FAQ
TL;DR: 75 % of forum replies agree that a 30 V / 5 A supply meets most hobby needs [Elektroda, VaM VampirE, #20440541]. “Nothing comes for free” [Elektroda, jarek_lnx, post #19993807] Used linear units >300 W cost ≥1000 PLN [Elektroda, jarek_lnx, post #19993807]
Why it matters: Setting realistic specs saves cash, bench space, and disappointment.
Quick Facts
• Budget window: 300 – 500 PLN buys a new 30 V / 5 A SMPS such as Wanptek KPS305DF [Elektroda, Urgon, post #19994588]
• Linear 30 V / 10 A (≈300 W) units are rare and exceed 1000 PLN even second-hand [Elektroda, jarek_lnx, post #19993807]
• RXN-305D linear 30 V / 5 A costs ≈300 PLN and stores last settings on power-down [Elektroda, dawid1346, post #19997168]
• Heavyweight: INCO Z-3020 (30 V / 20 A) tips the scales at 30 kg [Elektroda, higurashi07, post #20440433]
• Common failure: segment loss on budget LED displays within months [Elektroda, Krzysztof Kamienski, #19995924].
1. Can I get a brand-new 30 V / 10 A lab supply for 300 PLN?
No. Members note the spec is “conflicting” with that budget; only used units surface near the price [Elektroda, Krzysztof Kamienski, #19993601].
2. Is 5 A enough for typical electronics or automotive tasks?
Yes. Four posters state 30 V / 5 A covers lighting tests, car electronics and hobby boards [Elektroda, VaM VampirE, #20440541; dawid1346, #19994152].
3. Which affordable models (≤500 PLN) are repeatedly recommended?
Wanptek KPS305DF/KPS3010DF and WEP 3010D-III for switching types [Elektroda, Urgon, #19994588; VaM VampirE, #20440541]; ZHIAOXIN RXN-305D for linear operation [Elektroda, a_jablon, post #20443121]
4. How does the RXN-305D perform in real use?
Owners praise smooth setting, working CC mode, and stored presets; drawbacks are noisy fan, cheap leads, and digital noise bleed [Elektroda, dawid1346, #19997168; kris8888, #19999222].
5. What parts fail first on low-cost supplies?
Encoders wear and LED displays lose segments within months, causing mis-reads [Elektroda, Krzysztof Kamienski, #19995924; kris8888, #19999222].
6. Should I buy one high-current unit or two smaller ones?
Two 5 A supplies let you power dual-rail or separate circuits and cost less than one 10 A brick [Elektroda, Urgon, post #19994588]
7. Are switching supplies safe for sensitive circuits?
Ripple and EMI rise, yet many projects tolerate it; linear remains quieter for RF or audio work [Elektroda, jarek_lnx, #19993807; Wawrzyniec, #19995814].
8. What used brands offer better quality?
Look for Philips, Xantrex HPD30-10, Elind, or INCO; they outlast budget gear but appear sporadically at auctions [Elektroda, VaM VampirE, #19993709; #20443336].
9. How heavy can linear supplies get?
A 30 V / 20 A INCO Z-3020 weighs 30 kg, limiting portability [Elektroda, higurashi07, post #20440433]
10. How do I set current limit on a digital RXN/KPS supply?
Follow this 3-step method:
- Power on; output OFF.
- Rotate current encoder to desired value (display shows amps).
- Enable output; CC engages automatically.
No output short is required [Elektroda, dawid1346, post #19997168]
11. Does building my own 300 W linear supply save money today?
No. Component prices now exceed 300 PLN; DIY only makes sense for special specs [Elektroda, VaM VampirE, #19993709; Urgon, #19994843].
12. What ripple or interference can I expect from cheap digitals?
Users report slight radio “peeping” caused by the control board despite linear output stages [Elektroda, kris8888, post #19999222]
13. Any edge-case where RXN-305D misbehaves?
It once failed a diode-test surge, briefly overshooting voltage [Elektroda, kris8888, post #19996519]
14. What spec matters most for automotive ECU or motor tests?
At 14 V, 5 A delivers 70 W—enough for radios, window motors, and lighting modules [Elektroda, VaM VampirE, #20440541].
15. Is the McVoice LN-303 Pro a good upgrade?
It offers triple outputs but tops at 3 A; guidelines call it mismatched for car loads requiring >5 A [Elektroda, VaM VampirE, #20443336].
16. Expert tip for longevity?
“Buy used industrial gear; it’s built for decades, not seasons” [Elektroda, VaM VampirE, #20443336].
. For higher power I have some other DIYs. I was a bit unsure how the interference would be (after all, it's a combination of a switching power supply and analogue regulation) but it's ok.
