[sdiy] Ring modulator and power supply questions -> PSU now

[Rutger Vlek]

Thanks for the good suggestions. I'll try to see if it will solve the 
problem with the Ring Modulator. Currently i'm working on a nice mahogany 
casing! Very sweet indeed ;).

I still have one remaining question about the power supply. I asked it 
before, does someone know a good solution for it? I run my synth on 15V but 
i have a keyboard i want to build in that runs on 12V (originally it was an 
Evolution MK149). What is the simplest way to convert the 15V to 12V? Does 
someone now a circuit that can do this? Or can the Evolution handle the 15V?

Regards,

Rutger


>From: Harry Bissell Jr <harrybissell at prodigy.net>
>To: Rutger Vlek <rutgervlek at hotmail.com>, synth-diy at dropmix.xs4all.nl
>Subject: Re: [sdiy] Ring modulator and power supply questions
>Date: Thu, 20 Oct 2005 13:19:45 -0700 (PDT)
>
>I'd do this...
>
>I would put the 100K resistors where the diodes
>are, and put the diodes where the 100K resistors
>are (cathode to the 100K resistors, anode to ground).
>
>Now the 100K resistors will limit the input current
>and the diodes will stop the inputs from going more
>than .7V below ground.
>
>Then, reduce the power supply voltage to the chip.
>You can use a resistor in series with pin 14 of the
>chip and a zener diode to ground.
>
>The input sensitivity will be 1/2 the supply voltage,
>so with 15V you need a minimum of +7.5V.  Most synths
>have a range of maybe +/- 5V so you are hosed there...
>
>If you reduce the supply voltage to maybe 5V, the
>trigger level would be around 2.5V and should work
>with almost any synth.
>
>You can use any waveform, although it is really
>intended for pulse waves.  You can substitute the 4093
>Quad NAND Schmitt Trigger to get better operation on
>non=pulse waves. Essentially that would convert the
>waves to pulse for you...
>
>H^) harry
>
>--- Rutger Vlek <rutgervlek at hotmail.com> wrote:
>
> > Hello everyone,
> >
> > i'm building an analog synth containing a version of
> > the SBM RingModulator
> > (http://www.ele4music.com/pdfs/sbm.pdf). I'm running
> > it on 15V instead of
> > 12V and it works fine except that the input's have
> > to be very high to get
> > the thing working! Plugging the VCO's into it
> > doesn't work, but boosting
> > them through a mixer first does work. What is the
> > simplest way to get the
> > input threshold of the RingMod down or the
> > inputsignal up in volume? I'm
> > using the latest Oakley VCO's.
> >
> > Another question is about power supply. I run my
> > synth on 15V but i have a
> > keyboard i want to build in that runs on 12V
> > (originally it was an Evolution
> > MK149). What is the simplest way to convert the 15V
> > to 12V? Does someone now
> > a circuit that can do this? Or can the Evolution
> > handle the 15V?
> >
> > Regards,
> >
> > Rutger
> >
> >
> >
>