This is my drawdio implementation, mounted in an air action vigorsol box.
I've used a NE555, this chip has enough power to move a small 8ohm speaker, so you can omit - as i've done - the pnp transistor and 10ohm resistor of the schematic, and connect the speaker directly to the pin 3 of the 555 timer. But if you need more power, or if you use the low voltage version of NE555 you should add a Class B 'pushpull' amplifier, or even one simple transistor as you can see in my circuit.
Also i've connected two screws as drawdio contacts.
- read risk disclaimer
- excuse my bad english