Variable ramp generator

[Grant Richter]

Too bad National discontinued the LM3900.
I understand it is still available from Texas Instruments
and Japan Radio Corp (JRC)

----------
> From: inman at interpath.com
> To: synth-diy at mailhost.bpa.nl
> Subject: Re: Variable ramp generator
> Date: Thursday, July 08, 1999 7:27 PM
> 
> 
> National's Application Note An-72.pdf ("The LM3900: A New Current-
> Differencing Quad of +/- Input Amplifiers" from September of 1972)
> shows a circuit (7.5 Sawtooth Waveform Generator, p. 24) that may 
> do the trick.  I can't say if this is the circuit people are looking
> for, but it certainly seems to allow you to create a ramp that is the 
> ratio of sweep time / reset time, thus changing the slope while 
> maintaining the overall time from Min to Max voltage.
> 
> Is this it?  Better brains will know.
> 
> Someone suggested this ap note recently.  It is unbelievable.  It should
> be called, "Everything You Can Ever Imagine Doing with an Op-Amp."  
> I am going to have my print bound.
> 
> Elliot