A small update:
I just tried a switchmode power supply rated 12V/2A for a 2GB EspressoBIN with a 3.5″ WD Blue disk.
The WD Blue disk draws 0.65A on the 5V supply and 0.5A on the 12V supply.
The board boots up fine, but if I log in via SSH and log in via the “serial” console, then as soon as I log out from the “serial” console, the board freezes.
Various other combinations result in the same thing. Logging in via SSH twice causes the board to freeze.
If disconnecting the harddisk this does not happen.
-So I expect that my 12V/2A switchmode power supply does not really make 2A available to the board.
It’s very likely that there is a voltage drop as soon as I start drawing a little extra current.
Thus I’d recommend either an old power-hungry iron-core PSU or a switchmode PSU rated for much more than 2A.
One more thing: I will not recommend powering the board via the LP4 Molex connector.
The reson is that the DC-jack works both as a power-inlet and a switch. It will switch the 5V DC power supply from the micro-USB connector off, and use 12V on the same circuit instead. This power is fed into the buck-regulator that generates 5V. -So do not use an ATX PSU directly with the LP4 connector or you might fry components on the EspressoBIN and maybe even your USB port on your computer if you’ve connected the serial cable.
The LP4 connector is really a mistake!! First of all, male plugs must NEVER supply power.
-Imagine that you have 110V or 240V prongs sticking out of the wall everywhere in your house.
Aside from the risk of electric shocks you’d get very often, the risk of short circuiting two prongs would be very high.
Male plugs are made for receiving power, female plugs are made for supplying power.
A few other reasons that the LP4 plug is a mistake:
The entire board contains very fine components. The LP4 connector will often require a lot of force to disconnect (and even to connect). Aside from that, the LP4 connectors are usually of such poor quality that they’re difficult to mate and it can result in damaging either the male or the female connector.
My recommendation is to not use the LP4 connector at all, but power your harddisk from an external PSU completely.
For instance, Mean Well RPD-60A would be great for a single 3.5″ drive – use a separate PSU for the board.
RPD-60A can be built into a 1U rack casing and can be purchased from Farnell/Newark/Element14: 2815574 or RS: 644-7203. It’s medical and IT-Equipment approved, plus it has all the certifications for being used world-wide.
I’ve even considered desoldering it (like I desoldered R48 on both boards to get rid of the too-bright LED light).
One connector that *could* have been used instead of the LP4 connector, would be a female SATA power connector.
Those are made for PCB-mounting and come in SMT variants. They’re widely used for backplanes and USB docking stations.
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