infrared-radio

Description: The circuit illustrated here represents one half of a device that is highly useful for tracing electrical wiring paths within a building or identifying breaks in wires. This system is based on equipment commonly used by technicians in telephone exchanges. The operation is simple; a generator is required to produce a recognizable signal, which is inductively coupled to a high-gain receiver using a short antenna. To create an effective transmitter, a basic generator can be constructed using a 555 timer, but a 556 timer has been selected instead in the adjacent diagram. The second timer (IC1a) modulates the tone generated by IC1b, resulting in an output frequency that alternates between approximately 2100 Hz and 2200 Hz. This distinctive test signal is easily identifiable among other signals that may be present. Resistor R6 is connected to a wire approximately ten centimeters long, which serves as the antenna. The ground connection, located at the junction of C2 and C3, is connected to the ground. When the antenna is directly connected to a cable, it enables the determination of which conductor is which at the opposite end of the cable, although this should not be done with live conductors. The schematic for the corresponding receiver can be found elsewhere on this website.

The described circuit operates as a signal transmitter designed for wire tracing applications. The use of a 556 timer integrated circuit allows for dual functionality, where one timer modulates the output signal frequency while the other timer generates the base frequency. The modulation between 2100 Hz and 2200 Hz is specifically chosen to ensure that the signal stands out against typical background noise, making it suitable for effective tracing.

The antenna, formed by a short wire connected to resistor R6, plays a crucial role in transmitting the generated signal through inductive coupling. This method allows the signal to propagate along the wiring system without direct electrical contact, which is essential for safety and efficiency in identifying breaks or tracing wires. The ground connection provides a reference point for signal stability and enhances the overall performance of the transmitter.

When employing this circuit in practical applications, it is essential to ensure that the antenna is connected only to non-live conductors to avoid hazards. The complementary receiver, which is referenced but not detailed in this description, is designed to pick up the transmitted signal, allowing users to discern the specific conductors in a wiring setup. This capability is invaluable for electricians and technicians when diagnosing wiring issues or performing installations.The circuit depicted here forms one half of a device that will prove extremely handy when tracing the path of electrical wiring in a building or to locate a break in a wire. The system is based on similar equipment that is used by technicians in telephone exchanges. The operation is straightforward. You require a generator that delivers an easily recognizable signal which, using a short antenna, is inductively coupled to a simple, but high gain, receiver. To create a useful transmitter it would suffice to build a simple generator based on a 555. But as the adjacent diagram shows, a 556 was selected instead. The second timer (IC1a) is used to modulate the tone produced by IC1b. The output frequency alternates between about 2100 Hz and 2200 Hz. This is a very distinctive test signal that is easily distinguished from any other signals that may be present.

Resistor R6 is connected to a piece of wire, about ten centimeters long, that functions as the antenna. The ground connection (junction C2-C3) is connected to ground. When the antenna is connected directly to a cable, it is possible to determine at the other end of the cable, with the aid of the receiver, which conductor is which (don`t do this with live conductors!).

The schematic for the matching receiver may be found elsewhere in this website.