I made a circuit in which an ISD1760 chip outputs music via an LM386 IC and I like the quality and volume of sound, however, when I run an HM-TRP transmitter on the same circuit board and the transmitter is sending data out at 38kbps, I get the oscillation sound on the speaker (fast motorboat), yet I didn't ask the ISD1760 to play anything. I don't get the sound when the transmitter stops sending data. The transmitter runs on a 915Mhz frequency.
I consulted other forums and I was told its because my gain is too high, so I feel my only options are as follows:
Waste the board, build circuits so the transmitter and audio amplifier don't share the same board. (messy)
Lower the volume of the audio, but if I do that, I might not hear the sound. (not cool)
Make it where the audio and transmissions occur at different times.
Now I may be happy with #3 and I can program a microcontroller to cause #3 to occur but I have two questions on that:
- Instead of placing more demands on the micro, could I get away with a bilateral switch and a one-shot timer (like one in the CD4538 cmos IC) and connect the input of the timer to the radio transmit pin so when data is activated, the bilateral switch shuts off the speaker until a byte of data is transmitted and turn the speaker back on?
- If idea #3 is doable, will my sound significantly improve or will I still get those oscillations to a worse degree than before?