# PCB Heaven

## General Category => General Discussion => Topic started by: Kunkel on September 10, 2014, 02:09:04 AM

Title: Newbie help with power supply noise
Post by: Kunkel on September 10, 2014, 02:09:04 AM
Hi,

I have been learning practical electronics with the help of your site and Talking Electronics, besides a few books like "The Art pf Electronics" and "Teach Yourself Electricity and Electronics". I have also repeated the word "electronics" 5 times since I got here :)

I studied Environmental Engineering, so I have enough math background besides some physics, namely electromagnetism and optics. However, I'm just starting to build circuits and do some repairs, only low voltage stuff so far.

Building guitar effect pedals has been a good introduction but now I find myself with a problem that I'm sure will be easy for you guys: I have this "universal power supply" working at 9v, 600mA max

http://www.clickplus.pt/p1191

However I find it adds too much noise when powering the pedals (comparing to a 9v battery, for example). It was cheap, so I think it might be limited but I would like to save some money and learn while trying to fix this, if possible.

My question is if I can build some circuit to work as a filter between the power supply and guitar pedals (or maybe power my breadboard projects). As far as I understand, maybe a couple of capacitors and diodes would help "clean the wave" but I'm not sure.

Thank you in advance.
Title: Re: Newbie help with power supply noise
Post by: kam on September 10, 2014, 15:00:54 PM
Hello Kunkel,

first of, make sure that this is not a piece of junk like this one (click) (http://www.pcbheaven.com/userpages/how_cheap_is_a_power_supply). Use an oscilloscope to see the output.

You can use a set of 2 or 3 different electrolytic capacitors in parallel to smooth the output. Say, 1uF, then 100uF and maybe a 2200uF or higher. Also connect a 0.1uF ceramic for the high frequency switching.
If the problem still exists you need to go with high frequency filters

Title: Re: Newbie help with power supply noise
Post by: Kunkel on September 10, 2014, 22:11:23 PM
Hum, I actually only have 1000uF instead of 2200uF, I'll have to get a replacement.

I dont have a oscilloscope yet, I was thinking of getting one of these things: