REFLECTOR: i pad / radio noise

[John Dibble]

On 9/8/2013 12:04 PM, Brian Michalk wrote:
> I had a power adapter screw with my car.  I bought another one, and 
> the problem went away.
>
> When I build my circuit boards, the biggest noise problem I have is 
> when a voltage regulator oscillates.  It either needs more 
> capacitance, or a lower resistance (ESR) capacitor to prevent the 
> oscillation.
>
> I suggest getting a new power adapter.

Would a more expensive adapter work better?  Or a certain brand?

Thanks,

John
>   If that is not an option, take it apart and add some ceramic caps to 
> any caps that already exist.  Kind of difficult if you don't have an 
> oscilloscope.
>
> No, shielding the cord most likely won't help.  I'll bet it's noise 
> injected into the power lines in the form of voltage spikes.  It's not 
> a radiation problem like magnetic or RF.
>
> On 09/08/2013 08:13 AM, John Dibble wrote:
>> I now understand why there is concern with the use of personal 
>> electronics on commercial aircraft. Previously I reported erratic 
>> radio noise.  It was the same noise as I get when I pull the volume 
>> knob to receive weak signals.  Also my nav was not picking up VORs 
>> very well.  After a long discussion with an avionics technician I 
>> decided to investigate my i pad.  He said that because it's not 
>> shielded, it can interfere.  I had a hard time believing that because 
>> many are using the i pad and no one else is complaining. However, I'm 
>> using a power adapter and he said that can be a problem also. So I 
>> tried unplugging the power adapter and, sure enough, the radio noise 
>> went away.  Also the nav came alive and picked up VORs like it 
>> should.  I also found that if I turned off the alternator, I could 
>> leave the power adapter plugged in and the radio noise was gone.  
>> This did not eliminate the nav problem, however.  So now I'm turning 
>> to the electronics wizards in the group to see if there is any way I 
>> can have my power adapter and use it too.  Would insulation around 
>> the power cord help?
>>
>> Thanks,
>>
>> John
>> _______________________________________________
>> To change your email address, visit 
>> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery!  www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
> _______________________________________________
> To change your email address, visit 
> http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery!  www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>