View Full Version : i-Socket Autoswitch modification for the Carvewright

03-26-2014, 07:31 PM
Although the i-Socket Autoswitch http://dgcproducts.com/ can be used with the Carvewright as is, one somewhat annoying behavior is that a connected dust collector will turn on for several seconds each time the cut motor spins up momentarily during setup. I didn't think too much of it, but another forum member recently pointed out that this causes unnecessary wear on the dust collection motor, start-ups being hard on the motor.

I came up with a simple modification to the i-Socket to eliminate this. The i-Socket uses a current transformer to produce a small AC output when current is drawn by the controlling tool. This output is rectified and run through a simple RC low-pass filter (1K ohms and 10uF) before feeding a microcontroller port. I increased the RC time constant by replacing the 1K resistor with 100K and adding a 47uF capacitor in parallel with the original. This is sufficient to delay switched tool start-up by a second or two, long enough so that the brief cut motor spin-ups at setup do not trigger. (This modification also increases turn-off time by a second or two, but this only adds a bit to the factory 7-second delay.)

To make the modification, R4, a 1K surface-mount resistor, must be removed. This can be a little tricky without a proper removal tool. I did not have a surface-mount 100K resistor, so I kludged in a 1/8 watt through-hole resistor. The extra 47uF capacitor can be added using some test points on the circuit board. The negative lead of the capacitor connects to TP9 and the positive to TP1.

My installation is a little different, because while I was at it I added another means to activate the switched tool socket, an optically-isolated low-voltage turn-on input. I use this with a wireless remote setup to turn my DC on for shop tools other than the Carvewright. (This remote also automatically closes a blast gate to the Carvewright: http://forum.carvewright.com/showthread.php?18330-Automatic-blast-gate&p=154666#post154666.) In my case, the added capacitor and other parts were put onto a small perf board and tucked into a cavity in the i-Socket case. If only the Carvewright mod is made, the red, yellow, and black wires and the perf board are not needed - the added capacitor can sit right on the i-Socket circuit board.

The i-Socket that I modified was recently purchased and has a different circuit board and components than an earlier one. The newer one uses a relay in place of a triac to switch the controlled tool, and the circuit board layout is different. I did not verify that the filter resistor R4 and test points are the same in the older version. Your i-Socket may not match my photo and description. Of course any modifications you may make are at your own risk; posting for information only, I assume no responsibility.


03-26-2014, 07:38 PM
Nice work. I have a different brand and it sometimes turns on with the servos. I have been wanting to take it apart and see if I could not change the current triggering threshold.