Andy aka

general recent conversations

Discussion on question by LvW: Is a s…

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Andy aka

Jun 15 14:16

Answer to question in title: no, unless you are ruling out simulation.

Discussion on question by Rajesh R: W…

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Andy aka

Apr 5 18:10

Not enough. Your new words contradict your original table of numbers. Look this should be easy but, you are making it hard on yourself.

Andy aka

Apr 5 18:10

The writing is on the wall @RajeshR <-- this question will be closed sooner or later unless you make an attempt to improve it and show your attempt at working this out.

Andy aka

Apr 5 18:10

You know you could help yourself a lot by revealing the full circuit and doing a plot of angle vs voltage in something like excel. You shouldn't rely on folk doing this for you unless you are lucky to find someone who is compelled to do so.

Discussion on question by user539411:…

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Andy aka

Mar 27 13:47

@RussellMcMahon I said the solution is to connect it between drain and gnd; you think for some reason (that I can't follow) that I mean to reverse the TVS/diode. That is NOT what I am saying in my answer. Quote: If you want to prevent the MOSFET drain rising above a certain voltage use a very tough TVS or Zener connector from drain to GND

Andy aka

Mar 27 13:47

You clearly haven't comprehended my answer. Read it again.

Andy aka

Mar 27 13:47

He didn't make it clear at all that a bidirectional TVS diode was being considered. Your amendments went down a line of presuming that it was bidirectional and that was a step too far in my book @RussellMcMahon ||| The op should consider carefully amending the question so that it pays credence to all current answers.

Andy aka

Mar 27 13:47

@RussellMcMahon schematic is still king but, hopefully, the OP has learned a valuable lesson about submitting information that is accurate at the time of first posting.

Andy aka

Mar 27 13:47

@RussellMcMahon the way around this is for the OP to carefully and clearly acknowledge the answers given prior to changes then, introduce the changes in such a way so as to give further life to the question. The wrong way is to simply obliterate what was their previously and make my answer look stupid.

Andy aka

Mar 27 13:47

I've rolled back your question to a state that does not contradict information provided when you published the first schematic diagram upon which I made my answer. Golden rule: measure twice and cut once.

Andy aka

Mar 27 13:47

@RussellMcMahon you have edited the question to provide a link to an unsubstantiated TVS diode. What on earth prompted you to do this i.e. the 5kp65ca does not exist in the data sheet linked. Why not leave it to the OP to make things clearer. I think you are on shaky ground.

Electrical Engineering

A place to talk with friends from the EE community about vacuu...

Andy aka

Mar 24 18:37

@NickAlexeev I've only ever used el cheapo 433 MHz modules (back in they day when they appeared) so can't really advise.

Room for p_karis and Andy aka

Andy aka

Mar 21 16:41

@p_karis I strongly advise you to find out what is on the market and make that your starting point (if close enough)

Andy aka

Mar 21 16:04

@p_karis You need to delve into what is available on the market regarding voltages and currents and methods of fencing. I never use LTspice so that's a no. I think 200 Hz is too fast (look into regular electric fences is my advice). For voltage doublers you need to find diodes that are rated at circa 20 kV and these will be hard to get.

Andy aka

Mar 21 14:15

@p_karis 400 kV is far higher than I would feel comfortable with. I know it's for elephants but in all seriousness, the highest kV I've ever done on one design is 50 kV at 2 mA for an x-ray power supply. Have you delved into electric fence designs to see what comes closest to your requirement. When you reply click in left area next to the start of this message then, it appends my ID so I know you are contacting me.

Andy aka

Mar 21 13:33

@p_karis Are you not able to solve the problems by asking questions on the main site?

Discussion on question by ShikShoxF1:…

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Andy aka

Mar 2 15:36

That schematic is chaotic, unrefined, obfuscated and hurts my eyes. I'm normally pretty good at figuring out badly drawn schematics but yours is beyond what I would ever attempt. A schematic is not just a means to an end but a statement of the design. It needs a complete logical redraw. that's an invitation btw.

Discussion on answer by Andy aka: Vol…

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Andy aka

Feb 27 17:06

@Kokachi if it's a constant current source then it doesn't matter where you place it but, I'd favour nearer the 12 volt supply.

Andy aka

Feb 27 17:06

Try it at 12 volts first @Kokachi

Andy aka

Feb 27 17:06

It looks modifiable although the schematic is a little blurred @Kokachi

Andy aka

Feb 27 17:06

The image in my question is just one suggestion. Have you looked into the module you want to buy to see if it can be easily modified @Kokachi ||| I mean, all you say in your question is "boost converter" and not a "boost converter module".

Andy aka

Feb 27 17:06

Please read my added words beginning with where I quote your words: I was hoping to connect a boost converter to boost up to 15 volts

Andy aka

Feb 27 17:06

Solution A and B will cause problems so, can you afford problems? If not then choose solution C.

Andy aka

Feb 27 17:06

Price has got nothing to do with my answer. My answer is all about the most reliable and trouble free solution.

Discussion on question by Timo: PWM c…

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Andy aka

Feb 13 18:01

@Timo where is that 10 ohm resistor connected to? If it's connected to the 12 volt node on the previous diagram then it is not PWM. It's all getting confused and messy now.

Andy aka

Feb 13 18:01

""MOSFET stays open" <-- that's a hydraulic term; we use open to mean open-circuit in electronics. Additionally the 12 volt output is from a buck regulator so you can't realistically derive PWM from it unless you really do know what you are doing.

Power supply design

discussion about power supply design

Andy aka

Feb 11 23:24

@RyanGriggs Good luck Ryan

Andy aka

Feb 11 18:56

@RyanGriggs The capacitance loss of some ceramics is really problematic if you are relying on them for ripple reduction. The only countermeasure is more capacitance. If the resonance is 13 kHz (correct) then you want the RC phase shift to be significant at this frequency. If you don't use the little pull-down menu on the left side of a new comment you can't directly reply to it and I don't get a notification hence, the lateness.

Andy aka

Feb 10 09:48

5. No don't assume a mistake. If you want a power good LED then use an extra transistor to invert the logic.

Andy aka

Feb 10 09:47

4. Read the absolute maximum ratings. The EN pin can withstand more voltage that the maximum supply voltage from memory

Andy aka

Feb 10 09:46

3. you have a closed-loop system with potentially a phase shifting network of 180 degrees inside the loop. That's the inductor and output capacitor so, to avoid your circuit turning into an oscillator you need to reduce the phase shift at higher frequencies.

Andy aka

Feb 10 09:44

@RyanGriggs 2) You can pick bigger than what is required but generally the bigger the inductor the lower the self resonant frequency (SRF) is and, if you are running at 100 kHz you want the SRF to be at least 2 MHz in my book.

Andy aka

Feb 10 09:41

I always use Kemet for capacitors and they have tools on their product pages that give you exactly what I need to know. Buy cheap and you don't always get what you expect I'm sorry to say. My philosophy for decades has been buy the best materials and the time it'll save down the line in figuring out problems and product recall more than pays for itself.

Andy aka

Feb 10 09:38

Page 15 of the data sheet linked on the CL31B106KLHNNNE page shows a graph of temperature rise vs ripple current vs frequency. It's a for an X5R but X7R will be no worse.

Discussion on question by Alfie Wren-…

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Andy aka

Feb 6 14:28

What current are you referring to? Why haven't you shown simulation waveforms?

Discussion on answer by Andy aka: Can…

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Andy aka

Jan 20 14:23

@misk94555 why don't you just post a proper question instead of all this cloak and dagger stuff

Andy aka

Jan 14 15:06

@TQQQ your question was clear (Am i right or am i missing something) and I'm saying you are not right. Additionally you said you were going to simulate yet, we are instead going round in circles.

Andy aka

Jan 14 15:06

I'm sure I'm not wrong but, if you want to do a simulation and post the images then that's up to you @TQQQ

Andy aka

Jan 14 15:06

I'm sorry you don't understand inductors fully. It's true that the current can't change instantaneously but, when the lower FET deactivates, for the inductor current to keep flowing in the same direction, the load side of the inductor has to be more positive than the input side and, the inductor back emf ensures this. Hence, for this arrangement to work, the output voltage can only be controlled when it is bigger than the input voltage.

Andy aka

Jan 14 15:06

@TQQQ when the inductor delivers energy to the load and output capacitor it can only do so when the output side of the inductor is at a voltage greater than Vin so, what you are describing is an invalid condition.

Andy aka

Jan 14 15:06

@TQQQ if the load were drawing 10 amps then what is the volt drop across the inductor (bearing in mind that the lower GaN FET has to be turned off (deactivated) and the upper one turned on (activated) for this to happen.

Andy aka

Jan 14 15:06

With the MOSFET switches inactive, Vout acquires virtually the same value as Vin through channel leakage. This means no-matter what you do with the activation of the switches, you cannot regulate below Vin. Not activated means not activated i.e. gate and source voltage the same @TQQQ

Discussion on question by Allfadern: …

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Andy aka

Nov 20, 2024 17:14

Have you simulated your circuit? If not why not?

Discussion on question by neural: Wil…

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Andy aka

May 21, 2024 19:53

Totally, totally and totally.

Andy aka

May 21, 2024 19:53

Sorry I wasn't really clear about this; it isn't a prediction it's a rock-solid, gold-plated certain guarantee. I don't rip stuff apart when I design transformers so no, I can't help. You will find my methods alien.

Andy aka

May 21, 2024 19:53

This is very much a bushcraft kind of design and I understand that, and if you tell me this is a really bad idea I won't do it <-- don't do it because your idea at making the transformer stinks. Electronics isn't akin to bushcraft at all. Don't convince yourself that there is any similarity. transformers are not rocket science, give me a little credit please. <-- sorry but if you didn't realize that a fully conductive core will blow the fuses then maybe you need to re-assess your knowledge levels.

Discussion on question by Dragonfly3r…

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Andy aka

May 3, 2024 19:15

It looks like the supposed CM choke is being used differentially (DM) and, this could be either an error on the original Chinese board or, an error in your reversing or, unusually, it may be correct. Either way, it looks wrong. Reverse engineering a power supply from China is usually a bad thing to do. There are plenty of bona fide examples out there and, like winny says you MUST simulate the circuit to make sure it works.

Discussion on question by dhuwarkesh:…

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Andy aka

Apr 18, 2024 18:00

Please use a simulator. There is no excuse these days not to.

Discussion on question by Circuit fan…

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Andy aka

Apr 8, 2024 18:13

Your simple analysis has an error. Please don't thank me for pointing this out because I also agree with @pipe.

Discussion on question by JoeyB: Why …

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Andy aka

Apr 5, 2024 20:07

@JoeyB it's shielded so, unless there's a data sheet for an unshielded one that fits the same footprint that's as far as I would like to go.