Timeline for Noise issue when powering several audio devices from the same power source
Current License: CC BY-SA 4.0
7 events
| when toggle format | what | by | license | comment | |
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| Dec 3, 2023 at 17:51 | comment | added | bobflux | Nice! Audio transformers also limit bandwidth (especially in the bass) or if they don't they're very expensive... | |
| Dec 3, 2023 at 17:46 | comment | added | Luca | Just wanted to post an update: I've rigged a horrible battery box, one for each device and the noise is completely gone, as expected. I guess this will be the way forward unless I go and use isolated DC-DC converter, because audio transformers will end up being way too expensive. I have to see how much those DC-DC converters cost and how big they are to make an educated guess on how to proceed. | |
| Dec 2, 2023 at 20:30 | comment | added | Luca | AA rechargeables, if my memory serves right, provide 1.2V, so by having 4 of them I'd get 4.8V... which might be enough if I bypass the internal 7805, but I always try to keep my gear stock and with minimal to no modification. Still, definitely an option to keep in mind. I wish balanced audio connections would be more common on audio gear. | |
| Dec 2, 2023 at 18:44 | comment | added | bobflux | You're welcome ;) So yes indeed you are hearing supply current variations from the LEDs turning on and off in the multiplexed 7 segment displays! Note if your stuff uses a regulator like 7805 to drop 9V to 5V it will require at least 7V on the input, unless you replace the 7805 with a more modern low dropout version. But AA rechargeables will only give you 1.5V per cell when fresh off the charger, it quickly drops to 1.2V per cell... | |
| Dec 2, 2023 at 18:23 | comment | added | Luca | Right on the money. Thank you so much, that makes perfect sense and it's exactly what's happening in my setup. Adding all those batteries might end up making the setup pretty bulky, but I'll definitely think about it... some of the devices might actually work with even less than 9V, so 4xAA batteries might be enough, I bet that they all have internal regulators to get the 9V input down to 5V, so I might get away with 6V input. I'll also look for isolated DC-DC converters and see how much they cost and how much circuitry they require and decide accordingly. Thanks again! | |
| Dec 2, 2023 at 18:18 | vote | accept | Luca | ||
| Dec 2, 2023 at 16:46 | history | answered | bobflux | CC BY-SA 4.0 |