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 300x163

Coil Capacitor meter schematic components

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lc meter components

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