초록 ▼

A telephone test instrument permits voice communications with and monitoring of a telephone circuit to be tested. The instrument includes a microprocessor used in controlling various functions of the instrument. The microprocessor and other circuits of the instrument are energized from a connected t

A telephone test instrument permits voice communications with and monitoring of a telephone circuit to be tested. The instrument includes a microprocessor used in controlling various functions of the instrument. The microprocessor and other circuits of the instrument are energized from a connected telephone circuit and/or an internal energy supply which is automatically recharged from the telephone circuit. The microprocessor continually checks the voltage of the internal energy supply and automatically turns off a loudspeaker of the instrument, or prevents it from being turned on, if the voltage is too low. The instrument includes circuitry which, in combination with the microprocessor, measures loop current or line voltage while the instrument is connected for making voice communications with the telephone circuit. When the loudspeaker within the instrument is energized, the earpiece receiver remains active. A belt hook connected to a housing of the instrument can connect an electrical ground through a switch in the instrument to the telephone circuit for providing a ground start. The instrument also includes a “crow-bar”circuit which effectively open-circuits the instrument from a connected telephone circuit if too high of a loop current flows.

대표청구항 ▼

A telephone test instrument, comprising: means for connecting said test instrument to a telephone circuit; an internal energy supply; means, connected to said means for connecting, for energizing said instrument from the telephone circuit with a current up to a predetermined current load; and means,

A telephone test instrument, comprising: means for connecting said test instrument to a telephone circuit; an internal energy supply; means, connected to said means for connecting, for energizing said instrument from the telephone circuit with a current up to a predetermined current load; and means, connected to said energy supply, for connecting said energy supply to energize said instrument with additional current in response to said instrument requiring current above the predetermined current load.