Power supply for beginner? - Page 1
Forum section: electronics / testgear

author: live2fish88
author_rank: Regular Contributor
timestamp: August 10, 2024, 11:39:51 am
content: Hey guys, looking for a DC benchtop power supply. I do a lot of 5v & 12v diagnostic (vehicles) as well as battery charging, 6v, 12v. I'd like to be able to power electronic devices on the benchtop (was repairing a cheap RC car for my son the other day and had to keep plugging and unplugging the battery). On the amperage side of things, i'm not so sure what i'd need. I'd think 12-16v would be plenty. What runs at 30v? I see a lot of cheaper power supplies running at 30v. I was looking at the Siglent SPD1168X but was unsure if there was better for the money. Also unsure as to why you'd want two channel, 3 channel, 30v, less amps, etc?

author: ledtester
author_rank: Super Contributor
timestamp: August 10, 2024, 02:24:52 pm
content: $200 is a lot to pay for a battery charger - I would consider just getting a dedicated unit.For your electronics power supply I would start with an old laptop power brick and a "buck converter module" like one of these:https://www.amazon.com/TKXEC-Adjustable-Converter-Regulated-Laboratory/dp/B0D6VCJZQY/https://www.amazon.com/Converter-Regulator-Adjustable-Regulated-Laboratory/dp/B0978T3JKH/https://www.amazon.com/Converter-DROK-Regulated-Adjustable-Regulator/dp/B098347BD9/https://www.amazon.com/DC-DC-Buck-Boost-Converter-Adjustable/dp/B0D5FNPTJS/If you find that you need higher than 16V or power with less noise then you can spend more money.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 10, 2024, 02:27:16 pm
content: ~30V is pretty standard for a bench power supply. Sometimes you'll see lower voltage with higher amperage, but that's typically how it works. Choose what you need: higher A, or higher V.My first bench PSU was the tekpower TP3005P:https://www.amazon.com/gp/product/B06XCQN82X/It's good for what it is, and 30V with 5A is nice. I got a good deal on and SPD3303X, and that's the only reason I stopped using the tek.Multi channels are nice. One thing you can do is to place them in serial or parallel to increase your output V or A. Or, you know, power multiple devices.

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 10, 2024, 03:04:11 pm
content: There're plenty of affordable 30V 10A PSUs in Aliexpress for about $50.Might not be the best, but unless you're running laboratory equipment, will do the job just nice.For example, the WPS3010H:www.aliexpress.com/item/1005003151034729.htmlA pretty complete review:

author: BeBuLamar
author_rank: Super Contributor
timestamp: August 10, 2024, 03:34:46 pm
content: For general electronic testing 0-30VDC 5A is sufficient. If you want to work on automotive stuff I think you need to get a fixed 12V (13.6-14V) high current power supply as a lot of the automotive accessories draw a lot of current.

author: nctnico
author_rank: Super Contributor
timestamp: August 10, 2024, 04:15:44 pm
content: A lot of the suggestions are switching PSUs (low weight is a typical giveaway). These are not suitable for use combined with doing measurements on a circuit as a switching PSU, even the high quality ones, push out way too much noise into the outputs and ground.IMHO a Korad KA3005 is a good place to start if money is tight.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 10, 2024, 04:39:13 pm
content: That Korad is similar to the Tekpower 3005 I mentioned. I think a lot of those are basically the same.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 10, 2024, 04:56:54 pm
content: Yeah, those korads 30V 5A or similar are fine. They're cheap, but they do the job.You can get them with one knob and buttons (i prefer those), but also two knobs for current/voltage (i don't like those).For battery charging I would really recommend a dedicated charger, especially if the chemistry is not lead.If something is wrong with the battery, a psu will not stop.

author: J-R
author_rank: Super Contributor
timestamp: August 10, 2024, 11:07:11 pm
content: Essentially all modern consumer electronics devices run from switched-mode power supplies. So while linear could be recommended, it's not critical for every hobbyist task. From what the OP is stating and his previous post history, I don't think a linear supply is a hard requirement.It's mentioned frequently, but I didn't see it called out here: if you are going to charge batteries with a power supply, be sure to put a diode in between to prevent the battery from feeding back and blowing it up.

author: nctnico
author_rank: Super Contributor
timestamp: August 10, 2024, 11:14:20 pm
content: Quote from: J-R on August 10, 2024, 11:07:11 pmYou are seeing this wrong. As long as a device works inside its own case, a switching PSU is just fine. However, if you are going to make measurements, the noise will become a problem. Especially if you are going to use grounded equipment like signal generators and oscilloscopes. The cheap power supplies without proper filtering are the worst ones. Been there, done that.

author: J-R
author_rank: Super Contributor
timestamp: August 11, 2024, 12:10:35 am
content: Those may be valid points, but the circumstances will matter and as I mentioned I don't see the OP needing linear based on his historical posts.For a beginner I like the idea of a low-cost device rather than an expensive one. Less chance of a mistake being costly. If you get to a point later down the road where you just must have a $400 or $1,500 bench supply, then get one at that point.

author: nctnico
author_rank: Super Contributor
timestamp: August 11, 2024, 07:25:29 am
content: Quote from: J-R on August 11, 2024, 12:10:35 amAgain, a linear power supply doesn't have to be expensive. The Korad I mentioned earlier is in the $100 ball-park and can be bought from a local supplier. I have a couple of the cheap switcher PSUs as well. The ones branded Rek and Gophert are OK safety & construction wise but others can be quite unsafe where it comes to the mains wiring.

author: Phil1977
author_rank: Frequent Contributor
timestamp: August 11, 2024, 10:54:02 am
content: Regarding value/price I can recommend the Peaktech 6225A or its 10A pendant:https://www.peaktech.de/PeakTech-P-6225-A-Labor-Schaltnetzteil-DC-0-30-V-0-5-A/P-6225-AThey are hybrid regulators, having a primary SMPS with an attached linear post-regulator for more precise control. After around 10 years of use the voltages and currents are still +/- 0.5% and the ripple is better than most other power sources in a mixed digital/analogue environment.

author: ledtester
author_rank: Super Contributor
timestamp: August 11, 2024, 12:32:10 pm
content: Quote from: live2fish88 on August 10, 2024, 11:39:51 amI think you'll find that even with a lab supply you'll find yourself applying/removing power from a circuit via some sort of clip -- alligator clip or test clip -- or inserting/removing a wire into/from a breadboard. Power supplies usually take some time to turn on so they are generally left turned on for the entire session.There are supplies with a output on/off switch which you may want to consider, but even with those supplies you may find it more convenient to manually connect and disconnect power anyway.