Any problems with SMPS in series?

Homl · 23rd October 2010, 11:46 PM

Low voltage SMPS are so inexpensive these day. I am planning to hook two 24VDC notebook computer brick SMPS together in series to get +/- 24VDC and ground for a DIY amplifier board. Have people run into any problems or issues in doing so? How is the performance wise?
TIA

gootee · 24th October 2010, 05:28 AM

The first time you try it, you might want to test them to make sure that they are actually "isolated" types. I think you could do that by connecting a 10k resistor (say 5k or higher, if using 1/4 Watt resistors) between the 24V output of one and the 0V output of the other one, and then measuring the voltage across the resistor. If it's zero Volts, then they should be OK to connect.

RJM1 · 24th October 2010, 07:09 AM

With an ohm meter measure between the AC input ground pin and the output 0 and 24V and make sure there is no connection. If they are connected remove the AC input ground from the supply that you want to deliver the -24 V. This way your AC and DC grounds will be the same.

23rd October 2010, 11:46 PM	#1
Homl diyAudio Member Join Date: Nov 2003	Any problems with SMPS in series? Low voltage SMPS are so inexpensive these day. I am planning to hook two 24VDC notebook computer brick SMPS together in series to get +/- 24VDC and ground for a DIY amplifier board. Have people run into any problems or issues in doing so? How is the performance wise? TIA

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24th October 2010, 05:28 AM	#2
gootee diyAudio Member Join Date: Nov 2006 Location: Indiana Blog Entries: 1	The first time you try it, you might want to test them to make sure that they are actually "isolated" types. I think you could do that by connecting a 10k resistor (say 5k or higher, if using 1/4 Watt resistors) between the 24V output of one and the 0V output of the other one, and then measuring the voltage across the resistor. If it's zero Volts, then they should be OK to connect.

24th October 2010, 07:09 AM	#3
RJM1 diyAudio Member Join Date: Jan 2010 Location: Titusville, Fl.	With an ohm meter measure between the AC input ground pin and the output 0 and 24V and make sure there is no connection. If they are connected remove the AC input ground from the supply that you want to deliver the -24 V. This way your AC and DC grounds will be the same.

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