Dock ports?

[_wb_]

 

12V makes sense to have not just for an eSATAp port, but also if you want to implement my idea of having some room inside the docking station to install standard desktop PC components, like a DVD writer, 3.5" hard disk, or whatever it is you want to use with your Pyra.

I personally see no need for this, and I currently can't imagine ED having any interest in it, but this may indeed be a valid point why having a 12V rail could be usefull

You see no need for being able to directly read and write CD, DVD, Blu-ray on a Pyra? Could be pretty useful for PlayStation or GameCube emulation, ripping music or movies directly on the Pyra, making backups, or whatever.

Or you could get a fast 3TB internal desktop hard disk for about 100 EUR, which could be quite practical when organizing your SD cards.

I think a Pyra docking station with one or two (empty) standard desktop PC bays (and a corresponding number of power cables and SATA cables) would be a pretty good idea. It's basically all that is needed to turn a Pyra into a full desktop PC (with a weak CPU and GPU, but that's OK for most use cases), if you attach a PC monitor and keyboard to it and put a big hard disk in it.

 

[WizardStan]

Anyway, that depends on what you call "cheap" DC/DC converters are in the range of 3-4€ (afaik)

Technically you can build a DC/DC converter with two resistors and a diode, literally 5 cents worth of parts, it's just not efficient, or effective, or in any way a good idea actually.

 

[TrashyMG]

They do sell laptop style dual power supplies that supply both 5 and 12 Volts I have a couple with Molex style connectors.

 

[Neelix]

They do sell laptop style dual power supplies that supply both 5 and 12 Volts I have a couple with Molex style connectors.

Good point.

- Neelix

 

[Grench]

12V makes sense to have not just for an eSATAp port, but also if you want to implement my idea of having some room inside the docking station to install standard desktop PC components, like a DVD writer, 3.5" hard disk, or whatever it is you want to use with your Pyra.

I personally see no need for this, and I currently can't imagine ED having any interest in it, but this may indeed be a valid point why having a 12V rail could be usefull

 You see no need for being able to directly read and write CD, DVD, Blu-ray on a Pyra? Could be pretty useful for PlayStation or GameCube emulation, ripping music or movies directly on the Pyra, making backups, or whatever.

Or you could get a fast 3TB internal desktop hard disk for about 100 EUR, which could be quite practical when organizing your SD cards.

I think a Pyra docking station with one or two (empty) standard desktop PC bays (and a corresponding number of power cables and SATA cables) would be a pretty good idea. It's basically all that is needed to turn a Pyra into a full desktop PC (with a weak CPU and GPU, but that's OK for most use cases), if you attach a PC monitor and keyboard to it and put a big hard disk in it.

Actually, if you want to go crazy, with the right hardware it can become a 32TB file server. Not a 12VDC rail excuse though as these usually have their own PSU.

http://www.neweggbusiness.com/Product/Product.aspx?gclid=CJS79sO48r8CFa_m7Aodc30AuA&Item=9B-16-111-167&nm_mc=KNC-GoogleBiz&cm_mmc=KNC-GoogleBiz-_-pla-_-RAID+Enclosure+%2f+Subsystems-_-9B-16-111-167&ef_id=UvVZwgAABHXcVB6C:20140801160342:s

For your dock-drives... My concern is that the space requirement will greatly increase the height and depth of the dock - but hey, it's a dock. Maybe have a dock expansion that clips onto the bottom of the dock with a pair of 5.25" drive bays?

 

[Silent-Hunter]

Anyway, that depends on what you call "cheap" DC/DC converters are in the range of 3-4€ (afaik)

Technically you can build a DC/DC converter with two resistors and a diode, literally 5 cents worth of parts, it's just not efficient, or effective, or in any way a good idea actually.

How? That sounds interesting.

 

[Silent-Hunter]

Actually, if you want to go crazy, with the right hardware it can become a 32TB file server. Not a 12VDC rail excuse though as these usually have their own PSU.http://www.neweggbusiness.com/Product/Product.aspx?gclid=CJS79sO48r8CFa_m7Aodc30AuA&Item=9B-16-111-167&nm_mc=KNC-GoogleBiz&cm_mmc=KNC-GoogleBiz-_-pla-_-RAID+Enclosure+%2f+Subsystems-_-9B-16-111-167&ef_id=UvVZwgAABHXcVB6C:20140801160342:s


For your dock-drives... My concern is that the space requirement will greatly increase the height and depth of the dock - but hey, it's a dock. Maybe have a dock expansion that clips onto the bottom of the dock with a pair of 5.25" drive bays?

You mean, a dock for the dock?

 

[WizardStan]

How? That sounds interesting.

(+) -~r1~-~r2~----- (-)
|
d-- output (+)
I think that was how it went. Very simple circuit. I had to use it years ago for a project I was rapidly throwing together: I needed 3v but all I had was a 6v battery pack.I forget the exact formula, but r1 and r2 are involved in a ratio of the voltage drop you need, I think it was really just r1 = r2 *v(out)/v(in), or the other way around.

This can only reduce voltage, obviously. It's highly inefficient because it literally wastes the excess energy, and it's not very effective because the resistors put a limit on the load of whatever is connected to the device: you can increase the limit by using larger resistors but then you're also increasing the amount of wasted energy, and you need to make sure your source can supply it.

 

[Silent-Hunter]

How? That sounds interesting.

(+) -~r1~-~r2~----- (-)
|
d-- output (+)

I think that was how it went. Very simple circuit. I had to use it years ago for a project I was rapidly throwing together: I needed 3v but all I had was a 6v battery pack.
I forget the exact formula, but r1 and r2 are involved in a ratio of the voltage drop you need, I think it was really just r1 = r2 *v(out)/v(in), or the other way around.


This can only reduce voltage, obviously. It's highly inefficient because it literally wastes the excess energy, and it's not very effective because the resistors put a limit on the load of whatever is connected to the device: you can increase the limit by using larger resistors but then you're also increasing the amount of wasted energy, and you need to make sure your source can supply it.

Thanks! I did not know you could do that!

 

[levi]

That's a voltage divider. v[out] = v[in]*r2/(r1+r2) - that is the voltage you get is that across r2 compared with that across the whole resistive chain, provided you don't draw any load. Power is lost through current flowing from + to - through the resistors, not through your circuit. You can minimise that by increasing the resistors but then any circuit you connect reduces the resistance between the central point and the negative dramatically, as it provides an easier route to the negative terminal that going through r2, and thus the voltage going into your circuit drops. Make the resistors smaller (but maintain the ratio) and the current going through the resistors is much greater than that going through your circuit, and the voltage doesn't drop nearly as much, but the resistors will be burning much more energy.


It's a pretty useless circuit as a power supply, but it's how almost all transistors are wired up, with the gate being driven by a divider - since the gate doesn't take much current compared to the base-emitter current, the voltage is pretty stable, and usable for switching the transistor on and off.

 

[Silent-Hunter]

Can you divide the voltage to a second load, instead of using the resistor? As in divide a 10 volt source to two 5 volt devices?

 

[WizardStan]

Ah, Levi has the details. Bigger resistors or smaller, I forgot the specifics, sorry. Point was just an aside that it was technically possible, just a really bad idea.

 

[spud42]

remember that R1+R2 is a constant load across the power supply . not very efficient. wastes power as heat .

in Nelix's idea you can simply add a 2N3055 transistor in a TO3 package to the 7805 in the TO220 package to get a 5V output with up to 3A current draw.

very simple circuit and a lot more efficient. the DC/DC converters however are the most efficient but you have to pay a lot more for that efficiency.  

 

[Silent-Hunter]

I'm asking if you can use just the diode to divide a load between two devices. As in use one of the loads INSTEAD of the resistor.

 

[levi]

Resistance = voltage * load. As the load of your devices varies, its overall resistance varies (as it's designed to be used with a constant voltage). Non-switching devices can be used to divide the voltage, such as incandescent light bulbs - and if you replace both resistors you just end up with two bulbs in series. If the bulbs are the same - i.e. with the same resistance - they'll divide the voltage evenly, and both run on half the input voltage. If one's a 20W and the other a 60W the 20W will have three times the resistance of the 60W one, and will get 75% of the voltage, the 60W bulb getting the other 25%.


I haven't seen diodes mentioned elsewhere yet, and I don't see how they help in this case to be honest. A diode has infinite resistance if reverse driven (that is if the pointy end of the symbol points at the positive), and if reversed from that position, lets current flow, albeit swallowing a bit less than a volt regardless of the current (for a silicon diode at least) - that's the theory anyway. They're used to stop a device operating incorrectly if you put the batteries in the wrong way round, and also in rectifying an alternating current into directional (albeit bumpy) current (where you'll see a diamond of diodes, connecting both DC terminals to both AC lines, but switching which one is connected to which DC wire at which point during the AC wave using the behaviour of the diodes).


Edit: Ah, I see stan mentioned connecting a diode to the point between the resistors. For a simple static load that's simply not necessary, but I guess helps cope with any inductance or capacitance in your circuit, and keep that current flowing through your circuit rather than back into the resistors up top.

 

[Silent-Hunter]

I don't really know all that much about electrical circuits, despite building them for years. But I do get what you're saying.

 

[spud42]

this is all you need for a decent cheap 5v high current PSU

Q1 is the current bypass any high current transistor will do...

 

[thatgui]

You see no need for being able to directly read and write CD, DVD, Blu-ray on a Pyra? Could be pretty useful for PlayStation or GameCube emulation, ripping music or movies directly on the Pyra, making backups, or whatever.

The desktop system I have at home has never seen an internal optical disk drive since I built it four of five years ago (and both laptops have one neither). There is just one USB-BluRay drive for the occasional need to rip a AudioCD or BluRay, that gets shared between all devices in my household - even the Pandora, but just because I wanted to know wether it works or not.I work in the IT department of rather small company ( ~100 people). While most employees use a thinclient to work, there are several dozens of notebooks (including the ones from the IT) that all got no odd anymore. If a odd is really needed, we have one USB drive sitting in the drawer, collecting dust 99% of its time.

While ODDs surely won't vanish from the market (like floppy disks), its importance in daily usage has declined a lot in the last several years and will continue to do so.

So yes I have personally, absolutely no need for it.

Or you could get a fast 3TB internal desktop hard disk for about 100 EUR, which could be quite practical when organizing your SD cards.

Which may be of interest for people that want to replace their desktop with it, less for people that just want to use the dock for quickly connecting the Pyra to a TV or the second input signal connector on the display they usually use for their normal (desktop) computing setup.I (again personally) have no need for that too, as most of the data lies on a NAS, and I'm forcing myself to put everything there. As I'm rather "messy" in terms of organizing the data I have. Putting a harddrive in the dock would leave me with four (instead of three) places to create a mess, and this one does not even give me a chance to clean it up, as easily as the others, as I don't have it with me all the time.

I think a Pyra docking station with one or two (empty) standard desktop PC bays (and a corresponding number of power cables and SATA cables) would be a pretty good idea. It's basically all that is needed to turn a Pyra into a full desktop PC (with a weak CPU and GPU, but that's OK for most use cases), if you attach a PC monitor and keyboard to it and put a big hard disk in it.

But you need to design these bays, which (at list I think they should) need metal inlays to provide enough durability so people don't start complaining that its getting more complicated to exchange the drive since they had to "push in the drive a litter harder" the last time.If you go for "free wiring", which is still a must for 5.25" odds and 3.5" hdds, you need to make sure the wiring is durable and that its easily reachable for the customer. How are these drive fixated in their position ? Etc.

These aren't hard to solve problems at all, but they need to be solved, which costs resources, which I don't see justified by the gain in functionality. ED may think otherwise, we will see.

 

[_wb_]

I think such bay(s) should be optional, as indeed not everyone will need/want it. It's something to take into account when designing the dock. Ideally everything is modular.