Nowadays is so easy to build precision digital LC meter with LCD display and microcontrollers. But, what about 1997? There is my first very precision ANALOG LC METER. Look at this, but do not fall in love in retro princess from past!! The analog LC-meter project (AP-LC1) have more then 3% accuracy. Really! There is no balanced bridge, or very expensive components inside.
We read the value on 100mikroA DC instruments with accuracy scale of 2%. It is very simple, only one integer circuit (HEF40106BP). I used 5 from 6 Hex Schmitt Trigger organized like a independent oscillators: 10Hz, 100Hz, 1KHz, 10KHz i 100KHz. If we want to use a higher frequency (1MHz) we must find original transistor BSX20 instead BF198.
Analog LC Meter, back to the past 1996 – [Link]