12vdc to PStwo (slimline) ?

[Guest]

Ok, in irc conversation with Rinco he mentioned hearing that someone had no problem using a 12vdc transformer to power a slimline.

This is even though the transformer shipped with the slimline claims to output 8.5vdc (even though its probably an unregulated transformer and the output may very a bit).

12vdc would be cool. It would make the slimline extremely portable for use in things such as cars. Granted, its possible to find 9vdc transformers as well but especially for combining it with other 12vdc things such as small LCD panels I like the idea of running everything off 12v.

Does anyone have any comments / discussion as to why this might not be a good idea. In other words, why it might work, but still be dangerous ?

Granted, most devices have a certain tolerance. +- 10% is often a good rule but 12v to slimline implies a very wide tolerance. Is this normal nowadays ? Can experienced eletronics techs provide any advice ?

(the goal is a more mobile dev platform, hence why it is hopefully on topic ;)

[pixel]

This would mean the input power has good voltage limiters. Look carefully, there are some big capas, and indeed at least one voltage limiter (the little 3-legged component in the middle of the various capas). I can't see what is the other component nearby, but nevertheless, only the little voltage limiter you can see there should be enough. I can't confirm anything of course. I'd need detailled schematics of that part. Maybe I'll try to probe a bit next time I open my v12...

[pixel]

Okay, I've checked the board a bit. There are quite some large 8.5v lanes all over. So, it has to be more than a single voltage regulator in order to lower down the power to the various components. If wouldn't try it. Yet. :)

[pixel]

Oookay, there ARE two dc/dc chip somewhere nearby the EE, which can handle up to 20V as input, and outputs 4.5V

http://www.vishay.com/docs/72376/72376.pdf

The lines seems to be indicating that it goes thru it directly from the main power unit before doing anything else. So, I guess it should be indeed okay to have up to 20V as input. Maybe. Won't try myself. :)

[J.F.]

Given the same wattage transformer, the higher the output voltage, the lower the output current. If you use a higher voltage than the adapter the slimline comes with, you need to make sure it also handles the current requirements as well (higher power transformer).

[Guest]

Thanks Pixel! This is indeed most interesting.

Ok, I will try it out and let you all know how well it works. I *should* have some quality, high-amperage 12vdc transformers laying around. Maybe I should have kept my regulated 12v supplies for my old ham gear... *sigh*

It is worth noting that the slimline powerbrick is 8.5V/5.6A on its ouput. We are talking a little less than 50W here. A 12V brick should need to be able to output at least 4A to keep about the same wattage. Thats still pretty hefty. We don't know how much it really draws in practice, but maybe I can keep bugging rinco to test this... *hint* *hint*

[rinco]

Well, this information Pixel has provided is very encouraging.

[cory1492]

I dont know if this info is any bit useful, but I know in a auto the DC is usually around 14.5V, and I have seen with a multimeter that a 13.5V regulated power supply actually gives a VDC of 18V unloaded....

[pixel]

Ewwww, you want to plug the pstwo bare into a car ? :D I wouldn't do that straight, without at least some filtering between the car DC and the power input :P Say, some big capas, a few diodes, and fuses or so.

[Guest]

I dont know if this info is any bit useful, but I know in a auto the DC is usually around 14.5V, and I have seen with a multimeter that a 13.5V regulated power supply actually gives a VDC of 18V unloaded....

I read recently that it is impossible for a "regulated" power supply to remain regulated without a load. There is some minimum load required in order for it to maintain its regulation.

I am not expert in this one way or the other, so take the above with a grain of salt.

[pixel]

Ho and, I forgot to post about that; I still might be useful for other people as well. I did some current measures on the v12.

By powering it up with the normal 220v ac / 8.5 dc brick (which brick actually outputs 8.8v for me), when in standby mode, it drains around 75mA. When powered on, without any disc, and whatever the v12 does, it drains around 1.45A. When powered on, with disc spinning at constant gaming speed, it drains 1.65A. And when disc starts to spin or stops (changes speed that is), I've mesured up to 2.2A, (I retried several times) but my multimeter isn't really fast, so the peak can be even upper.

Note that I first measured with a faster multimeter (a power generator that is), and I could spot that the boot up sequence first drains around 0.5A during a quarter of a second, then go to 1A for another quarter of second, and finally hits the 1.5A limit of my power generator so that it shuts down after that :P I guess the different peaks are dependant on the various components powering up, like screen, or sound output.

Have fun ;)

[J.F.]

Thanks Pixel! This is indeed most interesting.

Ok, I will try it out and let you all know how well it works. I *should* have some quality, high-amperage 12vdc transformers laying around. Maybe I should have kept my regulated 12v supplies for my old ham gear... *sigh*

It is worth noting that the slimline powerbrick is 8.5V/5.6A on its ouput. We are talking a little less than 50W here. A 12V brick should need to be able to output at least 4A to keep about the same wattage. Thats still pretty hefty. We don't know how much it really draws in practice, but maybe I can keep bugging rinco to test this... *hint* *hint*

You didn't read my post - if you go with a higher voltage, you have to go with a higher power transformer because the current requirement remains the same. If the 8.5V brick sources 5.6A, the 12V brick has to as well. If you source less than that, you run the risk of not having enough current. In voltage regulators, if you run low on current, the regulator will fail to regulate the voltage and you run the risk of damaging components.

More expensive regulators will detect under-current situations and shutdown. Normal ones just simply drift away from the voltage they are supposed to be maintaining.

[rinco]

My testing has come up with slightly different results to that of Pixel...

With assistance, I have built a 9.5v regulated supply capable of
outputting 4A (I've tested it up to 3A). It powers the pstwo fine, as long
as no dvd is in the drive. The pstwo loses power when the dvd begins
spinning.

If the pstwo is doing 'nothing' (sitting in browser), it draws 1.9A.

I also have a 9.2v battery that supposedly has a limit of 2A. But it seems
capable of powering the pstwo with a dvd in the drive. I measure 2.7A
peaks. But I suspect this is inaccurate.

So... it would seem a 4A supply is not adequate, contradicting current
test results. When I get a cro I hope to get better results. edit: i'll also
redo my tests with and without video/audio

[pixel]

Note that I haven't tested without audio/video output :P I think I said it in the post... Anyway ^^;

And as I said, there's quite a big peak when drive spins, but I couldn't measure it. However, no go with 4A ? Whoa... hmm, sounds quite high.