Sense Small Inductance Changes Over A Wide Range


Posted on Feb 4, 2014

Small inductance changes on the order of 0. 01% can easily be sensed over a wide range with a simple circuit connected to a serial port ( see the figure ). Using a classic Colpitts oscillator interfaced to an eight-pin Atmel ATtiny12-8 microprocessor, the period of multiple oscillator cycles ”which is proportional to the inductance ”can be sensed


Sense Small Inductance Changes Over A Wide Range
Click here to download the full size of the above Circuit.

. Applications include metallic proximity sensing and seismic detection. The Colpitts oscillator output is level-shifted using R4 and R5 to a zero of about 1. 2 V, which is the microprocessor`s analog comparator reference voltage. The oscillation frequency of a Colpitts oscillator is: The RISC-based microprocessor (operating at an instruction rate of 8 MIPS) counts the number of LC oscillator cycles between a fixed number of crystal-oscillator clocks. With the circuit shown, values of C1 and C2 should be chosen so that the maximum LC oscillator frequency is about 500 kHz. Frequency measurements are made for 32. 5 ms. At the end of each measurement, four hex ASCII characters representing the number of cycles of the LC oscillator are serially transmitted. The online version of this article at includes the ATtiny12 source code and HEX file.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

stable guitar FM transmitter
Audio Oscillator schematic
Signal-injector
Preamplifier for magnetic phono cartridges schematics
RGB LED Strip Circuit with Arduino
Video Switch for Intercom System
NSLU2
ultrasonic transmitter circuit
Random Flasher for 8 LEDs Project
mercury v8 monterey 1963 wiring diagram
Fun with LEDs
Carbon Mic Replacement To Magnetic Mike Converter Circuit
Transmitting Audio Streams in Automotive Applications Using the MAX9205/MAX9206 LVDS SerDes
BJT H-bridge Implementation
Telecard reader with AT90s2313 micro
Brightness display circuit 555
Multi-output power supply circuit (MAX1902)
Low-distortion audio limiter circuit diagram
PGA103 offset voltage correction circuit diagrams



Top