Introduction: Virtual Rotating LED Beacon (Rundumlicht)

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Here is my first very small *virtual* rotating LED beacon. And my first instructable too!

It's build from 4 x 0603 SMD LEDs. They only need a room about 2,5 mm3.

To make the round tripping light looking more realistic I wrote a program on a PIC12F629. It drives each LED with a PWM signal.

See the "virtual" rotating effect in the video...



Maybe next time I try it with 0402 LEDs ;-)

The Idea behind that project is to build a realistic looking rotating beacon for a small (1:87) police, fire or ambulance car. Normally they use only a single flashing LED.
(The examples on the following link are not build by me! RC Feuerwehrfahrzeug in 1:87 )

And now lets go to my Part... ;-)

Step 1: Make a Tiny Workbench

We need a square hole about 2.5mm. I use 4 old SMD chips and solder them on a PCB together.

First you should solder only one pin. Then bend the chip in the right position and solder one or to other pins to fix the chip.

Be sure that there is one hole of the PCB in the center of the 4 chips. We need this hole later!

Step 2: Insert LEDs

Now place the 4 SMD LEDs (Size 0603) inside the 4 chips.

Make sure that the anode from each LED is on the upper side!

Cut 3 small pieces of paper for isolation between the LEDs. (You can see them in the picture)

Paper Size:
- 1 x 2mm x 2mm
- 2 x 2mm x 1mm

Step 3: Solder the First Wire

Now here is one of the tricky parts. ;-)

Use a very thin isolated copper wire.

Remove the isolation on about 3mm.

Bend a small ring like shown in the first picture.

Put the wire in the middle of the 4 SMD LEDs and place the ring on top. (Sorry no picture before soldering.)

Solder fast and carefully all 4 LEDs and the wire ring together. (second picture)

Now you can remove the 4 LEDs out of the "tiny workbench". (third picture)

Step 4: Solder the 4 Cathodes

Now put the 4 LEDs upside down back into the "workbench".

Solder all 4 cathodes from the 4 LEDs to 4 wires.

If you finished this very tricky part you become a multi LED with 5 contacts.

1 Anode and 4 Cathodes.

Step 5: PWM or Not PWM That Is the Question!

The PWM driven version looks much more realistic than the simple on/off one...
In my case I build an 4 channel 8 Bit PWM signal generator with PIC 12F629.


If you don't have a PIC, Atmel or whatever CPU or no programmer or not the right skills you can say I don't need PWM.

Then you can build an easy 4 step counter from a 4017 CMOS decimal counter. Driven by a 555 oscillator.


Things to come: Build some sort of housing for the LEDs. I think about an 3mm LED. I have to make two of them with blue LEDs and place them on a small Police car (1:87).


Thank you for reading my basic english and have fun. ;-)
If you build your own "SMD LED rotating beacon" please show me a picture of it.

take care
WattSekunde