I have a Radio that I am modifying to be able to play a old radio programs off of a SD card.
Basically I have a mp3 player and radio in one case the mp3 play is powered off of its own power supply and the radio is powered normally but with a relay in line so that the mp3 player can cut power to the radio. Then put it own signal to the + - lines of the speaker.
Can I have both devices soldered to the + - lines of the speaker or will this cause problems?
They should never be playing at the same time. If the mp3 player is playing there should be no power going to the radio and if the radio is playing that means that the mp3 play is not playing otherwise it would have cut the power to the radio.
Is it safe to do or would I have to make some kind of mixer? Is there any way there could be some kind of feed back that could damage ether device?
The mp3 play is powered of 5v usb if that helps and the Radio is 110v. The only connection would be the - and + of the speaker with both connecting to the - and +.