How to suppress spikes on power supply

kmt · 14th February 2004, 12:34 PM

Hello to everyone!

I've a question concerning spikes on power supply: I've built up a headphone amp using a NE5532A and two BUF634. It works pretty good, very low noise etc. The only problem is the power supply. The PCB is powered by +/- 15V. For the power supply I used a toroidal transformer (30VA, +/- 15V) connected to a rectifier B40C3300. The +/- Va outputs of the rectifier are connected to 2 capacitors 1000µF.

I use 7815/7915 regulators to generate the voltages for the headphone amp. Inputs and outputs of these Vregs are connected to GND via a 100nF capacitor. Output is stabilized by a 220µF cap. The ripple voltage of the supply is very low, but I have switching spikes at the V+/V- when I turn on/off other electrical equipment (e.g. soldering station etc.)

My question is: what's the best/easiest way to suppress switching spikes on the power lines?

Any hints would be helpful

Greetz

Kai

Pjotr · 14th February 2004, 12:50 PM

Hi Kai,

For a headphone amp best is to use NOT a toroidal transformer but one that has inherently better PSU noise suppression. Use trannies with a U-shaped core and complete separated windings. These are available in Germany from Hahn transformers and Block. But Hahn is better quality IMHO.

You can start with a 250V VDR noise suppressor (“Transzorbs” and the like) across the mains if there is a lot of mains pollution. Use a big enough one of at least 25 mm diam. Ready-made spike and noise suppressors are available from a computer store.

Cheers

14th February 2004, 12:34 PM	#1
kmt diyAudio Member Join Date: Dec 2003 Location: Hamburg	How to suppress spikes on power supply Hello to everyone! I've a question concerning spikes on power supply: I've built up a headphone amp using a NE5532A and two BUF634. It works pretty good, very low noise etc. The only problem is the power supply. The PCB is powered by +/- 15V. For the power supply I used a toroidal transformer (30VA, +/- 15V) connected to a rectifier B40C3300. The +/- Va outputs of the rectifier are connected to 2 capacitors 1000µF. I use 7815/7915 regulators to generate the voltages for the headphone amp. Inputs and outputs of these Vregs are connected to GND via a 100nF capacitor. Output is stabilized by a 220µF cap. The ripple voltage of the supply is very low, but I have switching spikes at the V+/V- when I turn on/off other electrical equipment (e.g. soldering station etc.) My question is: what's the best/easiest way to suppress switching spikes on the power lines? Any hints would be helpful Greetz Kai

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14th February 2004, 12:50 PM	#2
Pjotr diyAudio Member Join Date: Nov 2002 Location: Netherlands	Hi Kai, For a headphone amp best is to use NOT a toroidal transformer but one that has inherently better PSU noise suppression. Use trannies with a U-shaped core and complete separated windings. These are available in Germany from Hahn transformers and Block. But Hahn is better quality IMHO. You can start with a 250V VDR noise suppressor (“Transzorbs” and the like) across the mains if there is a lot of mains pollution. Use a big enough one of at least 25 mm diam. Ready-made spike and noise suppressors are available from a computer store. Cheers