[sdiy] Best way to limit control voltage

[Grant Richter]

Hi Larry,

You might want to look at the bottom circuit at this URL

http://www.musicsynthesizer.com/DIY/Grant/OTA.html

It is an OTA based voltage limiter, which can be made with VERY sharp
corners.

I have built several of these as audio fuzz units. 1/2 of a LM13700 can
substitute for the 3080. Using a TL074 in place of the LM110 allows
increasing Rabc to 330K from 27K. Also, the voltage setting pots should be
buffered with op-amp voltage followers before the diodes.

The clipping corner transition can be made sharper than a tube based
clipper.

> From: "J. Larry Hendry" <jlarryh at iquest.net>
> Date: Sun, 13 Mar 2005 22:38:32 -0500
> To: <music.maker at gte.net>, <synth-diy at dropmix.xs4all.nl>
> Subject: RE: [sdiy] Best way to limit control voltage
> 
> Oh, now there is a variation on clamping I had not considered. That is
> setting the opposite end of the diode (plus the junction drop when
> conducting) for the value.  That might be great since I need many copies of
> this circuit  I could use a couple of constant reference voltages and clamp
> several of my circuits to the same voltage references.
> Thanks,
> Larry
> 
> 
> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Scott Gravenhorst
> Sent: Sunday, March 13, 2005 8:56 PM
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] Best way to limit control voltage
> 
> 
> Sounds like a job for a diode limiter or clamp circuit.  As long as the
> input
> voltage is below the clamp, it varies normally because the diode is not
> conducting, but when the input goes above (or below with a reversed diode)
> the clamp, the diode conducts and forces the output to maintain a
> programmable level.  The programming is done by supplying a constant voltage
> at the other end of the diode.
> 
> "J. Larry Hendry" <jlarryh at iquest.net> wrote:
>> I'd like to tap into the vast expertise again and ask what methods people
>> are using to be efficient with limiting a control voltage.  I am designing
> a
>> circuit that will have more than one input.  One of the inputs needs to be
>> capable of producing the full output range needed in the circuit.  But, I
>> also want to limit (or clamp) the output so it does not exceed my
>> predetermined values.  The sum of the inputs might normally cause that to
>> happen.  I cannot solve this with scaling.  So, I need to consider
> efficient
>> ways to clamp the output to within a certain range.  I have an idea that
>> will work.  But, it is not as part efficient as I would like to be.  So, I
>> would appreciate hearing from others about their approach to this issue.
>> 
>> Thanks
>> Larry Hendry
>> 
>> 
> 
> ---------------------------------------------------------
> - Where merit is not rewarded, excellence fades.
> - Hydrogen is pointless without solar.
> - What good are laws that only lawyers understand?
> - The media's credibility should always be questioned.
> - The only good terrorist is a dead terrorist.
> - Governments do nothing well, save collect taxes.
> 
> -- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
> -- Linux Rex         | RedWebMail by RedStarWare
> -- FatMan: home1.gte.net/res0658s/fatman/
> -- NonFatMan: home1.gte.net/res0658s/electronics/
> -- Autodidactic Master of Arcane and Hidden Knowledge.
> 
> 
>