hybridfree/eevblog-posts huggingface dataset:
How to check comparator - Page 1
Forum section: electronics / beginners

author: giosif
author_rank: Frequent Contributor
timestamp: June 30, 2018, 10:50:39 am
content: Hi,I am trying to check if an LM393 dual comparator IC is healthy and I wanted to confirm whether the circuit I've been using for testing op-amps located at the link below could be used for comparators as well.https://startingelectronics.org/beginners/circuits/op-amp-oscillator/If I am to judge things from the data sheet of the LM393, it looks like I should be able to use that test circuit but, OTOH, since there seems to be a differentiation between op-amps and comparators, I am not 100% sure.A quick search on the forum didn't reveal a similar topic.Thanks!

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 30, 2018, 12:25:25 pm
content: A lot of comparators can only sink current to GND, and not output a voltage.Therefore you have to modify your circuit a bit.Instead of connecting the led between the output and GND, put it between the positive supply rails and the output.Aditionally, you might want to put another resistor parralel to the led to pull the output closer to the supply rails if the led is off.

author: giosif
author_rank: Frequent Contributor
timestamp: June 30, 2018, 01:00:55 pm
content: That is most interesting and a very subtle difference (to me, anyway).I've modified the circuit and I can see it oscillating now.Thank you for that very useful piece of information!I am suspecting the comparator is sinking current to GND when the inverting input is higher than the non-inverting one, right?
How to check for USB-RS232/TTL chips genuinity? - Page 1
Forum section: electronics / beginners

author: Logan
author_rank: Frequent Contributor
timestamp: October 18, 2022, 03:18:47 pm
content: Hi.With so much fake Chinese clones on market, are there any good/definite way to check FTDI/CP210x chips for genuinity(without damaging them of course)?I've heard the famous FTDI driver identify fake chips on Windows, but with so many years passed, I'm afraid newer fake chips can get around it?Also, that's for FTDI+Windows only. What about other brands/OS?Thanks.

author: MikeK
author_rank: Super Contributor
timestamp: October 18, 2022, 04:02:24 pm
content: Under Windows you can check the serial number in the Device Manager. Fakes are almost always A50285BI or all zeros. Under Linux you can use the lsusb command.

author: Logan
author_rank: Frequent Contributor
timestamp: October 18, 2022, 05:00:16 pm
content: Quote from: MikeK on October 18, 2022, 04:02:24 pmThank you!What about Silicon Labs CP210x series?

author: MikeK
author_rank: Super Contributor
timestamp: October 19, 2022, 03:32:56 pm
content: I don't know about the Silicon Labs stuff. Maybe someone does? At the very least you could compare the chip ID and logo burned into the top compared to an official SL chip. There are probably images of that online.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: October 19, 2022, 11:15:12 pm
content: I'm fairly sure both companies have utilities that let you configure the chip. Maybe they can scan for fakes too.

author: Logan
author_rank: Frequent Contributor
timestamp: October 21, 2022, 12:53:40 pm
content: I just use "lsusb -v" in Linux to check my CP2102, and one of the line shows "iSerial = 0001"... Is that fake?I'm just about to use it on a very expensive device, should I stop?

author: py-bb
author_rank: Regular Contributor
timestamp: October 22, 2022, 12:57:19 am
content: Quote from: Logan on October 18, 2022, 03:18:47 pmI can help here but it's Linux only, and we only did it for a few (so we didn't automate it) but you could build something that could. If you want to inspect thousands just by plugging them in you'll need to develop a test, we got suspicious from appearance and such.I'm new to this forum, if I don't reply, private message me? I'll keep an eye out.
How to check I2C communication - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: March 15, 2019, 08:46:32 pm
content: There are three I2C devices in an equipment and I would like to check if they communicate properly with the main CPU. Does anyone have any idea how to test the communication?

author: sambonator
author_rank: Regular Contributor
timestamp: March 15, 2019, 09:05:03 pm
content: Not sure if anyone can answer that without knowing what test equipment you have, what CPU you're using... but usually there's a command you can issue to see if your CPU sees the device address on the I2C bus.

author: KL27x
author_rank: Super Contributor
timestamp: March 15, 2019, 09:22:37 pm
content: You can find out if they are talking by troubleshooting. See if they are responding to each other. You have to figure out under what circumstances the devices should talk to each other to produce some response, then create that condition and look for the response. You may have to read some datasheets, if the result is not obvious or if you suspect some error.Or you can use a logic analyzer with I2C protocol to monitor the bus and see what communication is occurring by individual address.Depending how much "verification" you need, you can use any logic analyzer or a digital scope to verify that there is at least some communication. But you'll have to work out the addresses and instructions yourself.You should probably have listed what is the problem or suspected problem. Or w/e is your goal.

author: rstofer
author_rank: Super Contributor
timestamp: March 15, 2019, 09:25:03 pm
content: Any logic analyzer will be able to analyze the bus. You will be able to see start condition followed by the address byte/command followed by 1 or more bytes of data followed by the stop condition. That's the easy part.Understanding the data transfer and what it means to the parties will take a lot more time.One thing you might see is a NAK condition where there should be an ACK condition. This is a real clue that the slave device didn't understand or didn't acknowledge what the master device was saying. Or the device being addressed isn't on the bus...But it will take some kind of logic analyzer or a scope that includes decoding.

author: macboy
author_rank: Super Contributor
timestamp: March 15, 2019, 09:46:00 pm
content: "Bus Pirate" can snoop on an I2C bus, and I have used it for a similar purpose.
How to check if a mosfet is dead? - Page 1
Forum section: electronics / beginners

author: sean87
author_rank: Regular Contributor
timestamp: May 05, 2013, 12:37:24 am
content: Hi guys,I am trying to repair my XBOX 360. It turns on for a fraction of second, gives the normal beep but turns of right after.I have already checked for bulged caps, blown stuff and any funny stuff in the PCB but I haven't find any.Now I am checking the mosfets. I came across 4 mosfets of this type:http://www.mouser.com/ds/2/389/CD00240517-60235.pdfST 75N3LLH6 the DPAK version. I have put my multimeter in diode test mode and if I put the multimeter between TAB and pin3 of the mosfet, my multimeter beeps meaning those 2 pins are shorted and I think they shouldn't be shorted!!. Does this mean that the mosfet is dead?There are some big coils on the PCB...can they affect my measurements? should I take out the mosfet and check again? all and all how can I check a typical mosfet like that using only multimeter?Thanks!

author: jmole
author_rank: Regular Contributor
timestamp: May 05, 2013, 12:47:37 am
content: If the channel is active, the D-S connection will be effectively shorted. Measure the voltage across the gate and source, and if the voltage is >~2.5V, then the D-S connection should be very low impedance. Otherwise, the mosfet may be fried.

author: sean87
author_rank: Regular Contributor
timestamp: May 05, 2013, 12:49:56 am
content: Well I did the test when the power was unplugged...then can I be 100% sure that its fried?

author: sean87
author_rank: Regular Contributor
timestamp: May 05, 2013, 12:50:44 am
content: By the way what do you mean by low impedance? acnt get the idea...

author: Skimask
author_rank: Super Contributor
timestamp: May 05, 2013, 12:51:09 am
content: That MOSFET has a "back body diode" on it, meaning that when you're doing a diode check across S & D, it'll effectively be shorted in one direction, not in the other.

author: Skimask
author_rank: Super Contributor
timestamp: May 05, 2013, 12:52:39 am
content: And yes, to test it "right"-er, you'll likely have to pull the MOSFETs out to prevent the meter from reading other components in the same circuit.

author: sean87
author_rank: Regular Contributor
timestamp: May 05, 2013, 12:58:54 am
content: Quote from: Skimask on May 05, 2013, 12:51:09 amOk I will take out one and check later. But for now, no matter which direction I check, the multimeter beeps. so does it mean the diode you talk about is dead?Also!!! there are like 6 of these mosfets on board. 4 of them are beeping constantly. There are 2 other somewhere else on the board. If I check for short they just beep for a fraction of time and then they don't beep. So does it mean they are fine?

author: c4757p
author_rank: Super Contributor
timestamp: May 05, 2013, 01:17:14 am
content: Briefly bridge the gate to the source, then measure. That MOSFET easily has enough gate capacitance to hold a charge and keep it switched on.
How to check if my circuit and component work? - Page 1
Forum section: electronics / beginners

author: ssport
author_rank: Newbie
timestamp: February 26, 2024, 11:23:50 am
content: Hello,I am new one in a electronics and I would like to check does my circuit components work. I assume that optoculter doesn't work but I am not sure.I am attaching photos below. How can I test a component?Thank you

author: Andy Chee
author_rank: Super Contributor
timestamp: February 26, 2024, 11:27:37 am
content: What test equipment do you have?

author: shapirus
author_rank: Super Contributor
timestamp: February 26, 2024, 12:01:39 pm
content: FYI your images are shown as file attachments, not as images, which requires extra effort to view them. Besides, they're huge. For best results, including the willingness of others to help, you should resize them appropriately before posting and attach as images.

author: MrAl
author_rank: Super Contributor
timestamp: February 26, 2024, 02:20:34 pm
content: Quote from: ssport on February 26, 2024, 11:23:50 amWhere is the schematic.Smaller images...
How to check MOC3011 octocoupler - Page 1
Forum section: electronics / beginners

author: giosif
author_rank: Frequent Contributor
timestamp: July 05, 2018, 09:57:37 pm
content: Hi,I am trying to determine if a couple of MOC3011 octocouplers I have are working or not.What I've done in that direction was to put one multimeter in resistance or diode mode, connect its leads to pins 4 and 6, then use another multimeter in diode mode and connect its leads to pins 1 and 2 (red lead going to pin 1).However, although I could see a voltage drop measured by the second multimeter across the IR diode integrated into MOC3011, there was no change with regards to the measurement on the first multimeter - it kept showing OL.Am I testing this correctly?Thanks!

author: wraper
author_rank: Unknown
timestamp: July 05, 2018, 10:00:41 pm
content: MOC3011 has 5mA typ. trigger current, what did you expect?

author: giosif
author_rank: Frequent Contributor
timestamp: July 05, 2018, 10:10:23 pm
content: My expectation was that, upon turning the IR diode on with the second multimeter, a current will be allowed to flow between pins 4 and 6, thus getting the first multimeter to register some resistance (when in resistance mode) or voltage drop (when in diode mode).Are you saying the first multimeter needs to be able to source 5mA of current?I need to check, but I think that shouldn't be a problem for a multimeter in resistance or diode mode.

author: wraper
author_rank: Unknown
timestamp: July 05, 2018, 11:02:50 pm
content: 5mA would be very high current for multimeter.

author: Zero999
author_rank: Super Contributor
timestamp: July 06, 2018, 09:18:53 am
content: If you're using the resistance setting to measure the opto-TRIAC, then the test voltage might not be high enough, since it's likely under the 600mV or so on state voltage of the TRIAC.

author: giosif
author_rank: Frequent Contributor
timestamp: July 21, 2018, 09:00:11 pm
content: Sorry for the late reply!@wraper: you are right, the multimeter wouldn't be sourcing that much current.@Hero999: maybe I am reading your statement the wrong way, but the multimeter would definitely source more than 600mV in resistance mode.Thank you both!
How to check SIOV (PTC Thermistor) C945 - Good or to replace? - Page 1
Forum section: electronics / beginners

author: pppopol
author_rank: Newbie
timestamp: February 16, 2020, 10:40:39 am
content: Hi,I have a doubt about the test of a SIOV (PTC Thermistor) C945 from TDK which tells me to the 0.45 Ohm.See technical data here:https://www.tdk-electronics.tdk.com/inf/55/db/PTC/PTC_OC_Leaded_12V_C945_C995.pdfI find in the datasheet a "Rr" of 0.45 Ohms, is this correct?Is this the value I need to measure?Thank you in advance for your reply.
How to choose a stepper driver? - Page 1
Forum section: electronics / beginners

author: apelly
author_rank: Unknown
timestamp: April 13, 2016, 08:09:39 pm
content: Starting from zero.I've had a box of second hand stepper motors sitting around for a while, waiting for a rainy day. One of my projects needs some coils wound and I was thinking one of those $1 stepper drivers from ebay with an arduino woild do the trick in a couple of minutes. I still think it would. But now I'm wondering more broadly how to select a driver chip. Even amongst the $1 selection on ebay there are a handful of chips.I've brought up this project on here before, it's an electromagnetic stirring hotplate. I was thinking of using some h-bridges for it, but now I wonder if I can get more bang from a stepper driver or two.So that's the back-story, now I'd like to find out what I don't know about stepper drivers. I did do a bunch of reading some time ago, but most of that has slipped into the mist by now.Have you got favourite drivers? Why?Is there a best manufacturer?A best footprint?

author: jeremy
author_rank: Super Contributor
timestamp: April 13, 2016, 10:49:39 pm
content: Most of the differences between stepper motor drivers I have noticed come down to the following:- Microstep ratios- Maximum step frequency- Maximum current to the windings- Support for various motor wiring configurationsIt really depends on how big your motors are, but for a hot-plate stirrer you most certainly don't need good microstepping (nor any microstepping at all really).For what it's worth, I used drivers like these:http://www.ebay.com.au/itm/like/281616135028?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=107&chn=pson a CNC with 420 Oz/in steppers and they work fine. If you have a smaller motor like this:http://2.bp.blogspot.com/-yhKSTGwrIX4/UfrLm60CnOI/AAAAAAAAADM/NY5BMn1oOp0/s1600/stepper_motor.jpgthe A4988s should be fine with a little heatsink; this is what my 3D printer uses.
How to choose diode for step-down ? - Page 1
Forum section: electronics / beginners

author: Odd
author_rank: Regular Contributor
timestamp: January 27, 2021, 08:15:21 pm
content: I decided to usehttps://lcsc.com/product-detail/DC-DC-Converters_MPS_MP2451DT-LF-Z_MP2451DT-LF-Z_C14123.htmlHow should I choose "D1" ?The maximum output current will be well below the rated 800mA at 3,3v , and the input voltage a maximum of 26v (not that I expect it to influence the choice)

author: madires
author_rank: Super Contributor
timestamp: January 27, 2021, 08:45:50 pm
content: fast switching -> Schottkymax. 0.6A -> next higher standard current rating: 1Amax. 26V in -> next higher standard max. reverse voltage: 30V

author: TimNJ
author_rank: Super Contributor
timestamp: January 27, 2021, 09:05:23 pm
content: For a buck converter, the diode should be Schottky to keep the losses as low as possible. The diode see the full input voltage (26V) when the transistor switch is turned on. See below.https://upload.wikimedia.org/wikipedia/commons/thumb/5/52/Buck_operating.svg/300px-Buck_operating.svg.pngForward voltage usually dominates the diode losses, so you should estimate the loss in the diode by If(average) * Vf. Vf depends on current, so make sure to check the graph. Based on the power dissipation you calculate, check the thermal resistance (θJ-A) for the package you chose. For example, SOD-123 might have a thermal resistance around 250°C/W. So, if you calculate 100mW dissipation, then you can expect the die temperature will rise by 25°C (0.1W*250°C/W). This is okay, given normal ambient temperatures. But, obviously, if you calculate 500mW dissipation, then the diode is going to be at or over the junction limit.

author: Odd
author_rank: Regular Contributor
timestamp: January 27, 2021, 09:25:59 pm
content: Thank you.when I look at diodes here;https://lcsc.com/products/Diodes_319.htmlthen it seems to me this would be a more-than sufficient choice:https://lcsc.com/product-detail/Schottky-Barrier-Diodes-SBD_SMC-Sangdest-Microelectronicstronic-Nanjing-MBR130HW_C260260.html

author: wraper
author_rank: Unknown
timestamp: January 27, 2021, 09:32:25 pm
content: Quote from: madires on January 27, 2021, 08:45:50 pmYou may want higher rated voltage. If reverse voltage is close to rated voltage, leakage current, especially at elevated temperatures can be very high (and it will heat up significantly under load). Say 10BQ030 which was mentioned has a whopping 12mA typical leakage current at 30V and 125oC.

author: KT88
author_rank: Frequent Contributor
timestamp: January 27, 2021, 11:48:30 pm
content: Although counterintuitive, you want to run the diode as hot as possible - of course within the limits of reliability. The reason for that is a significantly lower Vf at higher temperatures - thus less losses. This is in particular important as it seems you are running the regulator at pretty low duty-cycle.CheersAndreas
How to choose ir led?? mW/sr? forward current? - Page 1
Forum section: electronics / beginners

author: nandoanalog
author_rank: Contributor
timestamp: April 14, 2016, 07:04:19 am
content: Until now I got my IR leds from ebay by searching ie: "1W 940nm led".But, what if I want to buy from mouser/digikey/rs?? How do I know how much "light" the led emits?

author: McBryce
author_rank: Super Contributor
timestamp: April 14, 2016, 09:40:57 am
content: By checking the datasheet. You'll usually find an Intensity vs. Forward Current graph there.McBryce.

author: danadak
author_rank: Super Contributor
timestamp: April 14, 2016, 10:25:36 am
content: When you go to those sites they have a table oriented product selector, and radient intensitya column in the chart. Sortable, searchable......http://www.digikey.com/product-search/en/optoelectronics/infrared-uv-visible-emitters/524328?k=ledRegards, Dana.
How to choose resistor values for unity gain instrumentation amplifier? - Page 1
Forum section: electronics / beginners

author: dusan
author_rank: Regular Contributor
timestamp: April 28, 2023, 01:32:32 pm
content: I'm using following schematic.TL064IN, +5V 0 -5V. I only need unity gain (I'll use 4 same resistors). How should I choose resistor values? Right now I chose 6.8k (I would have chose 10k but I'm running low on those), I tried both 100k and 1M they all seems to work the same. Which values are better? I'm using DC or almost DC measurement (like 10Hz maybe). I'm measuring close to zero, not sure if that is important deciding factor. Also I will also add another amplifier to the output of this one (10x range, 100x range) not sure if that is deciding factor as well.

author: CountChocula
author_rank: Unknown
timestamp: April 28, 2023, 02:11:25 pm
content: For this application, I don't think you have to be too picky about the resistor values; anything in a wide range is going to work (with some caveats, see below). Particularly if you're worried about precision, the tolerance of the various parts is much more important—ideally, you'd want the resistors to be matched as close as possible.In choosing a value, you typically want to avoid something too small (which draws current, stressing the op amp and creating thermal noise) or too large (which messes with the frequency response by limiting the amount of current available to overcome input capacitance). Since you're working near DC, you could probably throw anything you have on hand between 1k and 1M and I'd bet it would probably work okay.
How to choose the value of emitter resistance of common collector circuit? - Page 1
Forum section: electronics / beginners

author: Michael George
author_rank: Contributor
timestamp: September 25, 2015, 09:59:46 pm
content: Hello everybody,This is my first post in this great forum and I'm a beginner in electronics.I have a question about common collector (emitter follower) configuration. I googled and I understand how it works but I find it is difficult to Design or calculate resistors values especially the emitter resistor.So, Would you tell me how to calculate the emitter resistor in common collector configuration, Please?Thanks in advance,

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 26, 2015, 02:04:03 am
content: You can basically pick a desired bias current, and go....Okay, so how to pick that?How much current do you need to supply to the load? Or what minimum load resistance is expected, and what minimum voltage swing must be created across that load? (I = V/R)If you take that (peak) current, and use that for quiescent current, you're right on the minimum range of class A operation. Maybe choose 50 to 100% more for best results.Often, you can't afford that much bias current. It's very inefficient. Transmitting only 1V (peak) into a 50 ohm transmission line requires 20mA, maybe 30 or 40mA for best results. The base (input) current draw almost becomes significant: max. 0.4mA for e.g. a 2N3904 doing this. If the supply is 12V, that's almost 1/2W being burned by the circuit, which would be terrible for a battery operated device. For these reasons and others, you may need to use a more elaborate circuit (more buffering, to supply the required base current?), or a different circuit altogether (such as a class AB or B push-pull amplifier, which can deliver the high output current without drawing high quiescent current, but requires more transistors).Tim
How to clean up my PCB? - Page 1
Forum section: electronics / beginners

author: rozeh
author_rank: Regular Contributor
timestamp: December 04, 2014, 06:02:27 am
content: I'm trying to get rid of the flux on my board but it seems I have a problem. this is my board:After soldering two memory under the board(as you can see two memory(a RAM and a Flash)), there is a bit flux among the pins and unfortunately under the plastic of the pin-headers. I have used a spray to wash it out but it doesn't good work for me.How to clean it(flux) out? I mean the flux under the plastic of the pin-headers. I also have seen this clip:and I used a combo 50-50% alcohol and acetone but still...I tried to earse the MCU but it's impossible. it seems there are conduction among the pins.

author: Dago
author_rank: Frequent Contributor
timestamp: December 04, 2014, 06:29:51 am
content: Quote from: rozeh on December 04, 2014, 06:02:27 amI doubt the problem with erasing the MCU is due to uncleaned flux. You most likely have some pins short circuited together.For cleaning boards I just use isopropanol (IPA) and a toothbrush. To get no (mainly cosmetic) residue on the board the trick is to dry it up before the IPA evaporates, pressurized air is good for this or just dab it dry with handtowels.

author: marshallh
author_rank: Unknown
timestamp: December 04, 2014, 06:42:28 am
content: What specific type of flux did you use?

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: December 04, 2014, 07:06:20 am
content: IPA doesn't remove flux on contact. That's why Dago is using a toothbrush (as do I.) When a toothbrush doesn't reach, I soak for awhile (moving the board around) and then do a fair bit of rinsing.

author: rozeh
author_rank: Regular Contributor
timestamp: December 04, 2014, 07:31:08 am
content: I use this flux:Ya Xun Yx-20I myself use a toothbrush.

author: Kappes Buur
author_rank: Regular Contributor
timestamp: December 04, 2014, 07:34:49 am
content: https://www.eevblog.com/forum/beginners/removing-potting-epoxy/msg342694/#msg342694replies 3 and 5
How to clear output of step up converter ?  - Page 1
Forum section: electronics / beginners

author: Matthew98
author_rank: Regular Contributor
timestamp: February 21, 2017, 08:15:55 pm
content: Hey. I bught a DS0150 mini osciloscope and moded it to have internal battery. Its 700mAh Lipo and Im feeding the scope, which draws 100mAh at 9V by step up converter. but this converter add significant amount of static to the osciloscope. How do i get rid as much of it as possible ?For now im using only 470uF capacitor as filtration ... dunno what to addThanks !

author: bharatcs
author_rank: Contributor
timestamp: February 22, 2017, 06:14:59 pm
content: HiCapacitor can only filter the output voltage.Since the step up converter is a switching circuits it will produce electromagnetic interference as it is not shielded and can induce voltages in the input circuitry oscilloscope thus creating static.To solve your problem you can-Try to move the step up converter away from the main circuit-Try some shielding method (not sure how to )-Proper grounding

author: Matthew98
author_rank: Regular Contributor
timestamp: February 23, 2017, 01:06:28 pm
content: I will try to shield him than..Mabye aluminum foil will work... I ll have to tryAluminium and iron plates together make a good shielding, they say...

author: Matthew98
author_rank: Regular Contributor
timestamp: February 24, 2017, 09:06:36 pm
content: Update : Its not inducted voltage. I have tried powering it from 9V battery and when i turned on the stepup converter and gave it 100ma, the scope was sill clear.Altough i have figured out something. If I connect the step up converter via long (half a meter ? ) cables, the noise decreases a lot !

author: Refrigerator
author_rank: Super Contributor
timestamp: February 25, 2017, 05:18:06 pm
content: if the current draw is only 100mA then you can put a small inductor in series with the boost converter.

author: Matthew98
author_rank: Regular Contributor
timestamp: February 26, 2017, 12:32:11 am
content: how many H do you reckon ?

author: Refrigerator
author_rank: Super Contributor
timestamp: February 26, 2017, 08:52:07 am
content: 47µH inductor would be a good place to start.Also it would help if you put about 10µF capacitor between the scope and inductor to ground.

author: Matthew98
author_rank: Regular Contributor
timestamp: February 26, 2017, 01:25:47 pm
content: Thanks !So i gave it twice bigger inductor, as i dont have any smaller right now, but it works really well !I did small module out of it, so it can fit inside with no problems. here is how the module looksAnd it scopes quite nice now
How to code this in nRF - Page 1
Forum section: electronics / beginners

author: thun3100
author_rank: Newbie
timestamp: September 27, 2024, 10:50:03 am
content: I having trouble with coding this with nRF. Can anybody help me please?I want to make T1 to last for 4 seconds, while T2 is doubled that of T1, which is 8 seconds.Thanks in advance!

author: pcprogrammer
author_rank: Super Contributor
timestamp: September 27, 2024, 10:58:06 am
content: More information is needed to answer this question. nRF only indicates you most likely want to do it with something from Nordic Semiconductor, but not a specific chip.For someone not familiar with the Nordic line of MCU's a datasheet or reference manual is needed to be able to think up a solution for your problem.

author: selcuk
author_rank: Frequent Contributor
timestamp: September 27, 2024, 01:10:10 pm
content: If you are using nRF5 SDK APIs, there are functions like nrfx_pwm_simple_playback(), nrfx_pwm_complex_playback() etc. for those kind of jobs. You can initially set some frequencies and then it alters the PWM between them based on time.https://docs.nordicsemi.com/bundle/sdk_nrf5_v17.0.2/page/group_nrfx_pwm.html
How to communicate with an LCD with ILI9488 driver in parallel? - Page 1
Forum section: electronics / beginners

author: slow_rider
author_rank: Regular Contributor
timestamp: February 01, 2018, 12:46:15 am
content: I am not sure I understand how the 16 bit "8080" style bus works - what data should I send to it and what is the power up sequence?Anyone has has experience with these?https://www.elecrow.com/download/ILI9488%20Data%20Sheet_100.pdf
How to connect 2 digit 7 pin display? - Page 1
Forum section: electronics / beginners

author: Mario_33
author_rank: Newbie
timestamp: September 23, 2020, 04:32:32 pm
content: Hi, i found an old 2 digits 7 pins display but cant find any info on internet. The display itself has 4 pin but the mini circuit attached has 7 pins. I attaching the photos. Thank you in advance.

author: wraper
author_rank: Unknown
timestamp: September 23, 2020, 04:36:44 pm
content: Discard it. There is no easy way of using it. There should be some sort of driver IC inside it which uses serial interface. If there is marking on the display itself, you might figure out how to use it but it's really not worth it.

author: Mario_33
author_rank: Newbie
timestamp: September 23, 2020, 04:42:23 pm
content: Thank you very much!
How to connect Linear Analog Optocoupler - Page 1
Forum section: electronics / beginners

author: ajoseph88
author_rank: Contributor
timestamp: September 25, 2015, 01:50:10 pm
content: I am using Analog optocoupler HCNR201, to isolate the dc armature voltage from the motor and use it as a feedback.So i am having two confusions,1. I did not understand the pin diagram, and how to connect... data sheet is confusing for me...2. Datasheet says Vf peak is 1.95 volts, so what is that... and how to connect my input of 0 to 5V to get the same output of 0 to 5V with isolation, as there seems to be 6 pins and I suppose i should use a buffer op-amp as well...My god, I am dumb as a donkey... I am one of the dumbest persons in the world trying to learn electronics... Shit...

author: macboy
author_rank: Super Contributor
timestamp: September 25, 2015, 04:36:20 pm
content: Why do you need isolation between the controller and the motor it is controlling?Describe your setup in as much detail as possible.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: September 25, 2015, 06:03:50 pm
content: The datasheet I looked at gives several application circuits, using op-amps, that would appear to fit your application, if I am understanding your needs correctly.This optocoupler has one LED light source inside it, which is driven by the input signal, and two separate phototransistors which are actuated by the light from the internal LED. The "1.95 Vf peak" refers to the forward voltage of the LED, it's just like the Vf figure for any LED or diode. The pinout seems straightforward to me, with two pins for the LED ( one anode and one cathode), and two pins each for the phototransistors (emitters and collectors). (The light from the LED acts as the "base" signal for the PTs.)

author: TimFox
author_rank: Super Contributor
timestamp: September 25, 2015, 06:11:37 pm
content: In an ideal optocoupler, the collector current of the phototransistor is proportional to the LED forward current.In the next approximation, the base current is proportional to the LED current, and the collector current is approximately proportional to that base current (hFE is not truly constant).Of course, all of these currents are unipolar (no polarity reversal).If the two transistors are well-matched, one can give feedback to the LED driver and the second one, galvanically isolated from the first, can deliver current to its load that is well-controlled, being equal to the current in the feedback transistor.
How to connect the 6-pin dual group ON/OFF rocker switch - Page 1
Forum section: electronics / beginners

author: Shonky
author_rank: Frequent Contributor
timestamp: September 16, 2023, 09:31:42 am
content: To what?To do what?How can anyone possibly help with essentially zero information?So you mean a DPDT switch? Double Pole Double Throw?

author: filn
author_rank: Newbie
timestamp: September 18, 2023, 07:36:06 am
content: Yes, the switch type is DPDT. I want to know how many devices it can connect to, and what is the status of each device when the switch is pressed. I want to upload some photos, but this forum is prohibited.Thank you for your help!

author: JustMeHere
author_rank: Frequent Contributor
timestamp: September 18, 2023, 02:00:52 pm
content: Quote from: filn on September 18, 2023, 07:36:06 amPhotos are absolutely allowed on this forum.

author: jonovid
author_rank: Super Contributor
timestamp: September 18, 2023, 05:43:34 pm
content: refer to forum tutorial how to post an image
How to connect these in parallel? - Page 1
Forum section: electronics / beginners

author: PillaDoubleG
author_rank: Newbie
timestamp: March 30, 2024, 10:01:06 pm
content: Hello,For some reason, i dont understand how to connect these two ballasts in parallel.Here i have provided a picture to explain the situation better.https://ibb.co/VYcx7TtAnother thing to add, i don't think that all 4 outputs are needed, only 2 of them.

author: radiolistener
author_rank: Super Contributor
timestamp: March 31, 2024, 12:20:43 am
content: please use the image instead of suspicious link... Many users just don't want to click on unknown link.

author: PillaDoubleG
author_rank: Newbie
timestamp: March 31, 2024, 02:28:37 pm
content: Sorry for that, i put the link because i genuinely have no idea how to post a picture.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 31, 2024, 02:53:05 pm
content: Its easy.Under "attachments and options" below add the image file.Parallel in what sense, from the same input blobs?Life's very hard with only a phone. Get a dumpster PC an make your life easier.
How to connect this sensor?? - Page 1
Forum section: electronics / beginners

author: LostElectron
author_rank: Newbie
timestamp: July 24, 2018, 10:43:28 am
content: Hi folksI want to connect this sensor to this wire. Unfortunately no solder should be used (high temp).I just can't find a ceramic conector or some kind of crimp among the billions of connectos at MouserAny ideas??

author: austfox
author_rank: Regular Contributor
timestamp: July 24, 2018, 12:11:22 pm
content: How about a 2 way terminal block, such as this:https://www.altronics.com.au/p/p2028-dinkle-2-way-3.5mm-pcb-mount-terminal-block/

author: LostElectron
author_rank: Newbie
timestamp: July 24, 2018, 01:18:31 pm
content: I wish...But its a temperature sensor, so it will be exposed to +200C.So no soldering nor plasticI think I found a solution... but ist very very DIY.

author: JS
author_rank: Frequent Contributor
timestamp: July 24, 2018, 01:34:46 pm
content: Maybe you can weld it, like a thermocouple junction, small electric welder with carbon electrode could do. Or spot weld it. Then use high temp insulator.JS

author: tooki
author_rank: Super Contributor
timestamp: July 24, 2018, 04:43:58 pm
content: What about using uninsulated crimps, like a butt or a ferrule?

author: Raj
author_rank: Frequent Contributor
timestamp: August 09, 2018, 04:34:50 am
content: cover the sensor with wer sponge and use solder to connect it to a pcb chunk.

author: Jwillis
author_rank: Super Contributor
timestamp: August 09, 2018, 04:46:43 am
content: 2 Pin Female Single Row Straight Header Connector
How to connect transformer for 230v - Page 1
Forum section: electronics / beginners

author: reddish75
author_rank: Regular Contributor
timestamp: December 16, 2023, 09:53:38 pm
content: Complete brain fart on this and best to check before just connecting, on the transformer pcb attached for 230v primary do I connect the two points shown by red line the live and negative to the other points?Many thanks

author: TimFox
author_rank: Super Contributor
timestamp: December 16, 2023, 10:02:22 pm
content: Yes.The heavy dots represent the winding polarity of the two primaries, so your red line connects the two windings in series properly.The line and neutral then go to the outer connection pins.If you connect the four pins to the connector pads, you can make that connection externally (e.g., at the rear panel of your box).Similarly for the secondary: if you need a series connection (with or without center tap), you connect the center two pins to form it, but if you need a parallel connection, you connect the two "dotted" pins to each other and the other two pins to each other.

author: DavidKo
author_rank: Frequent Contributor
timestamp: December 18, 2023, 06:56:28 am
content: You interconnect 2 middle pins of the connector. Phase and neutral are connected to outer pins.
How to Contact a Manufacture for datasheets (SHARP) - Page 1
Forum section: electronics / beginners

author: ZZT
author_rank: Newbie
timestamp: March 05, 2021, 04:36:11 pm
content: Hi,I'm having a hard time locating a datasheet for a SHARP component LQ065T5CGQ1.I found a document dated August 8th, 2008 that says the part is discontinued, and the suggested alternate part number is LQ064V3DG01.Looking at the datasheet for this new part, I noticed it's not applicable to the part I have in my hands.I've attempted to contact the support numbers listed on sharpusa, and a few of the numbers listed on global.sharp.I can't seem to find any other contacts.How would you normally contact a manufacture for datasheets that aren't available online?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 05, 2021, 04:54:15 pm
content: Sharp was very fast to respond to my decades-obsolete LCD display requestI'll PM you the email I used.

author: ZZT
author_rank: Newbie
timestamp: March 05, 2021, 05:05:09 pm
content: I sent them an email, Hopefully they'll have it haha.I was also given a site that actually has reseller contact information encase it helps anyone.https://www.sharpsecd.com/#/contact

author: Benta
author_rank: Super Contributor
timestamp: March 05, 2021, 05:06:07 pm
content: Call the local franchised distributor. Manufacturers don't take calls from private people or smaller customers.

author: ZZT
author_rank: Newbie
timestamp: March 05, 2021, 05:11:26 pm
content: I was only able to get that contact url via a chip resellers support. I couldn't find any other contact information.I'm calling a few of them to see if they have any other information too, while waiting for an email back.Thank you for the guidance, it did take me abit too long to realize that contacting a distributor is one of the things I should attempt
How to control the current of a transformer welder electronically - Page 1
Forum section: electronics / beginners

author: robsims
author_rank: Frequent Contributor
timestamp: September 29, 2022, 03:57:33 pm
content: Hi, i have a transformer welder with an adjustable magnetic shunt. I want to remove the shunt. Question is, how can i control the welding current electronically? If you read this and have done this before ir know how to, please share you're information. Many thanks in advance
How to control these MOSFETS and BJTs --- Active High or Active Low? - Page 1
Forum section: electronics / beginners

author: snoop911
author_rank: Newbie
timestamp: October 03, 2015, 04:25:18 am
content: Hi,Wondering if someone can help me decipher a motor control driving circuit...If I'm reading the circuit on the left correctly, to place Vin on PhaseA, you would drive the AH control line HIGH. Similarly, to short Phase A to ground, the AL signal going to the N-Mosfet must also be Active HIGH. And AH and AL must never be driven High at the same time, or else this would short VIN to GROUND, Is this correct?The circuit on the right however, has N-BJT AND MOSFETS connected together, so not sure how to read this.. would HW and LW be active HIGH or LOW in order to connect Phase W to either V_MOTOR / GROUND?Thanks!Ben

author: LukeW
author_rank: Frequent Contributor
timestamp: October 03, 2015, 05:02:12 am
content: When HW is high then Q6 pulls the Q3 gate low, turning that P-channel FET on, and turning the half-bridge output high.What's the Q6 emitter connected to? Ground I guess but it's not shown.When LW is high the N-channel FET on the low side is turned on, and the output is low.They're both "active high" inputs to control both the high-side and low-side FETs.But LW is connected to the Q9 gate via that 100-ohm resistor, so Q12 can override that and force the gate low when HW is high, even if LW is also high.This provides protection against the shoot-through state.The left circuit uses two N-channel FETs instead of one N and one P. This has a number of advantages, eg. simplifying the BOM and components logistics and manufacturability. It's easier/cheaper to get better high-power N-channel FETs, so the whole bridge is built using N-channel including the high side.The gate driver IC (IR2101) has a number of functions, including shoot-through protection taken care of for you, driving the FET gates so they turn on well, and a charge pump to provide the right bias voltages (a little bit higher than the Vm rail) ensuring that everything is biased correctly, including the biasing of the high-side FETs (which allows N-channel FETs to be used - note that the source is not at ground, so the gate voltage has to come sufficiently high relative to the source.)

author: snoop911
author_rank: Newbie
timestamp: October 03, 2015, 04:47:47 pm
content: Thanks! Good catch, Q6 is connected to ground via a 180 ohm pull down.So the left/Cypress circuit uses the IR2101 to protect and boost the gate voltage to the source-follower mosfet... but in both circuits, the driving logic from the controller would be active high in order to engerize the upper or lower motor phase.BTW, my goal is to use the circuit on the right, but with a Cypress PSOC developement board that is originally intended for use with circuit on the left. Both use a 12V motor.The backemf from the circuit on the right is scaled down to .18 of V_Motor, while the Cypress circuit scales it down to 0.1. I'm hoping this won't matter, since for zero crossing detection, the psoc4 just compares when the backemf voltage falls below 1.19V.Do you see any potential gotcha to look out for?Thanks!
How to convert 24-48vdc to 220v DC? - Page 1
Forum section: electronics / beginners

author: Kedar264
author_rank: Regular Contributor
timestamp: February 16, 2018, 09:19:04 am
content: Hello everyone so I am going to make electric controller for my bike I am using high voltage motor which works on 240 volts . The voltage can be AC or DC so I am looking for a controller which will produce 240 volts DC from 24 volt 48 volt dCI tried many Chinese inverters but they are not reliable . I also tried commonly available 600 watt 1200 watt dC to DC Converter they can only output 80 volts so that's the limitAs a workaround solution I can connect DC to DC converters output in series but I don't think this can be the only solution you know any kind of a better solution please let me know

author: Jeroen3
author_rank: Super Contributor
timestamp: February 16, 2018, 09:28:48 am
content: Usually you just have more batteries in series to get a higher voltage.

author: Kedar264
author_rank: Regular Contributor
timestamp: February 16, 2018, 09:39:31 am
content: Quote from: Jeroen3 on February 16, 2018, 09:28:48 amThat's true but I can only fit 6× 12v battery in my application so is there any better option?

author: Seekonk
author_rank: Super Contributor
timestamp: February 16, 2018, 05:03:36 pm
content: I'd find an old broken 24V inverter. I have a couple I've chucked the H bridge section of and just run DC out to power things. Older ones have a TL494 switch mode chip and are easy to modify for adjustable voltage.

author: Zero999
author_rank: Super Contributor
timestamp: February 16, 2018, 08:00:09 pm
content: Quote from: Kedar264 on February 16, 2018, 09:39:31 amWhat batteries are you using? Is it possible to use more, smaller batteries?Can't you get a lower voltage/higher current motor?It may be fun to hack what you have on hand to fit your application, but it certainly isn't good design practice. It seldom works out cheaper or more reliable than buying the correct components, in the first place.

author: Benta
author_rank: Super Contributor
timestamp: February 16, 2018, 08:07:55 pm
content: My guess is the OP has chosen a universal motor from an angle grinder, hand drill or the like... not the best choice, but cheap and easy to get hold of.

author: Zero999
author_rank: Super Contributor
timestamp: February 17, 2018, 01:18:25 pm
content: Quote from: Benta on February 16, 2018, 08:07:55 pmThe downside is it requires a DC:DC converter, which is not easy and cheap to get hold of. It also reduces the efficiency of the system.Perhaps use a larger universal motor designed for a 120V appliance and underpower it at 48V? The downside is it will be bigger and heavier, than a 48V motor.
OWERTY - Page 1
Forum section: electronics / beginners

author: pranav
author_rank: Contributor
timestamp: April 25, 2017, 12:12:30 pm
content: ...

author: Molenaar
author_rank: Regular Contributor
timestamp: April 25, 2017, 12:52:30 pm
content: Look up the Mazilli driver, that should do quite well.

author: Seekonk
author_rank: Super Contributor
timestamp: April 25, 2017, 03:25:41 pm
content: That transformer will produce DC with its internal diode.

author: Zero999
author_rank: Super Contributor
timestamp: April 25, 2017, 08:56:32 pm
content: The simplest way I know of.http://madlabs.info/flyback.shtml

author: james_s
author_rank: Super Contributor
timestamp: April 26, 2017, 12:49:45 am
content: These are some others, I've built the mk II one and it works nicely.http://uzzors2k.4hv.org/index.php?page=flybacktransformerdrivers

author: pranav
author_rank: Contributor
timestamp: April 26, 2017, 12:55:41 pm
content: Thanks. I've made a single transistor driver with 2N3055 but the spikes killed by 2N3055Sent from my Lenovo S850 using Tapatalk

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 26, 2017, 12:59:32 pm
content: Quote from: pranav.appu.472 on April 26, 2017, 12:55:41 pmThat's what the circuit is designed to do, by the looks of it.Tim

author: Zero999
author_rank: Super Contributor
timestamp: April 26, 2017, 01:00:32 pm
content: Quote from: pranav.appu.472 on April 26, 2017, 12:55:41 pmWell the circuit I posted above doesn't use the 2N3055 but the NTE284, which has a much higher voltage rating then the crappy old 2N3055. Failing that, try adding a snubber network.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 26, 2017, 02:46:34 pm
content: This is a bit more responsible of a design,And yes, for once I'm claiming a 555 is useful for something.+V can be whatever. For instance, you can use about +100V and use the primary winding inside the FBT itself (trace the PCB to find these pins). For the external winding (usually 3-10 turns), 12-24V will be suitable.An RCD peak clamp snubber, across the transistor, might also be a good idea, to prevent overvoltage. The RC damper helps, but doesn't limit the peak very much.I don't have a complete schematic handy, but you would add a diode, resistor and capacitor, connected to the transistor collector/drain just as Q3, D1, C2, RL are connected here:https://www.seventransistorlabs.com/Images/AltiumDiscreteFlybackSch.pngTypical values would be D1 = UF4007, C2 = 10nF and rated at least 2 x +V, RL = 10k 5W or thereabouts (depending on +V, turns, operating frequency, power level, etc.). You want RL to be small enough that the clamping voltage (the DC voltage on C2) isn't obscene.Tim