# Help with my LED multiple bulb circuit (beginner)

I will start by saying I've been researching how to create circuits for a few days coming from knowing nothing, so if anything I say sounds dead wrong I apologize.

What I'm essentially trying to do is create a small modular lamp containing 1 LED bulb per "block", and each block can be plugged into the previous adding more "nodes" to the lamp. I've created the basic circuit diagram and found the parts I would like to try to use and I was hoping you could tell me if it could work or if I'm way off base.

For the power supply I would use a 12 volt 2.0 amp wall wart. This would plug into the bottom of the first block via this 2.1mm barrel jack. From there onward each block will have the same barrel jack on the top of the block that can be plugged into via this 2.1mm male adapter at the bottom of each subsequent block. Inside each block I will be powering a single 12v 2watt LED.

I only want to power 5 of these blocks. Having my math checked at another forum showed that the 5 block at 2W each = 10W divided by 12volt = 0.83amps so even with some built in margin of error I'm under the 2amp from my power supply.

However, I read the tech specs of the barrel jack I linked and it says it has a rated current of .5amp. Is that per block (2W/12v=.16a) or is that for the whole setup meaning it can't handle my .83a?

Also I was wondering if there was any way to go about limiting it to just the 5 blocks? Assuming someone else got a hold of these plus some spares and plugged in say 8 blocks it would overheat and be dangerous correct? Is there a way to build in a shutoff past 5 mechanism?

I don't know how to use those fancy mockups I keep seeing so here is a MS paint rendering of what I'm talking about:

(the arrows are to indicate the direction the blocks are being plugged into each other)

Would this work?

• The 0.5A limit on each connector is due to a pre-defined temperature rise of contact area with margin for aging. You can use larger connectors and include a polyfuse in each module for short circuit protection and gross overcurrent or rely on a label warning. – Sunnyskyguy EE75 Mar 23 '17 at 20:02
• You can get the same size barrel connectors with a higher current rating if you search a bit. – Andrew Morton Mar 23 '17 at 20:03