The reviewed phone repeater circuit can expand the range of your land line ring sound from the phone such that a person has the ability to make a call heard in another room or maybe in another house.
THe circuit is generally linked with an hooked up buzzer, the buzzer with a driving circuit is then further employed to expand the range of it. Possibly even a caution light (a light bulb / bulb as an illustration) when be hooked up just in case a person with hearing impairment was to apply in the device. To gain numerous units you are able to attach much more than relay output contacts for the particular loads.
How the phone repeater operates:
The signal is extracted immediately from the telephone lines. The current from the lines sends through a set of capacitor C1 and resistors R1, R2, R3 and a rectifier bridge produced by diodes D1, D2, D3, D4. As a result a filtered DC signal is attained which can be then placed on the base of transistor Q1 through a positive pulse signal.
The transistor Q1 reacts to the rhythmic pattern of the signal obtained at its base, which results in an inverted and amplified signal across its collector resistor. This amplified collector signal is restricted by the set of resistor R5 and capacitor C2 network ensuring that the signal is not pulsed rather direct and straight. This modified DC is then employed on the set of Q2 and Q3 transistors associated in Darlington configuration for further amplification to ensure that the final output is prepared to actuate the relay to turn on the buzzer. D5 is utilized to preserve transistors Q2 and Q3 for reverse relay coil back EMFs.
Telephone Ring Amplifier/Repeater extension Circuit
List of components for the suggested Telephone repeater circuit
– 2 transistors Q1, Q2: BC547B
– One transistor: Q3: BC337
– Five diodes D1, D2, D3, D4, D5 1N4148
– One capacitor C1: 0.033uF
– 1 electrolytic capacitor: C2: 1uF, 50V
– Two resistors R1, R2: 100K
– 1 resistor R3: 8.2K
– 1 resistor: R4: 180K
– 1 resistor: R5: 39K
– 1 relay (relay) 12V
– 1 12V loud buzzer
Caution: Do not reverse the polarity of the telephone wires to the repeater.