[sdiy] How much DMM accuracy do you need?

[Adam Schabtach]

It is true that you can calibrate your VCOs to your MIDI-CV converter
without an accurate meter because you're making the system internally
consistent. As I see it, you need the meter in two circumstances:
1) You're working on equipment that you might give/sell to someone else. 
2) You happen to change MIDI-CV converters, you notice your oscillators are
no longer tracking correctly, and you want to know whether some highly rated
commercial MIDI-CV converter is at fault, or whether it turns out that your
cheap homebrew converter is actually more accurate. Does this sound like a
true story? It is. :-)

I don't know of a way to _test_ resistors without an accurate meter. It
seems, though, that you could _match_ resistors without a super-accurate
meter. Does that make sense? 

--Adam

> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl 
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of 
> cheater cheater
> Sent: Wednesday, October 07, 2009 10:12 AM
> To: synth-diy
> Subject: Re: [sdiy] How much DMM accuracy do you need?
> 
> Exactly. You don't need a super expensive DMM for setting up 
> the 1V/Oct output of a midi-cv converter, just need to be 
> able to use other tools to the same effect...
> 
> What other situations require high accuracy? I guess low 
> tolerance resistors.. wonder whether there's a way to test 
> those without a perfect multimeter.
> 
> D.
> 
> On Wed, Oct 7, 2009 at 4:06 PM, Jay Schwichtenberg 
> <jays at aracnet.com> wrote:
> > I go sillyscope for course freq and a guitar tuner or by ear 
> > (providing I have a reference osc) for fine tuning. Getting 
> > instrumentation that could measure stuff as good as you 
> want it is going to cost a lot.
> >
> > Jay S.
> >
> >> -----Original Message-----
> >> From: synth-diy-bounces at dropmix.xs4all.nl
> >> [mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of 
> Justin Owen
> >> Sent: Wednesday, October 07, 2009 4:08 AM
> >> To: cheater cheater; synth-diy
> >> Subject: Re: [sdiy] How much DMM accuracy do you need?
> >>
> >>
> >> -----Original Message-----
> >> From: cheater cheater [cheater00 at gmail.com]
> >>
> >> >OK. How much accuracy do you *really* need there?
> >>
> >> IMHO "need" is a relative term. I managed to build my first few 
> >> synths with no more test kit than a £5 logic probe and a £3 DMM 
> >> (which has since been replaced - but still gets used).
> >>
> >> The next few builds *needed* an oscilloscope - so I bought 
> a 2nd hand 
> >> 20Mhz dual trace scope. I couldn't get by without it now and I'm 
> >> looking at buying a second, better, 4 trace scope.
> >>
> >> For my current project - there's no way I could complete 
> it properly 
> >> without a dedicated frequency counter.
> >>
> >> Perhaps this is more of an observation than an answer... :)
> >>
> >> Justin
> >>
> >>
> >>
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> >
> >
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