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

[Harry Bissell Jr]

The simplest way would be to put four 1N4004
(or higher) diodes in series with the connection from
the +15 to the +12.  They should go

+15  A-K-A-K-A-K-A-K +12

Each diode will drop about .7 volts... so four
in series will drop 2.8V.  Be prepared to add a fifth
diode if the voltage (you measure) when its connected
is still too high.

Or use a 7812 voltage regulator running on the +15V
supply.

H^) harry

--- Rutger Vlek <rutgervlek at hotmail.com> wrote:

> 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
> > >
> > >
> > >
> >
> 
> 
>