# Do-it-yourself Chanukiah (with LEDs?) **URL:** \ **Category:** Factual Questions\ **Created:** [December 19, 2005, 7:19pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330 "2005-12-19T19:19:12Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![633squadron](https://avatars.discourse-cdn.com/v4/letter/6/ee59a6/32.png) [@633squadron](https://boards.straightdope.com/u/633squadron)\ **Post date:** [December 19, 2005, 7:19pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/1 "2005-12-19T19:19:12Z")
OK, so a chanukiah is the 9-light thingie one lights at Hanukah. Despite what the goyim say, it’s _not_ a menorah; that word is used for the 6-light thing that was part of the mishkan (temple/holy of holies) and is sometimes seen in Jewish religious places today. I have always wanted to build my own electric hanukiah. Making one out of light bulbs is so dirt simple it’s ridiculous! What _I_ want is one that’s small, battery-powered, and preferably uses LEDs. It’s perfectly “legal” to make an electric one. Candles are traditional, as are oil lamps. Oil is even more fitting, given the nature of the miracle! But electricity is perfectly fine. In places with large Chasidic populations, I’ve often seen Chabad-mobiles driving around with large electric chanukiahs mounted on the roof! I kinda like that type of brash, joyful Judaism. Alas, I’m not much of an electrical engineer. I can follow plans or ideas once I see them, but I have no idea where to start. I don’t even know where to buy LEDs. Any ideas? I live in the Silicon Valley, which has ample access to electronic supplies. BTW, the exact transliteration is **chanukah**. Tons of confusion here. Wikipedia gives a ton of alternatives. Not sure why. The Hebrew is [SIZE=3]חנכה[/SIZE} which would be ch-n-k-h (hebrew having no values traditionally). :dubious: Any ideas would be most appreciated! ;j ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [December 19, 2005, 8:37pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/2 "2005-12-19T20:37:26Z")
I made a simple schematic [here.](http://img.photobucket.com/albums/v233/axpauction/schematic1.jpg) As to where to get LEDs. try [LSDiodes.](http://www.lsdiodes.com) You get free stickers! They also have a nice tutorial section n LEDs. The trickiest part is making sure you have LEDs rated for the right voltage. If you use two AA, or two D, etc… batteries, then you will have 3 volts (assuming they are wired in series.) So all you need to do is buy 9 LEDs of whatever size you want that are rated for 2-3 volts. [Here is a blue one.](http://www.lsdiodes.com/shop/index.php?main_page=product_info&cPath=2&products_id=24) [And a green one.](http://www.lsdiodes.com/shop/index.php?main_page=product_info&cPath=2&products_id=28) However, if you use, say, a 9V battery, then you’ll need resistors on each LED (or one resistor coming right off the battery before splitting into parallel gonig to the LEDs.) If you have a 9V battery, and LEDs rated for 3. 3 volts (that’s a popular rating) then you’ll need a 180 Ohm resistor (I assumed a forward current of about 30 milliamps, which is average for a 3.3 V LED.) ---
**Author:** ![zev\_steinhardt](https://avatars.discourse-cdn.com/v4/letter/z/97f17d/32.png) [@zev\_steinhardt](https://boards.straightdope.com/u/zev_steinhardt)\ **Post date:** [December 19, 2005, 8:42pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/3 "2005-12-19T20:42:53Z")
Actually, the general _halachic_ consensus is that one cannot fulfill the _mitzvah_ of lighting the _chanukkiah_ with an electric “_menorah_.” The fact that you may see _Chabad_ vehicles going around with them is not relevant, as they are doing it for “publicity’s sake” and not for the sake of fulfilling the _mitzvah_. To fulfill the _mitzvah_, you need oil (preferrably) or candles. Zev Steinhardt ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [December 19, 2005, 8:52pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/4 "2005-12-19T20:52:03Z")
> [@633squadron](#): > > It’s perfectly “legal” to make an electric one. Candles are traditional, as are oil lamps. Oil is even more fitting, given the nature of the miracle! But electricity is perfectly fine. Certainly. We have two electric menorahs in our apartment. [But an electric menorah does not fulfill the mitzvah of lighting the Hanukkah lights, so you shouldn’t say the blessings when you light it.](http://www.askmoses.com/qa_detail.html?h=486&o=33441) We don’t say blessings over our electric menorahs- they’re just decorations, we only say the blessings for the ones with candles. I have heard opinions that it’s OK to use an electric menorah instead of one with candles or oil if you have no other choice (if you’re in a hospital, for example, and not allowed to light a flame). ---
**Author:** ![cmkeller](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmkeller/32/118_2.png) [@cmkeller](https://boards.straightdope.com/u/cmkeller)\ **Post date:** [December 19, 2005, 8:54pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/5 "2005-12-19T20:54:28Z")
633squadron: > [@](#): > > it’s not a menorah; that word is used for the 6-light thing that was part of the mishkan (temple/holy of holies) and is sometimes seen in Jewish religious places today. Nitpick: the menorah in the Mishkan and Holy Temple had 7 lamps - 3 on branches on each side, and one atop the center staff. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [December 19, 2005, 9:13pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/6 "2005-12-19T21:13:10Z")
What color LEDs do you want to use? And there are 9 of them? ---
**Author:** ![Ike\_Witt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ike_witt/32/283_2.png) [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)\ **Post date:** [December 19, 2005, 9:19pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/7 "2005-12-19T21:19:32Z")
> [@zev\_steinhardt](#): > > To fulfill the _mitzvah_, you need oil (preferrably) And if you have an oil based Chanukiah, but you only have one days worth of oil and it lasts for seven days - alert your Rabbi. Zev, do you use oil? ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [December 19, 2005, 9:26pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/8 "2005-12-19T21:26:58Z")
FYI, when it comes to LEDs, it is better to try and source a constant current through them than stick a constant voltage across them. So whenever you use LEDs, you should never just stick a battery across them… you need some kind of component in series to limit or control the current. In addition, I don’t like operating LEDs in parallel; I like them in series whenever possible. So if you have 9 LEDs, you can stick them all in series and operate them from three 9V batteries in series, along with a series current limiting device (e.g. series resistor) or current controller (e.g. LM317 configured as a constant current source). A resistor would be extremely simple to implement, but you’ll have more consistent light output (as the battery depletes) if you use a current controller. ---
**Author:** ![zev\_steinhardt](https://avatars.discourse-cdn.com/v4/letter/z/97f17d/32.png) [@zev\_steinhardt](https://boards.straightdope.com/u/zev_steinhardt)\ **Post date:** [December 19, 2005, 9:27pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/9 "2005-12-19T21:27:08Z")
> [@adam yax](#): > > And if you have an oil based Chanukiah, but you only have one days worth of oil and it lasts for seven days - alert your Rabbi. > > Zev, do you use oil? Yes. If one does not have enough oil (or candles) for eight days, however, one should only light one candle per night – that is really all that is required for the mitzvah. Lighting additional lights as we do is not absolutely required. Zev Steinhardt ---
**Author:** ![633squadron](https://avatars.discourse-cdn.com/v4/letter/6/ee59a6/32.png) [@633squadron](https://boards.straightdope.com/u/633squadron)\ **Post date:** [December 19, 2005, 11:08pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/10 "2005-12-19T23:08:10Z")
> [@zev\_steinhardt](#): > > Yes. > > If one does not have enough oil (or candles) for eight days, however, one should only light one candle per night – that is really all that is required for the mitzvah. Lighting additional lights as we do is not absolutely required. > > Zev Steinhardt Zev, thanks for the clarification. I was (as usual) confused about just about everything. It is not sufficient to use an electric menorah, as you quite correctly pointed out. It’s _OK_ to do it, but it doesn’t satisfy the mitzvah. I did say that I had regular chanukiot for that, though. The custom of adding an additional light every night is Hillel’s Talmudic teaching. The “ordinary” menorah I mentioned does have 7 lights. After saying that the chanukiah has 9, I should have said the menorah has 7. Thanks to all the information about the electrical stuff. Most of it is beyond me (sob), but I’ll perservere. Joe ---
**Author:** ![633squadron](https://avatars.discourse-cdn.com/v4/letter/6/ee59a6/32.png) [@633squadron](https://boards.straightdope.com/u/633squadron)\ **Post date:** [December 19, 2005, 11:10pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/11 "2005-12-19T23:10:52Z")
> [@Crafter\_Man](#): > > FYI, when it comes to LEDs, it is better to try and source a constant current through them than stick a constant voltage across them. So whenever you use LEDs, you should never just stick a battery across them… you need some kind of component in series to limit or control the current. > > In addition, I don’t like operating LEDs in parallel; I like them in series whenever possible. So if you have 9 LEDs, you can stick them all in series and operate them from three 9V batteries in series, along with a series current limiting device (e.g. series resistor) or current controller (e.g. LM317 configured as a constant current source). A resistor would be extremely simple to implement, but you’ll have more consistent light output (as the battery depletes) if you use a current controller. I think I understand, although I’m not at all familiar with a LM317. Is a series resistor a resistor wired in series? ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [December 19, 2005, 11:38pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/12 "2005-12-19T23:38:21Z")
> [@633squadron](#): > > I think I understand, although I’m not at all familiar with a LM317. Is a series resistor a resistor wired in series? Yes. The LM317 - which is sold at Radio Shack for $2.29 - is actually a “programmable” linear voltage regulator. The term “programmable” means you set the output voltage using a couple resistors. [Here’s](http://www.fairchildsemi.com/ds/LM%2FLM317.pdf) a link to a datasheet. The neat thing about the LM317 is that you can also configure it to be a constant current source, which is ideal for something like a series array of LEDs. And it only requires _one_ programming resistor when configured as a constant current source. [Here’s](http://led.linear1.org/a-cheap-current-regulated-luxeon-star-driver-design/) a schematic of the LM317 being used as a constant current source to drive one LED. For your application, you would simply string more LEDs in series. The current can be calculated as follows: I = 1.25/R Where I is the current in amps (A) and R is the resistance of the programming resistor in Ohms. If you want (for example) 15 mA through the LEDs, then you would use a resistor of around 83 Ω. (FYI, if you want an 83 Ω resistor and are having problems finding a resistor with a value close to 83 Ω, just go to Radio Shack and buy a 470 Ω resistor and 100 Ω resistor and connect them in parallel.) Here’s what I like about using a constant current source vs. a simple series resistor: As the battery voltage decreases, the current through the LEDs will also decrease if you use a simple series resistor. If you use a constant current source, the current will remain steady (down to a certain battery voltage). You can think of a constant current source as being a variable series resistor, and the resistance is automatically lowered as the battery voltage goes down to maintain a constant current. ---
**Author:** ![633squadron](https://avatars.discourse-cdn.com/v4/letter/6/ee59a6/32.png) [@633squadron](https://boards.straightdope.com/u/633squadron)\ **Post date:** [December 19, 2005, 11:43pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/13 "2005-12-19T23:43:37Z")
> [@Crafter\_Man](#): > > FYI, when it comes to LEDs, it is better to try and source a constant current through them than stick a constant voltage across them. So whenever you use LEDs, you should never just stick a battery across them… you need some kind of component in series to limit or control the current. > > In addition, I don’t like operating LEDs in parallel; I like them in series whenever possible. So if you have 9 LEDs, you can stick them all in series and operate them from three 9V batteries in series, along with a series current limiting device (e.g. series resistor) or current controller (e.g. LM317 configured as a constant current source). A resistor would be extremely simple to implement, but you’ll have more consistent light output (as the battery depletes) if you use a current controller. Something like [this](http://i32.photobucket.com/albums/d44/jmalin/chanukiah.gif) then? I put in a resistor cuz I did it in Viso. Seems straightforward, except for that current controller. ☹ ---
**Author:** ![633squadron](https://avatars.discourse-cdn.com/v4/letter/6/ee59a6/32.png) [@633squadron](https://boards.straightdope.com/u/633squadron)\ **Post date:** [December 19, 2005, 11:55pm UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/14 "2005-12-19T23:55:58Z")
> [@zev\_steinhardt](#): > > Yes. > > If one does not have enough oil (or candles) for eight days, however, one should only light one candle per night – that is really all that is required for the mitzvah. Lighting additional lights as we do is not absolutely required. > > Zev Steinhardt I also use oil. Our local Judaica shop, \Bob & Bob, Palo Alto\ carries chanukiot that take oil as well as little glass adapters that convert a candle style to oil, and floating wicks. I’ve been advised that olive oil is preferable, and the higher quality you use, the less smoke you get. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 20, 2005, 12:02am UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/15 "2005-12-20T00:02:52Z")
> [@633squadron](#): > > Something like [this](http://i32.photobucket.com/albums/d44/jmalin/chanukiah.gif) then? I put in a resistor cuz I did it in Viso. Seems straightforward, except for that current controller. ☹ That will not work the way you want it to. With the LEDs in series, they will only light up when all 8 switches are closed (on). If you wish to able to control the LEDs individually, you’ll need to use something like **bouv** ’s schematic. In series with each LED, you’ll need a current-limiting resistor of the proper value. To determine the proper resistance, you’ll need to know the forward voltage drop across the LED (typically about 1.8-2 volts for gallium-arsenide red or green LEDs) and the driving current. The maximum forward current will be listed on the LED package, and is typically around 20 mA. Drop it down a few mA for safety, say, around 10 mA. To calculate the resistor, subtract the forward voltage drop from the supply voltage and divide the result by the driving current. For example, if you are using a 9 V batter, and you have a red LED with a forward voltage drop of 2 V to be driven at 15 mA, you’ll need a resistor of (9 - 2) / .015 or 466.6 ohms. The closest standard value would be 480 ohms, so use that. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 20, 2005, 12:04am UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/16 "2005-12-20T00:04:59Z")
> [@Q.E.D.](#): > > The closest standard value would be 480 ohms, so use that. Gah! Hit submit before I could change that. The closest [standard value](http://www.sizes.com/materls/resistorVal.htm)f would be **470** ohms, not 480. ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [December 20, 2005, 12:12am UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/17 "2005-12-20T00:12:29Z")
> [@633squadron](#): > > Our local Judaica shop, \Bob & Bob, Palo Alto\ I love Bob & Bob! I don’t go there nearly as often as I would like, though- I wish Palo Alto were closer to Walnut Creek than it is ☹ We use candles, because: hot oil + two curious cats + two Nevilles, each one a klutz with numerous burn scars from previous kitchen accidents != a good combination. ---
**Author:** ![633squadron](https://avatars.discourse-cdn.com/v4/letter/6/ee59a6/32.png) [@633squadron](https://boards.straightdope.com/u/633squadron)\ **Post date:** [December 20, 2005, 1:00am UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/18 "2005-12-20T01:00:20Z")
> [@Q.E.D.](#): > > That will not work the way you want it to. yeah, I was in a hurry. :smack: LOL. Sounds like you’re still advocating series, though. Doing the calculations isn’t that much of a problem, I hope. We shall see. ---
**Author:** ![633squadron](https://avatars.discourse-cdn.com/v4/letter/6/ee59a6/32.png) [@633squadron](https://boards.straightdope.com/u/633squadron)\ **Post date:** [December 20, 2005, 1:02am UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/19 "2005-12-20T01:02:38Z")
> [@Anne Neville](#): > > I love Bob & Bob! I don’t go there nearly as often as I would like, though- I wish Palo Alto were closer to Walnut Creek than it is ☹ > > We use candles, because: > hot oil + two curious cats + two Nevilles, each one a klutz with numerous burn scars from previous kitchen accidents != a good combination. Dig. I am lucky enough to live in Sunnyvale. B & B have a web site but no plans for doing online selling; they just don’t have the extra bandwidth. If at any time you need something, I could help out by “shopping” for you. I’m sure B & B would ship it once you had it picked out. ;j ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [December 20, 2005, 1:13am UTC](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330/20 "2005-12-20T01:13:18Z")
> [@633squadron](#): > > Sounds like you’re still advocating series, though. No, no. You need to have them in parallel if you wish to be able to control each LED individually–see **bouv** ’s schematic. If you want them either all on or all off, then you can use a series arrangement, which is more efficient. [Next page](https://boards.straightdope.com/t/do-it-yourself-chanukiah-with-leds/336330.md?page=2)