I can't say I've ever owned a circular saw with an electric brake.
I can think of two possibilities:
1. A physical brake pad arrangement held on by springs with a solenoid to pull the brakes off when the trigger is operated.
2. Switch contacts which re-arrange the motor connections when the trigger is released to short the armature to achieve braking (similar to the rheostat braking used on electrio trains).
I can't think why an add-on accessory would have a problem with brakes though.
[This message has been edited by pauluk (edited 03-12-2005).]
