The TAR 21 telephone ring indicator relay detects AC call voltages, which it uses to control a relay in an electrically isolated circuit in order to switch on an acoustic or optical signalling device to announce the incoming call signal. Such signalling devices are usually used when the normal bell signal volume of a telephone is insufficient for area or noise reasons. The relay circuit of the TAR 21 is supplied with a mains power supply of 230 VAC, which is simultaneously used to supply the connected signalling device. The device is equipped with a sturdy aluminium housing, whose cover is fixed with two screws. The housing has two brackets for mounting in any position. The printed circuit board inside the device contains all the components and terminals. The operating range of the AC call voltage can be set on 23–54 Hz or 15–100 Hz with a switch inside the device. Call/Break bridging can be set with a further switch (when connecting optical signalling devices). Two Pg 11cable glands are provided for the 230 VAC power supply and connection of the signalling device. The telephone line is connected with a Pg 7 cable gland.
Data
sheet (PDF) User
Manual (PDF) 