We still have some 555s left from the jameco box, so we decided to go with a dub siren. The dub siren is a fairly simple circuit, ideal for a beginner project. It makes a myriad of bleeps and sci fi sounds -along with the classic police siren- and, like everything dub, it taste better soaked in delay.

Step 1: List of Materials

2    555 ic
1    µa741 ic
4    4k7 resistor
2   10k resistor
1   4001 diode
1   47nf capacitor
1   0.1µf
1 220µf capacitor
3 100k pots
1   50k pot

Get the frizting file from this page to have a look. Using that as a base, we recommend first try it in a protoboard.   Put first the ics, then all the ground an 9v connections. Then all the resistors and capacitors. Have a check at the wiring needed between the ics, and last connect the pots and power. Test it out, if it bleeps and drones, you are good to go. Experiment with different values for the capacitors, the one on the leg 2 of the first 555 sets the modulation. The one in the second 555 sets the frequency (the higher value of the capacitor, the lower frequency) Just test and choose the one you hear more pleasing (or annoying) to your ears.
You can put 2 different capacitors and a switch to choose beetwen them, like you can see in the fritzing file.

dubsiren.rar
Download

Step 2:

We used a perf board with a design very similar to a protoboard, so its easy to move from the proto to the final soldered components. Check the pictures for some notes, but basically repeat the connections made in the protoboard on the final perf.

Step 3:

Once you have finished solder and checked that the dub siren its working, its time to enjoy! Just find a proper case and voilá!
In case you missed it, here there is the video again. If you build one show us yours!
Thanks to the jameco people (www.jameco.com) for sending us the components.
Dub on!