Yet Another Cycling Forum
General Category => The Knowledge => OT Knowledge => Topic started by: Wombat on 29 April, 2018, 11:34:56 am
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I've got a fixed voltage (12v nominal) power supply I acquired from somewhere ages ago, but I need a variable voltage supply to output up to about 20v, at a maximum of about 2A. This is for test running battery powered garden railway locomotives, and for assessing what speeds I get at what voltage (and verify what current they require), to finalise control and battery requirements for the finished article. Is this: https://www.amazon.co.uk/ECO-WORTHY-Adjustable-Variable-Digital-Switching/dp/B018QQ0W48/ref=pd_lpo_vtph_60_tr_t_2?_encoding=UTF8&psc=1&refRID=990B3E4BM2NHVS94XAGX OK?
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For a few quid more you can get one from Farnell, which would be my preference.
http://uk.farnell.com/tenma/72-2685/bench-power-supply-1-ch-30v-3a/dp/2563981?st=power%20supply%20bench&MER=mktBestSellerA (http://uk.farnell.com/tenma/72-2685/bench-power-supply-1-ch-30v-3a/dp/2563981?st=power%20supply%20bench&MER=mktBestSellerA)
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The greatest failing of my bench supply (an enormous 5A dual-output one from Rapid that I scored on eBay) is that it has grotty single-turn pots for the entire voltage and current range, making it all too easy to apply excessive voles through cack-handed knob-twiddling. (I keep planning to replace them with good quality 10-turn ones, but since I'd need to dismantle things to get the physical dimensions, I never have a round tuit.)
The one Diver300 links to appears to use encoders with a coarse and fine mode, rather than pots, which seems like a good idea.
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Aha, I knew it would be worth asking folk with practical experience of them, the risk of over-zealous twiddling overdoing the voltage, was not something that would have occurred to me, but makes perfect sense. The one Diver referred to, actually has one really basic useful advantage over the one I spotted, its got a bloody handle on the top!
I'll order that one, as I'm in "order things online from new companies" mode, having just ordered two 3600 lumen LED floodlights from a new (to me) company. No, I'm not trying to vapourise my retinas, the new Wombat burrow does have a dirty great barn attached to it, and its currently got a single 60w incandescent bulkhead fitting in it. As I'm starting to build a workshop inside the barn, I need to be able to see what I'm doing in there. The fun bit is that the roof is about 4.5 metres up, and I now only have a 4m metre long ladder.
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Given the size of the Amazon one, the whole thing can be gripped with one hand, so I'm not sure that the lack of a handle would be a big deal.
For the barn, I would guess that anything would be an improvement over a 60 W bulkhead fitting.