The Alcotron is very user-friendly, operated via two simple mechanical switches. If the operator pushes one switch, the machine produces one type of cocktail (a vodka screwdriver). When the operator pushes the other switch, the machine mixes another drink (a rum and coke).
As soon as the switch is pressed, a rotary encoder senses the position of the rotating turntable (and thus the cocktail glass that sits on the turntable) relative to the stationary base. The encoder actuates the motor until the glass is under the desired first bottle. When the glass is in place, the motor stops and the computer code actuates the valve by powering it with a relay. The process happens again with the second desired bottle. When the drink is ready, the motor turns the turntable until the encoder senses that the glass is in the original starting position.
Bottom's up!