SynthModules

I wrote a quick program for Gary to check the inputs and outputs.  I 
uploaded it (io-test.djb.bas) to the DJB Programs folder.

The start switch sends the decimal values of the four inputs to 
Terminal1 in the IDE program.

The stop switch increments the outputs from 0.75 volts to 9.75 volts 
(octaves of A).

I did a quick check of my PSIM with a voltmeter and the outputs seemed 
off a fair amount.  I then calibrated two VCOs to A-440 with my 
keyboard, and then drove one from the PSIM.  The frequency was spot 
on.  I guess this shows the accuracy of ears over low cost volt 
meters.

Directions are included inside the program.

Dave


--- In SynthModules@yahoogroups.com, "Gary Chang" <gchang@...> wrote:
>
> Brice, yes, it does make sense - and perhaps I need a more accurate
> meter to to the calibration.
> 
> gary
> 
> 
> "Brice D. Hornback" <bdh@> wrote:
> >
> > Gary, these are all the exact same PSIM-1 modules.  All the PCBs 
and 
> > components were purchased at the same time.  All the resistors are
> 1%.  When 
> > I calibrated the modules I've already sent you, I used a Fluke 
volt
> meter 
> > that was calibrated against a NIST certified volt meter/voltage
> source.  You 
> > could use one of your other PSIM-1 modules as a precision voltage
> source to 
> > calibrate this PSIM-1 module.  Simply output a voltage from #1 
into
> a VCO 
> > and the same voltage from #2 into a second VCO and zero beat them 
by 
> > adjusting the trim pot on #2.  Dave's idea of using a 440 Hz tone
> generator 
> > is a great idea and you could accurately calibrate all your PSIM-1
> modules 
> > to that source.
> > 
> > Also, the Atom-Pro can output an audio tone (such as 440 Hz) on 
the AUX 
> > port.  So in effect, you can use the PSIM-1 to calibrate itself by
> feeding 
> > the output of the audio tone on the AUX port to an input to sample 
the 
> > voltage and adjust the trim pot so the output matches what is 
being
> fed into 
> > it.  You could have all the LEDs get brighter to indicate when it 
is in 
> > tune.  I started to write a program to do that at one time but 
never 
> > finished it.  The program could even be set to automatically
> calibrate (set 
> > an offset variable) itself on startup.  I'm not sure how accurate
> that would 
> > be... but in theory it should work.
> > 
> > For starters, most volt meters (unless they are NIST certified) 
are
> not all 
> > that accurate.  One meter may display 10.666 volts and another
> 10.555 or 
> > whatever.  If I were you, I'd just measure the voltage at TP1 on 
one
> of your 
> > other PSIM-1 modules and set this one to whatever your volt meter
> reads and 
> > see if that works.  That may be the easiest and fastest way.  So, 
if
> your 
> > volt meter reads PSIM-1 #1 at 10.555 volts... set this one to that
> as well. 
> > The volt meter may be off (or mine may be off)... but that way, 
they
> will be 
> > the same.  Does that make sense?
> > 
> > Best regards,
> > Brice
> > 
> > ----- Original Message ----- 
> > From: "djbrow54" <davebr@>
> > To: <SynthModules@yahoogroups.com>
> > Sent: Thursday, November 16, 2006 12:57 AM
> > Subject: [SynthModules] Re: Completed PSIM burning in....
> > 
> > 
> > >I assume the input attenuation resistors are 1%.  In a voltage 
divider
> > > with 10 volt input, the output could be 5 volts +/- 50 mV.  
That's a
> > > 100 mV difference potentially between channels.  100 mV is 
greater
> > > than a semitone so you could be off that much in sampling.  The 
only
> > > way to correct this would be to either trim each channel to 
calibrate
> > > it, or figure out how much it is off and use an offset 
multiplication
> > > in software.
> > >
> > > The other possibility is the 10.666 volt reference as has been
> > > mentioned.  Sending a 1440, 1824, 2208, and 2592 to the 4 Dacs 
will
> > > result in 3.75, 4.75, 5.75, and 6.75 volts.  These should 
correspond
> > > to "A" octaves.  You can then adjust the 10.666 by beating a VCO
> > > against a 440 Hz reference, which I assume would be more 
accurate than
> > > trying to set it with a voltmeter.
> > >
> > > Is your software quantizing?  If so, it wil magnify the error.
> > >
> > > Dave
> > >
> > >
> > >
> > > --- In SynthModules@yahoogroups.com, "Gary Chang" <gchang@> 
wrote:
> > >>
> > >> After precisely calibrating the module, the new PSIM 
consistently
> > >> outputs a sampled cv that is higher that the other PSIMs that 
are
> > >> similarly trimmed.  I know that this is a moot point for those 
who
> > >> have only one PSIM, and, for that matter, I can run Mike 
Firman's
> > >> quadrature lfo program on the new one and use the older units 
that
> > >> match for other stuff, but, I have to wonder - is there any
> > > difference
> > >> between the old and newer PSIMs?
> > >>
> > >> gary
> > >>
> > >> "Brice D. Hornback" <bdh@> wrote:
> > >> >
> > >> > Gary,
> > >> >
> > >> > You need to calibrate the reference voltage (there is a blue 
trim
> > >> pot next
> > >> > to U5 labeled RT1) to exactly 10.666 VDC between ground and 
TP1.
> > > It's
> > >> > labeled on the PCB next to the test point.
> > >> >
> > >> > Best regards,
> > >> > Brice
> > >> >
> > >> > ----- Original Message ----- 
> > >> > From: "Gary Chang" <gchang@>
> > >> > To: <SynthModules@yahoogroups.com>
> > >> > Sent: Wednesday, November 15, 2006 12:22 AM
> > >> > Subject: [SynthModules] Completed PSIM burning in....
> > >> >
> > >> >
> > >> > >I assembled my new PSIM tonight (with the help of 
disassembling
> > > one
> > >> > > that Brice built for me 2 years ago).  It works - but when 
run
> > >> > > identical programs (gc-sah-sr-nq-djb.bas), the two modules
> > > output two
> > >> > > different pitches when sampling the exact same source.
> > >> > >
> > >> > > Is there a way to calibrate the modules to be identical?
> > >> > >
> > >> > > gary
> > >> > >
> > >> > > p.s.
> > >> > >
> > >> > > Assembly really wasn't hard - and I have the module working 
now.
> > >> > > Those of you who don't have their modules should really 
consider
> > > this
> > >> > > option.... 8^)
> > >> > >
> > >> > > gc
> > >> > >
> > >> > >
> > >> > >
> > >> > >
> > >> > > Be sure to check out the primary Web site at:
> > >> > > http://www.SynthModules.com
> > >> > >
> > >> > > Yahoo! Groups Links
> > >> > >
> > >> > >
> > >> > >
> > >> > >
> > >> > >
> > >> >
> > >>
> > >
> > >
> > >
> > >
> > >
> > > Be sure to check out the primary Web site at:
> > > http://www.SynthModules.com
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> >
>