hybridfree/eevblog-posts huggingface dataset:
On Semi D Type Reg Datasheet weirdness - Page 1
Forum section: electronics / beginners

author: BurnedResistor
author_rank: Regular Contributor
timestamp: July 12, 2017, 10:14:58 am
content: Hey All,Was looking into the MC14076B, a 4-Bit D-Type Register with Three-State Outputs.Under the function table it states in clear text that if either one or both of the output disable pins is high, this puts the outputs into HighZ.Yet, the logic diagram provided seems to contradict this:Both inputs are hooked into a nor gate, which in tern is connected to a buffer with what seems like a inverted input. Two inversion would then put a high on the buffers if there is a high present on the data disable inputs?Am I misreading something here? Is there an inconsistency in the data sheet?

author: vealmike
author_rank: Regular Contributor
timestamp: July 12, 2017, 11:53:46 am
content: Quote from: BurnedResistor on July 12, 2017, 10:14:58 amThey haven't told you what the function of that third pin on the output buffer is.To be clear, there's an output, an inverting input and a third pin.I agree it looks like an "Output Enable" OE. Given their use of the bobble to indicate an active low input, we can safely assume that it isn't OE_N. Can we rule out "Output Disable"?Personally I wouldn't sweat it. I'd believe the text / tables over the drawing.

author: BurnedResistor
author_rank: Regular Contributor
timestamp: July 12, 2017, 12:03:08 pm
content: Quote from: vealmike on July 12, 2017, 11:53:46 amHahahahaha. Alright. I just wanted a bit of a sanity check!

author: Ian.M
author_rank: Super Contributor
timestamp: July 12, 2017, 12:42:03 pm
content: Look at someone else's 4076 datasheet. e.g.http://www.ti.com/lit/gpn/cd4076bAs all manufacturers 4000 series are functionally equivalent (ignoring small differences in electrical specs), and the T.I. (ex Harris) datasheet has no such inverter in its diagram, its a good indication that whoever drafted that for OnSemi goofed.

author: BurnedResistor
author_rank: Regular Contributor
timestamp: July 12, 2017, 07:25:51 pm
content: Quote from: Ian.M on July 12, 2017, 12:42:03 pmGood Call!Any point in notifying On-Semi about this?

author: Ian.M
author_rank: Super Contributor
timestamp: July 12, 2017, 07:32:50 pm
content: Its the right thing to do, but unless you are an existing high volume customer of theirs with an assigned rep, don't hold your breath waiting for it to be revised.

author: Benta
author_rank: Super Contributor
timestamp: July 12, 2017, 08:27:15 pm
content: Don't see any reason to question the datasheet. You all seem to think that the line going from the inverter to the output buffers is an "output enable" but the datasheet doesn't say so.If that line is called an "output disable", the datasheet is 100% coherent.
On timer using Timer 555 - Page 1
Forum section: electronics / beginners

author: rahulb
author_rank: Contributor
timestamp: April 13, 2025, 06:11:23 pm
content: Hi Everyone,I am trying to make a timer which turns on after a duration.please check the image below:The time delay is made using capacitor C1 and R1.Concept is, when switch which is connected to Pin 2 of timer 555. The capacitor should start discharging through Pin 7. When the voltage goes below 2/3 voltage of VCC, the led should turn on.The problem is when I close the switch, the led immediately turn on and keep glowing.Does anyone know what I am doing wrong?thanks

author: Xena E
author_rank: Frequent Contributor
timestamp: April 13, 2025, 08:37:26 pm
content: Greetings rahulb.Download and read this book...https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.worldradiohistory.com/UK/Bernards-And-Babani/Babani/Babani-BP44-IC-555-Projects.pdf&ved=2ahUKEwiviqXO7dWMAxUZ_7sIHUbGMN4QFnoECCUQAQ&usg=AOvVaw2yQOfWdQ_saX7gAFGFqNkz
On-Wafer CV Measurements - Page 1
Forum section: electronics / beginners

author: fourierpwn
author_rank: Regular Contributor
timestamp: June 26, 2018, 10:08:33 pm
content: Hi all,I am wanting to do some on-wafer CV measurements. I have DC and GSG probes alongside a Keysight B1500A with MFCMU module (LCR meter module) installed. All of the documentation that I can find from Keysight makes use of an additional module; SCUU. This additional module is NOT essential, it simply converts the CV measurements from 4TP to 2TP (TP = terminal pair). For whatever reason, Keysight acknowledge that 4TP measurements are more accurate however they focus all of their documentation on the use of the SCUU and 2TP measurements.Regardless, I am new to CV measurements and am a bit confused about how to do things. Ideally, I would like to do Ciss, Coss and Crss measurements though this is, currently, beyond me. I think starting with Cgg measurements would be my best bet. Cgg - drain, source, bulk are shorted together and go to HC + HP terminals and gate goes to LC + LP, is this correct?My main concern is that the devices I am wanting to measure require GSG probes in order to eradicate self-oscillation, at least the larger devices do. By using GSG probes, I am unsure as to how one is to short D, S, and B together (B is not a problem as the devices have GSG/RF pads) or can I get away with using DC probes strictly for CV measurements?As I said, I am new to CV measurements so there is every chance that I have missed something crucial. Thus, any help would be greatly appreciated.
One driver for paralleled Mosfets? - Page 1
Forum section: electronics / beginners

author: Wrydog
author_rank: Contributor
timestamp: October 27, 2016, 09:23:43 pm
content: If you have two+ Fets in parallel, can you typically drive them with the same gate driver? What are the limiting factors?

author: danadak
author_rank: Super Contributor
timestamp: October 27, 2016, 09:58:03 pm
content: Its all about gate charge and available driver current and Pdiss and frequency.There is nothing preventing, proper design done, to drive more thanone MOSFET from the same driver. Problem is one MOSFET may havesignificant different Cg than another from different batches, so you needto look carefully at case where one fet lags another in the switching ofload.Especially load and safe area, thermal, considerations.Many welder designs parallel MOSFETs for cost considerations.There are many good ap notes out there from ST, IR, IXSYS..... on driverdesign considerations.Regards, Dana.
One of Dave's power supply kits - Page 1
Forum section: electronics / beginners

author: blatboy
author_rank: Unknown
timestamp: October 28, 2013, 03:02:52 pm
content: Hi. I'm new, but have been a lurker for a while.I've done some initial searches, but I can't seem to find the info for the kit for this power supply on Dave's bench. I'd like to build it methinks. Anyone have info? (Sorry if this question has been answered a zillion times...)Thanks!

author: Kirigozo
author_rank: Contributor
timestamp: October 28, 2013, 04:47:35 pm
content: Blatboy,The logo in the top left corner is Electronics Australia so it's probably 1970s vintage. Silicon Chip magazine bought all of the old EA stuff and now they just sit on it. Any more info will have to come from DJ himself.

author: blatboy
author_rank: Unknown
timestamp: October 28, 2013, 07:54:03 pm
content: Aha. Thanks for the heads up, Kirigozo.I'm always drawn to the "retro" stuff. Go fig. Mmmmm. Big VU. Melikes! *sigh*

author: johnboxall
author_rank: Unknown
timestamp: October 28, 2013, 09:39:34 pm
content: Every few years EA/Silicon Chip knocked out a bench power supply kit.This is the latest one from 2010, pretty sure Dave has one on the bench there:http://www.altronics.com.au/index.asp?area=item&id=K3218

author: EEVblog
author_rank: Unknown
timestamp: October 28, 2013, 09:47:45 pm
content: I don't recall the vintage off-hand, but at best it's 1980's.I don't have the one John posted, it's an older Altronics kit.

author: johnboxall
author_rank: Unknown
timestamp: October 29, 2013, 04:58:22 am
content: Here we go:

author: johnboxall
author_rank: Unknown
timestamp: October 29, 2013, 07:53:45 am
content: Quote from: wilfred on October 29, 2013, 06:11:22 amAh, looked very similar. Detailed in "Silicon Chip's Electronics Test Bench" compilation from 2000:

author: robbag
author_rank: Contributor
timestamp: October 29, 2013, 11:38:00 am
content: Thank you so much for posting the schematics. I built this power supply about 10 years ago but lost the schematics and couldn't remember how it worked when troubleshooting it recently.

author: blatboy
author_rank: Unknown
timestamp: October 31, 2013, 07:59:19 pm
content: Thanks so much for posting all this great info. I really appreciate it!
One-off flash reader / writer ? - Page 1
Forum section: electronics / beginners

author: Stonent
author_rank: Super Contributor
timestamp: January 05, 2016, 10:43:53 am
content: I've got a DVR / DVD Recorder made by LG (LRM-519) with a missing drive that I purchased for $14. The unit itself is based around an Intel Celeron 733, with i830 graphics and an ICH4 controller. Apparently it ran some Windows CE 5.0 version. LG will not assist me in getting any recovery media to restore the OS to a new drive. They said I'd have to send it into a service center to have the drive replaced with one of theirs for the tune of a few hundred dollars, so I thought I'd hack around with it a bit and see if I can convert it somehow to be a PC or at least bypass the signature checking so it will boot up some other OS.The bios is on a soldered PLCC SST49LF008B 8Mbit flash chip. It supports FWH, LPC, and apparently parallel flashing as well at 3V.I'd like to dump its contents, and possibly reprogram it, but don't have a programmer and don't want to have to buy one for this one time project.I've got some unused AVRs and PICs if there was an easy breadboardable project to read write this if anyone has some suggestions.

author: amyk
author_rank: Super Contributor
timestamp: January 05, 2016, 11:03:35 am
content: I can't find a datasheet for the B version but the one for the A version shows FWH protocol is a simple 4-bit bus with no minimum speed so a MCU should be able to bit-bang it.

author: Stonent
author_rank: Super Contributor
timestamp: January 05, 2016, 06:10:40 pm
content: Yeah B is the same as A but adds low pin count IO compatibility.QuoteThat part was a little deterring though.
one or morfe heatsinks for power transistord of an analog symmetric PSU - Page 1
Forum section: electronics / beginners

author: gibrancurtiss
author_rank: Newbie
timestamp: December 12, 2019, 11:16:12 am
content: Hello guys.I have a little analog symmetric PSU with -12V , +12V and +5V with linear regulators and I have to add a heatsink for the transistors. (TIP2955, TIP31, TIP3055)My questions :-may I add ONE heatsink for all transistors (even with regulators for positive and negative rails) ?-if the transistors back could not share the same heatsink (avoid shorting) , is really save adding a mica or silicon pad to isolate their electrical conductivity ?-where in the datasheet I can have the information what is the "leg" connected to the plate on transistor´s back?Thank you !!!

author: David Hess
author_rank: Super Contributor
timestamp: December 12, 2019, 12:23:25 pm
content: Quote from: gibrancurtiss on December 12, 2019, 11:16:12 amYes, that is very important if the metal tabs are not at the same potential which will usually be the case.QuoteThe pinout diagram should indicate it however for TO-220 and similar packages, it is always the center lead as far as I know.
one proof why trying to emphasize your gender is not a good idea... - Page 1
Forum section: electronics / beginners

author: SeanB
author_rank: Super Contributor
timestamp: December 23, 2015, 11:53:51 am
content: Somehow i doubt gender actually is an issue here, just stupidity.

author: grumpydoc
author_rank: Super Contributor
timestamp: December 23, 2015, 12:01:45 pm
content: The wire that he hit looks pretty dodgy actually.
One short pulse switch needed - Page 1
Forum section: electronics / beginners

author: charles713
author_rank: Newbie
timestamp: September 02, 2019, 01:30:40 pm
content: Hello Everyone, I have a 12V motion detection switch, a 12V power supply and 12V buzzer that I want to buzz shortly (0.5 to 1.0s) once the motion is detected. What should I look for and use as one short pulse switch?,relay? I have no idea about this stuff. I am familiar with basics only. Will appreciate your advice. Thanks!

author: GerryR
author_rank: Frequent Contributor
timestamp: September 02, 2019, 08:40:22 pm
content: You can buy a programmable Timing Relay, and set it up as a one-shot for the time required. Schneider Electric / Magnecraft makes one, 822TD-10H/UNI from Newark or Allied Electronics will do what you want done. You can probably download the spec sheet to see how it operates.

author: Zero999
author_rank: Super Contributor
timestamp: September 02, 2019, 09:08:12 pm
content: The classic is a monostable, typically a 555 timer.https://www.electronics-tutorials.ws/waveforms/555_timer.html

author: charles713
author_rank: Newbie
timestamp: September 03, 2019, 09:35:14 am
content: Thank you, a "timing relay" was what I was looking for. There are ready to connect inexpensive ones on eBay or Aliexpress, so I am good now.
One shot circuit - missing values... - Page 1
Forum section: electronics / beginners

author: gildasd
author_rank: Frequent Contributor
timestamp: November 25, 2014, 06:51:33 pm
content: I am breadboarding this circuit, but I have not idea what values I have to use for the resistors...The two transistors are BC547... And I've only got 2 left... Noob, I know.I have 100, 220, 470, 1k, 4.7k, 10k, 22k 100k and 1MOhm resistors...

author: Zero999
author_rank: Super Contributor
timestamp: November 25, 2014, 07:10:56 pm
content: The values depend on the time delay and desired current through the LEDs.There's a good article about how it works and what component values to use on Wikipedia.http://en.wikipedia.org/wiki/MultivibratorAs it's being powered off 12V, one of the transistors needs to have a diode connected in series with its base or emitter, to protect it from the negative voltage when the capacitor discharges, as a typical base-emitter junction is rated for no more than -5V.

author: gildasd
author_rank: Frequent Contributor
timestamp: November 25, 2014, 07:16:08 pm
content: I have 2 leds that act as diodes. They are standard green fare... 2V drop.As a side note, me UNI-T UT61B drives the led sufficiently to get them to light up

author: Zero999
author_rank: Super Contributor
timestamp: November 25, 2014, 07:18:59 pm
content: Then if you don't have access to a datasheet for the LEDs, aim for a forward current of between 10mA and 20mA.

author: gildasd
author_rank: Frequent Contributor
timestamp: November 25, 2014, 07:21:40 pm
content: Yeah that's correct. I limit the supply to 30mA anyhow...The delay is not important, just that the leds switch from one side to the other.

author: Zero999
author_rank: Super Contributor
timestamp: November 26, 2014, 01:29:13 pm
content: The calculations are fairly straightforward. How about suggesting some values, adding them to the schematic and posting it here? Then we can check.If you don't need a time delay then why not use a simpler circuit without any timing resistors of capacitors? Configure the transistors as a simple logic inverter.

author: gildasd
author_rank: Frequent Contributor
timestamp: November 26, 2014, 08:37:22 pm
content: Because we (in electronics lab class) wanted a delay in LED1 caused by the discharge of C1... Just to visualise the cap discharging.Anyhow, did not calculate, but started with high values going down until the darn thing worked:R1; 470R2; 470R4; 4.7KR5; 10KNo more BC547 were damagedIs there a rule to making breadboarding faster? Do you start from one end, the middle?
One-wire TMEX support for EEPROM function to read  blocks is limited    - Page 1
Forum section: electronics / beginners

author: basantab
author_rank: Contributor
timestamp: February 11, 2020, 05:30:01 pm
content: Modified and found solution:Ok, I was unclear about the read write process and hence confusion. It is possible to read larger memory by using different start address to read and read in chunks of 1023 or any other size multiple times. Remember to reset in between multiple reads.Hello,I am, trying to read and write EEPROM (DS28EC0) using TMEX library support. There is function call called "TMBlockStream " that supports only 1023 byte of data which was fine for older memory with 4 Kb. but his DS28EC0 has 20KB and it looks like there is problem reading the whole (2,560 Kb) of memory.Is there any way out or anyone has experience regarding this ? It works fine if i want to read only 1023 byte of mem.Function call:https://files.maximintegrated.com/sia_bu/softdev/owdocs/Docs/TMEX/bloc0zou.htmlTMEX overview:https://files.maximintegrated.com/sia_bu/softdev/owdocs/Docs/TMEX/tmwi5ur7.htmlSample code for reference:Code://num_pgs is 80 for DS28EC0..//fill in the 0xFF's in the buf to use as a read bufferlen = (num_pgs * 32);for (i = 0; i < len; i++)buf = 0xFF;// perform the block to start the read and return is equal read byte length which is limited to 1023 byteif (TMBlockStream(session_handle,buf,len) == len)rt = 1;
Onkyo TX-NR717 erratic behaviour, AVR won't stay on - Page 1
Forum section: electronics / beginners

author: wookiee
author_rank: Newbie
timestamp: December 22, 2024, 06:45:06 pm
content: I have Onkyo TX-NR717 that started exhibiting rather erratic behaviour. It started to turn off at random and surprisingly come on again by itself – no remote or button input. At first it was just an annoyance but with time this behaviour was impossible to ignore as it became more frequent. The unit is about 13 years old.Service manual is attached.I opened the unit and took out the power supply board BAPS-1145. I checked that standby transformer coils have continuity 1-3, 5-6, 8-9 and 11-12 are ok. There are no visible signs of overheating, no capacitors are bulging. I checked capacitors on BAPS-1145 with ESR meter, all have proper values and low ESR matching the reference tables. After taking apart, the unit would not come on at all. Pressing the power button had no effect. I hooked up scope to pins 6 and 7 on JL9000A on BAPS-1145 and here is the result after pressing the power button. These are MPOWER and STPOWER signals. I can’t remember which one is which on the attached plot.So the signals MPOWER and STPOWER appeared momentarily and the unit stayed off. I decided to attempt to switch on the main transformer by applying 9V to pins 2,3 of the relay RL9101 to see what happens. When I did that, the unit turned on and stayed on even after removing the 9V from pins 2,3 of the relay RL9101. The unit stayed on until auto off (no input), I think it was after 30 mins of so.The interesting thing is that now the unit appears to operate (almost) normally. When I press the power button, MPOWER and STPOWER appear and stay up and the unit turns on. However there is more strange behaviour. It appears that function keys on the front panel have a been assigned wrong functions. What I mean is that to change to a desired source you need to press a button to the right of actual label. If you have labels TUNER, TV/CD, PHONO, you need to press TV/CD to get TUNER and you need to press PHONO to get TV/CD.Any ideas what is going on and what to look for?

author: m k
author_rank: Super Contributor
timestamp: December 28, 2024, 02:17:07 pm
content: MPOWER is directly from the MCU, so from its point of view something unusual happened.Maybe it changed to its default state, that is different from what it should be.
Online courses for troubleshooting/repair - Page 1
Forum section: electronics / beginners

author: Dmoff
author_rank: Newbie
timestamp: January 12, 2022, 08:05:53 pm
content: Been in the electronics field for about 5 years now, went through the navys electronic tech courses and electronic and physical calibration school. spent 3 years on a carrier in a cal lab. now working in a civilian cal lab that does alot of repair to component level. i have basic troubleshooting knowledge and of electronic theory. looking to expand on that and learn alot more. have my gi bill and dont mind paying out of pocket either. Thanks in advance.

author: Grandchuck
author_rank: Super Contributor
timestamp: January 12, 2022, 09:37:35 pm
content: Are there any community college programs near you?I realized you asked about on-line but wanted to mention CCs anyway. At one time some CCs did offer on-line courses.My preference would be in-class ... just me

author: sairfan1
author_rank: Frequent Contributor
timestamp: January 13, 2022, 10:35:38 pm
content: @Dmoff sorry i could not get it, are you offering your paid help/service for repair
Online Education Australia - Page 1
Forum section: electronics / beginners

author: Cujo
author_rank: Regular Contributor
timestamp: May 26, 2019, 05:41:16 am
content: Is there any degree or course that offers electronics as online/distance education in Australia ?

author: EEVblog
author_rank: Unknown
timestamp: May 26, 2019, 12:33:29 pm
content: https://www.open.edu.au/
online electronics courses - Page 1
Forum section: electronics / beginners

author: delta75
author_rank: Contributor
timestamp: July 22, 2012, 12:29:27 pm
content: Hi all,I have seen the thread about electronic courses online, but they are focusing on free courses which do not seem to offer a certificate, i have been googling so much i am going crazy, i have found mit are going to be offering free online courses with an certificate soon.does anybody else know of any preferably australian but not only australian online course in electronics ,for example through a university or tafe that will offer a certificate at the end.The main reason is that it would be easier to get a job if i had some credentials, not just my word that i know the material,I can only study onlinethanks for any helpdelta75

author: Simon
author_rank: Unknown
timestamp: July 22, 2012, 12:36:01 pm
content: It would help to state your location (which you can also put on your profile) so that we can better advise. Usually foreign certificates are not much help in your own country depending on where you get them.

author: delta75
author_rank: Contributor
timestamp: July 22, 2012, 12:50:24 pm
content: Sorry i will change profileI am from queensland in australia

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: July 22, 2012, 01:30:01 pm
content: I signed up for the MIT online classes , but I lost my internet , so it was too much of an issue going to Wifi locations .I was not necessarily chasing the Cert. but just the learning , mostly from a ham radio perspective and doing repair & building .John

author: vk6zgo
author_rank: Super Contributor
timestamp: July 22, 2012, 03:05:04 pm
content: Quote from: delta75 on July 22, 2012, 12:50:24 pmWhy can't you go to a physical course?If you live in a remote area,sometimes the School of Mines or someone like that has such courses.Usually TAFE in most States have online courses,as do some Unis.Another possibility is to join the armed forces!

author: SeanB
author_rank: Super Contributor
timestamp: July 22, 2012, 04:07:06 pm
content: I did, and saw a lot of the country doing so. Met lots of interesting people...............

author: delta75
author_rank: Contributor
timestamp: July 23, 2012, 12:21:20 am
content: I am unable to physically go to a school due to working full time.i tried night school but couldnt get to many classes in time because of distance and work commitment. If i wasnt paying off my unit i would quit and study fulltime
Online electronics vendors - Page 1
Forum section: electronics / beginners

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: November 25, 2015, 02:00:19 am
content: Hello againalmost finishing the theoretical part of my project and i am almost ready to start shopping for parts.But i am not sure where fromI usually buy components of ebay because there is free shipping for Greece and tayda electronics because they have a vast selection of parts and reasonable shipping chargesBut in my project i use the 74HC390 and i could not find a bunch of through hole chips from one vendor only smd ones.I need some online electronics vendor suggestions with low shipping costs (if not free then reasonable) because i cant use element 14 or digikey because the product cost would be around 10 dollars and i would have to pay 40 when the shipping charge is added.It would be nice to be one place where i can pick everything i need instead of just the ic. ( Like tayda)Anyway thank you for your suggestions in advance

author: retiredcaps
author_rank: Super Contributor
timestamp: November 25, 2015, 05:09:24 am
content: Quote from: ChrisGreece52 on November 25, 2015, 02:00:19 amWhy don't you ask tayda to get it for you? Most are very helpful with replies like this.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: November 25, 2015, 05:06:39 pm
content: I did not know that was possible thank you very much
Online searchable catalog of re-useable circuit designs? - Page 1
Forum section: electronics / beginners

author: Stephen Durr
author_rank: Contributor
timestamp: July 13, 2014, 02:02:22 am
content: In the software world they call these things "design patterns", and they are meant to prevent people from reinventing the wheel. For most applications there probably already exists a well-designed pattern that works out of the box or at least provides a good general foundation on which to build. Is there any such similar thing for electronic circuit designs? I think in the past there were paper books like "Encyclopedia of Electronic Circuits", etc., but after a time paper books become out-of-date or the printed designs become superseded by newer designs based on newer components and/or techniques. So I am wondering does such a thing exist on the web?

author: ivan747
author_rank: Super Contributor
timestamp: July 13, 2014, 02:34:19 am
content: Usually this is the functionality of integrated circuits. But also, you can find common circuit blocks in app notes from the different component manufacturers.
Online tutorials (in a somewhat academic style) - Page 1
Forum section: electronics / beginners

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 29, 2015, 11:01:14 pm
content: FYI:http://mysite.du.edu/~etuttle/electron/elecindx.htmThis place has been around for a long time, he's got a lot of stuff across his website (from electronics to chemistry, physics, railroads and more..).Tim

author: houkensjtu
author_rank: Contributor
timestamp: May 30, 2015, 12:32:05 am
content: I love this site!It produces more insight into the fundamental of electronics than "the art of electronics". Of course the art of electronics is still fine for full of practical examples, I think this site is more suitable for noob like me

author: ez24
author_rank: Super Contributor
timestamp: May 30, 2015, 05:12:54 am
content: https://www.youtube.com/user/nptelhrdalmost unlimited almost 1 hour videos on everything an university teaches, it would take 4 years to watch them all

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 30, 2015, 05:55:27 am
content: And another rather good website (more practical and somewhat less academic) is...http://www.epanorama.net/
On/on vs On/(on) - Page 1
Forum section: electronics / beginners

author: iampoor
author_rank: Frequent Contributor
timestamp: January 22, 2014, 11:01:16 am
content: Whats the difference between an On - (On) switch and an On - On switch? Or an On - Off and On - (off) switch?I feel like a dumbo for not understanding this!

author: David_AVD
author_rank: Super Contributor
timestamp: January 22, 2014, 11:06:02 am
content: on-off - single throw (2 terminals per pole)on-on = double throw (3 terminals per pole)on-off-on = double throw (3 terminals per pole) but with a centre position where neither side is connected

author: Psi
author_rank: Super Contributor
timestamp: January 22, 2014, 11:10:13 am
content: i cant think of any reason for the brackets around the 2nd on.So both of those are probably exactly the same.Edit: Unless the brackets are some really weird way to imply an inverted contact (NO vs NC) etc, but i've never seen it written like that before

author: Andy Watson
author_rank: Super Contributor
timestamp: January 22, 2014, 11:16:26 am
content: Quote from: David_AVD on January 22, 2014, 11:06:02 amAgreed. I would guess that the brackets indicate the switch is biased, i.e. spring loaded for momentary action.

author: Psi
author_rank: Super Contributor
timestamp: January 22, 2014, 11:17:21 am
content: oh, true.Yeah, momentary would make sense for the bracket meaningCan't believe i didnt think of that.

author: Monkeh
author_rank: Super Contributor
timestamp: January 22, 2014, 01:06:58 pm
content: Brackets indeed indicate a momentary position.

author: MLXXXp
author_rank: Frequent Contributor
timestamp: January 22, 2014, 02:26:29 pm
content: Quote from: David_AVD on January 22, 2014, 11:06:02 amI've also seen on-on switches, without a centre off, specified as on-none-on.

author: fcb
author_rank: Super Contributor
timestamp: January 22, 2014, 05:17:54 pm
content: As Andy Watson said. The brackets indicate that is spring loaded.e.g. (on)-off-(on) would indicate centre off bias.
OOO a question about ordering parts digikey USA ship to within USA - Page 1
Forum section: electronics / beginners

author: 3roomlab
author_rank: Frequent Contributor
timestamp: January 03, 2016, 02:28:18 pm
content: i have a noob question, about ordering some tiny SMD SOT23 about 20 pc. to ship to an address in beaverton OR 97008.i cant seem to be able to get digikey to estimate a shipping price.if anyone out there has ordered similar sized parts, what did you pay to ship within USA generally?more expensive than mouser? TME?

author: 3roomlab
author_rank: Frequent Contributor
timestamp: January 03, 2016, 02:38:29 pm
content: yes i ordered from mouser, i used USPS priority (iirc 6.99?), their web page was straight about what the shipping is.digikey couldnt give an answer even by talking to their online customer service so i thought maybe someone here might know something about their ball park shipping charges.wanted to give digikey a try if the shipping is cheap

author: 3roomlab
author_rank: Frequent Contributor
timestamp: January 03, 2016, 02:56:50 pm
content: ah i see. thanks for the help

author: john_p_wi
author_rank: Regular Contributor
timestamp: January 04, 2016, 06:00:25 pm
content: Enter your zip here:http://www.digikey.com/ordering/shipping/shipcostestimatorLooks like an 8 oz USPS first class mailing for $3.54I have used this with no problem, as well as the Mouser USPS shipping.

author: 3roomlab
author_rank: Frequent Contributor
timestamp: January 05, 2016, 12:41:51 am
content: aha thanks john
OP-Amp analog Subtractor - Page 1
Forum section: electronics / beginners

author: Cali-Sam
author_rank: Contributor
timestamp: January 05, 2016, 06:20:35 am
content: I am trying to incorporate an Op-Amp subtractor into a project. ( Op Amp Circuit attached)I am applying about 2.5v into V1 and V2, therefore I am expecting a Vout value close to Zero. I know that I cant get exactly Zero due to opamp offsetinstead, I'm getting about 700 millivolt or so at Vout.Node A and Node B are not equal, as I would expect if negative feedback is working.Thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 05, 2016, 08:18:12 am
content: What op-amp are you simulating?I don't know Digikey's schematic tools, but it doesn't look like a theoretical (three terminal) op-amp model, rather, one that has the output constrained within the power supply limits. Check the datasheet for V_OL (output voltage low / saturation limit).Tim

author: tszaboo
author_rank: Super Contributor
timestamp: January 05, 2016, 09:26:04 am
content: 700mV, so your opamp is not rail to rail output. If you want 0V, use an opamp with dual rail. Meaning, connect it to -5V;+5V or -1V;+5V or -12V;+12V or something like that. Even with a true rail to rail opamp, you will never get 0V (unless you do some dirty analog tricks).

author: natbuk
author_rank: Contributor
timestamp: January 05, 2016, 01:15:46 pm
content: An alternative to running dual rail would be to move the 'ground' reference from the bottom of the non-inverting input resistor and make this, say your voltage rail /2 or 2.5V. Then you would have an output whose output was V1-V2+2.5. It's usual when using single-rail circuits to assume some kind of mid-point (such as half-rail) as a reference instead of ground. You will need to make that reference 'stiff' enough, depending on your resistor values, - can use capacitor and resistors if you need only AC subtraction, but otherwise, might need another amp, or some other way to make low-ish impedance. If source impedance is known, though, you can just choose some resistor dividers carefully.nat

author: TimFox
author_rank: Super Contributor
timestamp: January 05, 2016, 02:51:53 pm
content: With a single-ended positive supply, the output cannot go below zero, therefore cannot go to zero.(There are extraordinary exceptions, with some op amps that include booster circuitry to develop a negative voltage, but they are very rare.)If you need to go to zero, you should have at least some negative supply voltage--read the data sheet to see how close to the negative rail the output can swing.
Op amp based projects suggestion - Page 1
Forum section: electronics / beginners

author: MrOmnos
author_rank: Frequent Contributor
timestamp: November 25, 2015, 01:16:38 am
content: So, we were taught op-amps last semester. I understood the theory quite well and I did great in the tests. I didn't touch the books in the summer holidays and after 2 months it seems I have forgotten most of the theory. So, I thought best way to revise and memorize the theory is to do some projects. Please suggest some cool projects based on Op-amps which will require me to revisit the theory and do the calculations. I learn better by doing things.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: November 25, 2015, 02:10:05 am
content: Hey i found not long ago this sine wave generator using op ampshttp://www.play-hookey.com/analog/generators/sine_wave_generator.htmlyou can get a dual one and build it it does not take much time and its a good project for starting using op amps.You could also build a comparatorhttp://www.circuitstoday.com/voltage-comparatorbut as i was suggested in this right forum you better buy a real comparator if you are going to use it for a projectHope i helped you

author: TerminalJack505
author_rank: Super Contributor
timestamp: November 25, 2015, 02:54:28 am
content: Grab a copy ofthis PDFto get some inspiration.Some other ideas:Constant current source.Constant current sink (Dave's dummy load, for example.)Voltage regulator.PWM generator (better to use comparators, though.)

author: Lightages
author_rank: Unknown
timestamp: November 25, 2015, 03:52:59 am
content: Build a headphone amp as a starter. Then maybe a VLF radio receiver and listen to some weird signals. Try designing a microphone amp. So many things to try.....

author: AlxDroidDev
author_rank: Frequent Contributor
timestamp: November 25, 2015, 04:54:56 am
content: Quote from: TerminalJack505 on November 25, 2015, 02:54:28 amThat is one great source of info on Op Amp projects. Thank for that.

author: Synthetase
author_rank: Regular Contributor
timestamp: November 25, 2015, 06:58:58 am
content: Plenty of themhere(although most are to do with audio).I recommend buildingthisas it's an incredibly useful piece of kit for easily playing around with opamp circuit ideas.
Op-amp basic circuit help - Page 1
Forum section: electronics / beginners

author: Gazmon
author_rank: Regular Contributor
timestamp: March 05, 2019, 08:07:14 pm
content: Hi all,I’m just getting into electronics properly, I would like to build some op-amp circuits to get me going again, could anyone direct me to a site or info that gives basic to intermediate circuits I can build please practically on a bread board and then test with an oscilloscopeMany thanksGazmon

author: rstofer
author_rank: Super Contributor
timestamp: March 05, 2019, 08:27:09 pm
content: If you haven't already seen them, here are some good videos:Google for 'eevblog op amp' and 'w2aew op amp' for more...

author: dave3533
author_rank: Contributor
timestamp: March 06, 2019, 02:31:50 am
content: Another recommendation is to look at whitepapers from some of the big name semiconductor manufacturers. Texas Instruments has some great whitepapers on op amps (first Google result: HANDBOOK OF OPERATIONAL AMPLIFIER APPLICATIONS).

author: Audioguru
author_rank: Super Contributor
timestamp: March 06, 2019, 02:51:00 am
content: An opamp circuit built with a tangled mess of wires all over the place on a solderless breadboard will probably pickup interference by the wires and the capacitance between all the intermittent rows of contacts will cause oscillation.

author: rstofer
author_rank: Super Contributor
timestamp: March 06, 2019, 04:03:07 am
content: There are many evaluation boards but they aren't always inexpensive.Here is a board for a quad op amp in TSSOP package. Look at all the external circuit capability. You can solder in resistors and capacitors however you want.It has the advantage of being less susceptible to noise. It has the disadvantage of not using plugable connections.Go to Mouser.com and search for:EVAL-PRAOPAMP-4RUZNone of the links I tried worked properly.

author: jonroger
author_rank: Regular Contributor
timestamp: March 06, 2019, 05:48:13 pm
content: I also recommend that you learn to use LTspice. You can try things quite quickly.

author: Audioguru
author_rank: Super Contributor
timestamp: March 06, 2019, 08:02:38 pm
content: Quote from: rstofer on March 06, 2019, 04:03:07 amYour Mouser link goes to a page listing 4.4 million components.

author: Zenith
author_rank: Frequent Contributor
timestamp: March 06, 2019, 08:32:41 pm
content: Try this little book. Out of print but you can get them for £2 or so.https://www.amazon.co.uk/How-Use-Operational-Amplifiers-BP/dp/0859340635/ref=la_B0034Q5A5C_1_1?s=books&ie=UTF8&qid=1551902581&sr=1-1Basic amplifier configurations, oscillators, filters. Most of it's based on the 741. It gives pretty good explanations and waveforms. He recommends stripboard but I think a lot could be done with a breadboard, especially if you stick to a 741.

author: Gazmon
author_rank: Regular Contributor
timestamp: March 06, 2019, 08:36:52 pm
content: Some great information above thanks all 👍👍

author: rstofer
author_rank: Super Contributor
timestamp: March 07, 2019, 12:27:49 am
content: Quote from: Audioguru on March 06, 2019, 08:02:38 pmIt does indeed! I modified the post to suggest just searching Mouser for:EVAL-PRAOPAMP-4RUZ
Op amp circuit DC offset removal - Page 1
Forum section: electronics / beginners

author: crypton
author_rank: Contributor
timestamp: October 01, 2017, 11:53:45 am
content: Heya all!Im sorry if this has been discussed somewhere, but i haven't been able to precisely keyword my problem (If anyone knows a good search term, please, do tell).So i'm doing some more in-depth op-amp stuff than I've used to.This is my specific op-amp circuit:not sure how to embed attachment pictures...See attachment pictureThe circuit basically is like a variable PWM, depending on the input signal. I need PWM from both periods of the input signal around the set threshold (so I've created positive and negative threshold simultaneously).I get around 800mV offset (green and blue lines) at the final comparator 'switches', which I want to be at 0V when at rest. Any ideas what should I do ?I've messed around adding some negative feedbacks (makes the transitions slow though :S ) and trying differential op-amp modes, but maybe I'm doing it wrong...OR maybe there's some better circuits to achieve this behaviour (but this is what I came up myself though).(there can be more issues, when i want to build it up in real life - decoupling, actual resistor sizes etc, but these would be left for another topic I guess.)

author: orolo
author_rank: Frequent Contributor
timestamp: October 01, 2017, 12:29:36 pm
content: Look for "DC output voltage swing" in thedatasheet. For a 5V supply, the output of the AD8039 goes from 0.9 to 4.1V, not reaching ground. For a 2.5V supply as in your case (note that minimum supply is 3V according to datasheet) it's in that zone. If you want an op-amp whose output reaches the negative rail, look for a single supply op amp. An LM358 would work in your circuit (as long as the frequency doesn't go much higher than a few kHz), save again for the 2.5V supply again.

author: Ian.M
author_rank: Super Contributor
timestamp: October 01, 2017, 01:31:20 pm
content: That's what OPAMPs do when you run them open loop. In real life, most OPAMP outputs will probably slam to one of the rails even if you directly tie both inputs together and bias them to half supply.The AD8038/9 is a special case - its optimised for applications like buffering analog video with a closed loop gain of x1 or x2, and is only specced for operation at loop gains upto x10. The open loop gain is 70dB, which is a bit over 3.1V/mV (compare with uA741 at 200V/mV) so the output may not rail. However the typical input offset voltage of +/-0.5mV means you'll probably get anything up to about +/-1.5V offset at the output and worst case input offset of +/-3mV could give you +/-9.5V offset at the output.Also Vin goes below ground and your AD8038 chips are powered between +v and ground so you are exceeding their absolute maximum ratings and will probably destroy them. If you want a comparator with a ground referenced output, use one with an output ground pin, not an OPAMP!
OP Amp circuit - LP Differential Offset amplifier/filter? - Page 1
Forum section: electronics / beginners

author: hitech95
author_rank: Regular Contributor
timestamp: January 12, 2016, 01:05:42 am
content: Hi, I'm doing the reverse engineering of a cheap Chinese Bluetooth board ... I found that it use (partially)this scheme, the values are not the same. the gain (Rf / R) is about 2.I do not understand the configuration of this circuit, should be differential but there is also a LP filter on the feedback and an offset of Vcc / 2.I do not understand why there are the capacitors: "C3" and "C12".Thanks, hitech95.

author: SebG
author_rank: Regular Contributor
timestamp: January 12, 2016, 02:31:23 pm
content: HI.The circuit basically is a differential amplifier with high frequency filtering (C9, C11, C3 and C12). The half voltage (Vcc/2) is necessary since the input goes through a dc blocking capacitor (on all 4 input signals) so you get both positive and negative voltages at IN+ and IN- and the Op-Amp is just powered from 5V to GND. The resistors divide the voltage and the 4.7uF (relatively large) capacitor acts as a voltage source so the op-amp output would be half Vcc for no (0V differential) input. The small (33pF) capacitors allow high frequencies to be effectively grounded before reaching the Op-amps inputs (either to the Vcc/2 source or Op-amp output which acts as a V source). Then the output is also dc decoupled.Without the Vcc/2 bias the op-amp would cut off the negative part of the signal like a diode passing an AC signal.

author: hitech95
author_rank: Regular Contributor
timestamp: January 12, 2016, 07:30:07 pm
content: Quote from: SebG on January 12, 2016, 02:31:23 pmThen I understood right. I did not know that a differential amplifier could also be a filter. (In school I always made two step)Apparently the capacitor of the filter must be on both "feedbacks".The speech about Vcc / 2 I had guessed, I had asked such a thing a while ago.Thank you!
Op amp circuit problem - Page 1
Forum section: electronics / beginners

author: 1uk3
author_rank: Contributor
timestamp: January 10, 2016, 11:56:00 am
content: HiI have built an amplifier for small and short current pulses. The second stage is CR-RC²-shaper. It works quite well but i have noticed some (for me) weird behaviorThe Problem:As soon as i connect T1 ( 1.5m RG59/U 75?), i get a -2V offset at the output. The other end of the cable is open! Terminating it with 75? doesn't change anythingI can fix it by connecting a scope probe at TP1 and the offset disappears, even if the probe is not connected to the scope.The other weird thing is that the inverting input of U1 is also slightly negative (should be 0V right?)All op amps are LMH6682 (datasheethttp://www.farnell.com/datasheets/51551.pdf)D1 and D2: BAV99What I've tried:First i thought it is a bad solder joint, and the force of probe helps to make good contact.Then i replaced the probe with a 1M? and a few pF. Didn't work. I tried different values and either get no effect or oscillations.The supply rails are stable. Checked each solder joint a million times.When connecting an "antenna" i would have expected noise or 50Hz at the output, but a DC offset?I have no idea what the else i could do, would be very grateful for every advice.Thank you!

author: dom0
author_rank: Super Contributor
timestamp: January 10, 2016, 12:00:20 pm
content: - Photo of your build- High speed amplifiers can oscillate with low amplitudes that might be hard to see when checking the output at several V/div, but even these low level oscillations can disrupt operation.I don't really understand what you are trying to do with the open cable on the input? Can you explain your application a bit more?

author: 1uk3
author_rank: Contributor
timestamp: January 11, 2016, 04:21:32 pm
content: Thanks for your replyCan't give you a photo because I'm not at home for a week now.What do you mean with small amplitudes? <10mV? I couldn't find anything with my scope (ac coupled 10mV/div)On the other end of the cable is a high impedance sensor, but the problems started as soon as i connected the cable.I want to measure the area of a short current pulse with a relatively slow ADC.The first amplifier integrates over the peak, the following stages stretch the pulse.V(n006) is the output.Yes i know that there are precision peak detector circuits but i want to try it this way.

author: 1uk3
author_rank: Contributor
timestamp: January 17, 2016, 06:14:14 pm
content: dom0: You were 100% rightVery stable oscillation at >300MHz. I can only guess frequency and amplitude because i only have a DS1054Z (100MHz, 1GSa/s)Works perfectly fine nowThank you very much!