I want to buy a regulated DC Power supply, I searched around in my local stores and I only have two options left (based on what I need and what I can afford).

Triple Output 0-30V & 0-5A

Triple Output 0-30V & 0-10A

The difference in the price is 1350EGP, which is a 50% increase in the price of the 5A model. I do not know if it is worth it or not. So my question is, what are the experiments that I would need a current that is greater than 5A at home?

Note: I am not a newbie in electronics, I already have an oscilloscope, a function generator and couple of DMMs, I know my way around microcontrollers, analog electronics and digital electronics, above all that I already built a 1A linear DC power supply, but so far I did not use anything beyond 3A (supplied from wall adapters).

If by any means you would like to check the specifications yourself, here are the links to the power supplies.

  1. 5A version https://ram-e-shop.com/product/ps-rxn305d-ii/
  2. 10A version https://ram-e-shop.com/product/ps-rxn3010d-ii/

Thank you all in advance.

  • \$\begingroup\$ Those are incredibly cheap power supplies, are you sure you want to trust them? \$\endgroup\$ – Hearth Mar 28 at 20:51
  • \$\begingroup\$ 5A more is needed in long Led strips, testing DC/DC, motor aplications - especially those low voltage e-scooter types, charging big battery packs \$\endgroup\$ – Michal Podmanický Mar 28 at 20:58
  • \$\begingroup\$ @Hearth, unfortunately this is what is available in my country, if you have other suggestions please share with me I am open to anything. \$\endgroup\$ – Abd-AlRahman Muhammad Mar 28 at 21:21
  • \$\begingroup\$ @MichalPodmanický, what do you mean by testing DC/DC? \$\endgroup\$ – Abd-AlRahman Muhammad Mar 28 at 21:23
  • \$\begingroup\$ Are you aware of DIY variable DC power supply kits? You can build your own 0-~30V ~5-10A variable power supply from one fairly cheaply. For 3 channels you'd have to build 3 of them though. If they perform well those PSUs are pretty reasonably priced. If you just need one channel to get you started for hobby use though the kits might appeal to you. Assembling one is a beginner level task although there is need for some line voltage wiring. \$\endgroup\$ – K H Mar 28 at 23:01

The ones you're looking at look like pretty good deals to me as a lower budget hobbyist. They probably won't have the load regulation and protection characteristics of lab ones, but if they're modernized designs, they're probably very efficient and reliable compared to mine without being so extremely expensive as a lab supply. Shopping questions are prohibited, but I think it's fair to ask in a general sense how the power limitations of a PSU might work out for you assuming the supply lives up to them.

5A at 30V gives you about 150W to work with, 10A at 30V gives 300W. Less for properly simulating inductive loads, although for testing a motor the current limiting is usually useful up to its full rating, for testing a circuit that drives a motor you don't want to be either helping it out by limiting startup current or causing unrealistic brownouts in other parts of the circuit (Because most real sources droop rather than limiting current this way). RC land vehicles and large quadcopters or DC compressors are examples of high power motor load systems that might test the limits of the converters you're looking at. Motors are 80-90% efficent, so for just running a motor to test it assuming 80% efficiency, and that you found actual 5A and 10A 30V motors, you could test a 150W / 0.16 hp DC motor with the 5A supply or a 300 W / 0.32 hp DC motor

For LEDs 150W is a lot, probably the highest power single LED you'd want to play with would be 100W, which is silly bright, but your lesser supply would be capable of driving with a boost regulator. Then again a modular high power RGB driver could see surges of 3W per LED "pixel", so even an array of 100 for a sculpture might have peaks of 300W.

For processing loads, 150W is a lot.

Audio loads can be arbitrarily high.

For heater loads, you could plausibly want a very high wattage, for cooling loads even more so, but compressors have been mentioned.

If you use voltage converters, you'll lose 5 to 20% of that power in conversions (As little as 2%, but I'm not sure that can be done without an engineering degree), but you'll have the remaining power available at whatever voltage you want, within reason. Chances are you are really planning for one source voltage for most large projects and you need converters anyway. This is the model I usually use. I use the voltage supply to simulate a battery voltage and build whatever I need for the circuit off that. Last thing I breadboarded was an attempt at a driver for a 100W LED. I used 12V input with a 5V control circuit to drive the LED at 36V through a boost converter. I managed to drive the LED at about 20W because of limitations of the inductor I chose, and for the boost and cuk topologies I built, input current is continuous, so it won't set off your current limit until you get very close to it.

If you're trying to build a buck or buck/boost or any type that has discontinuous input current, the wattage you can make use of will be lower unless you filter the input to reduce current surges. If the filter is efficient enough, this will help you squeeze efficiency when you switch to a real battery. If it is not, you're better off without it in the end device, in which case you'd be better off with a supply that can simulate the current surges a battery can supply.

If you're wanting to design a boost driver your wattage is limited by the input voltage you want to simulate. A single Lithium-ion cell voltage of 3.6V gives you 18W to work with at 5A or 36W to work with at 10A. You could get around this by adding a voltage converter, but it's less convenient.

  • \$\begingroup\$ More than an amazing answer, I think I will go with the 10A version, so I can have more options, I am not an expert but I am not a newbie too, so I have plenty of stuff to try. Thanks alot for your time and great answer. Thank you all indeed. \$\endgroup\$ – Abd-AlRahman Muhammad Mar 29 at 7:18

I'm not a hobbyist but an engineer who works in power delivery. I don't think you should approach the question from the perspective of the current. It's called a power supply after all. So your question should be framed instead as "How much power would I use in my projects"?

You're basically choosing between a 150W and a 300W power supply. Will you every need 300W? Depending on the hobbies you're into you might! I will omit certain other things to look for like load line of the PSU and ripple under load and so on because these are the same supplies from the same manufacturer with the only difference being their power rating.

Hope that helps!

  • \$\begingroup\$ Great answer and great perspective, thank you for addition, it helps alot. \$\endgroup\$ – Abd-AlRahman Muhammad Mar 30 at 1:38

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