hybridfree/eevblog-posts huggingface dataset:
NCP5901 mosfet driver problem! - Page 1
Forum section: electronics / beginners

author: step_s
author_rank: Regular Contributor
timestamp: March 24, 2016, 05:18:42 pm
content: Hi EEVblog.I have wanted to do a project with a PIC controlled buck converter, and for this project the easiest solution is a mosfet driver.I ordered the NPC5901, since this a synchronous mosfet buck driver, and am now testing it.Datasheet:http://www.onsemi.com/pub_link/Collateral/NCP5901-D.PDFThe driver works, even when connected to the gates of the 2 N channel mosfets. The high side out will turn on when the PWM goes high, and the low side out will turn on when the PWM goes low. The tri-state option works aswell, when giving the PWM a steady 2v, keeping both outputs low. (Reading datasheet might shead some light on this).The problem occurs as soon as I connect source of the lowside mosfet to ground. When this is connected, it will no longer accept going from a PWM pulse, to the tri-state mid section.When I try this, the driver will go into a "fault mode" of sorts, where the high side output is low, and the low side output is high. It will be stuck here until the power is disconnected. Not even pulling "Enable" pin down, will shut it off.I'm driving it from 5.4V, and the PWM is supplied from a PIC. The driver works when everything is connected fully, and the PWM is going before the power is turned on, but again, changing the PWM input to 2v will put it into fault mode.I noticed a cap between the SW pin and GND, in the datasheet, but connecting one seems to mess up the driver aswell.What is going on here?

author: ee_man2571
author_rank: Newbie
timestamp: January 05, 2022, 03:08:39 pm
content: Hello,Were you able to solve this issue?

author: Terry Bites
author_rank: Super Contributor
timestamp: January 05, 2022, 05:31:02 pm
content: See section of data sheet on power on reset.The chip will latch off under some fault condtions.
NE555 and switching PSU - Page 1
Forum section: electronics / beginners

author: mazza85
author_rank: Newbie
timestamp: July 14, 2012, 12:39:16 pm
content: I've made a very simple garage door alarm using this circuithttp://www.kpsec.freeuk.com/projects/lalarm.htm, modified by eliminating the 100k trimmer, 22uF electrolitic to replace the 10uF for longer bleep duration and using a magnetic reed switch instead of the LDR. THe output drives a relays via a bc547 transistor.When the circuit is powered by a 12V battery pack everything is fine (especially the power-on reset).If I power the circuit with a switching wall wart the power-on reset don't work (the output is high at the start).How ca I solve this? Or I have to use a linear power supply (LM7812 p.e.) ?

author: SeanB
author_rank: Super Contributor
timestamp: July 14, 2012, 12:50:52 pm
content: Make the 0.01uF capacitor 0.22uF, to give a longer reset time. Most likely the power suply is slow to rise in voltage. Add an additional 100uF 16V capacitor across the power pins of the 555 as well, pin 1 and 8. This should solve it.What is the voltage output of the wall wart?

author: Zero999
author_rank: Super Contributor
timestamp: July 15, 2012, 12:41:31 am
content: Have you measured the output voltage from the wall wart?Some cheap wall warts have no voltage regulation (yes even if they're switch mode) or it may have a minimum load current requirement.

author: mazza85
author_rank: Newbie
timestamp: July 15, 2012, 11:07:36 am
content: Thanks for the answers.Made the modification as suggested by SeanB ( new schematic attached) but the circuit still sometimes triggers at the power-onI've measured the output voltage: unconnected 10,66 V / connected to the circuit 10,48 VI've noticed also that if I touch with a screwdriver or a lead from the dmm either the Vcc, the GND or the base of the BC548 the circuit triggers

author: SeanB
author_rank: Super Contributor
timestamp: July 15, 2012, 11:56:04 am
content: That is mains hash from the switching power supply triggering it then. Change the 1M resistors on pin2 and on the transistor to a lower value, around 10k will do. You might need to use a linear power supply, or connect the negative lead of the supply to an earthed object, or to a earth spike just outside the door.

author: Zero999
author_rank: Super Contributor
timestamp: July 15, 2012, 04:13:29 pm
content: Quote from: SeanB on July 15, 2012, 11:56:04 am]Good point.It also may be the mains being coupled across the Y capacitors in the SMPS. Another option would be to connect both power supply rails to earth/ground with 100nF capacitors, if complete earth bonding is not desirable for some reason.
NE555 Police siren toy schematic - Page 1
Forum section: electronics / beginners

author: mensbufo
author_rank: Newbie
timestamp: February 16, 2023, 07:11:05 pm
content: I found this police siren schematic on the internet. At first it seems really strange to me that on the first ne555 pin 2 and 3 are not marked, but I build something similar in falstad, connected pin 2, 3, 6 on the first ne555 and it worked??? But when I build it in real life, it doesn't work, just squeal and two ne555 got really hot. Is there problem with this circuit, because it seems strange. I really tried to check all possible misconnections and all the details before I solder it. Thanks for help!

author: Zero999
author_rank: Super Contributor
timestamp: February 17, 2023, 12:16:06 pm
content: It should work. The voltage on C1 controls the frequency of U2.Treat 555 circuits as two separate oscillators.What's the waveform on pin 3 of U1? If you don't have an oscilloscope, connect pin 3 to a 1k resistor in series with an LED to 0V. The LED should flash.

author: BillyO
author_rank: Super Contributor
timestamp: February 17, 2023, 12:23:01 pm
content: On the first 555, pin 2 is connected to pin 6 (pin 2 is just not marked). Pin 3 should be left unconnected.

author: mikerj
author_rank: Super Contributor
timestamp: February 17, 2023, 01:37:12 pm
content: If you are using a bipolar NE555 rather than one of the CMOS equivalents, then it's important to have bypass capacitors connected very close to the supply pins of each device. 100n should suffice.
NE555 - schmitt trigger with dual power sourcee - Page 1
Forum section: electronics / beginners

author: bonzer
author_rank: Regular Contributor
timestamp: May 03, 2020, 06:15:29 pm
content: Hello everyone, please help me to understand a thing.I heard that ne555 can also work with dual power supply. I want it to be configured in Schmitt Trigger and give me at the output +15 and -15. I also want negative thresholds.I would connect negative power to GND but would it work? There's the internal flip flop, I don't know if it would work. I would keep CV and THRS to ground as I did in the schematic. I've been looking for any information about it in a couple of datasheets but I didn't find anything.See the attachment.

author: not1xor1
author_rank: Frequent Contributor
timestamp: May 03, 2020, 06:54:33 pm
content: Quote from: bonzer on May 03, 2020, 06:15:29 pmNE555 max supply voltage is 15V so you might use +/- 7.5V and get on the output something around +/-7VIt might be better to just use a single supply (+15V) for the NE555 and then add a PNP or PMOS to invert the output between something close to +/-15V

author: bonzer
author_rank: Regular Contributor
timestamp: May 04, 2020, 07:32:49 pm
content: Thanks for your answer.I have another question, please anybody answer if you know.I found this configuration surfing on the internet and it's popular.Is it actually necessary in your opinion to keep those 100k resistors? I've read that it's used to bias the input to the center of the variation range. They also put a coupling capacitor to TRIG pin which I removed. This way they kinda center the variation of the signal to the average between the two thresholds.I removed that capacitor because I can actually accept my input signal to change to that specific thresholds with the required DC component. Therefore I want to remove also the two 100k resistors. Do you think there's no problem with that?

author: Zero999
author_rank: Super Contributor
timestamp: May 10, 2020, 09:46:41 pm
content: If the input is not AC coupled, then there is no need for the resistors.
NE555 wont work on 5Vdc ? faulty ? - Page 1
Forum section: electronics / beginners

author: tonny_cassidy25@yahoo.com
author_rank: Newbie
timestamp: July 25, 2015, 09:15:35 am
content: so yesterday i found a 555 ic that i bought 2 month ago after doing some experiment with it 2 month ago i removed it from my prototype and throw it into my ic box,yesterday i fount it and i build a 100khz oscillator (84% duty cycle) with it and it works just fine on usb 5v power,so today i bought a new ne555 and build another prototype with the same circuit and the new ic wont work on 5v ,i bought 4 pieces of it and all of them doesnt work on 5v,according to the datasheet the minimum vcc is 4.5v,faulty chip (new one) ? or old one because it have been used for other experiment before ?

author: sleemanj
author_rank: Super Contributor
timestamp: July 25, 2015, 09:29:51 am
content: Put working chip into the non-working circuit and see if it works - ie, maybe you made a mistake when you recreated the circuit.

author: tonny_cassidy25@yahoo.com
author_rank: Newbie
timestamp: July 25, 2015, 09:51:38 am
content: i do,but still doesnt work,i do realize that i bought the previous chip from different store

author: fcb
author_rank: Super Contributor
timestamp: July 25, 2015, 10:06:03 am
content: Check your layout - very unlikely to be the IC (unless you abused it in the past).
Near field distance vs frequency - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: October 07, 2017, 05:33:17 am
content: I have read many times that near field is proportional to wavelenght,with longer wavelenght providing longer near field.I have tried two online calcularor where you input wavelenght and antena lenght and it show you how far away the near field reaches.The results from both of these calculators are exact oposite of what I have read before,it shows near field extending further away the higher the frequency is!I dont know what to believe,so does it increase or decrease with frequency? Either these calculators suck,or literaly every single article on near field I have ever read is completly wrong.https://www.everythingrf.com/rf-calculators/antenna-near-field-distance-calculator

author: Neganur
author_rank: Unknown
timestamp: October 07, 2017, 08:40:35 am
content: I'll give this a shot.Those equations are for electrically large antennas (think dishes or horns). Since they generally have a high directivity, the reactive near field extends significantly in the direction of radiation. In fact, it is not uncommon that fulfilling the far field criterion becomes impractical and you have to live with measurements in the near field (EMC).For electrically small antennas (largest feature of antenna is much smaller than the wavelength) the far field is at distances greater than two wavelengths This may suit your intuition better since maybe most antennas you had in mind are actually el. small like inverted F or a pocket radio's FM antenna?
Cheap Near field measurements for preparing product for radiated emissions test - Page 1
Forum section: electronics / beginners

author: ocset
author_rank: Super Contributor
timestamp: February 07, 2021, 03:13:42 pm
content: Here is a good question for an EMC sub_forum that could if wished, be added to this website?How do proper EN55032, far field radiated emissions scan plots correlate with plots obtained cheaply with near field probes?In other words, if we do a proper radiated emissions scan plot......and then we change a filter component, and the re-done radiated scan comes out worse....would the re-done near field plot also come out worse? (and vice versa)

author: TimNJ
author_rank: Super Contributor
timestamp: February 07, 2021, 07:32:13 pm
content: We have a TekBox TBCP1-250 RF current probe. Put it on the AC input cord.You can take a look at this:https://www.tekbox.com/product/AN_-RF_current_to_electric_field_strength_extrapolation.pdfMy recommendation is to run a real, preliminary scan at an accredited lab as a baseline. Then use your current probe measurements while you make changes to your circuit/system. Once the current probe measurement shows enough improvement, go back to a real lab and confirm.

author: Simon
author_rank: Unknown
timestamp: February 08, 2021, 12:36:49 pm
content: https://www.eevblog.com/forum/renewable-energy/cheap-near-field-probe-and-emc-analyser-for-radiated-emissiaons-of-smps/msg3451738/#msg3451738
Neat little calculator for electronics - Page 1
Forum section: electronics / beginners

author: Deathwish
author_rank: Unknown
timestamp: June 05, 2015, 07:00:25 pm
content: If you want a neat windows calculator for capacitors etc etc for your desktop, try this one. you can also download it free.http://www.electronics2000.co.uk/download.php?source=ea_calc_ad#epeindex

author: timofonic
author_rank: Frequent Contributor
timestamp: June 16, 2015, 04:48:57 am
content: Quote from: Deathwish on June 05, 2015, 07:00:25 pmI like this app and there isn't something similar for Linux

author: Falcon69
author_rank: Super Contributor
timestamp: June 16, 2015, 04:58:44 am
content: I've got a similar app on my smart phone! Love it.
Neat Variable capacitance video from 2014 by VK2ZAY - Page 1
Forum section: electronics / beginners

author: cdev
author_rank: Super Contributor
timestamp: December 30, 2020, 02:51:56 am
content: I learned a ton of stuff from this video, and this is a subject I am really into.Magloops in particular are like a huge "something for nothing" as far as radio performance is concerned, IMHO.And variable capacitors are what makes them sing, literally.Here is the article URL. (But the content is mostly a video)http://www.vk2zay.net/article/270At the beginning he shows a capacitor that reminds me of a magnetic loop that I built a couple of years ago out of a single "blade" from a window shade - it worked quite wellI also used (cheap) aluminum tape.I guess that capacitor was also a variable inductor at the same time.Indeed it was.https://youtu.be/_Tpnak5DwpQI think my SO may have thrown it out. Although she actually is pretty good about that, so who knows, it may turn up.it really did look like a worthless piece of junk. (and exactly like the other pieces of the shade which we did throw out, with the exception of the aluminum tape on one side).A great stealth antenna.
NEC Japan IC,s Database - Page 1
Forum section: electronics / beginners

author: hugh
author_rank: Newbie
timestamp: June 30, 2012, 06:49:01 pm
content: Hello guys. is there any place where you can search for NEC Japan IC's. I'm looking for data sheets for D1714GT or 06700GH. Very hard to find for me after hours of web search. Any ideas?Cheers from Venezuela.. Thanks

author: free_electron
author_rank: Super Contributor
timestamp: June 30, 2012, 07:48:20 pm
content: it helps if you put 'up' before the part number. most nex partnumbers begin with 'up' but the don't print it on the bodysame for transsitors A123 -> 2SA123 , K408 -> 2SK408. this is common for japanese parts.D1714 -> UPD1714.some 4 bit processor or processor peripheral. custom rom.

author: hugh
author_rank: Newbie
timestamp: June 30, 2012, 09:36:07 pm
content: Thanks for the heads up about the "UP" prefix. Indeed, it is a SMALL, GENERAL-PURPOSE4-BIT SINGLE-CHIP MICROCONTROLLERS used in automotive applications. It is mounted in my Toyota Land Cruiser clinometer unit. Im trying to fix the external temperature measurement. Now I have the info I need.

author: free_electron
author_rank: Super Contributor
timestamp: June 30, 2012, 10:58:36 pm
content: Not going to find that thing. it is a mask-rommed device custom made for one customer.
Nec np300 led conversion - Page 1
Forum section: electronics / beginners

author: qazuio
author_rank: Newbie
timestamp: April 28, 2016, 10:34:02 pm
content: Can anyone help me, I'm trying to get an NEC NP-300 projector to stay on without the lamp?I've posted on another dormant thread here with no replies.I know the np300 uses an USHIO ballast, I also have an Arduino Uno, have tried the serial stream posted from fellow member "bowlofpudding" for an NT48 on my Arduino;https://www.eevblog.com/forum/beginners/video-projector-ballast-bypass-help/it does not work for me, either the code is not compatible with my model or the beamer is not happy with a 5 Volt signal instead of the expected 3.3?Regardless, I know this bypass approach is possible as I have run another unit with a good lamp and connected pin 1 from it to pin 1 on the other unit without the ballast and both stay on with identical status lights.So my question is, does anyone know how to go about recording the pin 1 signal and pasting it into a (void loop?) for playback?Help please :-) then I can move on to the next stage, ie, installing an LED and driver.Can also post updates for other members interested in my progress.Thank-you,David
Necessity of swaping safety capacitors - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: April 30, 2020, 03:07:51 am
content: I understand that in older designs, that may have less than ideal means of managing line voltage safety, a lot can and should have their capacitors "death caps" replaced. (At least this is true of older tube amps and such)While inspecting a bench PSU, i noticed the hot mains line has a Y5U 1KV going across is, i'm not sure, is this adequate or should i be putting something like a X/Y film cap in its place?It seems like a part that can only be bought NOS or from China (probably fakes) so i am not sure if it's actually properly safe in there or if it's best left alone.

author: Vovk_Z
author_rank: Super Contributor
timestamp: April 30, 2020, 10:40:16 am
content: If it is across mains and doesn't have safety certificates on it (so it isn't X/Y rated) then you can change it to Y1/Y2 one (to not worry).

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 30, 2020, 01:36:06 pm
content: The Rifa caps in mains filters seem to have a reputation for letting out big amounts of magic smoke. Especially those rolls of aluminimum foil in transparent plastic that grows yellow and crackling over time. Even Davey Jones has it in one of his vid's. I believe it was on a big power supply tester rig, that (among other things) can inject spikes and surges into the mains side of a test appliance. Video is (approx) one years old I guess.

author: Mp3
author_rank: Frequent Contributor
timestamp: April 30, 2020, 08:53:46 pm
content: I appreciate it, i'll be sure to order some Class Y's to replace it! And I'll check those vids. i have some of those crackley looking yellow caps in my HP 3478a as well. Better take care of them all...

author: vk6zgo
author_rank: Super Contributor
timestamp: April 30, 2020, 11:33:54 pm
content: Quote from: Mp3 on April 30, 2020, 03:07:51 amMostly, old tube amps don't have such capacitors at all, as they have massive power transformers & linear power supplies, so don't generate any switch mode power supply noise, which is one (the main) reason these capacitors are there in the first place.The others are to keep out noise incoming on the Mains, which can interfere with sensitive instruments, or RF from signal generators, etc, being coupled out onto the Mains.My old Leader LSG-11 sig gen has a ceramic cap, apparently for this last purpose, but it is the first thing that is going to "that big parts bin in the sky" when I get around to refurbing it.
Neebee power supply build - Page 1
Forum section: electronics / beginners

author: zippy500
author_rank: Newbie
timestamp: September 12, 2014, 08:23:21 pm
content: Hi everyone,As a start project I would like to build a 0-30v variable power supply.I have come across this circuit;http://www.electronics-lab.com/projects/power/001/Is this a good starter project ? or can someone recommended a circuit to build ?What I'd really like to incorporate is a Voltmeter and a Ampmeter, can anyone tell me which part of the circuit I need to incorporate theseThanks

author: paul18fr
author_rank: Contributor
timestamp: September 12, 2014, 08:48:19 pm
content: follow this post (same PSU)https://www.eevblog.com/forum/beginners/power-supply-design-(2)/

author: liquibyte
author_rank: Frequent Contributor
timestamp: September 12, 2014, 09:00:48 pm
content: The circuit works and I have built two of them but it suffers from a transient voltage issue on startup. You need to read the threads about it over at their forums because the project you linked to suffers from underrated components and has been reported to fail. See my posts about adding Q1 with its voltage divider back in too, it solves a shutdown transient. You'd hook the voltmeter across the output and the ammeter across R7 if you want to measure the load current or from ground to pin 3 if you want to translate the 0-1.41V to 0-3A through a voltmeter circuit to show the current limit setting. The latter is how I'm going to do it. If you do build one, don't hook it up to anything sensitive before turning the power on. At 30V you'll see around a 6V spike.

author: David Hess
author_rank: Super Contributor
timestamp: September 17, 2014, 05:34:48 am
content: We went through that design in the discussion paul18fr linked and came up with some improvements but did not solve the voltage surge on startup problem which I consider a serious issue. I would look for a different design.

author: zippy500
author_rank: Newbie
timestamp: September 18, 2014, 09:16:14 pm
content: can anyone suggest a different design- Im very new to this !Thanks
need 5.9-6 inch tft display with hdmi in - Page 1
Forum section: electronics / beginners

author: umutkoker
author_rank: Newbie
timestamp: October 17, 2017, 10:21:01 pm
content: I bought 5.9 - 6 inch displays with hdmi dsi driver board from different manifacturers, we want to use this on our mass production vr glasses.But they all doesnt work with our 1920x1080 resolution device (i think because of their 1080x1920(portrait) resolution). If we plug them to a pc they are working well because pc supports this 1080x1920 resolution. But we dont want to plug it to a pc we want to plug it to a device that supports 1920x1080 resolution.Do you know a solution for that ( for example another control board)I need your help,Yours,Tan

author: danadak
author_rank: Super Contributor
timestamp: October 17, 2017, 10:49:43 pm
content: You will need another controller board, or look at controller chipon the board you have to see if it would be capable with firmwarechanges to support the higher resolution. If it can contact boardvendor to see if that is a possibility.If you need another controller board you will need cabling to connectdisplay to board.Regards, Dana.

author: umutkoker
author_rank: Newbie
timestamp: October 18, 2017, 09:25:37 am
content: Hello Dana, I am using the 1920x1080 resolution 6 inch displays that are manifactured for vr glasses in aliexpress. I am searching the internet for days but all the displays driver cards are the same (1080x1920 portrait resolution);I think because of 6 inch mostly use with phones. I cant know where to find a board with a regular landscape 1920x1080. I am getting crasy..
Need 5v->12v conversion - Page 1
Forum section: electronics / beginners

author: bitman
author_rank: Unknown
timestamp: September 27, 2020, 10:08:24 pm
content: I have a small halloween display I need to control the lightning frequency (PWM). I have something that works but it really looks over-engineered and I wondered if there are simpler designs?I have two power LEDs that I can run at 12V and just about 1.5A to be really bright. They're mounted on heat sinks etc. I would like to regulate the power (mosfet) from the Wemo D1 (ESP8266) which in this setup spits out 5v PWM signals. I tried to just use a BJT on the 5V but it won't drive enough amps - my BJTs all max up before 1Amp so looking at what I had, I grabed an IRF540N (mosfet). Just using this mosfet and a trimmer (voltage divider) I can easily adjust the brightness of the light. I need this feature so I can adjust the maximum brightness.So to do this I power from 12V and regulate the power for the Wemo using an old fashion 7805. I then use a BJT/NPN on the PWM output from the Wemo to control the signal from the pot to the mosfet. I'm well aware of the voltage drop but enough is coming through that I think the maximum brightness will be just fine.This seems over-engineered. Of course I cannot just use a voltage divider as the voltage is going up. I also need to be able to pul this as close to 0 as possible.I'm wondering if going with a single opamp would do better here? But it would only save me one component so it doesn't seem like that big of a difference.What are my options given I need to drive about 1.5A/12V (peak)?

author: nachus001
author_rank: Contributor
timestamp: September 28, 2020, 03:21:30 am
content: The correct way to do pwm for LED intensity isConnect the npn transistor via two 4k7 resistorsFrom a pwm pin of the controller. Emitter to groundcollector to 1k resistor yo 12v. Collector also to MOSFET gate. Mosfet's source to ground, and LED cathode to drain.LED anode to 12v. For this apps, maybe it's better an irfz44 mosfet.IgnacioThe potentiometer may be tied between 5v and ground, and the cursor yo an ADC input.You'll need the software to convert from analog input to pwm output
Need a (slightly) random signal ?   Hers an idea, using CDS light sensor. - Page 1
Forum section: electronics / beginners

author: RJSV
author_rank: Super Contributor
timestamp: April 28, 2024, 01:59:33 am
content: Hello there!After purchasing one of those cheap 'Garden Lamps' it was amusing to watch and contemplate the 'flicker' signal that gets generated. It's a slow candle-like effect, that COULD be useful as an optical signal source...in this case as an informal signal gen.Simply couple your extra CDS sensor, that will be round, with glass front, and, usually, some visible track line grid. I've found the sensor is good when placed as a replacement for single resistor, like in some 555 or Lm311, or Lm339 type oscillator circuit.The sensor usually is in range of about 500 ohms, so when putting in place of, say, 10 kohms, best to put about a 3k to 5 k in series, so you get around 10k, but with variations, according to light levels.The solar device LED, (I've assumed) is made to flicker, by some simple processor.OMG, ...?? Are the light flickers generated inside the output LED, itself ?In that case would need to put simple current monitor and LM324 OPAMP buffer, to follow the small current fluctuations.

author: RJSV
author_rank: Super Contributor
timestamp: April 28, 2024, 02:03:21 am
content: My bad, as you STILL get the optical signal, so only need the CDS sensor....(stupid mistake, sorry).Also useful when experimenting with light sensing diodes ...

author: RJSV
author_rank: Super Contributor
timestamp: April 28, 2024, 04:04:49 am
content: Picture of solar night lamp.

author: RJSV
author_rank: Super Contributor
timestamp: April 28, 2024, 07:31:38 pm
content: Here is a daytime view, of the solar garden lamp, with simulated yellow 'candle flicker'.
Need a bit help - edeting a smal schematic. - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: March 31, 2022, 01:29:05 pm
content: I have found this small amplifier circuit and want to build it, but to make it function do I have to follow some instructions.One of the instructions say that I shall copy the current source on Q3 collector to the I1 current source, but modify it to deliver 2 mA.I have no idea on what components to copy and how to connect them, would you please help :-)

author: m k
author_rank: Super Contributor
timestamp: April 09, 2022, 03:49:20 pm
content: Why it's not a complete circuit?

author: TimFox
author_rank: Super Contributor
timestamp: April 09, 2022, 03:58:55 pm
content: The "current source on Q3 collector" seems to be somewhere off-screen past the bottom of the drawing you posted.Nothing shown around Q3 is a DC current source.

author: Terry Bites
author_rank: Super Contributor
timestamp: April 10, 2022, 03:51:04 pm
content: I think you have croped that schematic a bit too tight- can you provide better image?

author: magic
author_rank: Super Contributor
timestamp: April 10, 2022, 04:03:30 pm
content: Q3 collector is likely connected to the negative rail in this arrangement, they probably meant the source feeding Q3 emitter.

author: TimFox
author_rank: Super Contributor
timestamp: April 10, 2022, 04:07:18 pm
content: Yes, Q5 and Q13 are a standard DC current source connected to theemitterof Q3. R36 sets the current level, but it's not clear from the cropped circuit what the relevant voltages are.

author: magic
author_rank: Super Contributor
timestamp: April 10, 2022, 04:32:04 pm
content: Q5 and Q13, because the author didn't care much about numbering them in any logical orderAlso, current is set by R30 (Vbe/R30 or ~4mA) and R31 is probably not making much difference unless it's necessary for somethnig not visible here. R36 provides base current to Q5 and collector bias current to Q13.This is so-called "two-transistor current source", you should have no trouble finding information about it.

author: TimFox
author_rank: Super Contributor
timestamp: April 10, 2022, 04:34:01 pm
content: Thanks. I corrected the transistor numbers in my post above.
need a code for Inverter - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: March 01, 2019, 06:28:09 pm
content: Hello guys I need a code for inverter using micro controller(PIC).Can anyone help me??

author: rstofer
author_rank: Super Contributor
timestamp: March 01, 2019, 07:07:09 pm
content: What kind of inverter? Power inverter (DC -> AC), logic inverter a = !b, ...What do you want to build? Microchip has MANY power related app notes, especially for motor drives.Google might help, I found this:https://www.instructables.com/id/pure-sine-wave-inverter-using-pic-microcontroller-1/Search for 'using PIC for power inverter'.
Need a compact MOSFET driver  - Page 1
Forum section: electronics / beginners

author: muthukural001
author_rank: Regular Contributor
timestamp: January 03, 2019, 09:59:27 am
content: Hi,We need to design a printer head driver with 64 output channels in which each channel should be able to source max of 400mA, 40V. Our plan is to implement digital logic like shift register and Latch in FPGA and design 64 output channels which require a lot of Mosfet. Right now, we are looking for chip solution for 64 output channels. Attached is the single output channel circuit which provides 200-400mA, VH -40V, the same has to reproduce for other 63 output channel. Using individual MOSFET is not the right solution as it will increase the board size. As of now, I have found that MAX14912/MAX14913 which supports 8-channels and TLE94110EL which support 10-channels. But, the big concern with these chips is their size as I need to put 8 drivers to make 64 output channels. So, if anyone has come across a driver that will suit for our application, please suggest...Thanks,Muthu

author: Jwillis
author_rank: Super Contributor
timestamp: January 03, 2019, 11:04:27 am
content: Not sure but would this work ? It has 12 gate drivers.https://www.mouser.com/datasheet/2/302/MC33816-1126557.pdfwould only need 5 of those for 64 channelsA shot in the dark but you could try to adapt a 32 channel LED driver like this onehttps://www.analog.com/media/en/technical-documentation/data-sheets/3746fa.pdfIt would only require 2 for 64 channels.

author: hli
author_rank: Frequent Contributor
timestamp: January 03, 2019, 07:28:44 pm
content: What about single drivers? E.g. theMIC4414(from Microchip) comes in QFN and is only 1.2x1.2mm. Place it near the FET and it will basically vanish.

author: muthukural001
author_rank: Regular Contributor
timestamp: January 04, 2019, 09:06:36 am
content: Hi,Something is misunderstood, may be, it is with the term "MOSFET driver" that I have used. I don't want a driver to drive the gate of a MOSFET rather I need a driver which already includes MOSFETs to drive the load. I want one with 64 channel output in which each channel should source/sink max 500mA.Thanks,Muthu

author: spec
author_rank: Frequent Contributor
timestamp: January 04, 2019, 11:18:30 am
content: Quote from: muthukural001 on January 04, 2019, 09:06:36 amHi muthukural001Would it be possible with the print head wiring to have an 8 x 8 switching matrix? That way you would only need 2 x 8 way driver chips.

author: hli
author_rank: Frequent Contributor
timestamp: January 04, 2019, 10:41:54 pm
content: Well, the MIC4414 can deliver up to 1.5A. But with 3.5ohm resistance it might be a thermal problem - depending on the expected duty cycle. I think it will be a stretch to find something that can drive more than 8 lines at 500mA each. Even that setup would need to handle up to 4A throughout the whole chip, so the thermal issues will be interesting.I would try to look for e.g. double FETs with a low Rdson in a small package (or single ones - e.g. theNTLUS020N03Cis just 1.6x1.6mm, and 8 of them should be smaller than a SSOP20 package, and it drives 3A easily).
Need a little advice  - Page 1
Forum section: electronics / beginners

author: Jmh474
author_rank: Newbie
timestamp: May 14, 2021, 02:43:50 pm
content: Good afternoon all so I'm in the building a cnc router and I would like to use a program to control the speed of the spindle, now the spindle I have is controlled by a Potentiometer and the controller uses pwm iv brought a pwm to voltage converter.Dose anyone have any ideas on the best way to maybe get this to work?

author: beanflying
author_rank: Super Contributor
timestamp: May 14, 2021, 03:01:08 pm
content: Last time I saw someone put some numbers at the potentiometer on that combination it was in the order of 70-90V (from memory) so it is not that trivial to drive it from your CNC board.The nuts and bolts of it is it is possible but you will need a daughter board more than likely to take a PWM signal from your controller which will be set by GCode and then turn that into the appropriate voltage the power supply speaks.Unless someone has already done it we will be flying blind without a lot more information on your controller and the sorts of 'actual' numbers for the supply when you get it. Even then it remains non trivial so generally my understanding is of that conbination everyone just manually controls the speed.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 14, 2021, 03:14:43 pm
content: I don't know but most of the motor drive would take the speed command as 0-10VDC. So if your controller can output a 0-10V signal you can control the speed.

author: gamalot
author_rank: Super Contributor
timestamp: May 14, 2021, 03:22:43 pm
content: I did something similar a year ago. I disassembled my 48V SMPS so that I could draw the circuit diagram related to the output voltage adjustment, and then I made a PWM voltage generator to replace the external potentiometer. The output of the PWM should match the voltage range of the middle tap of the original potentiometer.

author: beanflying
author_rank: Super Contributor
timestamp: May 15, 2021, 01:02:51 am
content: Now it's not 1am and I have had a coffee. Have a good look at this and now I have had a relisten it was more an mains isolation issue than a voltage control issue. But well worth a look from 3 minutes on.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 15, 2021, 07:31:40 pm
content: I am curious that if you measure the voltage across the potentiiometer what would it be?
Need a low profile pin connector - Page 1
Forum section: electronics / beginners

author: Legion
author_rank: Frequent Contributor
timestamp: April 18, 2014, 06:05:40 pm
content: I've got an Arduino Uno with a 7 segment display shield attached to it. I'll be building an enclosure for it but I need to hook up wires to some of the female pin headers above and below the display. Thing is I need these connections to be as low profile as possible so the display can be flush with the front of the enclosure.I've tried looking on digikey but there are thousands of connectors and unfortunately I don't know what keywords to use to narrow my search. Suggestions?
Need a recommendation for a volume control knob please - Page 1
Forum section: electronics / beginners

author: bradleyheathhays
author_rank: Newbie
timestamp: March 23, 2017, 06:35:45 am
content: Complete novice here, and I'm trying to figure out what little volume control knob I need to splice into this wire here......in order to control the volume of the speaker on this 2 C cell powered alarm device. This is part of a 2 unit warning system where one box is the motion sensor, and the one pictured is the remote alarm. When viewed from the outside of the box (through the protective vents), the speaker appears to be made of copper foil.I have no clue what to look for even if the part was described to me, so would someone please be kind enough to provide a link for a small volume control knob I could splice in that would be appropriate for this application. Ideally I'd like to drill a small hole and mount it so the knob protrudes through to the outside of the plastic box.Thanks!

author: anishkgt
author_rank: Frequent Contributor
timestamp: March 23, 2017, 08:38:50 am
content: Probably and 10k potentiometer would do. A volume control is also called a potentiometer.Sent from my iPhone using Tapatalk

author: alsetalokin4017
author_rank: Super Contributor
timestamp: March 23, 2017, 09:22:30 am
content: Maybe so. The "speaker" looks to me like a piezoelectric element. Will a potentiometer (pot) give the desired result?If you want to try it, you'd wire it like this. The pot has three terminals. The middle one is the "wiper" and will connect to one side of the speaker element. The original two leads from the circuit board connect to the outer two terminals of the pot. The remaining lead from the speaker connects to one of the outer terminals of the pot.And of course you will want to put an actual "knob" onto the shaft of the pot once you have it installed and tested! There are a bazillion styles of knobs out there.

author: anishkgt
author_rank: Frequent Contributor
timestamp: March 23, 2017, 09:24:55 am
content: Quote from: alsetalokin4017 on March 23, 2017, 09:22:30 amWell, worth a try.Sent from my iPhone using Tapatalk

author: bradleyheathhays
author_rank: Newbie
timestamp: March 30, 2017, 03:30:49 am
content: Sorry so late getting back here...too many irons in the fire lately.But thanks for the advice. That sounds like exactly what I needed to hear. I'll prob get a 10k and 1k pot and wire them in and see what happens. If it doesn't work out I'll come on back and to describe how it went.
Need advice for a screen anti blue light filter from a good brand (Solved) - Page 1
Forum section: electronics / beginners

author: Logan
author_rank: Frequent Contributor
timestamp: November 29, 2020, 12:12:04 pm
content: Hello.I need to get some screen blue light blocker for several devices, but I cannot find any from a reliable brand, I searched some like 3M, Zeiss, etc, but found nothing.The devices screen size varying from 2-8 inches, bigger filter size is Okay because I can cut them by myself.I’ll accept those optical films not designed for screen(need to stick them by my self), I just don’t want to buy from those random brands that no one knows.Thanks.

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: November 30, 2020, 01:56:22 am
content: Assuming the devices can't be redshifted in software, have you considered something like aRosco Cinegel 3408? That'll give a colour temperature of about 3800 K, at a transparency of 73%. There is a redder option, the Cinegel 3411, which would give about 3200 K but you're down to 58% transparency at that point.

author: Logan
author_rank: Frequent Contributor
timestamp: November 30, 2020, 09:33:05 am
content: Thank you! Solved.
Need advice for flux (reflowing) - Page 1
Forum section: electronics / beginners

author: UberStrike88
author_rank: Regular Contributor
timestamp: January 19, 2015, 05:37:09 pm
content: Hi guys!I want to reflow the gpu on my laptop but i need flux to do that.So i had a look in my city and i found a guy that sells thishttp://www.kontaktchemie.com/KOC/KOCproductdetail.csp?product=FLUX%20SK%2010I can't speak german very well but i think it is flux right?And after I'm done can i use it for normal solder jobs too?I really want to know because i don't want to waste itIf it isn't good can you recommend me flux from ebay or a shop in the netherlands?And how much do i need to use?

author: Monkeh
author_rank: Super Contributor
timestamp: January 19, 2015, 09:11:00 pm
content: No, that's not flux, that's a solder-through varnish for storing unused boards.Reflowing your GPU is probably not going to do what you hope.

author: wraper
author_rank: Unknown
timestamp: January 19, 2015, 09:49:51 pm
content: What is your GPU? If Nvidia chip made before 2009, reflow could give it a bit more life, like week, maybe few months. But it won't repair the defect. That is a chip, not soldering fault.
Need advice or datasheet for industrial plasma display FPF8050 HRUC-001 - Page 1
Forum section: electronics / beginners

author: agent_power
author_rank: Regular Contributor
timestamp: April 22, 2025, 03:54:03 pm
content: Hi allI've got one of these displays from leftover stock, unused, but can't find anything useful on the net on how to drive it.It's an OKAYA Electric FPF8050HRUC-001, PCB marking N16B-5241-0001.Would be nice to find out what signals and voltages it needs to use it for somethingAny advice?

author: edavid
author_rank: Super Contributor
timestamp: April 22, 2025, 05:13:16 pm
content: There's a web page here:https://www.eldisplays.com/fpf8050hruc-001/That says:"For the FPF8050HRUC-001 pdf datasheet or detailed specifications of the FPF8050HRUC-001 or other Fujitsu items from Fujitsu, please email us at support@eldisplays.com or call us at 888-394-6077 at we'll be happy to provide one."I'd be surprised if they actually have it, but it's worth a try.

author: agent_power
author_rank: Regular Contributor
timestamp: April 27, 2025, 07:03:52 pm
content: I emailed them, but they didn't reply yet (and I doubt they ever will), so still looking for more information
Need advice - soldering station JBC RP 5100 on ebay for 100€ - Page 1
Forum section: electronics / beginners

author: DuanerD
author_rank: Newbie
timestamp: March 16, 2016, 02:17:36 pm
content: Hi everybody!I'm new here, wish i have the time to introduce myself a little more, but i'm at work and i just see a soldering station "JBC RP 5100" on ebay. The sell is over in 3hours, if i'm lucky i can have it for 100€ (110$). I'm in France, so it's very hard to find a cheap soldering station like hakko fx888, but i know nothing about old model from JBC... This one is a soldering/desoldering station. Do you think i should go for it? Any people here who know the station?Thanks!!

author: DuanerD
author_rank: Newbie
timestamp: March 16, 2016, 05:54:11 pm
content: I missed the station for 2 euros! Will try to find another oneEDIT: Find a PACE ST-25 for 100€. If you're interest, i can post some details about that station as soon as i receive and test it!
Need an explanation of this... please - Page 1
Forum section: electronics / beginners

author: PillaDoubleG
author_rank: Newbie
timestamp: February 21, 2024, 06:17:44 pm
content: This is the beginners section, so please dumb your answers down, if possible...In this video by styropyro (), he makes a "tesla coil" that produces a terrifying flame-like arc. The video is super interesting, I would definitely recommend it to everyone. In the end though, he mentions that the circuit oscillates at about 10mhz (if I remember correctly), but he also states that the output of the arc would instantly kill you.He then mentioned that a coil lacking isolation (no secondary coil) is deadly, no matter the frequency.From what I know, if the frequency of a circuit is above 20khz, it stops hurting, because the magnetic poles flip too fast for our nerves to detect them. Obviously there are other factors, but...Why does this arc kill? And how?Usually, a serious electric shock (if all of the conditions are right) would make your heart stop beating. So what would be the cause of death from this coil? Since it's high frequency, I don't see how the heart could be affected by it.I tried to word this as best as I can. Sorry if I forgot to mention something.Thanks in advance!!!

author: Andy Chee
author_rank: Super Contributor
timestamp: February 21, 2024, 06:29:42 pm
content: When he mentions lack of isolation, I'm going to guess that a step up auto transformer (b) is involved somewhere in his circuit topology:In which case, touching the arc would connect you directly to mains, and it is the mains current (superimposed on the arc) that kills you.But even if isolated, the high frequency high voltage can still cause harmful burns, which creates scar tissue within the flesh (ever see those wood burning videos using microwave oven transformers? Imagine that occurring within your flesh). If that scar tissue happens to take a path across your heart, it could also cause heart fibrillation.

author: MarkT
author_rank: Frequent Contributor
timestamp: February 21, 2024, 09:33:34 pm
content: Quote from: PillaDoubleG on February 21, 2024, 06:17:44 pmI think you mean 10MHz, 10mHz would be very very slow indeed, you'd be able to stroll out of the way!
Need assistance identifying components - Page 1
Forum section: electronics / beginners

author: Azapp1976
author_rank: Newbie
timestamp: December 22, 2019, 05:52:27 am
content: Hello EEVblogThis is my very first post on the EEVblog, I am a fairly new electronic hobbyist, I recently picked up some components at a local flea market,I believe that some of these components are diodes or resistors, however some are 2 band and there are no 2 band resistor calculators or color chartsthat I can find. I would like to find out the values of these components.If anyone could help me identify what these components are by looking at the photographs.thanks

author: Psi
author_rank: Super Contributor
timestamp: December 22, 2019, 06:13:51 am
content: Hard to be sure without measuring them because they are old/non-standard, but my guess is they're inductors.

author: WattsThat
author_rank: Frequent Contributor
timestamp: December 22, 2019, 06:16:16 am
content: Inductors, not resistors, based on body color and number of value bands. You can see the exposed wire on #3/4/5.1 & 2 are molded, 3/4/5 are open wound, #6 or “Diode-01” is definitely a blank form for hand wound inductors, typically RF chokes since the values will be in the low micro henry ranges and not usable for much else than RF applications. It was common back in the vacuum tube days to wind your own chokes on carbon comp resistors, similar to what you see in 3/4/5.
Need assistance to learn GPU repair - Page 1
Forum section: electronics / beginners

author: bensatrio8
author_rank: Newbie
timestamp: April 01, 2021, 04:37:02 pm
content: Hello everyone,I recently interested in repairing graphic cards, from diagnosing the problem and repairing them.But I have no basic in electronics, my only one resource is watching various gpu repair videos in youtube and try to understand blindly.this is one of them:https://youtu.be/2DyEoTP303IIs there any advice?Thank you

author: crossroad
author_rank: Contributor
timestamp: April 01, 2021, 04:46:08 pm
content: Yup, you should watch Louis Rossman's guide to repairing electronics that he originally made for new hires. It introduces enough electrical engineering theory from a repairmen's perspective and should be enough to get you started. It also includes pointers on how to navigate schematics and diagnose common issues like faulty parts and shorts.I'll look for the video and slides, will update this post when I find emHere it is!Short introduction to the guideThe actual guidehttps://docs.google.com/presentation/d/1PkeO_lC5WTPScSV3ZzEEjVuDWeQtL2eHK6jEcf7axA0/edit?usp=sharing

author: bensatrio8
author_rank: Newbie
timestamp: April 01, 2021, 04:50:52 pm
content: wow thank you very much,I maybe will also update this as my learning log for everyone in need.