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Electronics for power supplies

First, I apologize for being (almost) the hardware version of a "script-kiddie". I do want to learn the techniques involved but all of the electronics courses I've found work the wrong way around. They teach "this is what we have and this is what you can do with it" whereas my brain works in the "This is the problem, here is a solution and this is why it works." manner.

This is how I learned software but when you get it wrong you can start again without losing the magic smoke!

I have a 250ah, 12V battery bank, multiple DC devices requiring power and, eventually, several power sources for recharging. I also have several MC34063 chips and a few higher amp chips (somewhat optimistically as it turns out).

Firstly, is there a practical course online that is built around this?

Secondly (and probably extremely basic), if a device draws, for example, 3A is it self-limiting or do I need to put something between the source and the device too restrict the power?


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lemonie6 years ago
What do you need to power?
(self-limiting usually)

L
ImmortalSoFar (author)  lemonie6 years ago
Pretty much everything. I live in an RV and, since most of my electronic stuff is DC, want to run it off the 12V system rather than take the overhead of an inverter and transformer.
My 7A fridge runs directly off the batteries.
I have a 12V ATX power supply which needs a regulated 12V and probably needs another 12/5V source for extra peripherals.
My monitor runs internally at 12V, my laptop needs a 3A, 12V supply and my partner's needs 19V, 6.3A.
Then there's 6V for the speakers and 5V,2A for the USB hub.

Then I'd like to learn enough to make a charge controller and I acknowledge that this is a wholly different proposition requiring a broader skill-set than I currently have. The software is no problem but my electronics knowledge is extremely patchy. I know enough to know that a modular design could work, just not enough to know how to make it work - hence the question about the course.

Your ATX will be stepping down from above 12V with regulators, that might be tough. However, I think it less critical than the 5V lines in terms of regulation.

For low voltage use heavy-wires.

Charge-controllers and electronics tutorials I'm not so good at.

L
ImmortalSoFar (author)  lemonie6 years ago
I have to admit that having tried to get my head around a -12V power line, I broke down and bought one (although it does require a regulated 12V input). I still prefer to know why something works rather than just blindly using it, though.

That's precisely what I mean by back-to-front teaching. Trying to work from the theory to a practical use is a far longer journey than practical-to-theory.

By the way - what's with putting capacitors between the circuit and ground? Am I missing something fundamental? Does it just even out the current in the rest of the circuit or act as some kind of fuse?

[Edit:]
I did ask about merging different currents but it turns out that you can just connect them together with blocking diodes contrary to what I was told by a professional. I was already under the impression he didn't know as much as he would like to think but now I have to reassess everything he's ever told me.

Thank goodness for this site!
> what's with putting capacitors between the circuit and ground?
.  Those are filtering capacitors. They have a low impedance and shunt AC to ground.

> Does it just even out the current in the rest of the circuit
.  That's it!
NachoMahma6 years ago
> is it self-limiting or do I need to put something between the source and the device too restrict the power?
.  When working properly a circuit will "self-limit" the amount of current it draws (plug your source voltage and the device's resistance/impedance into Ohm's Law) ... however, not all circuits will work properly, which is why we have fuses and circuit breakers.
ImmortalSoFar (author)  NachoMahma6 years ago
Thanks - I think I can handle a fuse! I just wanted to make sure before I connected up my motherboard and... well, I'm sure you an guess my nightmare scenario.