Some times I take a while to understand suggestions given to me. Your idea is very good so i decided to track down a second 5VDC power supply dedicated to run the fan. I found and ordered one that is very small PCB and has mounting holes.
Thank you for your help!
I don't see a max loading capacitance rating in the datasheet.
I am going to try a very small dedicated 5VDC supply for the fan only.
Thank you
I looked at the DC to DC and there was one that claimed 5VDC in and 5VDC out but it was only rated at 200ma and the fan draws 250ma. Al the other ones required a higher input voltage than 5VDC.
I did find and order a dedicated supply that is very small and just might work.
Thanks for the idea, let me know if you have any other ideas.
I tried you idea with the help of an RC Low Pass Filter Design Tool, entered the data and it worked very nicely in that it reduced the ripple down to 100mv which greatly reduced the 310hz noise when I hooked the amp to the circuit. Now if I turn the volume up full blast I can barely hear it. The design tool returned a 1 ohm resistor value for any capacitor in the range of 680uf to 4700uf, the best quality was 2200uf but that might stress out the 5VDC SMPS?
So far this is number one on my list but have one more thing to try and that is a dedicated power supply for the fan. I ordered a PCB with mount holes that is very small 5VDC at 1 amp, I'll give it a try to see if the noise goes away completely.
Here is the final schematic of your idea that I came up with:
Thank you for your help, I'll keep you posted.
