SOUND VOLUME SWITCH

PURPOSE:To smooth the switching from the transmission to the reception state, by rectifying and smoothing a part of the transmission signal and subtracting the signal from an output of a reception smoothing circuit, in a sound volume switch circuit of a loudspeaker telephone set. CONSTITUTION:A sound volume switch circuit has a bypass preventing circuit 9 preventing bypass of a transmission signal to a reception circuit, and circuits 15, 16 rectifying and smoothing the transmission and reception signals, and compares the level of smoothed signals and inserts a loss to a channel. A part of the transmission signal is rectified and smoothed and subtracted from the output of a reception smoothing circuit 15, suppresses the increase in the reception circuit rectifying output due to bypass of the transmission signal, and the margin of a transmission blocking is increased, and the loss at the transmission state of a reception auxiliary variable loss 13 can be decreased, and the switching from the transmission to the reception state can smoothly be performed.