LED Patio Umbrella Jar Lights

Step 3 Assemble the Lights

Now this is what you want the Helping Hands for. You need to solder the LEDs directly together. To do this, put an LED in either of the two crocodile clips, then position them so the legs are overlapping each other and the LEDs are right up against each other. What you end up with is a kind of arc of LEDs which works out really well in terms of light distribution.

Take special care with the orientation of the LEDs, there is a little notch on one of the corners indicating polarity. Or, looking into the side of the LED, the legs attached to the larger piece of metal inside the package are the cathode or "negative". The pins attached to the smaller piece is the anode or "positive". See the picture of the LEDs in the clips to really see what I'm getting at.

Once you've got your LEDs soldered into arcs of three, clip one lead of a resistor so it's just a little longer than the leg of the LED and solder the clipped leg to the free cathode of the LED arc. Also cut a length of single core wire so it's about the same length as the total length of the cut resistor and solder that to the free anode of the LED arc so you end up with the arc and resistor on two long legs.

I tested them all at this point. I had a 12vdc source to hand so I put them all into my breadboard's power rails and flipped the switch. Five minutes later when I fully regained my vision, I returned to work!

Now you need to identify which tab on the DC socket is the positive and which is the negative. I did this by inserting a plug that I knew was wired properly (a 2.1mm barrel plug with integrated screw terminals. Very useful things!), set my multimeter to measure resistance and just tested each tab on the socket.

The sockets I used have a third tab positioned opposite the negative tab. After having identified the positive and negative, I assumed that the opposite one was also negative... wrong. Not sure what's going on there, there was a smidgen of voltage on it so... yeah. Don't make that mistake.

Once you've identified the tabs, you need to take three LED arcs and feed all their anode wires through the positive tab. Then feed all the free resistor legs through the negative tab. This is a bit fiddly. My single core wire was thicker than the resistor legs making it harder to bend, so I did those first. The resistor wires were significantly easier to bend into place. Make sure that all the arcs are arranged as you want them before you solder those connections.

All that remains now is to drill an appropriately sized hole for your socket into the jar lid, mount the whole thing in the lid then ease the leds through the neck of the jar and screw on.

When that's done, give it a final test.