For reasons that will become apparent in a while, I got a pair (*) of boost power supplies from the usual eBay source, allegedly capable of boosting a 10-to-32 VDC input to a 12-to-35 VDC output, up to 10 A and 150 W:
Boost power supply
After establishing that it would not produce 30 V into a 5.9 Ω load (5.1 A, but 152 W), I got systematic.
A 100 Ω resistor drew 1/4 A while I set the output to 28 V. Doubling up the resistors showed that it worked OK at half an amp:
Boost supply – 50 ohm load
Four 6 Ω resistors in series draw 1.2 A, then (channeling the true spirit of DIY 3D printing) two in series drew 2.3 A:
Boost supply – 12 ohm load
That’s 32 W each and, yes, they did get toasty, but, no, I didn’t leave them turned on all that long.
But a 6 Ω resistance still didn’t work, so the supply can’t provide 4.7 A at 130 W. In case you were wondering, that’s two 6 Ω resistors in series and a pair of those strings in parallel, so each resistor still sees 32 W.
In terms of driving the actual load, these supplies aren’t going to light it up.
Ah, well, whaddaya want for five buck from halfway around the planet?
(*) Davy’s Aphorism: Never buy only one of any surplus item, because you’ll never find another. Get at least two, maybe three if it’s something you might actually use.
#1 by Jason Doege on 2013-09-03 - 11:13
“…Get at least two, maybe three…” Because of this philosophy, my wife is considering submitting me to that show about hoarders.
#2 by Ed on 2013-09-03 - 11:27
I’m not there yet, but I can see it from here…
#3 by Red County Pete on 2013-09-03 - 23:01
I’ve convinced myself (and more importantly, Julie) that if I eventually use it, it’s not hoarding. It makes matters easier that we live a long way from suppliers and I have the ability to reuse random gubbage to make useful stuff. Whew!
#4 by Ed on 2013-09-04 - 07:54
And, if you keep it long enough, it becomes an heirloom!
In the case of tech stuff, it becomes uselessly obsolete. If you keep it even longer, however, it becomes a valuable antique…
#5 by Keith Neufeld on 2013-09-03 - 12:42
Would you be willing to share enough information to find the eBay source (by email, if you prefer)? If the specs and price are right, I have a heck of a use for this.
#6 by Ed on 2013-09-03 - 12:57
This will get you one: Or search eBay for dc boost 150W
Based on my very limited testing, the output regulation isn’t very good. I’d want to look at the output with a scope to see just how well / if that aluminum cap tamps down the spikes. For a bulk resistive load under, say, 100 W, it’s probably adequate, but …
#7 by Andrew on 2013-09-04 - 06:02
I buy three because I expect two of them not to work.
Of course, you could then say I should buy one at three times the price from a reputable supplier, but… they all come from the same place anyway.
Anyway, glad to know I’m not the only one.
#8 by Ed on 2013-09-04 - 07:50
I think you can definitely pay more to get parts from a better position in the sorting bins or, perhaps, parts that passed final inspection, all from the same factory. That’s as opposed to buying dirt-cheap crap on eBay that comes from their reject bins.
As nearly as I can tell, eBay is how Chinese factories monetize their scrap parts.
Despite what it looks like here, we actually buy quality stuff when it matters… it’s just that my toy budget has a tight upper limit these days.
#9 by madbodger on 2013-09-05 - 08:59
If I’m buying stuff for a specific use, I generally buy quality stuff so I don’t have to worry about it. When I’m buying things to try out, play with, modify, or just because they look like they might be useful some day, I generally buy the cheap stuff.
#10 by Ed on 2013-09-05 - 09:12
There’s a lot of that in the Warehouse Wing… [wince]