Signal level expansion apparatus as for a telecommunications sys
Speech circuit configuration
Telephone amplifier with switchable gain control
Telephone handset amplifier circuit
Telephone handset interface device
Telephone handset microphone level adjustment
Telephone handset with user-adjustable amplitude, default...
Telephone headset amplifier with battery saver, receive line noi
Telephone headset amplifier with battery saver, receive line noi
Telephone headset interface circuit
Telephone line monitor amplifier
Telephone power supply
Time dependant, variable amplitude threshold output circuit for
Time dependent, variable amplitude threshold output circuit for
Transmit by-pass cable
Universal amplified telephone handset
Universal telephone handset interface
Voice level controller