Constant Slew Rate LFO

[Mike I.]

Terry,
This might be what you want - assuming constant slew rate = constant 
slope for a triangle waveform. Start with  the simple two op amp 
(Schmitt trigger + integrator) triangle generator. Replace the resistor 
that connects the integrator output to the Schmitt (+) input with a 
variable resistor (pot) - this becomes the DEPTH control. The variable 
resistor (pot) that connects the Schmitt output to the integrator op amp 
(-) input gets labelled as SLOPE (was RATE in the original constant 
amplitude triangle configuration). This should give (untested...) a 
constant slew rate variable amplitude triangle - as the amplitude 
increases, the frequency decreases. The triangle is centered about zero 
volts. OTA's could be used to make this voltage-controlled. A version 
that has the bottom of the triangle fixed at zero volts could be useful 
too.
Mike