Electronics > Beginners
Power supply advice please (I live in the UK)
CJay:
--- Quote from: bd139 on December 07, 2018, 02:21:17 pm ---Warning on the Farnell supplies. The E/LT ones are missing a couple of essential diodes, one across the pass transistor and one across the output. If you charge up an SLA with one and the line power goes out, or connect a voltage source to it by accident the wrong way, you'll need to buy new pass transistor and driver. Also the push button switches on the E series wear out. Otherwise they're really nice. I use an E30/2 as a radio supply occasionally for low power stuff that is tested and doesn't need current limiting.
--- End quote ---
Hehe, I found that one out the hard way :)
bd139:
Me too :-DD
nfmax:
--- Quote from: bd139 on December 07, 2018, 02:21:17 pm ---Warning on the Farnell supplies. The E/LT ones are missing a couple of essential diodes, one across the pass transistor and one across the output.
--- End quote ---
That's odd - are you sure? I have a couple of these, one L30-1 and one LT30-1. The circuit diagram, issued 1979-07-28, shows 1N4003's in both places, D202 & D203. Maybe it was missing in earlier incarnations of the design? Mind you, a 1A diode is a bit wimpy for a 1A supply, especially when they use two paralleled 2N3055's as pass transistors.
Nice supplies, and the only ones I have at present that go up to 30V.
cdev:
If you live in the UK, I would seriously consider looking - no making it your goal to buy one of the better UK made power supply brands (like TTI or Thurlby/Thandar) used.
If you do your research you'll get a much better supply value than one you buy new, one that would likely be built to last.
Also, being in the UK a similar situation likely exists to the situation here for US equipment, there is more of it on the used market there, so perhaps a bit cheaper.
james_s:
Used is definitely a good route for power supplies, I've built most of mine, but the commercial units I have I got used.
That leads into another point, if you keep at this electronics stuff you will likely accumulate multiple power supplies, so don't worry too much about trying to find the end-all, be-all PSU right off the bat.
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