I just installed an iVac pro switch system on my Stinger to control the DC. It's RF remote attaches to the outside of the power cord of the spindle. When it senses current flow it sends a signal to the switch to turn the DC on. When the power to the spindle stops the remote sends a signal to power off the DC. The 2hp DC pulls about 20 amps so I had to put a contactor relay switch inline to handle the current draw. The system is completely non-invasive and requires no integral hookup to the machine. So far, it seems to work really good.