hybridfree/eevblog-posts huggingface dataset:
Understanding load regulation - Page 1
Forum section: electronics / beginners

author: Rainer Dynszis
author_rank: Newbie
timestamp: January 13, 2020, 10:21:29 am
content: Hello,I am not sure whether I understand load regulation specs for PSUs correctly.I believe it means that, when it says "load regulation: 0.01% + 2 mV", I can expect an open circuit voltage of 10V to drop at most by 3 mV (== 0.01% from 10V + 2mV) under load.Is this correctly understood? (I am asking because my voltage drops farther than that.)Thanks.

author: GerryR
author_rank: Frequent Contributor
timestamp: January 13, 2020, 11:41:34 am
content: You are correct, but there are other specs that go along with that, like at what rated current is the load regulation stipulated, the ripple / noise in CV mode and ripple current in CC mode, recovery time from a 50% load change, etc. If in a series regulation mode, dual supply for example, load regulation will generally be higher. What supply are you talking about?

author: mvs
author_rank: Frequent Contributor
timestamp: January 13, 2020, 11:59:09 am
content: Quote from: Rainer Dynszis on January 13, 2020, 10:21:29 amYes in general... But do you measure voltage at PSU terminals or at the load? Connection wires do have some resistance and may spoil your results.

author: ArthurDent
author_rank: Super Contributor
timestamp: January 14, 2020, 12:21:16 am
content: I believe the above post has the answer to your question. It is important where and how you measure the voltage and the link below has a good description of how local and remote sensing works. Lower current demands and shorter lead length help with local sensing supplies but for high current and long lead length you may need a supply with remote sensing, or compensate for the losses by measuring the voltage at the load and increasing the output at the supply.https://community.keysight.com/community/keysight-blogs/general-electronics-measurement/blog/2018/01/25/remote-sensing-is-important-for-your-power-supply

author: Jwillis
author_rank: Super Contributor
timestamp: January 16, 2020, 10:34:17 am
content: Check your DMM . Is it a high impedance DMM or a low Impedance DMM. When checking the no load voltage you need to use a high impedance DMM .Typically 1M . Some DMM are low impedence ( as low as 3K ) . This can give incorrect readings when checking load regulation.
Understanding Maxim part numbers - Page 1
Forum section: electronics / beginners

author: sijmen
author_rank: Contributor
timestamp: August 02, 2021, 11:13:17 am
content: Hi,I'm looking at the MAX4820 datasheet at Mouser:https://au.mouser.com/datasheet/2/256/MAX4820-MAX4821-1019183.pdfThey have the part in a 20 pin TSSOP package, but with 2 part numbers (MAX4820EUP+ and the MAZ4820EUP+T) as shown on the Mouser page:https://au.mouser.com/Semiconductors/Power-Management-ICs/Gate-Drivers/_/N-41fcp?P=1z0z7by&Keyword=MAX4820&FS=True&bws=1The datasheet does not indicate what the additional T means on the second part. Am I right to think that they are the exact same part, but the T refers to part being packaged in Tape instead of a tube?Regards,Sijmen.

author: Nikan
author_rank: Regular Contributor
timestamp: August 02, 2021, 12:47:06 pm
content: Yes, they are identical. The only difference seems to be that the MAX4820EUP+ comes in a tube and the MAX4820EUP+T on a Reel/cut.But be carefull when ordering, the ETP+/ETP+T has another footprint.Best Regads

author: tooki
author_rank: Super Contributor
timestamp: August 02, 2021, 02:21:14 pm
content: Quote from: sijmen on August 02, 2021, 11:13:17 amMouser doesn’t link to it, but Maxim has a guide to their product naming:https://www.maximintegrated.com/en/design/packaging/package-information/maxim-naming-conventions.html

author: sijmen
author_rank: Contributor
timestamp: August 02, 2021, 11:19:38 pm
content: Quote from: tooki on August 02, 2021, 02:21:14 pmThank you tooki. That all makes a lot of sense now.Regards,Sijmen.
Understanding MCU pin specification - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: December 16, 2014, 06:04:15 am
content: 1. I am using STM8S003F3 whose datasheet I have attached.2. I have question understanding its parameters : Injection current & power on any pin from external source when MCU is powered off.3. Typically MCU have two diodes connected on pin so that whenever pin voltage exceed/lower 0.3V from supply they get turn on. Now we can place a resistor in between to limit the injection current.Case 1: When MCU is poweredE.g if I apply Vin = 7V external, then internal diode will turn on , so that internal pin circuit will see that voltage. If diode has .3V drop then voltage will 5.3V.Now to limit the current , I can place a resistor like 10K. It will always limit the current within Iinj(max) of pin.Now how much value can be Vin i.e what could be its max valueI guess it can't be 100V & if I limit the current then MCU will work pin by turning on its diode.There will be some breakdown voltage. Where it is mentioned in datasheet.Case 2: When MCU is unpowerede.g I am using uart or adc. Then even if MCU is unpowered. External sensor/uart will keep on giving some voltage on pin.E.g external uart keep tx pin high.So how to protect the MCU pin in this case when it is unpowered?Will limiting the current to Iinj(max) will save the pin?

author: Jeroen3
author_rank: Super Contributor
timestamp: December 16, 2014, 10:09:10 am
content: Instead of disconnecting Vdd, put the chip in power-down mode by software.Ignoring the note under the absolute maximum ratings,twice, isn't going to help you with your complaints if you get field failures.
understanding MOVs and surges - Page 1
Forum section: electronics / beginners

author: hsn93
author_rank: Regular Contributor
timestamp: November 18, 2020, 04:42:07 pm
content: hello,im trying to understand sizing MOV , or a TVS based on defined surge ..assume having the following conditions:MOV data:https://www.tdk-electronics.tdk.com/inf/70/db/var/SIOV_Leaded_StandarD.pdf- 8/20uS surge 4KV 2ohm impedancewould this mean there is maximum power of :-- i assume maximum power transfer happen if (load = source = 2ohm)-- peak power/current @4KV source impedance 2ohm load impedance 2ohm = 1000A peak current = 2,000,000 Watts ?-- 1 watt = 1 joule / second-- assume worst case just to ease calculations: IIR = 1KA * 1kA * 2ohm * 20uS = 40 Joules ?Q1:so does this mean the MOV has to be bigger than 40 joules ?i see the largest one here is B72220S0300K101 for (38VDC)Q2:which has power rating of 26J (2ms << if applied 2ms waveform?)Q3:what is the difference between Joule and Watts in the tables (Pmax) and (Wmax) provided by TDKactually im trying to show what is in my mind here .. but i feel its all crap and wrong .. what is the correct way of defining the joules or watts ?-------------------------------------------------------------i also see the derating graph on same document:Screenshot 2020-11-18 192832.png(92.97 kB. 810x730 - viewed 144 times.)Q4:i didnt understand what are the numbers for each lines .. ie (derating 1x line)

author: mag_therm
author_rank: Frequent Contributor
timestamp: November 18, 2020, 06:05:24 pm
content: search: "Varistor_design_examples" and a good application note will come up.
Understanding N76E003 startup file by Keil - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: July 21, 2018, 10:44:41 am
content: I am working on Nuvoton N76E003 MCU & using Keil C51 for this. Keil added a startup file. I have below problem in understanding it:1. Attached find the keil startup file.2. The datasheet of N76 says it has 256 bytes of Idata RAM. & 756 bytes of Xdata.But startup files on line 25 says:IDATALEN EQU 80H ; the length of IDATA memory in bytes.Is it an error?3. But line 45 saysIBPSTACKTOP EQU 0FFH+1 ; set top of stack to highest location+1.where stack is defined at top of RAM i.e 256 bytes.Or this startup uses 128 bytes as RAM & fix rest of remaining top 128 bytes as stack space?
Understanding op amp circuit - Page 1
Forum section: electronics / beginners

author: d4n13l
author_rank: Regular Contributor
timestamp: July 23, 2019, 11:48:05 pm
content: Hi,I'm starting with op amps, from the schematic, I get 0-1V from voltage divider, and I would expect to see the same voltage in the output of the op amp due to the negative feedback but it stays frozen at 1.9V no matter the +IN voltage. Could someone help me figure out why isn't it working?

author: rstofer
author_rank: Super Contributor
timestamp: July 24, 2019, 12:19:26 am
content: Check the data sheet. The op amp probably can’t work within a couple of volts of the rails.

author: Ultron81
author_rank: Contributor
timestamp: July 24, 2019, 01:40:47 am
content: Yeah, what he rstofer said. If you want the input to drop to 0, you either need to supply a negative supply voltage to the op amp, or use a single-supply op amp that can go to 0V like a LM358.

author: d4n13l
author_rank: Regular Contributor
timestamp: July 24, 2019, 01:59:16 am
content: It worked with the LM358, I didn't know that not all op-amps can be used like that. Thanks

author: nigelwright7557
author_rank: Frequent Contributor
timestamp: July 24, 2019, 03:17:22 am
content: Quote from: rstofer on July 24, 2019, 12:19:26 amTry a rail to rail op amp.Not all op amps work close to the rails.In fact some invert the output if close to the rails.

author: David Hess
author_rank: Super Contributor
timestamp: July 24, 2019, 03:30:21 am
content: The LM301 is a fabulous part for many reasons but those do not include input and output ranges which extend to the negative supply.Note that even if the input voltage was higher, that circuit still would not work as shown because the LM301 requires external compensation to be unity gain stable. Usually this would be a 33 picofarad capacitor between pins 1 and 8. The LM358 you tried has the compensation capacitor built in.

author: magic
author_rank: Super Contributor
timestamp: July 24, 2019, 08:32:39 am
content: Quote from: d4n13l on July 24, 2019, 01:59:16 amIt gets worse. With other parts like RC4558 and TL072, tying IN+ to ground makes OUT and IN- fly to the positive rail.Phase reversal also occurs in almost all JRC audio opamps, as they are variations of the same old 4558 topology. Probably many power amplifiers too, but you are unlikely to feed them signal which exceeds their negative supply rail and you are screwed anyway if you do.

author: rstofer
author_rank: Super Contributor
timestamp: July 24, 2019, 03:12:54 pm
content: w2aew has a video that shows this output problemAround 8 minutes in he shows output clamping.
Understanding potentiostat circuit - Page 1
Forum section: electronics / beginners

author: rookie
author_rank: Contributor
timestamp: August 13, 2018, 09:42:55 pm
content: Hello everyone,I am trying to understand the potentiostat circuit that is outlined in this attached figure. I am not sure why two resistors are required for the working of the op amp. They are usually of the same value (10k or 11k). I thought it was a differential amplifier, but it doesn't resemble one. May be it is? I am thoroughly confused at this point. Hopefully be someone can help me understand this circuit?

author: David Hess
author_rank: Super Contributor
timestamp: August 14, 2018, 02:58:55 pm
content: I wonder if the potentiostat was brought to your attention by recently watching the same video that I did.The resistors and capacitors implement external frequency compensation to prevent the operational amplifier from oscillating. Just one RC pair should be sufficient; I do not know why the schematic shows two.The operational amplifier maintains voltage on the CE electrode such that the voltage between the reference electrode and WE electrode is equal to the reference voltage at the non-inverting input.backare part of the external feedback
Understanding proximity testers - Page 1
Forum section: electronics / beginners

author: Seamus16
author_rank: Contributor
timestamp: October 16, 2016, 03:10:38 pm
content: I have an Extech 330 MM and amongst other things have been checking my various phone etc chargers and have noticed that the MM lights up on the low voltage side on some of the chargers. I have checked the continuity back to the mains pins and there is nothing shown.I am not clear why this is happening so could someone enlighten me please.

author: Connoiseur
author_rank: Regular Contributor
timestamp: October 16, 2016, 05:59:41 pm
content: It is due to Y capacitor which is connected across the primary and secondary of the high frequency transformer to provide a low impedance path dor the rf noise to ground via the mains.It has a very limited capacity, hence does not allow much mains frequency current to flow (you may feel pricking sensation on sensitive skin like back of hand or face but no shock). However NCV can be triggered because it detects electric fields, not current.

author: Seamus16
author_rank: Contributor
timestamp: October 16, 2016, 07:08:42 pm
content: Thanks - that is a great help and gives me a better understanding. There is so much 'less than good' chargers around that I get suspicious.

author: Brumby
author_rank: Unknown
timestamp: October 18, 2016, 06:50:49 am
content: Your caution will serve you well.There are so many chargers out there - and so many are sub-standard. A lot of the time they will behave - but if there are going to be any failures, it will likely be one of these ... and some of the failure modes are quite scary.
Understanding pyroelectric/PIR variants in TO-5 case - Page 1
Forum section: electronics / beginners

author: failalready
author_rank: Newbie
timestamp: June 19, 2023, 06:57:01 pm
content: Hi friends, new here. Refugee from Reddit.The short of it is I'm looking to replace the BS412 in my design with something that'll be in-stock ongoing.I had previously used the modules with the board and header attached (the kind you get on Amazon by searching "PIR"), but I came across the BS412 from Adafruit, and found I could use it as-is in my design, and it did the job, only taking up the space of a TO-5 package (https://www.adafruit.com/product/4666). They don't stock them anymore, and looking at the stock for sensors from this manufacturer (Senba) on Octopart, it's not looking like something I should plan around having access to in quantity.I bought a couple Zilog ZRE200GE components, but I think I'm stupid, because looking at the data sheets, the Senba PIRs refer to internal circuitry,where I'm guessing the ZRE200GE would need external components to function in a similar way,So, I guess, is it true that what is sold as a PIR in a TO-5 case can vary in this way in what is included within the package? If so, any recommendations for a replacement for the BS412, or advice on how I can search for a replacement more effectively?Thanks.

author: calmtron
author_rank: Regular Contributor
timestamp: June 20, 2023, 03:59:55 am
content: Look for sensors with integrated signal processing electronics.
Understanding schematics - Page 1
Forum section: electronics / beginners

author: per4manz
author_rank: Newbie
timestamp: March 17, 2019, 07:32:06 pm
content: I am new to reading schematics and had a couple of questions regarding an Apple schematic I am looking at:There are several capacitors marked with package size 402-2. I know what a 0402 package is. And I know this is still indicating an 0402 package. But what is the “-2” part of the package? I am assuming a specified height, but once again cannot find an actual package specified as such or even a reference online to such a designation.At the top of the schematic page for a back light circuit I see the following in the page notes: “BKLT:ENG - Stuffs 10.2 ohm series R for engineering builds. BKLT:PROD - Stuffs 0 ohm series R for production.” Several resistors on the schematic are marked as “BKLT:ENG “ @ 10.2 ohm resistance. However, since this is an actual production model, would I replace those with 0 ohm resistors if need be or stick strictly to the schematic designations?Any help would be greatly appreciated.

author: helius
author_rank: Super Contributor
timestamp: March 17, 2019, 08:39:01 pm
content: The series resistors would be used as current shunts for external monitoring of the current to the backlight. Attaching a voltmeter by tweezers to the resistor (or probes to suitable test points), and dividing the resulting voltage measurement by 10.2, yields the current. When product testing has been completed, there is no longer a need for these current shunts, so they are replaced with zero-ohm jumpers. Presumably, the circuit will work either way, if it uses a current-mode supply.I don't know the significance of the other question.

author: per4manz
author_rank: Newbie
timestamp: March 17, 2019, 10:15:50 pm
content: Thank you, Helius. That helps a lot as I was about to order resistors. So at this point I think I will be okay with 0 ohm resistors.And yes, the other question is odd since 99%+ of the resistors and capacitors are simply identified as 402. That's why that one is throwing me off.

author: per4manz
author_rank: Newbie
timestamp: March 18, 2019, 04:29:32 pm
content: One other question: am I correct in my assumption that I can ignore anything marked NOSTUFF?

author: helius
author_rank: Super Contributor
timestamp: March 18, 2019, 10:04:58 pm
content: "NOSTUFF" means literally "do not stuff this component": the pick-and-place machine ignores them and does not put them on the board. After assembly, the pads remain empty. Usually this is for alternative components or subcircuits that were designed but later removed for cost or EMC reasons. The word is still "stuff" because automated assembly was originally for thru-hole technology and the components were being stuffed into the holes.You can ignore them in the sense that they are not required. It can provide some insight into the circuit function, because the idea is that they would function if they were installed, possibly replacing another circuit element.

author: per4manz
author_rank: Newbie
timestamp: March 18, 2019, 10:20:15 pm
content: Your help is greatly appreciated!
Understanding scopemeter terms. - Page 1
Forum section: electronics / beginners

author: thermal
author_rank: Newbie
timestamp: July 26, 2013, 03:45:35 pm
content: Scopemeter, labscope, graphing multimeter, oscilloscope, are these all the same? What are the differences? Is one better than the other? Which should I use ,when & why?

author: c4757p
author_rank: Super Contributor
timestamp: July 26, 2013, 03:51:31 pm
content: I'm not really sure what a "lab scope" is, but a quick Google suggests it's something automotive-related?Scopemeter: combo oscilloscope and multimeter. Great when you need something to carry around, or you need to take floating measurements (it's not ground-referenced like a bench oscilloscope). Usually a bit of a pain to use and the specs aren't as good for a given price.Oscilloscope: The real McCoy. High bandwidth, high(er) accuracy, ground-referenced (can be good or bad), easy to use, sophisticated features, simple software interface capabilities, bulky and not portable. Old analog ones don't have as many software features (don't let that make you think they havenonebecause they're analog, the Tek 24XX series for instance had many), but they make up for that with their ability to double as a deadly weapon if you need to defend yourself.Graphing multimeter: Very high accuracy and precision (usually the full precision of the meter itself, while most oscilloscopes have 8-bit/256-level precision only). Very slow, only meant to plot long-term trends.
Understanding SSR behaviour - Page 1
Forum section: electronics / beginners

author: CountChocula
author_rank: Unknown
timestamp: July 01, 2023, 09:39:13 pm
content: Hello. I recently got my hands on a couple SSRs from Toshiba (modelTLP3553A); I have never used these kinds of components, and so I thought I'd have a play around.At DC, everything seems to work fine. If I apply a voltage through a resistor to pins 1 and 2, the relay allows a current to flow between pins 3 and 4 in either direction.With an AC signal (a simple 5VPP sine wave from my signal generator), however, things get pretty strange. Regardless of whether there isanythingconnected to pins 1 and 2, the waveform gets through from pin 3 to pin 4 without any problem (except that it seems to be capacitively coupled, so any DC offset goes away if there is no current on the LED. This happens even if I just connect the output of the generator directly to pin 3, and my 'scope probe to pin 4, with the grounds from both tied together, and it seems to be independent of frequency.I'm not sure what's going on—I'm sure I just don't understand how SSRs work, but I'm not quite sure where to look for an answer. Thanks!—CC

author: bdunham7
author_rank: Super Contributor
timestamp: July 01, 2023, 09:57:22 pm
content: There's some parasitic capacitance across the outputs so unless you have a lower impedance load, you'll see an output signal. Try connecting a 1K resistor from the output to ground and it should behave as you expect.

author: CountChocula
author_rank: Unknown
timestamp: July 01, 2023, 11:14:22 pm
content: Indeed, that does the trick—thank you!
Understanding Symbol? - Page 1
Forum section: electronics / beginners

author: ryanmills
author_rank: Unknown
timestamp: March 01, 2022, 02:08:15 am
content: Datasheet:https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electric%20Works%20PDFs/PhotoMOS%20hookup%20diagram.pdf(top of page 3)Bit confused by this example. Solid state relay, on the output it shows AC/DC with no polarity direction. If hooking it up for DC is there a correct direction for GND or does it not matter?

author: bob91343
author_rank: Super Contributor
timestamp: March 01, 2022, 05:00:29 am
content: I think it doesn't matter.

author: golden_labels
author_rank: Super Contributor
timestamp: March 01, 2022, 05:28:06 am
content: It doesn’t matter. If charge can flow in both directions, it can do that in either as AC or DC.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 01, 2022, 04:14:52 pm
content: RTFDS

author: golden_labels
author_rank: Super Contributor
timestamp: March 01, 2022, 09:42:28 pm
content: There is no description. There is an equivalent schematic provided, but it may be unclear to less experienced people that are used to seeing DC layouts with only one possible polarity.

author: ryanmills
author_rank: Unknown
timestamp: March 02, 2022, 02:17:52 am
content: Quote from: Terry Bites on March 01, 2022, 04:14:52 pmWhat do you think the f'ing image is from? What is that link under the image too? I will help you out, the image is from the datasheet.Not the highest amp output on this guy.

author: free_electron
author_rank: Super Contributor
timestamp: March 02, 2022, 03:23:37 am
content: Quote from: ryanmills on March 02, 2022, 02:17:52 amhis noise floor on the other hand is through the roof..the output of those photomos devices is bidirectional. There is no polarity. for all means and purposes they are a relay contact.

author: ryanmills
author_rank: Unknown
timestamp: March 03, 2022, 04:04:57 am
content: Quote from: free_electron on March 02, 2022, 03:23:37 amWell played.And thank you!

author: fourfathom
author_rank: Super Contributor
timestamp: March 03, 2022, 06:06:37 am
content: It's bidirectional, polarity on the output doesn't matter. I have used the single-channel version of this series for low-level AC signals and as a DC switch. Read the datasheet for on-resistance, off-leakage, voltage/current limits, etc.
Understanding , testing transformers  - Page 1
Forum section: electronics / beginners

author: Seaofdep
author_rank: Regular Contributor
timestamp: October 04, 2017, 07:03:57 am
content: Hi, I've been researching transformers and I can't seem to find anything about a particular issue I have came across. I'm posting here in hopes to get some help.Inverter board : transformer pin 5 voltage drop .I have tested all the transformers and they all have the same voltage while grounded , but I noticed one has a severe voltage drop on one of its pins when not grounded, which makes me believe a faulty transformer, what i would like to know is how and why do transformers have voltage drop fault , is it fixable and why do I get same voltage on all transformers pins while grounded ? Any help is much needed and appreciated thank youSent from my iPhone using Tapatalk

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 04, 2017, 12:57:28 pm
content: Uh... schematic?Tim

author: Seaofdep
author_rank: Regular Contributor
timestamp: October 04, 2017, 01:05:09 pm
content: I couldn't find one , but I'll post a pic of the inverter in a little bitSent from my iPhone using Tapatalk
Understanding the biased diode clipper - Page 1
Forum section: electronics / beginners

author: Aeternam
author_rank: Unknown
timestamp: November 30, 2016, 08:13:24 am
content: I'm having a hard time understanding how a biased diode clipping circit works.I think I understand what happens with D2 (ignoring D1 for the moment): on the positive portion of the AC signal (*) Vkathode > Vanode, so the diode does not conduct and we get the full signal at Vout. On the negative portion of the AC signal, Vkathode < Vanode so the diode conducts and since the output is parallel to D2 we read its operating voltage (0.6V) at Vout.Now we bring D1 into play. As long as the input signal is below V2 (5V in the example) the diode does not conduct, we read the input signal at Vout, so far so good. Here comes the part I don't understand: as soon as the input signal goes above 5V Vkathode < Vanode, so D1 starts to conduct. Say the input is at 10V. The simulation says the output should be at 5.6V. How does that work? Where do the other 5V go? Where does the +0.6V come from (it's the diode drop allright, but why is it present at Vout)?I'm sure the answer is obvious but I'm drawing blanks here(*) I should probably mention that in the example, the input signal is a -10V to 10V sine.

author: trophosphere
author_rank: Frequent Contributor
timestamp: November 30, 2016, 08:30:49 am
content: D1 starts to conduct at 5.6v (not 5v) because D1 has a Vf of 0.6v. When D1 conducts, the output becomes clamped at (ground + 5v source + 0.6v Vf of D1). The "extra voltage" is (in relative terms - actually current limited by the resistor) shunted to ground so that the output is now maintained at the point where D1 just about turns on.

author: xavier60
author_rank: Super Contributor
timestamp: November 30, 2016, 08:45:29 am
content: The clipping will be asymmetrical. Coupling capacitors should be placed in series with the input and output.
Power Supply EA Compensation Networks - Page 1
Forum section: electronics / beginners

author: Burning Circuits
author_rank: Contributor
timestamp: June 06, 2020, 11:18:12 am
content: Hi,someone can suggest me some good reading, to understand and design, the compensation networks of the error amplifiers?Thank you very much.

author: Wimberleytech
author_rank: Super Contributor
timestamp: June 06, 2020, 12:41:00 pm
content: Quote from: Burning Circuits on June 06, 2020, 11:18:12 amPlease be more specific

author: Burning Circuits
author_rank: Contributor
timestamp: June 06, 2020, 12:46:55 pm
content: Quote from: Wimberleytech on June 06, 2020, 12:41:00 pmSorry, you are rightIn the design of a power supply, both linear or switching, the frequency compensation of the op-amps that make the error amplifier(s) is needed through RC networkI ask if there is some good reading regarding this topic.

author: Wimberleytech
author_rank: Super Contributor
timestamp: June 06, 2020, 12:58:01 pm
content: Quote from: Burning Circuits on June 06, 2020, 12:46:55 pmExcellent. There are a number of SMPS gurus around here...you will get some responses, soon, I am sure.

author: rbola35618
author_rank: Frequent Contributor
timestamp: June 09, 2020, 01:58:04 pm
content: Here is a video I did where I explain how to model and set the loop compensation. I hope this helps.Robert

author: Burning Circuits
author_rank: Contributor
timestamp: July 06, 2020, 06:00:54 pm
content: Quote from: rbola35618 on June 09, 2020, 01:58:04 pmThank you very much!
Understanding the influence of a dc-dc booster in battery life - Page 1
Forum section: electronics / beginners

author: FBMinis
author_rank: Regular Contributor
timestamp: February 15, 2023, 04:28:46 pm
content: I am not sure what will make my 5V device work longer:- 4xAA alkaline (2400mAh each);- Same type of AA but in a 2S2P configuration with a voltage step-up module (blue one -https://www.aliexpress.com/item/1189492730.html)The load consumes 300mAh during 2min, then is cut from power for 58min.

author: wasedadoc
author_rank: Super Contributor
timestamp: February 15, 2023, 04:39:28 pm
content: Is your load happy with the 6 Volts that 4 cells in series can produce?The current supplied by each cell will be almost the same in each case. The current into the step up converter will be close to twice the current out. But it is coming from two pairs of cells in parallel instead of four cells in series.No step up converter is 100% efficient so loss there. OTOH the step up may still be able to give 5 Volts out when the cells are more discharged then when using 4 in series.

author: TomKatt
author_rank: Frequent Contributor
timestamp: February 15, 2023, 04:53:20 pm
content: Quote from: wasedadoc on February 15, 2023, 04:39:28 pmThat's an excellent point and likely immensely complicated to figure out other than through experimentation.

author: tunk
author_rank: Super Contributor
timestamp: February 15, 2023, 05:04:05 pm
content: For 4xAA, I guess it depends on what voltage range your device can run on:New alkalines are around 1.6V and fully discharged, they can go below 1V.If it e.g. cannot go below 5V, you will waste around half the capacity.And a step-up module may have some (significant) quiescent current.

author: FBMinis
author_rank: Regular Contributor
timestamp: February 15, 2023, 06:50:00 pm
content: Quote from: wasedadoc on February 15, 2023, 04:39:28 pmProbably safer with 3xAA

author: wasedadoc
author_rank: Super Contributor
timestamp: February 15, 2023, 06:57:05 pm
content: Quote from: FBMinis on February 15, 2023, 06:50:00 pmBut those will not give 5 Volts.

author: JeremyC
author_rank: Regular Contributor
timestamp: February 15, 2023, 07:06:24 pm
content: Quote from: FBMinis on February 15, 2023, 04:28:46 pmYou should consider “step up down” type of converter. Efficiency is in range of 95%.Below is link to an example:https://www.ebay.com/itm/384316104430?hash=item597b065eee:g:srMAAOSwQX9iBwDC&amdata=enc%3AAQAHAAAA8EJi%2FcgwI0knZTcPR8cxpVk%2BPXS8scNBjL8TMKX59T23ulTKV8%2BpTwN6NAy33TMZDBs6xbinGGAII%2BHdacYKF75o8L6JEm04rYmxIa9aojfD2peSwVc2vzdGHVbf7j17f8BYCioDUbUxE%2FzKrTQhZRXtH3mPieHEV%2F%2Bn8%2BLIOxsjBcPQofHVQ%2FlkmH04DlmQzNFZxtRAmJnwpyXV04Zqqs1mfdUjiGMRkRYLUaGqadgDPIzzeja8LLrr1TFAEy14%2Fj4Pp5SCdo6aD%2B1jNXE5F6pAs%2BxBkU1j4RNl6Ph98YJvCt%2Bks7AbBLDs3fOBTY8YcQ%3D%3D%7Ctkp%3ABk9SR57qjOfKYQ
Understanding the pulse rating of an SCR - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: June 01, 2016, 10:00:30 am
content: I am looking for an SCR for ignition coil discharge application.What I would be interested in is the Itrm which is defined asITRMRepetitive peak on-state currentThis is the maximum allowable repetitive peak current for a specified pulseduration at a specified case, ambient or lead temperature and frequency.however when I look in the SCR datasheet, for example thiswww.nxp.com/documents/data_sheet/BT151-800R.pdfone I find that the rating specified is ofITSMNon repetitive surge peak on-state currentThis is the maximum peak current allowed in the device under pulse coFor TRIACs, it is defined for a single full cycle sine wave of 20 ms correto the 50 Hz mains, and 16.6 ms for the 60 Hz mains.If the absolute rating is exceeded, the component may be damagedIs there a way to derive the Itrm from Itsm, I mean how would one determine the repetitive pulsed current rating of an SCR?Any help would be high appreciated.ZR

author: Marco
author_rank: Super Contributor
timestamp: June 01, 2016, 11:12:57 am
content: But that datasheet has them both ...

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: June 01, 2016, 05:04:44 pm
content: The graph at the bottom left of page 3/11 is that it? Its called Fig 1.I don't know how I missed it.

author: danadak
author_rank: Super Contributor
timestamp: June 01, 2016, 07:07:10 pm
content: If you can get your hands on GE SCR handbook that might be useful.https://www.amazon.com/Manual-Including-Triacs-Other-Thyristors/dp/0137967632?ie=UTF8&*Version*=1&*entries*=0Maybe there is a pdf scan of it online.Regards, Dana.
Understanding this metal detector design - Page 1
Forum section: electronics / beginners

author: AArdvark
author_rank: Newbie
timestamp: June 03, 2014, 10:14:22 pm
content: Hi,I found this Heathkit VLF metal detectorhttp://www.hobby-hour.com/electronics/s/groundtrack-gr1290.phpand became intrested in it. I think i have worked out how most of it works, there are a few bits i am not sure about and was hoping someone could explain them to me. This is for a VLF Metal detector which from what i have read looks for small phase changes to determine if metal is found.i may have this all wrong as i am new to electronics but i think thatQ8 L1 & L2 are acting as some type of oscillator transmitting a 7.3Khz signal.L3, Q1 & Q2 the signal is received by L3 and amplified by Q1 & Q2.Q9 & Q10 allow you to manually adjust the phase to correct for changes to the ground conditions etc. (this is because there may be a constant phase difference due to minerals in the ground, this can be effectively nulled out using Q9, Q10 does a similar task but to null out the types of metal you don't want ie ferrous)the output form Q9 and Q10 is fed into U4C which i think is working as a schmitt trigger to produce a square wave. this is then used to switch Q3.As Q3 switches some of the signal from Q1/Q2 will be allowed through, the amount of signal that come through will depend of if it is in phase or not.I think C8 is being used to smooth this signal so that the result is a varying voltage related to the phase. This is then fed into U2, I am not sure if U2 is an integrator or a single pole filter, i think its a filter as this would make more sense. The output of U2 controls the audio Q6 & Q7what i am really not sure about is U4A, Q5 and U1, to me it looks like U4A is a pulse generator which is switching Q5, U1 turns this into a triangle wave which is fed back into Q3 but i don't know why? the other odd thing is U4D which i think is being used to stop something only when the switch is used maybe stop the speaker from popping or something like that.After typing all it doesn't seem like a beginners question so sorry if this is in the wrong place. and thanks in advance to everyone that helps me with this. Please correct me if i am wrong about any of this.

author: jimmc
author_rank: Frequent Contributor
timestamp: June 04, 2014, 02:50:39 pm
content: It maybe easier to think of as Q3 / U2 forming a sample and hold phase detector, the DC output of U2 will depend on the amplitude and phase of the input signal.U4A generates an audio tone, Q11 chops the DC output (from U2 via R19 & 21) to give an AC signal whose amplitude is proportional to the DC.This is fed via Q6 & Q7 to the speaker / headphones. Thus the loudness of tone follows meter reading.As you say, U4D is part of a mute circuit which stops your ears getting blasted when switching between 'ground balance' and 'discriminate', it also appears to turn on 'auto tune' at the same time to quickly 'settle' U2.Jim
Understanding this voltage reference scaling circuit - Page 1
Forum section: electronics / beginners

author: new299
author_rank: Regular Contributor
timestamp: August 05, 2015, 09:07:44 pm
content: I've been looking at the attached circuit which is used with the AD5791 DAC to provide positive and negative voltage references from a 5v reference input.If I've understood correctly the circuit uses opamps to generate the + and - 10V references. One in inverting (for the negative) and non-inverting (for the positive). I had a few questions and was wondering if anyone could help?What is the purpose of R8? Why does the circuit use polarized (I think Tantalum?) and non-polarized capacitors for decoupling? C104 and C105 are not placed, but what is their proposed function?Thanks for any pointers!

author: Vgkid
author_rank: Super Contributor
timestamp: August 05, 2015, 09:21:15 pm
content: It looks to form a low pass filter with a cut off frequency of 10.61Hz

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 05, 2015, 09:51:59 pm
content: Hi,Quote from: new299 on August 05, 2015, 09:07:44 pmThe Tantalum capacitors are used for decoupling to provide damping. If the circuit was used on a bench and connected to a bench power supply with test leads, there is the possibility of high Q resonant circuit being formed between the ceramic decoupling capacitors and the inductance of the leads. If the circuit is hot-plugged there is the possibility of voltage transients. The ESR of the Tantalum capacitors provides damping.This is explained in this application note:http://cds.linear.com/docs/en/application-note/an88f.pdfC104 and C105 could be used to reduce the bandwidth of the amplifiers.Regards,Jay_Diddy_B

author: new299
author_rank: Regular Contributor
timestamp: August 06, 2015, 10:19:08 pm
content: Thank you, I'll check out the appnote linked!
Understanding three state logic - Page 1
Forum section: electronics / beginners

author: gkmaia
author_rank: Frequent Contributor
timestamp: September 04, 2020, 10:36:42 am
content: I need some help to understand a circuit.SRCLR and RCLR are always at 5V so always HIGH.If IC 2162 pin 6 is LOW then the voltage after R2168 is grounded as it flows through D2165 towards ground by three state pin 6 of IC 2162.This is what brings IC's 2165 pin 12 to LOW.Both D2165 and D2166 stop current from flowing from processor and IC2162 into RCK so they can IC2162 and PROCESSOR do not send each other current.Is the assessment correct?

author: ledtester
author_rank: Super Contributor
timestamp: September 04, 2020, 12:14:22 pm
content: The diodes and resistor form a simple AND gate:https://electronicsarea.com/or-and-and-logic-gates-with-diodes/If the cathode of either diode is LOW then current flows through the resistor bringing RCK LOW (or around 0.6V).If both cathodes are HI then RCK is pulled high by the resistor.
Understanding Vcm vs Vout graphs for Instrumentation Amplifiers - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: February 15, 2019, 03:39:09 pm
content: What is the significance of the Vcm vs Vout graph.I am planning to use the INA826, and I stumbled upon a posthttps://www.edaboard.com/showthread.php?361259-Problem-with-Instrumentation-amplifier-Gain-INA826regarding the same amp where the user was experiencing variation in gain when the output voltage crossed a particular threshold.I intend to use the same chip and would like to understand the Vcm vs Vout concept clearly before going ahead with the circuit.I am planning to power the chip @ 3.3V single supply and a gain of around 25, input would be in the range of 30 to 120mV so at that gain I would expect the output to vary between 0.75V to 3V.I am attaching the graphs below.

author: iMo
author_rank: Super Contributor
timestamp: February 15, 2019, 04:05:02 pm
content: http://www.ti.com/tool/ina-cmv-calc

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: February 15, 2019, 06:21:48 pm
content: Quote from: imo on February 15, 2019, 04:05:02 pmThat's an amazing link and amazing software. Although it is somewhat large for what its meant to do.The most important information in there is theHelpbutton imo!However it was worth the download from a conceptual understanding point of view!Many many many thanks!

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: February 15, 2019, 08:27:26 pm
content: Quote from: imo on February 15, 2019, 04:05:02 pmSomehow the software is showing a different graph from the one I posted above from the datasheet in my first post.
Understanding wiring method for 24 V DC output?  - Page 1
Forum section: electronics / beginners

author: PPryor
author_rank: Newbie
timestamp: June 17, 2024, 03:05:12 pm
content: Hi all, first time post.Within the following picture shows a 24v DC output to fire alarm door retainers keeping the doors open.Could somebody break down to me what method someone has used incorporating 2 diodes and 1 resistor.I’m assuming it’s in place to prevent EMC spikes to protect all components?Thank you in advance.Pete.

author: Xena E
author_rank: Frequent Contributor
timestamp: June 17, 2024, 03:25:36 pm
content: That's two diodes and one resistor.Not enough information to comment further sorry!Edit: probably an attempt at back emf protection.X

author: themadhippy
author_rank: Super Contributor
timestamp: June 17, 2024, 03:29:22 pm
content: wonder if its meant to be on the end of line to allow the panel to detect a fault?

author: SeanB
author_rank: Super Contributor
timestamp: June 17, 2024, 06:11:50 pm
content: There to provide both a sense resistor for the controller, as it will look for a small current flow to ensure the door circuit is always intact, but the one diode is superfluous, as what they are doing is driving a separate relay that operates a magnetic latch, likely because the original is no longer available, or draws more current than the existing driver can provide. Probably a separate module, that has a voltage level sensing, and the installer does not know that all they needed was a 12V relay board to boost the drive level, or the driver board came with the maglock assembly as the required controller.
Undervoltage recovery meaning - Page 1
Forum section: electronics / beginners

author: ctiger
author_rank: Newbie
timestamp: February 06, 2018, 05:25:38 pm
content: Hi all,I would like to know what does undervoltage recovery means. I have a compressor driver and under the specifications there are undervoltage protection @ 18V, undervoltage recovery @ 25V.I understand undervoltage protection is when <18V the driver shut off (correct me if I'm wrong), but I do not understand what does the recovery mean.Any opinions will be much appreciated.Thanks in advance.

author: ataradov
author_rank: Super Contributor
timestamp: February 06, 2018, 05:58:07 pm
content: Is it possible that 25 V is when it turns back on after turning off in undervoltage condition.This will make the gap between 18 V and 25 V to be a hysteresis, so there is no constant turning on and off at a crossing point.

author: ctiger
author_rank: Newbie
timestamp: February 06, 2018, 06:49:01 pm
content: The specifications stated that input voltage range of 18 V ~ 33 Vwithstand voltage range < 40 Vundervoltage protection @ 18Vundervoltage recovery @ 25Vovervoltage protection @ 33Vovervoltage recovery @ 30 Vso does that mean that within the range of 18 V to 25 V theres no switching on and off, I just got confuse about the recovery on the datasheet.Thanks again in advance.

author: ataradov
author_rank: Super Contributor
timestamp: February 06, 2018, 06:52:22 pm
content: Yes, it looks like it. So if voltage start raising from 0 V, output will first turn on at 25 V. Then it will be on until 33 V, and which point it will turn off. When voltage starts to drop and drops to 30 V, the output will go back on. And it will stay on until input voltage drops to 18 V.So whether there is voltage in 18-25 V and 30-33 V bands depends on what side you are approaching the band from.

author: ctiger
author_rank: Newbie
timestamp: February 06, 2018, 07:49:40 pm
content: Ok that make sense.Thank you Alex

author: Simon
author_rank: Unknown
timestamp: February 06, 2018, 08:26:01 pm
content: Take the case of an infinion smart switch, whose datasheet describes very well the reasoning. Say in the case of a smart switch (smart mosfet) you tell it to turn on and power a large load, if the voltage is dragged below the cutoff voltage it shuts down, having turned the output off the input voltage rises again, so it goes again and again trigger the low voltage cut off, the result is that the chip oscillates and overheats, because it keeps restarting the overheat protection can't function properly and it burns out. To prevent this they demand you put a decent amount of capacitance close by. You may have a similar problem but it sounds like they have tried to slow things down with a large hysteresis.
Unexpcted Behavoir of Small Capacitors - Page 1
Forum section: electronics / beginners

author: msuffidy
author_rank: Frequent Contributor
timestamp: March 24, 2022, 03:33:54 pm
content: In the attached diagram I would expect the capacitor pointed out is a noise reducing capacitor. I always expected capacitors would be connected sort of in parallel to a rail, and not in series with a rail. In this case, is this functioning sort of as a conductor? Does this differ from electrolytic caps? I don't think this is some sort of on low bias?

author: tooki
author_rank: Super Contributor
timestamp: March 24, 2022, 03:44:10 pm
content: A capacitor in series will block DC, but will permit AC to flow, so we call it a DC-blocking capacitor, or a coupling capacitor. (When you select “AC coupling” on an oscilloscope input, this is precisely what it’s doing: putting a capacitor in series.)A series capacitor and a resistor to ground, as shown here, is a CR high-pass filter. It blocks low frequencies and permits higher ones to pass.

author: tooki
author_rank: Super Contributor
timestamp: March 24, 2022, 03:47:10 pm
content: Take a look at this. I watched it the other day for fun, but it actually explains it REALLY well:

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 24, 2022, 03:48:58 pm
content: Coupling capacitor or differentiator.Likely the latter, which, amplified by a logic gate, will act as a one-shot timer. Likewise C2 acts as a (much larger, longer time constant) coupling cap, presumably to affect DC offset (sync?) of the output.Huh, and that's direct into the other gate's output? Will that do anything? ...Were 74LS outputs able to be dragged negative? They might be, I'm not sure offhand. Never tested it.So, it's a bit of a weird circuit, but I guess if it works, it works. It surely won't work with 74HC, or probably other 74xx families; definitely use the LS as shown.Note that, you still need a capacitor somewhere near the +5V/GND of this chip. It can be shared with others (in case this is a fragment of a larger schematic), or connected by a short length (say up to 10cm), but otherwise should be onboard, and maybe with an electrolytic (10uF say) too (say for connections over 50cm in length).Tim

author: SeanB
author_rank: Super Contributor
timestamp: March 24, 2022, 05:48:24 pm
content: LS still has input and output clamp diodes, simply because input side is a transistor base emitter junction, and then there is a parasitic substrate diode for negative transients. Put too much current into them and you latch up the parasitic SCR structure intrinsic to the chip, making it go somewhat non functional, and if the power supply can provide enough current it will let out smoke.