I want to know how to operate a 2 way intercom..... I've made one !

Intercommunication or communication circuit Inter is a two-way communication system. It provides a reliable communication line and is extremely easy to implement. The circuit is prepared by an amplifier, two switches and two loudspeakers. We can expand this circuit by adding more speakers with the help of switches. IC LM384 functions as a power amplifier in this intercom circuit. LM384 provides nearly 2 watts of audio power through a 15-volt power supply. This intercom circuit diagram is very simple and practical circuit capable of using intercoms for homes, office intercom.



Necessary components for the two way intercom

1. Power Supply (15V)
2. Resistances (1kΩ x 2, 5.6kΩ, 22kΩ, 100Ω x 2)
3. Preset (10kΩ)
4. Capacitors (0.01μF, 0.1μF x 2, 0.047μF, 220pF)
5. Electrolytic Capacitors (10μF: 25V, 100μF: 25V x 3, 47μF: 25V x 2)
6. Transformer (disassembly 220 / 6V)
7. NE5534
8. LM384
9. Speaker / microphone (8Ω)
10. 2-way switch x 2

Cable intercommunication work

• Here the 8Ω speaker acts as a microphone, as well as speaker according to the positions of the switch.
• If switch S1 is in 'Talk' contact, L1 functions as a microphone. If it is in the 'Listen' position, L1 functions as a speaker. (Similar case applicable in L2 also.)
• The time is to consider that S1 is in the 'Talk' position and S2 in the 'Listen' position.
• Since majority speakers are available with low impedance, an impedance converter is required to retain high quality audio.
• The impedance matching is performed by the T1 transformer. (This transformer is a standard 220 / 6V transformer.)
• IC NE5534 functions as a Pre-Amplifier that increases the audio signal before applying it to the LM384 amplifier section. The gain of the LM384 operational amplifier amplifier is set to 11.
• The output volume can be adjusted by varying the R4 preset.
• To use this circuit as an intercom, the bandwidth is chosen between 160 Hz and 10 kHz. Selecting another range of bandwidth results in a HIFI amplifier.
• Set the power supply independently from the main circuit to avoid interference.
• Switching between switch positions S2 in the 'Talk' position and S1 in the 'Listen' position, L2 connects to the input section and L1 connects to the output section.
• Then L2 functions as a microphone and L1 as a speaker. This achieves 2 directional communications ...!
• Circuit easily used for intercom or home intercom systems.

Pinouts
• IC LM384
• IC NE5534