# Is it worth a variable current power supply?

#### Rufinus

Joined Apr 29, 2020
87
Hi everyone. I´m learning english, excuse me if I make mistakes.

I´m also learning electronics, and I love experimenting. I´m thinking about buy a switching power supply 0-48V and 0-10A. I can buy the power supply only with voltage regulation or with current regulation too, but much more expensive.

Is worth to pay the current regulation? Is it usually used?

Thank you

Kind regards

#### crutschow

Joined Mar 14, 2008
27,912
Is worth to pay the current regulation? Is it usually used?
Depends on the application.
What are you going to use the supply for?

#### Dodgydave

Joined Jun 22, 2012
10,062
It's better if you have current limit, as you can set the Maximum so as not to damage your project.

#### LowQCab

Joined Nov 6, 2012
1,185
It's always nice to be able to set the Current extremely low when you first power-up a new project.
This can help to prevent the unexpected releasing of "The Magic Blue Smoke".
It's also good if you have Big Capacitors to Charge-Up, by limiting the "Inrush Current".
.

#### dl324

Joined Mar 30, 2015
13,293
Is worth to pay the current regulation? Is it usually used?
It's a nice feature, but I rarely use it.

#### nsaspook

Joined Aug 27, 2009
8,778
I use it with manually reviving 'dead' Li-ion cells. You need both voltage and current limiting plus a safe place for the battery in case of an accident.

#### MrChips

Joined Oct 2, 2009
24,415
There is common misconception of what is a constant voltage, constant current PSU (power supply unit).
You cannot regulate voltage and current at the same time.

Both voltage and current control settings on the PSU front panel are limits. In other words the PSU will not supply voltage and current above the set limits. At every instant, either the voltage or current limit is reached. Which limit is reached first takes effect.

I would guess that for 99% of PSU applications you need constant voltage. Therefore, yes, most applications do not need current regulation. The one reason for having current limit on the PSU is to avoid seeing your project go up in smoke when there is a serious malfunction and there is no current limit on the PSU. You might have saved some expensive components if you had set a current limit.

#### WBahn

Joined Mar 31, 2012
26,398
Hi everyone. I´m learning english, excuse me if I make mistakes.

I´m also learning electronics, and I love experimenting. I´m thinking about buy a switching power supply 0-48V and 0-10A. I can buy the power supply only with voltage regulation or with current regulation too, but much more expensive.

Is worth to pay the current regulation? Is it usually used?

Thank you

Kind regards
Here's something that I have found to be true far more often than not -- if you feel the need to ask others whether you should get something, then that is a pretty strong indication that you probably don't need it. We geeks tend to be toolaholics and it is easy for us to convince ourselves that every gadget we see would be useful, so we have a marked tendency to go looking for justifications to get it when we can't come up with one ourselves. But the mere fact that you can't come up with one ourselves is a pretty telling indicator. I can't even count the number of tools I've bought over the years that I've ended up never using even once (and the much longer list of tools that I've bought that I've used exactly once).

It is unlikely that you will ever truly NEED to operate in constant current mode, but having the ability to do so increases your flexibility and how you can go about doing certain things, so it can be very useful. The question is whether it is useful enough to be worth the additional cost -- and that's something that only you can answer. Keep in mind that this probably isn't going to be the last opportunity you ever have to buy a power supply, so there is nothing wrong with saving the money now and then, as you get a better handle on what is useful to you and how much value that use has to you in terms of the cost you are willing to pay, you can always get another one that has an adjustable current limit. It's always handy to have multiple supplies and once you decide you want a CV/CC supply, you can start looking for a good deal on one and don't have to feel rushed to by the first one that comes along because you will have the CV supply to work with in the meantime.

#### MrChips

Joined Oct 2, 2009
24,415
The other point to consider is that CC limit is not costly to add to a PSU. Hence almost every PSU made in the land of cheap labour comes with CV/CC controls already.

#### nsaspook

Joined Aug 27, 2009
8,778
I use constant current mode control frequently because I need magnetic field strength control in circuits with very little resistance. The feedback from a Gauss probe translates to a current setting for coils that look pretty close to a dead short for voltage.

#### Rufinus

Joined Apr 29, 2020
87
Thank you very much. Ok, only with voltage control. Is it allowed to put links of shops to show you the power supply I´m thinking about?

#### Just Another Sparky

Joined Dec 8, 2019
228
Current control is nice depending on the sorts of things you do. A current limited power supply is generally more forgiving when it comes to experimenting and breadboarding. As others have said, you'll go through fewer spare parts and it's handy when dealing with large electromagnets or capacitors.

It's not the end of the world, but if we're only talking $10~20 extra on top of an e.g.$100 base price then "buy once, cry once" you know?

#### Rufinus

Joined Apr 29, 2020
87
Ok, Thank you

#### sghioto

Joined Dec 31, 2017
2,395
You can also build a simple current limit circuit added in series with the power supply.

#### Rufinus

Joined Apr 29, 2020
87
Yes yes, this is what I have thought. Buy one with voltage control only, and in the future, there is voltage and current controls for 30 or 40\$.

Thank you

#### BobTPH

Joined Jun 5, 2013
3,802
How did you determine your need for 48V and 10A? I have been an electronics hobbyist for 50 years and have never needed either 48V or 10A.

If you want to save money, lower your specs. 15V and 2A is plenty if you are just trying to learn electronics.

Bob

#### Just Another Sparky

Joined Dec 8, 2019
228
I have been an electronics hobbyist for 50 years and have never needed either 48V or 10A.
It all depends on what particular disciplines of electricity you deal with. If you play with nothing but microcontrollers or TTL logic all day then sure, 10 watts is probably all you'll ever need. But when you start working with power electronics like SMPSs, audio amplifiers, motor drives, storage batteries or restoring old antiques then your power requirements may jump an order of magnitude or two.

Some torquey DC motors for instance require tens of amps just to spin at idle. An Arduino will run off of a 9 volt battery for weeks whereas an E-bike conversion might take an hour to bulk charge at one kilowatt. And then you come across people who just have a blast playing with big power, e.g. Photonicinduction.

My point is your power requirements are unique to you and will ultimately depend on the particular things that capture your interest.

#### Rufinus

Joined Apr 29, 2020
87
Yes, motors and thak kind of things

#### johnshaw

Joined Nov 5, 2020
5
It depends on the application you are using.
I sometimes use it like if required then.

#### nsaspook

Joined Aug 27, 2009
8,778
When you need current limits.
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