How to inject noise on a DC power supply?

Thread Starter

Mozago

Joined Jun 14, 2017
10
Hello,

Please let me know if this is the wrong place to post this.

I have a power supply design I need to test the filters on. In order to do this I need to inject noise into its 30 VDC input.

The noise will need to look something like CH1 here:

Capture.jpg

That's approximately 6V pk-pk of noise.

I expect I'll need a signal generator of some kind but I'm not sure how I would go about doing this. Any help would be greatly appreciated.

Thanks
 
Last edited:

crutschow

Joined Mar 14, 2008
25,645
Then to inject the noise you can use a large inductor in series with the 30V supply to keep the noise signal from being filtered by the source.
 

MrChips

Joined Oct 2, 2009
22,089
That is not going to be easy. By definition, an ideal voltage source would have zero impedance. How are you going to overcome the low impedance of the power supply? You will have to isolate the power source from its output filter circuit and since the filter circuit is integral to the power supply that will be very difficult to do.

Edit: What you need is a load on the power supply that draws random current at various frequencies.
 

Thread Starter

Mozago

Joined Jun 14, 2017
10
Thanks for all the input but I couldn't figure out a way to make anything work in my application. This looks like it might be the closest I can get:

Capture.PNG

It's a 6V pk-pk sine wave offset by 30V by putting the signal in series with the DC source. I might be getting my hands on a function generator soon. Any thoughts on using a function generator and a DC supply in series like this?

Thanks
 

Bordodynov

Joined May 20, 2015
2,697
You can use a pulse transformer in series with the power supply. Next, you need a noise amplifier with the necessary low output impedance. From the amplifier output through the capacitor, the voltage is applied to the primary winding. The outer diameter of the ferrite toroid is 50 millimeters.
See
2018-10-05_15-41-54.png
 

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Last edited:

danadak

Joined Mar 10, 2018
4,057
You can use a V > I converter as a load and just pipe the
noise into the input. This results in a noise current injected
into output. You use it in addition to normal load.



Regards, Dana.
 
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