[sdiy] Monitoring my Dotcom system's supply voltages

[Paul Perry]

 If one simply wants a qualitative indication of power line stability, 
perhaps an audible indicator would be more useful.
Taking the interference/noise component from the power rail, amplifying it, 
and running it to a ring modulator with (say) a 70Hz square wave on the 
other input should give an audible result when noise is on the line - but I 
can't say that it seems a very useful thing to have.

paul perry melbourne Australia

----- Original Message ----- 
From: "nicolas" <nicolas3141 at yahoo.com.au>
To: "Synth DIY" <synth-diy at dropmix.xs4all.nl>
Sent: Friday, September 14, 2012 10:10 AM
Subject: Re: [sdiy] Monitoring my Dotcom system's supply voltages


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/_______________________________________________
>> Synth-diy mailing list
>> S
>> ynth-diy at dropmix.xs4all.nlhttp://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>
>>
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