For all ye jolly jews out there, here’s a sweet post made from one of our friends in Israel, Ori:
“I drooled over the microcontrolled mini led “menorah” by evilmadscientist.com
but figuring S&H to Israel and having to swallow my pride purchasing anything in kit form, I figured there must me a better (i.e. more complicated) alternative. Just in time for Hanukah 5768, I proudly give you the DIY electronic Hanukiah!
0. Using an LM3914 DIP-18 led-bar driver we shall build a geeky unkosher LED Hanukiah. The more you rotate the potentiometer, the more LEDs light up. Recommend adding 1 led “candle” per Hanukah day although that won’t make it any more kosher. The electronic Hanukiah will double as a variable nighttime <s>porno</s> gizmodo surfing light when you’re done stuffing down all those Sufganiot.
If you’re not that much of a geek, here’s the place to note chip package pin naming convention (counter clockwise from the notch) and that the LED anode (+) is the longer lead leaving the short one to be the cathode (-).
1. You will require a battery holder for 4 AAs which will be modified to hold 3 AAs and a trimmer potentiometer A.K.A “trimpot”, anything between 10K & 1Meg will do.
The trimpot should have a control rod if you don’t want to use a screwdriver at the holiday table and the LEDs can be any color and size, but I recommend a type with long leads and a large viewing angle (i.e. not-focused since the idea isn’t to light the ceiling…)
2. First, figure out where you want 3 batteries and where you want the trimpot. Using a wire, connect between the contacts where the trimpot goes and rip out one of the battery terminals so you have a perfect hole for the rod.
3. With the trimpot I used, I drilled screwed a hole through the separation near the trimpot position and bent one of the trimpot legs to fit it.
4. Insert the trimpot leg into the hole and connect the control rod on the outside. Make sure the leg doesn’t short to the battery contact.
5. Connect the exterior trimpot legs to the (+) & (-) battery pack outputs using some wire (red & black, respectively) and a third wire (white) as a new control output wire.
That was training. Put it aside, and now for the fun part:
6. We’ll be soldering the SHORT leads of 8 LEDs to pins 10-13 & 15-18 leaving pin 14 unconnected (for symmetry)
Take an LED and bend both leads into an S shape to make the extreme left “candle” repeat for extreme right.
Bend BOTH leads into shape (unlike the picture) and bend the long (anode) lead a bit back so it won’t disturb you.
Solder the short lead to the extreme pins 10 & 18 (make sure the chip isn’t upside-down!) and bend the long lead to the other side without soldering.
Continue with the two central “candles” on pins 13 & 15. You will need to chop some of the lead to get them all in line.
7. Carry on with all LEDs making more pronounced curves as you stray away from the center towards the edges. Keep all LEDs upright at the top.
The LEDs already in place will help you position and curve the intermediate ones in an esthetic manner, solder only after the LED fits nice.
8. Make sure all is straight and fix the crooked ones. There’ll be no fixing later.
9. Chop the long, dangling leads to be just at the chip package top and bend them back to the middle of the DIP package.
10. Solder a wire across the tips and solder all tips to it. Again, start with the extremes and continue with the others.
Bend the center wire around the chip and solder it to itself on the bottom side.
11. Add the Shamash: solder the LONG lead to the horizontal wire and bend the SHORT lead just below the edge of the DIP.
Solder a second wire from pin 1 to the bent cathode (which won’t reach pin 1 without help)
12. Bend the resistor in an inconspicuous manner connecting pins 6 & 7 to one side and pin 8 to the other. An SMT resistor will be fine too but I find the regular ¼W more appropriate for the DIP.
The resistor will set the led current I(led)=12.5/R or 18mA with my 680 Ohm resistor. Don’t go over 30mA, you don’t need the brightest Hanukiah in the room.
13. Turn the chip upside-down and solder pins 3 & 9 to the central wire (+), then connect pins 2, 4 & 8 (-) together with insulated wire.
14. Take the battery pack we made, solder the red (+) to the central wire, solder the black (-) to pin 2, 4 or 8. Solder the control trimpot to pin 5.
I opted on replacing the original battery pack wires with some long, thin, 4-conductor earphone wire but the conductors are very fine and varnished and are a pain in the tachat to solder. I also glued the wire to the DIP underside with superglue.
15. That’s it! Turn the knob and they’ll light up one by one. Remember to take out the batteries or add a switch (possibly where the 4th battery is jumpered) because the batteries will drain through the IC and potentiometer even when the LEDs are all off.
HAPPY HANUKA and HAG SAMEACH!”
Yeah, what he said!