[SOLVED] Frequency to Voltage conversion using Monostable Multivibrator

[elisemark]

I have an LC resonnator /oscillator at 800Khz and the frequency is changing as the coil length changes. I need to output a dc signal that is varying as function of my signal frequency change . I tried PLL with Cd4046 with no luck .
anyone has any idea how to achieve this with a HEF4538B or even the the IC555 timer.

thanks

 

[FvM]

I tried PLL with Cd4046 with no luck

Either you didn't set up the VCO frequency range correctly or you didn't provide a suitable "digital" input signal for the phase comparator. Both problems would probably happen with a 4538 as well.

 

[elisemark]

thansk FvM
for the Cd4046 as far as the VCO I have C4 set to 470pf and R at pin 11 set at 10K (correction my Fc=850Khz)
this should work.

 

[elisemark]

anyone has any schematic on how to design the F/V converter circuit given my oscillator resonnating at 800Khz using the 4538 monostable ? also can the LM331 work at such high frequencies ?