Vijit Dubey
Member
Wow. Yeah. I'm thinking about it now. I'll come up with a schematic and discuss with you. Please wait.I thought you knew how the 4046 works... pin 14 is for a low level AC input signal
if you dont understand how to design this, how are you expected to find a solution?
IF you dont have a counter do you know how to calibrate VCO precisely to 1%?
To make the automated circuit you imagine... think of block diagrams then and specify all inputs and outputs.
- VCO: 0-Vcc input, 5:1 freq range output, 300R output (internal ) impedance
- Low impedance Driver: for 5 Ohm load.
- driver to 0.5Ohm parallel resonator with 5 Ohm current sense to ground.
- Precision rectifier Op Amp for resonant peak signal. Vp
- Negative sweep integrator sample and hold circuit for V_ctrl
- 1 shot cct to dump Cap voltage to Vcc with MOSFET switch to restart sweep.
- Sample and hold cct #2 for peak signal. (low leakage switch & low leakage Film cap)
- Comparator between V(t) - V(t-1) between S&H#2 cap and rectifier out , +Ve out if signal > Hold voltage to resample during pulse .. logic level out.
- ! shot timer to stop test if resample pulse has not occurred within 1 ms and hold V_Ctrl
- then use control limits or look up table for Vctrl before it drifts. for V vs F
- Or use cheap counter circuit with VCO direct to Crystal input pin with small series cap.
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