DC power supplies (complete beginner question!) - Page 1
Forum section: electronics / beginners

author: Mr D
author_rank: Regular Contributor
timestamp: August 17, 2025, 07:08:59 am
content: Hi folks,Complete beginner question coming up!I need to produce the following DC voltages for an analog camera project:1.5 volt3 volt (x2)6 volt8 volt.My input will be 240v AC (mains).What components do i need to create the smallest and cheapest solution for this?So i mean everything, including the board, connectors, and box to put it in.I don't really understand what components i need to connect the AC to each DC module. Some kind of bread board? As you can see, I'm a total beginner!I'm not being lazy and asking for a list, i just mean what kind of components, because i see all kinds of DC power supplies online, but i don't know what type i need and how to safely hook it all up.This is a one-off project, so i don't need to make multiple examples.I'm in the Netherlands.Thanks in advance!

author: Sorama
author_rank: Frequent Contributor
timestamp: August 17, 2025, 07:19:28 am
content: Is this some student task/project?

author: Mr D
author_rank: Regular Contributor
timestamp: August 17, 2025, 07:20:28 am
content: Nope

author: Sorama
author_rank: Frequent Contributor
timestamp: August 17, 2025, 08:10:53 am
content: I’m always very not motivated to encourage people to do things they apparently don’t manage or potentially dangerous like playing with 230V.That said, have a look at this;https://www.ti.com/product/LM2575?utm_source=google&utm_medium=cpc&utm_campaign=app-bsr-null-44700045336317452_prodfolderdynamic-cpc-pf-google-ww_en_int&utm_content=prodfolddynamic&ds_k=DYNAMIC+SEARCH+ADS&DCM=yes&gclsrc=aw.ds&gad_source=1&gad_campaignid=8024648057&gbraid=0AAAAAC068F3M0ofOWYu3d9etxbCZOjdQS&gclid=Cj0KCQjw-4XFBhCBARIsAAdNOkuzqeuhJLBTjd-5XggeTDbWW9tdZnHrydPNb5N1f2VTQWSipp2tLiAaAtUQEALw_wcB

author: Sorama
author_rank: Frequent Contributor
timestamp: August 17, 2025, 08:18:52 am
content: Btw, if you would have tried (at least) googling this “how to transform 230v to dc”,then the very first hit would have answered you question.

author: Mr D
author_rank: Regular Contributor
timestamp: August 17, 2025, 08:31:19 am
content: Hi, the first hit (i guess you mean the youtube film) doesn't show how to bus the 240v to multiple DC converters.I need 5 DC outputs.I'd like to know how to get a practical solution for this that can be put safely in a box. Point to point soldering on a table doesn't seem like a very safe solution.

author: Ian.M
author_rank: Super Contributor
timestamp: August 17, 2025, 09:01:19 am
content: Explain "3 volt (x2)"! Why cant you simply connect both to the same 3V supply?Do the various voltages share a common ground?How much current do you need at each voltage?How accurate do the voltages need to be?If you avoid working with mains, e.g. by using a plug-in 'wallwart' DC power adapter to supply low voltage DC to your box (at a voltage higher than any of the ones you need), then the problem reduces to mounting and wiring a bunch of DC-DC converter or buck regulator modules. Without mains in your box, safety reduces to making sure nothing can short out or overheat.*HOW* to wire low voltage safely depends on the max. currents required. For tens or even hundreds of mA, any point-to-point wiring hookup is likely to be adequate, or even mounting all the modules on stripboard. If you are dealing with tens of Amps, you are going to need proper terminals and probably bus bars for power distribution.

author: IDDLab
author_rank: Newbie
timestamp: August 17, 2025, 10:42:31 am
content: I absolutely agree with Ian.MAnd the cheapest and fastest solution could behttps://www.amazon.com/Adjustable-Converter-1-5-35v-Efficiency-Regulator/dp/B07C2QF1T1Of course before the converter you need some power supply, say 12V and how many amps are neededBut of course that depends on the question Ian.M asked you

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 17, 2025, 01:20:45 pm
content: Quote from: Mr D on August 17, 2025, 07:08:59 amOkay. Like Ian.M asked, How much current do you expect to draw per DC rail? What do you use each rail for?I would start with a Mean Well medical-rated class II isolated supply, perhapsGSM36E09-P1J. The device itself then just has a standard female 5.5mm × 2.1mm DC jack, center positive, for 9V ± 10% or 8.1V to 9.9V.(The rating just means that it will leak so little current through ground that you won't feel it if you touch one of the DC outputs while grounded. Of course, if you put yourself between DC+ and DC-, you may become part of the circuit.)For 8V, I'd use a low-drop linear regulator. For 6V, I'd use a linear regulator.If the 3V and 1.5V only need very little current (say, less than a hundred milliamps), I might use linear regulators for them too. Otherwise, I'd likely use a switching voltage regulator from 9V±1V to say 4V, and linearly regulate that to 3V. Depending on the current needed at 1.5V, I'd either use the same and then just linearly regulate to 1.5V too, or if more current is needed, use a separate switching voltage regulator to say 2.5V or 3V and linearly regulate that to 1.5V. To ensure no AC-DC switchmode noise gets into the rails, I might use a capacitance multiplier circuit on the input of each linear regulator.If you need the voltages for digital stuff like microcontroller or for operational amplifier rails, then I might use switching voltage regulators from 9V±1V to the target 1.5V/3V/6V/8V rails directly, because that stuff isn't very sensitive to power supply ripple or noise. It just depends on what you intend to power with those voltages.

author: Mr D
author_rank: Regular Contributor
timestamp: August 18, 2025, 10:56:55 am
content: Thanks so much for the help guys, I'm going to come back on this in the coming days.I don't yet have the knowledge to answer the "how many amps" question, apart from saying that all voltages need to supply what a battery produces (AA, 2x AA, AAA, PX28, and the 8 volt needs to replace a USB power source from a typical USB mains plug charger)This is the same converter, right?:https://www.amazon.nl/Binghe-DC-DC-Step-Down-Converter/dp/B0D7BWSTCX/ref=sr_1_9?__mk_nl_NL=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=3MZAUMC3J1BIB&dib=eyJ2IjoiMSJ9.JV71ztrjo6-cm1TosZvA56GMhoZ4ieAn1wP_sDQf8Stf7WD1VbFuf3l-t1LTnbIHDLEjtOFnCuA9E-3hYX9k3rcqQbNsvF6qOOMfNaJQ08p1ZHWvAPsGsf6HxUc2XmrjDbAPgI8UpjZSOIsn1qSbHtV9L1p2HetujmppG37U6CWXPuWUOaDOmGU2N-oSYX2_8Q6UdqgyU52YrGhsMRk7cPw1cSJrqdLNG4J7DQWVE_q_UWfLYZdBfeHtKV09GTxADhcGrMbJetglRGKa762cDqFzq5Ie_L5SQ5PyFnFhUwY.p37Mvls5YNraOh1Vqig5lMM_UpnD2zCx8s3tYK9V1Io&dib_tag=se&keywords=LM2596+DC-DC&qid=1755514435&sprefix=lm2596+dc-dc%2Caps%2C134&sr=8-9