This 2009 circuit is a bilateral call warning. Easy to build, using light communication between two rooms as one of its applications. We can give as an example its use in an office between the reception and the service room. When installed, this circuit is divided into two parts: the ENTRE circuit and the WAIT circuit, each consisting of two HH switches, a battery and four LEDs interconnected by wires. How it works:
ENTER circuit - support with connected batteries. Pressing the S1 key, LED5 (reception) and LED-3 (medical) will light up. Pressing the S4 switch, LED8 (medical) and LED-2 (reception) will light up.
WAIT circuit - support with connected batteries .. Pressing the S3 switch will turn on LED-1 (reception) and LED-7 (doctor). Pressing key S2 will turn on LED-4 (medical) and LED-6 (reception).
The ENTER / WAIT circuits each work in two ways, direct and inverse, to turn on the LEDs. The interpretation of the colors of the LEDs can be:
Green - free to ENTER
Red - busy for WAIT
