Hi,

oh my gosh, I just wanna purchase a dual output power supply, now I see some that are marked LINEAR or SWITCHING. Which one is better?

Thanks

Lisa

 

Linear power supplies will be heavier, and give off more heat.

Switching power supplies may give off more electrical noise.

 

Switching power supplies are much more efficient (80-90%) compared to 40-50% for linear. I would purchase a switching power supply. Linears are simpler, easier to work on and build. But if your purchasing, go with the switching.

__________________
"Remember, you're special.....just like everyone else."

 

It really depends upon whether you will ever be working with analog circuits. Switchers usually have more high frequency ripple on the DC which can adversely affect some analog circuit operation. I work in electronic design and all the bench supplies at my workplace are linear because of their low noise. You generally go with switching supplies only if efficiency is your first consideration, such as with battery powered equipment.

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Carl
Curmudgeon Elektroniker

 

actually in mfg efficiency is the law or soon will be depending on where you live.

Most countries are on their way to requiring, if they do not already, PFC and sub 1W standby on ALL consumer goods.

 

Hello there Lisa,


The kind of power supply you purchase should be matched to the application.

If your app needs low electrical noise then you usually go with a linear, but
if you need high efficiency (usually associated with higher power levels)
then you go with a switcher. If you need both, you go with a power supply
with a switching front end and linear back end, but this would be more
expensive too.

Also, if you could take a minute to describe your application (as much detail
as possible) it would make it possible for people here to make a much better
recommendation.

 

That's true and most switched mode power supplies and indeed linear power supplies have a poor power factor.

I don't think that all appliance will have to have power factor correction, just appliances over a certain VA rating.

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I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

 

Of course your application is what you will need to consider when purchasing a new power supply. One issue which is often over looked is the power supply's characteristic "surge impedance". You will find that a linear power supply will far out perform a switcher.
Why would you be concerned with the surge impedance of your power supply? If your application requires you to have full power at the rated voltage output instantly at the moment a load is applied or you turn on the switch, then you will want a linear power supply. If a few milliseconds delay is not a problem for you, than I think I would choose a more efficient switch mode power supply.

 

Tektonix has been using switching supplies in their best laboratory and portable scopes since around 1971 and have never had problems with junk on the lines. The HF switching transients and other artificacts are easier to filter out with much smaller components than you need to get rid of 60 Hz "hum" in the older supplies. In their lab scopes, it was still a combination of switchers and "linear" (analog) regulators. They had power supplies with supurb regulation and ripple specs as well as being very accurate in voltage.

Dean

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Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

 

That's true, many switching supplies are hybred regulatorsa which use a switching pre-regulator before a linear which improves the transient response and gets rid of the noise.

__________________

I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.