anyone have a low RFI wall wart power supply to recommend?

Other Hardware General Electronics
1

I just got a powered mini usb hub to let me work on Arduino sensor projects that interface with a computer
that is 15 feet away. The minihub power supply is 5V 1000 mA.

The Arduino is connected to the usb hub and my DHT11 project works. I don't have a separate supply for the
Arduino.

The problem is a nearby radio is very noisy when the usb hub power supply is plugged in. I would like to
listen to the radio while I work and this could be a problem for my future wireless sensor projects.

I considered getting one of these RadioShack.com Official Site - America's Technology Store
for the hub power cord. But from info I saw on the web, these can't suppress the noise from poorly designed
power supplies. Investing in a quality supply makes more sense.

Does anyone know if this 5V 2A (2000mA) switching power supply - UL Listed : ID 276 : $7.95 : Adafruit Industries, Unique & fun DIY electronics and kits is low noise? Or can someone
recommend a higher quality supply?

For future reference, does anyone have a low RFI power supply for Arduino?
Is this 9 VDC 1000mA regulated switching power adapter - UL listed : ID 63 : $8.95 : Adafruit Industries, Unique & fun DIY electronics and kits low noise?

2

It is more likely to be the arduino itself rather than the power supply.
Check for one with an FCC approval, however cheaper power supplies say this without it being true.
If you can identify the actual frequency you might stand a chance.

Things to do:-
Look for a linear supply rather than a switching one.
Wrap the lead a few turns through a ferrite toroid.

3

Or use a lead like this.
I was testing yesterday and it gives a noticible improvement over a straigh cable.

image.jpg
image.jpg2592×1936 2.24 MB

4

bad_gui:
I just got a powered mini usb hub to let me work on Arduino sensor projects that interface with a computer
that is 15 feet away. The minihub power supply is 5V 1000 mA.

Does this mean you have 15 feet of USB cable?

bad_gui:
The Arduino is connected to the usb hub and my DHT11 project works. I don't have a separate supply for the
Arduino.

So what were you previously using to power the Arduino - presumably direct USB connection to the PC? Did that cause any problems with the radio, and was the radio previously as close to the Arduino/ PC?

bad_gui:
The problem is a nearby radio is very noisy when the usb hub power supply is plugged in. I would like to
listen to the radio while I work and this could be a problem for my future wireless sensor projects.

AM or FM? Substantial interference to AM radio is to be expected simply by proximity. If it is interfering with FM, now that's a concern!