Timeline for Need help extracting line out signal from car radio
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
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| Oct 10, 2018 at 20:27 | comment | added | Phil G | That should be OK then. Assuming that the input is resistive, that'd give a cutoff frequency of 6Hz. | |
| Oct 10, 2018 at 20:10 | vote | accept | myexec | ||
| Oct 10, 2018 at 20:10 | comment | added | myexec | Well from the amp documentation the pre-in impedance is 15 kΩ. | |
| Oct 10, 2018 at 20:04 | comment | added | Phil G | That'd work. Depending on the input impedance of the amp you might get away with a smaller cap to reduce the settling time. | |
| Oct 10, 2018 at 19:37 | comment | added | myexec | Would a 4.7uF capacitor with 10Kohm resistor do the job? | |
| Oct 10, 2018 at 19:25 | comment | added | Phil G | Exactly that. C223 and C224 decouple the outputs from IC23 going into IC31 and IC32 for the front signals, but all of these are using the same 4V reference (though buffered through the other opamp in IC35), so there likely wouldn't be much difference across those two caps, just the amp offset errors. The inputs to IC31-34 are biased separately via R301, R302 so that the caps will assume an appropriate DC differential. All these caps having to settle is likely to cause a good thump on power-up, hopefully your external amp has an anti-thump circuit that blanks the input at power-up. | |
| Oct 10, 2018 at 19:01 | comment | added | myexec | So if I understand you right this answer is the solution: electronics.stackexchange.com/a/178938/200858. But I see there is already a capacitor right after the outputs from the microcontroller and still there is 4v DC after that. | |
| Oct 10, 2018 at 18:45 | history | answered | Phil G | CC BY-SA 4.0 |