Why do some FM transmitters have a power switch?

According to your question about the on/off switch for the Fm transmitter, A long time before, there were such kinds of FM transmitters with on/off switches. Because, that device also could select the channel (frequency), and this device type is connector by connector. Then, even if select one channel (for example, 87.7), he could hear the sound of the external device (by using an FM transmitter). However, if he wants to hear OEM radio except for the 87.7 channel, normally he could hear OEM radio channel 88.5 even if FM transmitter power is on. But, at that time, even though he selected 87.7, another channel also could not hear, so, it needs to power off about Fm transmitter. After powering off the FM transmitter, he could hear the OEM radio from the OEM speaker. That’s why needs to add a switch and needs to power on/off if the user wants to use OEM radio. Our FM transmitter products do not need to add the switch. Because our FM-16 FM transmitter is a wireless type, the user can adjust the frequency if he also could hear another radio channel during using your FM-16.

일부 FM 송신기에는 전원 스위치가있는 이유는 무엇입니까??

According to your question about the on/off switch for the Fm transmitter,
A long time before, there were such kinds of FM transmitters with on/off switches.
Because, that device also could select the channel (회수), and this device type is connector by connector.
그 다음에, even if select one channel (예를 들면, 87.7), he could hear the sound of the external device (by using an FM transmitter).
하나, if he wants to hear OEM radio except for the 87.7 채널, normally he could hear OEM radio channel 88.5 even if FM transmitter power is on.
하지만, at that time, even though he selected 87.7, another channel also could not hear, 그래서, it needs to power off about Fm transmitter.
After powering off the FM transmitter, he could hear the OEM radio from the OEM speaker.
그렇기 때문에 사용자가 OEM 라디오를 사용하려면 스위치를 추가하고 전원을 켜거나 꺼야 합니다..
당사의 FM 송신기 제품에는 스위치를 추가할 필요가 없습니다..
당사 FM-16 FM 송신기는 무선형이기 때문에, FM-16을 사용하는 동안 다른 라디오 채널도 들을 수 있다면 사용자는 주파수를 조정할 수 있습니다..