This LC meter circuit can measure coils and capacitors. When Lx or Cx is connected in the circuit the oscillator frequency will decrease and this decrease is measured by a frequency-voltage converter build with T3 and T4. To adjust this lc meter circuit with P1 and P2. LC meter precision is 3%.
Scale calibration can be achieved with this formula: ni = nm(1 – fr)/(1 – fc) where ni is number of divisions measured on the scale, nm = total number of division of the scale, fr = relative frequency, fc = the smallest relative frequency measured.


The total power consumption is 12mA at 12V when the LC measurement occur.


LC meter circuit diagram

lc-meter-schematic

Coil Capacitor meter schematic components

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lc-meter-components