Hi all,

Going to be making a fusebox this weekend, just wondered if you brainiacs could take a quick look at the very simple diagram and let me know if there are any things you'd do differently or recommend I do.

Basically I have a 1A 12vdc wall wart/power supply and I want to plug it into a fuse box which will have an on/off switch, a power-is-on LED, and a 500 mA fuse.

The reason I only want a 500 mA fuse with a 1A power supply is because I will be using this little box for test circuits and won't need that much current, but the power supply could be any ampage above 500 - the last thing I want it to do is BE 500 and get a little warm. I aim to be using less than 400 mA anyway with this fusebox.

But I digress, here is the circuit, going to use a small project box, a DC jack, a rocker switch then a fuse on the negative, with nothing on the positive. Then a 350 ohm resistor and a red LED on in parallel with the two output wires. The fuses are 500 mA fast blow fuses.

This works OK in sim software.

The signal lamp is where the eventual load will be, with those wires being the red and black. I will be using 16/0.2 wire for the output wires - is this wise? I also have some 1/0.6 for breadboards but that may snap with flexing it..


I look forward to hearing your replies.

Thanks!

Adam

 

You might consider just putting fuses in your projects, and then you wouldn't need this box. This would allow you to protect each project with a fuse of the right size, instead of one-size-fits-all. On the other hand, if you want this box to protect the supply against a problem with one of your projects, that makes sense.

 

Well this little box will be the go between for when I'm using power on my workbench, in my projects I will have this kind of circuit internally, but for example when I'm testing something then I will use this, with an easy on off switch and safety fuse.

 

How about adding a 7812 regulator and some capacitors? (Unless, of course, the wall wart powersupply already has it. Guess it has...)

 

Thought about that, but then I have to worry about the heat and the power supply I recently bought (12v/1A) is regulated so no need I guess!

Once I am more proficient I'm sure I will create a variable power supply.

 

What are the spec's on D1?

 

regular red LED, so 2.0-2.2v, 20mA

 

looking at the picture, I did get the calculation wrong - I did it for a 9v supply rather than 12v, but last night when I wired it up I luckily did get it right and used a 470

 

looking at the picture, I did get the calculation wrong - I did it for a 9v supply rather than 12v, but last night when I wired it up I luckily did get it right and used a 470

That's what I thought...