Introduction: USB Menorah (AKA Chanukiyah)

This is a small desktop USB powered LED Menorah. There are lots of desktop Christmas decorations and gadgets, but few if any Channakah decorations. This is a simple low-cost LED array powered by standard USB port.

Step 1: Materials

You will need.
-9 LEDs (~$2)
-soldering iron
-solder
-USB pigtail cable (~$2)
-6" hookup wire
-pliers

LEDs can be assorted colors or all the same color, you decide. You can get LEDs from almost any electronic store like Radio Shack or online. Colors are a personal preference and dont really matter. I had some spare ones laying around, but next time I think I will use these cool Purple LEDs from Allied Electronics.

Step 2: Circuit Design

Standard USB output is 5VDC and can draw up to 100mA. We only need ~2VDC for each LED@30mA. Your mileage may vary depending on the LEDs you choose. Lucky for us there is a wizard we can plug numbers into that will help design the circuit for us. Use this LED wizard to help with your design - LED Wizard. I Chose a 2x4 array with 1 extra LED.

each 27 ohm resistor dissipates 24.3 mW
the wizard says the color code for 27 is red violet black
the wizard thinks 1/4W resistors are fine for your application
the 100 ohm resistor dissipates 90 mW
the wizard says the color code for 100 is brown black brown
the wizard thinks 1/4W resistors are fine for your application
together, all resistors dissipate 187.2 mW
together, the diodes dissipate 567 mW
total power dissipated by the array is 754.2 mW
the array draws current of 150 mA from the source

Step 3: Build the Circuit

Now that you have everything you need, solder it all together. Remember that the negative side of the LED is flat and typical has a shorter lead. Use the pliers to bend and cut the leads as needed. The leads will form the body of the Menorah.

I used the extra LED as the Shamash in the middle. I also used this LED as the base for where positive and negative lines join. I used insulated hookup wire to connect the positive lines together so they would not touch the negative lead, and soldered all the negative leads together as shown in the diagram.

Notice the difference between the diagram drawing and the actual photo (bad photo, I know) of where negative leads are soldered. By accident, I soldered the resistors for outside pair in series instead of parallel. While my circuit still worked, the outside pair was significantly dimmer than the others. Note to self... remember ohms law next time.

Step 4: Finish Up

Now that your array is all soldered together, finish up by soldering the USB pigtail. There are four wires plus a shield on the pigtail. The only ones needed are the Black and Red wires. The others can be cut back to insulation and ignored. Solder it all together and plug it in.

OPTIONAL --Just to be save and sure that I nor the little ones shock themselves, I covered mine with liquid tape that you can get at Wal-Mart or automotive store. The insulated hookup wire should be sufficient to keep you from shocking yourself and its not really needed. Five volts also wont hurt you if you do accidentally shock yourself, but my wife doesn't believe me.

You now have a USB Menorah (or Chanukiyah if you prefer) to sit on top of your monitor or desk at work.

My next idea is to submerge this into a Borax Crystal solution so crystals can grow on it. Maybe next year.


Comments

author
nodoubtman (author)2012-01-31

but don't forget usb are limited to 100 mA!! :(

author
nodoubtman (author)2012-01-31

really cool! :)
how many mA ? :)

author
marc.cryan (author)2009-01-05

That's really funny. I love it!