These are the parts I used for my system with links to purchase at the time of this posting. I am not in any way affiliated with these sites and am not responsible for their content or products. Be sure to use parts that are appropriate for your application.
I built my own current sensor by modifying a 12.6V 300mA PCB-Mount Miniature Transformer
This is very easy to do and if anyone wants to go that way, you can find instructions in The Best of Fine Woodworking - The Small Wood Shop I can not repost the information or pictures from that book due to copyright but you can read it online here.
Side Note: Quick Background
I actually built the circuit in that book. It is a very old design, electronically speaking, and it was very challenging to find the parts. Some of them I had to get on eBay from overseas! It was a lot of fun and I’m glad I built it but it did not work very well. The relay clicked 3 times rapidly before staying on and I did not think that was good for my brand new dust collector. Also, it did not have a remote control function.
Instructions For Use
Caution: Do not use both switches in the On position simultaneously. If both switches are on and the Manual On/Off switch is switched off, the X10 module will latch in the on position. Turn off both switches to reset the X10 module.
1. The Automatic Dust Collector Swich (ADCS) Power Switch controls power to the appliance module. Turning this on arms the system for Auto and Remote Modes. Turn off the Manual On/Off switch before arming the system.
2. The Manual On/Off switch manually triggers the contactor on/off and turns on/off the dust collector. Turn off the ADCS power switch before using manual mode.
Always leave the ADCS Power Switch and the Manual On/Off switches off when not in the shop. As an added precaution you can turn your dust collector switch to the off position when not in use.
That’s all for now.
-- How valuable is time to a person who spends his disparaging the beliefs of others? --David Berthelette www.pilotwoodworks.com