power supplies

[orbiter]

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.html

Or 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_g

Or even one of these.. http://www.circuitspecialists.eu/triple-output-dc-bench-power-supply-lcd-display-csi-3003xiii-p-167.html

What are your thoughts please?

Thanks

orb

[Kiriakos-GR]

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 .. 

[armandas]

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=item2a0671955d
Smaller ones can be had for even less. Just keep an eye on ebay until you find what you need.

[orbiter]

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 great http://www.circuitspecialists.eu/triple-output-dc-bench-power-supply-lcd-display-csi-3003xiii-p-167.html plus it would have plenty of headroom for further experiments which would be great

regards

orb

[armandas]

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

[Kiriakos-GR]

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. 

[orbiter]

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

Thanks mate, I'll bear that one in mind whilst I'm looking around.

[orbiter]

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. 

Yes, 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

[alm]

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.

[orbiter]

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.

Yea 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 warranty http://www.circuitspecialists.eu/triple-output-dc-bench-power-supply-lcd-display-csi-3003xiii-p-167.html

[alm]

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).

[orbiter]

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).

Thanks for the info alm

One 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.

In CC mode the user may set the CURRENT LIMIT as desired up to the full limit of the unit. The current is set by the UP and DOWN buttons that are labelled "current-adj."

To set this variable current limit, connect a short (test lead or wire jumper) directly across the Power supply output terminals and then adjust the current limit value up or down using the buttons described. When the meter displays the desired current limit value, remove the short from the power supply and the unit will now be set as desired.

If you remove Power from the unit (or turn it OFF) you must reset any current limit value you previously had set. It will default to the maximum current value.

[armandas]

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).

Thanks for the info alm

One 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.

In CC mode the user may set the CURRENT LIMIT as desired up to the full limit of the unit. The current is set by the UP and DOWN buttons that are labelled "current-adj."

To set this variable current limit, connect a short (test lead or wire jumper) directly across the Power supply output terminals and then adjust the current limit value up or down using the buttons described. When the meter displays the desired current limit value, remove the short from the power supply and the unit will now be set as desired.

If you remove Power from the unit (or turn it OFF) you must reset any current limit value you previously had set. It will default to the maximum current value.

I 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:

With the output switch ‘off’ the current limit set point is displayed. With the output switch ‘on’ the actual output current flowing is displayed.
This invaluable feature allows delicate circuits to be protected by accurately setting the current limit level (down to a few milliamps if necessary) before connecting the circuit under test.

[alm]

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.

[orbiter]

Great, thanks fellas. I just didn't want to go for something that wasn't the norm, or seemed extremely weird

Regards

orb

[saturation]

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.

[orbiter]

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.

Regards

orb

[saturation]

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 supply

http://www.powersupplydepot.com/viewallpict.asp?dept=2&main=2

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.

Regards

orb