i manage to build this thing ,i will need 5 of these,so i need it be able to set 5 channels, so lets say that TX1 will not trigger RX2 or any other channel except channel RX1..i was thinking for InfraRed led and receivers but i cant get the InfraRed(IR) receivers to work in multiple signals..i want to build 5 of these that i can choose what frequency each will use(like have a switch in each of them with 5 diferents operation frequencys )what can i do??do i need to use a microcontroller?if i can use just normal materials like resistors,transistors and other exept Microcontrollers would it be cheaper or expensive?what can i do???

author: Paul Price
author_rank: Super Contributor
timestamp: July 14, 2014, 11:21:30 pm
content: if you use a MCU within each receiver to decode the infrared (TV/VCR etc) remote-control type signals from each of the transmitters, then each transmitter can have it's own signature code that could be identified by any of your five receivers.The idea to get this to work with other transmitters in close proximity is to only allow the transmitters to transmit short code bursts of their id code with significantly longer quiet times between transmitted code burst intervals, thus allowing other transmitters an opportunity to send their code to each receiver without any one transmitter jamming a transmission from another.If the transmitters themselves have infrared receiver circuits that serve only to detect if another infrared transmissions is already in progress, then a transmitter could politely wait until another has finished its id code transmission before sending its own id code.Your transmitter MCU code would benefit from some sort of bus-arbitration scheme to resolve a possibility that many transmitters are competing for the attention of a single nearby receiver. For example, there could be a priority set for the order of transmissions, thus allowing each to transmit only when it has allowed higher priority transmitters to finish their id transmission when it finds itself engaged a crowded situation.

author: christos
author_rank: Regular Contributor
timestamp: July 16, 2014, 08:35:45 pm
content: i found this onehttp://www.electronicshub.org/5-channel-ir-remote-control-system-using-microcontroller/would this do my job?if yes,,how can i set tha receiver to only recognize the channel i selected on the transmitter?it uses a Darlington array IC ,,if i replace it with a 5 channel switch or use a switch after the darlington ic with all the output pins from the switch connected to a motor or a led,would it work?i made a diagram on how i want it (its verry simillar like the link i posted)http://postimg.org/image/yamwgpkhp/
help with a random sensor board how is it working? see pictures - Page 1
Forum section: electronics / beginners

author: apbosh1
author_rank: Contributor
timestamp: September 04, 2013, 09:54:45 pm
content: Hi,i'm told this board is/was used in a sliding window arrangement a bit like drive through windows auto shut/open.I've been trying to figure out the exact workings just for education for all my efforts i cant give a confident answer on alot of things, anyway a brief of my observations:one chip is a n555n and the other is an op amp as shown in picture i looked at spec sheet andthink i made a little sense of its characteristics.2 dark coloured leds ? what exactly is their job? one is exposed and the other has a bit of rubber tube covering the sides also a green led which i think is just a status light OR is it influencing one of the photo diodes (its not a modulated supply to this) i've taken one of these "dark" leds out from another identical board and they produce a voltage in light so Photo diode?? or is one infer red or both?? the output pin 3 of 555 chip delivers a 1.8khz sq wave signal but the duty cycle is very high i make it only 10u seconds off time and that feeds into the rubber coated led so is this the infered signal out and when the window opens a reflector mirrors the ir back to the non covered led/photodiode and the opamp takes it to the motor control etc i've got no idea really . Why the leds? and with 10u secs off time another control board (somewhere in the auto window design) must be able to operate at 100khz in order to detect that. i suspect i've gone way off course but tell me what you think and i'll supply whatever info i can in addition. sorry the picture looks a bit big on my screen hope you can zoom out a bit if not i'll do again.Andy

author: David_AVD
author_rank: Super Contributor
timestamp: September 04, 2013, 10:13:37 pm
content: Looks like the shrouded LED is an IR emitter (modulated by the 555) and the other dark one is a detector used with the opamp.As you say the green LED is probably a status indicator.The circuit looks very simple to draw out.
Help with a UPS fault - Page 1
Forum section: electronics / beginners

author: openthomas
author_rank: Contributor
timestamp: October 22, 2012, 10:05:13 pm
content: Hi all,My APC UPS's are coming up with building wiring fault. According to the documentation there are 3 possible causes.1 overloaded neutral wire2 reversed polarity3 missing ground wireI am sure its not the polarity, used a socket tester. How can I measure the ground connectivity and how can I check for an overloaded neutral wire ?

author: BigBrother
author_rank: Regular Contributor
timestamp: October 22, 2012, 10:10:24 pm
content: I have two APC Back-UPS XS 1500. They complain with this same thing if I use them on a surge protector or power strip.

author: openthomas
author_rank: Contributor
timestamp: October 22, 2012, 10:28:42 pm
content: In this case its plugged into the wall socket. I am guessing overloaded neutral. Interestingly when I plug this UPS in, apc smartups 1400, my 3m 724 sends out an alarm saying my dissipative mat which is being monitored is not functioning. That device uses two ground connections. One is sourced from a radiator and the other from the wall socket. When I plug this UPS into any socket in the building, the alarm goes off on the ESD workstation monitor. The monitor compares the two grounds. Puzzle....

author: openthomas
author_rank: Contributor
timestamp: October 22, 2012, 10:44:07 pm
content: I have measured the ground to neutral. With the UPS plugged in its 20V. Without it, 5.18V.So ......what does that mean ? Its overloaded and the UPS makes it worse but does that mean the UPS is faulty ?

author: openthomas
author_rank: Contributor
timestamp: October 22, 2012, 10:47:30 pm
content: With a different UPS ground to neutral goes to 17V but in this case the workstation monitor does not sound. Perhaps because it uses a 16V signal to test the mat ?

author: openthomas
author_rank: Contributor
timestamp: October 22, 2012, 10:48:06 pm
content: Will 20V on the neutral damage my equipment ?
Help with Agilent MSOX SPI triggering/decoding - Page 1
Forum section: electronics / beginners

author: andrewwong2000
author_rank: Contributor
timestamp: August 14, 2014, 04:26:39 pm
content: Starting to really come to grips with the digital decoding capabilities of an MSOX, and I can't seem to figure this one out.The problem is trying to use segmented memory to identify each 8 byte conversation between Master and Slave.My test setup with an AVR programmer sending $AC $53 (Programming Enable) and $30 $00 (Read Signature Bytes) to an Atmega328p. There are 3 bytes to be read back (giving 0x1E950F).Screen3.png shows the whole conversation. I am trying to get the segmentation capture to give me each 4 word conversation per segment.After much experimentation, I found the most reliable trigger is Nth Edge (2nd rising clock edge) of CLK with an idle of 700us between clock words. The best I can do is capture bytes 1 (acknowledge programming mode), 2 (0x1E) and 4 (0x0F). It seems to always miss the 0x95.. and only give me back 3 segments if I use segmentation.Using the SPI trigger with MOSI and all bits don't care gives me the first command AC53.. but doesn't trigger again for subsequent words sent by the Master (eg. segmented memory only recognises 1 segment).My trigger holdoff is set to minimum 40ns (and I've tried any values in between).Appreciate if anyone can help me figure out what I'm missing here. The signals are stable and repeatable,and I'd like to get this working before I try to:a. Get the decode lister to not group all the data into a single lineb. Decode something more significant like setting fuses, programming memory via SPI etc.
Help with an OK Industries iron wiring please - Page 1
Forum section: electronics / beginners

author: shanezampire
author_rank: Contributor
timestamp: July 01, 2019, 08:52:51 pm
content: Long story short is I picked up an OK Industries SA-1001 a while back but it did not come with a hand piece/iron. Its been sitting on a shelf forever. IF you can find an iron for it it, it cost more than just buying something newer.It has a 6 pin din on it so I bought a HAKKO FX-888 FX-888D FX-8801 handle which has the same 6 pin lay out hoping with would work. Well it wont even plug in to the female part of the station. Size difference. So I can just order a new female din thingie for the HAKKO, solder it in on the station, and it will plug in.But before I go ordering more stuff and soldering and all that, I wanted to make sure the station even works. But I have no idea what/which wire are sensors and heaters and all that. I did manage to jump a wire or two and heat the iron up but I aint sure the temperature adjustment is working. I know once I seen the heating LED light come on but I couldn't figure out what I done to replicate it again.Below is a few pictures of the wires if anyone can figure it out.There are 6 wires going to the din plugThe green is a ground to din plugA red and grey come in from behind transformer straight to din plugA Yellow, Blue, and Black from the temp control board6 wires total ..the grey is the center wireGreen 2 o'clockBlue 4 o'clockRed 6 o'clockYellow 8 o'clockBlack 10 o'clock

author: shanezampire
author_rank: Contributor
timestamp: July 01, 2019, 10:00:04 pm
content: Back of the transformer. Looks like about 16v on 2 wires and 33v on second set
Help with Arduino based project - Page 1
Forum section: electronics / beginners

author: slambo511
author_rank: Newbie
timestamp: August 13, 2017, 08:56:26 am
content: Hello, this is my first post here and I am not really an electronics guy but a programmer, so please bear with me.So I have a project which I use to teach students a number of concepts in programming, primarily binary, hexadecimal and low-level programming. It works by allowing the students to wire up a front panel with 10 inputs, each representing 1, 2, 4, 8, 16, 32, 64, 128, 256 and 512 respectively. As each connection is made the OLED display on the top outputs either the total in binary, hex and decimal or a simple instruction set.I am using the I2C bus for the OLED.My problem arises from my need for 10 inputs (one for each connector) and the Arduino not having that many to work with. I have looked at using ICs and the I2C bus, ICs and the SPI bus, relay banks, analog input using resistors to allow multiple switches on one input and a few other things I have forgottenSo my question, after all that, is this - what is the best approach and can you please elaborate.Thanks in advance.

author: LabRat
author_rank: Contributor
timestamp: August 13, 2017, 09:08:10 am
content: I have had good results with the MCP23017 port expander and there are arduino libraries available. 5v compatible, cheap and come in DIP package. Would give more than enough extra I/Os for your needs.Uses I2C but as long as the address is different than the OLED then there shouldn't be a problem sharing the same bus.

author: Brumby
author_rank: Unknown
timestamp: August 13, 2017, 01:21:25 pm
content: Do you have some analog inputs available?If so, I might suggest you think about setting up your switches to some R-2R networks and use the output from them as input to an analog read. All you have to do is set the range of analog levels for each binary value.For example, if you use 3 switches per analogue pin, there will be 8 binary values which you would need to extract from the analog range of 0 to 1024. This would give you a band of analog values of around +/- 64 from the mathematical expectation, which would allow high confidence in an accurate detection. Use some 1% resistors and it shouldn't be too far off. Experimentation can confirm before committing.With 3 switches per pin, you could do 12 bits through 4 analog pins.If you use 4 switches per pin, the bands become narrower: +/- 32. You could do 12 bits in 3 analog pins, so long as the resistor network had the necessary precision and/or was mapped experimentally..
Help with Art of Electronics Exercise 2.5 - Page 1
Forum section: electronics / beginners

author: michael.hill
author_rank: Unknown
timestamp: April 29, 2015, 06:40:23 pm
content: I just got the 3rd edition a little bit ago and I'm forcing myself to do some of the exercises. Exercise 2.5 basically says you have a +15V regulated supply and to use a voltage divider with the output at the base of a  transistor and use it as a emitter follower such that the output is +5V. The maximum load current should be 25 mA. Then it says to size your resistors such that the output voltage does not drop more than 5% under load.----------------+15V| |R1 > |> ||------|<R2 > |-----------o Vout> > R3 || > > Rload---- | >-- ---- |-- ------This is what I came up with for a basic schematic (sorry for the crudity). I know that Ve has to be 5 volts, so Vb has to be 5.6 V to account for the diode drop. I also know I can get the relationship between R1 and R2 is R2/(R1+R2) = 5.6/15. However, I'm not exactly sure where to go from here. Do I have to make a guess for Beta? Can I say R3 = deltaVe/deltaIe ? Need some help.Thanks,Michael

author: smjcuk
author_rank: Frequent Contributor
timestamp: April 29, 2015, 09:22:50 pm
content: This is how I do it.Start at the load and work backwards. Consider two scenarios:1. no load (Rload = infinity/open circuit ... R3 || infinity)2. under load (Rload = 5v / R3 = 25mA ... R3 || Rload).Ergo you need to consider R3/Rload as a current divider (KCL), then work back through the transistor. Then set the bias point of the transistor to set Ve of the transistor.R3 can be quite small if that's helpful in checking answers.Beta is a shit as it varies a lot between individual transistors and with temperature and operating point so you might want to read ahead a bit to cover designs that aren't as dependent on it as this example. Not sure where it is in 3e but in 2e there is a whole section on why beta is bad.Also, TaOE isn't that well written from a tutorial perspective IMHO (although I only have the 2e as reference). The following is more useful for foundation knowledge (with errata from their web site):http://www.amazon.co.uk/dp/1118217322/Edit: stupid mistake due to too much cider
SOLVED: Help with Art of Electronics exercise: Capacitors - Page 1
Forum section: electronics / beginners

author: SpannersToSparks
author_rank: Regular Contributor
timestamp: June 24, 2017, 08:44:27 pm
content: HiCan anyone help with this exercise in AoE (Third Edition) please? Its page 19-20 of the book (not the student manual).QuoteThe book keeps telling me that maths is out of keeping with The Art Of Electronics, then stumping me with maths questionsThanks for reading,Spanners

author: SpannersToSparks
author_rank: Regular Contributor
timestamp: June 24, 2017, 08:59:57 pm
content: Ack NVM, I figured it out.Substitute I = C(dV/dt) in [dU = VI dt] and then integrate.
Help with attenuator to test vintage preamp - Page 1
Forum section: electronics / beginners

author: akabek
author_rank: Contributor
timestamp: November 16, 2022, 04:39:51 pm
content: I have a vintage Sony TA-2000F preamp that I recently recapped. I was planning to go through the calibration/adjustment procedures but the service manual is using an attenuator in the test equipment setup. The test gear I have on hand is a Rigol DG1022Z waveform generator, Siglent SDS-1104x-E scope and a HP 8903a Audio Analyzer.Attached is a page from the service manual and diagram fig. 3-4 shows the test equipment setup. It says to feed a 1kHz signal to the input jack of the preamp, adjust the attenuator to obtain a 1 ac V at the VTVM, and the oscillator output kept to 0.775v (0db). It also shows a 600ohm resistor before the preamp input.The attenuator needs to have an impedance of 600ohms unbalanced and capable of attenuating signals 60db or more.I have used test equipment for basic testing so if my question is silly I am in the early learning stages. Is there an attenuator feature I can use from my waveform generator to attenuate the signal and obtain the 1 volt signal to the VTVM? Or would I need an external attenuator?

author: srb1954
author_rank: Super Contributor
timestamp: November 16, 2022, 10:37:06 pm
content: Quote from: akabek on November 16, 2022, 04:39:51 pmYou can perform this procedure using the 8903A alone except for doing the PHONO LOW input testing.Select AC Voltmeter mode and set the display to Log mode. Set the output amplitude (AMPTD) to the expected sensitivity figure using the dBV suffix key and set the AMPTD INCR to 0.1dB.Connect the 8903A output direct to the preamp input and the 8903A input direct to the preamp output and slowly adjust the amplitude up or down using the increment arrow keys until you achieve the desired preamp output level i.e. 0dBV = 1V. Press the AMPTD key again and the display will directly display the sensitivity figure, which is just the oscillator output level.Since the 8903A output doesn't adjust low enough to check the PHONO LOW sensitivity you will need to add an external attenuator of 20dB between the 8903A output and the preamp input. Measure using the same procedure as above but mentally subtract 20dB from all readings.
Help with basic DC circuit accepting charging input - Page 1
Forum section: electronics / beginners

author: Mannixa
author_rank: Newbie
timestamp: December 05, 2017, 08:45:44 am
content: This is a basic wiring I have done for running a 12VDC appliance off my lead battery while simultaneously having an input charging source.https://ibb.co/nxFHvGMy understanding is when the charger is connected the connected appliance (fridge) drawing power will take it from the highest voltage which will always be the charger. So the battery capacity will remain untouched.Or does some of the charger's electricity make it to the batteries terminals topping it up if the fridge is not consuming too much power?Just looking to understand if this kind of wiring setup is done ok & safely. And I'm not sure about electricity & how it works so wanted to ask.

author: Mannixa
author_rank: Newbie
timestamp: December 06, 2017, 07:21:09 am
content: thanks for those with nothing better to do than view & not give an answer. horrible internet pieces of shit

author: Jeroen3
author_rank: Super Contributor
timestamp: December 06, 2017, 07:30:37 am
content: 2017-12-05 T 09:45:44 to 2017-12-06 T 08:21:09.That's only 22 hours 35 minutes 25 seconds.You should reavaluate your comment to expect answers, I guess.

author: woody
author_rank: Frequent Contributor
timestamp: December 06, 2017, 07:56:21 am
content: Quote from: Mannixa on December 05, 2017, 08:45:44 amYou understand correctly. Think watertank for battery, filling hose for solar charger and tank tap for appliance. As long as the filling hose fills at the same rate as the tap is using water, nothing changes. If the filling hose delivers less water the level in the tank goes down and if the filling hose delivers more water than the tap uses the tank level goes up.QuoteI am not qualified to tell you if this setup is ok and safe. maybe someone else is.

author: woody
author_rank: Frequent Contributor
timestamp: December 06, 2017, 08:06:41 am
content: Quote from: Mannixa on December 06, 2017, 07:21:09 amMy apologies. But you must understand that we had our annual Sinterklaas party yesterday. Lots of kadootjes, gedichten, speculaas, pepernoten, chocoladeletters, children in a sugar coma, drinks, heavy discussions around Zwarte Piet, more drinks, fights and what not. So I first had to sleep this off, have my morning coffees and fire up the PC before I could answer your urgent question.

author: mikerj
author_rank: Super Contributor
timestamp: December 06, 2017, 09:01:14 am
content: Quote from: Mannixa on December 06, 2017, 07:21:09 amWow. Entitled millennial?
help with building a transformer inverter - Page 1
Forum section: electronics / beginners

author: kosacid
author_rank: Contributor
timestamp: November 11, 2017, 10:58:22 pm
content: ok i got hold of a old transformer and im using 2 irf740 and a arduino for switching using a centre tap, it is a variable frequency pwmthat is all working fine the problem i have is it puts out the right ac voltage but no load so i ended up pulling the transformer apartfound out it only had 10 turns and 40, i have looked over the net and i cant work it out how to calculate the centre tap so can someone show methis is what i havethe centre tap was 1mm copper wirethe core is 20mm x 20mm depth 30mmi didn't unwind the primary but it is 68ohm 45.0mh 0.25mm copper wirethe iron core is 65mm x 55mmso can some one tell me how much winds it needs and show me how to do it, it will be running of 12vand what difference will it make if i wind it with say 0.5mm copper wire with a centre tap