Abstract: A method for actuating an access control transmitter in which a four code access transmitter is employed with the dimmer switch flashed once to produce a first signal, twice in rapid succession to produce a second signal, three times in rapid succession to produce a third signal, and four times in rapid succession to produce a fourth succession. Each separate signal is an access controlled signal to gain access to an access controlled area such as a garage. Programming of the access controlled transmitter occurs by actuating a standard transmitter nearby, when the access transmitter is in a programming mode. A programming access mechanism is provided to prevent authorized programming of the access transmitter by one not having the programming access code.

Abstract: An AC power line is monitored for currents and voltages at non-fundamental frequencies (including harmonics). A controlled active filter injects compensating current into the AC power line. The injected compensating current is responsive to both the sensed non-fundamental frequency current and to the sensed non-fundamental frequency voltage residing on the power line. In one embodiment, the controlled active filter comprises a transconductance amplifier which obtains its operating power from a controlled flow of power from the AC power line being monitored.