Products > Test Equipment
Power Supply: Build or Buy?
nctnico:
--- Quote from: Fungus on May 05, 2023, 06:26:58 am ---
--- Quote from: nctnico on May 04, 2023, 10:07:25 pm ---No. I own and have owned quite a few of the high-end HP switching PSUs and none of them have a really clean output.
--- End quote ---
I see the noise nannies are out again.
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No, just common sense. I read: beginning with electronics. A linear Korad PSU costs about the same as a switching PSU. Due to the lower noise, the linear PSU is a much more versatile piece of equipment.
Caliaxy:
--- Quote from: br4n_d0n on May 04, 2023, 07:29:49 pm ---The general consensus thus far seems to be for purchasing a power supply as there seems to be a lack of good info or kits out there for a beginner such as myself. However, if someone could find a really nice kit or great tutorial for an absolute beginner, I may take a look.
So, any recommendations for one $100 or less?
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For general use, I'd get a linear triple power supply, with +/- 0-15V for circuits that require differential power (e.g. op amps) and +5V (for logic circuits).
This kit on Amazon seems basic but OK. It provides everything you need, including transformer and enclosure, for under $80. You have to solder it yourself. Some users improved it over time (with multi-turn pots for finer voltage adjustment and output meters - read the reviews). It doesn't limit the current output, so you have to be careful. I have no experience with it.
https://www.amazon.com/Elenco-Triple-Output-Power-Supply/dp/B0002DT0GU/ref=sr_1_1?crid=1XLLSDE54UER8&keywords=elenco+triple+power+supply&qid=1683309302&sprefix=%2Caps%2C207&sr=8-1&ufe=app_do%3Aamzn1.fos.006c50ae-5d4c-4777-9bc0-4513d670b6bc
If you are in US, you might find good deals on older HP triple power supplies on eBay, such as 6326B (if under $50) or (better) E3630A (if under $80-100). Make sure they are in good shape (working, with no missing knobs and/or broken posts). I used an E3630A for a long time and was happy with it. It's nice to be able to limit the current, to protect your circuits from yourself.
If you buy new, Korad KA3005D (~$110) is a more modern option (well regarded here), but it's only single output. I have one of these too, no complaints.
I wouldn't power my soldering iron from a bench power supply either. I'd buy a switching power supply for everything requiring high voltage/power output. Safer and simpler.
james_s:
My most used power supply is a switcher based 1.2-30V that I built myself out of a cheap module and a surplus power brick, it's convenient because it's a tidy little enclosure that I can carry around wherever I need it. Next is an old Heathkit linear triple bench supply, it's a bit lacking in terms of features, it doesn't have current limiting but the variable outputs are only good for 500mA so this isn't much problem in practice. I like it because it has real analog knobs that respond instantly. I also have a big Tektronix bench PSU which is linear with digital controls, it's very capable but the user interface is pretty terrible, it's the only power supply I've ever had to read the manual to figure out how to use it. There are too many cases where the same button does multiple things. The linear supplies I have are much cleaner than the switcher, but at least 90% of the time it doesn't matter for what I'm doing.
br4n_d0n:
--- Quote from: Caliaxy on May 05, 2023, 06:33:36 pm ---If you are in US, you might find good deals on older HP triple power supplies on eBay, such as 6326B (if under $50) or (better) E3630A (if under $80-100). Make sure they are in good shape (working, with no missing knobs and/or broken posts). I used an E3630A for a long time and was happy with it. It's nice to be able to limit the current, to protect your circuits from yourself.
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These are stupid expensive right now on "theBay" for beat up and non-functioning ones... I don't get it. :palm:
nctnico:
My biggest problem with the old PSUs is that these don't have accurate readouts. Nowadays a lot of circuits run from low voltages. For that you need at least 2 digits after the decimal point. 3.3V chips (for example) often have maximum operaring voltages of 3.6V. You can't adjust the voltage accurately enough using a moving pointer on a scale that goes to 20V / 30V.
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