This 28 year old Stanley Vemco automatic gate uses mechanical relays. The
problem is that the relays are noisy when either the opening or closing
sensor switches are activated at the end of its travel. For example,
somebody runs over the air hose to begin the open operation. You can hear a
relay click with no problem, then the gate opens. Just before the gate is
fully open, it enables a sensor switch which interrupts power to the motor
relay. Then, you can hear one of the relays make a chattering noise which
decays in about two seconds. The same thing happens when the gate closes. It
seems to have gotten louder over the years. Since the entire circuit is AC,