Electronics > Beginners
Replace tape block with a bluetooth receiver in a car radio
<< < (3/3)
den:
Soooo, have tested some things today and actually got it louder this time. The only problem now - very noisy. Completely disconnected tape traces and feeding directly to Audio MCU inputs. The reason it was quiet before is the same noise. When switching to tape Master MCU gave command to Audio MCU to go into Soft Mute. I thought it was something like mute (no sound), but when increasing volume it does it slowly (or the other way around). But as far as I understood from a brief search - it's actually a noise rejection feature (makes sense for tape input). Since I have tons of noise - it was reducing that and simultaneously also music volume was reduced. Using Arduino (Audio MCU talks using I2C) I just disabled that for now.
Tried to disconnect the running tape block (two el. motors) - no effect. The noise comes from a bluetooth device itself. It is not heard in a small loudspeaker, but apparently when amplified - can be heard very good. Did not take screenshots from scope yet, but one of the components is a approx. 200 kHz sine wave, which sits on top of the sound wave. This I removed pretty easily with a simple RC low-pass. But there is something else - some strange peaks in the form of triangles with 3 kHz frequency, so no filtering this time.
Any ideas why this noise is there and how to deal with it?  |O
Navigation
Message Index
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod