I need to design a linear R to F converter ,I'm able to change Resis. to volt. linearly but I can't continue ,I tried to make it with the linear VCO but it didn't work in pspice schematic even if I plot it exactly as it's here :
http://www.seekic.com/forum/22_circuit_diagram/19893_LINEAR_VCO.html
the VCO in schematic :
http://forum.allaboutcircuits.com/attachment.php?attachmentid=24577&stc=1&d=1289907772
Q1: to see the out. (sawtooth & square wave)of this ckt in the probe should I run dc/transient analysis cuz all I can see is a constant voltage in tran. on both amps. out. and in there's no DC sweep ?

Q2: how can I in the end show a probe of resistance vs frequency if pspice run dc (no time and freq.), transient(no dc sweep), ac analysis separetly ?

here's the ckt made :
http://forum.allaboutcircuits.com/attachment.php?attachmentid=24578&stc=1&d=1289908540
as u can see all sources are dc and after the buffer everythin seems wrong ...
Q3: the capacitor in my ckt seems to has no effect at all ,why ?
THANX THANX THANX I appreciate any comment....

 

Your V6 exceeds the supply rails for U3's input. This will lead to unpredictable behavior in a simulation. With real parts, this can result in smoke.

The LF411 is obsolete. You should select an opamp that is still in production.

Be certain to keep the input voltages within the common-mode limits of the opamps being used. Frequently, this is Vee+1.5v to Vcc-1.5v; although the LM324 can sense input to the negative rail.

The LM324 is a very old and slow opamp. You should select a more modern opamp.

 

Your V6 exceeds the supply rails for U3's input. This will lead to unpredictable behavior in a simulation. With real parts, this can result in smoke.

The LF411 is obsolete. You should select an opamp that is still in production.

Be certain to keep the input voltages within the common-mode limits of the opamps being used. Frequently, this is Vee+1.5v to Vcc-1.5v; although the LM324 can sense input to the negative rail.

The LM324 is a very old and slow opamp. You should select a more modern opamp.

thanks for reply ,but if you tell me what to use as integrator and as a schmitt trigger and their supply voltage I appreciate it.....