Abstract: A quick change adaptor for a hole saw includes an arbor, a collar and a retaining nut. The adaptor allows a hole saw to be easily and efficiently mounted and dismounted to and from the adaptor. When mounted to the adaptor, the hole saw and collar rotate relative to the arbor and the retaining nut. Rotation of the collar and hole saw relative to the retaining nut is limited by the interaction between an arbor boss and a collar recess to provide a drive force to the hole saw.

Abstract: A retaining collar assembly for use with a hole saw arbor assembly. The arbor assembly includes a shaft, a hole saw attached to the shaft, a drive collar retained on the shaft for engaging the hole saw and a spring retained on the shaft. The retaining collar assembly includes a retaining collar which is retained on the shaft and abuts the spring such that the spring urges the retaining collar towards the drive collar. An axial limiting area is disposed on the shaft spaced away from the collar with a retaining collar rotating area disposed therebetween. The retaining collar rotating area allows the collar to rotate about the shaft while the axial limiting area only allows axial movement and not rotary movement. Protrusions and recesses are formed on the retaining collar and drive collar to prevent rotary movement of the retaining collar and drive collar relative to one another when the retaining collar is positioned in a retaining position.

Abstract: A coupling network for transferring electronic signals from the output of a first stage to the input of a second stage. The coupling network includes a resistor, a capacitor, and an electronic circuit for connecting the resistor and the capacitor in series between the output of the first stage and the input of the second stage with the resistor positioned between the output of the first stage and the capacitor.