power supplies - Page 1
Forum section: electronics / beginners

author: orbiter
author_rank: Frequent Contributor
timestamp: May 08, 2010, 02:10:03 pm
content: Hi all,What would you guys recommend as a good starter PSU replacement instead of using up batteries all the time. The unit would be for small circuit builds and testing computer components etc.I was looking at something like this..http://www.cybermarket.co.uk/ishop/923/shopscr1562.htmlOr would I be better off with something with a little more headroom like the 10A one at the botom left of this page..http://www.cybermarket.co.uk/ishop/923/shopscr96.html?gclid=CKXEztDawqECFUiX2AodXEB6_gOr even one of these..http://www.circuitspecialists.eu/triple-output-dc-bench-power-supply-lcd-display-csi-3003xiii-p-167.htmlWhat are your thoughts please?Thanksorb

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 08, 2010, 02:26:38 pm
content: computer components needs multiple and stable voltages .For such a task it best to get one normal PSU made for computers , and to activate it by bridging the Green wire .You can even make or buy a metal box , and add to it Ampere meters and volt meters at every output.And you will have you own home made PSU+Tester , even with built in protections ..Simple as that ..

author: armandas
author_rank: Frequent Contributor
timestamp: May 08, 2010, 02:28:11 pm
content: You can get a good used power supply for the the same price! Here is one for example:http://cgi.ebay.co.uk/Thandar-TS1542S-Dual-Power-Supply-/180496733533?cmd=ViewItem&pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item2a0671955dSmaller ones can be had for even less. Just keep an eye on ebay until you find what you need.

author: orbiter
author_rank: Frequent Contributor
timestamp: May 08, 2010, 02:53:20 pm
content: Thanks for the responses fellas. I was actually thinking more along the lines of a bench PSU for quickly testing the likes of hard drive motors and peripheral components were dragging an actual computer PSU with all it's wires trailing around would be a pain in the butt. So something like the bench PSU here would be greathttp://www.circuitspecialists.eu/triple-output-dc-bench-power-supply-lcd-display-csi-3003xiii-p-167.htmlplus it would have plenty of headroom for further experiments which would be greatregardsorb

author: armandas
author_rank: Frequent Contributor
timestamp: May 08, 2010, 03:15:04 pm
content: The one I linked to is a bench PSU. Here is the manufacturers website for more info:http://www.tti-test.com/products-tti/psu/ts-series.htm

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 08, 2010, 03:48:13 pm
content: Well the only that I can think of , are that any bench PSU capable to stand next to an 200$ well made computers PSU , it will cost at list double or triple .Its best to say the max price, that you are willing to pay, so to get useful feedback about your question.

author: orbiter
author_rank: Frequent Contributor
timestamp: May 08, 2010, 04:02:10 pm
content: Quote from: armandas on May 08, 2010, 03:15:04 pmThanks mate, I'll bear that one in mind whilst I'm looking around.

author: orbiter
author_rank: Frequent Contributor
timestamp: May 08, 2010, 04:09:46 pm
content: Quote from: Kiriakos-GR on May 08, 2010, 03:48:13 pmYes, I understand. For most of my computer builds I actually only use top end Enermax Revolution 1250W PSU's, they cost around £230 each but for the systems I build it's worth it. I think for a bench PSU I would be willing to spend around £150 as I don't really want to start converting an Enermax PSU's into a bench PSU when I can buy a bench supply cheaper.Orb

author: Unknown
author_rank: Unknown
timestamp: May 08, 2010, 05:59:29 pm
content: For bench work, a $200 bench PSU is much better than a $200 computer PSU. A computer PSU is mainly useful for... computers! Or something else which needs lots of current at 12V and some current at 5V, and doesn't require low noise.Advantages of bench supplies:Adjustable current limit, instead of being able to deliver at least 20A (plenty to blow up internal protection diodes and vaporize bond wires), and having a polyfuse (slow, finite life time) as short-circuit protection (if that).Adjustable voltage up to at least 20V, instead of a fixed 12V and 5V. You can get creative with -12V, but they can deliver very little current, and the supply might get unstable.Floating operation. A computer PSU is almost always grounded.Usually linear, which means less noise on the output signal.The only positive for a computer PSU is that it can deliver lots of current, which isn't a requirement for most projects.You can also get cheap bench supplies which are probably decent if you don't expect them to actually deliver the max. power. It's also not that hard to make them if you already have a suitable transformer and heat sink.

author: orbiter
author_rank: Frequent Contributor
timestamp: May 08, 2010, 06:18:09 pm
content: Quote from: alm on May 08, 2010, 05:59:29 pmYea that was basically my way of looking at it too Alm. Especially the variable voltage and current options, as some of the PSU I use have 70A rails which is no good really for hobby use. Anyway it's sort of a toss up now between the Bench model above that armandas directed to or this, which I actually prefer as it's brand new and will have a warrantyhttp://www.circuitspecialists.eu/triple-output-dc-bench-power-supply-lcd-display-csi-3003xiii-p-167.html

author: Unknown
author_rank: Unknown
timestamp: May 08, 2010, 06:31:30 pm
content: Disclaimer: I don't have experience with either. The TTI one is probably better made (although the 2x15V is a bit low), the resolution of the meters is higher (I do often put a DMM in series to get better than 10mA resolution on mine, so I would value the extra digit), and it's probably more precise (eg. able to use external sense connections). The CircuitSpecialists one looks more like a typical Chinese product: lots of features, but the quality is less clear. The features do look pretty good, although the fan might be annoying (not sure if the TTI one has a fan?). I wouldn't worry as much about warranty as long as it's well-made, they don't break that often, and are often easy to repair (just a power transistor or electrolytic caps).

author: orbiter
author_rank: Frequent Contributor
timestamp: May 09, 2010, 10:40:41 pm
content: Quote from: alm on May 08, 2010, 06:31:30 pmThanks for the info almOne thing I was wondering please regarding the following paragraph for the PSU I was looking at is.... Do all PSU's use the method described below to set their Current limit?Also.. Given the option for a first time bench PSU user, would you go with the 3A or 5A PSU model. Price difference is negligable.Quote

author: armandas
author_rank: Frequent Contributor
timestamp: May 10, 2010, 12:01:18 am
content: Quote from: orbiter on May 09, 2010, 10:40:41 pmI am no expert in power supply design, but this sounds like the dumbest thing I've heard in a while. I have never seen a power supply that required such a "procedure" (not that I have seen many PSUs).BTW, just looked up on the TTi website and found this:Quote

author: Unknown
author_rank: Unknown
timestamp: May 10, 2010, 12:41:21 am
content: It's fairly common to have to short the power supply to set the current limit, since the meter only displays the current current. The better ones do have a better solution, since this is a bit clumsy. As for 3A vs. 5A, extra power doesn't hurt, so everything else equal, I'd chose the 5A one (but it would be a low-priority feature for me). I've rarely needed more than a few hundred mA. This is highly dependent on your application, if you're into power electronics (eg. motors, lighting, power amplifiers), you might need the 5A.

author: orbiter
author_rank: Frequent Contributor
timestamp: May 10, 2010, 04:00:53 pm
content: Great, thanks fellas. I just didn't want to go for something that wasn't the norm, or seemed extremely weirdRegardsorb

author: saturation
author_rank: Super Contributor
timestamp: May 10, 2010, 10:05:42 pm
content: In many of today's electronics, power consumption is minimal. In most designs, most voltages are way under 12V, 1A.What I find most helpful is the voltage adjustment available on many smaller PSU most to test a design's suitability for battery power under different conditions, without a DC-DC converter or as a test input for a device, rather than using it to power a prototype.

author: orbiter
author_rank: Frequent Contributor
timestamp: May 10, 2010, 10:20:41 pm
content: Thanks saturation for your input, I did bear that in mind when considering a psu, and made sure that the one I chose would do the low end as well as having the option to go up as high as 30v/5A max. So all should be well I hope.Regardsorb

author: saturation
author_rank: Super Contributor
timestamp: May 11, 2010, 01:14:13 am
content: Happy to help. If you envision you need 30V/5A somewhere in your design, that couldn't be a more clearly defined spec. There are so many options so long as you don't need a programmable supplyhttp://www.powersupplydepot.com/viewallpict.asp?dept=2&main=2Quote from: orbiter on May 10, 2010, 10:20:41 pm