I discovered a pretty cheap way to use as many loud sirens as you want triggered by x-10 motions without a control panel or siren drivers etc.
I just use an appliance module (AM466) with a 24VAC Transformer plugged into it. Then run several Gentex 12/24VDC Multi-tone Mini Horns directly off the transformer.
With the appliance module you need codes transmitted to it on the power lines so I use an All Housecode RF Transceiver & PowerLinc II (WGL 30015) which has good reception up to 150' without many obstacles to receive the motion detector's RF signals. You can use a key chain remote (keyfob) to turn it off, and unplug the transformer or appliance module when the area or building is in use.
The Gentex GX91/GX93 is listed for use with both filtered and unfiltered power and is a commercial fire alarm siren. They are really cheap too. It is also the only siren I've found to work directly off 12 or 24 Volts without a control panel or siren drivers and the AC to DC difference doesn't affect it either.
