[sdiy] Monitoring my Dotcom system's supply voltages

[Tristan]

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 <jpdesroc at oricom.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" <dancemachine at gmail.com>
> To: "nicolas" <nicolas3141 at yahoo.com.au>
> Cc: "Synth DIY" <synth-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 <nicolas3141 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 <stewpye at optusnet.com.au>
> >> To: Synth DIY <synth-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 André,
> >>>
> >>> 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 at 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 µF
> >>>> between anode and cathode is asking for trouble.
> >>>>
> >>>> -- André Majorel 
> >>>>
> http://www.teaser.fr/~amajorel/_______________________________________________
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> >>>>
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> >>>>
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