My motorcycle's licence-plate (type 1156) illumination bulb recently failed and rather than buy another incandescent bulb, I decided to hack/repair/convert it to LED.  This LED hack should last much longer that the incandescent bulb that it replaced.

Caveats: This hack worked great for my license plate illumination, but it will not work for brake light application since these are usually dual filament bulbs and it will not work for turn signal bulbs unless you also change your flasher to one that is compatible with LEDs.  There are many sites that sell LED retrofit bulbs and flashers for older vehicles for some examples, search Ebay for "LED 1156" or  "LED 1157" or "LED 3056" or "LED 3057" or "LED flasher".

Parts required:  4 white LEDs

Note: For my build, I used LEDs salvaged from another project, and most white LEDs should work or this license plate illumination hack, but before you purchase your LEDs you should check the brightness rating on the data sheet and verify that it is adequate for your application e.g. Digikey part # 160-1850-ND has a brightness rating of 17000mcd.

Tools required:  gloves, safety glasses, pliers, wire cutters, soldering iron, hot-glue gun, multimeter, power supply (for testing)

Step 1: Deconstruct the Bulb

Do this step inside a trash bin so glass will be contained and wear gloves and wear safety glasses for protection.  Use a pair of pliers to remove the glass bulb.  You will also need to remove the inner glass structure to expose the 2 internal wires.  Use wire cutters to trim the 2 wires to a length that extend about 1/8" out of the base (see picture).  Use a multimeter to determine which of the 2 wires is ground and make a note of this for the next step (wiring the 4 diodes in series).

Step 2: Wire Four White LEDs in Series

Wire the four LEDs in series as shown in the circuit.  The LED anode(+) and cathode(-) can be recognized by the flat side of the plastic lens or by the lead length as shown in the diagram.  My application was for licence plate illumination so I wired the LEDs in a straight line and oriented them in the direction that I needed the light.  Unlike incandescent bulbs, LEDs are a directional light source so arrange your LEDs appropriate for your application.

Once you have everything soldered, apply +14V to the bulb.  The preferred method to test this is with a current-limited bench power supply.  If it doesn't light up, check your connections and polarity.

Step 3: Encapsulate the LEDs With Hot Glue

Apply hot glue to fix everything in place.  You could also use epoxy, but hot glue is faster and should be adequate for this application.  Make sure you have the LED orientation correct before you glue it and also make sure no wires touch that could cause a short.

After the glue has cured, it's ready for the final test.  Plug the new converted LED into the socket and verify that it works.

i keep asking for a 12vdc sequential led turn signal circuit . other than a 555 timer is there an alternative and i am a nice guy leaving a nice comment.
Hi, Depending on how many LEDs you want to control .. You could use an embedded microprocessor circuit to control LED sequencing, but that might be overkill. Here is an example: <br><br>https://www.instructables.com/id/LED-Strip-Controller-w-LED-Amp-Arduino/<br><br>Regards,<br>
<p>well thank you my friend! different ones think i'm crazy whenever i break bulbs to do this same conversion. they cannot fathom + and - and i always get a crass remark but i've been converting to leds' for over 25 years. led conversion of the brake/tail light is complicated by the fact that motorcycle regulators utilize the power grabbing bulb to vent some volts. i use 7 volt inline regulators from honda to trim voltage after total led conversions at coil/s as they overheat and you walk until this is contained.should you ever do this conversion just check your voltage output at battery with different rpms. 3-4500 will be true output average rpm and voltage trimmed to 14.4</p>
Hi and thanks for the comment. My current bike (a 2001 Kawasaki Concours) has an automotive-type alternator and voltage regulator and the voltage seems well regulated across RPMs. But I recall a previous bike (a Suzuki GS850) that used a shunt regulator and the headlight/taillight were definitely a required load for that bike. If the headlight burned out, the shunt regulator was not far behind ;)<br>Regards,

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