[sdiy] Monitoring my Dotcom system's supply voltages

Fri Sep 14 15:21:12 CEST 2012

I also realise that if any VCC dependant component 
specially oscillator components see a 14.90v instead of 15.00v
it will have noticable frequency drift and it's not acceptable.
If the VCC lines vary of 0.1volts easily that means
too much loading or bad regulated supplies.
The point is to have reliable supplies and monitor them. No cheapy stuff.
2 x  Power-One HCBB-75W-AG like mine are reliable stuff.
They have each +/-15v at 1.7amp  and +5v at 6amp.

JP 

 On Fri 14/09/12 09:49 , Tristan tu at alphalink.com.au sent:
> Do you realise that 14.90v is only a 0.67% error for a nominally 15v power
> supply? Most cheap DC power supplies will have this level of deviation or more with changes in
> temperature, loading etc.
> /Tristan
> 
> On Fri, Sep 14th, 2012 at 9:36 PM, Jean-Pierre Desrochers  ricom.ca> wrote:
> > > this thread begs the question:
> why?> > I'd say get a good power supply and trust
> it.  no?> 
> > Simple reason:
> > Anything goes wrong (voltage dropping because of
> any shorts) with the normal > Supply lines
> > ---> I'll see what VCC line is in trouble
> (panel led OFF) and fix it faster.> I will also set the threshold to around 0.10v
> below a normal supply line.> Ex: Lower than +14.90v on the +15VDC line will
> shut the led OFF on the > +15VDC led panel.
> > JP
> > 
> > 
> > ----- Original Message ----- 
> > From: "Giorgio"  achine at gmail.com>> To: "nicolas"  las3141 at yahoo.com.au>> Cc: "Synth DIY"  ynth-diy at dropmix.xs4all.nl>> Sent: Thursday, September 13, 2012 11:30
> PM> Subject: Re: [sdiy] Monitoring my Dotcom
> system's supply voltages> 
> > 
> > > this thread begs the question:
> why?> > I'd say get a good power supply and trust
> it.  no?> >
> > >
> > >
> > > On Sep 13, 2012, at 8:10 PM, nicolas  las3141 at yahoo.com.au> wrote:> >
> > >> Simple comparators will show you
> overall sag, but a bigger problem in a > >> synth is noise, spikes, hum, transient
> glitches, etc.  So some way of > >> detecting any small AC component on
> those lines would be very useful, > >> which could be low freq hum or audio
> crosstalk or hi freq digital > >> crosstalk or broad spectrum noise or RF
> interference.  And also a way of > >> capturing very brief excursions (+ve
> and -ve) and latching an LED for a > >> few seconds so that you can see it, in
> case you are getting transient > >> spikes or dropouts.  Something that
> could do all that reliably and simply > >> would be useful thing to have
> :)> >>
> > >> Nicolas
> > >>
> > >>
> ________________________________> >> From: Stewart Pye  ye at optusnet.com.au>> >> To: Synth DIY  ynth-diy at dropmix.xs4all.nl>> >> Sent: Thursday, 13 September 2012 8:17
> AM> >> Subject: Re: [sdiy] Monitoring my
> Dotcom system's supply voltages> >>
> > >> If you use a pic you'd still have to
> divide down the input voltages. I'd > >> probably just use a single voltage
> reference and a quad comparator. You'd > >> have to put a voltage divider on all
> the inputs you are measuring, but > >> the voltage reference can be used for
> all inputs if the voltage divider > >> for the negative voltage is an
> inverting amplifier. That's only 6 or 7 > >> resistors (plus the LED current limit
> resistors) 1 voltage ref, 1 op amp > >> 1 quad comparator. You may even be able
> to get away with using a quad op > >> amp for the comparators + op
> amp.> >>
> > >> Alternatively use two voltage
> references, or invert the positive one with > >> an op amp.
> > >>
> > >> Regards,
> > >> Stewart.
> > >>
> > >>
> > >>
> > >> On 9/13/2012 1:35 AM, Jean-Pierre
> Desrochers wrote:> >>> Good point
> AndrÃ©,> >>>
> > >>> I've been browsing around lots of
> analog solutions> >>> so far ending with voltage
> refernces + voltage comparators> >>> + a bunch of passive
> components..> >>> I'm starting to think of a digital
> solution (!!)> >>> Just a simple Microchip PIC with
> analog inputs> >>> could do all the voltage checks,
> hysteresis and> >>> leds driving for my 3 voltages, and
> that in one chip.> >>> The -15v will even be monitorable
> with some tweekings..> >>> I already have a +5v to supply it
> without> >>> disturbing my +/-15v lines with
> digital spikes..> >>> Hmmm, the only problem with micros
> is futur repairs (in the next xx > >>> years)..
> > >>> Much easier to replace analog parts
> than programmed PIC's.> >>> I'm still doing some
> searchs..> >>> JP
> > >>>
> > >>>
> > >>>   On Wed 12/09/12 11:55 , Andre
> Majorel aym-htnys
> @teaser.fr sent:> >>>> On 2012-09-12 09:13 -0400,
> Jean-Pierre Desrochers wrote:> >>>>
> > >>>>> Here what I found by
> chance:> >>>>> http://www.reuk.co.uk/TL431-Battery-Voltage-Monitor.htm> >>>> This thread on
> sci.electronics.components may be of interest :> >>>>
> > >>>> http://groups.google.com/forum/?fromgroups#!topic/sci.electroni
> > >>>>
> cs.components/uDYcuMy4RYQ> >>>> What I got out of it is that
> using a TL431 with less than 3 ÂµF> >>>> between anode and cathode is
> asking for trouble.> >>>>
> > >>>> -- AndrÃ© Majorel
> > >>>>
> > http://www.teaser.fr/~amajorel/_____________________
> __________________________> >>>> Synth-diy mailing
> list> >>>> S
> > >>>>
> > ynth-
> diy at dropmix.xs4all.nlhttp://dropmix.xs4all.nl/mailman/listinfo/synth-diy> >>>>
> > >>>>
> > >>>
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