Timeline for Buck converter based switching power supply?
Current License: CC BY-SA 3.0
31 events
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| May 18, 2015 at 2:20 | comment | added | Russell McMahon♦ | ... requirement. It should not be a wide conversion voltage range buck converter* as there are too many problems and other ways are easier and better. It needs you to know quite a alot more than you do - needing to learn is fine - but this design is not the one you want to learn about or learn on. || *-Wide conversion ratio buck converters can be implemented but the need has to justify the complexities faced. In this case it doesn't. I had an application where Vout:Vin varied from 1:1 to over 17:1 and I needed ultra low cost. A buck converter made sense in that case - but its very unusual. | |
| May 18, 2015 at 2:14 | comment | added | Russell McMahon♦ | OK. Listen .... STOP. If the application of this power supply is as you say and if you want the project to work, this is not the way to do it. Even if this worked perfectly it would not be what you want or need for your project. Yhe reasons are already covered in comments and my answer. The most logical (and cheapest) path is to find an existing power supply that meets your need. Then once your main project works properly come back to making your own power supply if you still want to. It needs to be isolated with a properly related transformer - this is a sensible, ethical and regulatory ... | |
| May 17, 2015 at 23:48 | comment | added | Russell McMahon♦ | @Andyaka You need to get out of bed on the OTHER side (again) :-) ) | Damned if he does. Damned if he doesn't. No? The idea is that bad questions should be improved. This has improved immensely | This started off as a vey closable questsion BUT has evolved reasonably well into something that can serve as an education for others as well as the OP. If your comment had been made early on then maybe OK. But if you think questions like this should be closed there is an awfully large amount of other housekeeping needed here. | |
| May 17, 2015 at 22:19 | history | edited | Allenph | CC BY-SA 3.0 |
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| May 17, 2015 at 21:53 | answer | added | Adam Haun | timeline score: 3 | |
| May 17, 2015 at 19:47 | review | Close votes | |||
| May 19, 2015 at 15:33 | |||||
| May 17, 2015 at 19:29 | comment | added | Andy aka | I'm voting to close this question as off-topic because it requires too much correcting and learning by the op to get the question to a minimal decent standard. | |
| May 17, 2015 at 19:18 | answer | added | tcrosley | timeline score: 1 | |
| May 17, 2015 at 18:42 | comment | added | Russell McMahon♦ | re " ... Well, the whole reason I got into electrical engineering is to build a very specific project. It hinges on the power supply. ..." -> THEN you need to very specifically tell us about your requirement. It is extremely hard to imagine that a very specific project that is important to you hinges on you taking the approach that you are. If you need to power a low voltage circuit from main AC then there are a very large number of circuits or approaches that you could use that are superior to what you are trying. If you have a need that justifies this approach then we need to know it. | |
| May 17, 2015 at 18:01 | answer | added | Russell McMahon♦ | timeline score: 2 | |
| May 17, 2015 at 17:26 | comment | added | Russell McMahon♦ | an Indy 500 race car in mid level competition. Not only much harder than necessary but makes minimal sense and endangers yourself and others. Pleasing "just theoretical" is not good enough. It's not what your question actually says and doing it offline adds issues which are not needed when learning. Doing it discretely also adds issues of hardness and ADDS complexity you do not need and will not benefit from. FWIW - I have implemented fully discrete buck regulators with 200V+ input and 12V output in a production situation - I assure you that that is not where you want to start :-). So ... | |
| May 17, 2015 at 17:21 | comment | added | Russell McMahon♦ | Your diagram is MUCH better (but still conceptually wrong - see below). BUT my original point (1) is stll crucially applicable - ie "(1) What you re trying can be lethally dangerous and it is not the right starting point" - You are unab;e to change this - what you are doing is potentially fatal to you or the circuit or both. It will be vastly more valuable to yourself (and safer) to start off with a probably cheap effective known design that teaches you the basic principles. Trying to design and build a discrete component off line switcher is somewhat akin to learn to drive in ... | |
| May 17, 2015 at 11:43 | history | edited | Allenph | CC BY-SA 3.0 |
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| May 17, 2015 at 11:23 | history | edited | Allenph | CC BY-SA 3.0 |
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| May 17, 2015 at 10:46 | history | edited | Allenph | CC BY-SA 3.0 |
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| May 17, 2015 at 10:37 | comment | added | Allenph | @Andy aka, I have added the base resistors. However, their values are undefined for similar reasons to those detailed in my question. | |
| May 17, 2015 at 10:36 | history | edited | Allenph | CC BY-SA 3.0 |
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| May 17, 2015 at 10:29 | comment | added | Allenph | I have completely redrawn the circuit. It's a lot easier to read now. Please keep in mind that this is a fundamental drawing, and the question insinuates that this probably will not work the question is asking why that would be the case, if it is. Please try and take it easy. | |
| May 17, 2015 at 10:28 | history | edited | Allenph | CC BY-SA 3.0 |
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| May 17, 2015 at 10:24 | history | undeleted | Allenph | ||
| May 17, 2015 at 9:32 | history | deleted | Allenph | via Vote | |
| May 17, 2015 at 9:31 | comment | added | Allenph | I have made edits to accommodate your critique. I apologize for the errors in the circuit drawing. Circuit explanation has been added. @Andy aka, I'm afraid I don't know what you mean by "base resistors." | |
| May 17, 2015 at 9:30 | comment | added | user16324 | Stop. Just stop. Learn how to connect and operate a single transistor. Then come back to this circuit and you'll see it's completely wrong - even after connecting NPN2 the right way round, it's now an emitter follower which really won't do what you want. | |
| May 17, 2015 at 9:30 | comment | added | jippie | Maybe this can be of some help: electronics.stackexchange.com/questions/28251/… Your circuit layout can use some ironing. | |
| May 17, 2015 at 9:24 | history | edited | Allenph | CC BY-SA 3.0 |
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| May 17, 2015 at 9:22 | comment | added | Andy aka | Base resistors are not optional - please put them in. Q1 is backwards. This is a total mess. | |
| May 17, 2015 at 9:11 | comment | added | jippie | Agreed with @RussellMcMahon. For others to understand a circuit diagram it helps if you discuss its intended operation. Also, the load is missing. Draw it as a resistor. | |
| May 17, 2015 at 9:11 | comment | added | Allenph | Well, the whole reason I got into electrical engineering is to build a very specific project. It hinges on the power supply. I should have detailed the function of U1. I will add that momentarily. I will also add a circuit explanation. My apologies for the sub-par circuit drawing. | |
| May 17, 2015 at 9:11 | comment | added | Russell McMahon♦ | ... |If you are serious about learning start with a low voltage AC powered circuit (say 12 VAC in). Look up all the application notes and data sheets for a MC34063 and start with that. Flexible and cheap. | If you do not improve the digram and question asap the people who do such things WILL put it on holdor close it. | |
| May 17, 2015 at 9:08 | comment | added | Russell McMahon♦ | It's commendable that you are attempting this but (1) What you re trying can be lethally dangerous and it is not the right starting point. (2) Your circuit has inadequate information to get a useful answers and it is drawn so badly that even very experienced pople will have troub;e working out what you are trying to do amnd what mitakes have been made. | You cannot just say "U1", provide no details and not all connections. Your transistors are not driven realistically. None of your transistors are connected in a way that suggests they will do anything useful.... | |
| May 17, 2015 at 6:52 | history | asked | Allenph | CC BY-SA 3.0 |