Vermes
Advanced Member level 4
It is a small project on Atmega8 with LCD from Nokia3310, 2 buttons, operational amplifier, few resistors and capacitors. The measurement is based on the measurement of the frequency of run generated by the generator LC.
Double operational amplifier AD8092ARZ was used in this device. Atmega operates on the internal oscillator on a frequency of 2MHz. Each measurement uC is put to sleep for about half a second to reduce the current consumption. Average power for continuous operation is about 1-2mA.
Handling
The device has two buttons. One is used to run on and off by holding. The second one is the calibration button. Starting the device by holding down both buttons runs in the inductance calibration mode. After running in calibration mode, you can set the measurement value for a standard inductance by the left button. In normal mode, the left button is used to adjust the contrast.
Disabling is done by disconnecting power of all peripherals by uC and the transition to POWER DOWN mode.
Current consumption is less than 1uA.
Power – CR2025.
Time of work – about 1,5-2h.
Schema:
Link to original thread (attachments and video) – Miniaturowy miernik indukcyjności