Power supply, build or buy? - Page 1
Forum section: electronics / general

author: Mint.
author_rank: Frequent Contributor
timestamp: December 26, 2011, 03:04:03 am
content: I am really in need of a power supply now. I was thinking, should I maybe buy one or build one myself. I am not really sure about the specs that I may need. This would be my first power supply and at the moment the most that I needed so far was 12v and 1A.

author: Psi
author_rank: Super Contributor
timestamp: December 26, 2011, 03:51:56 am
content: If you're interested in building a power supply then you should do it.Dave is working on a simple yet complete power supply design in the current blogs.You can skip the digital control parts if you would rather keep it simple and have a potentiometer for voltage/current control.That way you won't need a micro controller. The whole thing would be discrete components and IC's.I'd recommend powering it from something like a 15V DC power pack. They're easy to get and safe.On the other hand, if power supplies don't really interest you and you have other projects you want to do that require a powersupply then i recommend buying one.

author: Lightages
author_rank: Unknown
timestamp: December 26, 2011, 04:03:04 am
content: Building is a learning experience and has the benefit that if something breaks you know exactly how it was built and how to fix it.Buying is cheaper and you usually end up with a more professional looking piece of equipment but you don't necessarily know how to fix it should something go wrong.If this is your first build, you have a better chance getting something reliable by buying.

author: Mint.
author_rank: Frequent Contributor
timestamp: December 26, 2011, 04:07:11 am
content: I do have a bit of experience building things myself. So I will attempt to build the supply myself. But honestly I found Daves power supply videos hard to follow because I do not understand many aspects of what he's talking about.

author: vtl
author_rank: Regular Contributor
timestamp: December 26, 2011, 08:04:31 am
content: I recommend buying one.http://www.ebay.com.au/itm/ATTEN-Adjustable-Variable-DC-Power-Supply-30V-3A-240V-/130526601207?pt=AU_B_I_Electrical_Test_Equipment&hash=item1e63fddff7This is a great power supply for the money.I considered building one but to actually build something equivalent to the above product is quite difficult for the same amount of money. You'd need to source a transformer, nice box and display and heatsink and all the analog circuitry. Its possible to get it done cheaper than buying one only if you salvage all your parts. But its unlikely you'll end up with something as nice as a proper product as well. For example, any decent linear power supply will have a multitap transformer with relays that switch the voltage so you waste less power in the pass transistor.Going DIY and powering it from a simple transformer plugpack is an option but its unlikely you'll have one that will do a couple amps without melting. A laptop charger is switch-mode and would work but then you gotta worry about switching noise. Can be quite diffcult to get rid of even after putting LC filters on the output.My suggestion is to buy your first power supply then go build your own as a second PSU. You'll likely realize that 1 bench power supply isn't enough and in a lot of cases you'll need a few to provide multiple rails for your projects.

author: Hypernova
author_rank: Unknown
timestamp: December 26, 2011, 11:42:32 am
content: Buy one and then use that to build another! During the building process there will be times when you need to test individual functions and that's where another PSU come in. Basically bootstrapping in hardware.

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 26, 2011, 03:06:05 pm
content: Quote from: MintyCondition on December 26, 2011, 03:04:03 ama cheapo china PC/atx psu is good (more than your spec) enough to get me starting. once i bought 5 unit in one receipt because it was so damned cheap. the bad thing is it can be dead easily if you dont be careful with overcurrent. i think i have the last one working now, the other are left for parts recycling project.

author: ipman
author_rank: Regular Contributor
timestamp: December 26, 2011, 07:27:10 pm
content: A good trade will be building a power supply from a kit. There are quite few of them based on 7812, even rated for 1.5A.

author: robrenz
author_rank: Super Contributor
timestamp: December 26, 2011, 07:53:52 pm
content: If I heard correctly on the AmpHour, Dave's power supply is going to be a kit. I would certainly wait until you see that before you take any action. It will certainly be a top notch design and and be cheaper in the long run (unless you happened to already have all the parts in your personal stock).

author: Bored@Work
author_rank: Super Contributor
timestamp: December 26, 2011, 09:21:05 pm
content: Quote from: Lightages on December 26, 2011, 04:03:04 amBuilding one doesn't guarantee this. A lot of people just build some existing design without understanding it.Quote from: robrenz on December 26, 2011, 07:53:52 pmWell, from the specs it might be a nice additional supply. But for a start I would recommend a general purpose supply with more than 5 to 6V max. output voltage. 5V to 6V is good for a lot of things, but not for all.Also, DIY power supplies are hardly to be done cheaper than some garden-variety Made in China bench power supply. E.g. beating $90 for something like thishttp://www.mastechpowersupply.com/dc-power-supply/linear-power-supply/mastech-regulated-variable-dc-power-supply-hy3003d-30v-3a/prod_2.htmlis difficult.

author: robrenz
author_rank: Super Contributor
timestamp: December 26, 2011, 10:00:00 pm
content: Quote from: BoredAtWork on December 26, 2011, 09:21:05 pmI don't think the 5-6 volts is the final spec.Quote from: BoredAtWork on December 26, 2011, 09:21:05 pmAgreed, I have a mastech I am very happy with but I meantIfyou are building one.

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 26, 2011, 10:37:28 pm
content: Quote from: robrenz on December 26, 2011, 10:00:00 pm12V with more than 1A my minimum, maybe around 5A min. for op amp design, -ve rail!

author: Psi
author_rank: Super Contributor
timestamp: December 27, 2011, 12:07:52 am
content: Quote from: MintyCondition on December 26, 2011, 04:07:11 amBest way to fix that is to post about the bits you don't understand.

author: rickselectricalprojects
author_rank: Regular Contributor
timestamp: May 03, 2015, 11:32:02 am
content: It all depends on what you want to use your power supply for. If you need a wide variety of different voltages than get a cheap variable one of ebay for $70. But if you only need 3.3v,5v and 12v than you can easily convert a computer power supply to bench useI know this post if very old but i hope this helps

author: lapm
author_rank: Frequent Contributor
timestamp: May 03, 2015, 11:36:31 am
content: Quote from: Hypernova on December 26, 2011, 11:42:32 amI was about to say this...Get one first so you can get started with electronics. You can later build one yourself if you feel like its something you'd like to learn..

author: Mechanical Menace
author_rank: Super Contributor
timestamp: May 03, 2015, 12:23:58 pm
content: Quote from: rickselectricalprojects on May 03, 2015, 11:32:02 amPC PSUs tend to be very noisy though so while that's a great option if your primary interest is digital stuff as soon as you get to interfacing with anything analogue it can cause problems if you're not expecting the issue.

author: ez24
author_rank: Super Contributor
timestamp: May 05, 2015, 03:53:31 am
content: my first question is the OP still alive ?this topic started over 3 1/2 years ago, over 1 year since he has shown up

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 05, 2015, 04:00:35 am
content: Quote from: Mechanical Menace on May 03, 2015, 12:23:58 pmNot if you use a good quality one. Of course, then it won't be that cheap...