[sdiy] Power supply spike

[harrybissell at copper.net]

The relay would be on the DC side of the power supply and once
the relay closed... there would be no voltage drop across
the contacts.  The capacitors would have charged to steady state
before the relay closed so the chance of noise pickup would be
small...

... but not to say that you might not have some problem with it.
You could avoid any possibility by using a separate relay... imho
you could make it work well with only one.

H^) harry



>
>
>
>---- Original Message ----
>From: chris at chrismusic.de
>To: synth-diy at dropmix.xs4all.nl
>Subject: Re: [sdiy] Power supply spike
>Date: Mon, 26 Feb 2007 11:20:14 +0100
>
>>On Fri, 23 Feb 2007 15:40:05 -0000 harrybissell at copper.net wrote:
>>> If you get that large of a spike you might want to
>>> soft start the power supplies. You add resistors in series
>>> with the DC rails... then wait like one second for the voltage
>>> to rise. Short the resistors out with relays. This might remove
>>> all the audible thump during turn-on. As you have relays there
>>> anyway... disable the audio output at the same time (for free
>>> with an extra contact...)
>>> 
>>> H^) harry
>>
>>Um, power switching and audio on the same relay? My gut feeling
>tells me
>>I wouldn't like that very much. Maybe with that 110 V toy
>electricity
>>that is merely tickling ;-), but over here with 230 V I prefer to
>keep a
>>safe distance from audio traces. 
>>I may be a bit over-cautious, but even after 30 years I treat mains
>>voltage with quite some respect. I keep careless messing to the low
>>voltage side <gr>
>>
>>Christian