[sdiy] Ring modulator and power supply questions

[Harry Bissell Jr]

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
> 
> 
>