I have a SATA HDD case (product details) with switches that toggle the power supply for each HDD.
My aim is to control each switch individually via software.
(My background: I'm a total novice to applied electronics, but I have a good grasp of the underlying physics.)
Luckily, it suffices to connect pins A and B (or any equivalent pair) to enable the HDD power supply as if the button were pressed. The top pins are ignored.
When a HDD is attached and the switch is off, the voltage between A and B is 12V. The current, when connecting A and B, is < 1mA.
My idea is now to add a transistor to each A-B pair of pins and route a wire from each transistor base to a microcontroller that's attached to the same ground potential as the HDD case. Is this approach feasible and safe?
Can you recommend a simple, low-power microcontroller that can be attached to a consumer motherboard, preferably via USB? It should have at least 15 output pins which are only needed to toggle the transistors.
The software interface that the MC should be able to implement is trivial:
set_pin_voltage(PIN_INDEX, on|off). Maybe a simple IC is enough?
What type of transistor would be appropriate? The default switch state should be off, so the transistor should only conduct when a voltage is applied to its base.
What type of cable would you recommend?
Since posting my original question, I've read a good amount of
The Art of
Electronics, but I nonetheless feel very insecure about real-life component
selection for my first electronics project.
I'd love to hear your expert advice.