Asked
— Edited
Hey guys reaching out to you to see if anyone can help me trouble shoot this problem. Alan has a set of blue tooth speakers installed. Running them Bluetooth works fine. I had to hard wire them for a video I'm shooting. I plugged in a 3.5mm plug into the jacks for incoming audio to the sound card from my computer then Audio out cable from the audio card to the audio input for the speakers. The speakers are now picking up all the electrical noise generated by the neck servos. Here is a video displaying the issue. Any ideas how to fix this issue?
Thanks in advance.
Link to video
That makes sense. The amplifier built into the speaker assembly is closest to the source of electrical noise and electrical noise, like any other "signal" simply becomes an input to the amplifier and out the speaker. Not to mention running off the same power source as the servo motors. Lots of noise can come from that path. When you turn the amplifier in the robot all the way up you amplify the noise as well as what you want to amplify. This noise is not present in the signal coming from the computer. By keeping that level lower and only increasing the computer input, you have made the signal to noise ratio better. The noise (static) is still there when the motor runs, you simply can't hear it now and the signal you want to hear overwhelms it to boot. Even if there is nothing coming from the computer at any given moment, the static noise from the motors in the robot is further suppressed by the sheer presence of the computer hookup. Sort of like the extra static you hear when a radio is not on a station.
EDIT I forgot to mention that the reason you don't hear motor static when you use the Bluetooth connection is that the Bluetooth transmission is specifically designed to eliminate interference from most sources (It uses a combination of FM transmission, Spread Spectrum, and Digital packet data exchange). When enabled, it overwhelms most noise sources. When you plugged in a cable, you shut off the Bluetooth and introduced a way for the motor noise to become overwhelming since then all you had was a regular amplifier. There are ways to ameliorate the motor noise (some have been mentioned here) but what you did is apparently good enough. Good work!
@dave, No, if i turn down the internal speaker volume then I can't hear the noise. It only happens when i turn the volume up all the way. By keeping them midway and control the rest of the sound with the volume control on the computer.
@WB, makes since on the BT. I look forward to going back to that after the video gets shot.
I'm still waiting for Alan to go on sale... is every thing still ok?
Will has been away working for the past 5 or so months on his "day job". I think he gets back home in a couple of months.