# Do-It-Yourself A linear laser brush for painting with light - do it yourself

If you love photography and experimenting with special effects you will be happy to know that with a very simple circuit and a cheap laser you can easily build a sort of laser "scanner" to take impressive photos and portrait.
My project was born from a more complex automated laser scanner idea, and I decided to build this cool gadget so that you can give vent to your creativity.

## Step 1: Laser and instructions

This is a very common laser but its head projects a line, not a dot. You can easily find a red laser line on ebay.
I thought that if I was able to generate a pulse on that laser and I could set the frequency at my choice, the persistence of vision of photographic techniques should let me create many beautiful effects. Just turn flashing on and move your laser beam during the long exposure of the photo.

## Step 2: The pulse circuit

As usual I decided to use a simple and common NE555 IC. I know that this famous chip is very effective in making a square wave with personalized frequency and duty cycle.
There are formulas to determine the right resistors and capacitors values to obtain the required features, but here we just play a bit with the powerful java Falstad circuit simulator.
Here is my Test circuit (click to open it), but you also can find many examples on Falstad website.

You will notice that changing the values of components (on the falstad window right click on components and choose "edit") the frequency and duty cycle change.
With the values in the picture I obtained a 12Hz frequency and a very short pulse width (actually the wave is reversed, due to the PNP transistor). Then I replaced the 100K resistor with 100K potentiometer plus a 2K resistor; that generates a variable frequency from 12 Hz to about 60 Hz, with a center value (pot at 50K) of 20 Hz... perfect!
Furthermore, if you want to set up also the pulse duration (not only intervals between pulses) you can replace also the 10K resisitor with a 10K pot. « PreviousNext »View All Steps