Power switch location..

boxerboxer · 15th June 2009, 02:40 AM

I'm working on a build of Steve Bench's RIAA5 using salas's shunt reg. I'm planning on putting the power supply in a separate enclosure which will be out of sight (and maybe difficult to reach. It would be nice to have the on/off switch on the main unit. Is there a safe way to do that? Lifting the ground for the power supply would shut off the preamp but the power supply wouldn't really be off, would it? Or what about a relay in the power supply to disconnect the PT primary? As long as it could handle the current and defaulted to open rather than closed that should be ok, right? Means an extra conductor in the cable from PSU box to pre box but that's not a big thing.

boywonder · 16th June 2009, 03:44 AM

A relay in the PS module is convenient, also allowing low voltage up to the switch if desired, but you need some "always on" voltage in the PS (for the relay coil) so that when you flip the switch the relay is energized and closes the mains for power-up.

DigitalJunkie · 16th June 2009, 03:59 AM

A small 'wall-wart' might suffice for a small stand-by supply for the relay. (Even that would be overkill,for just a relay.)
Maybe you could find a small PCB mount power trans.

Rob11966 · 16th June 2009, 04:38 AM

Hi Boxerboxer,

I have done this with all of my amps. I use a small 9v PCB power transformer and rectify the 9v supply with a simple bridge rectifier and capacitor arrangement. This provides the 12v (or thereabouts) for the relay coil and any LED's/lamps you need to power.

As far as the relay goes, I use a 3A solid state optical relay to power the power transformers (like this one -http://www.jaycar.com.au/productView.asp?ID=SY4080&keywords=relay&form=KEYW ORD). It's a good arrangement. It allows the use of a wide variety of low voltage switches to be used and also avoids running the 240 ac to the front of the amp.

Cheers,

Rob

15th June 2009, 02:40 AM	#1
boxerboxer diyAudio Member Join Date: May 2009	Power switch location.. I'm working on a build of Steve Bench's RIAA5 using salas's shunt reg. I'm planning on putting the power supply in a separate enclosure which will be out of sight (and maybe difficult to reach. It would be nice to have the on/off switch on the main unit. Is there a safe way to do that? Lifting the ground for the power supply would shut off the preamp but the power supply wouldn't really be off, would it? Or what about a relay in the power supply to disconnect the PT primary? As long as it could handle the current and defaulted to open rather than closed that should be ok, right? Means an extra conductor in the cable from PSU box to pre box but that's not a big thing.

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16th June 2009, 03:44 AM	#2
boywonder diyAudio Member Join Date: Jan 2008 Location: So.Cal.	A relay in the PS module is convenient, also allowing low voltage up to the switch if desired, but you need some "always on" voltage in the PS (for the relay coil) so that when you flip the switch the relay is energized and closes the mains for power-up.

16th June 2009, 03:59 AM	#3
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	A small 'wall-wart' might suffice for a small stand-by supply for the relay. (Even that would be overkill,for just a relay.) Maybe you could find a small PCB mount power trans.

16th June 2009, 04:38 AM	#4
Rob11966 diyAudio Member Join Date: Jun 2007 Location: Australia	Hi Boxerboxer, I have done this with all of my amps. I use a small 9v PCB power transformer and rectify the 9v supply with a simple bridge rectifier and capacitor arrangement. This provides the 12v (or thereabouts) for the relay coil and any LED's/lamps you need to power. As far as the relay goes, I use a 3A solid state optical relay to power the power transformers (like this one -http://www.jaycar.com.au/productView.asp?ID=SY4080&keywords=relay&form=KEYW ORD). It's a good arrangement. It allows the use of a wide variety of low voltage switches to be used and also avoids running the 240 ac to the front of the amp. Cheers, Rob

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