| 摘要 |
PROBLEM TO BE SOLVED: To provide an oscillation preventing circuit without causing any oscillation phenomenon in a one-way speech loudspeaker and a two-way communication purpose transmitter-receiver, and capable of conducting call transmission and reception at the same time especially in the two-way communication purpose transmitter-receiver to attain stable two-way speech. SOLUTION: A charging switch circuit 11 and a transfer switch circuit 12 are connected in series between amplifier circuits 8 and 9, an instantaneous signal storage member 13 is provided between the charging switch circuit 11 and the transfer switch circuit 12, the charging switch circuit 11 gives a signal from the amplifier circuit 8 to the instantaneous signal storage member 13, the transfer switch circuit 12 gives the signal from the instantaneous signal storage member 13 to the amplifier circuit 9, and the oscillation preventing circuit is characterized in that it is provided with a control circuit 15 that controls both the switch circuits so as not to be simultaneously switched on at all times by turning off the transfer switch circuit 12 when the charging switch circuit 11 is turned on and turning off the charging switch circuit 11 when the transfer switch circuit 12 is turned on.
|
