Decent Modern Power Supply Kit for 120VAC input? - Page 1
Forum section: electronics / testgear

author: R2D2
author_rank: Newbie
timestamp: February 23, 2014, 04:47:39 pm
content: Hi Everybody,I'm in the market for a decent power supply kit that will work in the USA (120VAC input). I'll need at least 24VDC and 5A, but I wouldn't mind having 30V available. Perhaps someone here can point me in the direction of something worth building and using? If the current kits are all rubbish, what currently available modern power supply is the way to go? I'm having a go at putting together an electronics lab in my garage for my retirement years.Thank you!

author: liquibyte
author_rank: Frequent Contributor
timestamp: February 23, 2014, 05:50:01 pm
content: http://www.electronics-lab.com/forum/index.php?topic=19066.0maybe? I'm building the 3A version now.

author: R2D2
author_rank: Newbie
timestamp: February 23, 2014, 06:00:36 pm
content: Quote from: liquibyte on February 23, 2014, 05:50:01 pmTHANK YOU for that link liquibyte! I'll get another cup of coffee and start chewing on that thread.

author: liquibyte
author_rank: Frequent Contributor
timestamp: February 23, 2014, 06:54:15 pm
content: I can give you my parts list if you like but I'm building the 3A version twice as a dual supply so R7 and the transformer will be different at the least. I'm not sure if much else changed between the designs but there are two seperate threads on that board discussing the same supply and in one of them another guy made a picture showing the parts differences. You'll also need an extra 2N3055 to handle the extra current. The guy that came up with the 5A version also used a microwave transformer that he wound the secondary on himself using copper tape I believe. I got most of the parts, including the transformers, off of Digikey.

author: R2D2
author_rank: Newbie
timestamp: February 23, 2014, 08:50:40 pm
content: Quote from: liquibyte on February 23, 2014, 06:54:15 pmYour parts list would be greatly appreciated. I'm actually planning on building a couple/few power supplies. They look to be quite interesting as a beginner type project. I'll probably buy an old Agilent/HP and grab a Korad at some point too... something that doesn't have my fingerprints all over the place inside, and thus may be accurate & reliable.I've been using this place for a couple of months to start a collection of components and they have the 2N3055 in stock:http://www.taydaelectronics.com/2n3055-npn-af-amp-audio-power-transistor-15a-60v.htmlThanks again!

author: liquibyte
author_rank: Frequent Contributor
timestamp: February 23, 2014, 09:20:04 pm
content: I'm attaching this as a pdf so you can save it to your computer without much trouble. Also, this isn't a complete list of everything that I've gotten to build these, just the electronics bits. I also purchased knobs, quick connects, fuse holders, etc... I also haven't gotten everything I need for the displays I'm designing but have most of it already.I forgot to mention that I got this heatsink for the TO-3's from thisguyon ebay. I'm actively cooling these with two 80mm fans I had on hand. Can't beat $16 and change for a heatsink of this size.

author: R2D2
author_rank: Newbie
timestamp: February 23, 2014, 11:27:15 pm
content: Quote from: liquibyte on February 23, 2014, 09:20:04 pmThank you for the parts list. I'm finding this to all be quite interesting. I do not yet have an oscilloscope but I've been reading up a bit. This looks like a project that could perhaps use one.

author: liquibyte
author_rank: Frequent Contributor
timestamp: February 23, 2014, 11:47:43 pm
content: I'm doing this without one and I imagine that it's not totally necessary. I have one but it's an old Conar 255 that I traded a member here for and I don't yet have probes for it. I think it's just a 10MHz scope too so I'm not sure how useful it's going to be but at least I have something to play and learn with. The manual has schematics for building probes for it so I think that's what I'm going to do but I haven't gotten that far with it yet because I've been busy designing this project into a case I have and it's taken quite a bit of time so far but I am enjoying the process. Basically I'm going to have two of these linked at the output with a lighted toggle to combine them into a basic positive and negative output configuration. I think I may be able to get 60V @ 6A out of this as well but I don't think I'd ever have a need for such a beast and probably will never use it like that. I'm taking my time with this so as to get things done the right way the first time.

author: R2D2
author_rank: Newbie
timestamp: February 24, 2014, 12:50:47 am
content: I'll have to go over that thread again to find the latest 3A version schematic to see what you're building. 3A is probably fine for most of my needs. I'm just used to the 40A 24VDC supplies all over the place where I work at powered by 480VAC 3 phase and figured 2A extra might be a nice target range.

author: liquibyte
author_rank: Frequent Contributor
timestamp: February 24, 2014, 01:22:04 am
content: Here is the schematic from the thread along with the parts list.

author: R2D2
author_rank: Newbie
timestamp: February 24, 2014, 04:16:04 am
content: Quote from: liquibyte on February 24, 2014, 01:22:04 amAwesome! I ordered most of the components tonight from Digi-Key and Tayda. I'm going to just build the standard model to start and then use it as a base to learn more by adding a micro controller and displays and whatnot.This is going to be fun! Thanks again for your help.

author: liquibyte
author_rank: Frequent Contributor
timestamp: February 24, 2014, 04:36:57 am
content: Glad I could help. I was going to add displays using a 328p and AS1100PL's but I haven't worked out the circuit yet. I know it's not going to be terribly accurate but I wanted to roll my own as a learning experience. There's a thread on here about using arduino as an accurate voltmeter but it kind of decended into a metrology discussion. I was thinking 3 1/2 digits voltage should be enough with 2 1/2 for the current side of things.