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Post by ozohnoes on Dec 24, 2017 2:36:37 GMT -5
I am trying to trigger on a UPA-200. I have a Stealth DC-1 but it doesn't have a trigger output (sadly).
It's for my computer, so maybe even something off USB would do the trick? I've set my PC to power on when it receives power from the wall.
PS. Does the UPA-200 have an always on mode? That would work for me as well.
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Post by MusicHead on Dec 24, 2017 8:49:07 GMT -5
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Post by leonski on Dec 25, 2017 16:51:24 GMT -5
I just looked at the specs for the device linked above and they are impossible.
First? I don't think USB sinks any more than 500ma, 1/2amp
And with an input of 5v @1amp, you CAN'T get 12v at 1amp OUT. That's against the rules.
However, such a circuit as described, above is easily done. Just keep the 5v relay contact current rating to as small a value as possible (200ma would be fine) so it'll both drive the relay and have sufficient contact
current rating for the 12v part.
Using a relay with a time-delay feature (variable, usually) might not be a bad idea to help prevent turnon thumps.
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Post by MusicHead on Dec 25, 2017 22:21:08 GMT -5
leonski, yes, you are correct, when you boost voltage the output current is approximately the input current divided the boost ratio minus losses. So in this case, the output current would be about 1/3 of the input, as the output power can only be less than the input power, due to the conversion losses. However: - The Max current in the USB 2.0 specs is actually 900mA (bumped up from the original 500mA you mentioned) - Even assuming the worst case, thus a computer USB port limited at 500mA, the boost cable would provide around 150mA at 12V. I do not know the spec of the UPA-200 trigger, but I suspect that much current should be plenty for it. Building a relay circuit would sure be more fun, though 😁.
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Post by leonski on Dec 25, 2017 23:59:49 GMT -5
Not only 'more fun', but you could also provide for a 'time delay' feature, which means you could turn amps ON last and OFF first, which is generally considered 'good practice'.
Yes, I'm not 'current' with USB spec. Isn't it USB 3.0 which provides the higher current? And it's different for 'charging'.
The DC to DC convertor, is I think, a 'buck convertor', which my company, IR made in abundance.
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Post by Ruiner46 on Dec 26, 2017 12:32:31 GMT -5
Instead of doing something fancy with USB, you could just pull 12V from the PC's internal power supply to create the trigger. If it were me, I'd take an unused power connector for an extra fan, or hard drive and solder a cable with a 3.5mm plug to 12V and ground. If you can find an unused 4 pin molex connector, it would be pretty simple. They have 12V, 5V and two ground pins.
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Post by leonski on Dec 27, 2017 2:21:51 GMT -5
I just cleaned my den and found several of the molex / to  connectors used in PC builds. I don't know if the standard has changed, but these were what i used when I build my last PC. I even have an IDE cable, a SCCI 40 or 50 pin external cable, an ISA SCCI card and an AGP Video Card. If anyone wants to do a 'vintage' build. I even have a CD copy of Windows 95b and a few other OS. Anyone want any of that stuff, just say thw word. |
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Post by brubacca on Dec 27, 2017 9:41:17 GMT -5
Instead of doing something fancy with USB, you could just pull 12V from the PC's internal power supply to create the trigger. If it were me, I'd take an unused power connector for an extra fan, or hard drive and solder a cable with a 3.5mm plug to 12V and ground. If you can find an unused 4 pin molex connector, it would be pretty simple. They have 12V, 5V and two ground pins. Brilliant. |
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Post by copperpipe on Dec 27, 2017 9:55:49 GMT -5
You could buy one of these power bars controlled by USB. Plug the powerbar into your computer, install the software, and the computer can then turn on/off individual power plugs at will. www.pwrusb.com/ |
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Post by leonski on Dec 27, 2017 13:53:04 GMT -5
I like the idea, generally, but do NOT see any mention of surge suppression.
The active devices are CHEAP in the extreme and adding such to an outlet strip is not that much $$, even to the
end user.
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Post by cybergarou on Feb 20, 2018 18:24:19 GMT -5
I am trying to trigger on a UPA-200. I have a Stealth DC-1 but it doesn't have a trigger output (sadly). It's for my computer, so maybe even something off USB would do the trick? I've set my PC to power on when it receives power from the wall. PS. Does the UPA-200 have an always on mode? That would work for me as well. Easy, I have a cambridge audio cxn with no 12v trigger and an Emotiva XPA-2. I made a cable from an old USB cable to mono 1/8 and it worked perfectly for a couple of weeks now. Usually, 12v trigger accept from 3v to 12v so the 5v of the USB is working fine. No relay and no external transformer. |
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connectors used in PC builds. I don't know if the standard has changed, but these were what i used when I build my last PC. 
