TP~3

Sound powered telephone TP-3 is voice powered, requiring no dry cells for operation. A Neon Lamp and a key switch are included in this telephone for alternate reciept of a visual signal when the sound of the ringer would be otherwise objectionable. Telephone TP-3 is identical to Telephone EE-8 with respect to case, chassis, generator and ringer. However, EE-8 has a holding coil and capacitors not required in TP-3. Sound Powered Handset TS-10( ), is included in TP-3 as compared with battery operated Handset TS-9( ) included in EE-8

Telephone TP-3 provides two-way signalling and voice communication over approximately six miles of Wire W-110-B (dry) or three and one-half miles of Wire W-110-B (wet).

Handset TS-10-( ) has magnetic balanced armature type transmitter and receiver units. The power output of the transmitter is approximately 30 db below that of a battery operated transmitter; however, the sensitivity of the receiver unit is approximately 10 db better than that of the receiver unit part of the battery operated handset.